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CHAPTER
27
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REPAIR/REPLACEMENT ACTIVITIES
FOR NUCLEAR POWER
PLANT ITEMS
Richard E. Gimple
INTRODUCTION
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Article IWA-4000 of Section XI of the Boiler and Pressure
Vessel (B&PV) Code [1] contains the requirements for performing
repair/replacement activities on nuclear power plant items. The
repair/replacement activity requirements of IWA-4000 apply to a
component after it has met all the Construction Code requirements.
This chapter examines the background of these repair/replacement
activities, notes some of the significant restructuring of paragraphs
and terminology and important changes in repair/replacement activity requirements since the original 1970 Edition, and reviews and
discusses the requirements in IWA-4000 in the 2007 Edition of
Section XI. This chapter is beneficial to personnel performing such
repair/replacement activities as designing plant modifications,
obtaining replacement items, and performing welding, brazing,
defect removal, fabrication, installation, examination, and pressuretesting activities.
Repair/replacement activity is the current term used in Section XI
to encompass former Section XI terms of repair, replacement,
modification, and alteration. This chapter uses this term except to
refer to an earlier edition or addenda where previous terms were
used to convey specific distinctions, such as repair or replacement. The origin of the term and the reasons for changing to the
current terminology are discussed later in this chapter.
While Chapter 27 in the first and second editions of the
Companion Guide used the 1999 Addenda and 2004 Addenda,
respectively to discuss IWA-4000 requirements, this third edition has been updated to the 2007 Edition. Personnel using
other editions and addenda will still find the information in this
chapter worthwhile. Many of the concepts have remained the
same over time, and the explanations regarding the 2007
Edition may be important for personnel who use earlier editions
and addenda. Similarly, personnel who eventually use later editions and addenda of Section XI should still find this chapter
important, for it provides the basis and explanations for
unchanged provisions.
Many countries use Section XI, for it is often recognized as an
international standard. To further this recognition as an international
standard, Section XI was revised in the 2004 Edition to include
equivalent SI units for all US Customary units. IWA-1700 was also
added to provide requirements regarding use of units. In recognition of Section XI’s international use, it should be noted that most
of this chapter’s content applies regardless of the country where
the information is used. In most countries where Section XI is
used, regulatory authorities impose requirements that affect the
operation of nuclear power plants. Comments in this chapter
regarding regulatory authority requirements are limited to those
imposed in the United States; the reader in another country should
review and implement the regulatory authority requirements
imposed in his or her particular country.
As a benefit to the reader, numerous Code interpretations are
included in this chapter to aid in clarifying and understanding the
material. In addition to interpretations, numerous Code Cases are
noted for the reader’s consideration. Because a Code Case is considerably different from an interpretation, some information
regarding interpretations and Code Cases is provided to ensure
that the reader properly understands the distinction between the
use of each. Further information can be found in Section XI
Mandatory Appendix V, which describes the submittal to ASME
of technical inquiries (requests for revisions or additions to Code
requirements, requests for Code Cases, and requests for Code
interpretations) and provides information about each type of technical inquiry. In the 2005 Addenda, each of the Appendices on
technical inquiries in all to the B&PV Code Sections were revised
and standardized to aid users.
Each Section XI interpretation is a response to a technical
inquiry posed to the ASME or clarification initiated by Section XI
committee personnel. An interpretation is not part of the Code
and does not provide new Code requirements, but it does explain
or clarify such requirements. Each Section XI interpretation
applies to the edition and addenda stated in the interpretation or, if
none is stated, to the edition and addenda in effect at the time of
the interpretation’s issuance. Subsequent revisions to the Code
may supersede the interpretation. In addition, revisions to an
interpretation may be published at a later date and take precedence over the previous version of the interpretation. Similarly, if
a later, different interpretation is issued that provides new information, the latest interpretation is considered the most applicable
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The NRC recognizes that the ASME is the official interpreter
of the Code. However, only the NRC can determine whether
the ASME Interpretation is acceptable such that it constitutes
compliance with the NRC’s regulations and does not adversely affect safety. The NRC cannot a priori approve Code interpretations. While it is true that the ASME is the official interpreter of the Code, if the ASME interprets the Code in a
manner which the NRC finds unacceptable (e.g., results in
noncompliance with NRC regulatory requirements, a license
condition, or technical specifications), the NRC can take
exception to the Interpretation and is not bound by the ASME
Interpretation. To put it another way, only the ASME can provide an Interpretation of the Code, but the NRC may make the
determination whether that Interpretation constitutes compliance with NRC regulations. Hence licensees need to consider
the guidance on the use of Interpretation contained in the NRC
Inspection Manual Part 9900 “Technical Guidance” [2].
Interpretations have been of great benefit in clarifying the
Code. The NRC is not restricting the use of ASME
Interpretations. A proposed limitation on their use was not
placed in 10CFR50.55a [3].
Nuclear and Boiler & Pressure Vessel Code Case books, ASME
changed the distribution method for Supplement 12 of the 2004
Edition. The 2007 Edition contained what would previously have
been known as Supplement 12 to the previous edition, resulting in
Supplement 11 being the last supplement to the 2004 Edition.
Another change worth noting is that Code Cases no longer
contain expiration dates. Cases will remain available for use until
annulled by the ASME B&PV Standards Committee.
Section XI Code Cases are applicable to specific Section XI
editions and addenda, i.e., may only be used with a specific
Section XI edition or addenda, or more commonly with a specific
range of Section XI editions and addenda. Each Edition of the
B&PV Nuclear Code Cases contains a Section XI Code Case
Applicability Table. Revisions to the Table are periodically made
and published with the next quarterly Code Case Supplement.
Users of Section XI must validate the applicability of Section XI
Code Cases to the Section XI Edition and Addenda used in their
Repair/Replacement Program before adopting the Case for use.
In this chapter, the discourse identifies a current Code Case when
it is pertinent to the subject being discussed. If the Case provisions
have been incorporated into Section XI by revision, the edition and
addenda that incorporated these provisions are also identified.
Users working with an edition and addenda of Section XI earlier
than the time at which the provisions of the Case were incorporated
may consider adopting the identified Code Case provided it is
applicable to the Section XI Edition and Addenda used for their
Repair/Replacement Program. In addition, there are a few Code
Cases that are appropriate to note separately from any discussion of
current Section XI requirements, for these Cases contain significant
alternatives and/or new technology that do not fit well with discussion of current Section XI requirements. A brief discussion of these
Cases is included in Section 27.14 of this chapter.
In the United States, the use of Section XI Code Cases must be
approved by the NRC, just as the use of specific editions and
addenda of Section XI must be approved by the NRC.
Historically, approval for use of Section XI Code Cases was provided by two mechanisms: (1) inclusion in the NRC Regulatory
Guide 1.147 [5], in which the NRC identifies Cases generically
approved for use; and (2) specific relief request to the NRC with
subsequent approval by the NRC. With the September 22, 1999
Federal Register publication of the change to Federal Regulation
10CFR50.55a, the NRC added a third mechanism when two Code
Cases (N-513 and N-523-1) were approved for use by the NRC
regulations [6]. Code Cases N-513 and N-523-1 were subsequently added to later revisions of Regulatory Guide 1.147 and
removed from 10CFR50.55a. In 2003, the NRC further modified
its mechanism for approval of Section XI Code Cases requiring
Section XI Cases to be in Regulatory Guide 1.147 and requiring
the specific revision of Regulatory Guide 1.147 to be incorporated
by reference in 10CFR50.55a. [13].
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answer. ASME’s procedures provide for reconsideration and
appeal of interpretations. Each volume of interpretations, now
published once a year with each addenda, includes both subject
and numerical indexes to assist the user in locating interpretations, the latter type by means of Code paragraph numbering.
These indexes cover interpretations issued beginning with vol. 12.
Discussions on the use of ASME Section III and Section XI
interpretations in the United States should consider the position of
the regulator who makes these Codes federal law. This position
regarding Code interpretations was taken by the staff of the U.S.
Nuclear Regulatory Commission (USNRC, or simply NRC) and
was included in the September 22, 1999 Federal Register publication of the change to federal regulation 10CFR50.55a. In the discussion of this regulation amendment the following information
regarding ASME Code interpretations was provided:
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Therefore, users of Section XI in the United States need to
assess their use of an ASME interpretation to ensure that the
interpretation does not conflict with NRC requirements applicable
to their nuclear power plant.
A Code Case is a mechanism approved by the Boiler and
Pressure Vessel Committee for early implementation of a Code
revision or for an alternative to Code requirements. Code Cases
for use with Section XI are published in the B&PV Nuclear Code
Cases [4]. Code Cases are not part of Section XI, but can be considered voluntary alternatives to Section XI. When a Code Case is
adopted for use and included in an Owner’s Section XI
Repair/Replacement Program, the provisions of the Case become
mandatory. Because the same Section XI edition and addenda is
usually used throughout the Section XI 10 yr. interval, Code
Cases can be an effective way for one to use later Section XI revisions before being required to update to a later edition or addenda
that contains the desired revision. Additionally, some Code Cases
containing alternatives to Section XI have not been incorporated
into the Code; thus, Code Cases are the only mechanism for
which the use of such alternatives is obtained.
The ASME B&PV Code Case books are published every three
years, similar to B&PV Sections. Supplements are issued each
quarter containing new and revised Cases, annulled Cases, and
errata on previously issued Cases. In the 2007 Edition of both the
27.2
BACKGROUND OF
REPAIR/REPLACEMENT ACTIVITY
REQUIREMENTS
27.2.1
Origin of Repair/Replacement Activity
Requirements
The original concept in the 1970 Edition of Section XI was to
have repairs performed in accordance with ASME Section III. This
reference to Section III did include B31.7 for nuclear piping and
the Pump and Valve Code that, by reference, were both part of
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later Code requirements and the fact that the original Construction
Code and Owner’s Requirements continue to provide an acceptable level of safety.
This diversity in Construction Codes creates a challenge to the
Code Committee personnel writing Section XI repair/replacement
activity requirements. Because the original Construction Code for
a particular nuclear power plant remains valid for performance of
repair/replacement activities for the life of the plant, Section XI
Committee personnel must consider a wide range of Construction
Codes when they write Section XI requirements. The requirements must be written to accomplish the specific intention regardless of the original Construction Code used by a given plant; this
endeavor often requires generalizations that do not provide the
clarity that users expect. In addition, Committee personnel must
consider requirements in legacy Codes that, although decades old,
are still valid and used at older nuclear plants.
Significant Restructuring of Code Paragraphs
and Terminology
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Section XI requirements for repair/replacement activities have
been restructured several times since the original 1970 Edition.
The restructuring of requirements has been necessitated by gained
experience and additional requirements. Because of NRC
Regulations requiring Owners to update to new Section XI editions and addenda every 10 years, the 104 nuclear plants in the
United States use a wide range of Section XI editions and addenda. A summary of some of the significant restructuring changes
and changes in terminology follows. Some of the changes may be
interesting from a historical perspective; others may be of benefit
in the understanding and implementing of later editions and
addenda for plants that are required to update in accordance with
NRC Regulations or that are considering a voluntary update.
(a) Section XI requirements were reformatted in the 1974
Edition and an entirely new paragraph numbering system was
used. For repairs, the format used provided general requirements
in IWA-4000. Additional provisions were contained in IWB/C/D4000 for Class 1, 2, or 3 items. This same format was maintained
until the 1988 addenda.
(b) The repair requirements were substantially rewritten in the
Summer 1978 Addenda.
(c) In the 1988 Addenda, common technical requirements for
Class 1, 2, 3, and MC repairs were consolidated in IWA-4000.
Defect removal requirements in IWB-4120 through IWB-4230,
IWC-4120 and IWC-4200, IWD-4120 and IWD-4200, and IWE4120 through IWE-4230 were moved to IWA-4300. Section XI
half bead welding techniques in IWB-4300 through IWB-4344,
IWC-4300 through IWC-4344, and IWD-4300 through IWD4344 were moved to IWA-4500. As a result, all that remained in
IWC-4000 and IWD-4000 was a statement that the rules of IWA4000 apply.
(d) In the 1989 Addenda, common requirements for replacement
of Class 1, 2, 3, and MC components, as well as their supports, were
consolidated in IWA-7000, and unnecessary requirements were
deleted from IWB/C/D/E/F-7000. As a result, all that remained in
IWC/D/E/F-7000 was a statement that the rules of IWA-7000 apply.
(Note that these changes were made by errata because the changes
should have been published in the 1987 Addenda.)
(e) In the 1991 Addenda, the requirements for repairs and
replacements were combined and became a new IWA-4000.
Requirements in IWB/E/F-4000 and IWA/B/C/D/E/F- 7000 were
moved to IWA-4000. The requirements for repair and replacement of Class CC concrete containments including metal liners
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Section III. Minimal requirements were included in Section XI for
performing repairs. Acknowledgment was made that replacements
may be required, but no specific requirements were included.
In 1972, preservice ultrasonic testing (UT) examinations found
flaws in a completed and stamped Section III reactor pressure vessel in the shell nozzle weld regions. These flaws were not discovered by the Section III radiography because of their location and
orientation. The discovery of these flaws led to several changes to
Section XI. Of significance to the subject of this chapter was the
identified need for requirements when Construction Code requirements could not be met (e.g., no postweld heat treatment
[PWHT]) or when the requirements were not appropriate (e.g.,
partial removal of the flaw if the remaining flaw size met the
Section XI allowable indication standards) [7].
Five specific repair procedures were added to Section XI in the
Summer 1973 Addenda as a result of the Committee work following the preservice examination discovery of flaws in the shell nozzle weld regions of the reactor pressure vessel, as discussed in the
preceding paragraph. Of significance was the addition of half
bead weld repair techniques where a controlled welding procedure is permitted without the PWHT normally required by the
Construction Code. This repair technique involved the buttering
of the exposed excavated area, the removal of one-half of the butter weld by grinding, and the completion of the repair by depositing multiple beads in a manner that tempered the previously
deposited beads and heat-affected zone to achieve the required
mechanical properties. A thermal treatment of 450-550 F for a
minimum of 2 hr completed the repair. This technique, although
revised in later Code Editions, has been of considerable industry
importance for the repair of thick-walled components whenever
the Construction Code PWHT cannot be performed practically.
Although the Summer 1973 Addenda acknowledged that
acceptance of flaws may necessitate replacement of the item containing the flaw, it did not add specific replacement requirements;
these were added in the Summer 1976 Addenda. The format of
the replacement requirements (IWA/B/C/D-7000) in the Summer
1976 Addenda and the repair requirements (IWA/B/C/D-4000) in
the 1974 Edition were significant, for no major changes in the format occurred until the 1988 Addenda.
The Impact of Differences in Plant
Construction Codes
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Of the 104 nuclear power plants currently operating in the
United States, approximately 55% have safety-related piping,
pumps, valves, and supports constructed to Codes other than
Section III. Such Construction Codes and Standards include
B31.1 and B31.7 for piping, AISC and D1.1 for supports, and the
Draft Pump and Valve Code. These older plants also may have
safety-related pressure vessels constructed to ASME Section VIII.
The remaining 45% of the plants have most safety-related pressure boundary components and systems constructed to Section III.
When combined with Owner’s Requirements and other regulatory requirements, the original Codes and Standards (hereafter
referred to as Construction Codes) used to construct a nuclear
power plant were determined by the Atomic Energy Commission
(later restructured as the USNRC or NRC) to provide an acceptable level of safety to issue a plant operating license. A key philosophy of Section XI is the referral back to the original
Construction Code and Owner’s Requirements (subject to certain
additions and limitations) for performance of repair/replacement
activities. This philosophy is appropriate because of the difficulty
and cost in trying to upgrade an existing component or system to
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intention that it would be published as a separate document for
trial use and comment. Section XI, Divisions 2 and 3 were subsequently added in the Winter 1981 Addenda, with Division 2 covering gas-cooled nuclear plants and Division 3 covering liquid
metal-cooled fast-breeder reactor nuclear plants.
(d ) IWE-4000 and IWE-7000 for repair and replacement of
Class MC metal containments and metallic shells and penetration
liners for Class CC containments were added in the Winter 1983
Addenda.
(e) IWA-4000 was revised in the 1989 Addenda to require the
Owner to have both a Repair Program, containing the managerial
and administrative controls for the completion of a repair, and a
Repair Plan, containing essential requirements for a specific
repair. The Section XI requirements in earlier addenda for the previously used term of Repair Program became part of the Repair
Plan.
(f) Requirements for repair of heat exchanger tubing by sleeving were added in the 1989 Addenda.
(g) The half bead welding requirements were replaced with
temper bead welding requirements in the 1990 Addenda.
(h) IWL-4000 for repair of concrete containments and IWL7000 for replacement of post-tensioning systems in concrete containments were added in the 1991 Addenda.
(i) Automatic and machine gas tungsten-arc welding (GTAW)
temper bead repair techniques were added in the 1991 Addenda.
(j ) The exemption for replacements NPS 1 and less was
replaced with an alternative set of requirements in the 1992
Addenda. The Owner could choose to apply the full IWA-4000
requirements to some of these previously exempted items or could
apply the alternative containing less restrictive requirements. This
change was intended to ensure that these small items functioned
as designed after replacement. The alternative does not apply to
Class 1 items larger than the safety-related reactor coolant system
makeup capability, heat exchanger tubing, and sleeves and welded
plugs used for heat exchanger tubing that must meet the full IWA4000 requirements.
(k) Beginning with the 1995 Edition, Section XI, Division 2 for
gas-cooled nuclear plants was no longer published because of the
lack of gas-cooled plants using Division 2. The 1995 Edition
referred the user to the requirements of the 1992 Edition with the
1993 Addenda for inspection and testing of gas-cooled plants.
(l ) The reformatting of IWA-4000 and use of the new term
repair/replacement activity in the 1995 Addenda, in lieu of the
previous terms of repair and replacement, significantly improved
the usability of IWA-4000.
(m) The alternative requirements for small items, previously
allowed only for replacement, was expanded in the 1995 Addenda
to include repair. Before this addenda, repair of small items was
subject to more restrictive requirements than replacements of
small items.
(n) Specific requirements for reconciliation of later Construction
Codes and later Codes other than the original Construction Code,
such as use of Section III instead of B31.1, were added in both the
1995 and 1996 Addenda. These requirements focused the reconciliation on ensuring that the hardware would satisfy design
requirements while not requiring unnecessary reconciliation of
administrative requirements.
(o) Requirements for rerating components and systems were
added in the 1995 Addenda.
(p) For repair/replacement activities involving design or
configuration changes, IWA-4000 was revised in the 1995
Addenda and the 1996 Addenda to clarify that the Owner was
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and post-tensioning systems for concrete containments were not
combined with the other repair and replacement requirements
because of the different nature of these requirements. All that
remained in Articles IWB/C/D/E/F-4000 and IWA/B/C/D/E/F7000 were statements that the rules of IWA-4000 apply. To allow
users to become familiar with this combination of IWA-4000 and
IWA-7000, these “empty” Articles were continued until their
deletion in the 1994 Addenda. In the 1998 Edition, IWE-4000
was inappropriately added back into Section XI, merely stating
that the rules of IWA-4000 apply. Because this is unnecessary and
not included in other subsections, IWE-4000 was deleted in the
2000 Addenda.
(f ) The definition of Construction Code was revised in the 1993
Addenda. It was changed from “the body of technical requirements that governed the construction of the item” to “nationally
recognized Codes . . . including designated Cases, providing construction requirements for an item.” A new term, Owner’s
Requirements, was also added to include “those technical requirements prepared by or for the Owner . . . in excess of Construction
Code requirements when a Construction Code is specified, or in
place of a Construction Code when one is not specified.” These
two definitions more accurately reflected the manner used to convey technical requirements for construction of items when the
wide age span of existing U.S. plants was considered. In addition,
they provided categorization of requirements supporting new
reconciliation requirements that were in preparation. Refer to
Section 27.5.1 for further discussion of these definitions.
(g) In the 1995 Addenda, Section XI was revised to eliminate
the previous distinction between repair and replacement. A new
term of “repair/replacement activity” was used to replace the
previous terms of “repair” and “replacement.” This term included
all activities previously identified as repair, replacement, modification,
and alteration. The revision also reorganized IWA-4000 into functional areas of general requirements; Code applicability for items;
design; welding, metal removal and installation; examination and
testing; alternative welding methods; and heat exchanger tube
plugging and sleeving. Reasons for this change are discussed in
Section 27.3.1 of this chapter.
(h) Three changes to the paragraph numbering of IWA-4400
have occurred since the IWA-4000 rewrite in the 1995 Addenda.
IWA-4400 contains requirements for welding, brazing, metal
removal, fabrication, and installation. A discussion of these
changes is contained in Section 27.10.
Important Changes in Code Requirements
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Listed below are a few of the important Section XI changes in
repair/replacement activity requirements. As noted previously,
some may be interesting from a historical perspective, and some
may be of benefit in understanding and implementing later editions and addenda.
(a) The original requirement that repair be performed in accordance with Section III was revised in the 1974 Edition to allow
repair to be performed in accordance with the original
Construction Code when requirements for that particular repair
were not specified in Section XI. The Summer 1978 Addenda further revised repair requirements to allow repair to be performed in
accordance with the original Construction Code or the special
Section XI repair provisions in IWB/C/D-4000.
(b) IWA/B/C/D-7000 replacement requirements were added in
the Summer 1976 Addenda.
(c) Section XI, Division 2 was added in the Winter 1975
Addenda and withdrawn in the Summer 1976 Addenda with the
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Footnote 1 in the preceding quotation from IWA-4110 provides
a broad list of reasons for repair/replacement activities. These reasons include discrepancies detected during ISI, maintenance, or
operation; design changes; damage from any cause; failure during
service; changes to reduce personnel exposure; changes to
improve reliability or economics; the end of life for the item; or
the addition of new items or systems.
Occasionally, a report is still received that a user improperly
concludes that Section XI’s repair and replacement requirements
apply only when a defect is found during a Section XI-required
ISI examination, or that temporary repairs can be made without
following the Section XI repair or replacement requirements. The
preceding quotation was added in response to an intent interpretation regarding the 1983 Edition of Section XI. The quotation
clearly nullifies the logic that Section XI’s repair and replacement requirements apply only when a defect is found during a
Section XI-required ISI examination. Interpretation XI-1-83-57
clarifies the issue of temporary repairs by providing Subcommittee
XI’s position on Codes as early as the Summer 1978 Addenda.
The interpretation is as follows:
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Question (1): Does the 1977 Edition of Section XI with the
Summer 1978 Addenda, or the 1980 Edition of Section XI
with the Winter 1980 Addenda, distinguish between temporary repairs and permanent repairs?
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required to revise or update Owner’s Requirements, Design
Specifications, and Design Reports. The revisions or updates were
required to be traceable to and from the original record or report
to provide a record of the current status of the item.
(q) Requirements for underwater welding of P-No.8 and P-No.
4X materials were added in the 1996 Addenda; those for underwater welding of ferritic materials were added in the 1997 Addenda.
(r) IWA-4000 provisions were revised in the 1997 Addenda to
include the addition of new systems to an existing nuclear plant.
(s) Provisions for use of repair/replacement activity leakage
tests at operating pressure in lieu of repair/ replacement activity
hydrostatic tests at elevated pressure were incorporated in the
1999 Addenda.
(t) Requirements for mechanical tube plugs in Class 1 heat
exchangers were added to the 2001 Edition of Section XI in IWA4713. No requirements were provided for Class 2 and 3 mechanical tube plugs.
(u) Beginning with the 2004 Edition of Section XI, Division 3
for liquid-metal cooled plants was no longer published because of
the lack of liquid-metal cooled plants using Division 3. The 2004
Edition referred the user to the requirements of the 2001 Edition
through the 2003 Addenda for inspection and testing of liquidmetal cooled plants.
(v) In the 2007 Edition, changes were made to the applicability
of IWA-4000 requirements to specifically include Class 2 and 3
weld tube plugs [IWA-4120(a)], and to exclude Class 2 and 3
mechanical tube plugs [IWA-4120(b)(7)] from the applicability of
IWA-4000 requirements.
Reply (1): No.
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Question (2): Is it a requirement of the 1977 Edition of
Section XI with Addenda up to and including the Summer
1978 Addenda, and the 1980 Edition with Addenda up to and
including the Winter 1981 Addenda, that repairs on components within the Class 1, 2, and 3 boundary which are not
performed in accordance with IWA-4120, IWA-4130, or IWA4200, may be made if the repairs are denoted by the Owner
as temporary and are later permanently repaired in accordance with Code rules, and if the Owner’s Quality Assurance
Program allows such temporary repairs, and if a plant evaluation is conducted allowing such temporary repairs?
SCOPE AND APPLICABILITY OF
REPAIR/REPLACEMENT ACTIVITY
REQUIREMENTS
27.3.1
When IWA-4000 Applies
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IWA-1200 defines the jurisdiction of Section XI, that is, when
the requirements of Section XI begin. Concerning repair/replacement activities, IWA-4000 applies after all of the Construction
Code requirements, including stamping, have been completed for a
component. As noted in Interpretations XI-1-98-03, XI-1-83-10,
and XI-77-15, either Section III or Section XI may be used for
repair/replacement activities in the interim after component stamping but before installation or before completion of Form N-3.
Some Section XI requirements apply only at specified times,
such as ISI NDE examinations and pressure tests. Should an Owner
perform an NDE examination for information at a time different
from a scheduled ISI examination, the requirements of Section XI
need not be applied to the performance of the examination.
However, this is not the case for the requirements for repair/
replacement activities. Although the original Section XI edition
may have only addressed repair of defects found during ISI examinations, Owners, the ASME B&PV Committee, and the NRC all
have subsequently applied these requirements regardless of the reason for performing the activity. Any time an activity covered by the
repair/replacement activities of IWA-4000 is performed, the
requirements of IWA-4000 must be met. As stated in IWA-4110(a):
The requirements of this Article apply regardless of the reason
for the repair/replacement activity [footnote 1] or the method
that detected the condition requiring the repair/replacement
activity.
Reply (2): All requirements of Section XI must be met when
making repairs to Class 1, 2, and 3 systems and components.
Question (3): Are the services of an Authorized Inspection
Agency required when making temporary repairs?
Reply (3): Section XI does not differentiate between temporary
and permanent repairs. All the requirements of Section XI,
including the use of an Authorized Inspection Agency, must be
met when making repairs to Class 1, 2, and 3 systems and
components.
It should now be clear that IWA-4000 applies at all times, during
any mode of plant operations, and for any reason that a covered
activity is performed. The next question is: What activities are covered in IWA-4000? Or, stated another way: What is a
repair/replacement activity? The need for defining terms is partly
why the term repair/replacement activity was approved to replace
the previously used terms of repair and replacement. In the 1980s,
Subcommittee XI tried to define repair, replacement, and
modification. Only the definition of repair was approved, and it was
not entirely correct without the related definitions of replacement
and modification. Subcommittee XI even tried to define maintenance with the intent that everything else would be defined as a
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removal only (no subsequent welding, brazing, or replacement activities), must the work be performed in accordance
with the provisions of IWA-4000?
Reply: No. However, if the metal removal activity affects a
previous preservice or inservice examination record, a new
preservice examination in accordance with Section XI shall
be performed and documented following the completion of
the mechanical metal removal activity.
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Two other interpretations address specific examples of metal
removal and provide Subcommittee XI’s position on whether
these examples constitute repairs and also provide guidance on
interpreting other examples. The first interpretation is XI-1-89-56,
which addresses removing weld reinforcement to enable ISI
examination. The interpretation is as follows:
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Question (1): Prior to performing a Section XI nondestructive
examination of a piping weld, it is determined that the weld
crown profile, although meeting all applicable construction/
fabrication requirements, is unsuitable for performing that
examination and must be ground to achieve the required profile. Metal removal is required, not just surface cleanup. Is
this activity a repair (IWA-4000) or a replacement (IWA7000) under the provisions of Section XI (1989 Edition with
Addenda through the 1990 Addenda)?
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repair or a replacement. Although a definition for maintenance
could not reach Committee consensus, a very useful Appendix to
Section XI was published in the 1991 Addenda. This was Appendix
J, “Guide to Plant Maintenance Activities and Section XI Repairs/
Replacements,” which is discussed later in this chapter.
After unsuccessfully attempting to define repair, replacement,
and modification, in the 1995 Addenda the Committee completely
eliminated these as separate terms, reorganized IWA-4000, and
used the new term repair/replacement activity. Reasons for this
change were (1) the need for the two different classifications of
repair and replacement was reduced with the combining of IWA4000 and IWA-7000 in the 1991 Addenda (the 1991 Addenda combined some of the previously differing requirements for repair and
replacement); (2) because much of the work and many of the
requirements for repair, replacement, and modification were similar, separate definitions and classifications did not help the user
understand and implement the requirements; (3) considerable overlaps in activities existed that made development of separate and
mutually exclusive definitions practically impossible; and (4) for
personnel implementing Section XI requirements, the rewrite eliminated problems associated with trying to classify work as repair,
replacement, or modification and instead emphasized requirements
applicable to the specific work being performed, as is done in other
B&PV Code sections.
With the use of the term repair/replacement activity, it was no
longer necessary to classify certain activities as repair, replacement, or modification; all activities that constituted a combination
of these three terms became activities covered by a repair/replacement activity. Therefore, IWA-4110(b) states that “repair/replacement activities include welding, brazing, defect removal, metal
removal by thermal means, and removing, adding, and modifying
items or systems.” This statement is concise, reasonably clear, and
readily implemented by the user. However, some clarification of
defect removal is worthwhile, because past Section XI wording
has been inconsistent and somewhat misleading regarding metal
removal activities.
Removal of defects by metal removal has always been a
Section XI repair. Section XI defines a defect as a flaw (imperfection or unintentional discontinuity) of a rejectable size, shape, orientation, location, or set of properties. But what of metal removal
activities that do not remove a defect, such as flaw removal?
Section XI defines a flaw as an imperfection or unintentional discontinuity that is detectable by nondestructive examination.
Previous Section XI repair requirements did not always use these
terms correctly, for they often used both defect removal and flaw
removal terms to describe a repair. Additionally, the term metal
removal was also used to describe a repair.
This confusion was resolved by Subcommittee XI concluding
that the appropriate way to interpret IWA-4000 requirements was
that metal removal referred to the removal of defects and that the
removal of acceptable flaws was not a repair. This opinion was subsequently supported by two approved B&PV Committee actions
that clarified the requirements: ISI 97-35/MC 98-438 and ISI 9817/BC 98-382, both of which were published in the 1999 Addenda.
Additionally, interpretation XI-1-98-20R also attempted to clarify
this position. This interpretation, which is applicable to the 1986
Edition through the 1997 Addenda, notes that flaw removal by
mechanical metal removal is not a repair and does not need to meet
IWA-4000 requirements. The interpretation is as follows:
Reply (1): No.
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Question (2): Would a Section XI NIS-2 Form be required to
document this activity?
Question: When a flaw meeting the acceptance criteria of
Section XI (i.e., not a defect) is corrected by mechanical metal
Reply (2): No.
Question (3): Prior to performing a Section XI nondestructive
examination of a piping weld, it is determined that the weld
crown profile, although meeting all applicable construction/
fabrication requirements, is unsuitable for performing that
examination and must be ground to achieve the required profile. Metal removal is required, not just surface cleanup. Is it
the intent of Section XI that the activity be considered a repair
(IWA-4000) or a replacement (IWA-7000) under the provisions of Section XI (1983 Edition with Summer 1983
Addenda)?
Reply (3): No, surface preparation for inservice inspection,
which does not encroach on required thickness, is not considered a repair or replacement.
The other interpretation is XI-1-98-08. It considers machining a
component sealing surface, such as a flange face, to remove pitting or other surface irregularities. Its applicability is the 1986
Edition through the 1995 Edition and is as follows:
Question: Is it a requirement of IWA-4100 that machining of
a pressure boundary component’s sealing surface to remove
pitting or other surface irregularity identified through normal
maintenance be considered a repair activity?
Reply: No, provided the pitting or other surface irregularity
is not a defect.
The 1999 Addenda attempted to clarify the requirements regarding metal removal and defect removal, but it still needed some
improved clarification regarding the applicability of thermal metal
removal requirements in IWA-4160. The 2001 Edition added metal
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This Article provides requirements for repair/replacement
activities associated with pressure retaining components and
their supports, including appurtenances, subassemblies, parts
of a component, core support structures, metal containments
and their integral attachments, and metallic portions of Class
CC containments and their integral attachments. . . . These
requirements are applicable to procurement, design, fabrication, installation, examination, and pressure testing of items
within the scope of this Division.
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Items Covered by IWA-4000
The wording in IWA-4110(b) gives a general identification of
items covered by IWA-4000. It states
27.3.3
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Therefore, the general identification of items included in IWA4000 includes all pressure-retaining items and their supports. Most
of the terms used in IWA-4100 are defined in the Section XI
Glossary in IWA-9000. Although a definition for “part” is not
included in IWA-9000, its meaning is standard with that used in
other ASME B&PV Code sections. A part has work performed on it
(fabrication welding) that requires inspection by an Authorized
Inspection Agency. Material is not listed in the first sentence of the
preceding quotation because it is included in each of the items listed.
The second sentence of the quotation uses the term “items,” which
appears consistently throughout IWA-4000 as an all-inclusive term.
It is defined in IWA-9000 as “a material, part, appurtenance, piping
subassembly, component, or component support.”
A nuclear power plant has many systems that are not included
in the scope of Section XI. IWA-1400(a) requires the Owner to
determine the appropriate Code Class for each component in the
plant. Except as noted in relatively recent risk-informed Code
Cases, or in the new Non-Mandatory Appendix for Risk-Informed
Inspection Requirements for Piping published in the 2005
Addenda, Section XI does not define or include the classification
criteria, but rather refers the user to the classification criteria of
the regulatory authority. For plants constructed to Section III,
most of the classification work will already have been done during construction. Of special note is the common occurrence
during plant construction where Code Class components are
installed optionally in non-safety-related, non-Code Class locations (i.e., there are no safety system criteria or Owner-licensing
commitments that require the use of Code Class items) based on
available stock at the construction site. IWA-1320(e) notes that
application of Section XI rules to these components is at the
option of the Owner and is not a requirement of Section XI.
Therefore, for these items, IWA-4000 may be used to perform
repair/replacement activities, but its use is not a requirement of
Section XI. For older plants, construction may not have included
Code Class classifications, but these older plants are required by
Section XI to classify components with ASME Code Classes for
the purpose of applying the ISI and repair/replacement activity
requirements of Section XI. Once all the components and systems
Items Not Covered by IWA-4000
IWA-4120(b) lists items excluded from the requirements of
IWA-4000. This list of exclusions is based on Section III provisions that clarify the applicability of Section III requirements.
Most of the Section III exclusions, along with Section XI
clarifications, have been included in IWA-4120(b) to assist
Owners in the application of Section XI repair/replacement activity requirements. For plants constructed to Section III, most of
these exclusions are already addressed by the IWA-4000 referral
to the Construction Code; however, for plants constructed to other
Construction Codes, such as B31.1, the list of exclusions should
prove beneficial. Items excluded from meeting IWA-4000 include
valve operators, controllers, position indicators, pump impellers,
pump drivers, and similar accessories and devices; instruments;
permanently-sealed, fluid-filled tubing systems furnished with
instruments; rupture disk material; and orifice plates connecting
piping of the same design pressure that are held in place mechanically. The 2004 Edition changed the description of orifice plates
excluded from meeting IWA-4000. Prior to the 2004 Edition,
IWA-4120(b)(4) excluded orifice plates not exceeding 12 in. nominal thickness that are used only in flow-measuring service. Some
clarifications have been included in IWA-4120(b) such as a statement noting that the portion of a rupture disk holder that forms
the pressure boundary is not excluded.
IWA-4120(b)(5) provides examples of material that are not
associated with the pressure-retaining function of a component.
Although these examples of excluded materials are helpful, they
should not be regarded as comprehensive listings. When in question, the original vendor drawings or Code Data Report will provide additional information that can be used to determine what
was included as pressure boundary material and therefore covered
by IWA-4000. IWA-4120(b)(6) provides examples of excluded
items used in component supports; again, the examples should not
be regarded as comprehensive listings.
In the 2007 Edition, IWA-4120(b)(7) was added, clarifying
Section XI requirements for Class 2 and 3 mechanical tube plugs.
The addition incorporates Section XI interpretation XI-1-04-30
and makes it clear that IWA-4000 is not applicable to Class 2 and
3 mechanical tube plugs. This same Code change also included
changes to IWA-4120(a) for Class 1 heat exchanger tube plugs
and Class 2 and 3 welded heat exchanger tube plugs as discussed
in Section 27.3.2 above. Refer to Section 27.4.1.1 for more
discussion on the history and applicability of Section XI requirements regarding heat exchanger tube plugs.
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27.3.2
have been classified by the appropriate Code Class, IWA-4120(a)
notes that the requirements of IWA-4000 apply to items classified
as Code Class 1, 2, 3, MC, or CC, as well as their associated supports, which further defines the pressure-retaining items and
supports to which IWA-4000 is applicable.
In the 2007 Edition, IWA-4120(a) was revised to clarify that
Class 1 heat exchanger tube plugs and Class 2 and 3 welded heat
exchanger tube plugs are considered pressure retaining material.
This change incorporated Section XI interpretation XI-1-07-17,
which will be published in Section XI Interpretation Volume 58.
Refer to Section 27.3.3 for the applicability of Class 2 and 3
mechanical tube plugs, which was part of this same Code revision.
As specified in IWA-4110(c), the requirements of IWA-4000
apply to repair/replacement activities performed on concrete containments and post-tensioning system items for concrete containments as specified in IWL-4000. For discussion of Subsection IWL
requirements for repair/replacement activities, see Chapter 30.
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removal by thermal means to the IWA-4110(b) list of actions
included in the term repair/replacement activities, and revised
IWA-4400 to provide more clarity for such actions. More information on the requirements for performing defect removal and metal
removal by thermal means is presented in Section 27.10.
Having discussed the meaning of repair/replacement activity
and when IWA-4000 applies, the next step is to identify the items
or systems that are covered in IWA-4000 and those that are not
covered.
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welded to the pressure boundary or component support is excluded
from meeting IWA-4000 requirements, welding makes the installation a repair/replacement activity that must meet IWA-4000.
IWA-4120(d) in the 2006 Addenda and later (IWA-4120(f)
prior to the 2006 Addenda) requires that applicable Construction
Code requirements be met for items in IWA-4120(b). In other
words, the item may be excluded from meeting IWA-4000
requirements, but the special Construction Code requirements that
apply to an item still need to be met. The intent is to ensure the
component containing the excluded items will continue to perform its design function. If the Construction Code applied some
additional provisions or controls to these items, the same provisions and controls should continue to be applied when replacing,
modifying, or adding these items, even though the items are
excluded from the rest of IWA-4000. The items, for which this
paragraph is applicable, were anticipated to be quite limited. The
examples listed come from Section III and were the only ones
identified during Committee consideration. However, they were
identified as examples, and there may be others that also apply.
The examples do indicate the type of Construction Code requirements intended to be addressed by this paragraph. The user is
responsible for identifying the requirements from the applicable
Construction Code and ensuring that these requirements are met.
