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TABLE OF CONTENTS
1.0
SCOPE
2.0 REFERENCES
4
2.1 Industry Codes and Staindards
5
2.2 CPOC General Specifications
7
3.0 GENERAL
7
3.1
Definitions
7
3.2
Abbreviations
8
4.0 GENERAL WELDING AND INSPECTION REQUIREMENTS
4.1
General
5.0 WELDING CONSUMABLES
5.1
6.0
4
General
11
11
12
12
5.2 Selection of Consumables
12
5.3
13
Essential Variables
5.4 Supply, Storage and Use
15
5.5
15
Drying Procedures and Use of Electrodes
5.6 Substitution of Materials
16
5.7
16
Material Inspection and Storage
QUALIFICATION OF WELDING PROCEDURE, PERSONNEL AND EQUIPMENT
16
6.1
General
16
6.2
Material Groups for Welding Conditions
17
6.3
Welding Procedure Specifications (WPS)
19
6.4
Welding Procedure Qualification Tests
21
6.5
Qualification of Welding Personnel
27
6.6
Welding Equipment
29
7.0 PRODUCTION WELDING
30
7.1
General Requirements
30
7.2
Welding Processes
32
7.3
Base Metal Preparation
33
7.4
Cutting and Edge Preparation
33
7.5
Welding Sequences
33
7.6
Tack Welds
34
7.7
Correction of Unacceptable Fit-ups
34
7.8
Weld Identification and Marking
35
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Tubular Splices
35
7.10 Beam Splices
36
7.11 Welded Connections
36
7.12 Fillet and Seal Welds
36
7.13 Stiffeners and Padeyes
37
7.14 Preheating and Interpass Temperature
37
7.15 Weld Profile
38
7.16 Arc Strikes
38
7.17 Weld Interruption
38
7.18 Post Weld Heat Treatment (PWHT)
39
7.19 Temporary Welds
40
7.20 Cleaning
41
8.0 INSPECTION AND TESTING
41
8.1
General
41
8.2
Qualification of NDT Procedures and Personnel
43
8.3
Radiographic Examination
43
8.4
Ultrasonic Examination
44
8.5
Magnetic Particle Inspection (MPI)
45
8.6
Liquid Penetrant Inspection (LPI)
45
8.7
Production Tests
47
9.0 WELDING REPAIRS
48
9.1
General
48
9.2
Method of Repair
50
9.3
Approval
50
10.0 DOCUMENTATION
51
LIST OF FIGURES.
52
ATTACHMENT 1 PROCEDURE, STANDARDS AND ACCEPTANCE CRITERIA FOR
58
STRUCTURAL WELDING
ATTACHMENT 2 NDT EXTENT FOR WELDING OF OFFSHORE STRUCTURES
58
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SCOPE
This Specification applies to all COMPANY Projects and defines the minimum requirements of
structural welding and inspection for the CPOC Block B-17 Field Development Area.
The specification defines the minimum requirements for welding process, welding
consumables, welding equipment, welding procedures, and qualification of welding procedures,
qualification of welders / welding operators, production welding, and weld inspection of offshore
structures, topsides and buildings onshore and offshore. This specification applies to shop, yard
and offshore welding.
This specification applies to fabrication, onshore and offshore installation for the structures as
shown in the Contract Documents; and also to sea-fastenings, temporary structures, construction
aids.
This specification shall also be used in conjunction with a Project Particular Specification (PPS)
detailing the additional requirements, based on the specific design conditions of the project.
2.0
REFERENCES
The reference documents listed below, including Industry Codes and Standards and COMPANY
specifications, form an integral part of this General Specification. Unless otherwise stipulated, the
applicable version of these documents, including relevant appendices and supplements, is the
latest revision published on the effective date of the contract.
The overall order of precedence of the applicable documents shall be:
1) Government Laws, Rules and Regulations
2) Purchase Order/ Service Order/ Contract Documents
3) Project Particular Specification (PPS)
4) Present General Specification
5) Codes and Standards in reference
Any conflict between any of the Contract Documents, or between this specification and any other
Contract Document, shall be reported to the COMPANY for decision. In such a case, and unless
otherwise agreed or decided by the COMPANY, it is understood that the more stringent requirement
shall apply.
Exceptions to, or deviations from this specification are not permitted unless previously accepted in
writing by the COMPANY. For this purpose, requests for substitutions or changes of any kind
shall be complete with all pertinent information required for COMPANY assessment.
