Interpretations No. 1 to ANSI/ASME 831.8
(This supplement Is not part of ANSIIASME 831.8 or the Addenda It is included for Information only.)
It has been agreed to publish lnterpretations issued by the 831 Committee concerning 831.8 as part
of the subscription service. This supplement includes lnterpretations concerning 831.8 issued between
January 1,1983, and December 31,1983. They have been assigned Interpretation numbers in chronological
order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement will cover inquiries issued over 1 year periods.
These replies are taken verbatim from the original letters, except for a few typographical and editorial
corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these lnterpretations when or i f additional information
is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an
lnterpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement
of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse" any item,
construction, proprietary device, or activity.
831.8 Interpretations No. 1
Interpretation: 1-1
Date Issued:
March 2, 1983
Subject:
Design Based on Inside Diameter
File:
1622
Question: Does ANSIIASME 831.8 recognize and allow design based on inside diameter?
Reply: No.
Interpretation: 1-2
Date Issued:
March 2, 1983
Subject:
Pipe-Type Holders in 844
File:
1630
Question: According to 844.3 of ANSIIASME 831.8, pipe-type holders should have a minimum
clearance from fenced boundaries of site of 25 ft if maximum operating pressure is less than 1000 psig,
and 100 ft if pressure is 1000 psig or more. However, 844.1 of ANSIIASME 831.8 also allows pipe-type
holders to be installed in streets, highways, or in private rights-of-way not under the exclusive control and
use of the operating company if the holders are designed, installed, and tested in accordance with the
provisions of the Code applicable to a pipeline in the same location and operated at the same maximum
pressure. I s it contrary to the requirements of ANSllASME 831.8 if a pipe-type holder, which is to be
installed on site under the exclusive control and use of the operating company, does not have any clearance
limitations from the fenced boundaries, but it is designed, installed, and tested in accordance with the
provisions of the Code applicable to a pipeline installed in the same location and operated at the same
maximum pressure?
Reply: It is not intended that the additional requirements for clearance from fenced boundaries set
out in 844.32(a) and (b) be applied to pipe-type bottle holders meeting the requirements for the class
location in which it is installed.
Interpretation: 1-3
Date Issued:
April 19, 1983
Subject:
Design Safety Factors
File:
1612
Question: If underthickness i s not allowed in pipe fabrication specification, may a safety factor greater
than 0.72 be used in ANSIIASME 831.4 and ANSIIASME 831.8 construction?
Reply: There is no provision in ANSIIASME 831.4 or ANSIIASME 831.8 to permit a design factor
greater than 0.72 to be used in the design of a liquid petroleum pipeline or natural gas pipeline.
3
831.8 InterpretationsNo. 1
Interpretation: 1-4
Date Issued:
October 26,1983
Subject:
Area of Reinforcement for Contoured Integrally Reinforced Fittings
File:
1681
Question: Do the rules for extruded outlets apply to contoured integrally reinforced fittings? If not,
what are the correct equations indicated in ANSIIASME 831.I,B31.2,B31.3,B31.4, and 831.8 to be used
in determining the limits of area reinforcement for contoured integral!^ reinforced branch connecting
fittings (e.g., weldolet) and extruded outlets?
Reply: The contoured integrally reinforced fitting is not an extruded outlet. The equations set forth in
the 831 Codes for determining the reinforcing limits of an extruded outlet do not apply in determining the
reinforcing limits of a contoured integrally reinforced fitting.
The equations set forth in the Code documents for fabricated intersection area reinforcement limits
are the only equations available for contoured integrally reinforced branch connecting fittings.
lnterpretations No. 2 to ANSIIASME B31.8
(This supplement is not part of ANSiIASME 831.8 or the Addenda. i t is included for information only.)
It has been agreed to publish lnterpretations issued by the 831 Committee concerning 831.8 as part of
the subscription service. This supplement includes lnterpretations concerning 831.8 issued between January 1, 1984, and December 31, 1984. They have been assigned lnterpretation numbers in chronological
order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement
will cover inquiries issued over 1 year periods.
These replies are taken verbatim from the original letters, except for a few typographical and editorial
corrections made for the purpose of improved clarity.
ASME procedures provide for rensideration of these Interpretationswhen or if additional information i s
available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an Interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of
Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse" any item, construction, proprietary device, or activity.
B3 1.8 Interpretations No. 2
Interpretation:
2-1
Date Issued:
November 16,1984
Subject:
Hoop Stresses in 841.32
File:
831-84-006
Question: To determine whether hoop stresses exceed 30% of the SMYS of pipe in 841.32 of ANSI/
ASME 831.8, shall the 0.30 factor be applied to the entire hoop stress formula given in 841.1 1(a)?
Reply: No. The 0.30 factor shall be applied to 2StlD. Factors F, E, and T are not to be used in this
Case.
lnterpretations NO.3 to ANSllASME 831.8
(Thhrupplement is not pert of ANSllASME 831.8 or the Addenda. It is included for information only.)
It has been agreed to publish lnterpretations issued by the 831 Committee concerning 831.8 as part of
the subscription service. This supplement includes lnterpretationsconcerning B31.8 issued between January
1, 1985, and June 30, 1985. They have been assigned Interpretation numbers in chronological order.
Each lnterpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation.
Subsequent revisions to the Code may have suspended the reply. Future versions of this supplement will
cover inquiries issued over 1 year periods.
These replies are taken verbatim from the original letters, except for a few typographical and editorial
corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these lnterpretations when or if additional information
is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an
lnterpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement
of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse" any item,
construction, proprietary device, or activity.
831.8 InterpretationsNo. 3
Interpretation: 3-1
Subject:
845.243, Overpressure Protection for Fuel Gas Piping
Date Issued: March 4, 1985
File:
B31-84-010
Question: At a power plant, high pressure natural gas is delivered to a meter set assembly which
includes two regulating valves in series that reduce the natural gas pressure to a level suitable for firing
the boiler. Do these two regulating valves in series provide the overpressure protection required by
the ANSIIASME B31.T Code?
Reply: As stated in Para. 100.1.2(c), the scope of the ANSIIASME 831.1 Code includes only the
piping downstream from the meter set assembly. The meter set assembly and the piping upstream are
included in the scope of the ANSVASME 831.8 Code. Paragraph 845.243 of the 831.8 Code describes
three suitable methods which may be used to regulate and limit the maximum safe value of the
pressure delivered to the customer. The regulating valves, as described in this Inquiry, should be
acceptable if they conform to one of the methods described in Para. 845.243.
Interpretation: 3-2
Subject:
825.2 and 825.3, Thickness to be Used to Determine Stress Relieving
Date Issued: April 15, 1985
File:
83 1-84-026
Question (1): A section of pipe having a wall thickness of less than 1: in. is to be welded to a
fabricated tee having a nominal wall thickness greater than 1: in. which has been tapered to match
the wall thickness of the pipe. Is stress relieving required per 825.2 and 825.3 of ANSIIASME 831.81
Reply (11: Assuming the tee is manufactured under the appropriate MSS specification, the taper
in the wall thickness of the tee is made in accordance with Appendix I of B31.8 and appropriate
qualified welding procedures are employed, stress relieving is not required.
Question (2): At what specific location is the wall thickness to be measured when determining
the need for stress relieving as required in 825.2 and 825.3 of ANSIIASME B31.8?
Reply (2): The determining wall thickness is the maximum wall thickness of the pipe or fitting in
the heat-affected zone of the weld joint.
831.8 Interpretations No. 3
Interpretation: 3-3
Subject:
822.1 (b) and Appendix I, Fig. 15, Acceptable End Preparations
Date Issued April 15, 1985
File:
831-84-036
Question: Does the joining of two equal strength pieces of pipe with unequal wall thickness,
with the thicker piece being counterbored, meet the requirements of Fig. 15 of ANSIIASME B31.8?
Reply: The weld configuration is one of unequal wall thickness and equal strength as depicted
in Fig. 15(b), with asterisk footnote, or with equal walls as in Fig. 14.
Interpretation: 3 4
Subject:
849.222, Installation of Gas Line Under Buildings
Date Issued: June 5, 1985
File:
831-85-007
Question: Gas piping is installed beneath a building floor. Does 849.222(b) require that the
portion of the piping under the building, but not necessarily the section outside the building, be
encased in a gas tight conduit?
Reply: Yes.
Interpretations No.
It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8 as
part of the update service. This supplement includes interpretations concerning 831.8 issued between
January 1, 1986, and December 3 1, 1986. They have been assigned interpretation numbers in chronological orde;. Each interpretation applies to the latest Edition or Addenda at the time of issuance of the
interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have
superseded the reply. The interpretations are not part of the Code or the Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or sukommittee. As stated
in the Statement of Policy in the Code documents, ASME does not "approve," "certify," "rate," or
"endorse" any item, construction, proprietary device, or activity.
831.8 Interpretations No. 4
Interpretation: 4-1
Subject:
Flexibility Factor and Stress Intensification Factor Tables
Date Issued:
October 17, 1986
File:
83 1-85-030
Question (1): What is the difference between a "welding tee per ANSl 816.9" and an "extruded
welding tee" as stated in Appendix D, Table D-1, of ANSIIASME 831.3 and Appendix E, Table E-1,
of ANSIJASME 831.8?
Reply (1): A "welding tee per ANSl 816.9" complies with all requirements of ANSl 816.9. An
"extruded welding tee" complies with the requirements of 304.3 of ANSIIASME 831.3 or 831.41 and
831.6 of ANSIIASME 831.8.
Question ( 2 ) : Is the difference related to ANSl 816.9 dimensions as defined by ANSIJASME 831.3
and ANSIIASME 83 1.8?
Reply ( 2 ) : No.
Question (3): Is the difference related to manufacturing?
Reply (3):
ANSI
816.9 does not specify manufacturing methods.
Question (4): When a "welding tee per ANSl 816.9" does not meet the radius and thickness limits
specified in Appendix D, Table D-1, of ANSIJASME 831.3 or Appendix E, Table E-1, of ANSIIASME
831.8, is it permissible to use the flexibility characteristic h for an "extruded welding tee" provided
r, 2 Db and T, < 1.ST?
Reply (4): Yes, provided the tee is formed by an extrusion process; otherwise it is the responsibility
of the designer to determine the proper flexibility characteristic.
831 .€I
Interpretations No. 4
Interpretation: 4-2
Subject:
826.2, NDE of Gas Compression Equipment
Date Issued:
December 1, 1986
File:
B3 1-85-023
Question (1): According to 8?6.2, what percentage of the butt welds in new packaged gas
equipment shall be examined for use in Class 3 locations?
Reply (1): 100°/o if practical, but no less than 90% [see 826.2(b)(5)].
Question (2): If a gas compression package is designed and tested for use in a Class 3 location
and is later relocated to a compressor station, what additional requirements apply?
Reply (2): None.
Question (3): A new section of piping is added to existing gys compression equipment. What
percentage of the new welding is required to be examined?
I
I
Reply (3): See Reply (11.
Question (4): If new piping is added to existing gas compression equipment, is it required that any
of the existing welding be examined?
Reply (4): No, if it met the conditions of 826.2(b)(5).
Interpretations No.