27.3.4
Use of Section XI Appendix J
IWA-4120(e) in the 2006 Addenda and later (IWA-4120(g) prior
to the 2006 Addenda) notes that Appendix J provides guidance in
determining the applicability of IWA-4000. Section XI Appendix J
is titled “Guide to Plant Maintenance Activities and Section XI
Repair/Replacement Activities.” The Appendix, first added to
Section XI in the 1991 Addenda, was the result of efforts to define
maintenance activities. Because of difficulties in accurately
defining repair and replacement, it was thought that defining what
was not a repair or replacement (i.e., a maintenance activity)
would be helpful in scoping what constituted a repair or replacement. However, the preparation of any succinct definition addressing a wide range of activities proved to be difficult; defining a
maintenance activity was no exception to this difficulty. The result,
published as Non-Mandatory Appendix J, was a decision tree
(Fig. 27.1) that leads the user through a series of questions.
The decision tree has three outcomes as shown in Fig 27.1. The
first leads to the conclusion that the activity is a repair/ replacement activity (Article J-2000). The second leads to the conclusion
that the activity is a maintenance activity not within the scope of
Section XI; however, because it affects a previous required test or
examination, tests or examinations are required to be performed
after completion of the maintenance activity (Article J-3000). The
third outcome leads to the conclusion that the activity is a maintenance activity not within the scope of Section XI (Article J-4000)
to which no Section XI requirements apply.
Appendix J was added to Section XI as a Non-Mandatory
Appendix because it contained no new requirements or guidance
from those already required or intended by the Code. As such,
Fig. J-1000-1 has been widely used in the industry as guidance,
even though for several years it was not included in an edition or
addenda accepted for use by the NRC. Readers should be aware
that Fig. J-1000-1 was published incorrectly in the 1999 Addenda,
but was corrected in the 2000 Addenda.
Two clarifications regarding the wording in Fig. J-1000-1 are
noteworthy. The first involves the wording “design change” in the
middle box of the Fig. J-1000-1. The question in this box begins:
“Does activity require design change or. . . .” The “design
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In the 2006 Addenda, Section XI deleted all requirements related to the examination and testing of snubbers. As a result, IWA4120(c) and (d) were deleted and the remaining paragraphs (e)
through (g) were renumbered as (c) through (e). As discussed in
Section 27.11.2, deletion of snubber examination and testing in
Section XI does not change an Owner’s responsibility to determine when work on a snubber may require performance of snubber examination and testing as required by the ASME Code for
Operation and Maintenance of Nuclear Power Plants (OM Code)
[18], Subsection ISTD; the deletion just eliminated identification
of the Section XI interface to the OM Code requirements. To
assist users of Section XI, a footnote was added to IWA-4120(b)
noting that examination and testing requirements for snubbers and
testing requirements for pumps and valves are contained in the
OM Code. The footnote should remind users that even though
some items and activities are not addressed by Section XI, this
does not eliminate other requirements such as compliance with
the OM Code. A publishing error in the 2007 Edition included the
wrong footnote reference in IWA-4120(b), which is to be corrected in the 2008 Addenda.
IWA-4120(c) and (d) in the 2006 Addenda and later (or paragraphs (c) through (f) prior to the 2006 Addenda) provide special
conditions that must be met for items excluded by IWA-4120(b),
as discussed in the preceding paragraphs. In essence, IWA-4120(c)
and (d) in the 2006 Addenda and later (or paragraphs (c) through
(f ) when using an edition or addenda earlier than the 2006
Addenda) limit the full exclusions provided in IWA-4120(b). If
none of the conditions in IWA-4120(c) and (d) apply, then an item
in IWA-4120(b) need not meet any of the requirements in IWA4000. If one of the conditions in IWA-4120(c) and (d) apply, only
the actions provided in the applicable paragraph of IWA-4120(c)
and (d) are to be performed—that is, the rest of IWA-4000 does
not apply. The conditions of IWA-4120(c) and (d) in the 2006
Addenda and later, as well as paragraphs (c) through (f ) prior to
the 2006 Addenda, are discussed in the following paragraphs.
Prior to the 2006 Addenda, the purpose of IWA-4120(c) was to
note that although an item in IWA-4120(b) is excluded from the
rest of IWA-4000 requirements, the Owner is required to determine if the installation of the excluded item affects any inspections
or tests required by IWA-4530. The Owner’s Inservice Testing
Program would require performance of tests if any of the pump or
valve performance parameters are affected by installation of these
excluded items (refer to Section 27.11.2 for 2000 Addenda
changes associated with pump and valve testing). Likewise,
Appendix J, to be discussed in Section 27.3.4, notes that preservice examinations may need to be performed following maintenance activities that affect a previous preservice examination. As
previously noted, IWA-4120(c) was deleted in the 2006 Addenda.
Prior to the 2006 Addenda, IWA-4120(d) was similar to (c) but
addressed the specific subject of snubbers. A snubber may be
required to be examined and tested in accordance with IWF-5200
if any of the component support items in IWA-4120(b)(6) are
replaced in the snubber, even though these component support
items are excluded from the rest of IWA-4000 requirements. This
requirement was specified because of the potential for these items
and the installation process to affect the performance of the snubber. As previously noted, IWA-4120(d) was deleted in the 2006
Addenda.
IWA-4120(c) in the 2006 Addenda and later (IWA-4120(e) prior
to the 2006 Addenda) ensures that the user realizes that welding on
the pressure boundary or on a component support is an activity to
be performed in accordance with IWA-4000. Even if the item being
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FIG.27.1 APPENDIX J DECISION TREE (Source: Fig. J-1000-1 of Section XI of the ASME of the ASME BPV Code, 2004 Edition)
change” wording has been in this question since Appendix J was
first added to Section XI in the 1991 Addenda. However, the 1995
Addenda addition of design provisions in IWA-4000 led to a
request for interpretation to clarify whether “design only”
changes (i.e., no physical work performed on plant hardware) are
considered repair/replacement activities. Interpretation XI-1-01-03
concluded that the design change referred to in Appendix J was
either a design change with associated physical work on plant
hardware or a design change for rerating a component or system.
Interpretation XI-1-01-03, Question (1) has an applicability of the
1977 Edition with the 1978 Addenda through the 1995 Edition;
Question (2) has an applicability of the 1995 Edition with 1995
Addenda through the 2000 Addenda. Interpretation XI-1-01-03 is
as follows:
Question (1): Is it a requirement of IWA-4000 or IWA-7000
(as applicable) that design-only changes (i.e., no physical
work)be considered Repair, Replacement or Modification
activities?
Reply (1): No, use of the term “design change” in IWA-4000,
IWA-7000 and Appendix J only applies to activities which
involve physical work.
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Question (2): Is it a requirement of IWA-4000 that designonly changes (i.e., no physical work) except rerating be con
sidered a Repair/Replacement Activity?
applicable Construction Code. Detailed stress analysis
and consideration of secondary stress is not required.
27.4
ALTERNATIVE REQUIREMENTS
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Question: Does Section XI, IWA-7400(d), exempt piping,
valves, and fittings NPS 1 and less from the following regardless of the original Code of Construction requirements:
(a) procurement from material manufacturers or material
suppliers;
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The second clarification involves the wording “Does the material
removal activity involve . . . encroachment on required wall thickness?” that appears in the box on the right side of Fig. J-1000-1. It
may help to note that the dictionary definition of encroach is to
advance beyond desirable or normal limits. Therefore, when the
metal removal advances beyond the Code-required wall thickness
for the component, the metal removal becomes a repair/replacement activity. Admittedly, this advancement is difficult to predict in
some situations; it may necessitate a conservative initial position
that the metal removal will be a repair/replacement activity, thereby
requiring a Repair/Replacement Plan and involving the Authorized
Nuclear Inservice Inspector (ANII). If after completion of the work
the metal removal does not fall below the required wall thickness,
the Repair/Replacement Plan can always be canceled.
Changes to J-3000 were made in the 2000 Addenda associated
with the removal of Subsections IWP and IWV (Refer to Section
27.11.2 for discussion of these changes).
This exemption may have been the most misapplied in the Code.
Comments from users indicated several misapplications. For example, some Owners incorrectly interpreted the exemption as saying
that these small items could be considered non- safety-related
because there were no applicable Code requirements. Also, some
Owners incorrectly interpreted the exemption as modifying the
Owner’s license commitments regarding the applicability of committed Codes and Standards. In addition, some manufacturers were
incorrectly using the exemption to determine requirements they
used for supplying replacement items. This exemption received
numerous requests for interpretation. Some of the interpretations
contributed to the Owners’ misapplication of the exemption because
the interpretations did not note that the Owners’ licensing commitments may need to have been considered when those interpretations were applied. The interpretations issued by Subcommittee XI
noted that Section XI requirements did not apply to NPS 1 and
smaller piping, valves, and fittings, and neither did the original
Construction Code requirements when replacements for these small
items were obtained. The following two interpretations illustrate
the Subcommittee XI opinion on the application of Construction
Code requirements to NPS 1 and smaller piping, valves, and fittings.
The first Interpretation is XI-1-89-04, which follows.
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Reply (2): No, use of the term “design change” in IWA-4000
and Appendix J only applies to activities which involve physical work or rerating.
Small Items
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In the 1992 Addenda, the exemption for replacement of items
NPS 1 and smaller was replaced with alternative requirements for
small items. This revision introduced the concept of alternative
repair/replacement activity requirements not complying with all
other provisions of IWA-4000. This concept is similarly used in
other Sections of the B&PV Code and has since been used to
incorporate additional subjects. Because many Section XI Code
Cases are alternatives to the requirements of Section XI, it is
anticipated that additional alternative requirements will be added
to IWA-4130 as Code Cases are incorporated into the Code.
However, these alternatives may be moved to a Mandatory
Appendix if the number of alternatives becomes too large to reasonably manage in IWA-4130. The current alternatives are discussed in the following paragraphs.
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27.4.1.1 Background Some history on the alternative requirements of small items is first necessary to understand the basis for
these alternative requirements. From the Summer 1976 Addenda,
IWA-7400 contained an exemption for NPS 1 and smaller piping,
valves, and fittings. In the 1988 Addenda, the exemption was
clarified as including supports associated with these small items.
The exemption in IWA-7400(a) in the 1989 Edition of Section XI
reads as follows:
(a) The following items are exempt from the requirements of
this Article:
(1) gaskets;
(2) instruments;
(3) electrical conducting and insulating material;
(4) piping, valves, fittings NPS 1 and smaller, and associated supports, except that materials and primary stress
levels shall be consistent with the requirements of the
(b) Material Certification or Certificate of Compliance;
(c) third party inspection;
(d) procurement from a Certificate Holder and then stamping; and
(e) Section XI pressure testing?
Reply: Yes, to all.
The second is Interpretation XI-1-83-83 Question (3) and
Reply (3), which follows.
Question (3): May replacement piping, valves and fittings, 1
in. nominal pipe size (NPS 1) and smaller, be exempted from
Construction Code hydrostatic test requirements under IWA4310 and IWA-7400(d)?
Reply (3): Yes.
From these interpretations it is clear that Section XI is exempting NPS 1 and smaller replacement piping, valves, and fittings
from the Construction Code requirements. This conclusion was
reached because IWA-7400 exempts NPS 1 and smaller piping,
valves and fittings from all of Article IWA-7000 requirements. If
none of IWA-7000 applies, then nothing in Section XI will invoke
the Construction Code requirements. This conclusion is defensible from the wording in Section XI. However, it apparently led
some Owners to conclude that Section XI overruled commitments
to the Regulator or descriptions in their Updated Final Safety
Analysis Report. In actuality, Subcommittee XI was not taking
any position on Owners’ commitments; to do so was beyond the
scope of Section XI. Each Owner is responsible for justifying
changes in licensing commitments separate from the provisions in
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requiring these items to comply with all the requirements of IWA4000, the selective application of some of the Section XI and
Construction Code requirements should be an acceptable alternative that reasonably assures that these items will function as
designed. The alternative assures that these items are treated as
safety-related under the Owner’s Quality Assurance Program and
requires that these items be designed, furnished, and installed in
accordance with most of the original (or later) technical requirements applicable to the items. The alternative requirements require
little more than implementation of the Owner’s safety-related programs; as such, they create little hardship to Owners, yet provide
greater consistency and assurance that the items will function as
originally designed. Regarding the sizes included in the alternative
requirements, the information in the minutes noted that the alternative requirements for Class 1 are applicable to sizes that are within
normal reactor makeup capabilities operable from on-site emergency power; however, an additional limitation was applied so that
the size is not larger than NPS 1 if an NSSS design has makeup
capabilities larger than NPS 1. Because there were no similar regulatory requirements for Class 2 or 3 systems, the size for Class 2
and 3 remained NPS 1 and smaller, as stated in the exemption.
At about the same time that the aforementioned action for
deleting the exemption was in development, the use of that
exemption on heat exchanger tubing NPS 1 and smaller was identified as a concern. Section III did not exempt heat exchanger tubing, and multiple tube failures would effectively increase the
equivalent leak path to larger than the intended NPS 1 exemption.
Therefore, Subcommittee XI decided to proceed with a separate
action to exclude the use of the NPS 1 and smaller exemption on
heat exchanger tubing and also on sleeving and welded plugs used
for heat exchanger tubing. This change was included in the 1991
Addenda, one addenda before the action that deleted the exemption and included the alternative requirement provisions. It is
important to note that this change was only a clarification for
welded tube plugs and sleeves used for heat exchanger tubing, for
these were already addressed in Section XI before this change.
Section XI has included requirements for explosive welded tube
plugs since the Winter 1976 Addenda and for manual welded tube
plugs since the Summer 1977 Addenda. Also important to note is
that the location of the requirements for these welded tube plugging provisions may have been confusing, for they were added to
the repair provisions of IWB-4000 because they provided for the
repair of tubes. However, they were a modification of the original
design and, as such, would have been more appropriate in IWB7000. This matter was a source of differing opinion within the
Committee until the combination of the repair and replacement
requirements in the 1991 Addenda eliminated the debate.
Regardless of the location of the requirements, there were no
interpretations to indicate that welded tube plugs would be
exempt under the NPS 1 and smaller replacement exemption.
Interpretation XI-1-92-32, which follows, addresses the subject
of sleeving of heat exchanger tubing and notes that the Code did
not address sleeving until the 1989 Addenda. Note that it does not
mention that the NPS 1 exemption applies to sleeving.
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Because of the misinterpretations of the NPS 1 exemption,
Subcommittee XI considered action to delete or revise the exemption. Work on this action attempted to determine the technical basis
for the exemption. The generally accepted understanding of the
exemption was that it was based on the reactor coolant system makeup capability. Regulatory requirements specified makeup criteria for
Class 1 systems but lacked such criteria for Class 2 and 3 systems.
Each nuclear steam system supplier (NSSS) in the United States was
contacted to determine the Class 1 system makeup capability, operable from on-site emergency power, that would allow the reactor to be
shut down and cooled in an orderly manner as required by regulatory
requirements at that time. The results of that effort [8] showed that a
typical recent (1980s) type boiling water reactor (BWR) in the
United States had pump makeup capability to support a 34 in. NPS
pipe break. Furthermore, each of the three pressurized water reactor
(PWR) vendors in the United States also did not have pump makeup
capability to support a pipe break of up to 1 in. pipe size.
Based on this information, Subcommittee XI proposed replacing the NPS 1 and smaller exemption with alternative requirements that used less restrictive requirements than required by the
full use of IWA-4000. (These alternative requirements are discussed in Section 27.4.1.2 of this chapter). The B&PV Main
Committee minutes that contained the approved version of this
action [8] noted two reasons for the change.
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Reply (2): They apply only to the Owner.
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Question (2): Do IWA-7310 and IWA-7400(d) of Section XI,
Division 1, apply to the utility (Owner) or do they also apply
to the valve replacement part manufacturer?
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Section XI and the Section XI interpretations on these subjects.
Furthermore, as discussed in the forthcoming paragraphs,
Subcommittee XI concluded that no technical basis for part of the
exemption existed, and it replaced the exemption with different
requirements in the 1992 Addenda.
Subcommittee XI corrected the issue of manufacturers using
the IWA-7400 NPS 1 and smaller exemptions in Interpretation
X1-1-83-83 Question (2) and Reply (2), which follows. This interpretation clarifies that this exemption applied only to the Owner.
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(1) Without emergency core-cooling actuation, some Class 1
system designs do not have the capability to provide makeup
to the reactor coolant system for postulated breaks in the
NPS 1 size range. Any break of an item in the reactor coolant
pressure boundary that results in a loss of reactor coolant at
a rate in excess of the capacity of the reactor makeup system
is defined as a loss of coolant accident (LOCA). It seems
inappropriate that Section XI should completely exempt
items that, upon failure, would cause a LOCA.
(2) Small items should be designed, furnished, and installed in
accordance with requirements providing assurance that
these items will function as designed. Past WG meetings
have noted that the complete exemption of these small
items, along with supporting Section XI interpretations,
may encourage misapplication of the exemption so that the
function as designed may not be assured. It should be noted
that although Section III allows reduced requirements for
small items, it does not completely exempt them.
The information in the minutes also offered several comments
explaining the action. Instead of deleting the exemption and
Question: If a heat exchanger tube is mechanically sleeved,
and the tube is 1 NPS or less, is the replacement exempt per
Section XI, IWA-7400(d) except that materials and primary
stress levels shall be consistent with the requirements of the
applicable Construction Code?
Reply: Section XI did not address mechanical sleeving in the
1986 Edition. [Note: Starting with the 1989 Addenda,
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Reply: Yes.
Question: May the repairs performed on piping, valves,
fittings, NPS 1 and smaller, and associated supports, be
exempt from the requirements of IWA-4000, provided that the
materials and primary stress levels are consistent with the
requirements of the applicable Construction Code?
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Mechanical tube plugs continued to be exempt from repair/
replacement activities under Section XI requirements prior to the
1992 Addenda when the alternative requirements for small items
replaced the exemption for NPS 1 and smaller items. From the
1992 Addenda up through the 2006 Addenda, there were no
exemptions specifically applicable to mechanical tube plugs. The
alternative requirements discussed in Section 27.4.1.2 were able to
be used for mechanical tube plugs, but it was not clear what provisions were required for mechanical tube plugs if the alternatives of
IWA-4131 were not used. However, in the 2001 Edition, Section
XI was revised to add IWA-4713 containing new requirements for
Class 1 mechanical tube plugs. These requirements standardized
the provisions for Class 1 mechanical tube plugs and will assure
that all plugs used in the industry meet a consistent set of requirements. Class 2 and 3 mechanical tube plugs were not addressed by
this Code change and can still be addressed under the IWA-4131
alternative requirements for small items. As noted above, it was
not clear what requirements applied to Class 2 and 3 mechanical
tube plugs if the alternative requirements were not used.
This issue of Class 2 and 3 mechanical tube plugs was finally
clarified in 2005 with the approval of Inquiry IN05-14 (published
as Interpretation XI-1-04-30). Due to an error, an approved accompanying question was not published in Interpretation XI-1-04-30.
The Section XI approved questions and replies were as follows:
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Question: If a heat exchanger tube is mechanically plugged,
and the tube is 1 NPS or less, is the replacement exempt per
IWA-7400(d) except that materials and primary stress levels
shall be consistent with the requirements of the applicable
Construction Codes?
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The position taken in Interpretation XI-1-92-32 superseded the
previous Interpretation XI-1-86-41, which had indicated that
sleeving of heat exchanger tubing by contact rolling was exempt
under the provisions of IWA-7000.
Interpretation XI-1-92-44, which follows, provides some additional clarification regarding application of the repair and replacement requirements of Section XI to heat exchanger tubing. It
notes that a mechanical tube plug used in heat exchanger tubing is
exempt under the NPS 1 and smaller provisions.
including the 2006 Addenda. A related intent inquiry regarding
material for Class 1 mechanical tube plugs, initially part of
Inquiry IN05-14, was approved as interpretation XI-1-07-17 and
will be published in Interpretation Volume 58. The accompanying
Code change incorporating the intent into IWA-4120(a) was
approved and published in the 2007 Edition of Section XI and is
discussed in Section 27.3.2.
The preceding discussion on the exemption for replacement of
NPS 1 and smaller items should be carefully considered by
Owners using editions and addenda published before the 1992
Addenda, when the exemption was replaced by alternative
requirements for small items. Before discussing the current
requirements for small items, some additional comments are provided in the forthcoming paragraphs regarding the replacement
exemption for NPS 1 and smaller piping, valves, and fittings.
The preceding discussion did not mention the repair of NPS 1
and smaller items, because the exemption never covered repairs.
The exemption was initially in IWA-7000, which covered replacement. When the IWA-4000 and IWA-7000 Articles were combined in the 1991 Addenda, the exemption was moved to IWA4120, although it still addressed only replacement. Interpretation
XI-1-92-68, which follows, clarified that repair of NPS 1 and
smaller items was not exempt. It applied to the 1980 Edition
through the 1990 Addenda.
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sleeving rules were incorporated into Section XI, IWB-4300
(and were moved to IWA-4420 in the 1991 Addenda). In the
1991 Addenda, IWA-4120 further clarified that the NPS 1
exemption does not apply to heat exchanger sleeves.]
Question (1): Does IWA-4000 address mechanically installed
heat exchanger tube plug assemblies? (Applicability: 1992
Addenda up to and including the 2000 Addenda).
Reply (1): No
Question (2): Does IWA-4000 address Class 2 and 3 mechanically installed heat exchanger tube plug assemblies?
(Applicability: 2001 Edition up to and including the 2005
Addenda).
Reply (1): No
A revision to XI-1-04-30 is expected to be issued to correct this
error as well as extend the applicability of Question (2) up to and
Reply: No.
For the time frame beginning with the the 1992 Addenda, when
the alternative requirements replaced the exemption, Interpretation
XI-1-92-60, which follows, also clarified that repairs were not covered by the alternative requirements.
Question: Does Section XI, IWA-4120(a) exempt “repairs” of
the listed items?
Reply: No.
Subcommittee XI concluded in a later action that there was no
technical basis for the inconsistent way in which repair and replacement were treated. In the 1995 Addenda, the alternative requirements for small items (IWA-4130) were revised to include repairs—
a change that may be somewhat difficult to identify because the
1995 Addenda changed terminology from “repair and replacement”
to “repair/replacement activities.” In addition, an error in the printing
of the 1995 Addenda in IWA-4131 incorrectly indicated IWA-4131
as applicable only when items were replaced. In the 1995 Addenda,
IWA-4131 began with the wording “When repair/replacement activities involve replacing the following items. . . .” The word “replacing” was deleted by errata in the 1996 Addenda. Code Case N-544,
“Repair/Replacement of Small Items,” was issued to allow the alternative requirements for repair and replacement of small items to be
used before use of the 1995 Addenda.
Another question that is commonly asked about the IWA-7400
exemption of NPS 1 and smaller piping, valves, and fittings concerns the connection weld of an exempt item to a larger item that
is not exempt. Interpretation XI-1-92-66, which follows, answers
this question.
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Reply: Yes.
Even though most requirements of Section XI have been interpreted as not being applicable for replacement of these smaller
items, Interpretation XI-1-89-36, which follows, does note that
testing requirements of Subsection IWV are applicable even if the
replacement requirements of IWA-7000 are exempted.
Reply (1): Yes; however, if testing is required by IWV-1000,
this testing shall be conducted, even if a replacement program
is not required.
27.4.2
IWA-4132 was added in the 1996 Addenda as an incorporation
of Code Case N-508-1. It is standard practice for many Owners to
have spare snubbers and pressure relief valves in stock, that is, in
their available plant storage or warehouse inventory. These instock items will be rotated into installed plant locations to replace
currently installed snubbers and relief valves. The purpose of this
rotation is to facilitate testing required by the Owner’s Inservice
Testing Program. By removing an item and installing a replacement item that is fully tested and ready for service, the Owner can
reduce the out-of-service time for a plant system to the time
required only for the change of the item.
Before the approval of the Code Case or the addition of
IWA-4132, the Owner needed to complete a Repair/Replacement
Plan and a Form NIS-2 to document the activity of replacing each
snubber and pressure relief valve. This could necessitate dozens
of Repair/Replacement Plans and NIS-2 Forms in a normal refueling cycle and as many as several hundred if the Inservice
Testing Program required sample expansion. Subcommittee XI
determined that these administrative requirements were not necessary if the conditions in IWA-4132 were met. The administrative
tracking accomplished by the Form NIS-2 was replaced with a
requirement for the Owner to track item locations and to ensure
traceability of the inservice inspection and testing records to a
specific snubber or pressure relief valve.
Most of the requirements of IWA-4132 are clear, but one requirement warrants comment. IWA-4132(d) notes that items previously
will have been in service. The purpose of this requirement is to
ensure that each item has undergone the Code-required reviews that
are performed whenever an item is newly installed, such as ensuring that the item meets both the Owner’s Requirements and the
Construction Code requirements in addition to ensuring that the
item receives appropriate ANII review and inspection.
Several changes have been made to IWA-4132 since the first
edition of this book. Changes were made to IWA-4132(h) in the
2000 Addenda associated with the removal of Subsection IWV
(see Section 27.11.2 for discussion of these changes). Changes
were made in the 2001 Edition to delete the requirement in IWA4132(e) to perform a pressure test and VT-2 following installation
of a replacement relief valve. This parallels the previous change
in the 1999 Addenda to delete the IWA-4540(c) requirement to
perform a pressure test and VT-2 examination of mechanical
joints made in installation of pressure-retaining replacement items
(this previous change is discussed in Section 27.11.3.1). The 2001
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Reply (2): Yes; however, if testing is required by IWV-1000,
this testing shall be conducted, even if a replacement program
is not required.
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Now that the background of the alternative requirements for
small items has been reviewed, the actual requirements in IWA4131 are provided in the following discussion.
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27.4.1.2 Implementation of the Alternative Requirements
for Small Items IWA-4131.1 describes the items that may use the
alternative requirements for small items. The basis for the sizes in
IWA-4131.1 were described in the previous section on the background for the alternative requirements.
IWA-4131.2(a) provides the alternative requirements that may be
used to obtain these small items. It was the intent of Subcommittee
XI that these small items continue to function as designed by
requiring that the items meet the technical requirements of the original Construction Code or other acceptable Construction Code
requirements as allowed and reconciled by IWA-4200, and also by
requiring that the items be obtained under the provisions of an
acceptable Quality Assurance (QA) Program. The original
Construction Code quality and administrative requirements need
not be met for these small items. Additionally, IWA-4131.2(a)
notes that if the Repair/Replacement Organization constructs or
fabricates the item, a Repair/Replacement Plan is not required.
IWA-4131.2(b) addresses the typical repair/replacement activities of welding, brazing, defect removal, fabrication, installation,
and examination. It requires that the repair/replacement activities
meet the technical requirements of IWA-4400 and IWA-4520 and
be performed in accordance with a QA Program. It excludes a
Repair/Replacement Plan, pressure testing, services of an
Authorized Inspection Agency, and completion of Form NIS-2,
just as provided by the original IWA-7400 exemption.
IWA-4131.2(c) requires that corrective action be taken to determine the cause of item failure consistent with the corrective action
provisions of the Owner’s QA Program. Changes were made to
IWA-4131.2(d) in the 2000 Addenda to require that IWA-4530(b)
requirements be met for an item that affects a snubber performance
parameter. IWA-4131.2(d) was deleted and the remaining paragraph
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Alternative Requirements for Snubbers and
Relief Valves
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Question (2): Does Section XI, IWA-7400(a)(4) exempt valve
replacements NPS-1 and less from the preservice test requirements of IWA-7530(b)?
AS
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Question (1): Does Section XI, IWA-7400(a)(1) exempt gasket
replacements from the preservice test requirements of IWA7530(b)?
(e) renumbered to (d) in the 2006 Addenda when snubber examination and testing provisions were deleted from Section XI. See
Section 27.11.2 for discussion of the changes.
In essence, IWA-4131.2 has these small items treated much like
other safety-related items in the plant, but without most of the
typical Code administrative requirements. It should not produce
much more work than what an Owner would typically do for a
safety-related, non-Code item. To assure clear use of these alternative requirements for small items, IWA-4131.2(d) in the 2006
Addenda and later (previously IWA-4131.2(e) prior to the 2006
Addenda) requires that the Owner document in the Repair/
Replacement Program how these alternative requirements will be
implemented, including the size of Class 1 items to which these
requirements will be applied. This will assure that the ANII
knows how the alternative requirements are being implemented
and is able to identify items that do not require ANII verification.
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Question: When a component connection, NPS 1 and smaller,
is welded to a pipe or component greater than NPS 1, does
the attachment weld to the larger pipe or component fall
under the same exemption as stated in IWA-7400(d)?
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Main Committee minutes when Code Case N-523 was approved,
mechanical clamping devices were not previously prohibited by
the provisions of Section XI. However, Subcommittee XI concluded that a Case providing industry consensus standards to be
used for mechanical clamping devices was desirable. The provisions of IWA-4133 now make Appendix IX of Section XI mandatory when using a mechanical clamping device to replace the
pressure boundary of degraded piping. Fabrication and installation of a mechanical clamping device is a repair/replacement
activity and is documented as any other repair/replacement activity, except that the Repair/Replacement Plan also needs to identify
the defect characterization method, design requirements, and
monitoring requirements in accordance with the requirements of
Appendix IX.
Appendix IX contains several limitations on the use of a
mechanical clamping device. Mechanical clamping devices may
be used only on piping and tubing and their associated fittings and
flanges, as well as the welding ends of pumps, valves, and pressure vessels. When used, a mechanical clamping device is acceptable only until the next refueling outage, at which time the defect
in the piping has to be removed or reduced to an acceptable size
through a repair/replacement activity. Mechanical clamping
devices may not be used on Class 1 items, any portion of a piping
system that forms part of the containment boundary, high-energy
piping larger than NPS 2, or any piping larger than NPS 6.
Specific requirements for defect characterization, design, materials, pressure testing, and monitoring of defect growth and leakage are contained in Appendix IX and will not be duplicated here.
However, one clarification is worthwhile to mention regarding
material requirements. IX-4000 is rather brief and simply states
that material shall meet the technical requirements of IWA-4220
and shall be furnished with Certified Material Test Reports. In
other words, when the original Construction Code is Section III,
the material does not need to meet the NCA-3800 administrative
requirements that necessitate the involvement of an N-Type
Certificate Holder or Quality System Certificate Holder. However,
the material does need to meet the requirements of NX-2000 and
be furnished in accordance with a Quality Assurance Program
that conforms to IWA-4142.
For Owners using Code Case N-523-1, interpretation XI-1-01-17
may be useful. It is as follows.
Alternative Requirements Involving
Mechanical Clamping Devices
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Edition changes also removed the involvement of the ANII in use
of the IWA-4132 alternative and clarified that no other requirements of IWA-4000 apply when using the IWA-4132 alternative
requirements.
In response to additional questions regarding the involvement
of the ANII in IWA-4132 activities, Interpretation XI-1-07-16
clarified that the use of an ANII was not required for any IWA4132 specified preservice inspections or pressure tests for any edition or addenda containing IWA-4132. Interpretation XI-1-07-06
provided similar clarification for Code Cases N-508 and subsequent versions through N-508-3.
The 2004 Edition revised IWA-4132 to include rotation of snubbers and pressure relief valves for the purpose of preventive maintenance reasons in addition to the previously included purpose of
testing. Removal for preventive maintenance activities such as seal
replacement due to service life limitations was consistent with the
concept of allowing some activities without the administrative overhead of Repair/Replacement Plans, NIS-2 Forms and ANII involvement. The revision also clarified that any repair/replacement activities performed on the snubber or relief valve while it was removed
must meet all requirements of IWA-4000. Unfortunately, due to
publishing errors the 2004 Summary of Changes (in the front of the
2004 Edition of Section XI) and the margin at paragraph IWA-4132
did not identify that changes were made to IWA-4132 and users
may not realize these important changes have been made!
Interpretation XI-1-04-23 clarified that Code Cases N-508, N-508-1,
and N-508-2 only addressed rotation of snubbers and relief valves
for the purpose of testing and did not include rotation for the purpose of preventive maintenance. However, rotation for the purpose
of preventive maintenance was included in Code Case N-508-3 and
should be considered by Owners working to an edition or addenda
earlier than the 2004 Edition.
IWA-4132 was revised in the 2006 Addenda to delete the paragraph on snubber testing when snubber examination and testing
were deleted from Section XI (see Section 27.11.2 for discussion
of these changes).
As a clarification to remove potential confusion, IWA-4132 was
revised again in the 2007 Edition to delete the paragraph on preservice inspections. Since the 2006 Addenda deleted snubber
examination and testing provisions from Section XI, there are no
preservice inspection or testing requirements applicable to IWA4132 items, which are installed by mechanical means.
PR
IWA-4133 and Appendix IX were added in the 1997 Addenda
to incorporate Code Case N-523-1. N-523-2 included paragraph
number revisions to match changes in Section XI and should be
considered for use by Owners using earlier editions and addenda.
Cases N-523-1 and N-523-2 have been annulled by ASME and
are both listed in Regulatory Guide 1.147 [17] as annulled. This
means an Owner can no longer adopt either Case for use but may
continue to use a Case until the end of the interval if the Case was
adopted prior to being listed in the Regulatory Guide as annulled.
The 1997 change provided provisions for the temporary use of
a mechanical clamping device to replace the pressure boundary of
degraded piping. Use of a mechanical clamping device can be
very beneficial by reestablishing the pressure boundary integrity
of degraded piping within the allowed out-of-service time limits
of the plant Technical Specifications when draining of the system
associated with a typical welded repair/replacement activity cannot be accomplished within the time limit. As noted in the B&PV
Question: Is it the intent of Code Case N-523-1 to allow the
use of other Editions and Addenda of ASME Section XI (e.g.,
1989 Edition) provided the corresponding paragraph numbers are used?
Reply: Yes.
27.4.4
Alternative Requirements for Purchase,
Exchange, or Transfer of Materials
Alternative provisions for Owners to purchase, exchange, or
transfer materials between nuclear plant sites were added in the
2006 Addenda as a new paragraph IWA-4134. These alternative
provisions incorporate Code Case N-528-1 and may be valuable
to plants built to ASME Section III because Section XI requires
that some Construction Code requirements such as NA-3700/
NCA-3800 be met (as discussed in Section 27.8.2). The alternative provisions require some portions of NA-3700/NCA-3800 to
be met but allow an Owner to accept material without qualification of the supplying Owner to the requirements of NA-3700/
NCA-3800.
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27.5.1
Owner’s Responsibilities
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IWA-4141 identifies some of the Owner’s specific responsibilities. The Owner is to provide or cause to be provided (i.e., the
Owner can subcontract preparation) the Repair/Replacement
Program, Repair/Replacement Plan, and the specification requirements for repair/replacement activities. (The Repair/Replacement
Program and Repair/Replacement Plan are discussed at length
later in this chapter, so therefore they will not be discussed here.)
Specification requirements for repair/replacement activities refer
to the Owner’s Requirements and Construction Code(s) that provide the complete basis for construction of an existing item,
including changes since construction, or the Owner’s
Requirements and Construction Code for a replacement item.
These specification requirements are the beginning point for all
repair/replacement activities. It is the Owner’s responsibility to
maintain these requirements and provide them to the
Repair/Replacement Organization.
This discussion uses the term Owner’s Requirements, a new
term for Owners working with Section XI editions and addenda
earlier than the 1993 Addenda. It is used repeatedly throughout
IWA-4000, normally in conjunction with Construction Code. This
new term was added to include “those technical requirements prepared by or for the Owner . . . in excess of Construction Code
requirements when a Construction Code is specified, or in place
of a Construction Code when one is not specified.” The definition
of Construction Code was also changed from “the body of technical requirements that governed the construction of the item” to
“nationally recognized Codes . . . including designated Cases,
providing construction requirements for an item.” The 2001
Edition revised the definition of Owner’s Requirements to more
clearly define its content and to include both technical and administrative requirements. These two definitions more accurately
reflect the manner used, in the wide age span of existing plants in
the United States, to convey requirements for construction and
installation of items. Owner’s Requirements include not only a
Section III Design Specification (which would be the better term
to use if all plants were built to Section III), but also the purchase
order requirements used in some older plants to convey similar
requirements.
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There are two organizations identified in IWA-4000 that may
perform repair/replacement activities: the Owner and the
Repair/Replacement Organization. The Owner is the organization
legally responsible for the construction and/or operation of the
nuclear facility, whereas the Repair/Replacement Organization is
the organization that performs the repair/replacement activity. As
noted in the definition of the Repair/Replacement Organization in
IWA-9000, the Owner may be the Repair/Replacement Organization
when the Owner performs the repair/replacement activity. Most of
the requirements in IWA-4000 do not specifically identify the
responsible organization, but in general they refer to the organization performing the repair/replacement activity. However, IWA4140 identifies specific responsibilities for these organizations
that one must be cognizant of when the requirements elsewhere in
IWA-4000 are read.
for what was required by NRC Regulations and Owner’s QA
Programs. It requires a Repair/Replacement Organization to
establish a QA Program for control of its repair/replacement
activities. When the Owner is the Repair/Replacement
Organization, the QA Program is to be in accordance with IWA1400(n), which requires compliance with either U.S. Federal
Regulation 10CFR50, Appendix B, or ASME Standard NQA-1.
When the Repair/Replacement Organization is anything other
than the Owner, three options are available: the QA Program criteria of 10CFR50, Appendix B, supplemented as necessary to be
consistent with the Owner’s QA Program; NQA-1, Parts II and
III; or a Section III NCA-4000 QA Program.
It should be noted that IWA-1400(q) was added in the 2007
Edition to allow electronic certification, authorization, and approval
of records. IWA-1400(q), if utilized, requires these provisions to be
described in the QA Program required by IWA-1400(n). The addition of IWA-1400(q) was intended to be part of a broader Boiler
and Pressure Vessel Committee action included in the 2006
Addenda to address methods other than written signatures for certification/approval of records. The changes made to IWA-4440(b) in
the 2006 Addenda (see Section 27.10.5 for discussion) and the
addition of IWA-1400(q) in the 2007 Edition completed the Section
XI changes associated with the broader BPVC action.
Alternative QA Program provisions for Owners to perform certain Section III NA-3700/NCA-3800 material procurement and
acceptance activities were added in the 2007 Edition as a new
IWA-4142.1. These alternative provisions incorporate Code Case
N-517-1 and may be valuable for plants built to ASME Section
III, as discussed in Section 27.8.2. As part of this 2007 Edition
change, several new definitions were added to IWA-9000, similar
to those contained in Section III NCA-9000.
For Owners in the United States, the provisions of IWA-4142
were modified by a limitation in Federal Regulation 10CFR
50.55a(b)(2)(x), effective November 22, 1999. The limitation
notes that the 1989 Edition of NQA-1 is acceptable “if the
licensee uses its 10CFR Part50, Appendix B quality assurance
program, in conjunction with Section XI requirements.
Commitments contained in the licensee’s quality assurance program description that are more stringent than those contained in
NQA-1 must govern Section XI activities. Further, where NQA-1
and Section XI do not address the commitments contained in the
licensee’s Appendix B quality assurance program description, the
commitments must be applied to Section XI activities” [9].