COMPANY’s approval, nevertheless, will not, in any way, relieve the responsibility of the Supplier
to meet the requirements of the industry Codes and Standards referred to and amended herein, in
the event of conflict.
Applicable Codes and Standards which are to be used in conjunction with this specification shall be
as stated hereafter.
1
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Industry Codes and Standards
Reference
A 370
Title
Standard Methods and Definitions for Mechanical Testing of Steel Products
AISC
Manual of Steel Construction
ANSI / AWS D1.1
Structural Welding Code - Steel
API RP 2A
Recommended Practice for Planning, Designing and Constructing Fixed
Offshore Platforms – Working Stress Design
API RP 2X
Ultrasonic Examination of Offshore Structural Welding
ASNT TC-1A
Nondestructive Testing Personnel Qualification and Certification
ASTM E23
Notched Bar Impact Testing of Metallic Materials
AWS 5.29
Specification for Alloy Steel Electrodes and Fluxes for Cored Arc Welding
AWS A5.01
Structural Welding Code – Steel Filler Metal Procurement Guideline
AWS A5.1
Specification for Covered Carbon Steel Arc Welding Electrodes
AWS A5.17
Specification for Bare Mild Steel Electrodes and Fluxes for Submerged ArcWelding (SAW)
AWS A5.18
Specification for Carbon Steel Filler Metals for Gas Shielded Arc Welding
(GMAW)
AWS A5.20
Specification for Carbon Steel Electrodes for Flux Cored Arc Welding
(FCAW)
AWS A5.23
Specification for Alloy Steel Electrodes and Fluxes for Submerged Arc
Welding
AWS A5.5
Specification for Low-alloy Steel Covered Arc-Welding Electrodes
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Title
BS 7448
Fracture Mechanics Toughness Tests, Part 1 : Methods for
Determination of KIc, Critical CTOD and Critical J Values of Metallic
Materials, Part 2 : Method for Determination of KIc, Critical CTOD and
Critical J Values of Welds in Metallic Materials, Part 3 : Method for
determination of fracture toughness of metallic materials at rates of
increase in stress intensity factor of 3.0 MPa., Part 4 : Method for
Determination of Fracture Resistance Curves and Initiation Values for
Stable crack extension in metallic materials
BS 7910
Guide on Methods for Assessing the Acceptability of Flaws in Metallic
Structures
EEMUA 158
Construction Specification for Fixed Offshore Structures in the North Sea
ISO 1000
International System of Units
ISO 148
Charpy Impact Test (V-notch)
ISO 19902
Petroleum and Natural Gas Industries - Fixed Steel Offshore Structures
ISO 9001
Quality Systems – Specifications for Design, Development and Servicing.
NORSOK M-101
Structural Steel Fabrication
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CPOC General Specifications
Reference
Title
CPOC-GS-GEN-0003
QA/QC Inspection and Testing
CPOC-GS-ST-0001
Offshore Structural Materials
CPOC-GS-ST-0002
Structural Steel Fabrication
CPOC-GS-ST-0005
Offshore Structural Welding and Inspection
CPOC-GS-ST-0009
Painting of Offshore and Coastal Structures and Facilities
3.0
GENERAL
3.1
Definitions
Reference
Description
Approval, approved
The authorization in writing given by the COMPANY to the
Contractor on a procedure or to proceed with the performance of a
specific part of the work without releasing in any way the Supplier
from any of his obligations to conform with the technical
specifications, requisitions, etc. The words “Approve”, “Approved”
and “Approval” shall be construed accordingly
COMPANY
CARIGALI – PTTEPI Operating Company Sdn Bhd (CPOC)
Contract Documents
The drawings, equipment lists, bills of material, material
specifications, etc., latest editions, issued by the COMPANY and
attached to the Contract or the Purchase Order
Contractor
The company designated on the Purchase Order form or Contract as
being selected for performing the fabrication work
Inspector
The COMPANY’s or Contractor’s representative(s), (as applicable),
or member(s) from an Inspection Agency duly appointed by the
COMPANY or the Supplier (as applicable) to act as its
representative(s) for the purpose of the contract
Manufacturer
PPS
The company or its sub-contractors selected by the COMPANY or the
Contractor (as applicable) as the Manufacturer of the said materials
Designates Project Particular Specification detailing the additional tests
and requirements or the possible modifications to the present
specification, based on the particular design conditions or the local
legislation of the structural project
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Description
Primary steel
Any structural member failure would cause total or partial platform
shutdown, but no total or partial destruction of the platform. Repair of
these members would only be made if operation or installation of the
platform is stopped
Purchase Order
The order issued by Purchaser consisting Terms and Conditions
and attachments thereto including but not limited to Data Sheets and
Drawings, Specifications including referenced documentation therein,
and all other documents and attachments
Purchaser
The COMPANY or the Contractor (as applicable) which have placed
the Purchase Order to the Manufacturer
Secondary steel
All structural members not classified as Special and Primary Steel
members, but contributing strength and stiffness to the platform
structure
Site
The yards, workshops, docks, laboratories or other locations where
the fabrication inspection and testing are to be performed complete or
in part, shall be referred to herein as the “Site”
Special steel
3.2
Doc. No.