Replies to Technical Inquiries
February 1, 1987, Through December 31, 1988
It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8 as
part of the update sewice to the Code. The interpretations have been assigned interpretation numbers
in chronological order. Each interpretation applies to the latest Edition or Addenda at the time of
issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to
the Code may have superseded the reply. The interpretations are not part of the Code or the
Addcmk.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated
in the Statement of Policy in the Code documents, ASME does not "approve," "certify," "rate," or
"endorse" any item, construction, proprietary device, or activity.
831.8 Interpretations No. 5
Interpretation: 5-1
Subject:
ANSIIASME 831.8, 845.41 I, Overpressure of Corroded Piping Systems
Date Issued:
February 5, 1987
File:
83 1-86-038
Question: When a reduced Maximum Allowable Operating Pressure (MAOP) of a corroded
piping system has been set equal to the safe maximum pressure determined in accordance with the
methods of Appendix L, may the provisions of 845.41 1 of ANSIIASME 831.8 be applied, where the
piping system pressure relief or pressure limiting station(s) prevent the pressure from exceeding the
reduced MAOP plus 1P/o, or prevent the pressure from producing a nominal hoop stress greater than
7S0/b of the specified minimum yield strength, whichever is lower?
Reply: The provisions of 845.41 1 of ANSIIASME B31.8 may be applied because Appendix L
provides a P' which may be less than the original design pressure or established MAOP. The P' would
then become the new MAOP for purposes of determining the not-to-exceed pressure in 845.41 1. This
not-to-exceed pressure is the lower of 1100/0 of P' or the pressure which produces a hoop stress of
75% of SMYS based on the original nominal wall thickness.
831.8 Interpretations No. 5
5-2, 5-3
Interptation: 5-2
Subject:
ANSIIASME 83 1.8, 841.I
23 and 854.1(c), Pipeline Reclassification
Date Issued:
February 5, 1987
File:
83 1-86-039
Question (1): Why do the requirements in 841.I23 of ANSIIASME 831.8 call for all pipeline
bridges in Class 1 areas to be of Type 8 construction?
Reply (1): See 841.13(a) .of ANSIIASME 831.8.
Question (2): Where changes in population index imply that road or river crossings would require
to be classified with a higher construction type, would it be necessary to reduce the maximum
permissible operating pressure or replace crossings with increased wall thickness, or would it be
sufficient to retest the section hydrostatically to prove the integrity?
Reply (2): Class locations and population density indexes are defined in 840.2. Subparagraph
854.1 (c) indicates what items to study when the population density index increases. Paragraph 854.2
fully covers the alternatives available with respect to retesting, lowering the MAOP, or replacing pipe
as a result of a population density index increase.
Question (3): In 854.1 (c) the Code lists five areas to be considered in a study to reclassify a line.
Is the Committee able to advise on more specific points or particular areas that should be reviewed
or inspected, and the most critical points that require careful consideration when embarking on a
reclassification study?
Reply (3): As a Code writing body, the 831.8 Section Committee is limited to interpretingthe Code
and cannot give advice on specific applications.
Interpretation: 5-3
Subject:
ANSIIASME 831.8, 846.1 1(dl and 846.21(c), Valves at Offshore Platforms
Date Issued:
February 12, 1988
Question (1): Do the requirements of ANSIIASME 831.8 specify a location for valves that are
required to shut off the flow of gas to an offshore platform in an emergency?
Reply (11: No, only that valves or other components shall be provided to shut off the flow of gas
to the offshore platform. See 846.1 1(d).
Question (2): Do the requirements of ANSIIASME 831.8 specify a location for blowdown valves?
Reply (2): No, only that each section of pipeline between block valves can be blown down, and
blowdown piping shall be sized such that under emergency conditions the section of line can be blown
down as rapidly as is practical. See 846.21(c).
031.8 lnteqmtations No. 5
Subject:
ANSIIASME 831.8, 841.1 1(a), Steel Pipe Design Formula
File:
831-87-030
Date Issued:
February 12, 1988
Question: When determining design pressurefor okler pipelines in place and where pipe records
are minimal, wouldn't the 24,000 psi valve be a sufficient downgradefor both the E and S factors found
in design formula 841.1 1(a) of ANSIIASME 831.81
Reply: No. See 811.253.
Subject:
ANSIIASME 831.8, 833.4, Stress Calculations
File:
83 1-86-03 7
Date Issued:
April 14, 1988
Question (11: Paragraph 833.4 of ANSIIASME 831.8 states that "The sum of 833.4(b) and (c) shall
not exceed 75% of the allowable stress in the hot condition. . An interpretationof this requirement
is that (b) (c) shall not exceed 54% of SMYS (75% of 72% for design factor = 0.72 locations). Does
this reflect the intent of this section?
+
. ."
Reply (1): No. The sum of (b)+(c) cannot exceed 75% of SMYS. The longitudinal pressure stress
(b) is limited by 841.1 1, SFT.
Question (2): Subparagraph 833.4 (c) of ANSIIASME 031.8 includes "wind" as an occasional
load component. Stresses resulting from wind induced vortex shedding on above ground pipelines has
always been considered a fatigue load. This fatigue load is evaluated using fatigue load criteria, and
not as an occasional wind load to be included under the requirements of 833.4(c). Is this correct?
Reply (2): Yes.
831.8 Interpretations No. 5
Interpretation: 5-6
Subject:
ANSIIASME 031.8, 833, Stress Calculations
File:
03 1-87-016
Date Issued:
April 19, 1988
Question (1): In evaluating expansion stress under ANSIIASME 831.8, should both the thermal
and pressure effects be considered? If not, which of the two and why?
Reply (1): Yes, but not together. Thermal effects should be considered in 833.3 while pressure
effects should be considered in 833.4(b).
Question (2): Is axial force in a pipeline a component of the longitudinal pressure stress?
Reply (2): No. The longitudinal force resultingfrom pressure stress is one component of axial force
in a pipeline.
Question (3): In 833.4 of ANSIIASME 031.8, is it correct to assume that the intent is that the
longitudinal pressure stress considers only the effects of pressure and that the longitudinalbending stress
considers external loads, both sustained and occasional? If not, what is the intent?
Reply (3): Yes. Bending stresses due to internal pressure should be considered in the longitudinal
pressure stress [833.4(b)] and the external loads, sustained or occasional, should be considered in the
longitudinal bending stress [833.4(c)], which are primary and not secondary.
831.8 Interpretations No. 5
Interpretation: 5-7
Subject:
ANSIIASME 031.8, 833.4, Stress Due to Displacement
File:
B3 1-86-030
Date Issued:
August 11, 1988
Question (11: A piping system is being designed from one offshore platform to another offshore
platform via a connecting bridge as per ANSIIASME 031.8 (classification of steel pipe construction
Type C).Platforms are subject to severe deflections under extreme environmental conditions and their
differential deflection is severe. Is this deflection effect on piping a part of the loads discussed under
833.4(c) (wind, etc.)?
Reply (11: No. Subparagraph 833.4(c) is intended to limit the sum of longitudinal bending stresses
resulting from externally applied "primary" loadings, from whatever source. It is not intended to apply
to stresses resulting from self-limiting, secondary displacement strains. Wind and wave action that acts
on the pipe itself is an externally applied "primary" loading and must be included in 833.4(c). However,
wind and wave action that is applied to an offshore platform causes a predictable displacement of the
platform which is limited by the design of the platform. Movement of the platform imposes displacements on the piping restraints and supports which is similar to thermal effects. These displacements
must be included with thermal effects in flexibility and expansion analysis.
Question (2): If so, can the allowable stress for 833.4(b) and (c) be increased to a higher value
as per ANSIIASME 031.4?
Reply (2): No. There are no increases permitted in the allowable stresses specified in 833.3 and
833.4. ASMEIANSI 031.3 and 031.4 have no bearing on 833 of ANSIIASME 031.8.
Question (3): As per ASMEIANSI 031.3, the deflection effects are to be considered together with
thermal effects for displacement stress range computation only. Does this apply to ANSIIASME 031.8
stress range computation also?
Reply (3): Yes. Secondary stresses resulting from externally imposed fixed displacements should
be included with the calculation of expansion stresses covered in 833.3 and 833.4(a).
Question (4): Occasionally some clients interpret that the expansion stress (secondary stress) as
per ANSIIASME 031.8 for construction type C shall not exceed 0.5s. Does the allowable expansion
stress require adjustment based on construction type?
Reply (4): No.
Question (5): Are there any adjustments to the allowable limits for the total longitudinal stress
computed per 833.4(a), (b), and (c) to reflect the construction type?
Reply (5): The longitudinal pressure stress calculated in 833.4(b) must be adjusted for the construction type design factor.
lnterpretations No. 6
Replies to Technical Inquiries
April 1, 1989, Through August 31, 1989
It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8 as
part of the update service to the Code. The interpretations have been assigned interpretation numbers
in chronological order. Each interpretation applies to the latest Edition or Addenda at the time of
issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to
the Code may have superseded the reply. The interpretations are not part of the Code or the
Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated
in the Statement of Policy in the Code documents, ASME does not "approve," "certify," "rate," or
"endorse" any item, construction, proprietary device, or activity.
831.8 Interpretations No. 6
Interpretation: 6-1
Subject:
ANSIIASME B31.8, Paras. 81 1.253(b) and (g), Qualification of Steel Pipe
Date Issued:
April 5, 1989
File:
83 1-88-026
Question: For qualification of used steel pipe or unidentified new steel pipe for use at stress levels
above 6000 psi, ANSIIASME 831.8 specifies the following requirements (in addition to others):
(i)flattening test for pipes larger than NPS 2 [reference para. 81 1.253 (b)];
(ii) yield-tensile ratio less than or equal to 0.85 [reference para. 81 1.253 (g)].
Can it be interpretedfrom the above that for new pipes ordered as per a 'Code' approved standard
(e.g. API 5L), the above requirements should be specified as additional requirements, in the event they
are not mandatory requirements, for a particular type or grade of steel pipe?
Reply: No.
Interpretation: 6-2
Subject:
ANSIIASME B31.8, Requirements for Compressed Air Piping Systems
Date Issued:
June 22, 1989
File:
83 1-88-031
Question: Does ANSIIASME B31.8 cover piping systems for compressed air systems, such as
those used in industrial automation, robotics, and air driven tools?
Reply: No. You are directed to the Scope sections of B31.I(para. 100.1.3), B31.3 [para.
300.1 .l(b)], and 631.9 (para. 923.3.2) which may be suitable for your application. You may wish to
also review the requirements of Chapter VII in B31.3 on nonmetallic pipe.
831.8 Interpretations No. 6
Interpretation: 6-3
Subject:
ANSIIASME 831.8, Para. 802.1 3(f), Design of Flow Lines
Date Issued:
August 17, 1989
File:
83 1-89-002
Question (1): ANSIIASME 831.8's para. 802.1 3(0 states that this Code does not apply to flow
lines between wellheads and traps or separators. Many flow lines in the oil field have been designed
1(a). What is the intent of this exclusion?
using the design formula from this Code under para. 841 .I
Reply (1): The original intent of excluding flow lines from 831.8 is unknown; however, the intent
of 63 1.8 is to cover field gathering pipelines, transmission lines, and distribution systems. See Fig. 18,
Appendix I.
Question (2): If 831.8 is not the appropriate Code for flow line design, what is?
Reply (2): See 831 Code Case 137, Piping Not Covered by Any ANSIIASME 831 Section, for
guidance.