Owners in the United States, as well as Repair/Replacement
Organizations working in the United States, are affected by this
regulation change and will need to consider this limitation when
developing and applying their QA Programs to Section XI activities. For most Owners in the United States, this change will have
little impact on their performance of repair/replacement activities
because their QA Program and reductions to it are approved by
the NRC. However, the change may affect Repair/Replacement
Organizations and Owners’ approval of Repair/Replacement
Organizations’ QA Programs. The supplemental information in
the Federal Register publication of the final rule, effective
November 22, 1999, further explains this limitation and clarifies
the NRC’s intent regarding QA Programs, even for Owners
implementing the then approved 1989 Edition or earlier editions
of Section XI [10].
The Repair/Replacement Organization’s QA Program is
required to be reviewed and accepted by the Owner and to be of
sufficient detail for the Owner to determine that the requirements
of IWA-4000 will be met. At first reading, the definition of
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RESPONSIBILITIES
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27.5
27.5.2
Quality Assurance Program Responsibilities
Paragraph IWA-4142, which requires the Repair/Replacement
Organization to have a QA Program, was added in the 1993
Addenda (IWA-4132 at that time) to provide a Code requirement
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Reply: Yes.
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Question: Does IWA-4000 (or IWA-7000, as applicable) permit an Owner to contract repair/replacement activities to be
controlled in accordance with the Owner-approved Quality
Assurance Program of the contractor (Repair/Replacement
Organization), with ANII services to be subcontracted by the
Repair/Replacement Organization and a Data Report to be
prepared and certified by the Repair/Replacement
Organization and the subcontracted ANII certifying that the
applicable requirements of Section XI have been met?
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Interpretation XI-1-95-09, which follows, also addresses part
of this subject.
AS
Question (1): When a vendor performs off-site Section XI
repair/replacement activities (e.g., repair welding) on existing
plant equipment which has been removed with the intention of
reinstallation, and further Section XI repair/replacement
activities (e.g., nondestructive examination or hydrostatic testing) will be performed by the Owner prior to or concurrent
with reinstallation, is the Owner responsible for imposing
Section XI requirements on the vendor?
Y
Reply (1): Yes.
Question (2): When a vendor performs repair/replacement
activities off-site on removed plant equipment and further
repair/replacement activities by the Owner or repair organization prior to reinstallation of the item will not be required,
is the Owner responsible for imposing Section XI requirements on the vendor?
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Repair/Replacement Organization in IWA-9000, which notes that
this organization performs repair/replacement activities under the
provisions of the Owner’s Quality Assurance Program requirements, seems to conflict with the requirements of IWA-4142.
However, the definition is merely addressing the Owner’s overall
responsibility, for the Owner is legally responsible for the plant
and all of the work performed. Even work that is subcontracted to
a Repair/Replacement Organization is ultimately under the overall
provisions of the Owner’s QA Program.
Because of the manner in which the repair/replacement activity
work may be divided between an Owner and a Repair/
Replacement Organization, considerable confusion can exist
regarding which QA Program will govern the specific performance
of certain activities. IWA-4142(b) notes that it is the Owner’s
responsibility to establish the interfaces of each organization’s QA
Program and work activities and for assuring that the requirements
of IWA-4000 are met for the combination of the QA Programs.
For example, the Owner usually requires that the Repair/
Replacement Organization use the Owner’s work control processes
to assure proper control of work in the plant. Additionally, the
Owner may provide inspection and examination services to the
Repair/Replacement Organization and may perform the pressure
tests following the repair/replacement activity. It is essential that
these interfaces be worked out during the Owner’s review and
approval of the Repair/Replacement Organization’s QA Program,
procedures, and specific work documents.
From the preceding discussion and the requirements of IWA4142, one essential condition for a Repair/Replacement
Organization is that it establish a QA Program and perform the
repair/replacement activity under the provisions of that QA
Program. Sometimes an organization provides personnel and
equipment for performing a repair/replacement activity, but does
not perform any of the work under the provisions of its QA
Program—that is, the work is performed entirely under the control of the Owner’s QA Program. In this situation, the organization is not a Repair/Replacement Organization but merely
provides labor and non-plant equipment for use by the Owner. In
this case, the Owner is the Repair/Replacement Organization and
is responsible for assuring that the requirements of IWA-4000 are
met, including the completion of Form NIS-2 that certifies the
work to Section XI requirements.
When the Owner sends an item off-site for performance of a
repair/replacement activity, the Owner is responsible for invoking the requirements of Section XI, IWA-4000, on the vendor
and for assuring that the interfaces are clearly defined regarding
what portions of the repair/replacement activity are to be performed by the vendor under its QA Program and what portions
are to be performed by the Owner. Because some vendors may
not be accustomed to working to Section XI requirements, the
Owner needs to clearly identify the jurisdiction of Section XI
and the requirements of IWA-4000 for performing the
repair/replacement activity. The Repair/Replacement Plan
becomes a good communication tool for identifying many of
these requirements to the vendor.
Two interpretations on this subject are noteworthy and provide
information regarding subcontracting repair/replacement activities
to off-site organizations. Interpretation XI-1-98-62, which follows, notes that the Owner can contract repair/replacement activities to be performed by a contractor or vendor who becomes the
Repair/Replacement Organization and completes the Section XI
requirements including the applicable Data Report form for the
work performed:
Reply (2): Yes, for items removed from systems which have
been placed in operation, see Interpretation XI-1-83-10.
Reply (2), by reference to Interpretation XI-1-83-10, notes
that there is an exception to the requirement of imposing Section
XI. This exception is when the vendor is the original manufacturer and will perform the work under the jurisdiction of Section
III and provide a modified Section III Code Data Report. As
noted in Interpretations XI-1-98-03 and XI-1-83-10, either
Section III or Section XI may be used for repair/replacement
activities after component stamping but before installation, or
before completion of Form N-3, or before plant operation when
Form N-3 is not used. Other than this exception, the vendor is to
perform the repair/replacement activity to the requirements of
Section XI within the scope and interfaces established by the
Owner.
27.5.3
Stamping
Since the requirements for replacements were added to Section
XI in the Summer 1976 Addenda, IWA-7000 included a provision
that application of the Section III NA Symbol Stamp was neither
required nor prohibited for installation of replacements. This
provision was renumbered IWA-4920 with the combination of
IWA-4000 and IWA-7000 in the 1991 Addenda, and IWA-4143 in
the 1995 Addenda as part of the rewrite of IWA-4000, but the
content remained essentially the same. The intent was to clarify
that neither the Owner nor the Repair/Replacement Organization
had to possess an NA Certificate of Authorization to install
replacement items. Interpretation XI-81-11R, which follows,
further clarified the issue of whether an NA Stamp was required
for performing repairs or replacements.
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Question (1): Is it a requirement of Section XI, Division 1,
that organizations performing repairs, installations, or
replacements, or any combination thereof, of Code stamped
nuclear components be a holder of an ASME NA Certificate
of Authorization?
Reply (1): Section XI, Division 1, does not require an organization performing repairs, installations, or replacements, or
any combination thereof, to have an ASME NA Certificate of
Authorization.
Application of the ASME NPT symbol is neither required nor
prohibited for the fabrication of parts, appurtenances, piping
subassemblies, and supports to be used by the Owner when
performed at the Owner’s facilities by a Repair/Replacement
Organization with a quality assurance program that complies
with IWA-4142. These provisions may not be used to manufacture complete pumps, valves, vessels, or tanks.
TA
Question (2): Does Section XI require organizations that perform repair work to be certified by ASME?
R
Interpretation XI-80-07 Question (2) and Reply (2), which follows, addresses only the question of repairs and makes clear the
fact that no ASME Certificate of Authorization is required to perform repairs.
Y
Reply (2): Section XI, Division 1, does not require an organization performing repair work to be a holder of National
Board NR Certification. However, the requirements of state or
local authorities, or the Owner may make National Board NR
Certification a requirement for organizations that perform
repair work.
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Question (2): Is it a requirement of Section XI, Division 1,
that an organization performing repairs, or replacements, or
any combination thereof, of Code stamped nuclear components be a holder of National Board NR Certification?
As a result, the original Section XI concept continues today - that
is, an Owner should be allowed to accept responsibility for the
maintenance of a power plant without any type of ASME assessment program for Section XI activities.
A significant addition to IWA-4143 was made in the 1997
Addenda: the recognition, as part of Section XI installation activities, of the standard industry practice of Owners preassembling
piping materials to make piping spool pieces. This practice had
been used widely to make as many welds as possible in plant shop
facilities, where conditions foster the economical production of
high-quality welds that minimize the number of, and the radiation
exposure associated with, in-plant installation welds. This practice had typically considered preassembly of piping materials to
be part of the Section XI installation process. This, however,
hadn’t been supported by some older ASME interpretations; these
indicated that preassembly of piping materials must be done in
accordance with the Construction Code, which for plants constructed to Section III would require an NPT Certificate of
Authorization. As noted in the Committee action to revise IWA4143, it is acceptable for an Owner to install the equivalent of a
piping subassembly by installing multiple pieces of piping material (e.g., a pipe or a fitting) one piece at a time in the plant. If this
piece by piece assembly process in the plant is acceptable, preassembly of the spool piece in the plant shop should certainly be
acceptable. The approved addition to IWA-4143 clarified the
Subcommittee XI position on Owners fabricating piping subassemblies. IWA-4143(a) states the following:
IE
Reply (2): Section XI does not require an organization performing repair work to be certified. However, the Owner must
verify that the repair program meets the requirements specified in Article IWA-4000.
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In the late 1970s and again in the late 1980s, Subcommittee XI
considered whether an ASME certification program for performing
repair and replacement should be required. At both times, such a
proposed program failed to obtain the necessary consensus for
approval. Section XI began with the concept that an Owner should
be allowed to accept responsibility for the work that an Owner must
perform to maintain a power plant without becoming an ASME NType Certificate Holder. It recognizes that there are significant differences between new construction and operating and maintaining a
nuclear power plant. Under Section III requirements, N-Type
Certificate Holders construct and install components but have no
continuing responsibility for these items or the plant. The ASME
Certificates and the ASME surveys that determine the compliance
of an organization to the applicable ASME Code assure the purchaser of the quality of the product at delivery. All of ASME’s conformity assessment programs assure the quality of newly constructed items. ASME’s conformity assessment programs have not
entered into assessing the end user’s compliance in maintaining
components. In contrast, the Owner is the end user and is legally
responsible for maintaining the nuclear plant and protecting the
health and safety of the public. The Owner is charged with the
responsibility of Code compliance and has independent inspections
performed by the Authorized Nuclear Inservice Inspector. The
Owner’s compliance is assessed semiannually by the Authorized
Nuclear Inservice Inspector Supervisor and on a continuing basis
by the regulatory authority (in the United States, the NRC). In addition, some enforcement authorities (in the United States, states or
municipalities) have involvement in assessing Owner compliance.
As can be seen from this change, it addresses the fabrication of
parts (including but not limited to piping subassemblies and supports) and appurtenances, but excludes construction of components, such as pumps, valves, vessels, and tanks. This change
allowed Owners working to the 1997 Addenda, as well as to later
editions and addenda, to fabricate parts for use in existing plant
components, such as pumps and valves. This may be quite
beneficial for quickly returning items to service when the replacement parts cannot be obtained in a timely fashion or when original manufacturers have either gone out of business or dropped
their ASME N-Type stamp.
Unfortunately, the changes to IWA-4000 to clarify how fabrication, as approved in IWA-4143, was to be integrated into the rest of
the repair/replacement activity requirements were not published
until the 2005 Addenda. For the interim, for piping subassemblies,
Subcommittee XI clarified that the joining of items in the Owner’s
or Repair/Replacement Organization’s fabrication shop can be
included in the term “installation,” as used in IWA-4000. This
clarification is provided in Interpretation XI-1-98-61, which follows:
Question: Does the Section XI term “installation” allow the
joining of items, by the Owner or Repair/Replacement
Organization into a piping subassembly, at a location other
than its final location in the piping system?
Reply: Yes.
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Program as a specific procedure if it contains the managerial and
administrative control for the completion of repair/replacement
activities. The Repair/Replacement Program may involve more
than one procedure or document, but the interface and control
should be clearly provided when multiple documents are used.
IWA-4000 does require that the Repair/Replacement Program
contain three provisions. In IWA-4150(c), it must include instructions for the preparation of the Repair/Replacement Plan used to
describe the specifics for a particular repair/replacement activity.
In IWA-4131.2(e), it must specify the size of Class 1 items to
which the alternative small requirements of IWA-4131 are to be
applied. In IWA-4411(i) (IWA-4411(h) in the 2001 Edition
through 2004 Edition and IWA-4410(c) prior to the 2001
Edition), it must include procedures for welding material control,
although this may be effectively met by making reference to the
Owner’s welding program that usually contains this information.
Although not specifically stated in IWA-4000, the following
“managerial and administrative controls” should be included in
the Repair/Replacement Program.
27.6
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(a) The Repair/Replacement Program should identify the
Section XI edition and addenda to be used for performing
repair/replacement activities.
(b) Although IWA-4150 does not require that Section XI Code
Cases be identified in the Repair/Replacement Program, the
Program should list all approved Section XI Code Cases
that have been or are anticipated to be used at the Owner’s
facility for repair/replacement activities. This may require
periodic revisions to the Repair/Replacement Program, but
the convenience of having a concise list of Section XI Cases
will prove beneficial and will also allow the responsible
organization to maintain control over the actual Section XI
Cases to be used at an Owner’s facility or by the
Repair/Replacement Organizations performing work for an
Owner. This control helps ensure that Cases have been
approved before their actual use. For a discussion on the
approval process required for use of Code Cases in the
United States, refer to the discussion on Code Cases in
Section 27.1.
(c) The Repair/Replacement Program should identify responsibilities for performance of the various aspects of
repair/replacement activities. The group with overall
responsibility for the Repair/Replacement Program should
be identified. Many Owners find it beneficial to have an
assigned individual responsible for coordinating the
repair/replacement activities. Organizations responsible for
review and approval of the Repair/Replacement Plans
should be identified.
(d) The Repair/Replacement Program should specify the
requirements for performing and documenting a repair/
replacement activity. For consistent application of the
IWA4000 requirements, some Owners find it worthwhile to
include the actual IWA-4000 requirements in the Repair/
Replacement Program. Doing so allows for further
clarification and explanation of the IWA-4000 requirements,
including use of Section XI interpretations, to assist the
Owner’s personnel in implementing the Program.
(e) The interface with the Owner’s work control processes
should be clearly stated.
(f) Controls to be used for making revisions to the Repair/
Replacement Plan and implementing work orders should be
included.
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REPAIR/REPLACEMENT PROGRAM
AND PLAN
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The Code change to add additional clarification for performance
of fabrication activities in IWA-4000, in locations other than IWA4143, was included in the 2005 Addenda. It also revised the definition of fabrication in IWA-9000 to clarify the differences between
fabrication in Section XI and fabrication in Construction Codes
where an ASME Certificate of Authorization is required. Prior to
the 1997 Addenda revision to IWA-4143(a), many Owners considered all of the work that they performed in replacing items to be
installation, to avoid the implication that they might be doing work
requiring an NPT Certificate of Authorization. With the 1997
change to IWA-4143(a), the distinction between fabrication and
installation took on a greater importance. The action included in
the 2005 Addenda was considered an editorial revision to add clarification to implement the 1997 Addenda changes to IWA-4143. A
review of all of Section XI and Section XI Code Cases was included, to ensure that the terms fabrication and installation were consistently used. Some minor inconsistencies in some Code Cases
were identified, which were determined to have no adverse effects.
It was concluded that changes to these Cases to clarify fabrication
and installation would be considered only if the Cases were
revised for some other reason.
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378 • Chapter 27
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This is another area where terminology and requirements have
changed from earlier editions and addenda. Initially, Section XI
required a Repair Program, which delineated essential requirements for completion of the complete repair cycle for a specific
repair. Interpretation XI-1-83-42 clarified that a Repair Program
was also to be prepared for the welded installation of an item to
be used for replacement. Later, in the Winter 1985 Addenda,
IWA7000 was revised to add a requirement for a Replacement
Program to describe and control a specific replacement. In the
1989 Addenda, IWA-4000 was revised to change what had previously been the Repair Program to what was renamed the Repair
Plan. Each repair was to have a Repair Plan that described the
specific aspects of a repair. Based on the way most Owners commonly used the term “program,” the Repair Program term was
redefined as the document or set of documents defining the managerial and administrative control for the completion of repairs. In
the 1991 Addenda, IWA-4000 and IWA-7000 were combined; the
Repair Program became the Repair/Replacement Program, whereas
the Repair Plan and the Replacement Program were combined to
become the Repair/Replacement Plan. These terms are still used
in the current Section XI.
27.6.1
Content of the Repair/Replacement Program
Section XI does not specifically identify the content of the
Repair/Replacement Program. It does describe the Program as the
document or set of documents defining the managerial and administrative control for the completion of the repair/replacement
activity. Some Owners have “program documents” that provide
upper-level control and define responsibilities over a group of
specific procedures and organizational groups within the company. Based on the brief description of what is to be in the Section XI
Repair/Replacement Program, an Owner may establish the
Repair/Replacement Program as one of these upper-level programs. However, the description specifically was made general so
that the Program would not need to be an upper-level program
document. An Owner may establish the Repair/Replacement
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approved in Regulatory Guide 1.147 Revision 13 [5], with no
conditions/limitations. Similarly, the NRC had approved without
limitation several editions and addenda of Section XI containing
the current IWA-4150(b) wording allowing the use of later editions and addenda of Section XI for repair/replacement activities.
Nevertheless, RIS 2004-16 concluded that licensees who wish to
use subsequent editions and addenda, or provisions of subsequent
editions and addenda, of ASME Section XI for activities, including repair/replacement activities (e.g., Code Case N-389-1), must
receive prior NRC review and approval as required by
10CRF50.55a(g)(4)(iv). The RIS stated that the purpose of the
NRC review and approval for the use of later editions and addenda of Section XI was to provide and monitor consistency in the
use of the appropriate editions and addenda in repair/replacement
activities. With the NRC conclusion contained in RIS 2004-16,
these provisions in Owner’s Repair/Replacement Programs
required revision to conform to the documented NRC position.
The NRC position documented in RIS 2004-16 can be
quite burdensome, especially when using a contract Repair/
Replacement Organization whose written Repair/Replacement
Program uses a later edition and addenda of Section XI than the
Owner’s Program. Owners need to make sure contracted
Repair/Replacement Organizations either use the same edition
and addenda used for the Owner’s Program or identify the later
editions and addenda, or portions thereof, so that the request can
be submitted to the NRC several months prior to the planned
repair/replacement activity.
Caution should be used regarding wording that occasionally
appears in older Section XI interpretations. Older Section XI
interpretations may include wording that indicates that a particular action may be performed “provided it is documented in the
Repair Program, which is subject to review by the enforcement
and regulatory authority having jurisdiction at the plant site.” For
example, Interpretation XI-1-86-51 uses this wording regarding
the use of alternative examinations:
TA
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(g) Terminology is a problem at most plants because the Code
defines and uses many terms quite distinctly in the Code
requirements—sometimes different from the way an Owner
might use the same terms in areas of the plant that are outside the Code jurisdiction. Therefore, it is useful to include
in the Repair/Replacement Program definitions of Code
terms important to the understanding and performance of
repair/replacement activities. Classic examples are
Certificates of Compliance (ANSI N45.2 versus ASME
Section III), item (general use meaning versus Codespecific definition), nonconformance disposition definitions
of rework and repair (ANSI N45.2 versus Section III and
Section XI), repair (general use meaning versus Codespecific activity), and part (general use meaning versus
Code-specific category of items).
(h) The Repair/Replacement Program should address requirements to be followed when contracting with a vendor to perform all or a portion of a repair/replacement activity. These
requirements should cover a vendor performing work onsite at the Owner’s facility as well as a vendor performing
work at its facility, including how to document the
repair/replacement activity and certify compliance with
Section XI. Several details that need to be addressed are
noted in Section 27.5.2.
(i) Requirements describing the involvement of an Authorized
Inspection Agency should be included.
(j) Requirements for completion and certification of the Form
NIS-2 (or Form NIS-2A if using Code Case N-532 or later
versions of the Case) should be included.
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As noted in the preceding list, the edition and addenda of
Section XI that is being used for repair/replacement activities,
including any specific provisions in later editions or addenda,
should be identified in the Repair/Replacement Program. The edition and addenda of Section XI to be used for repair/replacement
activities are required by IWA-4150(b) to correspond to the edition and addenda used for the Inservice Inspection Program for
the current inspection interval. Alternatively, IWA-4150(b) allows
the use of later editions and addenda, and even allows specific
provisions within later editions and addenda. When specific provisions in later editions and addenda are used, all related requirements shall be met so that a complete and consistent set of
requirements is used. Similar provisions are contained in Code
Case N-389-1 for Owners working to an earlier edition or addenda not containing the IWA-4150(b) alternative.
On October 19, 2004, the NRC issued Regulatory Issue
Summary 2004-16, Use of Later Editions and Addenda to ASME
Code Section XI for Repair/Replacement Activities. The stated
intent in the Regulatory Issue Summary (RIS) was to clarify the
requirements in 10CFR50.55a(g)(4)(iv) and the use of ASME
Section XI Code Case N-389-1, Alternative Rules for Repair,
Replacements and Modifications. RIS 2004-16 concluded that
licensees who wish to use provisions for repair/replacement activities contained in editions and addenda of ASME Section XI later
than the edition and addenda used for the ISI Program in accordance with 10CFR50.55a(g), must receive prior NRC review and
approval as required by 10CFR50.55a(g)(4)(iv).
The position documented by the NRC in RIS 2004-16 was different than the understanding of many Owners and different than
the provisions contained in many Owner’s Repair/ Replacement
Programs. Code Case N-389-1, had been added to Repair/
Replacement Programs based on the fact that the Case was
Question: Following installation of a replacement component
or piping assembly by welding in accordance with IWA-4600,
are the NDE examination requirements specified for installation welds in the original Construction Code required to be
met in addition to those specified in IWA-4500 and IWA7530?
Reply: Yes; however, when an examination requirement is
impossible or impractical to perform, an alternate examination may be used provided it is documented in the Repair
Program, which is subject to review by the enforcement and
regulatory authority having jurisdiction at the plant site.
This wording was inserted to make the user aware that an alternative may be possible if it were documented in the Repair
Program, for the Repair Program was subject to regulatory and
enforcement authority review. Because of the emphasis over the
last few years in the United States on compliance with the current
licensing basis, compliance with the Updated Final Safety
Analysis Report and, of course, because of the wording in
10CFR50.55a regarding alternatives to the requirements of the
Codes listed in 50.55a, it is not advisable to follow the approach
of documenting an alternative or exception to a Code requirement
in the Repair/Replacement Program without ensuring that the
alternative or exception has been approved in accordance with
appropriate Owner’s procedures and by the enforcement and
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Question: Is it permissible in the application of IWA-4120,
1980 Edition, to include later addenda and Code Cases as
well as later editions of the Code, when performing a repair
to the rules of Section III?
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Content of the Repair/Replacement Plan
Reply: Yes, Section XI allows the use of later editions of the
Code and the use of Code Cases when performing repairs, provided these requirements are specified in the Owner’s Repair
Program. You are cautioned that Code Cases are non-mandatory
and if they, or later editions and addenda of the Code, are
invoked the concurrence of the authorities having jurisdiction at
the plant site where the repair is performed would be required.
Owner’s Requirements also need to be in the Repair/
Replacement Plan. This inclusion is usually accomplished by a reference to the document(s) containing the Owner’s Requirements,
such as the Design Specification for plants constructed to Section III,
or to a specification, purchase order, or similar document for plants
constructed to older Codes. As discussed in Section 27.8, if an
Owner uses its design control process for updating the Owner’s
Requirements, changes from the original Owner’s Requirements
should have been evaluated and documented at the time they
occurred so that the current Owner’s Requirements can be used
without concern for what was contained in the original version.
However, if the changes were not evaluated and documented using
processes similar to the design control process, the original
Owner’s Requirements and the current Owner’s Requirements need
to be identified in the Repair/Replacement Plan so that subsequent
reconciliation can be performed.
Further clarification was provided by interpretation XI-1-01-03.
Question (1) has an applicability of the 1977 Edition with the
1978 Addenda through the 1995 Edition. Question (2) has an
applicability of the 1995 Edition with 1995 Addenda through the
2000 Addenda. Interpretation XI-1-01-03 is as follows:
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A Repair/Replacement Plan is required to be prepared for each
specific repair/replacement activity. The Repair/Replacement Plan
is to contain the essential requirements for completion of the
repair/replacement activity. IWA-4150(c) in the 1995 Addenda,
and in later editions and addenda, identifies specific information
that is required in the Repair/Replacement Plan. It is the responsibility of the Owner to review this information in detail and ensure
that it is included in the Repair/Replacement Plans; however, the
following paragraphs provide some discussion regarding the
nature and use of the Plans.
A Repair/Replacement Plan contains information that is important for planning the specific actions for performance of the
repair/replacement activity. Thus it is called a “Plan” for performing
the repair/replacement activity, and it also is a record maintained by
the Owner that describes the repair/replacement activity. Some
Owners have a specific document called a Repair/ Replacement
Plan, which they use to document the repair/replacement activity
and prepare the work orders used in the plant to perform the repair/
replacement activity. Other Owners, however, include this information in the work order and refer to the work order as the Repair/
Replacement Plan. Because the Code is not clear, either approach
should be acceptable, if all of the Code requirements are met.
Preparation of a Repair/Replacement Plan includes identification
of the Construction Code and Owner’s Requirements that were
used for construction and/or installation of the original item affected by the repair/replacement activity. Identification of these original
requirements is crucial in determining the requirements for performing the repair/replacement activity. As discussed later in
Sections 27.8 and 27.10, IWA-4000 refers to these Owner’s
Requirements and the original Construction Code for performance
of the repair/replacement activity. Therefore, determining these
original requirements is one of the first steps in planning the
repair/replacement activity.
It was common during plant construction to use a different
Construction Code, or a different edition and addenda of the
Construction Code, for constructing a component versus installing
a component. When the original component Construction Code is
different from the original installation Construction Code, both are
to be included in the Repair/Replacement Plan. When replacing an
item, the Construction Code for the replacement item is also to be
included in the Repair/Replacement Plan. Based on the specifics of
the repair/replacement activity to be performed, the Construction
Code(s) to be used for performing the repair/replacement activity
is then determined in accordance with IWA-4221 or IWA-4411
(IWA-4421 prior to the 2001 Edition) and listed in the
Repair/Replacement Plan. (Refer to Sections 27.8 and 27.10 for
further information about how to determine the applicable
Construction Code.) If the repair/replacement activity involves
activities such as obtaining replacement items or modifying a component, and the Construction Code to be used for the repair/replacement activity is different from the original component Construction
Code, a reconciliation is required by IWA-4220. By showing all of
these Construction Codes in the Repair/ Replacement Plan, the task
AS
27.6.2
of determining whether a reconciliation is required and what
Construction Codes are needed for ascertaining the details of the
repair/replacement activity is not difficult.
The term Construction Code used in this discussion includes
any Construction Code Cases, as noted by the definition of
Construction Code in IWA-9000. Both original Code Cases and
any revisions or additional Code Cases need to be listed in the
Repair/Replacement Plan along with the Construction Code.
Although it addresses only repairs, Interpretation XI-81-08, which
follows, clarifies the use of Code Cases and can be applied equally to replacements and to later Section XI editions and addenda.
Y
regulatory authorities, and is also consistent with the Owner’s
licensing basis. This wording has not been included in interpretations for several years because of these reasons. If users find this
condition in an interpretation, they should consider the possibility
of some alternative or exception and should also ensure that compliance with all Owner’s licensing commitments and the applicable enforcement and regulatory authority is maintained.
Question (1): Is it a requirement of IWA-4000 or IWA-7000
(as applicable) that design-only changes (i.e., no physical
work) be considered Repair, Replacement or Modification
activities?
Reply (1): No, use of the term “design change” in IWA-4000,
IWA-7000 and Appendix J only applies to activities which
involve physical work.
Question (2): Is it a requirement of IWA-4000 that designonly changes (i.e., no physical work) except rerating be considered a Repair/Replacement Activity?
Reply (2): No, use of the term “design change” in IWA-4000
and Appendix J only applies to activities which involve physical work or rerating.
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Question (1): Does Section XI specify when to begin a repair
or replacement activity?
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27.7
ADDITIONAL GENERAL
REQUIREMENTS
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Question (2): Is it a requirement of IWA-4000 and IWA-7000
that a repair or replacement plan be initiated for obtaining
items intended to be installed, at a later date, in Section XI
components or systems?
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Reply (1): Section XI provides rules for specific repair and
replacement activities but not when to begin a repair or
replacement activity.
IWA-4150(c)(7) requires the Repair/Replacement Plan to
include documentation in accordance with IWA-6000 (IWA-4180
and IWA-6000 prior to the 2003 Addenda). Documentation may
vary depending on the specific repair/replacement activity being
performed. Documentation needs to be addressed because the
Repair/Replacement Plan is to include the essential requirements
for completion of the repair/replacement activity and also because
of the documentation’s importance in demonstrating acceptability
of the repair/replacement activity. It is possible to prepare the
Repair/Replacement Program so that some documentation is
addressed by the Program and therefore does not need to be
included in each Repair/Replacement Plan, such as the preparation
of Form NIS-2. Additionally, if the repair/replacement activity
affects design documents such as the Design Specification, Design
Report, and Overpressure Protection Report, the documentation of
the effect on the design documents is normally addressed in a
design change package that can be included, by reference, in the
Repair/Replacement Plan. Material certification may be directly
included in the Repair/Replacement Plan, or it may be included by
reference to the documents or locations where the material
certifications are contained. The key point to consider is that the
Plan is required to either contain the documentation or to be a
“road map” to the location of documentation applicable to the
specific repair/replacement activity being performed.
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Design provisions were added to IWA-4300 in the 1995
Addenda and 1996 Addenda. With IWA-4000 requirements now
specifically addressing design, a task that typically precedes the
in-plant physical work by a considerable amount of time, the
question has arisen regarding when the repair/replacement activity
begins and when a Repair/Replacement Plan is required to be initiated. Interpretation XI-1-95-16, discussed in the forthcoming
paragraph, had previously noted that Section XI did not provide
rules on when to begin a repair/replacement activity. Therefore, to
clarify this question, IWA-4150(c) was revised in the 1997
Addenda to note that Repair/Replacement Plans are not required
for the design phase of a repair/replacement activity. The 1997
Addenda also stated that a Repair/Replacement Plan was not
needed for repair/replacement activities that require design only,
such as rerating and use-as-is nonconformance dispositions.
A similar question is whether a Repair/Replacement Plan is
required before obtaining replacement items. Interpretation
XI-195-16, which follows, clarified this situation as well.
Reply (2): No.
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IWA-4150(c)(5) notes that the Repair/Replacement Plan is to
contain the expected life of the item after completion of the
repair/replacement activity when the expected life is less than the
remainder of the previous intended life (design life when specified in the Design Specification) of the item. This wording refers
to temporary repair/replacement activities that meet Section XI
and the Construction Code but aren’t intended to last for the
remaining design life of the item. Use of the term “temporary
repair” was not acceptable to the ASME BP&V Main Committee,
so the wording was revised to refer to the intended life when less
than the remainder of the design life. This provision was added in
the 1988 Addenda to acknowledge that repairs may be suitable for
an acceptable time period but may not be justified to last the for
entire projected life of the item. For example, one may make a
weld repair to build up an eroded area knowing that the buildup
will suffer from the same degradation mechanism but the weld
repair will allow time for an erosion-resistant replacement to be
made and installed at a later time. This concept was later expanded to include replacement, such as installing an identical replacement for a time period less than that of the remaining design life.
The current IWA-4150(c)(5) wording was part of a change in
the 2006 Addenda to address required actions when the expected
life was less than the intended life of the item. The required
actions were included in IWA-4160 along with terminology
changes included in IWA-4150(c)(5). Because the term “design
life” is not used in any Construction Codes other than Section III,
Division 2, for concrete containments, intended life was used
instead of design life, with clarification that this is the design life
when design life is specified in the Design Specification. The
related change to IWA-4160 is discussed in Section 27.7.1.
Although many general requirements have been presented up to
this point, three additional subjects remain in the IWA-4100 subarticle “General Requirements”: verification of acceptability,
inspection by an Authorized Inspection Agency, and documentation, all of which are discussed in the forthcoming paragraphs.
27.7.1
Verification of Acceptability
Users of the earlier editions and addenda recognize IWA4160(a) as a combination of provisions from IWA-4000 and IWA7000. IWA-4130, “Repair Program,” presented a requirement to
evaluate the suitability of a repair before authorizing the repair.
IWA-7220, “Verification of Acceptability,” included requirements
to conduct an evaluation of the suitability of a replacement item
before authorizing installation of the item. It also included provisions to be followed if the replacement was required because of a
failure. These requirements were combined as a new IWA-4150 in
the 1991 Addenda, when IWA-4000 and IWA-7000 were combined. IWA-4150 was renumbered as IWA-4160 in the IWA-4000
rewrite in the 1995 Addenda.
IWA-4160(b) was added in the 2006 Addenda and is discussed
later in this Section.
The provisions for evaluating and documenting suitability of a
replacement required unnecessary redundancy when the purpose
of the replacement was for a modification or like-for-like replacement not associated with service-induced failure. This redundancy
was eliminated in a revision published in the 1994 Addenda (these
provisions were also included in Code Case N-556) that required
that the suitability be evaluated only “if an item does not satisfy
the requirements of this Division,” that is, Section XI, Division 1.
By eliminating the term failure and replacing it with the phrase “if
an item does not satisfy the requirements of this Division,” this
change also addressed in the Code the question of what was a failure, as previously resolved by Interpretation X1-1-92-15, which
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follows. In this interpretation, Subcommittee XI concluded that
Section XI did not define what constituted a failure, nor did it
intend to define failure.
Question: Section XI, IWA-7220 states in part, “If a replacement is required because of failure of a part or component,
the evaluation shall consider cause(s) of failure of the existing part or component to ensure that the selected replacement
is suitable.” Is “failure” as used in IWA-7220 defined as a
part or component being incapable of accomplishing its system safety function?
IWA-4160(b) applies for all repair/replacement activities when
the expected life of the item is less than the intended life of the
item. IWA-4160(b) requires the Owner to initiate actions that will
result in a plan for additional examinations and evaluations to verify the acceptability of the item for continued service or to schedule subsequent repair/replacement activities prior to the end of the
expected life of the item.
27.7.2
Authorized Inspection Agency Involvement
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The services of an Authorized Inspection Agency are required
whenever repair/replacement activities are performed, as stated in
IWA-4170. IWA-2120 requires the Authorized Inspection Agency
to be accredited by ASME in accordance with ASME QAI-1. The
Authorized Inspection Agency, including the Authorized Nuclear
Inservice Inspection Supervisor, Authorized Nuclear Inservice
Inspector (ANII), and Authorized Nuclear Inspector (ANI), must
meet the requirements of ASME QAI-1. ASME QAI-1 specifies
duties of the ANI and ANII in addition to those stated in IWA2100. QAI-1 requires that an ANII also have the ANI endorsement. Because the standard practice is for an ANII to perform
these activities, this chapter’s discussion refers to the ANII rather
than distinguishing between the responsibilities of the ANI and
ANII. IWA-2100( j) and (k) require the ANII to verify that
repair/replacement activities are performed in accordance with the
requirements of the Owner’s Repair/Replacement Program and
also require the ANII to review the Repair/Replacement Program
and its implementation.
IWA-4170 requires the Owner or the Repair/Replacement
Organization (if the Owner is not the Repair/Replacement
Organization) to notify the ANII before starting a repair/replacement activity and to keep the ANII informed of progress so that
the necessary inspections may be performed. It should be noted
that IWA-4000 requires the involvement of an ANII even if the
original Construction Code did not use the services of an
Authorized Inspection Agency. Although Section XI does not
require the ANII to sign off on the Repair/Replacement Plan and
implementing work order, it is a common practice by most
Owners and Repair/Replacement Organizations and also provides
a practical way of demonstrating compliance with the requirements of IWA-2100( j). By obtaining the ANII’s review and concurrence of the planned work, the ANII identifies the required or
requested ANII inspections and has the opportunity to express
concerns or ask questions before the performance of the repair/
replacement activity. After completion of the repair/replacement
activity, the ANII is required to sign Form NIS-2, which documents that the repair/replacement activity was performed in
accordance with Section XI requirements. Therefore, the
Repair/Replacement Organization is advised to resolve any ANII
concerns before performing the repair/replacement activity rather
than discovering after the work is completed that some requirements of Section XI were not met.
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The 1994 Addenda (and Code Case N-556) also removed some
of the concerns regarding the timing of the evaluation of suitability
by stating that the Owner was required to evaluate the suitability
before returning the item to service. Previous wording stated that
the evaluation was required to be conducted before installation of
an item. This additional time allows an Owner to perform installation activities concurrent with performance of the evaluation
when the required allowed out-of-service action times of the
plant’s Technical Specifications limit the available time for returning the system to service. A question about when the evaluation is
required to be documented resulted in Interpretation XI-1-95-02,
which follows.
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Reply: Section XI does not define the term “failure.” What
constitutes a failure is the responsibility of the Owner based
on case by case details and the specifics of the Owner’s
Program.
Question: Is it a requirement of IWA-7220 that the evaluation
be documented prior to authorizing installation of the
replacement?
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Reply: No, the requirement does not specify the time for documentation.
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Prior to the 2000 Addenda, IWA-4160, including the previous
IWA-7220 paragraph, contained a provision that if the requirements for the original item are determined to be deficient, appropriate corrective provisions shall be included in the Owner’s
Requirements and Design Specification. It further required that
the corrective provisions shall be consistent with the edition and
addenda of the Construction Code or Section III in effect at that
time. This requirement to use the latest Construction Code or
Section III conflicted with the philosophy of IWA-4000, which
has consistently required the Owner to make repairs to the original Construction Code of the item or to later Codes that have been
reconciled for use. Consequently, a Code change was published in
the 2000 Addenda to eliminate the requirement for the corrective
provisions to be consistent with the edition and addenda of the
Construction Code or Section III in effect at the time of the
replacement.
Prior to the 2006 Addenda, IWA-4150(c)(5) required the
Owner to determine the intended life of a replacement item when
that life was less than the remainder of the item’s previous design
life; however, IWA-4150(c)(5) did not have any requirements for
the Owner to do anything with that information. The 2006
Addenda revised terminology in IWA-4150(c)(5) (refer to Section
27.6.2 for discussion of those changes) and added a new paragraph (b) to IWA-4160 to address the required actions when the
expected life was less than the intended life. While IWA-4160(a)
applies only to items that do not satisfy Section XI requirements,
27.7.3
Documentation
IWA-4000 and IWA-6000 identify reports and records that are
to be prepared and maintained by the Repair/Replacement
Organization. Additionally, by the Section XI reference to the
Owner’s Requirements and Construction Code for performing
repair/replacement activities, the Owner’s Requirements and
Construction Code requirements identify additional documentation that is required to be prepared and maintained for the
repair/replacement activity. Requirements for the maintenance of
the required documentation are identified in IWA-6000. These
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27.7.3.1 Reports and Records for Repair/Replacement
Activities The following three paragraphs discuss the requirements applicable prior to the 2003 Addenda.