Any structural member failure would cause total or partial destruction
of the platform during in-service operation or destruction of parts of
the platform during installation, or members that cannot be repaired
Tertiary steel
All steel members for accessory and finishing elements contributing no
stiffness and strength to the platform structure
WORK
All welding activities as define in the Scope of Work
Shall
Used to indicate that a provision is mandatory
Should
Used to indicate that a provision is recommended as good practice
May
Used to indicate that a provision is optional
Abbreviations
Reference
Title
AC
Alternating Current
ACI
American Concrete Institute
AFC
Approved For Construction
AISC
American Institute of Steel Construction
ANSI
American National Standards Institute
API
American Petroleum Institute
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Title
AS
Australian Standards
ASME
American Society of Mechanical Engineers
ASNT
American Society for Nondestructive Testing
ASTM
American Society of Testing Materials
AWS
American Welding Society
BS
British Standards
BSI
British Standards Institute
C
Carbon
CE
Carbon Equivalent
CSWIP
Certification Scheme for Welding and Inspection Personnel
CTOD
Crack Tip Opening Displacement
DAC
Distance Amplitude Correction
DC
Direct Current
DPT
Dye Penetrant Test
EMI
Electro Magnetic Inspection
EN
European Institute
FCAW
Flux Cored Arc Welding
FL
Fusion Line
FPSO
Floating Production Storage and Offloading
FPU
Floating Production Unit
GMAW
Gas Metal Arc Welding
GSFCAW
Gas Shielded Flux Cored Arc Welding
GTAW
Gas Tungsten Arc Welding
HAZ
Heat Affected Zone
HRC
Rockwell Hardness (C scale)
HS
High Strength
ID
Inside Diameter, identification
ISO
International Organisation for Standardisations
ITP
Inspection and Testing Plan
JIS
Japanese Industrial Standards
ksi
Kips per square inches
LPI
Liquid Penetrant Inspection
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Title
MDR
Manufacturers Data Report
MMA
Manual Metal Arc
Mn
Manganese
MPa
Mega Pascal
MPI
Magnetic Particle Inspection
MPS
Manufacturing Procedure Specification
MT
Magnetic Particle Testing
NACE
National Association of Corrosion Engineers
NDT
Non Destructive Testing
OD
Outside Diameter
PPS
Project Particular Specification
PQP
Project Quality Plan
PQR
Procedure Qualification Record
PS
Percentage of Strain
PT
Penetrant Testing
CGS
CPOC General Specification
PWHT
Post Weld Heat Treatment
QA
Quality Assurance
QC
Quality Control
QT
Quenched and Tempered
RA
Reduction Area
RP
Recommended Practice
RT
Radiographic Testing
SAW
Submerged Arc Welding
SI
International System (of Units)
SMAW
Shielded (Manual Metal) Arc Welding
SMYS
Specified Minimum Yield Strength
SSFCAW
Self Shielded Flux Cored Arc Welding
SSPC
Steel Structures Painting Council
STR
Structural
TIG
Tungsten Inert Gas
TL
Tightened Length
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Title
TMCP
Thermo-Mechanical Control Process
TOS
Top Of Steel
TPI
Third Party Inspection
TQ
Technical Query
TTP
Through-Thickness Plate
UOE
U-ing, O-ing and Expanding
UT
Ultrasonic Testing
UTS
Ultimate Tensile Strength
VI
Visual Inspection
WI
Welding Institute
WPG
Welded Plate Girder
WPQ
Welding Procedure Qualification
WPQR
Welding Procedure Qualification Records
WPS
Welding Procedure Specifications
WT
Wall Thickness
YS
Yield Strength
4.0
GENERAL WELDING AND INSPECTION REQUIREMENTS
4.1
General
4.1.1
Contractor shall provide qualified superintendents, engineers, technicians, surveyors
and labourers, tools, equipment and machinery, materials, quality assurance, testing, storage,
fabrication areas, loadout facilities, offices, laboratory, etc. necessary to carry out
qualification of welding procedures and welders, handling, fabrication, welding, inspection
and cleaning of the structures according to this specification.