Interpretation: 6-4
Subject:
ANSIIASME 831.8, Paras. 802.1 3(g) and 803.261, Exclusion from ScopeInstrument Piping
Date Issued:
August 2 1, 1989
File:
83 1-88-028E
Question: Does ANSIIASME 831.8 require that the pressure-containing portion of an in-line
sensing device be designed, fabricated, examined, and tested in accordance with the rules of
ANSIIASME 831.81
Reply: Yes.
631.8 Interpretations No. 6
Interpretation: 6-5
Subject:
ANSIIASME 831.8, Para. 840.l(a), Maximum Allowable Stress for Buried Pipe
Subject to Ground Movement
Date Issued:
August 2 1, 1989
File:
Question: Under the requirements of ANSIIASME 831.8, what is the maximum allowable stress
for buried gas pipelines subject to movement at active ground faults?
Reply: The 831.8 Code does not specifically indicate the maximum allowable stresses in buried
gas pipelines resulting from catastrophic events such as movement at fault crossings. See para. 840.1 (a).
Interpretation: 6-6
Subject:
ANSI IASME B3 1.8, Para. 843.5 11, Limits of Compressor Station Piping
Date Issued:
August 22, 1989
File:
B3 1-89-003
Question (1): Under the requirements of ANSIIASME B31.8, what is the basis of using Type C
construction for compressor stations?
Reply (11: Table 841.1 5A.
Question (2): Is Type C construction related to reciprocating compressor stations?
Reply (2): Type C construction applies to all types of compressor stations including reciprocating.
Question (3): What is the breakpoint for Type C construction?
Reply (3): The station suction and discharge valves if the station is located in Location Classes 1,
2; or 3. See para. 843.5 11.
Question (4): Under the requirements of ANSIIASME 831.8 does compressor station piping, Type
C, apply from the suction valve to the discharge valve?
Reply (4): Type C construction applies from the station (not the compressor unit) suction valve
to the station (not the compressor unit) discharge valve. See para. 843.51 1.
831.8 Interpretations No. 6
6-7
,--.
' \
Interpretation: 6-7
Subject:
ANSIIASME 831.8, Para. 843.51 1 and Table 841.1SA, Limits of Compressor
Station Piping
Date Issued:
August 23, 1989
File:
B3 1-89-015
Question (11: Under the requirements of ANSIIASME 831.8, Para. 843.51 1 and Table 841.15A,
is Type C construction only limited up to the discharge valve of the individual compressor units, and
Type 8 construction limited to the combined suction and discharge line of a compressor station?
Reply (11: No. Type C construction applies from the station (not the compressor unit) suction valve
to the station (not the compressor unit) discharge valve.
Question (2): If new piping i s added upstream of the discharge fire gate, of an existing compressor
station for incorporation of gas cooling equipment, is such piping required to be of Type C construction?
Reply (2): Yes.
Question (3): Do the requirements of Para. 843.51 1 and Table 841.1 5A limit Type C construction
to compressor stations having reciprocating compressor units, or do they include compressor stations
having centrifugal compressors as well?
Reply (3): Type C construction applies to all types of compressor stations including reciprocating
and centrifugal.
INTERPRETATIONS NO. 7
Replies to Technical Inquiries
September 1, 1989, Through August 31, 1990
It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8
as part of the update service to the Code. The interpretations have been assigned interpretation
numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda
at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent
revisions to the Code may have superseded the reply. The interpretationsare not part of the Code
or the Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information is available which the inquirer believes might affect the interpretation. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As
stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
831.8 lnterpretations No.7
Interpretation: 7-1
Subject:
Hydrotest Preparation
Date Issued:
June, 12, 1987
File:
831-86-033
Question: May all joints, including welds, used in piping systems covered by ANSVASME B31.I,
ANSIIASME 831.3, ANSIIASME 831.4, ANSIIASME 831.8, ANSVASME B31.9, and ANSIIASME 831.I
1
be primed and painted prior to hydrotest?
Reply: Yes.
Note: This interpretationwas inadvertently omitted from Interpretations No. 5, which includes
interpretations issued from February 1, 1987, through December 31, 1988.
Interpretation: 7-2
Subject:
1(a) and 841.I
21(f), Mimimum Yield Strength
Paras. 841.I
Date Issued:
February 26, 1990
File:
831-89-022
Question: Is it permissible under the requirements of para. 841.I21 (f) in ANSIIASME 831.8 to
use an actual yield strength value that is less but not greater than the specified minimum yield
strength as stipulated in the specification?
Reply: Yes.
831.8 Interpretations No. 7
Interpretation: 7-3
Subject:
Para. 823.22, Welder Qualification Test
Date Issued:
February 26, 1990
File:
B31-89-011
Question (1): Under the requirements of ANSIIASME 831.8, para. 823.22, is it permissible to
test the welder to API 1104 but ignore the results of tensile and nick-break tests?
Reply (1): No.
Question (2): Under the same paragraph in Question (I), is it permissible to test the welder to
API 1104 but using only six bend tests instead of two tensile, two nick, and two root bend tests?
Reply (2): No.
Question (3): Under the same paragraph in Question (I), is it permissible to test the welder to
API 1104 but use Appendix G of ANSIIASME B31.8 to test the straps?
Reply (3): No.
Question (4): If Reply (3) is no, are there some other requirements than those questioned in
(11, (21, and (3)?
Reply (4): Yes. Test the welder to the provisions of API 1104 including the guided bend tests.
Interpretation: 7-4
Subject:
Para. 843.443, Setting of Pressure Relief Valves
Date Issued:
March 7, 1990
File:
83149-014
Question: Under the requirements of ASME B31.8, para. 843.443, can a safety relief valve be
set at any pressure between the maximum allowable operating pressure (MA0P)and 110% of the
maximum allowable operating pressure for compressor station piping?
Reply: Yes. The safety relief valve can be set at any point which will assure the operating pressure
of the compressor and discharge piping will not exceed the maximum allowable operating pressure
by more than 10%.
INTERPRETATIONS NO. 8
Replies to Technical Inquiries
September 1, 1990, Through August 31, 1991
Interpretations 8-1 Through 8-8
It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8
as part of the update service to the Code. The interpretations have been assigned interpretation
numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda
at the time of issuance of the interpretation or the Edition or Addenda stated in the reply.
Subsequent revisions to the Code may have superseded the reply. The interpretations are not part
of the Code or the Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information is available which the inquirer believes mlght affect the interpretation. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As
stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
831.8 Interpretations No. 8
Interpretation: 8-1
Subject:
ASME B31.8, Para. 802, Applicability to Bypass Lines
Date Issued:
November 21, 1990
File:
B31-90-022
Question (1): Does ASME B31.8 apply to bypass lines around pipeline block valves?
Reply (1): Yes.
Question (2): Does ASME B31.8 apply to bypass lines which operate at temperatures as low
as
- 46"C?
Reply (2): No. ASME B31.8 is not applicable to piping with metal temperatures below -20°F.
[See para. 802.13(b).]
Interpretation: 8-2
)
Subject:
ASME B31.8, Para. 842.31, Plastic Pipe and Tubing Design Formula
Date Issued:
March 4, 1991
File:
B31-90-054
Question: Based on the attached derivation, should not the design formula for plastic pipe and
tubing in para. 842.31 be
Reply: No. The formula found in the Code is based on an International Standards Organization
(ISO) equation. See ASTM D 2513.
Interpretation: 8-3
b
Subject:
Design of Scraper Traps
Date Issued:
April 9, 1991
File:
B31-90-039
Question (1): Can a barrel of a scrapper trap be designed in accordance with ASME B31.8?
Reply (1): Yes.
Question (2): Can Appendix 24, ASME Section VIII, Division 1 be applied to the design for
the end closure, when the clamp type connection is applied to the end closure of the scraper trap?
Reply (2): Yes.
831.8 Interpretations No. 8
Interpretation: 8-4
Subject:
ASME B31.8-1989 Edition, Paras. 826.1 and 841.322(c), Inspection of Welds and
Testing After Construction
Date Issued:
April 9, 1991
File:
B31-90-068
Question (1): Does para. 826.1 exempt a piping system intended to operate at 1440 psig with
material having a specified minimum yield strength of 35,000 psi from radiographic or other NDE?
Reply (1): Paragraph 826.1 would apply only if the hoop stress S, is less than 20% of the SMYS;
otherwise, para. 826.2 would apply.
Question (2): Under para. 841.322(c), would pipelines and mains in Location Class 2 require
testing at 1.25 times MOP regardless of hoop stress?
Reply (2): Yes.
Interpretation: 8-5
Subject:
ASME B31.8-1989 Edition, Para. 833.2 and Appendix E, Stress Intersification Factor
Date Issued:
April 9, 1991
File:
B31-91-003
Question: When determining the expansion stress as defined by para. 833.2, may the in-plane
ii and out-plane i, intensification factors be used rather than the more conservative stress intensification factor i?
Reply: Yes. See Notes (1) and (2) of Table E-1.
Interpretation: 8-6
Subject:
ASME B31.8-1989 Edition, Para. 831.31(b), Use of Buttwelding Fittings With Nonstandard Dimensions
Date Issued:
June 23, 1991
File:
B31-91-014
Question: Do reducers or reducing outlet tees that have nonstandard dimensions and are in
"partial compliance" with ANSI B16.9 or MSS SP-75 fulfill the requirements of ASME B31.8?
Reply: Yes, provided the requirements of paras. 801.2 and 831.32 are met.
831.8 Interpretations No. 8
Interpretation: 8-7
Subject:
Paragraph 840.2(b) and Tables 841.114A and B, Definition of Location Class 1,
Division 1
Date Issued:
June 23, 1991
File:
B31-91-018
Question: Table 841.114A, Basic Design Factor F, identifies a Location Class 1, Division 1, and
an associated design factor 0.80. Table 841.114B, Design Factors for Steel Pipe Construction, lists
the type of facility and the associated location class for pipelines, etc. Paragraph 840.2(b) is referenced.
I have Addenda through January 15, 1991 for the 1989 Edition. However, I cannot find any
reference wherein Division 1 and Division 2 are differently defined for Location Class 1. Could you
please point out the proper paragraph. I would appreciate it very much.
Reply: Paragraph 840.2(b) is being revised to include definitions of Location Class 1 Division
1 and Location Class 1 Division 2. The proposed definitions are presently going through the ASME
approval process before publication.
Interpretation: 8-8
1
Subject:
Welding Terminology
Date Issued:
June 24, 1991
File:
B31-91-009
Question (1): What is meant by "longitudinal joint factor E" of Table 841.1B?
Reply (1): In ASME B31.8a-1990 Addenda, the longitudinal joint rating factor is contained in
Table 841.115A. The longitudinal joint factor is the term E in the design formula of para. 841.11(a)
used to compensate for the characteristic strength of a weld seam in a pipe.
Question (2): What is the definition of "electric arc welding"?
i
Reply (2): Definitions of welding processes are contained in para. 804.243. The term "electric
arc welding" is not defined. Both electric-fusion-welded pipe [para. 804.243(c)] and double submerged-arc-welded pipe [para. 804.243(e)] are produced using electric arc welding in which coalescence is produced by heating with a electric arc(s) between the metal electrode(s) and the work.
Question (3): What is meant by "joint efficiency"?
Reply (3): Joint efficiency is not defined even though para. 817.13(d) is titled "Joint Efficiency."
However, the terms "joint efficiency" and "longitudinal joint factor" mean the same thing.