Out of all of the documentation generated for repair/replacement activities, IWA-4180(b) selectively addressed only certain
documents. These documents can be separated into two categories.
The first category comprised significant documents required by the
applicable Construction Code; included in this category were
Design Specifications, Design Reports, Overpressure Protection
Reports, Manufacturer’s Data Reports, and Material Certifications.
The second category comprised documents specifically required
to be prepared by IWA-4000 requirements; included in this category were evaluations required by IWA-4160 and IWA-4311, the
Repair/Replacement Program, Repair/Replacement Plans, and reconciliation documentation. Form NIS-2 required by IWA-4180(d)
also fits into this category.
The list in IWA-4180(b) originated in the Summer 1976
Addenda when requirements for replacements were added to
Section XI. The list had the same distinctive Section III orientation, as evident in IWA-4180(b) up through the 2002 Addenda. As
with many of the Section XI requirements that originated in the
1970s, there was considerable emphasis on Section III requirements. This emphasis was partially attributed to the fact that
Section XI requirements were initially prepared by the Subgroup
on Inservice Inspection under Subcommittee III with the understanding that Section XI would be applied only to plants constructed to Section III requirements. This original understanding
was not maintained as the benefits of Section XI to all plants
became obvious and also as regulatory authorities made Section
XI mandatory for operating plants regardless of the original
Construction Code. However, the list in IWA-4180(b) was not
revised to use terms that would apply generically to all plants.
Clarification regarding the Design Reports identified in IWA4180(b)(2) is worth mentioning. The original list in the Summer
1976 Addenda included both the Certified Stress Report and the
Design Report. Section III, in the original 1963 Edition, required
a Certified Stress Report for Class A and B vessels and maintained the use of a Certified Stress Report up to the Summer 1978
Addenda, when the term was changed to “Design Report” and its
meaning revised to address all Classes. (Class 1 components and
some Class 2 vessels still required the Design Report to be
certified by a Registered Professional Engineer.) B31.7 also
required a Certified Stress Report for Class 1 piping. The Draft
Pump and Valve Code used the term Design Report for Class 1
pumps and valves. Section III used the term Design Report at
least as early as the 1971 Edition for some Class 2 vessels. As
noted previously, Section III started using the term Design Report
for all Classes in the Summer 1978 Addenda. With this history of
different terms all denoting the calculations performed to show
compliance of components with the applicable Design
Specification, Subcommittee XI, during a revision in the 1996
Addenda, simplified the list in IWA-4180(b) by combining the
terms of Certified Design Report and Design Report into one
generic term: Design Report. This simplification was not intended
to eliminate some of the documents.
In the 2003 Addenda, changes were made in an attempt to consolidate documentation requirements. Prior to this change, IWA4180 contained requirements for documentation update and maintenance while IWA-6000 contained requirements for preparation,
submittal, and retention of records and reports. Similarities existed
between the content of IWA-4180 and IWA-6000. The 2003
Addenda change deleted IWA-4180, distributed its contents to other
appropriate locations in Section XI and changed references
throughout Section XI where IWA-4180 was previously referenced.
The IWA-4180(b) requirement to maintain Design Specifications,
Design Reports, and Overpressure Protection Reports was moved to
a new IWA-4311(e) paragraph. The IWA-4180(b) requirement to
maintain manufacturer’s Code Data Reports and material
certifications was deleted because these documents were generated
by requirements contained in the Construction Code referenced by
Section XI and were considered to be the same as the construction
records addressed in the existing IWA-6330. IWA-6330
specifically refers to NCA-4134.17, where Code Data Reports
and Certified Material Test Reports are classified as lifetime
records that must be retained. Users should understand that the
intent was that IWA-6330 addresses both the repair/replacement
activity records generated by the Section XI reference to the
Construction Code and the earlier construction records generated
by the Construction Code used during the original plant construction prior to initial operation. Unfortunately, this intent is not
clear from the IWA-6330 title, “Construction Records”, which
implies those records generated during the original plant construction prior to initial operation. However, by generically
addressing not only Section III constructed plants but also the
older plants not built to Section III, the changes to IWA-6330 did
clarify the longstanding intent that repair/replacement activity
records required by the Construction Code and Owner’s
Requirements shall also be retained. The requirement in IWA4180(b) to maintain evaluations required by IWA-4160 or IWA4311, Repair/Replacement Program and Plans, and reconciliation
documentation was moved to a newly created IWA-6350, titled
“Repair/Replacement Activity Records.”
IWA-4180(d) prior to the 2003 Addenda and IWA-6350 in the
2003 Addenda and later editions and addenda require that Form
NIS-2 be completed for all repair/replacement activities. Form NIS2 is titled “Owner’s Report for Repair/Replacement Activity,”
although it is not strictly an Owner’s Report; it is a report by the
Owner if the Owner is the Repair/Replacement Organization or the
Owner’s designee (i.e., the Repair/Replacement Organization) if
the Owner is not the Repair/Replacement Organization. A sample
Form NIS-2 and instructions for completing it are contained in
Appendix II of Section XI. Form NIS-2 is the Section XI equivalent
to a Construction Code Data Report. A completed Form NIS-2 is
both a report of the repair/replacement activity performed as well as
a certification by the Owner or Repair/Replacement Organization
that the report, and the repair/replacement activity described therein, conform to the requirements of Section XI. Form NIS-2 is also
signed by the ANII, which signifies that the ANII has performed
the required Section XI inspections and that to the best of his/her
knowledge, the Repair/Replacement Organization has performed
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requirements, along with regulatory requirements and the
Repair/Replacement Organization’s QA Program, identify the
documentation required to be prepared and maintained for
repair/replacement activities.
Prior to the 2003 Addenda, IWA-4180 contained much of the
requirements for documentation for repair/replacement activities.
In an attempt to consolidate documentation requirements, a
change made in the 2003 Addenda deleted IWA-4180 and distributed its contents to new paragraphs IWA-4311(e) and IWA-6350
and to a revision to IWA-6330. The following Sections 27.7.3.1
and 27.7.3.2 will provide discussion of the requirements applicable prior to the 2003 Addenda as well as those applicable with the
2003 Addenda and later editions and addenda.
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Revisions to existing reports, records, and specifications may
be shown as an amendment, or as a supplement, and attached
to the original record or report to provide an up-to-date record
of the replacement.
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This provision required that reports, records, and specifications—
that is, those identified in the IWA-7520 list, were to be maintained
to provide an up-to-date record of the replacement. Rather than
revise these documents, which was the typical Construction Code
requirement, permissive methods to keep these documents up
to date included amendments or supplements that could be
attached to the original documents. However, discussion at
meetings of the Section XI Subgroup on Repairs, Replacements,
and Modifications in the early 1990s revealed that some Owners,
and the organizations performing design for the Owners, were not
following this requirement. The Subgroup noted that the requirement needed to be clarified; consequently, it opened an action item
to revise the Code. The explanation for that action item was as follows: “IWA-4910 [this was IWA-7520 before the 1991 addenda,
when it became IWA-4910] requires the Owner to maintain
Design Reports, but it isn’t clear what actions are required, and
when they are required. For design or configuration changes, this
action revises [the Code] to clarify that the Owner is required to
document an evaluation or reanalysis. This is applicable for all
Construction Codes, not just Section III.” This action item was
approved and published as a new paragraph IWA-4311 in the 1995
Addenda. In another action item, the Committee revised IWA4311 to clarify that Design Specifications need to be kept current
when design or configuration changes to plant items are made.
This change also revised the method in IWA-4180(c) for keeping
the documents current. The changes to IWA-4311 are discussed
further in Section 27.9, but the important point to note here is that
these changes confirmed the original intent to keep an up-to-date
status of these documents as stated in the original words in IWA7520 in the Summer 1976 Addenda.
The change to IWA-4180(c) in the 1996 Addenda revised the
method for keeping the documents in IWA-4180(b) up to date.
The requirement that existed since the Summer 1976 Addenda
noted that revisions to the documents could be made as amendments or supplements intended to be attached to the original documents. However, the change occurring in the 1996 Addenda was
intended to allow more flexibility for Owners possessing document control systems containing linking processes that provided
traceability to and from both the original document and the documents that update the original document. Stated another way, the
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27.7.3.2 Up-To-Date Status of Certain Construction Code
Documents IWA-7520 in the Summer 1976 Addenda originated a
list of documents to be maintained. IWA-7520 contained the following provision:
document control system information for the original document
identifies those documents that update the original document to
ensure an up-to-date status. Conversely, the document control system information for the documents that update the original document identifies the original document, as well as identifies the
other updates, to ensure an up-to-date status. Although the subject
is not addressed in the Code requirements, Owners are cautioned
that if the number of updates becomes large, the ability of Owner
personnel to use the aforementioned system to ensure an understanding of the current design and configuration of the item could
be substantially affected. Of course, actually revising the document or using the earlier method of attaching an amendment or
supplement to the original document would also meet IWA-4180(c)
provisions and could continue to be used. For that reason, Owners
might consider these methods to be more user-friendly than the
IWA-4180(c) provisions for updates.
As noted in the previous Section 27.7.3.1, changes were made
in the 2003 Addenda in an attempt to consolidate documentation
requirements. Prior to this change, IWA-4180 contained requirements for documentation update and maintenance while IWA-6000
contained requirements for preparation, submittal, and retention
of records and reports. Similarities existed between the content of
IWA-4180 and IWA-6000. The 2003 Addenda change deleted
IWA-4180, distributed its contents to other appropriate locations
in Section XI and changed references throughout Section XI
where IWA-4180 was previously referenced. Because IWA-4311
already contained requirements to keep design and configuration
documents up to date, the requirements in IWA-4180(c) to perform revisions and updates to existing reports, records, and
specifications, to have these revisions and updates traceable to the
original records or reports, and to have them reviewed and
certified in accordance with Owner’s Requirements and the
Construction Code, were moved to a newly created IWA-4311(e).
Therefore, the 2003 Addenda revision did not really change the
requirements to keep documents up-to-date, but simply
rearranged the location of the requirements.
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the repair/replacement activity in accordance with the requirements
of Section XI. Code Case N-532 and later versions of the Case contain an alternative form—Form NIS-2A—that may be used instead
of Form NIS-2 if the Code Case was adopted and included in the
Owner’s Repair/Replacement Program. Code Case N-532-4 is
approved by the NRC for use without conditions in Regulatory
Guide 1.147, Rev. 15 [17]. Form NIS-2A is a shortened report that
refers to the Owner’s Repair/Replacement Plan for details of the
repair/replacement activity rather than including the details in the
report. However, the same certifications and signatures required on
Form NIS-2 are also required on Form NIS-2A.
27.8
REQUIREMENTS FOR ITEMS USED
IN A REPAIR/REPLACEMENT
ACTIVITY
IWA-4210, “General Requirements,” is noted as being “in
course of preparation.” The Section XI Subgroup on Repairs,
Replacements, and Modifications had planned to prepare requirements for procurement of replacement items and include those
requirements in IWA-4210 when completed and approved by the
B&PV Committee. Preparation of such requirements is stalled
and will not be added in the near future.
IWA-4220 provides requirements for items that are added,
modified, or used to replace an existing item. The requirements of
IWA-4200 originate from IWA-7210 before the 1991 Addenda,
which was used to determine the applicable requirements for
replacement items. These original requirements have been substantially revised to improve clarity and usability. Additionally,
significant new provisions have been added, such as provisions
for the addition of new systems, and also improved and expanded
provisions for the reconciliation of Construction Codes and
Owner’s Requirements. These changes are discussed in the forthcoming paragraphs.
In the 2001 Edition as part of significant changes to IWA-4400,
requirements for helical-coil threaded inserts were moved from
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As noted previously, these requirements originated in IWA7210, which essentially stated that items to be used for replacement shall meet the existing design requirements and the
Construction Code to which the original item was constructed.
Although the essence of this requirement has not changed, numerous other changes have been made. For instance, the location of
the requirements has changed, new terminology has been introduced, and clarification has been added for determining the
Construction Code when installing a new item in an existing system (i.e., no existing item is being replaced). Provisions were
added to allow a replacement item to meet earlier as well as later
editions and addenda of the Construction Code or even different
Construction Codes. One other substantial change was made in
the 1997 Addenda, when the scope of IWA-4000 was revised to
allow the addition of complete new systems. Provisions were
included in IWA-4221 to determine the Construction Code to use
when a new system is added. These changes and the current
requirements are discussed in the forthcoming paragraphs. These
provisions have also been included in Code Case N-554-3 for use
by Owners working to earlier editions and addenda of Section XI.
This Code Case includes the provisions included in the 2001
Edition through the 2003 Addenda.
When the requirements for repair and replacement were combined in the 1991 Addenda, IWA-7210 requirements were relocated to IWA-4170. As part of the IWA-4000 rewrite in the 1995
Addenda, the requirements were relocated to the current IWA4221. These different paragraph numbers are noted here partly
because Owners find them helpful when they upgrade to later
Section XI editions and addenda, and partly because these paragraphs are referenced in the interpretations noted in the forthcoming paragraphs.
New terminology was included in a revision to IWA-4000 in
the 1993 Addenda. The new term Owner’s Requirements was
introduced and the definition of Construction Code was revised.
This revision and the new terms are discussed in section 27.5.1.
IWA-4221 currently has three subparagraphs: IWA-4221(a),
which addresses Owner’s Requirements; IWA-4221(b), which
addresses the applicable Construction Code; and IWA-4221 (c),
which provides alternatives for the Construction Code identified in
IWA-4221(b). Each of these subparagraphs is discussed as follows.
IWA-4221 (a) requires that an item to be added or replaced
shall meet the applicable Owner’s Requirements. Alternatively,
revised Owner’s Requirements may be used provided they are
reconciled in accordance with IWA-4222. Documentation of the
reconciliation is required. This requirement to reconcile and to
document that reconciliation of revised Owner’s Requirements
should easily be met by Owners who work to Construction Codes
that require Design Specifications. IWA-4311(e) (IWA-4180(c)
prior to the 2003 Addenda) requires documentation, such as
Design Specifications (i.e., Owner’s Requirements), to be kept up
to date to provide a current status of the item. To accomplish this
task, an Owner needs to evaluate the revision of a Design
Specification in accordance with the Owner’s QA Program, which
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Construction Codes
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27.8.1
includes a design change process. This process ensures that the
change is acceptable for the items covered by the Design
Specification. The Owner’s design change processes should be
adequate to meet a requirement to reconcile changes in the
Owner’s Requirements, especially if the applicable Section XI
reconciliation requirements are considered during the design
change process. Additionally, documentation prepared by the
Owner’s design change process should be adequate as reconciliation documentation; in such cases, Owners do not need to prepare
additional documentation. The revision of the Design
Specification becomes the “current design” for the items covered
by the Design Specification (i.e., the revised Owner’s
Requirements). When a repair/replacement activity is to be performed on an item, there is no need to reconcile the current design
against the original Design Specification because this task already
has been accomplished. However, reconciliation of changes to the
original Owner’s Requirements is required to be performed and
documented by Owners of older plants for which Design
Specifications were not required and when the sources of the
Owner’s Requirements are not kept up to date.
IWA-4221(a) wording was revised slightly in the 2003
Addenda to acknowledge that most Owners revise their Owner’s
Requirements and, therefore, need only reconcile changes by
reviewing the existing Owner’s Requirements rather than the original requirements.
It should be noted that some technical changes to Owner’s
Requirements are changes occurring only once and often are not
incorporated into Design Specifications or revised Owner’s
Requirements. Examples include nonconformance repair or useas-is dispositions. It is adequate to reconcile these changes against
the current design (i.e., the current Owner’s Requirements); however, if an Owner does not maintain current Owner’s
Requirements, reconciliation of the changes should be against the
original Owner’s Requirements. Again, the design change process
used in justifying and approving the repair or use-as-is disposition
should be adequate for documenting an acceptable reconciliation,
especially if the applicable Section XI reconciliation requirements
are considered during the design change process.
A Code change published in the 2000 Addenda clarified the
intent of the Code regarding the Report of Reconciliation required
by IWA-4180, IWA-4220, and IWA-4421. The explanation for
that change is as follows:
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IWA-4451 to a new IWA-4230. This change was made because the
requirements in IWA-4451 primarily addressed how to obtain these
threaded inserts, which better aligned with IWA-4200 rather than
IWA-4400. Accordingly, the second edition of the Companion
Guide moved the discussion of helical-coil threaded inserts from
the first edition Section 27.10.7 to a new Section 27.8.4.
The current wording [1999 Addenda] could appear to require
the creation of a unique document every time a reconciliation
is performed. Reconciliation documentation may include a
specific evaluation for a repair/replacement activity or it may
be a part of other documentation prepared by, or for, the
Owner, as in an evaluation accompanying a modification
package, as long as the evaluations required by IWA-4223
through IWA-4226 are conducted and documented.
The change eliminated the Report of Reconciliation and instead
referred to reconciliation documentation. An interpretation was also
issued to clarify the Code for users working to an edition and addenda published before this Code change. Interpretation XI-1-98-66R is
applicable to the 1995 Edition with the 1995 Addenda through the
1998 Edition with 2000 Addenda and is as follows:
Question: Is it a requirement of IWA-4180, IWA-4220, and
IWA-4421 (IWA-4410 in the 1995 and 1996 Addenda) that the
Report of Reconciliation be a separate and unique document?
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Reply: No. Any documents that satisfy the evaluation requirements contained in IWA-4220 may be used to record reconciliation activities.
Article shall be documented. All or portions of later different
Construction Codes may be used as listed below:
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Four comments regarding these provisions in IWA-4221(c) are
necessary. First, an alternative Construction Code can be a different
edition and addenda of the same Construction Code - either an earlier or later edition or addenda. Second, Section III may be used if
the original Construction Code was not Section III (this provision is
the same as earlier Section XI requirements). Third, other different
Construction Codes are allowed, in which each type of component
has an acceptable list of Codes and an acceptable progression direction. It is not acceptable to go backward in the progression; for
example, it is not acceptable to go backward from B31.7 to B31.1.
However, it is acceptable to move forward to a different Code or to
skip forward directly to Section III, but it is not acceptable to go
from Section III to any other Code. Fourth, portions of the requirements of different editions and addenda of the Construction Code,
or of Section III, or of different Construction Codes, may be used.
This use permits a portion of a selected alternative Construction
Code to be used if all related requirements are met and a complete,
consistent set of Code requirements is used—that is, a portion of
the selected alternative Construction Code, when it is combined
with the remaining portion of the original Construction Code, provides a complete and consistent set of Code requirements.
However, caution must be deployed when one uses portions of a
Code. Inexperienced users might not recognize the related requirements in the alternative Construction Code that must be used with
the portion of the alternative Construction Code selected for use.
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IWA-4221(b) addresses the applicable Construction Code for
an item used in a repair/replacement activity. It was added in the
1997 Addenda as part of a change to revise IWA-4000 to include
the addition of complete new systems. The requirement in existence before the 1997 Addenda stated that the item was to meet
the requirements of the Construction Code to which the original
item was constructed. When the change to add complete new systems was prepared, the requirement to use the original
Construction Code was not considered meaningful when a new
item was added (i.e., when there was no original item to be
replaced). Therefore, IWA-4221(b) was prepared to identify three
conditions and provide requirements for the applicable Construction
Code for each of these conditions. First, when an existing item is
replaced, the new item needs to meet the Construction Code for the
original item (as always required by the Code). Second, when a new
item is added, the Owner needs to specify a Construction Code that
does not predate the earliest Construction Code used for the construction of any originally installed item in the system. Third, when
a new system is added, the Owner needs to specify a Construction
Code that does not predate the earliest Construction Code used
for other systems that perform a similar function. The use of
Construction Codes of similar editions and addenda as those of
other systems that perform a similar function is consistent with
Section XI philosophy, which concludes that existing Codes can
continue to be used throughout the life of the plant. It also eliminates
the Owner’s expense of purchasing and stocking additional items for
use as replacements in systems with newer Construction Codes, and
also allows an Owner to continue the use of Construction Codes
with which the Owner’s personnel are familiar and that the Owner’s
procedures already address.
Before looking at the current requirements for IWA-4221(c), it
is helpful to review the background of those requirements. The
requirements for an alternative to the original Construction Code
were first included in IWA-7210(c) of the Summer 1976
Addenda and remained essentially unchanged through the 1986
Edition. IWA-7210(c) allowed replacements to “meet all or portions of the requirements of later editions of the Construction
Code” if certain requirements were met. Those requirements permitted use of the later editions and addenda and are known as the
replacement reconciliation requirements. (Reconciliation is discussed in Section 27.8.3.) In the 1986 Addenda, IWA-7210(c)
was revised to allow an item to alternatively “meet all or portions
of the requirements of later editions of the Construction Code or
Section III when the Construction Code was not Section III. . . .”
The content of the current IWA-4221(c) was added in the 1995
Addenda as part of an effort by the Working Group on Design
Reconciliation to rewrite the IWA-4000 reconciliation requirements. Included in the rewrite was an expansion of the
Construction Codes that could be used as alternatives to meeting
the original Construction Code of the item to be replaced. IWA4221(c) states the following:
(1) Piping, piping subassemblies, and their supports:
B31.1 to B31.7 to Section III.
(2) Pumps, valves, and their supports: from B31.1 to
Draft Code for Pumps and Valves for Nuclear Power
to Section III.
(3) Vessels and their supports: Section VIII to Section III.
(4) Atmospheric and 0-15 psig (0-100 kPa) storage tanks
and their supports: Section VIII, API 620, or API 650
to Section III.
As an alternative to [IWA-4221(b)], the item may meet all or
portions of the requirements of different Editions and Addenda
of the Construction Code, or Section III when the Construction
Code was not Section III, provided the requirements of IWA4222 through IWA-4226, as applicable, are met. Construction
Code Cases may be used. Reconciliations required by this
27.8.2
Interpretations on Use of Construction Code
Requirements
The Section XI reference to the Construction Code for obtaining replacement items has resulted in several Section XI interpretations. These interpretations, some of which appear here, provide
the user with clarification.
The first three interpretations that follow are self-explanatory
and address how to implement Construction Code requirements
when one works within the jurisdiction of Section XI.
Interpretation XI-1-89-68:
Question: In accordance with Section XI, IWA-7210, may a
component that was originally constructed to Section III be
replaced by a component that has been designed and manufactured by an organization that does not possess an appropriate Certificate of Authorization?
Reply: No.
Interpretation XI-1 -79-01:
Question (1): Is it the intent of Section XI, Division 1 that an
organization without a manufacturing facility is required to
have an ASME Certificate of Authorization to procure
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components, replacement parts, and material for existing
nuclear plants?
that do not hold a QSC. Consequently, Owners of plants built to
Section III are at an economic disadvantage for procuring materials when compared to Owners of older plants, which do not need
to follow the requirements of NA-3700/NCA-3800. However, two
Section XI Code Cases provide alternatives to some of the Section
III NA-3700/NCA-3800 requirements. Code Case N-517-1 allows
Owners to qualify Material Organizations (the equivalent terms in
earlier Section III editions were Material Manufacturers and
Material Suppliers), to use unqualified source material (the equivalent description in earlier Section III editions was “to upgrade stock
material”), and to use Section III NX-2610 provisions for small
products. Code Case N-528-1, on the other hand, allows Owners to
purchase, exchange, or transfer materials from other Owners without the need to audit and qualify the Owner in accordance with the
requirements of NA-3700/NCA-3800. Additional alternatives are
also being considered by Subcommittee XI. Code Case N-517-1
was incorporated into the Code in the 2007 Edition as a new paragraph IWA-4142.1 (refer to Section 27.5.2). Code Case N-528-1
was incorporated into the Code in the 2006 Addenda as a new paragraph IWA-4134 (refer to Section 27.4.4).
The following three interpretations show the implementation of
Section III NA-3700/NCA-3800 for Owners not using either of the
two Code Cases or a later Code Edition and Addenda that includes
incorporation of the Cases as noted in the previous paragraph.
Interpretation XI-1-89-24:
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Reply (1): It is not necessary under the rules of Section XI,
Division 1, IWA-7000, for an organization to be in possession
of an ASME Certificate of Authorization to procure replacements. If, however, it is required by the edition of the
Construction Code specified by the Owner, the replacement
manufacturer, material supplier, or material manufacturer
must have the appropriate ASME Certificate of Authorization
or Quality System Certificate (Materials). In any case, documentation of the replacement must be provided in accordance
with the Owner’s Quality Assurance Program (in accordance
with regulatory authority requirements).
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Question: Under the provisions of Section XI, Division 1,
IWA-7330, an Owner who does not possess an NA Symbol
Stamp is allowed to install an item to be used for replacement. Under the provisions of Section XI, Division 1, IWA7210, may an Owner who does not possess an NA Symbol
Stamp be permitted to qualify (in accordance with Section III,
NCA-3800) material manufacturers and suppliers that furnish the material being installed?
TA
Reply (2): Section XI, Division 1, IWA-7210 states that the
requirements of the Construction Code shall be applied to
replacements; reactor vessel studs, washers, and nuts that
are manufactured to an SA or SB Specification, or any other
material specification permitted by Section III are defined in
NCA-1220 as materials. The Owner is responsible for specifying the requirements for replacement components, parts,
and materials, and the applicable edition of the
Construction Code. The requirements of the specified edition of the Construction Code will determine whether or not
the replacement must be supplied by a holder of a
Certificate of Authorization or a Quality System Certificate
(Materials).
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Question (2): Is it the intent of Section XI, Division 1 that
replacement reactor vessel studs, washers, and nuts be treated as material or as parts of a nuclear component?
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Question (3): Is it the intent of Article IWA-7000 to include
replacement material in its scope, or was omission of the
word “material” in IWA-7110, IWA-7210(a), and IWA7210(a)(1) intentional?
IWA-7000.
Interpretation XI-1-83-50R, Questions (2) and (3):
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Reply (3): Replacement material is included in the scope of
Reply: No, if the original Construction Code invoked NCA3800.
Interpretation XI-1-89-46R:
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Question (1): Does Section XI, IWA-7210, allow the installation of existing pressure vessels constructed in accordance
with other than the current Edition and Addenda of Section
VIII for use in a nuclear power plant application?
Reply (1): Yes.
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Question (2): Does Section XI, IWA-7210, allow the construction of a Section VIII pressure vessel to other than the
current Section VIII Edition and Addenda when used in a
nuclear power plant application?
Reply (2): Section XI requires the Section VIII requirements
to be met.
Several interpretations address implementation of Section III,
NA-3700/NCA-3800 requirements for obtaining material for use
in Section XI repair/replacement activities. Because Section XI
requires that the Construction Code requirements be met without
any identifying exceptions, even the Section III QA and administrative requirements must be met. An investigation by
Subcommittee XI showed that materials procured from Section III
Quality System Certificate (QSC) Holders are considerably more
expensive than material procured from safety-related suppliers
Question (2): Does Section XI allow an Owner who does not
possess an ASME approved program or has not been qualified by an appropriate ASME Certificate Holder, to qualify
Material Manufacturers or Material Suppliers to provide
material for Section XI repairs or replacements?
Reply (2): No.
Question (3): Is it a requirement of IWA-7310 that Code certified materials be obtained from an ASME accredited
Material Manufacturer and Material Supplier, if the material
is to be used in the manufacture of replacements for use in a
Section XI application?
Reply (3): Yes, if the original Construction Code invoked
NCA-3800. However, the Owner may obtain Code certified
materials from non-ASME accredited Material Manufacturers
or Material Suppliers, if it is noted in his Repair and
Replacement Program and accepted by the regulatory and
enforcement authorities having jurisdiction at the plant site.
Interpretation XI-1-86-55R:
Question: In accordance with Section XI, IWA-4000 and IWA7000, when the Construction Code is Section III, may an
Owner accept the qualification of a non—ASME accredited
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27.8.3
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Alternatively, an item to be used for replacement may meet all or
portions of the requirements of later Editions of the Construction
Code or Section III when the Construction Code was not Section
III, provided that the following requirements are met.
(1) The requirements affecting the design, fabrication, and
examination of the item to be used for replacement are
reconciled with the Owner’s Specification through the
Stress Analysis Report, Design Report, or other suitable method that demonstrates the item is satisfactory
for the specified design and operating conditions.
(2) Mechanical interfaces, fits, and tolerances that provide
satisfactory performance are compatible with system
and component requirements.
(3) Materials are compatible with installation and system
requirements.
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Two comments regarding these interpretations are necessary.
First, in Interpretation XI-1-83-50R, Question (3), the user is cautioned about the wording “noted in his Repair and Replacement
Program and accepted by the regulatory and enforcement authorities having jurisdiction at the plant site.” (See Section 27.6.1.) In
the present regulatory environment existing in the United States,
this wording really means that the Owner obtains approval from the
NRC for an alternative to the Section III requirements. Second, in
Interpretation XI- 1-86-55R, the reply says that the “material is
supplied by the N-Type Certificate Holder or Quality System
Certificate Holder.” This wording actually means either that the
material is shipped from the N-Type Certificate Holder’s or
Quality System Certificate Holder’s facility, or that the N-Type
Certificate Holder or Quality System Certificate Holder has sent
an authorized representative to the organization that supplies the
material and has accepted the material before shipping it to the
Owner. Although this increases the cost of the material, it may be
necessary if the Owner cannot find an N-Type Certificate Holder
or Quality System Certificate Holder who possesses the material
that the Owner needs.
Interpretation XI-1-01-21 provides Section XI clarifications for
a Repair/Replacement Organization transferring materials to different sites:
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Reply: Yes, provided the material is supplied by the N-Type
Certificate Holder or Quality System Certificate Holder, and
the material supply is within the scope of the Certificate.
Reconciliation Requirements
As noted in Section 27.8.1, the requirements for an alternative
to the original Construction Code were first included in
IWA7210(c) in the Summer 1976 Addenda. IWA-7210(c) allowed
replacements to “meet all or portions of the requirements of later
editions of the Construction Code” provided certain requirements
were met. Those requirements permitted use of later editions and
addenda and are referred to as reconciliation requirements. These
requirements did not substantially change from the Summer 1976
Addenda to the 1990 Addenda. The 1989 Edition with 1990
Addenda of IWA-7210(c) reads as follows:
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Material Manufacturer or Material Supplier performed by
the Owner’s designee, if the designee is either an N-Type
Certificate Holder or a Material supplier holding a Quality
System Certificate?
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As can be seen, the reconciliation requirements of IWA7210(c)(1) through (3) were brief, general, and focused on reconciliation of requirements that could affect the design and function
of an item. Implementation of these requirements varied greatly
across the industry. Many users appeared to go to the extreme of
comparing and justifying all changes in each addenda of the
Construction Code. It was clear that other users were not performing the needed evaluations and justifications. For these reasons,
the Working Group on Design Reconciliation rewrote the reconciliation requirements, which greatly expanded and clarified what
needed to be reconciled, and also provided specific reconciliation
requirements for components, materials, parts, and design
requirements. The Working Group generically performed much of
the reconciliation to eliminate many requirements that did not
need to be reconciled by users and also to determine what requirements for reconciliation needed to be included in the Code.
These revised requirements, published in the 1995 Addenda,
consist of IWA-4222 through IWA-4226. Also included in the
1995 Addenda is a definition of reconciliation. Because of a publication error, the text of IWA-4226 and a change to IWA-4221(b)
did not get published in the 1995 Addenda as approved by B&PV
Main Committee. IWA-4226 and the change to IWA-4221(b)
were published as a “Special Errata to the 1995 Edition,” which
was included with Interpretations, vol. 38. However, the Special
Errata should have been to the 1995 Addenda, not to the 1995
Edition. This was noted and corrected by Interpretation XI-1-95-57,
which makes it clear that IWA-4226 and the change to IWA-4221
(b), as included in the Special Errata, are mandatory requirements
to be used with the 1995 Addenda.
The definition of reconciliation describes the intended use of
this term. The definition states that reconciliation is “the process
of evaluating and justifying use of alternative Construction Code
requirements or revised Owner’s Requirements.” The reconciliation requirements included in IWA-4222 through IWA-4226
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Question: When the Construction Code is ASME Section III,
and NA-3700 or NCA-3800 is applicable, may materials purchased, stored, and handled by a Repair/Replacement
Organization at one location be transferred and used in
repair/replacement activities by the same Repair/Replacement
Organization at a different location, when the Repair/
Replacement Organization is not an accredited Materials
Organization or N-Type Certificate Holder, provided that
both locations are covered by the Repair/Replacement
Organization’s quality assurance program?
Reply: Yes.
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The last interpretation noted here regarding the use of
Construction Code requirements is XI-1-86-39R. It provides
clarification on the use of portions of later editions of the
Construction Code and supports the comments made earlier in
Section 27.8.1 about ensuring that all related requirements
are met.
Question: When making replacements in accordance with
Section XI, IWA-7210 allows use of later editions of the
Construction Code either in their entirety or portions thereof.
Is it permissible under Section XI to apply only specific portions of later editions of the Construction Code?
Reply: Yes, provided the requirements of IWA-7210(c)(1),
IWA-7210(c)(2), and IWA-7210(c)(3) and all related
requirements of the respective editions and addenda
are met.
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Reply: Yes, provided Section XI, IWA-7210(c)(2) and (3) are
also met. This interpretation does not address reconciliation
of parts and materials.
However, IWA-4223 does add some new provisions. It allows
components to be supplied to an earlier edition and addenda of
the same Construction Code as the original component provided
the technical requirements of the earlier Construction Code are
reconciled. IWA-4222 provides clarity on the technical requirements that need to be reconciled. Use of a component constructed
to an earlier Construction Code is significant in allowing the
exchange of inventory items between plants with different
editions and addenda of the Construction Code. For Owners
working to editions and addenda of Section XI earlier than the
1999 addenda, Code Case N-567-1 allows the use of earlier
Construction Codes when they are reconciled and may be
beneficial for adoption.
IWA-4224 provides specific requirements for reconciling material produced to requirements other than those used for the original item. Several likely situations were addressed: later editions
and addenda of the material specification; later editions and addenda of the same Construction Code as that of the original item; use
of Section III when the Construction Code is not Section III; earlier editions and addenda of the material specification; and earlier
editions and addenda of the same Construction Code. Use of materials of a different material specification, grade, type, class, alloy
or heat-treated condition than that used in the original item, and
use of the American Society for Testing and Materials (ASTM) or
the American Welding Society (AWS) material specifications in
lieu of Section II material specifications are also addressed in
IWA-4224.
IWA-4224.1(b) and IWA-4224.2(b) note that differences in the
specified material tensile and yield strength must be compared
and evaluated. The evaluation is intended to determine only which
material tensile or yield strengths in the material specifications
were lowered so that the requirements of the next sentence can be
met; it does not imply that increases in the material specification
tensile or yield strengths need to be evaluated. The second sentence in these two paragraphs would be clearer if it read as
follows: “A comparison shall be made of the allowable stress of
the original Construction Code and the allowable stress of the
Construction Code edition and addenda that incorporate the
change in minimum tensile or yield stress from the material
specification.” Sometimes the Construction Code does not change
the material tensile or yield strength or the allowable stress in the
same addenda as the change in the material specification,
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Reply (2): Section XI, Division 1, IWA-7210(c)(1) does not
specifically address documentation requirements. The Owner
is responsible for determining what is necessary to demonstrate suitability of the item with respect to applicable design,
fabrication, and examination requirements. Section XI,
Division 1, IWA-7210(c)(4) requires materials to be compatible with installation and system requirements.
Question: In accordance with Section XI, IWA-7210(c)(1), if
a component meets all the design, fabrication, and examination requirements of the Owner’s specification except Section
III edition and addenda, may it be considered acceptable
without further reconciliation if it is N or NV stamped to a
later Section III edition and addenda?
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Question (2): Does Section XI, Division 1, IWA-7210(c)(1)
apply to documentation requirements for materials being
replaced?
The definition of components in IWA-9000 was revised in the 2004
Edition to remove “item” from the definition to assure materials
and parts were not incorrectly included in the IWA-4223 reconciliation provisions. Changes in weight, configuration, or pressuretemperature rating obviously need to be evaluated and resolved in
accordance with IWA-4311. Not requiring reconciliation of later
Construction Code requirements for replacement components is not
a new position, as noted in Interpretation XI-1-89-41.
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identify the needed actions required to perform an adequate reconciliation. There isn’t a need to discuss each of the requirements
in IWA-4222 through IWA-4226 because most of the requirements can be clearly understood. However, some discussion is
provided in the forthcoming paragraphs on selected provisions of
IWA-4222 through IWA-4226. The basis for these changes and
the reconciliation requirements through the 1999 Addenda can be
found in a Pressure Vessel and Piping (PVP) Conference paper by
W. C. Holston [11].
A clarification regarding reconciliation is included in IWA-4222.
It states that “only technical requirements that could affect materials, design, fabrication, or examination, and affect the pressure
boundary, or core support or component support function, need to
be reconciled.” It further states that administrative requirements
do not need to be reconciled and gives examples of administrative
requirements. For some users, this may appear to be a significant
change, but it is consistent with past practice, as noted in
Questions (2) and (4) of Interpretation XI-1-89-20.
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Question (4): In accordance with Section XI, Division 1, IWA7210, do the nontechnical portions of an Owner’s
Specification (e.g., contractual or administrative requirements) have to be reconciled?
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Reply (4): Section XI does not address reconciliation of nontechnical requirements.
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This interpretation was applicable to the 1983 Edition with the
1983 Addenda. Because Subcommittee XI did address what was
required to be reconciled, the wording of these two interpretations
shows that Subcommittee XI did not intend to have nontechnical
requirements reconciled. Therefore, the specific provision in
IWA-4222 to reconcile only technical requirements was merely a
clarification of the Section XI requirements.
IWA-4222 is clear in pointing out that the administrative
requirements of the Construction Code cannot be eliminated.
Either the administrative requirements of the Construction Code
for the item being replaced or the administrative requirements of
the Construction Code of the item to be used for replacement must
be met. Portions of later administrative requirements may be used,
but a complete set of administrative requirements must be met. A
footnote was added to IWA-4222(a)(2) in the 2000 Addenda to
address the 10CRF50.55a(b)(2)(xvii) modification to Section XI.
The footnote states that the provisions not requiring reconciliation
of administrative requirements do not negate the requirements to
implement the Owner’s QA Program nor does it affect Owner
commitments to regulatory and enforcement authorities.
IWA-4223 provides requirements for reconciling replacement
components. When using later editions and addenda of the
Construction Code or a different Construction Code in accordance
with IWA-4221, no reconciliation of Code requirements is required.
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be compared with the actual material, fabrication, and examination requirements used for the item. For example, if a run of
pipe in the plant is redesigned and a part of the piping run is
replaced, the material, fabrication, and examination requirements of the later Code used to do the redesign would need to
be reviewed to determine which of those requirements affect the
design requirements and to ensure that the existing piping and
the replacement piping meet the requirements that affect the
new design. In this example, a reduced stress intensification factor used in the later design may be dependent on later Code fabrication details used for certain welds. This would need to be
evaluated and justified for use with the existing piping and the
replacement piping.