4.1.2
Welding shall be in accordance with CPOC-GS-ST-0005, with the appropriate
references to ANSI / AWS D1.1, and Section 10 of API RP 2A unless otherwise indicated
in this specification.
4.1.3
Typical welding details (to be provided) shall be applicable unless otherwise specified by
COMPANY.
4.1.4
Welders shall be provided with individual portable ovens (heating quivers) for electrode
conservation during the work on site.
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5.0
WELDING CONSUMABLES
5.1
General
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5.1.1
This section shall be read in conjunction with CPOC-GS-ST-0001 “Offshore Structural
Materials”, CPOC-GS-ST-0002 “Structural Steel Fabrication” and the following paragraphs of
this specification
5.1.2
All welding materials provided shall be subject to inspection by the COMPANY
representative either at the mill, shop, or other work sites.
5.1.3
Inspection at the mill, shop, or fabrication sites will not relieve the Contractor of the
responsibility for furnishing welding materials that satisfy specification requirements.
5.1.4
Materials that do not conform to the requirements of this specification shall not be used.
Non-conforming materials may be rejected at any time at no cost to COMPANY.
Selection of Consumables
5.2.1
Consumables shall be in accordance with CPOC-GS-ST-0005 and shall conform to
ANSI/AWS D1. 1 and shall have been approved by an international recognized certification
body (e.g. DNV, LLOYD’s, etc.).
5.2.2
Welding consumables shall be selected to match or exceed the base metals toughness,
yield strength and tensile strength of the base material. If classification of the structure is
required, welding consumables shall conform to rules of the Classification Society.
5.2.3
Cellulosic electrodes are strictly forbidden for structural use.
5.2.4
Welds forming connections between steels of different grades of material shall develop
the minimum specified tensile properties of the lower steel grades being joined, unless
otherwise previously approved by the COMPANY.
5.2.5
Welds forming connections between steels of different grades of material shall develop
the minimum specified notch impact properties at the lowest temperature of steel grades being
joined, unless otherwise previously approved by the COMPANY.
5.2.6
For repair welding or multiple repairs, “extra low hydrogen” electrodes are required (i.e.
maximum specified hydrogen content of 5 ml per 100 gram of weld metal).
5.2.7
For welding castings or forgings, “extra low hydrogen” electrodes are required (i.e.
maximum specified hydrogen content of 5 ml per 100 gram of weld metal).
5.2.8
For SMAW process, coated electrodes shall have a minimum diameter of 3.15 mm on
Structural Steels.
5.2.9
The number of different consumables shall be minimized.
5.2.10 All consumable batches (lots) used in production shall be tested (for SAW, all flux
batches as well as wire batches are to be tested). Chemical analysis shall be performed
1
during this consumable qualification test, and all elements shall be tested.
Consumable batches shall be qualified at the very early stage (welding qualification or
advanced production test) in order to make sure of their quality at the very beginning of
the production. The test shall be carried out on butt weld on the highest grade steel
used for which the lots are used in production. One tensile test transverse to the weld
and a set of three Charpy V notch in weld metal at the lowest temperature for which the
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lots are used in production shall be carried out. Results shall meet the value of the
highest grade steel for tensile test and the minimum requirement for the highest grade
steel at test temperature for the Charpy test, according CPOC-GS-ST-0001.
In addition, consumables for CTOD materials shall also be subjected to CTOD testing,
1
where applicable.
5.2.11 Manual shielded arc welding electrodes shall conform to AWS A5. 1 or A5 .5 specifications
and be of low hydrogen classification E-XX1 5, E-XX1 6, and E-XX1 8 and be suitable for the
position and conditions of their intended use. All passes shall be made with E-70XX or higher
class electrodes.
5.2.12 Flux cored arc welding electrodes shall conform to AWS A5.20 specifications and be
suitable for low hydrogen welding. The electrode classification shall be E70T- 1, E70T-5, or
E70T-6, as applicable.