INTERPRETATIONS NO, 9
Replies to Technical Inquiries
September 1, 1991, Through August 31, 1992
Interpretation 9-1
It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8
as part of the update service to the Code. The interpretations have been assigned interpretation
numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda
at the time of issuance of the interpretation or the Edition or Addenda stated in the reply.
Subsequent revisions to the Code may have superseded the reply. The interpretations are not part
of the Code or the Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information is available which the inquirer believes might affect the interpretation. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As
stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
831.8 Interpretations No. 9
Interpretation: 9-1
Subject:
Paragraph 841.231, Wrinkle Bends
Date Issued:
August 31, 1992
File:
B31-92-009
Question (1): First of all, please acknowledge if it is correct that ASME can give answers to
any question on ANSI B31.8 since ANSI B31.8 has been developed by one of ASME's committees.
Reply (1): This interpretation originates from the B31.8 committee directly and is in full accordance with the ASME policy on inquiries.
Question (2): ANSI B31.8, para. 841.231(a), states "all bends shall be free from buckling ..."
Please advise us of the definition of buckling and how buckling is different from wrinkle bends in
para. 841.231(f).
Reply (2): There is no definition of buckling in B31.8. Paragraph 841.231(a) is intended to
mean bends other than wrinkle bends.
Question (3): ANSI B31.8, para. 841.231(f) states: "Wrinkle bends shall be permitted only on
systems operating at less than 30% of the specified minimum yield strength. When wrinkle bends
are made in welded pipe, the longitudinal weld shall be located as nearly to 90 deg. with the top of
the wrinkle as conditions will permit. Wrinkle bends with sharp kinks shall not be permitted. Wrinkles shall have a spacing not less than the distance equal to the diameter of the pipe measured
along the crotch. On pipe NPS 16 and larger, the wrinkle shall not produce an angle of more than
1%deg. per wrinkle."
(a) What is the definition of "wrinkle bends"? Is it wrinkles in bends which happen to exist
unavoidably on intrados of the bends during the bending process, or is it one kind of bending method
such as hot bend and cold bend?
(b) What is the definition of "crotch"? Could you explain how to measure "the diameter of
the pipe measured along the crotch" by a drawing?
(c) It seems to be practically difficult to measure an angle of wrinkle. Could you recommend
the method of measuring the angle of a wrinkle?
(d) On pipe NPS 16 and larger, there is a permitted tolerance for the angle per wrinkle. How
is it in the case of pipe under NPS 16?
(e) Would you acknowledge the following specific case? "Pipe bend of material API 5L X46
seamless pipe can be permitted on systems operating at 1,250 psi even though it has wrinkles on
intrados, if wrinkles meet the tolerances of spacing and angle specified in para. 841.231(f)." We
believe the above is correct, as 1,250 psi is less than 30% of the minimum yield strength of X46
pipe (1,250 psi < 46,000 psi x 30% = 13,800 psi).
Reply (3):
(a) A wrinkle bend as used in B31.8 is a bend in which the wrinkles are produced intentionally
to secure a shorter radius bend. The use of such bends is restricted to systems operating at less than
30% of SMYS. It is not related to the method of bending.
(b) The term crotch in para. 841.231 refers to the line along the inner curvature of a pipe
bend.
(c) The geometry of the individual wrinkle is not specifically measured. The language refers
to the total angle of the bend divided by the number of visible wrinkles, i.e., the change in bend
angle per wrinkle.
9- 1
831.8 Interpretations No. 9
(d) Paragraph 841.231 does not include a limit for the angle of a bend containing wrinkles
in pipe smaller than NPS 16.
(e) The example stated is incorrect. The internal pressure has been confused with the specified minimum yield strength of the bend material. The maximum allowable operating pressure of
the example bend depends on its thickness and is 30% of the pressure calculated according to the
equation in para. 841.11.
Question (4): We understand that there is a separate standard ES-24 issued by PFI (Pipe
Fabrication Institute) which specifies pipe bending methods, tolerances, processes, and material
requirements. Please advise whether PFI Standard ES-24, para. 6.2, has any relation with ANSI
B31.8, para. 841.231(f).
Reply (4): The PFI Standard ES-24 is not under the jurisdiction of ASME and we are unable
to comment on how it is to be applied.
Question (5): We would like to know whether there is any charge for your service.
Reply (5): There is'no charge for the B31.8 Section Committee to provide interpretations of
the B31.8 Code.
,L
INTERPRETATIONS NO. 10
Replies to Technical Inquiries
September 1, 1992, Through August 31, 1993
Interpretations 10-1 Through 10-11
It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8
as part of the update service to the Code. The interpretations have been assigned interpretation
numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda
at the time of issuance of the interpretation or the Edition or Addenda stated in the reply.
Subsequent revisions to the Code may have superseded the reply. The interpretations are not part
of the Code or the Addenda.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for the purpose of improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information is available which the inquirer believes might affect the interpretation. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As
stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
B31.8 Interpretations No. 10
Interpretation: 10-1
Subject:
ASME B31G-1991
Date Issued:
June 3, 1993
File:
B31-92-052
Question: Does ASME B31G-1991 Manual for Determining the Remaining Strength of Corroded Pipelines cover all of the ASME B31 Codes for Pressure Piping?
Reply: No. ASME B31G-1991 covers only ASME B31.4 Liquid Transportation Systems for
Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols; ASME B31.8 Gas Transmission and Distribution Piping %stems; and ASME B31.11 Slurry Transportation Piping Systems.
Interpretation: 10-2
Subject:
ASME B31.8 1989 Edition, Duplex Stainless Steels
Date Issued:
June 7, 1993
File:
B31-91-026
Question: Is the use of duplex stainless steel, such as ASTM A 790 Grade S31803, permitted
by the rules of ASME B31.8?
Reply: No.
Interpretation: 10-3
Subject:
ASME B31.8-1989 Edition, Para. 831.41(c) and Fig. F5, Reinforcement of Welded
Branch Connections
Date Issued:
June 7, 1993
File:
B31-92-011
Question (1): Is there an inconsistency between the definition of d as specified in ASME B31.81989 Edition, para. 831.41(c) and ASME B31.8-1989 Edition, Fig. F5?
Reply (1): Yes. The correct definition for d is "the length of the finished opening in the header
wall measured parallel to the axis of the run" as shown in para. 831.41(c). The definition of d in
Fig. F5 is being corrected.
Question (2): Does ASME B31.8-1989 Edition include branch connections by insertion?
Reply (2): No.
831.8 Interpretations No. 10
Interpretation: 104
Subject:
ASME B31.8-1989 Edition, Para. 840.2, Location Class 4
Date Issued:
June 7, 1993
File:
B31-92-012, B31-92-044, B31-92-045, B31-92-046
Question: Does ASME B31.8-1989 Edition provide a numerical index for the description of
"multistory buildings are prevalent" and "traffic is heavy or densey7as stated in ASME B31.8-1989
Edition, para. 840.2?
Reply: No.
Interpretation: 10-5
Subject:
ASME B31.8-1989 Edition, Paras. 840.2 and 845.4
Date Issued:
June 7, 1993
File:
B31-92-053
Question (1): Does ASME B31.8-1989 Edition state whether to use Division 1 or Division 2 in
gas pipelines regions classified as Location Class l ?
Reply (1): No. The choice is made by the operating company.
Question (2): Does ASME B31.8-1989 Edition address the condition prescribed in para. 845.411
in sections of pipeline classified as Division 1 assuming an internal pressure that produces a hoop
stress equivalent to 80% of the specified minimum yield strength?
Reply (2): No.
831.8 Interpretations No. 10
Interpretation: 10-6
Subject:
ASME B31.8-1989 Edition, Platform Piping
Date Issued:
July 7, 1993
File:
B31-92-054
Question (1): From two wellhead platforms, a 6 in. test line from a test manifold and an 18 in.
production line from a production manifold transport gas to their respective separators on a productionlutility platform. These lines are installed on connecting bridges via a support platform. Is
the ASME B31.8-1989 Edition appropriate for the design of these lines crossing the connecting
bridges?
Reply (1): No. Per para. 802.13(f), the Code does not apply to flow lines between wellhead and
separator.
Question (2): May the ASME B31.8-1989 Edition be extended to design temperature below
-20°F [para. 802.13(b)J once the impact tests at the lowest design temperature are accepted according to specified requirements?
Reply (2): No, per para. 802.13(b), the Code does not apply to piping with metal temperatures
below -20°F.
Question (3): Is the design factor F = 0.6 acceptable for these lines (para. 841.122) [reference
Question (I)]?
Reply (3): The ASME B31.8-1989 Edition does not apply to these lines.
Interpretation: 10-7
Subject:
ASME B31.8-1989 Edition, Paragraph 827
Date Issued:
August 2, 1993
File:
B31-92-055
Question: (1): Does ASME B31.8, para. 827 allow only repair of defective welds in accordance
with API 1104?
Reply (1): No. Para. 827 also allows the removal of the defective weld.
Question (2): Under para. 827, are welding procedures and welders qualified in accordance
with the ASME BPV Code, Section IX per para. 823.2 also acceptable.
Reply (2): Yes. Welding procedures and welders qualified per para. 823.2 are acceptable to
repair defective welds in accordance with API 1104.
831.8 Interpretations No. 10
10-8, 10-9, 10-10
Interpretation: 10-8
Subject:
ASME B31.8-1989 Edition, para. 831.6, Calculation of Extruded Outlets
Date Issued:
August 30, 1993
File:
B31-92-047
Question (1): For an extruded outlet to meet the rules of ASME B31.8-1989 Edition, para.
831.6, must the actual thickness of the run wall T,be essentially a constant thickness over the entire
run pipe reinforcement zone?
Reply (1): Yes. If the run pipe wall thickness varies, then the T, used for para. 831.6 area
replacement calculations shall be the minimum thickness found in the run pipe reinforcement zone.
Question (2): For an extruded outlet to meet the rules of para. 831.6, must the width of the
reinforcement zone outside the branch wall, r, - dl2, be constant?
Reply (2): Yes.
Note: If the rules of para. 831.6 are not met, the extruded outlet may be qualified in accordance
with para. 831.36.
Interpretation: 10-9
Subject:
ASME B31.8-1989 Edition, Paras. 831.11 and 831.21(a), Use of API 6A Flanges
With API 6A Valves
Date Issued:
August 30, 1993
File:
B31-93-019
Question: In using a flanged valve per API 6A (permitted by para. 831.11) may weld neck line
pipe flanges per API 6A be used to mate to the valve, even though API 6A flanges are not listed
in para. 831.21(a)?
Reply: Yes.
Interpretation: 10-10
Subject:
ASME B31.8-1989 Edition, Para. 841.11, Allowance for Thread Depth
Date Issued:
August 30, 1993
File:
B31-93-020
Question: In para. 841.11, should the nominal wall thickness be reduced by the nominal thread
depth (dimension h of ANSVASME B1.20.1, or equivalent)?
Reply: Yes. See also para. 841.113(b).
38
831.8 Interpretations No. 10
Interpretation: 10-11
Subject:
ASME B31.8-1989 Edition, Para. 841.221, Use of API 5CT Casing and Tubing for
Pipeline Construction
Date Issued:
August 30, 1993
File:
B31-93-021
Question: Per para. 811.221, may tubing or casing per API SCT be used for pipeline construction
provided weldability is not an issue (threaded connections are used rather than welded connections)
and provided operating temperatures are such that ductility is equivalent to other materials which
are referenced in ASME B31.8?