The 2003 Addenda revised IWA-4226 for reconciliation of
design changes. Prior to the 2003 Addenda, IWA-4226.1 and
IWA-4226.2 addressed using requirements of later editions or
addenda of the Construction Code, or Section III when the
Construction Code was not Section III. In IWA-4226.1, this
allowed an inappropriately abbreviated reconciliation to be performed for use of Section III design provisions for components
constructed to a different Construction Code. The revision to
IWA-4226.1 allowed the abbreviated reconciliation to only be
conducted for use of later design requirements from the same
Construction Code as originally used for the construction of the
component. To facilitate this revision, a new IWA-4226.3 was
included to address reconciliation requirements for design to all
or portions of a different Construction Code, including the appropriate requirements from IWA-4226.1 and IWA-4226.2. IWA4226.1 and IWA-4226.2 were revised to only address the same
Construction Code. These changes in the 2003 Addenda incorporated the provisions of Code Case N-554-3.
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although it should occur in the same addenda. The purpose of
comparing the allowable stresses is to determine if the applicable
Code Committee concluded that the material specification change
would affect the allowable stresses. A change in minimum tensile
or yield strength does not automatically result in a change to
allowable stresses. The changes in the material specification are
evaluated by the Code Committees against the allowable stress
criteria of the Construction Code and may not require a change in
allowable stress.
A special clarification needs to be noted when using Section III
for obtaining material in lieu of using the original Construction
Code. Although IWA-4224.1(b) does not make it clear, it is the
Construction Code allowable stresses that are to be compared.
Comparing the original item’s Construction Code allowable stress
to the Section III allowable stress may not be appropriate because
the criteria for establishing allowable stresses are not the same in
all Construction Codes. If the Construction Code is still being
published, the allowable stress from the original item’s
Construction Code edition and addenda should be used for comparsion with the allowable stress from the later edition and addenda of the same Construction Code—that is, the edition and addenda that incorporated the reduction in material specification tensile
or yield strength.
The third sentence in IWA-4224.1(b) and IWA-4224.2(b)
requires that if the allowable stresses are lowered, the effect of the
reduction in allowable stress on the design of the item shall be reconciled. The reconciliation can include evaluating the design calculations for the item to determine if the item is still acceptable
with the lower allowable stress. In such a case, this would be a
change in design of the item that would require the evaluation and
documentation requirements of IWA-4311 to be met. A possible
conclusion of the reconciliation is that the actual tensile and yield
strengths of the material, as shown on the material test report, meet
the original Construction Code requirements even though the minimum tensile or yield strength of the material specification is lowered—that is, the material often exceeds minimum requirements so
that it meets the original Construction Code requirements.
The 2004 Edition revised IWA-4224.2(c) and IWA-4225(b)
regarding reconciliation of materials, parts, appurtenances and piping subassemblies using technical requirements from earlier editions and addenda of the Construction Code. This revision permits
use of earlier editions and addenda of the Construction Code for
materials and for fabrication of parts, appurtenances, and piping
subassemblies without requiring compliance with the Construction
Code of the installed component as required by the 1993 Addenda
through the 2003 Addenda. The change permits reconciliation of
any technical requirements of the earlier Construction Code to the
Construction Code of the installed component. The change makes
the reconciliation provisions for use of earlier Construction Codes
for material, parts, appurtenances, and piping subassemblies consistent with those applicable to components.
IWA-4225(a) has a reference error that has existed since the
1997 Addenda change to add IWA-4221(b) (discussed in Section
27.8.1). IWA-4225(a) should reference IWA-4221(c) instead of
IWA-4221(b). This correction should be included in the 2008
Addenda.
IWA-4226.2(a) addresses designing to portions of the requirements of a later edition or addenda of the Construction Code.
IWA-4226.2(a) requires that the material, fabrication, and examination requirements of the later Construction Code that are
related to later design requirements (i.e., the design takes credit
for certain material, fabrication, and examination requirements)
27.8.4
Helical-Coil Threaded Inserts
A common problem during maintenance of items is the damage
of threads in threaded connections. This is true of any industry,
not just the nuclear industry, but in the United States the nuclear
industry is unique in that repair/replacement activities performed
are covered by federal law. Consequently, Owners who desired to
use helical-coil threaded inserts to repair damaged threads in
Class 1, 2, or 3 items needed to look to Section XI and the applicable Construction Codes for provisions allowing their use. ASME
Section III addressed use of helical-coil inserts in Interpretation
III-1-81-91R and indicated that Section III neither required nor
prohibited the use of helical-coil inserts in Class 1, 2, or 3 applications. Other Codes had less guidance, and Section XI had no
guidance on the use of these inserts. As a result, Subcommittee XI
prepared Code Case N-496 to allow the use of helical-coil threaded inserts. The Code Case was incorporated into Section XI in
IWA-4451 in the 1995 Addenda. IWA-4451 was relocated to
IWA-4230 in the 2001 Edition.
After some use of the Code Case, a user request resulted in
revision of the Case (N-496-2) and a revision to IWA-4451. The
Code revision was to be published in the 1999 Addenda, but
because of a publishing error, the revision was not included. A
“Special Notice to the 1998 Edition of Section XI,” which contained errata, was published and included with the issuance of vol.
45 of the Section XI Interpretations. The errata, unfortunately,
contained additional errors. The correct version was included in
the 2000 Addenda as errata.
The revision that should have been included in the 1999
Addenda created two changes. The first change removed the
requirement for the supplier of the helical-coil inserts to be
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27.9.1
Analysis and Evaluation for a Design
or Configuration Change
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Section 27.7.3.2 noted that some Owners, and organizations
performing design for Owners, were not maintaining documents
in accordance with IWA-4180 to provide an up-to-date status of
items. IWA-4180 required that the Owner maintain documentation to provide an up-to-date status of items, but the actions
required to maintain this status as well as when those actions were
required were not specified. IWA-4311 was added in the 1995
Addenda and revised in the 1996 Addenda to clarify the requirement in IWA-4180 and to add provisions that specifically recognized the needs of Owners in the maintainance of these documents. IWA-4311 currently provides requirements for changes in
the design and configuration of an item or system, including
material substitutions.
Most Owners do not have records of the design for at least
some of the items within the scope of IWA-4000, for which many
reasons exist. For example, some older Construction Codes did
not identify the need to keep calculations for the life of a plant.
Some Owners assumed that component manufacturers would
keep calculations, but many manufacturers kept calculations only
for the required retention times in the Construction Code, and
some Owners of older plants did not maintain these calculations
even if they did receive them. Section III, before the Summer
1978 Addenda, did not require that all Class 2 and 3 components
be supplied with Design Reports; consequently, not all manufacturers provided their calculations for the design of components.
Some manufacturers did not provide complete design calculations
because of proprietary designs. In addition, standard piping
flanges and fittings and standard B16.34 valves may not be
required to have calculations.
As a consequence to this lack of design records, IWA-4311
acknowledged that Owners would have calculations for some
items only. IWA-4311 (a) provides the requirements when existing calculations are available; IWA-4311(b) provides requirements when calculations are not available.
IWA-4311 (a) requires the organization performing the design
or configuration change (i.e., Owners or organizations that perform design activities for Owners) to evaluate the extent of the
design or configuration change and determine if the extent of the
change requires reanalysis to determine its acceptability. Some
changes are not complex and reanalysis is not required; in such
cases, an evaluation needs to be performed and documented that
provides the basis for acceptability of the change. Changes that
cannot be accepted by an evaluation require a reanalysis to be performed in accordance with the Construction Code requirements.
This does not imply a complete reanalysis, but only a reanalysis
that is sufficient to determine the acceptability of the change. The
methods used in the evaluation or reanalysis must comply with
the methods and requirements of the original Construction Code.
Later Construction Codes or Owner’s Requirements can be used
if the requirements of IWA-4220 are met, including the reconciliation documentation required by IWA-4222 through IWA-4226.
The evaluation or reanalysis is required to document that the proposed change meets either the Owner’s Requirements and the
Construction Code or the alternative provisions of Section XI.
These alternative provisions acknowledge that Section XI has
included analytical evaluation techniques, such as IWB-3600 and
IWB-3700, IWA-4133, IWA-4340, or Section XI Code Cases
such as N-513-2 and N-597-2 (see Section 27.9.3 for a discussion
of IWA-4340 and Code Cases N-513-2 and N-597-2) that may be
used in lieu of the Construction Code requirements for evaluating
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evaluated for compliance with Section III, NCA-3800, or
10CFR50, Appendix B. Instead, it required that the inserts be purchased in accordance with the Owner’s or Repair/ Replacement
Organization’s QA Program, which allowed use of the full
procurement provisions (e.g., the use of commercial grade dedication for nuclear applications) included in their QA Programs.
The second change addressed problems in the documentation of
the inserts. Determining the heat-treated condition and the
mechanical properties of the inserts is not feasible after the
inserts’ final forming because of the manufacturing effects. The
Committee determined that it was sufficient for the mechanical
properties and heat treated condition to be reported before final
forming and revised the requirements accordingly. Unfortunately,
this is one of the changes not correctly noted in the “Special
Notice to the 1998 Edition of Section XI” discussed in the preceding paragraph. The 2000 Addenda correctly reflected the
intent described here.
IWA-4230(a) requires that the helical-coil threaded insert satisfy the design requirements of the Construction Code for the loadings to be applied to the threaded connection. Some of the materials used in manufacturing inserts are not approved for use in the
Construction Code. As a result, no Code allowable stresses have
been established for these materials. Therefore, Section XI provides criteria for determining allowable stresses to be used with
the design requirements established by the Construction Code.
IWA-4230(b) and (c) address requirements for quality assurance
and documentation requirements to be used in obtaining helicalcoil threaded inserts. Because manufacturers of helical-coil
threaded inserts provide specific instructions for drilling and
threading the hole for the insert and for installing the inserts,
IWA-4230(d) simply requires the inserts to be installed in accordance with the manufacturer’s instructions.
DESIGN ASSOCIATED WITH
REPAIR/REPLACEMENT ACTIVITIES
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Section XI requirements for repair/replacement activities traditionally refer back to the Construction Code for design requirements. The reference back to the original Construction Code and
Owner’s Requirements (subject to certain additions and limitations) for performance of repair/replacement activities is an
important philosophy. It is appropriate because of the difficulty
and cost in trying to upgrade an existing component or system to
later Code requirements and also because of the continued acceptability of the original Construction Code and Owner’s
Requirements for providing an acceptable level of safety.
However, an operating nuclear power plant has some needs that
cannot be addressed by a simple referral back to the Construction
Code. Additionally, Construction Codes are concerned only with
new construction and do not adequately address all aspects of
maintaining the design of items in an operating nuclear power
plant.
Because of the recognization that some provisions needed to be
added to address the specific needs of an operating plant, design
provisions were added in the new Subarticle IWA-4300 in the
1995 Addenda. IWA-4300 does not replace the Construction
Code requirements; instead, it addresses how to use those
Construction Code requirements in an operating plant and how to
maintain important design documents that provide an up-to-date
status of items. Additionally, IWA-4300 has provisions not
addressed by the Construction Code, such as rerating.
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that affect the evaluation or new analysis are required to be
processed in accordance with IWA-4311(a). As required for the
evaluations and reanalysis of IWA-4311(a), IWA-4311(c) requires
that an evaluation and a new analysis performed in accordance
with IWA-4311(b) shall be reviewed and certified in accordance
with the requirements of the Construction Code and Owner’s
Requirements.
IWA-4311 (d) was added to more clearly state the requirements
in IWA-4180(c) for keeping Design Specifications and Design
Reports current to provide an up-to-date status of an item. It
requires the affected documents of any design or configuration
change that deviates from the Owner’s Requirements, Design
Specification, or Design Report to be revised or updated in accordance with IWA-4180(c). A new IWA-4311(e) replaced
IWA4180(c) in the 2003 Addenda.
IWA-4311(d) was added in the 1997 Addenda. However, the
1997 Addenda failed to identify this change as an erratum. It was
approved as part of the same action item that made the changes to
IWA-4311 in the 1996 Addenda and should have been published
with the 1996 Addenda. Owners working to the 1996 Addenda
should therefore include IWA-4311(d) in the 1997 Addenda as
part of their Repair/Replacement Program. Also, Owners need to
ensure that contractual arrangements with organizations that perform the designs for them require such organizations to comply
with the requirements of IWA-4311(d).
As discussed in Section 27.7.3.2, IWA-4180(b)(1) through (b)(3)
and IWA-4180(c) were moved to a new paragraph IWA-4311(e) in
the 2003 Addenda. No change in requirements was associated.
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operating plant conditions, including degraded and nonconforming conditions. The provisions in IWA-4311 do not allow Owners
or the organizations performing design for the Owners to make
changes or perform evaluations and/or reanalysis that do not comply with the Construction Code or Section XI.
IWA-4311 (a) also requires that the evaluation or reanalysis be
traceable in accordance with IWA-4311(e) (IWA-4180(c) prior to
the 2003 Addenda). This refers to the requirement of maintaining
the up-to-date status of items and also the provision in IWA-4311(e)
that allows a linking process that provides traceability to and from
the original documents and the documents that revised or updated
the original documents (see Section 27.7.3.2).
IWA-4311(c) requires that evaluations and reanalysis shall
be reviewed and certified in accordance with the requirements of
the Construction Code and Owner’s Requirements. This refers to
the requirements in Section III, in the Draft Pump and Valve
Code, and in B31.7, to name a few, that require Design
Specifications and Design Reports to be certified by a Registered
Professional Engineer. Here, Subcommittee XI concluded that if
the Construction Code requires the services of a Registered
Professional Engineer, to ensure understanding of and compliance
with the requirements of the Construction Code, the requirement
should pertain to an evaluation or reanalysis performed to change
the documents.
IWA-4311(b) provides requirements when an analysis for the
item being changed is not available. Some typical reasons for this
condition were noted previously. Similar to the provisions in
IWA-4311 (a), the Owners or organization performing design
activities for Owners must evaluate the extent of the design or
configuration change and determine if the extent of the change
requires analysis to determine its acceptability. Some changes are
not complex and a new analysis is not required; in such cases, an
evaluation needs to be performed and documented that provides
the basis for acceptability of the change. Changes that cannot be
accepted by an evaluation, require a new analysis to be performed
in accordance with the Construction Code requirements. This
does not imply a complete analysis, but only an analysis that is
sufficient to determine the acceptability of the change. The methods and requirements used in the evaluation or new analysis must
comply with the methods and requirements of the original
Construction Code. Later Construction Codes or Owner’s
Requirements may be used if the requirements of IWA-4220 are
met, including the reconciliation documentation required by IWA4222 through IWA-4226. The evaluation or new analysis is
required to document that the proposed change meets the Owner’s
Requirements and the Construction Code or the alternative provisions of Section XI. These alternative provisions acknowledge
that Section XI has included analytical evaluation techniques, such
as IWB-3600 and IWB-3700, IWA-4133, IWA-4340, or Section
XI Code Cases such as N-513-2 and N-597-2 (see Section 27.9.3
for a discussion of IWA-4340 and Code Cases N-513-2 and
N-597-2) that may be used in lieu of the Construction Code
requirements for evaluating operating plant conditions, including
degraded and nonconforming conditions. The provisions in IWA4311 do not allow Owners or the organizations that perform the
design for the Owners to make changes or perform an evaluation
or new analysis that does not comply with the Construction Code
or Section XI.
IWA-4311(b) requires that the evaluation or new analysis be
treated the same as a Design Report and maintained as required
by IWA-4311(e) (IWA-4180(c) prior to the 2003 Addenda).
Subsequent changes to the design or configuration of this item
27.9.2
Rerating
Changes involving the rerating of items are becoming more frequent as Owners extend the life of older plants and make system
changes to both older and newer plants. Before the 1995
Addenda, Section XI did not have provisions for rerating items.
IWA-4312 was added in the 1995 Addenda to provide requirements for rerating; consequently, these requirements made rerating a repair/replacement activity. A definition for rerating was
also added to IWA-9000 as part of the action to add rerating; it
reads as follows: “A nonphysical change to an item or piping system done by changing its design ratings (e.g., internal or external
pressure or temperature). Rerating covers pressure boundary
items, core supports, and component supports.”
In the 1999 Addenda, an editorial renumbering for the rerating
requirements was made from IWA-4312 to IWA-4330, and one
change was made to the requirements. That change allowed later
editions and addenda of the Construction Code, or later different
Construction Codes, to be used for rerating. In the 2003 Addenda,
a change was made to eliminate the requirements to document
rerating of component supports on NIS-2 Forms.
IWA-4331 requires that rerating comply with the applicable
design requirements of the Construction Code and Owner’s
Requirements. It allows use of later Construction Code editions
and addenda, or later different Construction Codes, provided the
requirements of IWA-4221 are met. Additional provisions require
that overpressure protection be evaluated in accordance with the
Construction Code requirements; that the rerating be evaluated
and analyzed in accordance with IWA-4311; that Form NIS-2 be
completed to document the rerating except for rerating of component supports; and that a new nameplate be attached as close as
practical to any existing nameplates that the rerating affects.
IWA-4331(c) notes that Owner’s Requirements are to be
revised or updated when necessary. This includes revising the
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Except as noted in the following paragraph, the requirements of
IWA-4340 were added to Section XI to clarify the concept included in Interpretation XI-1-92-31. The addition of IWA-4340 should
not be considered representative of any new Code provisions that
for the first time allow mitigation of defects by modifications.
Owners that meet the Construction Code and Section XI repair/
replacement activity requirements do not need to use IWA-4340
to perform these types of modifications. However, Owners are
cautioned to ensure that the root cause of the degradation is
understood and that the modification contains or isolates not only
the degraded area, but also the projected growth of the degraded
area. Owners should also monitor the growth to ensure that the
extent of the growth remains within the projections used in the
modification. It is important to note that Subcommittee XI
clarified through other interpretations (XI-1-95-25 and XI-1-9529, discussed in Section 27.10.3) that the defect does not need to
be removed as noted in condition (a) of Interpretation XI-1-92-31.
Interpretation XI-1-04-10 specifically confirms two important
points made in the previous paragraph and is as follows:
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Other Design Provisions
Question (1): IWA-4340 requires that the flaw be characterized and evaluated to determine its cause and projected
growth; the modification must meet the Construction Code
for provision of structural integrity of the item such that it no
longer relies on the defective area; and in lieu of reexamination of the defective area, the Owner is required to prepare a
plan for additional examination to detect propagation of the
flaw beyond the limits of the modification, and where practical, to validate the projected growth. When the provisions of
IWA-4340 are used for mitigation of defects by modification,
is it a requirement that the defect be removed or reduced to an
acceptable size?
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There are two other subsubarticles (no, this is not a misspelled
word, for the Code uses its own made-up word to refer to requirements with numbering systems such as IWA-4320; see the
Section XI Preface) in IWA-4300 that have not yet been discussed. IWA-4320 contains requirements for Class 1 piping
mechanical joints. These provisions were added in the Summer
1976 Addenda along with the other requirements for replacements. The requirements are Construction Code-type requirements, similar to Section III requirements. The requirements typically apply to older plants that did not have similar requirements
imposed during their construction.
The other subsubarticle is IWA-4340, “Mitigation of Defects By
Modification.” Because of publishing errors, IWA-4340 was not
included in the 1999 Addenda as intended. It was published in a
Special Errata, along with other corrections to the 1999 Addenda,
titled “Special Notice to the 1998 Edition of Section XI,” included
with the issuance of vol. 45 of Section XI Interpretations. It was
then published in the 2000 Addenda as errata.
The concept included in IWA-4340 is that the modification provides for the structural integrity of the item so that it no longer
relies on the defective area, including projected growth of the
defect. A classic example of this type of modification is welding a
branch connection to the outside of a degraded pipe so that the
degraded area, including the projected growth of the degraded
area, is entirely contained within the area of the branch connection. The branch connection is capped or flanged to provide a new
pressure boundary without any pressure-retaining contribution
from the degraded area of the run pipe. In essence, the degraded
area could be gone as if it were a real branch connection. Utilities
in the United States have performed this type of modification by
meeting all of the Construction Code requirements for the
modification and also by meeting all of the Section XI repair/
replacement activity requirements, thereby maintaining compliance
with federal regulations. This was confirmed by Interpretation
XI-1-92-31, which follows.
Reply: Yes.
AS
27.9.3
provisions of the Construction Code or Section III are met for
the component with the closure device installed.
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Design Specification because Owner’s Requirements is a generic
term that includes the Design Specification.
IWA-4332 requires that inservice flaws previously accepted by
analytical evaluation in accordance with IWB-3000, IWC-3000,
IWE-3000, or known wall-thinning be evaluated in accordance
with IWA-4311 to ensure that the rerating conditions do not
adversely affect previous evaluations. Requirements for additional
examinations and pressure tests are included in IWA-4333 and
IWA-4334.
A related change that affects rerating was made in IWA4150(c) in the 1997 Addenda. That change does not require a
Repair/ Replacement Plan to be prepared for repair/replacement
activities that involve only design changes, of which rerating is
included.
Question: If through-wall leakage is found during a system
pressure test, are the following conditions an acceptable corrective action under Section XI, IWA-5250:
(a) the flaw is removed;
(b) a closure device (e.g., branch connection, weldolet)
meeting the requirements of IWA-4000/IWA-7000 and
the Construction Code or Section III is installed; and
(c) an evaluation considering the extent of the original flaw
is performed demonstrating that the structural integrity
Reply (1): No.
Question (2): Does the 1980 Edition through the 1998 Edition
with the 1999 Addenda of Section XI, IWA-4000 or IWA7000, as applicable, permit defective pressure-retaining
material to be replaced by modification meeting the
Construction Code provisions for structural integrity of the
item, such that it no longer relies on the defective area without removal of the defect?
Reply (2): Yes.
IWA-4340(c) does provide one new provision that has not been
previously allowed. The information presented in the preceding discussion was predicated on meeting all of the Construction Code
and Section XI requirements. IWA-4530(a) requires that a new preservice examination be performed before the item is returned to service. The mitigation of a defect by modification may preclude
access for performance of a preservice examination after the
repair/replacement activity; in such a case, the requirements of
Section XI cannot be met, and this type of repair/replacement activity cannot be performed. IWA-4340(c), however, provides an alternative to performing the preservice examination. It requires the
Owner to prepare a plan for additional examinations to detect propagation of the flaw beyond the limits of the modification and, where
possible, to validate the projected growth. The 2000 Addenda of
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WELDING, BRAZING, METAL
REMOVAL, FABRICATION
AND INSTALLATION
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the Case are focused on the integrity of the vessel or tank against
gross failure. Additional provisions for periodic inspection and
leakage monitoring are included to assure that analysis assumptions
are conservative for the operating conditions. Errata to Case N-705
was included in Supplement 4 of the 2007 Nuclear Case book to
correct errors in the initial publication. Case N-705 is an extension
of two similar approaches for piping, including NRC Generic
Letter 90-05 regarding temporary non-code repairs of Class 1, 2,
and 3 piping, and Case N-513-2 discussed above. Due to the recent
publication of this Case, the NRC has not yet evaluated it for inclusion in Regulatory Guide 1.147.
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The IWA-4000 rewrite in the 1995 Addenda organized repair/
replacement activity requirements by functional areas, similar to
the Section III organization. IWA-4400 in Section XI compares
roughly to NX-4000 in Section III in that they both cover activities common to fabrication and installation. During the rewrite, no
simple title seemed to capture the pertinent scope of IWA-4400;
thus it was given the following title to reflect the work activities
covered: “Welding, Brazing, Metal Removal, and Installation.”
However, several changes were made since the 1995 Addenda
that have affected the scope of IWA-4400. First, defect removal
requirements were moved to IWA-4600 in the 1996 Addenda;
second, new defect removal requirements were added to
IWA-4400 in the 1997 Addenda; third, the 1999 Addenda editorially changed the scope of IWA-4400 from “metal removal” back
to the term “defect removal”; fourth, the 2001 Edition substantially
changed and reorganized IWA-4400 requirements including
another IWA-4400 title change; and fifth, the 1997 Addenda
included a change that allowed Owners to fabricate parts.
Unfortunately, the change allowing fabrication of parts was
included in IWA-4143(a), but it did not make the necessary
clarifications to the rest of IWA-4000, including the clarification
that fabrication of parts was also included in the scope of IWA4400. The appropriate Code changes and clarifications regarding
this subject, including the addition of fabrication to the titles of
IWA-4400 and IWA-4411, were published in the 2005 Addenda.
(See discussion in Section 27.5.3 for further information regarding the clarifications on fabrication.)
The changes noted in the previous paragraph have resulted in
three changes to the paragraph numbering of IWA-4400 since the
IWA-4000 rewrite in the 1995 Addenda. Unfortunately, this creates confusion for users of Section XI. However, the changes have
resulted in improvements in the clarity and usability of IWA-4000.
The 2001 Edition retitled IWA-4400 by changing defect removal
to metal removal and substantially changed and reorganized IWA4400. As a result, Sections 27.10.1 through 27.10.3 were expanded
in the second edition of the Companion Guide to add discussion of
the 2001 Edition changes while retaining the first edition discussion of the 1999 Addenda. This should be beneficial to Owners
and Repair/Replacement Organizations working to the 1997
Addenda through 2000 Addenda as well as those working to the
2001 Edition or later. Section 27.10.7, Helical-Coil Threaded
Inserts, in the first edition was moved to Section 27.8.4 to reflect
the 2001 Edition paragraph number changes.
Before looking at the specific requirements of IWA-4400, an
additional clarification needs to be made regarding the scope of
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Section XI containing IWA-4340 was approved by the NRC in
2002 for use in the United States. However, in 2004, the NRC prohibited use of IWA-4340 when using the 2001 Edition or later
addenda through the 2003 Addenda.
Because the present section of this book covers “other design
provisions,” it is an appropriate location to discuss three important
Section XI Code Cases: N-513, N-597, and N-705, as well as
later revisions of N-513 and N-597. These Code Cases contain
provisions for analytically evaluating degraded conditions in piping, pressure vessels, tanks, and heat exchangers. As Code Cases,
these provisions are not mandatory, but instead are alternatives to
Code requirements. (See the section 27.1 for a discussion on
Code Cases.)
Code Case N-513 provides provisions to temporarily accept
defects (including through-wall defects) in Class 3 piping without
a repair/replacement activity for a time not to exceed the time to
the next scheduled outage. The Case is limited to moderateenergy Class 3 pipe and tube (with a maximum operating temperature not to exceed 200F and with a maximum operating pres1
sure not to exceed 275 psig), and up to a distance of (Rt)2 into
adjoining fittings and flanges. The Case specifies actions to be
taken to characterize the defect, the analysis to be performed to
determine integrity of the item with the defect, the performance of
periodic examinations to monitor the defect growth, and the performance of augmented examinations to assess degradation in
other locations. Although the Case is conservative, it is very
beneficial to Owners by providing a mechanism to temporarily
accept through-wall leakage without needing to take the system
out of service to perform a repair/replacement activity. In the
United States, the NRC allowed Case N-513 to be used by inclusion in 10CFR 50.55a(b)(2)(xiii) of the federal regulations without the requirement to submit a relief request, as previously
required by the NRC. Effective November 1, 2004, the NRC
removed Case N-513 from 10CFR 50.55a(b)(2)(xiii) because it
had been added to Regulatory Guide 1.147, Rev.13 and no longer
needed to be specifically included by reference in the regulation.
Case N-513-1, the first revision to N-513, expanded the scope
of the Case to also include Class 2 moderate energy piping and to
address stress corrosion cracking evaluation techniques. Case
N-513-2 significantly improved the defect evaluation methodology in the Case. It was rewritten to use the 2002 Addenda Section
XI improvements in flaw evaluation methodology which also
combined Section XI Appendices C and H. Code Case N-513-1
was conditionally approved for use by the NRC in Reg. Guide
1.147, Rev. 14. Code Case N-513-2 was approved for use by the
NRC in Reg. Guide 1.147, Rev. 15 [17]. Users should consider
adoption of Case N-513-2 as it provides important tools for temporary acceptance of defects in piping.
Code Case N-597 provides provisions for the analytical evaluation of Class 1, 2, and 3 carbon and low-alloy steel piping items
with internal and external wall-thinning as a result of corrosion,
including flow-accelerated corrosion. It provides the evaluation
techniques and acceptance criteria to be used and was developed
for use primarily on systems affected by flow-accelerated corrosion. Case N-597-1 and N-597-2 provide significant expansion of
the scope of the original N-597. Case N-597-2 was accepted by
the NRC with conditions in Regulatory Guide 1.147 [17].
Code Case N-705 was published in Supplement 11 of the 2004
Nuclear Case book and provides evaluation rules and criteria for
temporary acceptance of degradation, including through-wall
degradation, in moderate energy, ferritic and austenitic, Class 2 and
3 vessels, including heat exchangers, and tanks. The provisions of
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1978
Reply (2): Yes.
IE
Interpretation XI-1-83-42:
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Question (1): Is a repair program required when making an
installation of IWA-7000 replacement by welding or brazing
in accordance with the 1977 Edition of Section XI with
addenda up to and including the Summer 1978 Addenda, and
later addenda up to the 1983 Edition of the Code?
Reply (1): Yes.
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Question (2): Is it a requirement of Section XI that repairs
and installation of replacements by welding or brazing to
component supports on Code Class 1, 2, and 3 systems be
performed with a Repair Program [IWA-4130(a)]?
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(Summer
Y
Reply: The requirements of the original Construction Code
shall apply when Section XI repairs and replacements are
made by brazing.
Interpretation XI-1-86-23 Question (2)
Addenda through Summer 1985 Addenda):
27.10.1.1 General Requirements –1997 Addenda Through
2000 Addenda IWA-4410(a) provides directions on how to use
IWA-4400. Three paths are immediately encountered. In the first
path, if the repair/replacement activity can be completed by meeting the referenced requirements of the Construction Code, IWA4410 requires that the Repair/Replacement Organization use IWA4410, IWA-4420, IWA-4440, and IWA-4460 to determine the
welding, brazing, defect removal, and installation requirements.
For certain repair/replacement activities, however, the
Construction Code provisions cannot be met; it is for this reason
that Section XI contains alternative welding methods for performing the repair/replacement activity. These alternative welding
methods are found in IWA-4600 and are discussed briefly in
Section 27.12. However, much of IWA-4400 is also to be used in
conjunction with IWA-4600. Therefore, when this second path
consisting of alternative welding methods is used, IWA-4410
requires that the Repair/Replacement Organization use IWA-4410,
IWA-4430, IWA-4440, and IWA-4460. (Note that IWA-4420 does
not apply.) The third path provides for welding, brazing, and other
techniques used in heat exchanger tube plugging or sleeving. For
heat exchanger tube plugging or sleeving, the repair/replacement
activity is to be performed in accordance with IWA-4410(b) and
(c) and also with IWA-4700. IWA-4410(b) and (c) provide standard requirements for storage and handling of welding electrodes,
flux, and other welding materials.
AS
Question: Under what rules of Section XI, Division 1, may
repairs (IWA-4000) and replacements (IWA-7000) by brazing
be used?
2000 Addenda. In addition, the second edition was expanded to
include discussion of the 2001 Edition changes through the 2004
Edition requirements. The third edition of the Companion Guide
updated the latter discussion to current requirements.
M
IWA-4400. The title of IWA-4400 makes it clear that brazing is
included. Although parts of IWA-4400 clearly identify requirements for brazing, IWA-4440 and other places in IWA-4000 inadvertently use only the term welding. This is an area that the Code
Committee needs to clarify through additional Code revisions.
Before the 1995 Addenda, there were even fewer provisions for
identifying requirements for brazing, bringing into question
whether brazing was considered a repair or replacement.
However, the intent of Section XI was clarified in three interpretations that clearly show that brazing has been considered a repair
or replacement as far back as the Summer 1978 Addenda. For
users working to Section XI editions and addenda earlier than the
1995 Addenda, these interpretations may be very important.
Interpretation XI-1-86-47 (1986 edition):
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From these interpretations, it is apparent that Subcommittee XI
intended brazing to be covered by the repair and replacement
requirements at least as far back as the Summer 1978 Addenda.
However, the details were not very clear. The indication in
Interpretation XI-1-86-47 that the details of the original
Construction Code were to be used for brazing provides some
needed clarification of the applicable requirements, but it also creates some additional problems. For example, because Section XI
requirements for pressure testing are to be used in lieu of the
Construction Code pressure testing requirements, not all requirements of the Construction Code are to be used for brazing. (For a
discussion of the pressure testing requirements for brazing, see
Section 27.11.3.1.) Revisions to IWA-4000 in later editions and
addenda are expected to improve the clarity of the applicable
requirements for brazing.
27.10.1 General Requirements
As noted in section 27.10, section 27.10.1 retained the
Companion Guide first edition discussion of the general requirements contained in IWA-4410 in the 1997 Addenda through the
27.10.1.2 General Requirements –2001 Edition and Later
The 2001 Edition substantially reorganized the content of IWA4410, IWA-4420, and IWA-4430, changed IWA-4410, and added
new paragraphs IWA-4411 through IWA-4413. IWA-4410 was
rewritten to make its contents consistent with the revised title of
IWA-4400. It was also revised to clarify that mechanical metal
removal not associated with defect removal was not within the
scope of IWA-4400. Mechanical metal removal not associated
with defect removal was excluded because it is not a special
process that would require controls similar to those needed for
welding, brazing, or thermal metal removal. IWA-4400 retained
controls in IWA-4462 for those mechanical metal removal activities associated with defect removal because those controls are
needed to assure defect removal and appropriate NDE.
As part of the 2001 Edition changes, IWA-4411 was added to
consolidate applicable requirements for welding, brazing, and
installation. It also clarifies the Construction Code requirements
that apply and the Section XI requirements that modify or provide
exceptions to the Construction Code requirements for welding,
brazing and installation by welding or brazing. Provisions for
storage and baking of filler materials previously in IWA-4410
were moved to IWA-4411(h) (and subsequently moved to IWA4411(i) in the 2005 Addenda when a new paragraph (h) was
added to reference a new Nonmandatory Appendix Q for stainless
steel weld overlay, as discussed below). Portions of the provisions
for Construction Code and Owner’s Requirements previously in
IWA-4421 were moved to an IWA-4411 introductory paragraph
and to IWA-4411(a) and (b).
IWA-4412 and IWA-4413 were added to require defect removal
to be in accordance with the revised IWA-4420 and metal removal
by thermal methods to be in accordance with the existing
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corrosion cracking and fatigue. The 2007 Edition included the
revision to Appendix Q to make these changes. Code Case
N-504-4 was included in Supplement 10 of the 2004 Nuclear
Code Case book and is the current version of the Case.
For Owners who may still be implementing Case N-504-2,
there are two interpretations that should be noted. The first is
XI-1-04-11, which clarifies a couple of references to Section XI
paragraphs. It states:
AS
Reply: Yes.
M
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Question: When applied to the 1995 Edition with the 1996
Addenda through the 2001 Edition, is it the intent of Code
Case N-504-2, para. (g)(2) to apply the evaluation requirements for SAW and SMAW weld metal from Tables IWB-36411 and IWB-3641-2 in lieu of Tables IWB-3641-5 and IWB3641-6?
The second is XI-1-04-08, which clarifies the applicability of
Construction Code examination requirements to the weld reinforcement applied in accordance with N-504-2. The interpretation
states:
Y
Question: Is it a requirement of Code Case N-504-2 that the
weld reinforcement repair be examined in accordance with
the requirements of the Construction Code identified in the
applicable Repair/Replacement Plan?
R
IWA-4461, thereby bypassing the IWA-4411 requirement that
invoked the use of the Construction Code. The addition of these
new paragraphs accomplishes much the same as the requirements
in IWA-4421(a) in the 1997 Addenda through the 2000 Addenda,
in which defect removal and metal removal by thermal methods
are performed in accordance with the specified Section XI
requirements rather than any similar requirements in the
Construction Code.
The reorganization of requirements moved the content of IWA4430 in the 1997 Addenda through the 2000 Addenda to
IWA-4411(e) and (f), resulting in the deletion of IWA-4430.
The 2005 Addenda added Nonmandatory Appendix Q, Weld
Overlay Repair of Class 1, 2, and 3 Austenitic Stainless Steel
Piping Weldments. IWA-4411(h) was added to allow the use of
this Appendix for stress corrosion cracking in stainless steel weldments. When Appendix Q is used, the nondestructive examinations of the Appendix apply in lieu of IWA-4520 and IWA-4530.
Appendix Q incorporated Code Case N-504-3, and its prior versions, into Section XI. However, several changes and additions to
the content of the Case were made, including expanding the NDE
methods and acceptance criteria for the overlay and adding inservice inspection requirements (extent and frequency of examinations and sample expansion provisions). A revision was made to
the design section of Appendix Q in the 2006 Addenda to correct
inappropriate changes from the Code Case design provisions.
Code Case N-504-3 (and its earlier versions) addresses the reduction of a defect to a flaw of acceptable size by the deposition of
weld reinforcement (weld overlay) on the outside surface of the
piping. It includes provisions for addressing defects that are
through-wall leaks. The Case provisions were derived from the
technique commonly used for the repair of intergranular stress
corrosion cracking on boiling water reactor piping. The Case
requires that the weld overlay be applied 360 deg. around the circumference of the piping.
The NRC has allowed conditional use of Code Case N-504-2
and N-504-3 in Regulatory Guide 1.147, Rev. 14 and 15, requiring that the provisions of Appendix Q must also be met. These
Cases were modified by Owners and were combined with Case
N-638-1 as relief requests, which were submitted to the NRC for
approval as the basis for installation of weld overlays on Alloy
82/182 dissimilar metal welds in both PWR and BWR plants.
However, the need for repair of primary water stress corrosion
cracking in PWR components lead ASME Section XI committee
personnel working with EPRI and industry to start work on a
Code Case to specifically address weld overlays for Alloy 82/182
dissimilar metal welds.
As a result, Code Case N-740 was expeditiously prepared to
specifically address repair of dissimilar metal welds by weld overlays over existing Alloy 82/182 weld joints, where base materials
may involve carbon steel, low alloy steel, stainless steel or Alloy
600. This Case started with provisions from Code Case N-504-2
and Appendix Q, which were only for stainless steel materials,
and was expanded to cover the specific needs for use of Alloy
52/152 overlay filler materials over the noted different base materials. Revisions soon followed to address industry experience in
use and to include mitigation to preclude flaw initiation as well as
repair to preclude flaw growth. Case N-740-2 is the latest version
and should be approved by ASME in 2008.
During the development of proposed Code Case N-740, the
need to correct and clarify Appendix Q and Code Case N-504-3
became apparent. It was also recognized that Appendix Q should
allow the use of weld overlay repair of defects from both stress
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Reply: No.