5.2.13 Flux and electrodes for submerged arc welding shall conform to AWS A5.17 specification.
The materials shall be used in accordance with the manufacturer’s recommendations
regarding temperature and humidity limitations. Flux shall be screened and filtered before
reuse. SAW fluxes shall be of the fully basic type and shall not be used to make alloying
additions to the weld metal.
5.2.14 Flux cored welding consumable shall have low hydrogen certified by batch basis.
5.3
1
Essential Variables
5.3.1
The following essential variables shall be used in addition to AWS D1.1, for qualification
of welding procedures. Any deviation from these variables shall require a new weld
procedure be qualified. All essential variable tolerances listed as percentage variations
apply to the actual qualified mean values recorded for each pass:
1)
An increase of more than 38 °C in the maximum interpass temperature.
2)
An increase in heat input or an increase in volume of weld metal deposited per unit
length of the weld, over that qualified. The increase may be measured by either of the
following:
a)
Heat input (Joules/inch) = Voltage x Amperage x 60 / Travel Speed
(inch/min.)
b)
Volume of Weld Metal = an increase in bead size or decrease in length of weld
bead per unit length of electrode.
3)
For impact testing and CTOD testing qualification welds made in 3G vertical
progression will qualify for all positions only with respect to impact and CTOD
provided the maximum electrode used in qualifying the vertical procedure is not
exceeded in other positions and heat input allowed in any other position is within the
range of heat input qualified by the vertical weld.
4)
Where CTOD testing is to be qualified as a part of welding procedure, job thickness
shall not exceed CTOD qualification Test thickness.
5)
Where CTOD testing is to be qualified as a part of welding procedure, separate tests
are required to qualify single and double-sided preparations where both are
appropriate to the work.
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5.3.2
For Welding procedures with impact / CTOD testing, heat inputs shall not exceed 3.5
kJ/mm for material grades 275 and higher.
5.3.3
Test pieces for welding procedure qualifications shall be in accordance with AWS D1.1
and this specification. Test pieces for procedure qualification of carbon steel, shall be
selected from the higher range of carbon equivalents.
For all types of steel, the carbon equivalent (CE and Pcm) shall be calculated base on
product analysis.
1)
When the carbon content is greater than 0.12 %, the following Carbon Equivalent
formula, shall be applicable.
2)
When the carbon content is 0.12 % or less, the following Carbon Equivalent formula,
shall be applicable.
Procedures shall be qualified for welding production materials with a CE or Pcm up to and
including 0.02% higher than the qualification test material.
Heat/ladle analysis may be used if approved by COMPANY when product analysis is not
reported. Use of higher CE or Pcm steels will require a new welding procedure
qualification.
5.3.4
Types of grooves and tolerances for drawing details and final fit-up of any welded joint
shall conform to figure 3.4 of AWS D1.1. Joints which vary from these shall be referred to
COMPANY for approval or correction. Root openings for single sided welds without
backing shall be ≥ 1/16in. (1.6mm).
5.3.5
Root and capping passes during qualification, shall be made at a preheat temperature
and heat input no higher than the lowest values specified for production welds.
5.3.6
Unless otherwise approved by COMPANY, interpass grinding shall not be used during
qualification test welding. Grinding is considered an essential variable and must be used
for field welding to the same extent. If used during procedure qualification, each welder
shall have access to his own grinder, and each pass shall be ground as demonstrated on the
qualification test.
5.3.7
A temper-bead sequence shall not be used during procedure qualification to
deliberately improve heat affected zone hardness. The final welding procedure cap pass
shall be placed along the side of the weld so as to overlap onto the base metal. Production
welds qualified may be made with or without temper beads.
CPOC
5.4
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Supply, Storage and Use
5.4.1
The minimum requirements for the care, storage and handling of consumables shall
be according to the manufacturer’s requirements. Welding materials shall be handled,
shipped, and stored in a manner that will prevent contamination by moisture, dirt, grease,
oil or any other debris or other damage. The temperature and humidity storage conditions
shall comply with the manufacturer’s recommendations. Electrodes and filler wires which
show evidence of damage or deterioration and shielding gases which show signs of
contamination shall not be used. Shielded metal arc welding electrodes shall be stored in
drying ovens in accordance with AWS D1.1. A detailed storage and handling procedure
shall be compiled by the Contractor and submitted to COMPANY for review/approval.