Reply: Yes.
INTERPRETATIONS NO. 11
Replies to Technical Inquiries
September 1,1993, Through January 31,1999
Interpretations 11-1 Thmgh 11-26
It has been agreed to publish intepretations issued by the B31 Committee concerning B31.8 as part
of the update service to the Code. The interpretations have been asssigned numbers in chronological
order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of
the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may
have superseded the reply.
These replies are taken verbatim from the original letters, except for a few typographical and editorial
corrections made for improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional information
that the inquirer believes might affect the interpretation is available. Further, persons aggrieved by an
interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement
of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse" any item,
construction, proprietary device, or activity.
Subject
.
Interpretation
Appendix F. Extruded Headers...............................................
Clarification of Specified Strength of Fittings ...................................
Codc Applicability.........................................................
Design of Slug Catchers ....................................................
EPrthquake Design.........................................................
Exvuded Pipe ............................................................
Mill Certificates...........................................................
Para. 81l.l(d). Use of Aluminum Pipe ........................................
Paras 826.1 and 826.2. Inspection and Testing Welds ............................
Para. 831.32. Special Fittings ................................................
Para. 831.373. Minimum Design Metal Temperature .............................
Para 833. Stresses from External Loads .......................................
Para. 833. Combined Stress Calculations.......................................
Para. 840.42. Additional Protective Devices ....................................
Paras. 841.1 14(b) and 841.854. Change in Location ClassRoad Crossing ............
Para 841.121. Fabricated Assemblies .........................................
Para. 841.231, Bends .......................................................
Para. 84124. Notches ......................................................
Para. 841244. Arc Bums ...................................................
Para 842.5 I. Tie-Ins .......................................................
Para. 85 1.43(d), Permanent Field Repair of Leaks and Non-Leaking Corroded
11-25
11-15
11-5
11-7
11-26
11-22
1 1-23
11-14
11-4
11-16
11-1 1
11-1
11-9
11-20
11-6
11-17
11-18
11-3
11-2
11-13
.
.
Areas
.
.
.................................................................
Para 856.1. Reconversion of Steel Pipe .......................................
Para A842.22 1 Comsion Allowance .........................................
Para. A842.223. Combined Stress ............................................
Safety Corridor for Gas Pipeline .............................................
Table A842.22. Basic Design Factors .........................................
.
File
8 3 1.8 Intqmmions No. 1I
Subject: ASME B31.8-1995, Para.833, Stresses from External Loads
Date Issued: April 20, 1995
File: B3 1-94-046
Question (1): Is para. 833 applicable to above ground piping only, or can it be applied to buried piping
as well?
Reply (1): Paragraph 833 applies only to above ground piping.
Question (2): If para 833 is applicable only to above ground piping, what is the proper method of
combining stresses due to external loads on buried piping, and what are the acceptable limits of these
stresses?
Reply (2): The B31.8 Code does not address combined stresses for buried pipelines.
Intwpmtation: 11-2
Subject: ASME B3 1.8-1995, Para.841244, Arc Bums
Date Issued: April 20, 1995
File: B31-94-049
Question: For a series of pipe stringers operating below 40% of SMYS, the 20% solution of ammonium
persulfate test on ground out arc bumed areas shows blackened spots indicative of metallurgical notches.
If ultrasonic testing shows that the remaining wall exceeds the minimum wall strength or if the pipe is
rehydrostatically tested, would this pipe be suitable for gas transmission under the B31.8 Code?
Reply: The B31.8 Code does not address the treatment of arc bums on pipe operating at a hoop stress
less than 40% of the SMYS.
Interpretation: 11-3
Subject: ASME B31.8-1995,Para. 841.24, Notches
Date Issued: April 20, 1995
File: B3 1-94-050
Question: ASME B3 1.8, para. 841.24 required that "notches" must be prevented, eliminated, or repaired
in pipelines and mains to operate at a hoop stress of 20% or more of the specified minimum yield strength.
Does this requirement also apply to metallurgical notches?
Reply: Yes. The B3 1.8 Code does not make a distinction between "geometric notches" and "metallurgical
notches."
831.8 ~
:-I
o
n No. sI I
11-4
Subject: ASME B31.8-1995, Paras. 826.1 and 826.2, Inspection and Testing Welds
Date Issued: January 1, 1997
File: B31-95-033
Question: Hoop stresses are used to determine if qualifications of procedures and welders shall be in
accordance with para. 823.1 or 823.2. Should hoop stress be similarly used to determine if weld inspections
and/or tests of welds shall be in accordance with para. 826.1 or 826.2?
Reply: Yes.
Subject: ASME B31.8-1992, Code Applicability
Date Issued: April 16, 1997
File: B3 1-94-060
Question: Does ASME B31.8-1992 apply to the design and fabrication of a barge to be used for the
transportation of compressed natural gas?
Reply: No.
1
m
-:
11-6
Subject: ASME B3 1.8-1995, Paras. 841.11qb) and 841.854, Change in Location ClassJRoad Crossing
Date Issued: April 16, 1997
File: B31-95-049
Question (1): Does the Code address changes in design factor after a pipeline is constructed?
Reply (1): No.
Question (2): Does Table 841.114B apply when a road is built over or parallel to an existing pipeline?
Reply (2): No.
Question (3): Does the Code identify the limits beyond the pavement proper that the design factors for
road crossings in Table 841.1 14B must apply?
Reply (3): No.
Question (4): Does the Code f i n e the distance from the edge of the road where the design factors for
"parallel encroachment" in Table 841.114B must apply?
Reply (4): No.
B31.8 Intapretations No. 11
Subject: ASME B3 1.8-1995, Design of Slug Catchers
Date Issued: April 16, 1997
File: B31-%-038
Question: Would the B31.8 Code be applicable for the design of a slug catcher installed in a processing
plant inlet receiving gas from a pipeline that contains free liquids?
Reply: Please see para. 802.11 for applicability of your situation.
I M q m t d o n : 11-8
Subject: ASME B31.8-1992, Para. 856.1, Reconversion of Steel Pipe
Date Issued: April 21,1997
File: B3 1-94-051
Question: Does para. 856.1 of ASME B31.8-1992 apply in any way to the re-conversion of a steel
pipeline from gas transportation back to liquid transportation, the original function of the pipeline?
Reply: No.
Intorprofdon: 118
Subject: ASME B31.8-1995, Para. 833, Combined Stress Calculations
Date Issued: April 21, 1997
File: B3 1-94-052
Question: Do the requirements of para. 833 apply to buried pipe?
Reply: No. Please see para. 832.1.
Intqmtation: 11-10
Subject: ASME B3 1.8-1995, Para. A842.223, Combined Stress
Date Issued: April 21, 1997
File: B3 1-95-040
Question (1): Is the word "longitudinal" c o m t in the last two sentences of para. A842.223?
Reply (1): No.
Question (2): If the word "longitudinal" is incomt in these two sentences, should the word "combined"
replace "longitudinal" in either or both sentences?
Reply (2): Yes, in both sentences.
B31.8 Interpntations No. 11
Interpretation: 11-11
Subject: ASME B31.8-1995, Para. 831.373, Minimum Design Metal Temperature
Date Issued: April 22, 1997
File: B3 1-94-025
Question: When a closure head is designed to the requirements of ASME B3 1.8, is the minimum design
metal temperature determined by ASME Section VIII, Division 1, UG-20 including the requirements of
UCS-66 when appropriate, or is the MDMT established under the provisions of B3 1.8?
Reply: The B3 1.8 Code does not utilize the term "minimum design metal temperature" or define a similar
term with the same meaning.
Interpretdon: 11-12
Subject: ASME B3 1.8-1992, Para. 85 1.43(d), Permanent Field Repair of Leaks and Non-Leaking
corroded Areas
Date Issued: August 26, 1997
File: B3 1-96-004
Question: The purpose of this Inquiry is to clarify my understanding of the method of repair referred to
in para. 851.43(d). Surely if a nipple is welded over a small leak "to vent gas while welding" there is a
possibility that the gas will ignite when the welding arc is struck, thereby causing a hazardous situation.
If the leak were plugged with a tapered piece of wood, I could accept the philosophy behind this kind of
repair.
Reply: This is an established and widely accepted practice for repairing small leaks. The gas is intentionally
ignited and kept burning during the procedure, thus preventing an explosive mixture from developing.
Interpretation: 11-13
Subject: ASME B31.8-1995, Para. 842.5 1, Tie-Ins
Date Issued: December 3 1, 1997
File: B31-94-026
Question: When it is necessary to make a field repair to a damaged or defective portion of plastic pipe
by cutting out and replacing a cylinder as required by paras. 842.45 and 852.52, is this the same as a tiein section as described in para. 842.51 and therefore exempted from testing requirements except for testing
the tie-in joints?
Reply: No. The section of pipe installed as a replacement of a damaged or defective portion of plastic
pipe is not the same as a tie-in section as described in para. 842.51.
B31.8 1n-m
No. 11
Subject: ASME B3 1.8- 1995, Para. 811.l (d), Use of Aluminum Pipe
Date Issued: December 3 1, 1997
File: B31-94-061
Question (1): Does the reference to aluminum structure in Appendix K mean that aluminum pipe is
qualified for use by the rules of B3 1.8?
Repiy (1): No.
Question (2): If not, can aluminum pipe be qualified for use by the provisions of 8 11.l(d)?
Reply (2): Yes.
Question (3): If the reply to Question (1) or (2) is yes, must the pipe be manufactured in accordance
with ASTM (or equivalent) specification?
Reply (3): No.
Question (4): If the reply to Question (1) or (2) is yes, do the requirements in Chapter I1 apply?
Reply (4): No.
Question (5): If the reply to Question (1) or (2) is yes, do the welding requirements in Chapter IV apply?
Reply (5): No.
Interpretation: 11-15
Subject: ASME B31.8-1995, Clarification of Specified Strength of Fittings
Date Issued: December 31, 1997
File: B31-95-039
Question: Does ASME B31.8 allow a SMYS of 42,000 psi to be used for ASTM A 234 Grade WPB
fittings on the basis of materials tests?
Reply: No. The specified minimum yield strength properties are established by the applicable component
material, and product form specifications. Refer to para. 831.3 for applicable fitting specifications. Refer
also to Appendices B and C for applicable material and product form specifications.
B3 1.8 Inteqmtations No. 11
n
It-:
11-16
Subject: ASME B31.8-1995, Para. 831.32, Special Fittings
Date Issued: December 31, 1997
File: B31-96-003
Question: According to the stipulation of para. 831.32, "When special cast, forged, wrought, or welded
fittings are required to dimensions differing from those of regular shapes specified in applicable American
National and MSS Standards, the provisions of para. 801.4 shall apply." In fact, the para. 801.4 does not
exist in the Code. What shall one do while using nonstandarddimension fittings?
Reply: ASME B31.8- 1995 states, "...the provisions of para. 831.36 shall apply."
Interpretation: 11-17
Subject: ASME B31.8- 1995, Para. 841.12 1, Fabricated Assemblies
Date Issued: December 3 1, 1997
File: B3 1-97-010
Question: As defined in para. 841.121, are permanent above ground facilities designed to launch and
receive pipeline pigs considered fabricated assemblies?
Reply: Yes.