27.10.2 Construction Code Requirements
As noted in section 27.10, section 27.10.2 retained the
Companion Guide first edition discussion of the Construction
Code requirements contained in IWA-4420 in the 1997 Addenda
through the 2000 Addenda. In addition, the second edition was
expanded to include discussion of the 2001 Edition changes
through the 2004 Edition requirements. The third edition of the
Companion Guide updated the latter discussion to current requirements. IWA-4420 in the 1997 Addenda through the 2000 Addenda
contains requirements for deciding which Construction Code to
use, how to use the Construction Code, and when Section XI
requirements supersede the Construction Code requirements. In
the 2001 Edition changes to IWA-4400, the similar requirements
are located in IWA-4411 through IWA-4413.
The provisions of IWA-4421 in the 1997 Addenda through the
2000 Addenda and IWA-4411 through IWA-4413 in the 2001
Edition and later edition and addenda are generally consistent
with the philosophy used throughout IWA-4000: the requirements
used for the manufacture and installation of the original item may
continue to be used for repair/replacement activities throughout
the life of the item. However, IWA-4421(a) in the 1997 Addenda
through the 2000 Addenda and IWA-4411 through IWA-4413 in
the 2001 Edition and later edition and addenda do have some
requirements that are to be used in lieu of the Construction Code
requirements; these are discussed in subsequent paragraphs.
Contracts and specifications used for the construction of a power
plant often specified a Construction Code for the installation
of items in the plant that did not necessarily match the
Construction Code used for the manufacture of components,
parts, and materials that were to be installed. Therefore, the
applicable Construction Code is dependent on the specifics of the
repair/replacement activity to be performed. For example, a welded repair on a valve body will use the Construction Code used to
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Y
AS
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IWA-4421(c) in the 1997 Addenda through the 2000 Addenda
and IWA-4411(b) in the 2001 Edition and later both allow use of
revised Owner’s Requirements, provided they are reconciled in
accordance with IWA-4222. Documentation of the reconciliation
is required. This requirement to reconcile and document the reconciliation of revised Owner’s Requirements should easily be
met for Owners who work to Construction Codes that require
Design Specifications. IWA-4180(c) prior to the 2003 Addenda
and IWA-4311(e) in the 2003 Addenda and later editions and
addenda require documentation, such as Design Specifications
(i.e., Owner’s Requirements), to be kept up to date to provide a
current status of the item. To accomplish this task, an Owner
needs to evaluate the revision of a Design Specification in accordance with the Owner’s QA Program, which includes a design
change process. This process ensures that the change is acceptable for the items covered by the Design Specification. The
Owner’s design change processes should be adequate to meet a
requirement to reconcile changes in the Owner’s Requirements,
especially if the applicable Section XI reconciliation requirements are considered during the design change process.
Additionally, documentation prepared by the Owner’s design
change process should be adequate as reconciliation documentation; in such cases, Owners do not need to prepare additional
documentation. The revision of the Design Specification
becomes the “current design” for the items covered by the
Design Specification (i.e., the revised Owner’s Requirements).
When a repair/replacement activity is to be performed on an
item, there is no need to reconcile the current design against the
original Design Specification because this task already has been
accomplished. However, reconciliation of changes to the original
Owner’s Requirements is required to be performed and documented by Owners of older plants for which Design
Specifications were not required and when the sources of the
Owner’s Requirements were not kept up to date.
The discussion to this point has addressed the requirements for
determining the Construction Code and Owner’s Requirements to
be used when performing welding, brazing, defect removal, fabrication, and installation activities. IWA-4421(a) in the 1997
Addenda through the 2000 Addenda also contains two important
exceptions that were added in the 1997 Addenda. These exceptions are to be used in lieu of the requirements of the Construction
Code determined in accordance with the previously discussed
requirements. The 2001 Edition revision to IWA-4410 and IWA4420 and the addition of IWA-4412 and IWA-4413 accomplish
much the same as the following two exemptions for the earlier
addenda. The 2001 Edition changes do not invoke the
Construction Code requirements for mechanical defect removal or
thermal metal removal, nor for the examination of defect removal
areas. Therefore, the exemptions aren’t needed for the 2001
Edition and later editions and addenda.
The first exception is the requirement that IWA-4460 be used in
lieu of Construction Code requirements for mechanical and thermal metal removal. This exception applies to metal removal performed by the Repair/Replacement Organization as part of a
repair/replacement activity, including fabrication of parts, installation of replacement items, modification of items, and defect
removal. The requirements of IWA-4460 are discussed in
Section 27.10.6. It is important to note that this exception
addresses the process of metal removal and does not eliminate the
examinations required by the Construction Code following metal
removal. (Note, however, that if metal removal is used for removing a defect, the second exception discussed in the following
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manufacture the valve. When the valve is replaced, the
Construction Code used to manufacture the original valve will be
used to obtain the replacement valve, and the installation
Construction Code used to install the original valve will be used
to install the replacement valve. For the installation of a new item
into an existing system (i.e., there is no similar existing item
being replaced), IWA-4421(a) in the 1997 Addenda through the
2000 Addenda allows the Construction Code used for the installation of the new item to be the same Code used for the installation
of the system that contains the new item. No such provision was
included in the 2001 Edition changes to IWA4400, but this was
not a deliberate change, and the intent would be to continue to use
the earlier guidance when installing a new item not previously
existing in the system.
IWA-4421(b) in the 1997 Addenda through the 2000 Addenda
provides an alternative to the original Construction Code for
welding, brazing, defect removal, fabrication, and installation
activities. The 2001 Edition and later editions and addenda have
similar provisions in IWA-4411 and IWA-4411(a) and (b) except
that IWA-4411 does not invoke the Construction Code for defect
removal requirements. Both the earlier 1997 Addenda and the
subsequent 2001 Edition changes, including later editions and
addenda, allow use of a later edition or addenda of the
Construction Code or a later different Construction Code, either
in its entirety or portions “thereof”. A portion of a selected alternative Construction Code may be used in lieu of or in addition to
the requirements of the original Construction Code, provided all
related requirements are met and a complete and consistent set of
Code requirements is used (i.e., the portion of the selected alternative Construction Code combined with the remaining portion
of the original Construction Code provides a complete and consistent set of Code requirements). Caution must be applied when
using portions of a Code. Inexperienced users might not recognize the related requirements in the alternative Construction
Code that must be used with the portion of the alternative
Construction Code selected for use. These paragraphs also allow
Code Cases to be used that were not used with the original
Construction Code. When different Construction Codes are used,
the substitution must be in accordance with IWA-4221(c). It
should be noted that the 1997 through the 1999 Addenda incorrectly reference IWA-4221(b) instead of the correct reference,
which is IWA-4221 (c).
IWA-4421(b) in the 1997 Addenda through the 2000 Addenda
and IWA-4411(a) in the 2001 Edition and later editions and
addenda both require that filler material requirements must be reconciled in accordance with IWA-4224. But no other reconciliation
is required when one uses a later edition and addenda of the
Construction Code, or later different Construction Codes, or Code
Cases for welding, brazing, fabrication, or installation. However,
the reconciliation requirements of IWA-4220 are required to be
met for items being installed or modified. It must also be noted
that if the use of a later or different Construction Code results in
any change in design or configuration of an item or system, the
change must be evaluated in accordance with IWA-4311. (Many
Owners’ programs would classify a change in Code edition and
addenda as a design or configuration change.) Use of a later
Construction Code or a different Construction Code for fabrication of a component, installation of a piping system, or modification of a component or piping system, will usually require an
update to the applicable Stress Report or Design Report because
the original Construction Code no longer provides the basis for
Code compliance.
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E
XI-1-95-29:
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Question (1): Are the requirements of IWA-4300, for defect
removal and examination of the removal cavity, in the 1988
Addenda through the 1990 Addenda, applicable to repair
activities performed in accordance with the Construction
Code or Section III, when the alternative weld repair methods
of IWA-4500 or IWB-4000/IWC-4000/IWD-4000/IWE-4000
(e.g., half bead or temper bead welding) are not used as an
alternative to the Construction Code or Section III requirements imposed by IWA-4120?
Reply (1): No.
Question (2): Are the requirements of IWA-4300, for defect
removal and examination of the removal cavity, in the 1991
Addenda through the 1995 Edition, applicable to repair
activities performed in accordance with the Construction
Code or Section III, when the alternative weld repair methods
of IWA-4400 or IWA-4500 (e.g., temper bead welding) are not
used as an alternative to the Construction Code or Section III
requirements imposed by IWA-4170(b)?
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Before discussing the more recent IWA-4400 requirements on
defect removal, the history of several Code changes needs to be discussed. This discussion is important for users working to Section
XI editions and addenda earlier than the 1996 Addenda and it gives
a background for understanding the later Code changes.
Historically, confusion over the applicability of Section XI
defect removal requirements was common for both users and
Code Committee personnel. This confusion was compounded by
changes in the 1988 Addenda of Section XI, in which much of the
repair requirements of IWA/B/C/D/E-4000 were consolidated in
IWA-4000, and in the 1991 Addenda, which combined the repair
and replacement requirements into IWA-4000. Both addenda
incorrectly stated the applicability of the defect removal requirements; those requirements that originally had been intended for
use only with special alternative welding methods, such as half
bead welding, were incorrectly applied to all defect removal
activities. The rewrite of IWA-4000, published in the Addenda,
editorially reorganized the requirements into functional areas by
using the requirements as they existed in the 1995 Edition; thus
defect removal requirements included in IWA-4400 also incorrectly applied the requirements to all repair/replacement activities.
After the approval of the 1995 Addenda content, Subcommittee
XI reconsidered the applicability of the defect removal requirements to all repair/replacement activities. Research of the original
requirements and subsequent Code changes were persuasive in
concluding that the original defect removal requirements were
intended for use only with the special Section XI alternative welding methods, such as half bead welding. An errata to the earlier
IWA-4000 requirements was approved, which corrected the
applicability of the defect removal requirements, but unfortunately,
the errata was not approved in time to go into the 1995
Addenda rewrite and therefore was published in the 1996
Addenda. The 1996 Addenda relocated IWA-4420 (defect
removal requirements) to a new IWA-4611, which applied the
defect removal requirements only to the alternative welding
methods in IWA-4600.
Because of the confusion on this subject in the industry,
Subcommittee XI considered and approved two interpretations to
clarify the requirements. These two interpretations address the
applicable editions and addenda of Section XI from the Summer
1974 Addenda through the 1995 Edition.
XI-1-95-25 (applicability with Summer 1974 Addenda through
1987 Addenda):
Reply: No.
AS
27.10.3 Defect Removal
Question: Are the requirements of IWB-4000 for defect
removal and examination of the removal cavity applicable to
repair activities performed in accordance with the
Construction Code or Section III, when the alternative weld
repair methods of IWB-4000/IWC-4000/IWD-4000/IWE4000 (e.g., half bead welding) are not used as an alternative
to the Construction Code or Section III requirements imposed
by IWA-4120?
Y
paragraph will require the examinations of IWA-4422 in lieu of
the Construction Code examinations.)
The second exception to the Construction Code addresses the
removal of defects in material or previously accepted welds. Inprocess weld defects found during the welding process and before
the final weld acceptance are not included in this exception
(i.e., in-process weld defects are corrected in accordance with the
Construction Code requirements used to perform the welding).
This second exception states that the requirements of IWA-4422
are to be used in lieu of Construction Code requirements for
examination of defect removal areas. IWA-4422 was added in the
1997 Addenda to consolidate NDE requirements to reduce unnecessary Construction Code referencing and to simplify NDE
requirement (because Construction Code NDE requirements vary
widely based on the product form being repaired). IWA-4422 also
requires some additional NDE when the Construction Code does
not require NDE following defect removal.
Reply (2): No.
The errata and interpretations make it clear that the IWA-4000
defect removal requirements did not apply to Section XI repairs
made in accordance with the Construction Code. However, the
requirements that did apply were not very clear. Many committee
personnel and users felt it necessary to clarify the applicability of
the Construction Code for performing repair/replacement activities, as well as clarify nondestructive examination requirements
associated with defect removal operations. Therefore, a revision
to IWA-4400 and IWA-4600 was expeditiously prepared and
approved and was published in the 1997 Addenda. The change in
the 1997 Addenda was considered Phase 1 of a two-part revision
and clarification of the requirements in IWA-4400 and IWA-4600.
Additional changes to IWA-4400, IWA-4500, and IWA-4600
were made in the 2001 Edition as part of Phase 2, which revised
the paragraph numbering and rearranged the requirements one
more time to further clarify the requirements in IWA-4400 and
IWA-4600.
It is hoped that the explanation presented in the preceding several paragraphs is helpful to the user who observes the numerous
changes to defect removal requirements in IWA-4400. It is unfortunate that these Code changes weren’t better coordinated.
One other related change needs to be discussed before the
review of the more recent requirements. Before the 1999
Addenda, IWA-4000 inconsistently used the terms flaw removal,
defect removal, and metal removal, which led to differing opinions about what constituted a repair/replacement activity—even
among the Section XI Code Committee personnel. After considerable discussion and review of the history of IWA-4000 revisions,
Subcommittee XI concluded that the appropriate interpretation of
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Question: When a flaw meeting the acceptance criteria of
Section XI (i.e., not a defect) is corrected by mechanical metal
removal only (no subsequent welding, brazing, or replacement activities), must the work be performed in accordance
with the provisions of IWA-4000?
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Question: Can internal wall thinning be repaired by external
welding in accordance with Section XI, IWX-3100 without
defect removal in accordance with IWA-4300 (IWX-4300 in
Edition and Addenda prior to the 1991 Addenda)?
Reply: Yes.
Y
IWA-4422.1 does not require that welding be performed after
defect removal or partial removal. It allows the cavity created by
the removal process to remain if the section thickness at the base
of the cavity is at least the minimum thickness required by the
Construction Code. The metal removal process is required to meet
IWA-4460 that has requirements for the area to be faired into the
surrounding area in accordance with the Construction Code provisions. If the section thickness at the base of the cavity is less than
the required minimum thickness, additional repair/replacement
activities, such as welding or replacing the item, are required.
Rather than performing these additional repair/replacement activities, IWA-4422.1 (b) notes that the defect removal area and any
remaining portion of the defect may be evaluated and the component accepted if the Section XI flaw evaluation provisions are met
or additional design evaluations are performed in accordance with
IWA-4311 to show acceptability.
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Reply: No. However, if the metal removal activity affects a
previous preservice or inservice examination record, a new
preservice examination in accordance with Section XI shall
be performed and documented following the completion of
the mechanical metal removal activity.
does not require a defect to be removed. It states that “A defect is
considered removed when it has been reduced to an acceptable
size.” This wording was carefully chosen to allow a defect to
be removed, to allow a defect to be partially removed so that the
remaining flaw is reduced to an acceptable size in accordance with
the acceptance standards of Section XI (IWB/C/D/E/F3000), or to
allow weld buildup material to be added to the thickness of an item
so that a flaw originally classified as a defect is reduced to a size
that meets Section XI acceptance criteria. In this last method of
reducing a defect to an acceptable size, no metal removal is performed. An example of this method is provided in Interpretation
XI-1-92-59, which follows.
AS
these requirements was that metal removal referred to removal of
defects and that removal of flaws was not a repair. This opinion
was supported by two approved B&PV Committee actions that
clarified the requirements, both of which were published in the
1999 Addenda. These actions changed both the terms flaw
removal and metal removal to the one term of defect removal in
all but a few specific locations. One such location was in the provisions of IWA-4460 that were determined to be applicable to all
metal removal associated with a repair/replacement activity and,
therefore, were not changed to defect removal.
There are two interpretations that attempt to clarify the applicability of flaw removal and metal removal activities for users working to
earlier Code editions and addenda. Interpretation XI-1-98-20R,
which follows, is applicable to the 1986 Edition through the 1997
Addenda and notes that flaw removal by mechanical metal removal
is not a repair and does not need to meet IWA-4000.
TA
Interpretation XI-1-98-08, which follows, notes that metal
removal for maintenance reasons is not a repair unless a defect is
present. It has an applicability of the 1986 Edition through the
1995 Edition.
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Question: Is it a requirement of IWA-4100 that machining of
a pressure boundary component’s sealing surface to remove
pitting or other surface irregularity identified through normal
maintenance be considered a repair activity?
Reply: No, provided the pitting or other surface irregularity
is not a defect.
PR
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Having discussed some of the important changes that clarified
the applicability of the defect removal requirements, the more
recent requirements for defect removal are reviewed and discussed in the following sections 27.10.3.1 and .2. The examination requirements associated with defect removal are discussed in
Section 27.10.4. As noted in section 27.10, section 27.10.3
retained the Companion Guide first edition discussion of the
defect removal requirements contained in IWA-4420 in the 1997
Addenda through the 2000 Addenda. In addition, the second edition was expanded to include discussion of the 2001 Edition
changes through the 2004 Edition requirements. There were no
Code changes through the 2007 Edition that affected the content
of Section 27.10.3.
27.10.3.1 Defect Removal –1997 Addenda Through 2000
Addenda IWA-4422.1 includes the requirements for defect
removal. It requires the defect removal process to be in accordance
with IWA-4421, which determines the applicable Construction
Code to use. It restates the exception that thermal removal processes
are to be in accordance with IWA-4460 in lieu of the Construction
Code, as previously discussed in Section 27.10.2. IWA-4422.1
27.10.3.2 Defect Removal –2001 Edition and Later As noted
in section 27.10.1.2, the 2001 Edition substantially reorganized the
content of IWA-4410 and IWA-4420. A new IWA-4420 was added
and titled Defect Removal Requirements. IWA-4421 was added
containing general requirements for defect removal. It required
that defects shall be removed or mitigated by one of four methods
and included references to the paragraphs that were to be used for
each method. The four methods are: 1) defect removal by mechanical processing (IWA-4462); 2) defect removal by thermal methods (IWA-4461); 3) defect removal or mitigation by welding or
brazing (IWA-4411); and 4) defect removal or mitigation by
modification (IWA-4340).
IWA-4422 was revised from Defect Removal and Examination
to Defect Evaluation and Examination. IWA-4422 is to be used
along with IWA-4421 in all defect removal activities. IWA-4422.1
was revised from Defect Removal to Defect Evaluation because
that title better described its content. A portion of IWA-4422.1
was removed because it implied that all defect removal operations
involve metal removal and creation of a cavity. However, at least
two of the methods listed in the new IWA-4421 do not involve
metal removal or cavity creation, e.g., welding to replace eroded
metal and defect removal by modification.
The reorganization and revisions in the 2001 Edition did not
change the nondestructive examination requirements associated with
defect removal. Therefore, the discussion in section 27.10.4 is
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27.10.5 Welding and Welder Qualification
Requirements
IWA-4440 provides requirements for welding and welder
qualification. IWA-4440(a) requires that welding be performed in
accordance with welding procedure specifications qualified by the
Repair/Replacement Organization in accordance with the
Construction Code identified in the Repair/Replacement Plan.
Similarly, IWA-4440(c) requires that welders be qualified by the
Repair/Replacement Organization in accordance with the
Construction Code identified in the Repair/Replacement Plan.
Previous requirements, IWA-4300 before the 1988 Addenda
and IWA-7320 before the 1991 Addenda, stated that welding and
welders must be qualified in accordance with Section IX and the
additional requirements of Sections III and XI. For older plants,
some of the original Construction Codes did not require
qualification to Section IX (e.g., supports fabricated in accordance
with AWS D1.1). Committee actions determined that the acceptability of the original Construction Code should continue; consequently, Section XI in the 1988 Addenda and the 1991 Addenda
was changed to allow the Construction Code qualification requirements. Owners working to editions and addenda earlier than these
addenda may find the following interpretation—XI-1-98-54—
helpful, for it clarifies this issue. (Interpretation XI-1-89-01 also
addressed this issue, but without as much clarity.)
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IWA-4422.2 has nondestructive examination (NDE) requirements for both defect removal without subsequent welding or
brazing and defect removal followed by welding or brazing.
IWA-4422.2.1 provides the NDE requirements for defect
removal without subsequent welding or brazing. The NDE
method required after defect removal is based on the method that
originally was used to identify the defect unless it is detected
visually, in which case surface examination is required. In all
cases, though, NDE is required after removal activities. IWA4422.2.1(c) allows the acceptance criteria of either the
Construction Code or Section XI to be used in the acceptance of
the NDE results. Because IWA-4422.1 does not require the defect
to be completely removed, IWA-4422.2.1(c) allows the Section
XI fracture-mechanics-based acceptance criteria in the tables of
IWB-3000 and IWC-3000 to be used to accept a partially
removed defect. Doing so may be important for the acceptance of
an item without subsequent welding when the defect is shallow
and the defect removal cavity has been carefully controlled to
ensure that the remaining section thickness is at least the minimum required thickness of the item. If the remaining portion of
the defect is smaller than the Section XI acceptance standards, the
item is acceptable without further removal even if it is not acceptable to the Construction Code acceptance criteria.
IWA-4422.2.2 provides the NDE requirements for defect
removal when followed by welding or brazing. IWA-4422.2.2(a)
requires surface examination of the defect removal area before
welding unless one of three conditions exist. The first condition
that would eliminate the surface examination requirement is when
the excavation removes the full thickness of the weld or base
material. The second condition is when the surface examination
cannot be performed or will not provide meaningful results, in
which case an evaluation in accordance with IWA-4422.1(b) must
establish the acceptability of any remaining portion of the defect.
Alternative NDE methods may be used to characterize any
remaining portion of the defect for use in the evaluation. The following example may help to illustrate how an evaluation can be
used in lieu of performing a surface examination of the defect
removal area: A through-wall leak develops in a pipe from microbiologically induced corrosion, and a subsequent evaluation
shows excess thickness in the pipe beyond minimum required
thickness. In this case, the repair/replacement activity can be
accomplished by excavating from the outside surface of the pipe
to a depth slightly beyond minimum required thickness with the
intent of welding the cavity out to the surface. IWA-4422.2.2(a)
requires a surface examination before welding; however, the presence of the hole at the base of the excavation would render surface NDE results meaningless. Because the evaluation shows that
the minimum required thickness will be provided after welding,
and also because the surface NDE will not provide meaningful
results, the surface NDE is therefore not required.
The third condition of IWA-4422.2.2(a) that would eliminate the
surface examination requirement before welding involves volumetric examination of the area after welding. IWA-4422.2.2(a)(3) does
not require the surface examination if the final volumetric examination will be performed on the completed repair, the final volumetric examination method is the same as the method used to
detect the defect, and the volume to be examined includes the
AS
27.10.4 Nondestructive Examination Associated
With Defect Removal
location of the original defect. Obviously, if the final volumetric
examination shows that the defect was not reduced to an acceptable
size before welding, the volume will need to be excavated again to
remove the defect or otherwise reduce it to an acceptable size.
IWA-4422.2.2(b) has the same provision that was noted in
IWA-4422.2.1, which allows the acceptance criteria of either the
Construction Code or Section XI to be used for acceptance of the
defect removal area. Paragraph (c) clarifies that the surface examination of the defect removal area is not required for brazed joints.
Paragraph (e) notes for clarity that, after welding, the examinations
of IWA-4520 are required to accept the completed weld (i.e., the
requirements of IWA-4422.2.2 do not apply to the completed weld).
Y
equally applicable to the 1997 Addenda and the 2001 Edition,
including later editions and addenda as addressed in this Chapter 27.
Question (1): Is it the intent of IWA-4300 for repair welding to
components and their supports which were originally constructed to welding requirements other than Section IX (e.g.,
AWS D1.1) to be performed with welders and welding procedure specifications qualified in accordance with ASME Section
IX and the additional requirements of Sections III and XI?
Reply (1): No, the welding requirements from the original
Construction Code may be used.
Question (2): Is it the intent of IWA-7320 for replacement welding to components and their supports which were originally
constructed to welding requirements other than Section IX
(e.g., AWS D1.1) to be performed with welders and welding
procedure specifications qualified in accordance with ASME
Section IX and the additional heat treating and impact tests
required by IWB-4000?
Reply (2): No, the welding requirements from the original
Construction Code may be used.
IWA-4440(b) was added in the 1997 Addenda as the incorporation of Code Case N-573. IWA-4440(b) allows an alternative to
Section IX, QW-201 by allowing Owners to use welding procedure
qualifications performed and documented by other Owners.
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performed by the repair organization (when the repair organization is not the Owner)?
Reply (2): No, except when the Owner retains direct supervision of the welders being used to perform the weld repair.
Interpretation XI-1-83-43:
Reply (1): No.
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Question (1): An Owner is acting as a repair organization
using weld procedures which he has qualified and performs
the repair under his direct supervision using welders from
labor Contractor A. If the Owner then changes the labor contractor to Contractor B, but still uses the same welders, is he
required under the rules of Section XI to requalify the
welders?
Y
AS
Question (2): An Owner is using Contractor A as a repair
organization, using Contractor A’s qualified weld procedures
and welders. If the Owner then hires Contractor B to replace
Contractor A as the repair organization, with Contractor B
retaining the same repair supervision and welders as those
used by Contractor A, must the weld procedures and welders
be requalified?
Reply (2): Yes.
Simultaneous qualification of welding procedures and welders
by more than one organization has been an area of interest. The
following two interpretations address this subject.
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However, the provisions do not apply to Repair/Replacement
Organizations other than Owners. There may be consideration in
the future to expand these provisions to other Repair/Replacement
Organizations. Repair/Replacement Organizations, other than
Owners, were excluded initially because of concerns over how to
adequately control these provisions. Owners working to Section XI
editions and addenda earlier than the 1997 Addenda should consider
use of Code Case N-573 so that they may use these provisions.
IWA-4440(b) was revised in the 2006 Addenda as part of a
broader Boiler and Pressure Vessel Committee action. That action
was to clarify that records of welder and welding operators shall
be maintained in accordance with Section IX and the applicable
Code governing the work, e.g., Section XI for repair/replacement
activities, but may use methods other than written signatures for
certification of the qualification records. The IWA-4440(b) revision eliminated wording that implied signing or certifying in writing, but did not change the intent of the paragraph. A related
change requiring such provisions to be included in the Owner’s
QA Program was not added until the 2007 Edition (see Section
27.5.2 for discussion of that change).
IWA-4440(c) requires all welders to be qualified by the
Repair/Replacement Organization in accordance with the Codes
specified in the Repair/Replacement Plan. Code Case N-600
allows Owners an alternative for welder, welding operator, brazer,
and brazing operator performance qualification. Case N-600 permits an Owner to accept performance qualifications from other
Owners. Transfer of Performance Qualification Records was permitted by both ASME B31.1 and ASME B31.3, and this Case
incorporates the methodology from these Codes. The Case provides restrictions applicable to the performance qualification
activity as well as to the administration, transfer, and receipt of
Performance Qualification documentation and provides effective
quality control without unnecessary costs.
IWA-4440(d) provides requirements for use of contract welders.
Because these requirements have been in Section XI since the
Summer 1978 Addenda, they are probably familiar to most
Repair/Replacement Organizations. The provisions allow use of
contract welders provided the Repair/Replacement Organization’s
QA Program controls the use of such welders. The QA Program
needs to include requirements for complete and exclusive administration and technical supervision of the welders by the
Repair/Replacement Organization, and requirements for contractual
control that provide authority to assign and remove welders at the
discretion of the Repair/Replacement Organization. The description
of these controls in the QA Program must be acceptable to the ANII.
There are several Section XI interpretations regarding the
qualification of welding procedures and welders, some of which
are included here to assist in the understanding and use of the
requirements. The following two address the use of contract
welders. (These provisions were originally in IWA-4300.)
Interpretation XI-1-83-81:
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Interpretation XI-1-92-08:
Question (1): Is it a requirement of IWA-4300(c)(1), Section
XI, Division 1, 1983 Edition through the Winter 1984
Addenda, that the complete and exclusive administration and
technical supervision of all welders by the repair organization include the supervision of the welders during Welder
Performance Qualification testing under Section IX?
Reply (1): Yes.
Question (2): In accordance with IWA-4300, may welding
procedures qualified by the Owner be used on work
Question: In accordance with Section XI, IWA-4300, can several repair organizations simultaneously supervise the welding of a single procedure qualification test coupon and each
use the resulting procedure qualification record (PQR) to
generate their own welding procedure specifications?
Reply: Yes.
Interpretation XI-1-89-35:
Question (1): In accordance with Section XI, IWA-4330, can
several contractors or assemblers simultaneously conduct the
performance qualification test(s) of a welder?
Reply (1): Yes.
Question (2): In accordance with Section XI, IWA-4330, can
a welder simultaneously weld performance qualification test
coupons in accordance with a welding procedure
specification of several contractors or assemblers when the
essential variables are documented as identical?
Reply (2): Yes.
Sometimes a Construction Code or Section XI may impose
requirements in addition to Section IX requirements. For example, Section IX allows the use of a welding procedure
specification (WPS) to continue without the need to requalify it to
include any variables required by later Section IX editions and
addenda; but if a change in a WPS requires requalification, the
procedure qualification is required to be performed in accordance
with the current Section IX requirements. However, if a
Construction Code or Section XI imposes qualification requirements in addition to the Section IX requirements, those additional
requirements must be met. If those additional requirements are
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revised because of an update of the Section XI edition and addenda, the qualification must be updated to meet the currently applicable Section XI requirements. This matter has been clarified by
Interpretation XI-1-83-41R, which follows.
Question: Is it the intent of Section XI that electric discharge
machining (EDM) and metal disintegration machining
(MDM) processes be considered thermal metal removal
processes?
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27.10.6 Special Requirements for Thermal Removal
Processes
Y
Before this discussion of welding and welder qualifications is
finished, one additional clarification should be noted. IWA-4440
is one location where brazing should also be included, as noted
previously in the discussion on brazing in Section 27.10.
Therefore, as used in IWA-4440, welding and welders should
equally be read to include brazing and brazers.
For additional information on welding and brazing, refer to
Chapter 24 of this book, which discusses Section IX welding and
brazing requirements.
AS
Reply: No. The provisions of the Edition of the Code being
used for the ISI Program (IWA-2410) must be met.
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Question: If welding procedures are qualified in accordance
with the repair sections of Section XI (specifically IWB-4400)
but prior to the current Edition, are the procedures still valid
for use if essential variables or qualification test requirements
have changed?
Although thermal metal removal requirements have been
included in IWA-4000 as part of the defect removal requirements
since the Summer 1978 Addenda, Section XI did not define what
processes were considered thermal processes. However, IWA4461, added in the 1997 Addenda, did provide a list of processes
that were considered thermal processes. Included in this list of
processes are oxyacetylene cutting, carbon arc gouging, plasma
cutting, metal disintegration machining (MDM), and electrodischarge machining (EDM). Although the thermal process
classification for the first three processes would be expected, it
might not be expected for the last two thermal processes. A technical evaluation of some MDM and EDM processes was performed by the Working Group on Welding and Special Repair
Processes (one of the Working Groups under the Section XI
Subgroup on Repairs, Replacements, and Modifications) that
showed that MDM and EDM can be similar to thermal removal
processes. Both MDM and EDM have become popular metal
removal processes for plant modifications and work on existing
plant items for such reasons as excellent cutting control and minimal debris created during the metal removal process.
Interpretation XI-1-95-60, which follows, clarifies the
classification of MDM and EDM as thermal processes. The
applicability of this interpretation is the 1989 Edition through the
1997 Addenda.
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IWA-4460 provides requirements for metal removal. IWA-4460
was added to IWA-4400 in the 1997 Addenda in a manner that
would make it applicable to all activities covered by IWA-4400
and IWA-4600. Metal removal requirements existed in IWA-4000
before the 1997 Addenda, but were only part of defect removal
requirements, as discussed in Section 27.10.3. Clarification that
the IWA-4460 requirements were not limited to defect removal
can be seen in the 1999 Addenda and 2001 Edition changes. An
action included in the 1999 Addenda changed the term “metal
removal” to “defect removal” in each location where metal
removal was determined to be an incorrect expansion of the original intent of Section XI. Committee action to make these terminology changes specifically determined that IWA-4460 should
retain the term metal removal because it should cover additional
activities beyond defect removal. This was further clarified by the
2001 Edition changes to the IWA-4400 title, changes to IWA4410, the specific addition of IWA-4413, and the changes to
IWA-4462 to make mechanical removal requirements only applicable to defect removal.
After the 2001 Edition change, IWA-4460 includes requirements for thermal metal removal and mechanical defect removal.
Although minimal requirements are included in IWA-4462 for
mechanical defect removal, numerous requirements are included
in IWA-4461 for thermal metal removal. The thermal metal
removal requirements are similar to the requirements associated
with defect removal that have existed since the Winter 1985
Addenda. However, in addition to applying to all metal removal
activities, IWA-4461 also differs from the previous requirements
by adding three new provisions. The first is a listing of what
processes are considered to be thermal removal processes; the
second shows that the requirements for P-No. 1 materials were
changed (for the P-number classification system, see Section IX,
QW-420); and the third shows that provisions were added to
allow alternatives to the requirement for mechanical processing of
thermally cut surfaces. Each of these provisions is discussed in
the following paragraphs.
Reply: Yes. Specific requirements will appear in the 1996 and
1997 Addenda.
IWA-4461.1 provides the requirements for thermal metal
removal on P-No. 1 materials (carbon steel). It was revised in
the 1997 Addenda to require only that surface oxides be
removed by mechanical processing before welding on cut surfaces. However, the 1997 Addenda failed to make the related
change to Table IWA-4461.1-1. The 2001 Edition corrected this
error by deleting preheat requirements for P-No.1 material.
IWA-4461.2 provides requirements for many ferritic materials
other than P-No. 1 materials. When preheat in accordance with
the requirements of Table IWA-4461.1-1 is not applied, mechanical processing is required to remove either 321 in. of material
when subsequent welding is to be performed, or 161 in. of material when welding will not be performed. If preheat is applied
before cutting in accordance with Table IWA-4461.1-1, then
material is only required to be removed to bright metal by a
mechanical method. IWA-4461.3 provides requirements for
P-No. 8 and P-No. 43 materials (austenitic and nonferrous materials) and requires that 161 in. of material be mechanically removed
from thermally cut surfaces regardless of whether welding is to be
performed.
IWA-4461.4 was added in the 1997 Addenda to provide an
alternative to mechanically removing additional materials from
thermally cut surfaces, as required by IWA-4461.2 and IWA4461.3. It provides for qualification testing to show that the thermal removal process is acceptable in the as left surface condition
and identifies a number of tests and inspections to be performed
as part of the qualification process. When a P-No. material has
been qualified at the maximum heat input to be used in production, additional qualifications are not required. This alternative
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1988 Addenda, IWA-4600 in the 1988 Addenda through the 1990
Addenda, and IWA-4800 in the 1991 Addenda through the 1993
Addenda) required only a preservice examination and the repetition
of the examination that detected the flaw. The examinations of the
Construction Code were invoked by the other general provisions in
IWA-4000 that require welding and brazing to be done in accordance with the Construction Code. This was clarified by
Interpretations XI-78-13, XI-81-07, and XI-1-86-51. Interpretation
XI-1-86-51, which best clarifies the requirement, follows.
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Question: Following installation of a replacement component
or piping assembly by welding in accordance with IWA-4600,
are the NDE examination requirements specified for installation welds in the original Construction Code required to be
met in addition to those specified in IWA-4500 and IWA-7530?
AS
Reply: Yes; however, when an examination requirement is
impossible or impractical to perform, an alternate examination may be used provided it is documented in the Repair
Program, which is subject to review by the enforcement and
regulatory authority having jurisdiction at the plant site.
Y
As discussed in Section 27.6.1, the provisions in the reply of
this interpretation regarding the use of alternatives when documented in the Repair Program should not be used without consideration of regulatory and enforcement authority requirements.
The revision to IWA-4800 in the 1994 Addenda was a
clarification of requirements consistent with these previous interpretations. In the revision, IWA-4800 was divided into IWA-4810,
addressing examinations to determine the acceptability of the
repair or replacement, and IWA-4820, addressing performance of
preservice examinations to establish a new baseline for future
inservice inspections. This separation of examination requirements from preservice examination requirements was continued
in the rewrite of IWA-4000 in the 1995 Addenda and is reflected
in the current IWA-4500 provisions.
IWA-4520(a) in the 2007 Edition requires that welding and
brazing be examined in accordance with the Construction Code
identified in the Repair/Replacement Plan with two exceptions
that were added in the 2001 Edition. Clarification regarding
examination associated with fabrication by a Repair/Replacement
Organization was added to IWA-4520(a) in the 2005 Addenda
(see Section 27.5.3 for additional information). IWA-4520(b)
allows these examinations to be performed concurrently with the
preservice examinations required by IWA-4530. In some cases,
such as a surface examination, this allows one examination to be
performed to meet the requirements of both the Construction
Code examination and the Section XI preservice examination.
Care should be taken when crediting both requirements to ensure
the examination encompasses all the requirements of both Codes.
In the example of the surface examination, the required area of
coverage is slightly different between Section III and Section XI,
which necessitates the use of the more stringent requirements that
envelop both sets of requirements to credit both examinations
with one concurrent examination.
When Section XI requires the examinations to be in accordance
with the Construction Code, alternatives allowed by the
Construction Code may also be used. For example, the 2005
Addenda change in Article 2 of Section V of the Boiler and
Pressure Vessel Code incorporates Code Case 2476 and allows
the use of radiography using phosphor imaging plates. When the
Construction Code wording does not limit radiography to film
radiography, use of the later Section V, Article 2 provisions can be
EXAMINATION AND TESTING
REQUIREMENTS
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27.11
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was intended to be particularly useful for MDM and EDM
processes.
IWA-4461.4 was revised in the 2001 Edition to add a second
alternative to mechanical processing after thermal metal removal.
The existing qualification alternative was renumbered as IWA4461.4.1. The new alternative was added as IWA-4461.4.2,
Evaluation of Thermally Cut Surfaces. IWA-4461.4.2 describes
the evaluation process whereby thermal metal removal is permitted without subsequent mechanical processing. This alternative
enables as Owner to perform a documented evaluation to determine whether elimination of mechanical processing is acceptable.
For example, in a high radiation area, carbon arc-gouging may be
used to cut off a section of an ASME hanger to eliminate an interference. The cut end is not load bearing and will not result in the
as-cut surface being of being of concern. In this example, IWA4461.4.2 would permit the Owner to leave the cut surface as-is,
providing an alternative to either mechanical processing or
qualification of the thermal removal process.
Unfortunately, for Owners in the United States, the provisions
of IWA-4461.4.2 have been prohibited by a limitation in Federal
Regulation 10CFR50.55a(b)(2)(xxiii), effective November 1, 2004.
The limitation states “the use of the provisions for eliminating
mechanical processing of thermally cut surfaces in IWA-4461.4.2
of Section XI, 2001 Edition through latest edition and addenda
incorporated by reference in paragraph (b)(2) of this section are
prohibited.” [12] The supplemental information in the Federal
Register publication of this final rule, effective November 1,
2004, states that “the NRC believes that it is impracticable to justify the elimination of mechanical processing of a thermally cut
surface in an evaluation as specified in IWA-4461.4.2. It is not
possible to evaluate the adverse effects that can occur as a result
of thermal cutting without performing appropriate tests, inspections, and analyses.” [12]
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IWA-4500 provides requirements for examinations and tests to
be performed as part of the repair/replacement activity. It addresses examinations required as part of welding or brazing activities
performed in accordance with the referenced Construction Code
requirements, the Section XI preservice examinations required
before the item is returned to service, and the Section XI pressure
tests to be performed in lieu of the Construction Code pressure
tests. Each of these areas is covered in the following paragraphs.