5.4.2
Welding materials shall be identifiable by means of their original colour coding or by
factory labelling until the time of use.
5.4.3
Welding electrodes that have damaged flux, are not readily identifiable, or are of
questionable acceptability, shall not be used.
5.4.4
Different grades of electrodes shall be stored separately.
5.4.5
Low hydrogen electrodes and fluxes shall be supplied in sealed moisture proof
containers. The unopened containers shall be stored in a dry location based on Filler
manufacturer’s recommendation with monitoring by Hygrometer or other means at all
times.
5.4.6
Each heat, lot (or so called batch herein) of consumables shall be subject to inspection
and approval by the Inspector. Mill test certificates from consumables manufacturers
showing test results actually obtained on the said lot shall be submitted to the Inspector.
5.4.7
The lot and the level of testing are specified as per AWS A5.01-93 as follows:
1) Covered electrodes: class C5
2) Bare solid electrodes and rods: class S3
3) Flux cored electrodes and metal cored electrodes and rods: class T3
4) Flux for submerged arc welding: class F2
5.4.8
The level of testing shall be schedule I as a minimum. Additional testing (diffusible
hydrogen test and/or moisture test shall be required as per attachment 2 of CPOC-GS-ST0001 for SAW flux when “specification A” is proposed.
5.4.9
For steel grades S355 and above (refer to CPOC-GS-ST-0001), SAW flux
procurement, packing, storage and use shall conform to requirements of Attachment 2 of
CPOC-GS-ST-0001.
5.4.10 Certificates of conformance are not acceptable. Batch testing of welding consumables is
required from Contractor in combination with production test plan.
5.5
Drying Procedures and Use of Electrodes
5.5.1
As a general rule, welding electrodes shall be treated and used in accordance with
recommendations of their manufacturers. In the absence of written recommendations from
the manufacturers of consumables, the requirements of AWS D1.1 shall apply.
5.5.2
Prior to use, as a minimum, basic low hydrogen consumables shall be dried by baking.
The baking temperature/time shall be that which is necessary to achieve minimum diffusible
hydrogen content of less than 10ml/100g of weld metal. Electrodes shall be transferred to
1
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holding ovens and heated quivers as necessary. Any electrodes remaining unused at the
end of a shift shall be returned to the store and re-baked before being re-issued. Returned
electrodes must be suitably identified to distinguish them from virgin electrodes.
5.6
5.5.3
The permissible atmospheric exposure of low hydrogen electrodes shall be two hours
max., unless shorter a time is required in AWS D1.1. Low hydrogen electrodes which have
been in direct contact with water shall be definitely rejected and removed from the Site.
5.5.4
The Contractor’s consumable procedure for storing, handling, drying, flux recycling and
traceability shall be approved by the Inspector before fabrication commences.
Substitution of Materials
The Contractor shall not make substitution of any material specified in the Contract Documents
without the prior written approval of the COMPANY.
5.7
Material Inspection and Storage
5.7.1
Contractor shall inspect all materials delivered to site. The welding consumables shall
be checked for compliance with delivery/packing lists, identification, quantity and damage.
5.7.2
Rejected welding consumables are to be quarantined in a separate location from the
accepted material.
5.7.3
All welding consumables receipt, handling and storage shall be performed in
accordance with the Contractor’s approved materials handling procedure.
6.0
QUALIFICATION OF WELDING PROCEDURE, PERSONNEL AND EQUIPMENT
6.1
General
6.1.1
Welding procedures, shall be qualified in accordance with AWS D1.1 and the requirements
as stated in this specification. Previously qualified welding procedures, welder or welding
operator qualification, witnessed by a third party certification agency such as ABS, Lloyds,
BV or DNV may be accepted as regard to the requirements of present specification (for
example, brand name and designation of consumables shall be clearly indicated in WPS
and WPQR, and Mill certificate of base material used for qualification tests shall be
included in the WPQR) and subject to prior review and approval of the COMPANY.
However, production tests where required (see paragraph 8.7) shall always be maintained.
In that case, the main weld of first tubular produced shall be subject to a full set of
production tests as per paragraph 6.3.10 of this specification.
6.1.2
Qualification of a welding procedure shall be restricted to the Contractor and Site where
the test weld was produced. However, in special cases, a welding procedure can be
extended to other Sites from the Contractor when the said Contractor gives evidence to the
satisfaction of the COMPANY that similar equipment and Quality Assurance system are
used and that his welding personnel (welders and welding supervisors) is of similar
competence and aware of the application of the said welding procedure.