Intorprotation: 11-18
Subject: ASME B3 1.8-1995, Para. 841.231, Bends
Date Issued: December 31, 1997
File: B3 1-97-016
Question (1): When para. 841.231(b) expresses maximum deflection in an arc length equal to the outside
diameter, does it mean that bends shall be made minimum every single length equal to the outside diameter?
Reply (1): No. See para. 841.23 1(c).
Question (2): Is it possible that the requirements of ASME B31.8 specify clearly the minimum distance
between cold bends as a function of the pipe outside diameter, wall thickness, yield strength, or any other
parameters?
Reply (2): No.
--..
B31.8 I n t a p d o n s No. 1I
Subject: ASME B31.8-1995, Para. A842.22 1, Corrosion Allowance
Date Issued: March 12, 1998
File: B31-97-011
Question (1): Does the nominal wall thickness in the formula in para. A842.221 include corrosion
allowance?
Reply (I): No.
Question (2): Does the formula in para. A842.221 restrict the use of corrosion allowance in designing
offshore pipelines?
Reply (2): No.
Interpretation: 11-20
Subject: ASME B31.8-1995,Para. 840.42, Additional Protective Devices
Date Issued: March 12, 1998
File: B31-97-012
Question: In an area where the concentration of people has increased so the area has changed from a
Location Class 1 to a Location Class 3, is it possible to install additional protective devices such as automatic
shutdown valves in the line to seal off that portion of the line that was designated Class 3 and reclassify
the line to a Location Class 2 on the basis that these additional safety measures would be an alternative to
derating the pipe or installing heavier wall pipe?
Reply: No.
Intorprotation: 11-21
Subject: ASME B3 1.8-1995, Table A842.22, Basic Design Factors
Date Issued: March 12, 1998
File: B3 1-97-034
Question (1): We inquire of your Committee the rationale of limiting the basic design factor for submarine
pipelines to a universal value of 0.72.
Reply (1): The ASME B31.8 Committee is limited strictly to interpretation of the rules. ASME does
not act as a consultant on the general application or on the understanding of the Code rules.
Question (2): Would the Committee consider a basic design factor of 0.80 to be appropriate for offshore
pipelines?
Reply (2): No.
B3 1.8 Interpretations No. I I
Int.rpretatbn: 11-22
Subject: ASME B3 1.8-1992,Extruded Pipe
Date Issued: July 6, 1998
File: B3 1-94-002
Question: In Table El of the B31.8-1992Edition, which stress intensification factors apply for extruded
outlets covered in Appendix F?
Reply: The appropriate factors are those shown for extruded welding tee unless extrusions meet
requirements of a welding tee per ANSI B 16.9.
Interpretdon: 11-23
Subject: ASME B3 1.8-1995,Mill Certificates
Date Issued: July 6, 1998
File: B3 1-97-023
Question: Does ASME B31.8 require mill (material) certificates (chemical composition) for line pipe
and its components to be provided as part of the specification?
Reply: No.
Interpretation: 1 1-24
Subject: ASME B3 1.8-1995,Safety Corridor for Gas Pipeline
Date Issued: July 6, 1998
File: B3 1-97-057
Question: Does the ASME B3 1.8 Code define the minimum clearance between a pipeline and a building
intended for human occupancy? That is, does it specify a "safety comdor?"
Reply: No.
-.
1
B3 1.8 Interpdons No. 11
Subject: ASME B3 1.8- 1995, Appendix F, Extruded Headers
Date Issued: July 13, 1998
File: B3 1-96-042
Question (1): May a portion of an extruded header located outside of the zone of reinforcement have a
thickness less than T, but greater than or equal to t, as defined in Figures 3 and 4 of Appendix F?
Reply (1): ASME B31.8-1995 is titled Gas Transmission and Distribution Piping Systems. Appendix
F of ASME B31.8-1995 is intended as a nonmandatory guide to engineers using the Code in their day-today workings on gas piping systems. A manufacturer of fittings should be designing fittings to the codes
written specifically for that purpose: ASME B16.5 and MSS-SP75.
Question (2): Do the dimensions of the reinforced zone as defined in Figures 3 and 4 of Appendix F
apply in a plane transverse to the axis of the run or carrier pipe?
Reply (2): ASME B31.8-1995 is titled Gas Transmission and Distribution Piping Systems. Appendix
F of ASME B31.8-1995 is intended as a nonmandatory guide to engineers using the Code in their day-today workings on gas piping systems. A manufacturer of fittings should be designing fittings to the codes
written specifically for that purpose: ASME B16.5 and MSS-SWS.
Interpretation: 11-26
Subject: ASME B3 1.8-1995, Earthquake Design
Date Issued: January 5, 1999
File: B3 1-96-005
Question (1): Does ASME B31.8-1995 have any requirements or guidelines for earthquake design or
safety verification of buried pipelines?
Reply (1): No.
Question (2): Does ASME B3 1.8-1995 have any requirements relating to the use of seismic safety valves
to be used in urban areas?
Reply (2): No.
ASME B31.8 INTERPRETATIONS
VOLUME 12
Replies to Te!chnical IaquirieB
February 1,1999 l h m g b June 38,2801
Intecpmbthm 12-1TBrosgh 12-9
It has been agreed to publish intqmtations issued by the B31 Committee concerning B31.8 as part
of the update service to the Code. The inteqdations have ban asssigned numbers in chronological
order. Each interpetation applies either to the latest Edition or Addenda at the time of issuance of
the intcrpntaton or the Edition or Addenda stated in the reply. Sukqwnt revisions to the Code may
have superseded the reply.
These replies arc taken verbatim from the original letters, except for a few typographical and editorial
corrections made for improved clarity.
ASME procuiwes provide for reconsideration of these interp.etations when or if additional information
that the inquirer believes might affkct the interpFetation is available. F~lrther,persons aggrieved by an
interprtaton may appeal to the cognizant ASME amunittee or subcommittee. As stated in the Statement
of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endor&' any item,
construction, proprietary device, or activity.
File
-
subject
B31.8-1989 Edition, Cettification of a Listed Material to Another Listed
Speciktion
...........................................................
B31.8-1995 Edition, Para.842.43l(g), Direct Burial .............................
B31.8-1995 Edition, Para.A843.1, Wave md Current Conditions ..................
B310 and B31.8-1995 W o n , Para. 841.1 13(b), Additional Requimnents for Nominal
Wdlnticlwsci t i n Pam. 841.11 ...........................................
Para 841.1l(a), Duign Factor. ..............................................
Para. 841.11(~)(2).........................................................
Paras. 8%.1(c) urd 854.l(cX5). Requimmnts for Class Location Change Study ......
Tabk 841.1 14B, kip FIdor for Steel Pipe Construction .......................
Utilization of Duplex Stainless Steel ..........................................
B31.8 Interp-tions
Vol. 12
Interpretation: 12-1
Subject: Paras. 854.1(c) and 854.1(~)(5),Requirements for Class Location Change Study
Date Issued: August 27, 1998
File: B3 1-98-010
Question (1): If the location class changes from Class 1 to Class 4, is a study required under para.
854.1(c)?
Reply (1): Yes.
Question (2): Are fences and concrete bamers installed along the pipeline within the meaning of "physical
barriers" in para. 854.1(~)(5)?
Reply (2): No.
Question (3): Does para. 854.l(c)(5) require a "risk assessment study"?
Reply (3): No. It is up to the ownerloperator to determine what types of studies are needed to meet the
requirements.
Subject: B31G and B31.8-1995 Edition, Para. 841.1 13(b), Additional Requirements for Nominal Wall
Thickness t in Para. 841.11
Date Issued: May 11, 1999
File: B3 1-95-029
Question (1): Can B31G be used to evaluate pipe based on remaining wall thickness for corrosion that
has o c c d during the installation stage?
Reply (1): B31G is not applicable to new construction covered under the B31.8 Code.
Question (2): Can para. 841.113(b) be used as criteria for evaluating this corrosion?
Reply (2): No. The B31.8 Section Committee is currently reviewing the Code to determine whether
corrosion under the situation you describe should be addressed.
Interpretation: 12-3
Subject: B3 1.8-1995 Edition, Para. A843.1, Wave and Current Conditions
Date Issued: May 11, 1999
File: B3 1-98-021
Question (1): Is it practical to determine the most unfavorable expected combination of wave and current
conditions?
Reply (1): Yes.
Question (2): If so, how?
Reply (2): The ASME B31.8 Committee is limited strictly to the interpretation of the rules. ASME does
not act as a consultant on the general application or on the understanding of the Code rules.
831.8 InteQieations Vol. 12
I n t q m M o n : 12-4
Subject: B31.8-1989 Edition, Certification of a Listed Material to Another Listed Specification
Date Issued: August 3, 1999
File: B31-94-048
Question: Does the B31.8 Code address the certification of a listed material to another listed material
specification by a service center/processor?
Reply: No.
n
:1
-
126
Subject: B31.8- 1995 Edition, Para. 842.431(g), Direct Burial
Date Issuad: August 3, 1999
File: B31-98-015
Question (1): Is para. 842.431(g) an obligatory requirement for the design execution of 4 bar, direct
burial, gas plastic piping systems, in order to comply with the B31.8 Code?
Reply (1): No.
Question (2): In case para. 842.431(g) is obligatory, can DEPA utilize in plastic pipe systems the
digital mapping Ooographic Information System (GIs) and pipe routing, indicating post marks instead of
electronically conductive wire to satisfy the B31.8 Code requirements?
Reply (2): See reply to Question (1) above.
IWwpmtdon: 12-6
Subject: Table 841.114B, Degign Factor for Steel Pipe Construction
Date Issued: February 24, 2000
File: B31-99-031
Question (1): Per Table 841.1 14B, does a gas pipeline (which is c o v e d by B31.8) that skirts a compressor
station facility just inside the fence of the facility, but is not associated with the compmsion process within
the facility and exterior to the station emergency shutdown system, need to be designed using a 0.5 or 0.4
design factor?
Reply (1): No.
Question (2): If the answer to Question (1) is no, if the location class allows, and if it is not a fabricated
assembly, is a 0.72 design factor acceptable?
Reply (2): Yes.
Question (3): Is a nitrogen gas pipeline covered by the B31.8 Code?
Reply (3): No.
Question (4): If the answer to Question (3) is no, is it because nitrogen is an inert gas and use of B31.8
for the design of nitrogen gas pipeline will be more stringent than necessary?
Reply (4): No.
Intwpntcltion: 12-7
Subject: Para. 841.1 1(a), Design Factor
Date Issued: January 3, 2001
File: B3 1-97-058
Question: For pipe produced in accordance with a specification approved in B3 1.8, can t in the design
formula be adjusted above nominal if the wall thickness is guaranteed to be greater than the minimum
allowed by the specification?
Reply: No.
Intorprotation: 12-8
Subject: Para. 841.11(c)(2)
Date Issued: January 3,2001
File: B31-99-019
Question: My analysis indicated the AISI constant should be 0.0339 for a full-size specimen. The B31.8
Code constant is 0.0345. Would the B31.8 Section Committee consider reviewing the derivation of this
constant in the Code?
Reply: Yes.
Intqmtdon: 12-9
Subject: Utilization of Duplex Stainless Steel
Date Issued: January 3, 2001
File: B31-95-030
Question: Does B31.8 allow the utilization of duplex stainless steel pipe?
Reply: Yes.Please see paras. 802 and 811.