Prior to the 2003 Addenda, IWA-4510 “General Requirements”
only noted that the requirements were in the course of preparation. IWA-4511 was added in the 2003 Addenda and modified in
the 2004 Edition to permit IWA-2300 requirements for personnel
qualifications to be used in lieu of the Construction Code personnel qualification requirements for repair/replacement activities.
This change permits an Owner to maintain examination personnel
qualification to CP-189 for ISI and repair/replacement requirements rather than meet qualification requirements from multiple
sources.
27.11.1 Examinations
Examination requirements for the repair and installation of items
were not clearly stated in Section XI until a revision to IWA-4800
in the 1994 Addenda. Before the revision, the paragraph in IWA4000 specifically addressing examination (IWA-4500 before the
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editions of those standards for performing repair/replacement
activities and required Section XI preservice examinations. For
both Owners and vendors, there would appear to be a reasonable
saving of both time and resources if there were only one personnel
qualification standard for use in both repair/replacement activities
and inservice examinations. This was considered by Subcommittee
XI and, as noted in Section 27.11, was included in the 2003
Addenda in IWA-4511 and revised in the 2004 Edition. Until use
of these later provisions, Repair/Replacement Organizations must
ensure that their NDE personnel qualification program encompasses
all of the personnel qualification requirements of each
Construction Code used and each of the personnel qualification
requirements of Section XI used for preservice examinations.
The acceptance criteria of the Construction Code must be used
when performing examinations required by the Construction
Code. Interpretation XI-1-92-35R, which follows, addresses the
question of whether the acceptance standards of Section XI can
be used in lieu of the acceptance criteria of the Construction
Code. The response indicates that Section XI acceptance standards cannot be used.
Y
Question (1): When performing repairs by welding on pressure boundary materials in accordance with Section XI, may
the acceptance standards for flaws found during the inspection of the repair weld be accepted per IWB-3000/IWC3000/IWD-3000/IWF-3000 in lieu of the Construction Code
acceptance criteria with justification?
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used allowing phosphor imaging plate radiography in complete
compliance with the Construction Code and thereby with Section
XI. Changes to Construction Code provisions to allow phosphor
imaging plate radiography may not be obvious. As an example,
although not applicable to repair/replacement activities, Section
XI revised IWA-2231 in the 2005 Addenda to omit film radiography wording when requiring radiography in accordance with
Section V, Article 2, thereby allowing ISI radiography to be performed using any radiography techniques allowed by Section V,
including phosphor imaging plates in accordance with the new
provisions in Section V, Article 2.
Although IWA-4520(a) prior to the 2001 Edition did not include
any exceptions, as we shall see later in Section 27.12, the provisions for alternative welding methods of IWA-4600 do not use the
Construction Code examinations. Therefore, when using an edition
or addenda earlier than the 2001 Edition, it should be understood
that the requirements of IWA-4520(a) are not to be used when the
alternative welding methods of IWA-4600 are used.
The 2001 Edition added two exceptions to the IWA-4520(a)
requirement that welding and brazing be examined in accordance
with the Construction Code identified in the Repair/Replacement
Plan. IWA-4520(a)(1) exempts Class 3 base material repairs from
volumetric examination when full penetration butt welds in the
same location do not require volumetric examination. This Section
XI exemption eliminates the ASME BPVC Section III ND-2500
requirement to radiograph many Class 3 base metal repairs deeper
than 3/8” or 10% of the section thickness when adjacent butt welds
do not require volumetric examination. IWA-4520(a)(2) specifies
the examination requirements of IWA-4600 and IWA-4700 be
applied in lieu of the examinations required by the Construction
Code when welding is performed in accordance with IWA-4600 or
welding or brazing is performed in accordance with IWA-4700.
The exemption in IWA-4520(a)(2) is a clarification rather than a
new provision. As noted in the previous paragraph, this has been
the intended provision even before it was specifically added in the
2001 Edition. As an additional clarification, IWA-4600 or IWA4700 may require that some examinations or examination acceptance criteria be in accordance with the Construction Code, but
such requirements are limited and used where appropriate rather
than the broad application of Construction Code examination
requirements imposed by IWA-4520(a).
One other subject should be noted regarding performance of
the examinations required by IWA-4520(a). Prior to the 2003
Addenda, NDE personnel qualifications for performing examinations required by IWA-4520(a) are to be in accordance with the
Construction Code used for the examinations. Interpretation
XI-183-40R, which follows, clarifies this subject, and is applicable up through the 2002 Addenda.
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Reply (1): No.
Question: Are NDE personnel performing examinations following IWA-4120 repair or IWA-7210 replacement, and who
have not performed the examination in accordance with Table
IWB-2500-1/Table IWC-2500-1/Table IWD-2500-1, required
to be qualified and certified to the requirements of IWA-2300?
Reply: No. NDE personnel used to perform examinations following a repair or replacement must be qualified and certified
in accordance with the Code used (reference IWA-4120 or
IWA-7120) for the repair or replacement.
It is likely that Repair/Replacement Organizations, including
both Owners and vendors, may need to maintain compliance with
more than one personnel qualification standard and with multiple
Question (2): When applying a stellite hardfacing to a valve
disk and seat, may the acceptance standards of
IWB/IWC/IWD-3000 be used for acceptance in lieu of the
Construction Code acceptance criteria with justification?
Reply (2): No.
IWA-4520(c), added in the 1997 Addenda and subsequently
deleted in the 2005 Addenda, was associated with the action to add
defect removal requirements. The addition of IWA-4520(c),
although initiated by the defect removal action, was determined to
be appropriate for all repair/replacement activities, not just for
those associated with defect removal. IWA-4520(c) allowed the
use of alternative methods of examination, a combination of methods, or newly developed techniques to be substituted for the methods specified in the Construction Code or in IWA-4000, provided
the ANII is satisfied that the results are demonstrated to be equivalent or superior to those of the specified method. This was a technical change not previously allowed in Section XI. Although IWA2240 had similar provisions for Section XI examinations since the
first edition of Section XI, it did not allow the alternatives for
Construction Code-required examinations until the 1998 Edition.
Code Case N-587, “Alternative NDE Examination Requirements
for Repair/ Replacement Activities, Section XI, Division 1,” was
approved to allow early implementation of these alternative examination provisions. The provisions of IWA-4520(c) or Code Case
N-587 were intended to allow such substitutions as an ultrasonic
examination for a radiographic examination.
Unfortunately, for Owners in the United States, the provisions
of IWA-4520(c) were prohibited by a limitation in Federal
Regulation 10CFR50.55a(b)(2)(xix), effective October 26, 2002.
The limitation states “the provisions for the substitution of alternative examination methods, a combination of methods, or newly
developed techniques in the 1997 Addenda of IWA-2240 must be
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Reply: Yes, Section XI, IWF-2200(b) only applies to the initial preservice examination. Subsequent repairs or replacements shall be examined prior to returning the system to service in accordance with IWF-2200(a).
The second interpretation addresses Class 2 preservice inspections following repair/replacement activities. According to IWC2200, preservice inspections on Class 2 items are required to be
performed only on those items selected for examination in the
preservice/inservice inspection programs. Because some categories in Table IWC-2500-1 do not inspect 100% of the welds, a
sample of the welds is selected for examination. This differs from
the preservice requirements for Class 1, where preservice inspections are required for all nonexempt items. For many years, IWA4000 required that preservice examinations be performed after
repairs. It wasn’t until the 1994 Addenda that IWA-4000 preservice inspection requirements were revised to clearly specify that
preservice inspections were to be performed in accordance with
the referenced subarticles for each Code Class. However, when
considering an inquiry on the pre-1994 requirements,
Subcommittee XI determined that the IWA-4000 requirement to
do a preservice examination was always dependent on the actual
preservice inspection requirements in IWB/C/D/E/F/L-2000.
Based on this determination, Interpretation XI-1-98-42, which
follows, clarifies that preservice examinations are not required for
a Class 2 weld if the weld is not selected for inservice inspection.
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To determine if a flaw found during a Section XI inservice
inspection was service induced, Section XI requires preservice
inspections to be performed before placing items in service.
These preservice inspections are examinations that provide a
baseline to compare with the results of subsequent examinations.
Section XI requires that a complete preservice inspection program
be completed before placing a plant in initial service. To maintain
this baseline, any repair/replacement activities that affect previous
preservice or inservice inspections are required to include performance of a preservice inspection. Similarly, new items being
installed, including welded joints installing items, require establishing a baseline for future inservice inspections when required
by IWB/C/D/E/F/L-2200. A repair/replacement activity is not
complete nor can the item be returned to service until the required
preservice inspections are completed.
IWA-4530(a) does not specifically identify the required preservice inspections, but rather references the subarticles in Section XI
(IWB/C/D/E/F/L-2200) that detail the required preservice inspections. Contained in these referenced subarticles are preservice
inspection requirements that the Owner or the Repair/
Replacement Organization must meet to comply with repair/
replacement activity requirements. Users are advised to review
interpretations regarding these referenced subarticles, as well as
review Chapter 28 of this book for additional information.
However, because of the repair/replacement activity requirement to perform preservice inspections, some interpretations have
been issued to clarify the IWA-4000 requirements. One such
interpretation, XI-1-89-42, which clarifies the timing of preservice inspections and Section XI pressure tests, follows.
Question: Is it the intent of Section XI, IWF-2200 to examine
replaced or repaired supports prior to the system being
returned to service?
AS
27.11.2 Preservice Inspection
Two other interpretations regarding performing preservice
inspections after repair/replacement activities are noted here. The
first interpretation, XI-1-89-44, addresses performing preservice
inspections of supports. IWF-2200(b), before the 1991 Addenda,
required that the preservice inspection be performed after hot functional testing, which led to questions regarding whether a support
could be returned to service (i.e., declared operable) until after
heat-up of the system, similar to that performed during hot functional testing. In this interpretation, which follows, it was clarified
that IWF-2200(b) does not apply to repair and replacement performed after the initial preservice inspection performed during hot
functional testing associated with preoperational testing.
Y
applied. The provisions in IWA-2240, 1998 Edition through the
latest edition and addenda incorporated by reference in paragraph
(b)(2) of this section, are not approved for use. The provisions in
IWA-4520(c), 1997 Addenda through the latest edition and
addenda incorporated by reference in paragraph (b)(2) of this section, allowing the substitution of alternative examination methods,
a combination of methods, or newly developed techniques for the
methods specified in the Construction Code are not approved for
use.” [14] The supplemented information in the Federal Register
publication of this final rule noted that the NRC found that there
was a lack of guidance in the Code to ensure proper consideration
of factors when substituting alternative examination for the examinations specified in the Construction Code. For similar reasons,
the NRC is not approving the use of Code Case N-587.
Given the NRC’s prohibition on use of IWA-4520(c) and the
difficulty involved in resolving the NRC’s concerns, the 2005
Addenda of Section XI deleted IWA-4520(c) (and revised IWA2240).
Question: Is it a requirement of Section XI, IWC-2200 that
preservice volumetric and surface examinations of Class 2
vessels (which are being replaced in accordance with IWC7000) be performed following the system pressure test of
IWA-5214?
Reply: No.
This interpretation was incorporated in IWA-4800 in the 1994
Addenda, and is currently located in IWA-4530(a). The current
provision states that the preservice inspections may be performed either before or following the pressure test required by
IWA-4540.
Question: In accordance with IWA-4600(a) and IWC-2200, is
it required to perform a preservice inspection on a repaired
Class 2 weld if the weld has not been selected for inservice
inspection?
Reply: No.
While IWA-4530(a) addresses preservice inspection requirements, the remainder of IWA-4530 addresses preservice testing
requirements. In the 1999 Addenda, these inservice testing
requirements interface with the ASME OM Code[18] for inservice testing of pumps, valves, and snubbers. If a repair/replacement activity is performed that affects a pump or valve performance parameter, or if a repair/replacement activity is performed
on a snubber, the OM Code testing requirements must be met to
ensure that the pump, valve, or snubber is in operational readiness
condition.
The IWA-4530 testing requirements were changed in the 2000
Addenda when Subsections IWP and IWV on pump and valve
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requirements. Interpretation XI-1-83-66, which follows, makes
this fact clear.
Question: When performing repairs and installation of
replacements under the 1977 Edition of Section XI, with the
Summer 1978 Addenda and later Editions and Addenda, are
the hydrostatic tests performed (and test pressure used) in
accordance with Section XI or the original Construction
Code?
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Reply: When performing a repair or installing a replacement
under Section XI only, the Section XI hydrostatic tests are
performed. The original Construction Code hydrostatic tests
are not required.
Y
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In addition to IWA-4700, IWA-5214 contained requirements for
pressure testing repairs and replacements. IWA-5214 contained
three paragraphs regarding how to perform the pressure test, which
is discussed in Chapter 28. However, IWA-5214(a) and IWA5214(e) contained additional requirements regarding when to perform pressure tests and what type of tests to perform for repair and
replacement, which is the subject being addressed in this chapter.
IWA-5214(a) required that the hydrostatic test of IWA-4700(a) be
performed before resumption of service, whereas IWA-5214(e)
addressed replacements installed by mechanical connections. The
pressure tests required by IWA-5214(e) were all tests performed at
system operating pressure (i.e., not at an elevated pressure such as
a hydrostatic test). Therefore, the tests merely involved checking
for leaks at these mechanical connections while at operating pressure. The wording in this paragraph was often misunderstood,
which elicited numerous interpretations to clarify its meaning. The
following are six important interpretations that provide a better
understanding of how to use IWA-5214(e).
Interpretation XI-1-86-13R:
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testing were deleted and in the 2006 Addenda when snubber
examination and testing provisions were deleted from Section XI.
These changes were made because the requirements for pump
and valve testing and snubber examination and testing are contained in the ASME OM Code. IWA-4530 no longer contains
requirements for testing of pumps and valves or examination and
testing of snubbers after repair/replacement activities. These
2000 Addenda and 2006 Addenda deletions do not change the
Owner’s responsibility to determine when work may affect a
pump or valve performance parameter and require performance
of a pump or valve preservice test or when work on a snubber
may require performance of snubber examinations or tests. These
changes simply recognize that the requirements are contained in
the OM Code and Section XI should not contain such requirements. For the benefit of users, a footnote was added to IWA4530 in the 2000 Addenda as a reminder to consider the OM
Code testing requirements for pumps and valves. A similar footnote was added to IWA-4132 concurrent with the deletion of OM
testing requirements for relief valves and a similar note was also
added to IWA-4131.2(d).
With the 2006 Addenda removal of snubber examination and
testing, IWA-4530 no longer contained any specific preservice
testing requirements. Therefore, in the 2006 Addenda the title of
IWA-4530 was revised to “Preservice Inspection”, removing testing from the title.
27.11.3 Pressure Testing
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Pressure testing requirements associated with repair/replacement activities have been very confusing, mostly because of a
lack of specificity in earlier Section XI editions and addenda. The
discussion of the Section XI provisions for pressure testing will
be divided into two parts due to the size of the material presented:
Section 27.11.3.1 discusses the pressure testing requirements, and
Section 27.11.3.2 discusses the Section XI exemptions from pressure testing. In each of these sections, discussion of the earlier
pressure testing requirements is provided along with changes in
pressure testing up to the current 2007 Edition.
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27.11.3.1 Pressure Testing Requirements In the 1989
Edition, pressure testing requirements for repair and replacement
were contained in IWA-4700 and IWA-5214. These paragraphs
identified when to perform the pressure test and what type of test
to perform. For the requirements on how to perform the tests,
these paragraphs referred to IWA-5000. Discussion on the Section
XI requirements for how to perform the pressure tests is included
in Chapter 28. Although the IWA-4700 wording discussed only
repair by welding, IWA-4110(b) stated that the rules of IWA-4000
also applied to installation of items to be used for replacement;
therefore, the pressure testing requirements of IWA-4700 apply to
repair by welding and installation of replacement items. This was
made clearer in the 1991 Addenda, when IWA-4000 and IWA7000 were combined and it was stated that IWA-4710 applied to
a welded repair or installation of a replacement by welding.
However, because the requirements of Section XI refer to the
Construction Code for many of the requirements for repair and
replacement, a new user is always faced with determining which
requirements—those of Section XI or those of the Construction
Code—apply to pressure testing. To reach the correct answer, one
must understand that all of IWA-4000 and IWA-7000 apply to
repair or replacement. Because IWA-4700 contains requirements
for welded repair and installation of replacements by welding, it
takes precedence over the Construction Code pressure testing
Question (2): When using Section XI (1977 Edition with
Addenda through Summer 1978, and later Editions and
Addenda through the 1983 Edition), is a system pressure test
(IWA-5000) required whenever the pressure boundary is
opened and closed (e.g., replacing a valve bonnet gasket)?
Reply (2): No. A Section XI pressure test is required only
when the pressure boundary is opened and closed in the
course of a Section XI repair or replacement, with the exception of those items exempt under IWA-4000/7000 (see
Interpretation XI-1-89-08).
Interpretation XI-1-89-37:
Question: Does Section XI, IWA-5214(e) require a system
pressure test following the disassembly and reassembly of
mechanical joints when such is performed in the course of an
ASME Section XI repair or replacement?
Reply: Yes.
Interpretation XI-1-95-52:
Question: Is it a requirement of IWA-5214(e) to perform pressure testing following the replacement of bolting on a Class
1, 2, or 3 mechanical connection with or without the disassembly of the mechanical connection?
Reply: No.
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Interpretation XI-1-95-48R:
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Reply: Yes.
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Question (1): When replacing a valve disc, do the requirements of IWA-5214(e) apply?
Reply (1): No.
Question (2): When replacing any pressure-retaining part of
a valve that is internal to the valve body/bonnet, do the
requirements of IWA-5214(e) apply?
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Reply (2): No.
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Question: When replacing a valve bonnet and/or body which
requires the mechanical disassembly and reassembly of the
valve, is it the intent of Section XI that the requirements of
IWA-5214(e) apply?
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The fifth and sixth interpretations present questions regarding
IWA-5214(e) and the same questions regarding IWA-4710(c),
which is the paragraph in the 1991 Addenda that replaced IWA5214(e). These interpretations dealt with specific examples rather
than the more general question of Interpretation XI-1-89-37.
Consequently, these two interpretations are very important in
determining what pressure tests are required when the item being
replaced is inside the component and not visible for a meaningful
pressure test. The reference to IWA-5214(e) applies to the 1980
Edition with Winter 1980 Addenda through the 1989 Edition with
1990 Addenda, whereas the reference to IWA-4710(c) applies to
the 1989 Edition with 1991 Addenda through the 1995 Edition.
Interpretation XI-1-95-48R, especially, should eliminate many
meaningless VT-2 examinations performed on replacements that
are internal to a valve. The same logic provided in XI-1-95-48R
should be applied to similar components, such as a pump, to eliminate these meaningless VT-2 examinations on internal items. The
interpretations are as follows. Interpretation XI-1-95-66:
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Reply: No.
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Question: Is it a requirement of IWA-5214(e) to pressurize
replacement items installed by mechanical means that are not
subject to pressurization during a Class 2 system functional
or inservice test?
IWA-4540(a), as part of the rewrite of IWA-4000 in the 1995
Addenda, included an editorial clarification to note that brazing
activities were included in the pressure testing requirements.
Brazing had not been included in the pressure test requirements,
but it was clearly considered a repair since the 1988 Addenda
(refer to the brazing discussion in Section 27.10). Most
Committee members agreed that the intent of Section XI was for
repair by brazing and installation of replacements by brazing to
require a hydrostatic test unless exempted by the hydrostatic pressure test exemptions in IWA-4000. Therefore, the editorial
clarification to include brazing in the pressure testing requirements should not be considered a new Code requirement.
The 1999 Addenda made several changes to the Section XI
pressure testing requirements. Most of the changes will be discussed in the forthcoming paragraphs with some comments on the
current requirements. The 1999 Addenda also revised the exemptions for pressure testing. The exemption changes will be discussed in Section 27.11.3.2.
In the 1999 Addenda, the previous IWA-4540(c) requirement to
perform a pressure test and VT-2 examination of mechanical
joints made in the installation of pressure-retaining replacement
items was deleted. The logic behind this deletion was that this
requirement was no longer needed because the test was only at
operating pressure, the Owner’s operational procedures already
did this type of inspection, and leakage at a mechanical connection was usually corrected by such maintenance activities as tightening the bolting. Unfortunately, in the United States the NRC did
not consider this to be an appropriate deletion. The federal regulation was changed to mandate that Licensees who were required to
update their Repair/Replacement Programs to the 2001 Edition
and later editions and addenda of Section XI must also apply the
repair/replacement activity requirements of IWA-4540(c) in the
1998 Edition for pressure testing of Class 1, 2 and 3 mechanical
joints, essentially eliminating the Code deletion of IWA-4540(c).
However, because the NRC overlooked the deletion of IWA4540(c) when approving the use of the 1998 Edition through the
2000 Addenda, Licensees that were required to update their
Repair/Replacement Programs to the 1998 Edition through the
2000 Addenda may use the IWA-4540 provisions as published,
effectively allowing the deletion of IWA-4540(c) [15].
The 1999 Addenda also incorporated Code Case N-416-1,
which allowed the alternative of a system leakage test in lieu of a
hydrostatic pressure test of IWA-4000 for welded repair and
installation of replacement items by welding. In a compromise
with the NRC in order to obtain NRC approval of Case N-416-1,
the Case imposed the NDE methods and acceptance criteria of the
1992 Edition of Section III, which were considered adequate by
the NRC to ensure acceptability of the welds, without the hydrostatic pressure test if the system leakage test at operating pressure
(as required by the 1992 Edition of Section XI) was performed.
The specification of the 1992 Edition of Section III was to impose
minimum NDE requirements regardless of the Construction Code
involved. The 1992 Edition of Section XI was to ensure use of the
rewrite of IWA-5000 published in the 1991 Addenda. Use of this
Code Case can result in significant cost savings to Owners; consequently, it has been used widely by the industry.
The approval of Case N-416-1 for use in the United States
included an NRC-imposed condition for Class 3 welds that
required a Section III final surface examination by the magnetic
particle or liquid penetrant methods. For these welds, the NRC
required that the root pass of the weld be examined by the magnetic-particle or liquid penetrant method unless radiography or
Y
Interpretation XI-1-01-37:
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Question (3): When replacing a valve disc, do the requirements of IWA-4710(c) apply?
Reply (3): No.
Question (4): When replacing a valve bonnet and/or body
which requires installation by mechanical joints, do the
requirements of IWA-4710(c) apply?
Reply (4): Yes.
Question (5): When replacing any pressure-retaining part of
a valve that is internal to the valve body/bonnet, do the
requirements of IWA-4710(c) apply?
Reply (5): No.
Several important changes have been made since the 1989
Edition. These changes have provided significant improvement
and clarity to the pressure testing requirements.
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Question (5): Is it a requirement to perform duplicate nondestructive examinations using the same method when a single
exam would fulfill Code Case N-416-1, the Construction
Code, and the Owner’s Requirements?
Reply (5): No.
Question (6): Is it a requirement of Code Case N-416-1 that
acceptance criteria specified in the 1992 Edition of Section
III be used regardless of the NDE technique used?
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Reply (6): Yes.
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Reply (7): Yes.
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Question (7): If the Owner’s Requirements impose a NDE
method(s) in addition to those specified in the 1992 Edition of
Section III, is it a requirement when using Code Case N-416-1
that the additional requirements be met?
Interpretation XI-1-95-45, which follows, addresses the use of
related requirements in the 1992 Edition of Section XI when performing the inservice leak test in accordance with the 1992
Edition of Section XI.
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Question: Is it a requirement of ASME Code Case N-416-1,
that IWA-2000 of the 1992 Edition of Section XI be used when
performing VT-2 examinations?
Reply: No, only IWA-5000 requirements of the 1992 Edition
are applicable.
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other approved volumetric examination was performed.
Subcommittee XI considered the proposal to do root pass examinations both during the approval of Case N-416-1 and in the action
to incorporate the Case into IWA-4540, as published in the 1999
Addenda. Both times, Subcommittee XI did not consider the additional examination of the root pass necessary to eliminate the
hydrostatic test. Regardless of the Subcommittee XI position, for
Case N-416-1 to be used in the United States, the NRC condition
must also be used. However, in Regulatory Guide 1.147 Rev. 13
[5], the NRC condition for examination of the root pass was eliminated with the conditional approval of Case N-416-2. Therefore,
use of Code Case N-416-2 can be an important update to an
Owner’s Repair/Replacement Program.
During consideration of the action to incorporate Code Case
N-416-1, the Section XI Subgroup on Repairs, Replacements, and
Modifications requested that the existing hydrostatic test continue
to remain in the Code as an alternative to performing the examinations required by the Case rather than having the hydrostatic test
completely deleted. For some replacements, such as a piping subassembly with end flanges, a hydrostatic test may be easy to perform and more economical than the examinations required by the
Case and the NRC conditions for use of the Case. As a result, IWA4540 in the 1999 Addenda allowed the option of using either the
hydrostatic test or the incorporated provisions of Case N-416-1.
Several interpretations that provide clarification on use of
Code Case N-416-1 are provided to assist the user in implementing Code Case N-416-1 and the provisions of the 1999
Addenda through the 2002 Addenda. Interpretation XI-1-98-01
has several questions that provide clarification regarding the
NDE requirements of Code Case N-416-1. Interpretation
XI-1-98-01 contains a figure showing the numerous examinations that could be required by Owner’s Requirements, the
Construction Code, and Code Case N-416-1. The figure may be
of interest, but it is not essential for understanding the interpretation and therefore has not been included in this chapter. (The
figure is on page 361 of Section XI Interpretations, vol. 42,
which is included with the 1998 Edition of Section XI.)
Interpretation XI-1-98-01 follows.
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Some other interpretations on the use of Code Case N-416-1
follow.
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Question (1): When implementing Code Case N-416-1, is the
Owner required to have determined the Code Classification
of the repaired/replaced component in accordance with IWA1400(a)?
Reply (1): Yes.
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Question (2): Is it a requirement of Code Case N-416-1 that
Code classification determined in Question (1) be used to
determine the NDE method and acceptance criteria used in
the 1992 Edition of Section III?
Reply (2): Yes.
Question (3): Is it a requirement of Code Case N-416-1 that
only the NDE method (as defined in Section V) and acceptance criteria from the 1992 Edition of Section III be used?
Reply (3): Yes.
Question (4): Does Code Case N-416-1 specify the NDE techniques associated with the required NDE methods specified in
the 1992 Edition of Section III?
Reply (4): No. NDE techniques permitted by the Construction
Code or later editions or addenda, thereof, may be used.
Interpretation XI-1-98-64:
Question: When performing a system leakage test in lieu of a
Section XI hydrostatic test in accordance with Code Case
N-416-1 following installation of a NPT-stamped Class 1
replacement part by welding, may the NDE specified in
NB-5410 be performed prior to the system leakage test?
Reply: Yes.
Interpretation XI-1-95-37:
Question: Is it a requirement that when performing a system
leakage test on Class 1, 2, or 3 pressure-retaining components, in accordance with Code Case N-416-1, that the test
temperature be equal to the nominal operating temperature
for the system?
Reply: No. The test temperature is determined by the requirements of IWA-5111(a), IWA-5212, IWB-5240, IWC-5240, and
IWD-5230, to meet fracture prevention criteria.
Interpretation XI-1-95-12:
Question: When using Code Case N-416-1 is it a requirement
that, in addition to the NDE specified in the Case, the NDE
requirements specified in the Owner’s Requirements shall
also be met?
Reply: Yes, the Owner’s Requirements are defined in the 1993
Addenda to the 1992 Edition.
Probably the most confusing area of pressure testing has
involved pressure tests required for replacement items. As noted
at the beginning of Section 27.11.3.1, Section XI wording in the
1991 Addenda and later has clearly addressed pressure testing of
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IWA-4540 (or the equivalent paragraphs in earlier editions and
addenda) or N-416-1 were to be applied to the welds. For replacement item welds not considered to be installation welds, and for
the broader question of what requirements apply to replacement
NPT-stamped parts that were not pressure tested prior to stamping,
the interpretation noted that there are no specific requirements in
Section XI for pressure testing of these welds/parts. However, the
interpretation additionally noted that Section XI as far back as the
1985 Addenda had required the Owner or Repair/Replacement
Organization to include in the Repair/Replacement Plan the
applicable examination, test, and acceptance criteria to be used to
verify acceptance of the replacement item.
While the previously discussed 1999 Addenda changes to
IWA-4540(a) had used the general wording of “repair/replacement activities performed by welding or brazing on pressureretaining boundary”, Code Case N-416-1 had use more specific
wording of “welded repairs and installation of replacements items
by welding”. Therefore, no change was needed to IWA-4540 to
incorporate the clarification of interpretation XI-1-98-61.
However, the specific wording in N-416-1 made a revision of the
Case appropriate in order to incorporate the clarification of the
interpretation. The revision, published as Case N-416-2, included
wording to address fabrication welds for replacement parts and
piping subassemblies.
About this same time, it was identified that the specific wording
of N-416-1 also made it unclear whether the Case included
repair/replacement activities performed by brazing. Therefore,
intent interpretation XI-1-98-76 was prepared and subsequently
approved, which clarified that it was the intent of Case N-416-1 to
include brazing. Accompanying the approval of intent interpretation XI-1-98-76 was another revision to Case N-416-1, which was
published as N-416-3. Case N-416-3 added wording to address
brazed repairs, brazed fabrication joints for replacement parts and
piping subassemblies, and installation of replacement items by
brazing. As noted earlier in this Section 27.11.3.1, brazing had
been added to IWA-4540(a) in the 1995 Addenda, so no similar
changes were needed to IWA-4540.
In the 2002 Addenda, Section XI was finally revised to
specifically include requirements for the pressure testing of
replacement parts and piping subassemblies. Brazed joints and
welds in replacement parts and piping subassemblies fabricated
by the Repair/Replacement Organization, or fabricated in accordance with the Construction Code without a hydrostatic pressure
test, were required by the revision to be tested to the same
requirements as other repair/replacements performed by welding
or brazing.
This same revision in the 2002 Addenda also made several
other changes to IWA-4540 and a related change to IWA-5120.
These changes: 1) required that replacement components and
appurtenances be pressure tested in accordance with the
Construction Code selected for use; 2) identified the timing of the
hydrostatic test and the leakage test; 3) incorporated interpretation
XI-1-98-52R, which clarified that the entire system does not need
to be subjected to a VT-2 examination when the area of a
repair/replacement activity is not isolable; and 4) deleted the
redundant subsubarticle IWA-5120, System Pressure Tests for
Repair/Replacement Activities.
In the 2003 Addenda, IWA-4540(a) was revised to delete the
requirements for use of the methods and acceptance criteria of the
1992 Edition of Section III as a condition to perform a leakage test
at operational pressure. A similar change was made to Case
N-416-3 and was published as Case N-416-4. After several years
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welded repairs, installation of replacement items by welding, and
installation of replacement items by mechanical connections. But
what were the pressure tests for the item to be used for replacement? This was a question that Section XI never clearly addressed
until the 2002 Addenda. Because many Owners are using Section
XI editions and addenda earlier than the 2002 Addenda, the following several paragraphs should be helpful in clarifying this
question.
Section XI requires replacement items to meet the Construction
Code. These replacement items may be purchased as material,
parts, components, or appurtenances. However, Section III in NX6111 provides pressure testing requirements only for components
and appurtenances. Section III has stated through interpretations
that if the item is a part, it need not be pressure tested to satisfy all
of the Section III fabrication requirements (see Section III
Interpretations III-1-83-165, III-1-89-38, and III-1-81-134).
Furthermore, Interpretations III-1-86-95 and III-1-89-24 clarify
that Section III does not address pressure testing of NPT-stamped
parts installed as replacement items in N-type stamped components. In B31.1 or B31.7 Codes, there are also no requirements
for pressure testing subassemblies other than what would be
applied to a completed piping system.
Before the 1999 Addenda, Section XI pressure testing requirements applied to “welded repairs and installation of replacement
items by welding” (reference IWA-4540 and Code Case N-416-1).
Neither this Section XI wording nor previous Section XI interpretations provided a clear position on the subject of pressure testing
of parts. Therefore, requirements for pressure testing of fabrication welds for parts was not clearly stated in either the
Construction Code or Section XI. However, it has long been the
utility industry practice (implemented with Authorized Inspection
Agency approval) to categorize welds that assemble a piping subassembly at the Owner’s facility as “installation welds,” made for
convenience in the shop to improve the conditions for welding
and also to reduce radiation exposure. This practice was consistent with provisions in the definition of installation in Section XI,
which included those actions required to join items of a nuclear
power system by welding or mechanical means.
In 1999 and 2000, Subcommittee XI considered a request for
interpretation on the pressure test requirements for replacement
part fabrication welds, such as piping subassembly welds. The
resulting two interpretations were very important to the industry
because many Owners and Repair/Replacement Organizations
and their Authorized Inspection Agencies had understood Section
XI and Case N-416-1 to cover replacement piping subassembly
welds and other replacement parts, as well as the welds to install
the piping subassembly or part; thus they implemented Section XI
and the Case accordingly. Interpretation XI-1-98-61, which follows, is the first of these two interpretations and is applicable to
Section XI and Code Case N-416-1.
Question: Does the Section XI term “installation” allow the
joining of items, by the Owner or Repair/Replacement
Organization, into a piping subassembly at a location other
than its final location in the piping system?
Reply: Yes.
The second interpretation was XI-1-98-73. The questions and
replies in this interpretation address what requirements apply for
replacement parts and piping subassemblies fabricated prior to the
installation activity. For replacement item welds that were considered to be installation welds, the pressure testing requirements of
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of experience, it was concluded that the use of the NDE requirements of the Construction Code used for the repair/replacement
activity was adequate without the imposition of the 1992 Section III
NDE requirements. The discussion earlier in this section provided
the basis for the original compromise that resulted in the inclusion
of the Section III NDE in Case N-416-1 and later in the incorporation of Case N-416-1 in the 1999 Addenda. It also noted that the
option of performing a hydrotest in lieu of leakage test was
retained because in some situations, the hydrotest may be easier
than the 1992 Section III NDE. With the deletion of the 1992
Section III NDE, there are fewer situations where a hydrotest
would be advantageous.
In the 2005 Addenda, clarifications regarding fabrication by a
Repair/Replacement Organization were finally added to fully
incorporate the 1999 Addenda change to IWA-4143. The IWA4143 change allowed Repair/Replacement Organizations to fabricate parts for the Owner at the Owner’s facility (see Section
27.5.3 for additional information). However, by the 2005
Addenda, the changes to IWA-4540 discussed in the previous
paragraphs to add or clarify pressure testing of parts had already
been made and no additional change was necessary in IWA-4540
to clarify fabrication.
that removing and installing a seal weld was not a Section XI
repair or replacement. Subcommittee XI concluded that the installation of a seal weld should be covered under the rules of IWA4000, but that there was no need to require a pressure test for such
a weld. Interpretation XI-1-83-28R follows.
27.11.3.2 Exemptions from Pressure Testing IWA-4540(a), in
the 2007 Edition, requires that repair/replacement activities performed by welding or brazing on a pressure-retaining boundary
shall include either a hydrostatic pressure test or a system leakage
test unless exempted by IWA-4540(b). The exemptions in IWA4540(b) are intended to eliminate pressure testing of repair/replacement activities where experience has shown that little benefit is
obtained for the difficulty and expense of performing the pressure
test. Historically, the exemptions to pressure testing in IWA4540(b) have originated in the Summer 1978 Addenda, at which
time exemptions to the hydrostatic test following repair were added
as IWA-4400(b). For replacements, IWA-7400 exempted NPS 1
and smaller piping, valves, and fittings from the requirements of
IWA-7000 and, therefore, from the welded installation and pressure
testing requirements of IWA-4000. Discussion and inclusion of
several interpretations on the IWA-7400 NPS 1 and smaller exemption were presented in Section 27.4.1 of this chapter; therefore, that
exemption is not discussed here. The changes in the exemptions for
pressure testing following repair are discussed in the following
paragraphs.
Before the 1999 Addenda, five changes were made to the pressure test requirements for repair since the inclusion of IWA4400(b) in the Summer 1978 Addenda. These changes were the
addition of an exemption for tube-to-tubesheet welds when such
welds are made on the cladding (added in the Winter 1982
Addenda); revision to clarify that repair welds made using the
Section XI half bead welding techniques may not be exempted
from the hydrostatic test (included in the Winter 1982 Addenda;
note, however, that the clarification allowed the hydrostatic pressure test exemption to apply to a Section III temper bead repair
allowed by the Section XI reference back to the Construction
Code); deletion of the provision that prevented use of the exemptions when performing Section XI half bead welding (included in
the 1989 Addenda); addition of an exemption for seal welds
(added in the 1989 Addenda); and addition of an exemption for
heat exchanger sleeving (added in the 1992 Addenda).
The addition of an exemption from pressure testing for seal
welds was made in 1989, the same time that an old interpretation
was being debated. Interpretation XI-1-83-28 previously stated
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Reply: Yes.
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In the 1999 Addenda, the exemptions for pressure testing were
revised. Three new exemptions were added, and two exemptions
were reworded. The first added exemption was IWA-4540(b)(4),
which addressed welding on a flange surface. This was the incorporation of intent interpretation XI-1-89-31, which follows.
Question: Is it the intent of Section XI, IWA-4400(a)(3) that a
weld repair across the entire width of a seating surface of a
raised-face flange require a system hydrostatic test?
Reply: No.
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The second added exemption was IWA-4540(b)(9), which
addressed welded joints between non-pressure-retaining items and
pressure-retaining items, which was included more for clarity than
for any new requirement because most users already exempted
such welds. A revision in the 2002 Addenda also added brazed
joints to the exemption. The third added exemption addressed
valve disks and seats. Performance of pressure tests on these internal items was impractical and of little value. In addition, the
Owner’s Pump and Valve Test program would require leak testing
of valves where leakage past the disk was important regardless of
whether the Repair/Replacement Program required a pressure test.
IWA-4540(b)(5) and (6) were reworded in the 1999 Addenda,
but the intent was not changed. A comment is appropriate for the
rewording of IWA-4540(b)(6). The wording changed from “component connections, piping, and associated valves NPS 1 and
smaller” to “components or connections NPS 1 and smaller.” In
accordance with the Section XI definition of component, a piping
system is a component, but a particular piping run of NPS 1 and
smaller does not always constitute a piping system and would not
usually be interpreted as a component, thereby prohibiting this
exemption for such small piping runs. Although Owners who
adopt the IWA-4131 alternative will not be using IWA-4540 (use
of the IWA-4131 alternative replaces most of IWA-4000) for
Class 2 and 3 NPS 1 and smaller items, they may have Class 1
piping NPS 1 and smaller for which they cannot use IWA-4131
and must apply IWA-4540. Also, if Owners do not apply IWA4131, they would have Class 1, 2, and 3 piping NPS 1 and smaller
for which they are required to apply IWA-4540. Section XI
always exempted these small piping sizes from pressure testing,
and this author’s opinion is that the intent of the reworded IWA4540(b)(6) is still to exempt piping NPS 1 and smaller from pressure testing. This question is anticipated to be eventually posed to
Subcommittee XI and a clarification either by interpretation or by
a Code change will be forthcoming.