6.1.3
A qualified welding procedure shall be used within the limitations of the essential variables
set forth in ANSI / AWS D1.1 and following amendments. Refer also to variables specific to
welding of tubular joints stated in Section 8.7.6 of this specification.
Any change from specifications stated herein shall initiate a new procedure qualification
test.
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6.1.4
Standard welding procedures which are covered in AWS D1.1 as pre-qualified WPS ’s
without any need for qualification tests, are not acceptable.
6.1.5
All structural welding shall be in accordance with AWS D1.1, Structural Welding Code –
Steel. Unless otherwise specified, in this specification or on the design drawings, all welds
shall be full penetration welds.
6.1.6
Acceptable methods of welding are SMAW, SAW, FCAW and GTAW processes. Gas
metal arc welding with the short circuit transfer mode (GMAW-S) is normally not
acceptable, however, the process may only be used with approval by the responsible
COMPANY representative and will only be approved for specific applications. GMAW is not
acceptable as the primary welding process, but may be considered for root passes if
completely removed or remelted by subsequent welding methods. GMAW may be used for
seal welding and for non-structural appurtenances with wall thicknesses 9.5 mm (0.375 in.)
and less
6.1.7
Welding procedure for longitudinal welds, circular welds (if any) and repair welds shall be
qualified as per ANSI / AWS D1.1 by means of visual examination (100 %),
nondestructive testing (100 %) and mechanical tests.
6.1.8
Tack welding shall be qualified as part of the welding procedure that governs the
connection.
6.1.9
If a procedure or welder produces excessive defects, the procedure and/or welder shall
be re-qualified. Costs associated with the re-qualification shall be borne by the Contractor.
6.1.10 Permanent back-up bars shall not be used.
6.1.11 For gas shielded process (e.g. FCAW, GTAW, and GMAW), windshield protection shall
be provided.
6.1.12 Should Post Weld Heat Treatment (PWHT) be required, Contractor shall completely define
the method of application in the welding procedures submitted. Consideration shall be
given to the possible reduction in material yield strengths resulting from any PWHT.
PWHT shall only be performed at the direction of the COMPANY.
6.1.13 “Downhill” welding shall not be allowed, without prior written approval of the
COMPANY.
6.1.14 Filler metals for welding, materials of different strengths and toughness, shall be required
to develop the strength of the lesser and toughness of the greater requirement.
6.1.15 At least four (4) weeks prior to commencing welding work, the Contractor shall submit
written welding procedures (WPS’s and PQR’s) and welding personnel qualifications for
welders and all welding intended for use during fabrication, previously qualified or
otherwise, to the COMPANY for approval. The documentation for each procedure shall be
in accordance with Section 10 of this specification.
6.2
Material Groups for Welding Conditions
Grouping of material qualities and pipe sizes may be made for certain welding conditions (e.g.
minimum, maximum heat input) subject to prior approval of the COMPANY. In such a case, the
following conditions shall apply to base materials:
6.2.1
Material grades with SMYS (Specified minimum yield Strength) greater than 355 MPa.
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Any steel with a minimum specified YS in excess of 355 MPa, i.e. S420, S460 and S500
steel grades as defined by CPOC-GS-ST-0001 shall require separate welding procedure
qualification test on the production material:
1) Per delivering mill
2) Per as-delivery condition
3) Per each steel grade
4) Per each steel quality (impact test requirements)
The validity of such a welding procedure qualification is moreover limited to materials of
the same grade as defined above considering the further restriction:
1) Carbon, Carbon Equivalent and Pcm of the test material is not less than 0.02%, 0.03
% and 0.02 % respectively, in comparison with the materials of the order
2) Welding consumables are considered as still acceptable in COMPANY’s opinion
6.2.2
Material grades with SMYS less than or equal to 355 MPa
Welding procedure qualification tests is required for steels corresponding to group I as
defined by AWS D1.1 , or any steels group II as defined by AWS D1.1, with SMYS less or
equal to 355 MPa, or any steel combination as defined by AWS D1.1.