ASME B31.8 INTERPRETATIONS
VOLUME 13
Replies to Technical Inquiries
July 2001 Through December 2003
Interpretations 13-1 Through 13-8
It has been agreed to publish intepretations issued by the B31 Committee concerning B31.8 as
part of the update service to the Code. The interpretations have been asssigned numbers in
chronological order. Each interpretation applies either to the latest Edition or Addenda at the
time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent
revisions to the Code may have superseded the reply.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information that the inquirer believes might affect the interpretation is available. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee.
As stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
Subject
Interpretation
Paras. 823.21.824.1.825.1. and 825.2 .......................................
Para 831.22(d). Bolting ...................................................
Para 831.4l(d). ..........................................................
Para. 833................................................................
Paras. 841.321.841.33. and 852.51 ..........................................
Para 854.4@)(2). .........................................................
Appendix F. Fig F5 ......................................................
Code Conformance.......................................................
13-7
13-5
13-2
13-1
13-6
13-4
13-8
13-3
.
.
.
.
Subject: ASME B31.8, Para. 833
Date Issued: August 11,2000
Pile: B31-00-002
Question (1): Does para. 833.4(b) require that the longitudinal stress due to internal pressbe calculated using the pressure design equation in para. 841.11?
Reply (1): No.
Question (2): Does para. 833.2 require that stresses due to weight of the pipe be combined with
stresses due to thermal expansion?
Reply (2): No.
Question (3): Does para. 833.4 apply to a fully restrained section of pipeline?
Reply (3): No.
Question (4): Does para. 833.4 limit the thermal expansion stress range to 0.72 SMYS, the sum
of longitudinal stresses due to pressure and weight to 0.75 SMYS,and the sum of the thermal
expansion stress rqnge and the longitudinal stresses due to pressure and weight to 1.0 SMYS?
Reply (4): Yes.
Question (5): Do we need to consider the longitudinal joint factor E in the calculation of
allowable hoop stress for offshore pipelines as specified in para. 841.11 for onshore pipelines?
Reply (5): No.
Question (6): Can a hoop stress design factor of 0.80 be used for an offshore pipeline design?
Reply (6): No.
Subject: ASME B31.8, Para. 831.41(d)
February 14,2002
File: B31-99-032
C>
Question: Where the diameter of the finished opening for a branch connection is smaller than
the inside diameter of the branch pipe, is it permissible to include as available reinforcement
excess thickness in the header wall located between the finished opening and the branch wall.
Reply: Yes.
Interpretation: 13-3
Subject: ASME B31.8 Code Conformance of Pikotek Flanges
Date Issued: March 21,2003
File: B31-01-005
Question: In order to comply with the Code requirements of ASME B31.8, is it permissible to
use Pikotek gaskets as unlisted components in standard B16.5 flanges and operate at higher
working pressures and temperatures than those listed in ASME B16.5-1996 (Tables 2 listed under
Pressure-Temperature Ratings) provided the calculated flange (and bolt) stresses remain below
the allowable stresses outlined in the applicable ASME Boiler and Pressure Vessel Code (as
specifically detailed in memorandum titled "Code Conformance of Pikotek Flanges" dated April
7, 1997)?
Reply: No.
Interpretation: 13-4
Subject: ASME B31.8-1999, Para. 854.4@)(2)
Date Issued: May 8, 2003
File: 02-3705
Question: Is it mandatory, per para. 854.4@)(2)that additional sectionalizing block valves be
installed to conform to the spacing requirements in para. 846.11, when one mile or more of
transmission line is replaced to maintain the established MAOP in conjunction with a change in
location class?
Answer: No.
Interpretation: 13-5
Subject: ASME B31.8, Para. 831.22(d), Bolting
Date Issued: May 15, 2003
Item: B31-01-004 (formerly B31-00-003)
Question (1):Do ASTM A 563 nuts meet the requirements set forth in para. 831.22(d) for use
with ASTM A 307 bolts?
Reply (1): No. As written, only ASTM A 194 or A 307 may be used. However, per para. 811.22,
other materials may be qualified for use as described in para. 811.221 or para. 811.222.
Question (2): If ASTM A 563 nuts meet the requirements set forth in para. 831.22(d), are Grade
A, Heavy Hex nuts required to match ASTM A 307 Grade B bolts?
Reply (2): See Reply 1.
Interpretation: 13-6
Subject: Appendix F, Fig. F5, Definition of dimension L
Date Issued: September 21,2003
File: 03-155
Question: If the L dimension for a welded-on fitting (integrally reinforced) lies entirely within
the fitting, then for the purposes of extra area replacement per para. 831.41(e), is L then equal to
2?4H, where H is the nominal wall thickness of the header?
Reply: Yes, provided 2 % is~smaller than 2 % +~M.
Interpretation: 13-7
Subject: Paras. 823.21, 824.1, 825.1, and 825.2
Date Issued: September 28,2003
File: 03-154
Question (1): Is it mandatory that welds in all carbon steels be stress relieved when the
wall thickness exceeds 1%in. even if hardness requirements have been achieved without stress
relieving?
Reply (1):Yes, ASME 831.8 para. 825.2 requires carbon steel welds shall be stress relieved when
the nominal wall thickness exceeds 1%in.
Question (2): Is preheating mandatory for carbon steels having a carbon content less than 0.32%
or a carbon equivalent (C + 1/4 Mn) less than 0.65%?
Reply (2):No, unless the weld procedure requires such treatment to produce satisfactory welds.
Question (3):Is stress relieving mandatory for carbon steels having a carbon content less than
0.32% or a carbon equivalent (C + '/4 Mn) less than 0.65%?
Reply (3): No, provided all of the other requirements are met.
Question (4): If a'weld procedure for sour gas service is qualified under ASME para. D( and
the procedure meets the hardness requirements as specified in NACE MR0175 without preheating
and stress relieving are preheating and stress relieving still r e q u i d under ASME B31.8 paras.
824.1 & 825.2?
Reply (4): Yes, para. B801 indicates that "if a paragraph appearing in Chapters I through VII
does not have a corresponding paragraph in this chapter, the provisions apply to sour gas service
without modification."
Interpretation: 13-8
Subject: Pipe bend at 30% SMYS or greater, Paras. 841.321, 841.33, and 851.51
Date Issued: October 21,2003
File: 02-3938
Question: Does ASME B31.8 address field bending of pipe after hydrostatic testing?
Reply: No.
ASME 631.8 INTERPRETATIONS
VOLUME 14
RepUes to Tachnical Inquiries
January 2004 Through December 2006
Interpretations 14-1 Through 14-10
It has been agreed to publish interpretations issued by the 831 Committee concerning B31.8
as part of the update service to the Code. The interpretations have been asssigned numbers in
chronological order. Each interpretation applies either to the latest Edition or Addenda at the
time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent
revisions to the Code may have superseded the reply.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for impmved clarity.
ASME p r o c e d y pmvide for reconsideration of these interpretations when or if additional
information that the inquirer believes might affect the interpretationis available. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee.
As stated in the Statement of Policy in the Code documents, ASME does not "approve," "cerhfy,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
ASME 831.8 INTERPRETATIONS VOWME 14
B31.8
Subject
Code Conformance of Flanges Listed to ASME B16.47 .......................
Establishment of t- for 831.8. ............................................
New Road in Parallel Enaoachment With an Existing Pipeline................
Para. 80211 .............................................................
Para. 833.4 ..............................................................
Para. 846.11(c). Sectionalizing Valve Spacing ................................
Para. 851.51 .............................................................
Para. A842.223. Combined Stmm Criteria ...................................
Paras. A834 and A842.27..................................................
Table 854.1(c), Change in Number of Buildings With Respect to Location
Class .................................................................
Interpretation
ASME 831.8 INTERPRETATIONS VOLUME 14
Interpretation: 14-1
Subject: ASME B31.8-1995 Edition, Para. A842.223, Combined Stress Criteria
Date Issued.. August 3, 1999
File: B31-99-002
Question (1): Are either the Von Mises or Tresca equations acceptable under para. A842.223
for considering combined stress?
Reply (1): Yes.
Question (2): In para. A842.223, does "limiting longitudinal stress" mean limiting combined
stress?
Reply (2): Yes.
Subject: ASME B31.8, Para. 846.11(c), Sectionalizing Valve Spacing
Date Issued: March 13,2002
File: 02-2542
Question: Except for the slight adjustments permitted in para. 846.11(c), are there any provisions
in the B31.8 Code that will allow a spacing of valves in a Class 1Location to exceed 20 miles?
Reply: No.
Subject: ASME B31.8-1999 Edition, Code Conformance of Flanges Listed to ASME B16.47
Date Issued: July 14,2003
File: 02-2884
Question: Does the ASME 831.8 Code permit the use of flanges manufactured in accordance
with ASME B16.47 (Series A or B)?
Reply: Yes; refer to section 811of ASME B31.8 for additionalinformation regarding qualification
of materials and equipment for use in this Code.
ASME 831.8 INTERPRETATIONSVOLUME 14
Interpretation: 14-4
Subject: ASME 831.8-1999 Edition, New Road in Parallel Encroachment With an Existing Pipeline
Date Issued: February 12, 2004
File: 02-2547
Question (1): An existing pipeline was originally located in a Class 1,Division 2 location using
a Design Factor of 0.72. There were no roads when the pipeline was built. A new road has been
built within the same right-of-way. Does section 854, Criteria for Class Location, apply?
Reply (1): No.
Question (2): An existing pipeline is located in a Class 1, Division 2 Location and a Design
Factor of 0.72 was used. If there is an existing parallel encroachment with a private road or
unimproved public road, and a new railroad is built within the pipeline right-of-way, does section
854 apply to determine the MAOP?
Reply (2): No.
Question (3): Does the Code address the addition of fences or surfacing of roads after the
pipeline is constructed?
Reply (3):No.
Question (4): In case of a pipeline located in a Class 1, Division 2 area tlyt crosses without
casing a public road, improved or unimproved, and also crosses its right-of-way, is the portion
of the pipeline that runs in the land between the right-of-way limit and the road considered (for
the purpose of Design Factor and depth of cover):
(a) a part of the crossing?
(b) as if it were a parallel encroachment?
(c) as a common portion of pipe in Class 1, Division 1, with a Design Factor of 0.721
Reply (4): The portion of the pipeline between the right-of-way and the &ad is considered a
part of the crossing.
Question (5): With regard to Table 841.114B, under "Crossing of roads . . .", item (c), does this
apply to roads or highways or public streets with both hard surface and railroads (rails installed
on hard surface street, with lanes for cars and lanes for trains), or does this apply to roads or
highways or public streets with a hard surface and railroads?
Reply (5): It is applicable to roads or highways or public streets with hard surface and also
applicable to'railraads, wherever the railroads are located.
Question (6): Does para. 840.22(d) include areas where all of the following conditions are
present:
(a) multistory buildings are prevalent
(b) traffic is heavy or dense
(c) there may be numerous utilities underground
Reply (6): Yes. Note para. W.22(d) also defines "multistory" as four or more floors. In Class 4
Locations, all of the above must exist.