Two other interpretations regarding IWA-4540(b) are worth
noting. The first relates to the previous discussion on component
connections and clarifies a common question on the exemption
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Question: Is the removal of a seal weld, that is between the
body and bonnet of a valve and is not pressure retaining, and
its subsequently welded back (after servicing the valve internals), considered a repair or replacement under the rules of
Section XI, Division 1, IWA-4000 or IWA-7000?
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for component connections, piping, and associated valves that are
NPS 1 and smaller. IWA-4400 referred to in Interpretation
XI-1-83-58, which follows, is the location of the pressure testing
exemptions before the 1988 Addenda. However, the interpretation
is still applicable to the later Code editions and addenda where the
exemptions have been relocated to different paragraphs.
ALTERNATIVES TO CONSTRUCTION
CODE WELDING
As noted early in this chapter, the 1972 discovery of flaws during a preservice examination of a new reactor vessel identified the
need for special Section XI requirements when the Construction
Code requirements could not be met for making a repair. Out of
the five specific repair techniques added to Section XI in the
Summer 1973 Addenda, two specifically addressed conditions
when the Construction Code postweld heat treatment requirements could not be met following a welded repair. These two
repair techniques were called half bead weld repair techniques.
Since 1973, revisions have been made to these techniques, such as
changing the half bead weld technique to the temper bead weld
technique and additional techniques have also been added; for
example, gas tungsten-arc temper bead welding was added to
IWA-4000 in the 1991 Addenda when most of the provisions of
Code Case N-432 were incorporated. The use of Code Case
N-432-1 should be reviewed when considering temper bead welding because it has two important changes from N-432. Case N432-1 (and its incorporation into Section XI in the 2003 Addenda)
reduced the number of required layers from six to three and
removed the 48 hour hold before performing NDE. In the 1988
Addenda through the 1995 Edition, the alternative welding methods were located to IWA-4500. These alternative welding methods were relocated to IWA-4600 in the 1995 Addenda.
The requirements for the alternative welding methods included
in IWA-4600 are written in considerable detail, constituting nearly one-half of the pages included in IWA-4000 in the 2007
Edition. These alternative welding methods are specialized, making them both difficult and expensive to perform. Experienced
welding engineers should be consulted for the use of these methods. Therefore, these methods will not be discussed in detail in
this chapter; the discussion here will provide only a general
overview.
IWA-4600 includes the following alternative welding methods:
temper bead welding on similar materials using shielded metalarc welding or gas tungsten-arc welding; temper bead welding on
dissimilar materials using shielded metal-arc welding or gas tungsten-arc welding; temper bead welding on cladding materials
using shielded metal-arc welding or gas tungsten-arc welding;
butter bead-temper bead welding using shielded metal-arc welding; and underwater welding of ferritic and austenitic materials
using either dry underwater welding or wet underwater welding.
The requirements of IWA-4600 are used in lieu of the welding
and nondestructive examination requirements of the Construction
Code.
The first four of the aforementioned alternative welding methods provide alternatives to meeting the postweld heat treatment
(PWHT) requirements of the Construction Code. In other words,
these welding methods are used only when it is not practical to
perform the PWHT required by the Construction Code after the
repair/replacement activity welding. The PWHT requirements of
the various Construction Codes apply to ferritic materials and are
based on the P-No. classification of materials as defined in
Section IX, QW-420, material nominal thickness, material properties, and minimum preheat applied before welding. The most likely use of these alternative welding methods is on heavy-wall pressure vessels, such as reactor vessels, steam generators,
pressurizers, or some Class MC metal containments, or on ferritic
reactor coolant system piping that has been clad or overlayed. The
temper bead process is tightly controlled and qualified so that
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Question: Is it a requirement of IWA-4400 of the 1980 Edition
of Section XI, with the Winter 1980 Addenda, that welds connecting piping and associated valves that are NPS 1 and
smaller to existing larger diameter piping or components be
subjected to a system hydrostatic test?
27.12
The second interpretation, XI-1-83-37R2, clarifies a sometimes
held idea that even if the hydrostatic test is exempted, a pressure
test at operating pressure is still required to be documented.
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Question: Does Section XI require some type of pressure test,
as defined in IWA-5000, on a component that has been
repaired or replaced, and is exempted from a system hydrostatic pressure test by IWA-4400(b) or IWA-7400?
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Reply: No. IWA-4400(b)(5) exempts welds connecting component connections, piping, and associated valves that are
NPS 1 and smaller to existing larger diameter piping and
components from a system hydrostatic test.
Reply: No.
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In the 2007 Edition, the IWA-4540(b) exemptions were revised
to incorporate a change regarding the pressure test exemption for
pressure vessels, most recently contained in IWA-4540(b)(5) in the
1999 Addenda through 2006 Addenda. The history on this exemption goes back to the Summer 1978 Addenda. In the Summer 1978
Addenda, IWA-4000 was revised to provide more detailed repair
procedures. Part of that revision was to add exemptions from postrepair hydrostatic testing. That revision allowed repairs in pumps,
valves, and piping to go nearly through the wall without a hydrostatic test, but limited vessel repairs without a hydrostatic test to
10% through the wall. Since that time, the post-repair hydrostatic
test has been replaced by a nominal operating pressure leak test.
The Subgroup on Repair/Replacement Activities could find no
technical basis for the limitation in the Summer 1978 Addenda,
resulting in the limitation for vessels being arbitrarily more conservative than that for piping, pumps, and valves. In addition, there
was no technical basis for requiring more vessel repairs to be
hydrostatic tested especially because the required hydrostatic test
was not intended to challenge the structural integrity of the component. Structural integrity is demonstrated by the design and the
applicable nondestructive examination (which varies with Code
Class and welding method used). The revision and the basis for the
revision were approved by Subcommittee XI and the BPV
Standards Committee and published in the 2007 Edition.
The resulting revision changed the requirements for pressure
testing of vessel repair/replacement activities to be consistent with
those for piping, pumps, and valves. To implement this revision
regarding pressure vessel pressure testing and provide that consistency, IWA-4540(b)(3) was revised from “piping, pump, and
valve welding or brazing that does not penetrate through the pressure boundary” to “welding or brazing that does not penetrate
through the pressure boundary”. As a result of this consolidation
of IWA-4540(b)(3) and (b)(5), IWA-4540(b)(5) was deleted and
(b)(6) through (b)(10) were renumbered (b)(5) through (b)(9).
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when the butter bead-temper bead welding process of IWA-4650
is used to weld Class MC vessels or Class CC metallic liners.
There are three important Code Cases that provide additional
alternatives to the Section XI specified preheat requirement and
the requirement to maintain the weld at an elevated temperature
for a specified hold time, as noted above. Code Case N-740, and
later revisions of the Case, address ambient temperature machine
GTAW temper bead welding techniques for application of weld
overlays (refer to Section 27.10.1.2 for further information). Code
Cases N-606-1 and N-638 address ambient temperature machine
GTAW temper bead techniques when it is impractical, for operational or radiological reasons, to drain the component. With water
backing (i.e., if the component is not drained) it is not practical to
reach and maintain the IWA-4600 preheat requirement and the
elevated temperature hold time requirement. Code Case N-606-1
is a specific Case for boiling water reactor control rod drive housing or stub tube repair; Code Case N-638 is a general Case for
any ambient temperature machine GTAW temper bead technique
when it is impractical, for operational or radiological reasons, to
drain the component. Code Case N-638 was revised and published as Case N-638-1 to expand the limiting condition in N-638
that only allowed it to be used when it was impractical to drain
the vessel. Case N-638-1 permits repair/replacement activities
without the specified preheat and post-weld heat treatment of the
Construction Code when it is impractical to do so for radiological
reasons.
Other important changes were subsequently made to N-638-1,
such as increasing the maximum area of the weld from 100 square
inches to 500 square inches (N-638-3), and changing the start of the
48 hour hold time before performing the NDE for austenitic material to completion of the three tempering layers rather than completion and cooling of the weld to ambient temperature (N-638-4).
When using the alternative welding methods of IWA-4600,
some of the provisions of IWA-4400 must also be used. The 2001
Edition made significant changes and clarifications in the application of IWA-4400, IWA-4500, and IWA-4600 for these alternative
welding methods. The 2001 Edition also made important changes
to the NDE requirements for these alternative welding methods.
The fifth aforementioned alternative welding method covers
underwater welding. Both dry welding and wet welding are covered for ferritic and austenitic materials. Construction Codes
require controls on welding that cannot be met when there is a
need to perform repair/replacement activities on plant items located in an underwater environment. Therefore, IWA-4660 was
added in the 1996 Addenda to cover underwater welding of P-No.
8 and P-No. 4X austenitic materials, and it was revised in the
1997 Addenda to add underwater welding of P-No. 1 ferritic
materials. Unfortunately, the 1997 Addenda included an error in
the carbon equivalent formula in Fig. IWA-4663.1-1. All terms in
the formula were to be additive but the 1997 Addenda through the
2000 Addenda incorrectly showed (Mn+Si)/6 being subtracted
from C in the formula. This error was corrected by errata in the
2001 Edition. However, this errata was not identified in the
Summary of Changes in the 2001 Edition, nor was the margin by
the formula noted with the 01 change indicator. Code Case N516-1 contains the requirements included in the 1996 and 1997
Addenda and should be considered by Owners working to earlier
Section XI editions and addenda. In addition, Case N-516-3 revises the Case to add underwater laser beam welding.
The 2006 Addenda included changes to underwater welding
provisions to address the NRC limitation on underwater welding
of irradiated materials contained in 10 CFR 50.55a(b)(2)(xii), to
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weld beads temper the previously deposited beads and heat affected zone to achieve the required mechanical properties without
postweld heat treatment.
A few, but not all, of the controls and limitations applied to
these four alternative welding methods are noted here. IWA-4610
applies to each of these methods except the IWA-4650 butter headtemper bead process as discussed in the following paragraph.
IWA-4610 requires that the area to be welded plus a band around
the weld area of at least 1-12 times the component thickness or 5
in., whichever is less, shall be preheated and maintained at a minimum temperature of 350F for the shielded metal-arc welding
process and 300F for the gas tungsten-arc welding process. The
welding procedures and welders or welding operators are required
to be qualified in accordance with Section IX and the additional
requirements contained in IWA-4600 for each of the processes.
Each of the methods have detailed requirements for preparing a
test assembly, for testing of the test assembly to ensure that the
required tempering and material properties are being achieved, and
for performing the production welding and examinations following
the welding. IWA-4620 for similar material temper bead welding,
IWA-4630 for dissimilar material temper bead welding, and
IWA-4640 for cladding temper bead welding (when the ferritic
material is within 81 in. of being exposed), all require maintaining
the weld, or a portion of the weld, at an elevated temperature for a
specified hold time. In addition, IWA-4621, for similar material
temper bead welding, and IWA-4631, for dissimilar material temper bead welding, both limit use of the temper bead process to a
maximum area of 100 sq in. and a weld depth not greater than 12 of
the base metal thickness. There are also limitations on the materials on which these methods may be used.
Section XI IWA-4610(b) requires temper bead welding procedures and welders or welding operators to be qualified in accordance with Section IX and the additional requirements of IWA4600. Section IX added procedure qualification requirements for
temper bead welding in the 2004 Edition allowing those requirements be used when referenced by the applicable Code Section,
e.g., Section XI for repair/replacement activities. These Section
IX qualification requirements for temper bead welding were
revised in the 2006 Addenda to address concerns with use of the
requirements. Section XI Code Case N-762 was subsequently
approved (and published in Supplement 1 to the 2007 Nuclear
Code Case book) to allow the revised Section IX qualification
requirements for temper bead welding to be used in lieu of the
Section XI IWA-4600 temper bead procedure qualification
requirements, subject to several conditions listed in the Case.
Code Case N-651 is another Case applicable to temper bead
welding. It was published in Supplement 1 to the 2001 Nuclear
Code Case book. It applies to ferritic and dissimilar metal temper
bead welding using shielded metal-arc welding. The Case permits
the elimination of the grinding of the first layer of temper bead
welds when using shielded metal-arc welding. It is listed in
Regulatory Guide 1.147 [17] as approved without conditions.
The 2004 Edition corrected an error inadvertently imposed in
the 1995 Addenda on the use of the IWA-4650 process for butter
bead-temper bead welding for Class MC and for Class CC metallic liners. The 2004 Edition correction to IWA-4600(b)(2)
removed the requirements for this process to meet the preheat and
postweld heat treatment requirements of IWA-4610. This error
was also the subject of interpretation XI-1-04-20. This intent
inquiry is applicable to the 1995 Addenda through the 2003
Addenda and clarifies that it is not the intent of IWA-4600(b)(2)
to require IWA-4610 (which includes a 350 degrees F preheat)
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Question (1): Does IWA-4000 address mechanically installed
heat exchanger tube plug assemblies? (Applicability: 1992
Addenda up to and including the 2000 Addenda).
Reply (1): No
Question (2): Does IWA-4000 address Class 2 and 3 mechanically installed heat exchanger tube plug assemblies?
(Applicability: 2001 Edition up to and including the 2005
Addenda).
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IWA-4700 contains requirements for plugging and sleeving of
heat exchanger tubing. Similar to the alternative welding methods
included in IWA-4600, IWA-4700 includes considerable detail.
The plugging and sleeving requirements are specialized processes
that are difficult and expensive to perform. Performance of the
plugging and sleeving requirements of IWA-4700 may be best left
to vendors experienced in these methods. Therefore, these
processes will not be discussed in detail in this chapter; the discussion here will provide only a general overview.
The plugging and sleeving processes covered in IWA-4700
include the following: plugging by explosive welding; plugging
by fusion welding using shielded metal-arc welding, gas tungstenarc welding, or gas metal-arc welding; plugging by expansion;
sleeving by explosive welding; sleeving by fusion welding using
gas tungsten-arc welding, gas metal-arc welding, or laser beam
welding; sleeving by brazing; and sleeving by expansion.
IWA-4711 provides requirements for plugging by explosive
welding. It is applicable for Class 1 heat exchangers, but may also
be used for Class 2 and 3 heat exchangers. IWA-4712 provides
requirements for plugging by fusion welding and is applicable for
Class 1 heat exchangers. Because IWA-4712 states that it may be
used for Class 2 and 3 heat exchangers, the requirements of the
Construction Code or IWA-4712 may be used to perform fusion
welding of plugs. Neither IWA-4711 nor IWA-4712 invoke the
Construction Code for the plugging processes. The specific
requirements to be met are detailed in IWA-4711 and IWA-4712.
Mechanical tube plugs were exempt from repair/replacement
activities under Section XI requirements prior to the 1992
Addenda when the IWA-4131 alternative requirements for small
items replaced the exemption for NPS 1 and smaller items.
Interpretation XI-l-92-44 provides this clarification by noting that
mechanical plugging of heat exchanger tubing is exempt under
the NPS 1 and smaller provisions. It would apply to editions and
addenda earlier than the 1992 Addenda and states,
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PLUGGING AND SLEEVING OF HEAT
EXCHANGER TUBING
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27.13
depends upon friction or interference at the interface. These requirements standardize the provisions for Class 1 mechanical tube plugs
and were developed with the involvement of each of the Class 1
Nuclear Steam Supply vendors providing mechanical tube plugs in
the United States. These new provisions ensure that all Class 1
mechanical tube plugging performed in the industry meet a consistent set of requirements. Class 2 and 3 mechanical tube plugs were
not addressed by this Code change and can still be addressed under
the IWA-4131 alternative requirements for small items. As noted
above, it was not clear what requirements applied to Class 2 and 3
mechanical tube plugs if the alternative requirements were not used.
This issue of Class 2 and 3 mechanical tube plugs was finally clarified in 2005 with the approval of Inquiry IN05-14 (published as
Interpretation XI-1-04-30). Due to an error, an approved accompanying question was not published in Interpretation XI-1-04-30. The
Section XI approved questions and replies were as follows:
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delete provisions for alternative procedure qualification using
Charpy V-Notch testing in lieu of bend testing, and to make clarifications where requirements were not clear.
Reply (1): No
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A revision to XI-1-04-30 is expected to be issued to correct this
error as well as extend the applicability of Question (2) up to and
including the 2006 Addenda. A related intent inquiry regarding
material for Class 1 mechanical tube plugs, initially part of
Inquiry IN05-14, was approved as interpretation XI-1-07-17 and
will be published in Interpretation Volume 58. The accompanying
Code change incorporating the intent into IWA-4120(a) was
approved and published in the 2007 Edition of Section XI and is
discussed in Section 27.3.2.
IWA-4720 provides the requirements for sleeving of heat
exchanger tubing. Although required for Class 1 heat exchanger
sleeving applications, IWA-4720 may be used for Class 2 and 3
heat exchangers. Requirements for sleeving were first added to
Section XI in the 1989 Addenda. The NPS 1 and smaller size
exemption in IWA-7400 was not applicable to sleeving as
clarified by Interpretation XI-1-92-32, which follows. Rather than
being exempt, the interpretation noted that sleeving was not
addressed by Section XI before incorporation in the 1989
Addenda. Users working to an edition and addenda of Section XI
earlier than the 1989 Addenda will need to adopt a later Section XI,
or a portion of it, that contains the sleeving requirements.
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Question: If a heat exchanger tube is mechanically plugged,
and the tube is 1 NPS or less, is the replacement exempt per
IWA-7400(d) except that materials and primary stress levels
shall be consistent with the requirements of the applicable
Construction Codes?
Reply: Yes.
With the 1992 Addenda and later editions and addenda, there are
no exemptions specifically applicable to mechanical tube plugs. The
alternative requirements of IWA-4131 discussed in Section 27.4.1.2
can be used for mechanical tube plugs, but until recently it was not
clear what provisions were required for mechanical tube plugs if the
alternatives of IWA-4131 are not used.
However, the 2001 Edition added IWA-4713 for new requirements for Class 1 heat exchanger tube plugging by expansion. These
new requirements apply to mechanical tube plugging when the
mechanical roll or mechanical expander expansion method is used
to expand plugs into Class 1 heat exchanger tubes in tubesheets,
such that the plug is permanently deformed and the attachment
Question: If a heat exchanger tube is mechanically sleeved,
and the tube is 1 NPS or less, is the replacement exempt per
Section XI, IWA-7400(d) except that materials and primary
stress levels shall be consistent with the requirements of the
applicable Construction Code?
Reply: Section XI did not address mechanical sleeving in the
1986 Edition. Note: Starting with the 1989 Addenda, sleeving
rules were incorporated into Section XI, IWB-4300 (and were
moved to IWA-4420 in the 1991 Addenda). In the 1991
Addenda, IWA-4120 further clarified that the NPS 1 exemption
does not apply to heat exchanger sleeves.
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General information on the use of Code Cases is included in
Section 27.1. Code Cases contain useful alternatives to Code
requirements, and although they are not mandatory, they can be
important tools to assist Owners and Repair/Replacement
Organizations in performing repair/replacement activities.
Throughout this chapter, where there was a current Code Case
related to the subject being discussed, the discussion identified the
Code Case by number. If the provisions of the Case were incorporated into Section XI by revision, the edition and addenda that
incorporated the provisions of the Case were also identified.
Therefore, most of the Section XI Code Cases applicable to
repair/replacement activities already have been noted. Old Code
Cases incorporated in editions and addenda commonly used by
Owners, as well as some minor Code Cases not containing significant provisions, were excluded from this chapter. However, there
are several remaining significant Code Cases that are more appropriate to note separate from any discussion of current Section XI
requirements, for the Cases contain significant alternatives or new
technology that do not fit well with discussion of current Section
XI requirements. These Code Cases, and a brief explanation of
each, are noted in the forthcoming paragraphs.
Code Case N-557-1, “In-Place Dry Annealing of a PWR
Nuclear Reactor Vessel,” was prepared for use in improving material properties of the core region of a pressurized water reactor
affected by radiation embrittlement. It is expected to have limited
use in the United States because of the NRC regulatory requirements and the design and fabrication requirements used during
reactor vessel manufacturing. However, the Case was initiated at
the request of a nuclear plant Owner in the United States. Fullscale demonstration of the technology was conducted at a canceled nuclear plant by the requesting Owner in conjunction with
several organizations.
Code Case N-561-2, “Alternative Requirements for Wall
Thickness Restoration of Class 2 and High Energy Class 3
Carbon Steel Piping,” and Code Case N-562-2, “Alternative
Requirements for Wall Thickness Restoration of Class 3
Moderate Energy Carbon Steel Piping,” are very similar and will
be considered together in this discussion. These two Cases provide for localized weld overlay on the outside of piping and
fittings to restore acceptability of internal thinning or pitting
degradation, but are not to be used for degradation involving corrosion-assisted cracking or any other form of cracking. The Cases
provide the following four methods of determining the acceptability of a localized weld overlay: by design; by proof testing as a
piping product; by proof testing qualification for specific applications; and by prequalified design. The prequalified design is based
on actual proof testing performed during development of the
Cases. As the title of each Case indicates, the Cases differ in
scope; N-561-2 addresses Class 2 and high energy Class 3 piping,
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27.14
whereas N-562-2 only addresses moderate energy Class 3 piping.
Accordingly, the design provisions, the prequalified design provisions, and the water-backed application provisions differ between
the two Cases, but the other provisions of the Cases are essentially the same. These two Cases were intended to provide a
significant tool to Owners when thinning or through-wall pitting
leaks are identified during plant operation and when plant
Technical Specification allowed outage times for limiting conditions of operation cannot be met for a more standard repair or
replacement.
Code Cases N-561-1 and N-562-1, earlier versions of the current Cases, have not been accepted by the NRC and are listed in
Regulatory Guide 1.193 Rev.2[16] as not acceptable for generic
use. In an attempt to get NRC acceptance of the localized weld
overlays on piping and make this approach available for Owner
use, a new Case N-661, “Alternative Requirements for Wall
Thickness Restoration of Class 2 and 3 Carbon Steel Piping for
Raw Water Systems”, which was based on Code Case N-562-1,
incorporated provisions that have been accepted by the NRC for
use in limited—although fairly common—applications. NRC
acceptance of Case N-661 with conditions was provided in
Regulatory Guide 1.147, Rev. 15 [17] and will preclude the need
for individual Owners to submit regulatory relief requests for
such repair/replacement activities. Changes included in Code
Cases N-561-2 and N-562-2 were based on NRC acceptance of
Case N-661 and N-661-1 changes to address NRC conditions.
Additional changes were included in N-661-2 to make it consistent with N-561-2 and N-562-2. The NRC has not yet included
these versions of the Cases in the appropriate Regulatory Guide
so NRC approval for use or disapproval is not yet known.
Code Case N-589, “Class 3 Nonmetallic Cured-In-Place
Piping,” provides an alternative for restoring degraded buried
Class 3 piping by the use of a reinforced thermosetting resin
sleeve inserted into the original host pipe and cured to form a
cured-in-place pipe as the new pressure boundary. Case N-589-1
revised the original Case to add a second technique for installation of cured-in-place pipe. This second technique is a sprayed
form in which the thermosetting resin is sprayed on to a precleaned pipe surface, actually adhering to the surface of the pipe,
to form a cured-in-place pipe as the new pressure boundary.
Major changes were included in N-589-1 to differentiate the
inserted form and the sprayed form of cured-in-place pipe. The
cured-in-place pipe modification can be designed for a partially
deteriorated host pipe or a fully deteriorated host pipe in which no
credit is taken for the host pipe. The Case includes provisions for
design and analysis, installation, testing, and monitoring. The
technology on which the Case is based has been used extensively
for restoration of buried piping in nonnuclear applications and
may be a cost-effective alternative to the locating, excavating,
repair, and reburial of leaking buried piping.
Another important Code Case is Case N-662, Alternative
Repair/ Replacement Requirements for Items Classified in
Accordance With Risk-Informed Processes. It is associated with
implementation of risk-informed regulation 10CFR50.69. It is
discussed in Section 27.15 on Future Considerations and will not
be further discussed here.
Code Case N-666 allows weld reinforcement build-up over
inservice socket weld failures caused by fatigue. The weld
reinforcement build-up may be performed on-line to un-isolable
systems and therefore may prevent unplanned outages. Case
N-666 was published in Supplement 9 of the 2004 Nuclear Code
Case book.
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Although they are not sleeving processes, two Code Cases exist
that provide alternative repair processes for the restoration of heat
exchanger tubing by adding material to the inside surface of the
tubing. Code Case N-569-1, “Alternative Rules for Repair by
Electrochemical Deposition of Class 1 and 2 Steam Generator
Tubing,” and Code Case N-576-1, “Repair of Class 1 and 2 SB163, UNS N06600 Steam Generator Tubing,” should be considered with sleeving as possible techniques for resolution of degraded
heat exchanger tubes.
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for boric acid degradation caused by PWSCC in Class 1 components. Code Case N-729 and subsequent errata, revisions, and corrections published as N-729-1 were approved and published to
address the inadequacy of Section XI examination requirements
for reactor vessel upper head penetrations due to the Alloy
600/82/182 degradation. An additional errata to N-729-1 was
included in Supplement 4 to the 2007 Nuclear Code Case book.
Draft Code Case N-770 is in preparation to provide alternative
examination requirements for Alloy 82/182 butt welds in Class 1
applications. ASME Section XI is working with the MRP to
incorporate provisions similar to those in MRP inspection guideline documents. Draft Case N-770 currently includes examination
and frequency requirements for unmitigated welds and for several
repair/mitigation techniques, both for uncracked and cracked
welds.
Several repair/replacement activity Code Cases have been published or are in preparation to address repair of Alloy 600/82/182
degradation and mitigation of Alloy 600/82/182 materials to eliminate the susceptibility of future degradation. Cases already published are discussed in Section 27.14. Some of the repair/mitigation alternatives in preparation as probable future Code Cases
include the following. An alternative for optimized weld overlay
similar to Code Case N-740-1 but using part of the original base
material and weld in the design of the weld overlay is being
developed. It will result in a thinner weld overlay more suited to
larger diameter piping. An alternative to use weld inlay/weld
onlay is being developed. It places a resistant weld on the inside
diameter to isolate the susceptible Alloy 82/182 weld from the
reactor coolant. It is anticipated that other Code Cases will also
be prepared to provide alternatives for use of new, innovative
repair/mitigation techniques for addressing the Alloy 600/82/182
degradation.
A second future consideration is the growth in new nuclear
plant construction. Several countries have embarked on significant
new nuclear plant construction. Even in the United States there is
the improving likelihood that new nuclear plant construction will
be started soon. Although most new plant construction will
involve advanced light water reactor designs, new gas-cooled
reactor designs are being developed. In recognition of the likelihood of new gas-cooled reactors, and in particular the work in
South Africa on the pebble-bed modular reactor, Subcommittee
XI formed a Project Team on High Temperature Gas-Cooled
Reactors in 2004 to begin the rewrite of Section XI, Division 2 for
inspection and testing of gas-cooled reactors. In the area of
repair/replacement activities, these new high temperature gascooled plants create significant new challenges for material selection, welding and repair/replacement activities.
An additional challenge coming out of the potential for
significant new plant construction will be finding the necessary
technical personnel to staff these new projects. With the aging of
nuclear industry workforce in operating plants and the competition of new plant construction, shortages of experienced technical
personnel are anticipated. The nuclear industry, NRC, academia,
and standards developing organizations such as ASME, need to
address the availability of technical personnel as one of the many
challenges to be solved, even if new nuclear plant construction
does not materialize as rapidly as anticipated.
A third future consideration is the growing use of risk-informed
technology to improve the safety of current and future nuclear
plants while reducing the costs and focusing available resources to
safety significant areas. Section XI committees have spent considerable time and resources over the past several years to support the
27.15
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Case N-730 was published in Supplement 11 of the 2004
Nuclear Code Case book with an errata included in Supplement 4
of the 2007 Nuclear Code Case book. Case N-730 allows use of
the mechanical roll expansion process for sealing of BWR bottom
head penetrations as a repair/replacement activity. The Case is
including the technology that has been successfully used for this
application over the last decade to address leakage due to penetration seal weld cracking. The Case specifies the technical and
administrative requirements, including process qualification,
essential variables, process application, and examination requirements, for application of this process.
As part of Subcommittee XI work to address the Alloy
600/82/182 degradation issue discussed in Section 27.15, some
repair/replacement Code Cases have been developed and published. Code Case N-733 provides provisions for use of mechanical connections to disposition leaking, small bore, Alloy
600/82/182 partial penetration welded nozzles in components in
the primary coolant system. Case N-733 was published in
Supplement 6 of the 2004 Nuclear Code Case book. Code Case
N-740, including subsequent revisions, were prepared to address
repairs and mitigation by weld overlays over existing Alloy 82/182
weld joints, where base materials may involve carbon steel, low
alloy steel, stainless steel or Alloy 600. Section 27.10.1.2 provides
more information on Case N-740 and its later revisions.
Code Case N-755, Use of Polyethylene Pipe for Section III,
Division 1, Construction and Section XI Repair/Replacement
Activities, was published in Supplement 1 of the 2007 Nuclear
Code Case book. The Case provides for the use of polyethylene
pipe for buried Class 3 applications for both new construction and
replacements. It includes technical and administrative requirements for materials, design, installation, examination, and pressure testing and is of interest to Owners because of its resistance
to erosion and corrosion common in buried piping systems.
FUTURE CONSIDERATIONS
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This section will discuss some of the future considerations in
the area of repair/replacement activities.
One area in which work has been ongoing for the past few years
is the issue of inservice degradation of Alloy 600 and its associated
Alloy 82 gas tungsten arc welding (GTAW) filler material and
Alloy 182 shielded metal arc welding (SMAW) filler material.
Repair and mitigation of the primary water stress corrosion cracking (PWSCC) of Alloy 600/82/182 is a major repair/replacement
activity challenge. As discussed in the second edition of the
Companion Guide, ASME Subcommittee XI has been working
with the industry’s Materials Reliability Program (MRP) organization to address areas where Section XI has inadequate examination
and repair/replacement requirements for addressing this degradation. Chapter 44 of the Companion Guide has an extensive discussion of Alloy 600 degradation. Readers will find the information in
Chapter 44 very useful in describing the Alloy 600/82/182 issue,
including examination, repair and mitigation strategies.
ASME has published changes and Code Cases to address some
of the Alloy 600 degradation. ASME Code Case N-694 and
N-694-1 address evaluation of flaws in reactor vessel head penetrations and were incorporated in Section XI IWB-3660 in the
2004 Edition and 2005 Addenda, respectively.
This third edition of the Companion Guide provides the following updates on ASME Section XI actions to address Alloy 600
degradation. Code Case N-722 was issued to address examinations
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are probably treating the items under their deterministic non-safety related classification system.
LSS, Class 1, 2, and 3 safety-related and non-safety related items
were both included in the scope of structural integrity requirements.
The risk-informed process has determined them to be of low safety
significance, but with the NRC requirements for the risk-informed
process, these items must be treated so as to remain functional. The
principle of N-662 is to ensure that these items have sufficient Code
requirements such that they are still expected to meet functional
requirements, albeit at a reduced level of assurance.
It is expected that a large percentage of Code Class 1, 2, and 3
items in current plants could be classified as RISC-3 items. Using
Case N-662 for these items could substantially reduce the cost for
procuring and installing these items without a reduction in safety.
For this reason, it was expected that as the industry and NRC
worked out the remaining details for use of 10CFR50.69, many
Owners would spend the resources to reclassify items in their
plants using the 50.69 processes. This was expected to result in a
substantial reduction in the number of items that use the
repair/replacement activity requirements in Section XI, but it
would allow Owners to focus available resources on items that
contribute the most to safe operation of the plants.
This however has not occurred as expected, with no Owner,
other than early pilot efforts, actually moving forward to implement the 10CFR50.69 provisions. The high initial cost of reclassifying, combined with the uncertainties in actual implementation,
and considerations for financing new nuclear plant construction,
have been reported as some of the reasons for no current use of
these risk informed provisions.
A fourth future consideration, although not nearly as significant
as the preceding three, has become obvious in the last couple of
years. During refueling outages, Owners may perform large
amounts of maintenance and modification work, especially in the
containment building. Repair/replacement activities often involve
performing radiography as the nondestructive examination
method used for acceptance of the welding. Radiography in the
containment building often requires evacuation of many workers
for radiological safety reasons. Using ultrasonic examination in
lieu of radiography would allow Owners to safely assess the
acceptance of the welding without the detrimental work stoppage
caused by radiography. However, although Section XI has used
ultrasonic examination for assessment of weld acceptance for
nearly 40 years and both Section III and Section XI have Code
Cases approved or in the approval process (N-569 and N-713)
allowing ultrasonic examination in lieu of radiography, the NRC
has not accepted these Cases despite significant efforts by ASME
and individual Owners to resolve NRC concerns. ASME and the
NRC need to resolve the concerns and allow the use of ultrasonic
examinations in lieu of radiography.
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development and application of risk-informed technology to inservice inspections and repair/replacement activities. Chapters 26, 28,
and 45 of the third edition of the Companion Guide discuss some
of the risk-informed inservice inspection work resulting in Code
Cases N-560, N-577 and N-578, as well as the new NonMandatory Appendix for Risk-Informed Inspection Requirements
for Piping published in the 2005 Addenda of Section XI.
Significant Section XI contributions were also provided in the
area of risk-informed technology work to support the NRC and
industry effort to risk-inform federal regulation 10CFR50. The
NRC and industry worked for several years on an initiative to
develop and implement optional requirements to make changes to
the overall scope of systems, structures and components (SSCs)
covered by 10CFR50 and requiring special treatment. This initiative, called “Option 2,” has been added to the federal regulation as
10CFR50.69 and allows licensees to use commercial standards
and practices for safety-related SSCs that are classified as Low
Safety Significant (LSS). Non-safety related SSCs that are classified as High Safety Significant (HSS) are subject to additional
monitoring, but not to full nuclear treatment as are safety-related
SSCs that are classified as HSS. In support of this initiative,
ASME Section XI developed risk-informed safety classification
and treatment requirements for repair/replacement activities for
passive, pressure-retaining items. The initial efforts by Section XI
in this area resulted in two significant Code Cases: N-660, RiskInformed Safety Classification for Use in Risk-Informed Repair/
Replacement Activities, and Code Case N-662, Alternative
Repair/ Replacement Requirements for Items Classified in
Accordance with Risk-Informed Processes. More detail on these
Cases and on the risk-informed processes and supporting probabilistic risk assessments (PRA) can be found in Chapter 45 of this
third edition of the Companion Guide. However, a few comments
will be made regarding Case N-662.
A consideration of risk-informing the regulations was that
resources would be focused on SSCs that have the highest safety
significance and that reduced special treatment requirements
would be applicable to low safety significant SSCs. Special treatment requirements are current requirements imposed on SSCs
that go beyond industry established requirements for equipment
classified as commercial grade and that provide additional
confidence that the equipment is capable of meeting its functional
requirements under design basis conditions. These special treatment requirements include additional design considerations,
qualifications, change control, documentation, reporting, maintenance, testing, surveillance, and quality assurance requirements
above those that occur with typical industry practices. Some
Section XI repair/replacement activity requirements would be
considered to be special treatment requirements. Code Case
N-662 established the treatment requirements appropriate to items
classified by a risk-informed process. The Case applied full
Section XI requirements to HSS, safety-related items classified as
Risk-Informed Safety Classification 1 (RISC-1). Code Case
N-662 applied a structural integrity treatment requirement for
HSS, non-safety related (RISC-2); LSS, safety-related items originally classified as Code Class 1, 2, and 3 (RISC-3); and for LSS,
non-safety related items originally classified as Code Class 1, 2,
and 3 (RISC-4). The structural integrity treatment requirements of
the Case ensure that an item will meet its functional design
requirements. For LSS Class 1, 2, and 3 items, the structural
integrity requirements represent a reduction in requirements. For
HSS non-class items, the structural integrity treatment requirements represent an increase in requirements beyond how Owners
27.16
REFERENCES
1. ASME Boiler and Pressure Vessel Code Section XI, Division 1, Rules
For Inservice Inspection of Nuclear Power Plant Components; The
American Society of Mechanical Engineers.
2. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 64, No. 183,
Sept. 22, 1999, p. 51372.
3. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 64, No. 183,
Sept. 22, 1999, page 51389.
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PVP-Vol. 383, The American Society of Mechanical Engineers,
1999, pp. 29–38.
5. U.S. NRC Regulatory Guide 1.147, “Inservice Inspection Code Case
Acceptability, ASME Section XI, Division 1,” U.S. GPO,
Washington, DC, Rev. 13 (Reprinted January 2004).
12. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 69, No. 190,
Oct. 1, 2004, pp. 58809, 58820.
6. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 64, No. 183,
Sept. 22, 1999, pp. 51385, 51396.
13. 10CFR50, “Incorporation by Reference of ASME BPV and OM Code
Cases, Final Rule,” US Federal Register, Vol. 68, No.130, July 8,
2003, pp. 40469–40478.
7. Johnson, W. P., Bush, S. H. and MacCary, R. R., “Augmented Scope
of the 1974 ASME Section XI Code Inservice Inspection of Nuclear
Power Plant Components,” Periodic Inspection of Pressure Vessels,
Conference Pub. 8, Inst. of Mechanical Engineers, 1974.
14. 10CFR50, “Industry Codes and Standards, Amended Requirements,
Final Rule,” USA Federal Register, Vol. 67, No. 187, Sept. 26, 2002,
pp. 60526, 60527, 60541.
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4. ASME Boiler and Pressure Vessel Code, Nuclear Component Code
Cases; The American Society of Mechanical Engineers.
15. 10CFR50.55a, “Industry Codes and Standards, Amended
Requirements, Final Rule,” USA Federal Register, Vol. 69, No. 190,
Oct. 1, 2004, pp. 58811, 58812, 58820.
9. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 64, No. 183,
Sept. 22, 1999, p. 51396.
16. U.S. NRC Regulatory Guide 1.193, “ASME Code Cases Not
Approved for Use,” U.S. GPO, Washington, DC, Rev. 2, October
2007.
10. 10CFR50.55a, “Industry Codes and Standards Amended
Requirements, Final Rule,” USA Federal Register, Vol. 64, No. 183,
Sept. 22, 1999, pp. 51372–51373.
17. U.S. NRC Regulatory Guide 1.147, “lnservice Inspection Code Case
Acceptability, ASME Section XI, Division 1,” U.S. GPO,
Washington, DC, Rev. 15 October 2007.
11. Holston, W. C., “Basis for Recent Changes to Construction Code
Reconciliation Requirements, ASME Section XI, Subarticle IWA4200,” Pressure Vessel and Piping Codes and Standards—1999,
18. ASME Operation and Maintenance Code, Code for Operation and
Maintenance of Nuclear Power Plants; The American Society of
Mechanical Engineers.
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8. B&PV Main Committee Minutes, “MC 92-77 (ISI 91-02): Revise
IWA-4120 Exemptions,” Feb. 1992.
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