ASME 831.8 INTERPRETATIONS VOLUME 14
Subject: ASME B31.8-1999 Edition, Para. 802.11
Date Issued: February 20,2004
File: 03-158
Question: Do the corresponding chapters (Materials, Welding, Design, and Testing) of
AsME B31.8 apply to underground ethylene pipelines operating in gas phase below the critical
point (50.3 bar), considering
(a) it is not a fuel line
(b) it was located onshore
(c) it is 140 km long and links two plants together
(d) it will be operating at below 5035 bars
(el it will be transporting ethylene in the gaseous phase
(f) the line was originally designed for oxygen service to ASME B31.8-1975 Edition.
Reply: The answer based on the above is yes.
Su*:
ASME B31.6-1999 Edition, Paras.A834 and A842.27
Date Issued: June 29,2004
File: 03-1792
Question (1): A portion of the topsides between the riser hangar flange and the launcher/
receiver is specdied as per B31.8 in lieu of B31.3 in order to maintain the constant inside diameter
of the pipe for p i e . Does the pipe support attachment require a full encircling member in
accordance with para. A834 since the portion of piping referenced above is not construed as a
riser or a pipeline?
Reply: (1) Yes. We agree that the portion of piping you are considering is not a riser or a
pipelme, but it is platform piping. Since para. A834 also covers platform piping, it does indeed
q u i r e a full encircling member in order to be in accordance with ASME 831.8.
Question (2): If the support is welded to a 120 deg pad by avoiding the direct welding of the
support to the piping and the computed local stress due to the support reaction is within the
Code allowable, does it suffice as per para. A842.27?
Reply (2): No. In order to be in accordance with ASME B31.8, you need to use a full encircling
member.
ASME B31.8 INTERPRETATIONS VOLUME 14
Interpretation: 14-7
Subject: ASME B31.8-1995 Edition, Para. 833.4
Date Issued: December 6,2004
File: 02-3377
Question (1): The last statement of para. 833.4 in the 1995 revision of the Code appears as,
"The sum of 833.403) and (c) shall not exceed 0.755"; however, para. 833.403) has the following
statement added in parentheses: "(see para. 841.11, SFT)". Does the following equation interpret
correctly these two revised statements?
0.75 X F
X
T
X
SLp + SLB < S
Reply (1): No.
Question (2): Or should it look now as: SLP + SLBc S?
Reply (2): No.
Interpretation: 14-8
Subject: ASME B31.8, Establishment of t-
for 831.8
Date Issued: December 6,2004
File: 03-1739
Question: Can ASME B31G be used to determine a minimum wall thickness for new pipe?
Reply: No.
L
Interpretation: 14-9
Subject: ASME B31.8-2003 Edition, Para. 851.51
Date Issued: December 6,2004
File: 04-246
Question: Does field bending a joint of pretested pipe negate the test, thus requiring a postbend test?
Reply: ASME B31.8 is silent on this issue.
f
Subjed: ASME B31.8-2003 Edition, Table 854.1(c), Change in Number of Buildings With Respect
to Location Class
Date Issued: December 7,2004
File: 04-93
Question: Can the "current" column in Table 854.1(c) be used for the purpose of patrols and
leakage surveys [paras. 854.1(d) and 851.2]?
Reply: Yes.
ASME B31.8 INTERPRETATIONS
VOLUME 1 5
Replies to Technical Inquiries
January 2007 Through September 2009
Interpretations 15-1 Through 15-11
It has been agreed to publish interpretations issued by the B31 Committee concerning
ASME 831.8 as part of the update service to the Code. The interpretations have been asssigned
numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda
at the time of issuance of the interpretation or the Edition or Addenda stated in the reply.
Subsequent revisions to the Code may have superseded the reply.
These replies are taken verbatim from the original letters, except for a few typographical and
editorial corrections made for improved clarity.
ASME procedures provide for reconsideration of these interpretations when or if additional
information that the inquirer believes might affect the interpretation is available. Further, persons
aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee.
As stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify,"
"rate," or "endorse" any item, construction, proprietary device, or activity.
a
Copyright 2010 by the American Society of Mechanical Engineers.
No reproduction may be made of this material without written consent of ASME.
B31.8
Subject
Interpretation
Allowable Hoop Stress for Offshore Hydrotest. Para . A847.2. .................
Alternate Acceptance Standard for Girth Welds in Appendix A of
API1104 ..............................................................
Para . 831.41Q-1). Seal Welding Vent Holes ....................................
Para.834.5 ..............................................................
Para . 841.11(c). Fracture Control and Arrest for Steel Pipe ....................
Para . 841.32 and Table 841.322(f). Testing Coefficients ........................
Para . 844.32 .............................................................
Paras . A801. A802. and A803. Minimum Temperature Application . . . . . . . . . . . . .
Table841.115A ...........................................................
Table 841.322(f). Maximum Test Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table A842.11. Note (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Copyright
2010 by the American Society of Mechanical Engineers .
No reproduction may be made of this material without witten consent of ASME .
.
File No
ASME B31.8 INTERPRETATIONS VOLUME 1 5
Interpretation: 15-1
Subject: ASME 831.8-2003, Sections A801, A802, and A803, Minimum Temperature Application
Date Issued: June 27,2005
File: 04-1649
Question (1): We would like to know if "General Provisions and Definitions" (in particular,
para. 802.12(b)) is completely replaced by Chapter VIII, sections A801, A802, and A803.
Reply (1): No. As stated in para. A802.2, the provisions of paras. A801, A802, and A803 only
supplement the provisions of paras. 801, 802, and 803. They do not replace them.
Question (2):If so, which is the minimum applicable temperature for Offshore Gas Transmission
Installation?
Reply (2): As stated in para. 802.12(b), the B31.8 Code is only applicable to pipelines having
a metal temperature down to and including -20°F.
Interpretation: 15-2
Subject: ASME B31.8, Para. 841.32 and Table 841.322(f), Testing Coefficients
Date Issued: December 12, 2005
File: 04-94
Question: Why is the coefficient for the Location Class 1, Division 1 higher than 1.1?
Reply: The coefficient reflects the Committee's opinion about the minimum test level necessary
to establish the pipeline's integrity for pipelines operating at a hoop stress above 72% of the
SMYS.
Interpretation: 15-3
Subject: ASME B31.8, Table 841.115A
Date Issued: May 21, 2007
File: 05-215
Question: Would helical (spiral) welded pipe have the same joint efficiency factor (E = 1.0) as
SAW pipe manufactured under API 5L?
Reply: Yes.
1-3
Copyright @ 2010 by the American Society of Mechanical Engineers.
No reproduction may be made of this material without witten consent of ASME.
ASME B31.8 INTERPRETATIONS VOLUME 15
Interpretation: 15-4
Subject: ASME B31.8, Para. 831.41(h), Seal Welding Vent Holes
Date Issued: November 8,2007
File: 06-259
Question (1): Is seal welding acceptable for plugging vent holes?
Reply (1): No. The Code recommends against the use of any material or techniques that would
contain pressure for plugging vent holes in rings or saddles used for reinforcement of branch
connections [see para. 831.41(h)].
Question (2):Can seal welding of vent holes on wear pads for pipe supports be used to prevent
crevice corrosion?
Reply (2): The Code does not address wear pads.
Interpretation: 15-5
Subject: ASME B31.8, Para. 841.11(c), Fracture Control and Arrest for Steel Pipe
Date Issued: September 9, 2009
File: 03-105
Question (1): Is material testing required to confirm that fracture toughness criteria specified
in accordance with para. 841.11(c)has been achieved?
Reply (1): Yes. Testing in accordance with paras. 841.11(c)(l)and (c)(2) is required.
Question (2): Is material testing required to confirm that the all-heat average Charpy energy
value meets or exceeds the required energy value as determined in accordance with
para. 841.11(~)(2)?
Reply (2): Yes.
Interpretation: 15-6
Subject: ASME B31.8-2003, Para. 844.32
Date Issued: September 9, 2009
File: 04-1083
Question (1):Is gas process piping (such as pipelines, headers, manifolds, etc), whether installed
above or below ground, defined as a pipe-type or bottle-type holder?
Reply: (1) No.
Question (2): If the answer to Question (1) is negative, then does the Code provide criteria for
establishing the distance from gas process piping to property and/or fence lines?
Reply (2): No.
Question (3): Do the requirements of para. 844.32(b) prohibit the installation of pipe-type and
bottle-type holders less than 100 ft from a fenced site boundary when the maximum operating
pressure is greater than or equal to 1,000 psig?
Reply (3): Yes.
1-4
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@)
ASME B31.8 INTERPRETATIONS VOLUME 1 5
Interpretation: 15-7
Subject: ASME B31.8, Table 841.322(f), Maximum Test Pressure
Date Issued: September 9, 2009
File: 06-1146
Question (1): Is there a maximum test pressure prescribed for location class-2 when the test
medium is water?
Reply (1): No.
Question (2): Is there a maximum test pressure prescribed for location class3 and 4 when the
test medium is water?
Reply (2): No.
Interpretation: 15-8
Subject: ASME B31.8, Para. 834.5
Date Issued: September 9, 2009
File: 07-1468
Question (1): For piping that is operating at 50% or more of SMYS, and a welded pipe support
connection is desired, is it necessary to provide a full encirclement sleeve, continuously welded
to the pipe, for attachment of the welded pipe support?
Reply (1): Yes.
Question (2): For piping that is operating at 50% or more of SMYS, is it necessary to provide
a full encirclement sleeve (welded or not welded) to the pipe when a nonwelded support connection is desired (such as a clamp)?
Reply (2): No.
Interpretation: 15-9
Subject: ASME B31.8-2007 Edition, Table A842.11, Note (1)
Date Issued: September 9, 2009
File: 09-1072
Question: Note (1) in Table A842.22 says combined stress for platform piping and risers shall
be based upon specified minimum wall thickness, including manufacturing, corrosion, and erosion
allowances. Is combined stress for pipeline to be based on nominal wall thickness?
Reply: Yes.
1-5
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Copyright 2010 by the American Society of Mechanical Engineers.
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ASME B31.8 INTERPRETATIONS VOLUME 1 5
Interpretation: 15-10
Subject: ASME B31.8-2007, Alternate Acceptance Standard for Girth Welds in Appendix A of
API 1104
Date Issued: September 9, 2009
File: 09-1073
Question: Can the alternative acceptance standard for girth welds described in Appendix A
of API 1104 be applied for onshore pipeline construction according to ASME B31.8?
Reply: Yes. Meeting the standards of acceptability of API 1104 implies the use of the document
in its entirety, including the appendices.
Interpretation: 15-11
Subject: ASME B31.8-2007 Edition, Allowable Hoop Stress for Offshore Hydrotest, Para. A847.2
Date Issued: September 11, 2009
File: 09-1503
Question: In ASME B31.8-2007, para. A847.2, it is addressed in the CAUTION section that
"When an external pressure, Pe, greater than zero is used in the hoop stress formula in para.
A842.221, there is a possible combination of conditions where the yield strength of the pipe could
be exceeded during the hydrostatic test. The hoop stress shall be checked to see that it is within
allowable limits considering both the internal and external pressures when determining the
maximum hydrostatic test pressure." However, it is not specified in the code what should be the
allowable limit for the hoop stress during hydrotest. Is there an allowable limit for the hoop
stress during hydrotest of an offshore pipeline?
Reply: No. The Code does not limit the hoop stress during hydrotest of an offshore pipeline
to a certain percentage of SMYS. The purpose of the cautionary note is only to alert the user that
under certain conditions, the hoop stress during hydrotest could be higher than anticipated.
a
Copyright 2010 by the American Society of Mechanical Engineers.
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