The validity of such a welding procedure qualification is limited to materials of the same
group or steel group combination as defined above, considering the further restriction:
1) Per delivering mill (group II only)
2) Per as-delivery condition (group II only)
3) Per each steel quality (impact test requirements)
In addition, any welding procedure qualified as per above, will cover materials of the said
group provided that:
1) Minimum Specified YS does not exceed the SMYS of the qualified material by more than
60 MPa
2) Carbon Content, Carbon Equivalent and Pcm of the test material is not less than
0.02 %, 0.03 % and 0.02 % respectively, in comparison with the materials of the
order
3) Welding consumables are considered as still acceptable in COMPANY’s opinion
6.2.3
Unless otherwise agreed with the COMPANY, two weld repair types shall be qualified by
tests:
1) One partial repair (minimum of 2/3 thickness repair) simulating a defect located on
Fusion Line, and
2) One shallow cap repair with two weld passes minimum simulating a defect located at weld
toe (e.g. undercut repair)
Where welding from inside of pipe is not intended by the Manufacturer, nor practicable,
nor accepted by the COMPANY, then a through thickness repair simulating a defect
centered in Weld Metal axis shall also be required.
6.2.4
The following mechanical tests shall be carried out on each qualification test weld (main
and repair):
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1) Two tensile tests transverse to the weld. The ultimate tensile strength shall meet the
values shown in CPOC-GS-ST-0001
2) Two guided bend tests: one face-bend and one root-bend test, with weld
reinforcement removed from both faces, shall be carried out for wall thickness of 12.7
mm and less. For wall thickness above 12.7 mm, these tests shall be replaced by two
side bend tests
Specimens shall be full thickness with a specimen width of 12.5 mm. The mandrel
diameter for bending shall be as follows
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a) 2 t max. for grade S 235
b) 3 t max. for grades S 275 and S 355
(t = thickness of test specimen).
3) Three CHARPY V-notch impact test specimens transverse to weld cut on the
material surface in accordance with Figure 2 (notch in the Weld Metal axis, on the
Fusion Line, at 2mm and at 5mm from Fusion Line). Each impact test shall include
one set of three specimens (total of twelve specimens).
4) For tubulars in thickness above 50 mm, two additional sets shall be cut at weld root
as shown on Figure 2.
Locations of CHARPY V-notch test specimens in weld repairs shall be as shown on
Figure 2.
Impact tests shall be carried out at the same test temperature as that specified for the
related base material quality.
Impact test results shall meet the required absorbed energies stated in Table 5.3 of
CPOC-GS-ST-0001.
5) One macrography/hardness test: a VICKERS hardness survey shall be conducted
using a 5 kg load in accordance with Figure 1. No individual hardness value shall
exceed 325 HV on the Weld Metal and HAZ.
6) Shallow cap repairs shall include only side bend tests and hardness test as detailed
above.
Type of specimens for welds on plate can be referred to paragraph 6.4.2 of this
specification with the same of number of specimens as above.
6.3
Welding Procedure Specifications (WPS)
6.3.1
WPS shall be read in conjunction with CPOC-GS-ST-0002 and this specification. Each
welding procedure shall be fully detailed in a Welding Procedure Specification (WPS)
form previously approved by the COMPANY.
6.3.2
Four weeks prior to commencement of any welding, the Contractor shall submit to
COMPANY a weld register (i.e. a detailed summary table) of all the WPS he intends to
use, together with all the said WPS in their complete form. The weld register shall detail
the characteristics and scope of use of each WPS.
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6.3.3
WPS shall be produced for production welds (i.e. main welds), repair welds of main welds
and base materials, weld buttering, wide gaps, etc.
6.3.4
The minimum acceptable WPS shall include, at least, all items listed below:
1)
The identification of base metals ( relevant Mill certificates to be valid for the
applicable range)
2)
The qualified range of base materials in terms of steel grade, thickness, CE and/or
Pcm, diameter, etc.
3)
The welding process
4)
Design and dimensions of joint preparation, including tolerances
5)
Welding position(s)
6)
Direction of welding
7)
Type, size, AWS classification, manufacturer and trade name of welding electrodes,
filler wires, shielding fluxes and gases. Gas mixture compositions
8)
Type, amperage and voltage range of welding current
9)
Travel speed, heat input (in kJ/mm) and wire feed speed when applicable. Number
and distribution of weld runs related to each electrode or filler wire, specially for
capping
10) Stick-out length, when applicable
11) Thickness (or depth) of tack weld, specially when SAW is used
12) Mini preheating, min. and max. interpass temperature
13) Post-heating and Post-Weld Heat Treatment conditions, if any
14) Treatment to second side of weld including depth of backgouge / backgrind
15) The reference to the applicable Welding Procedure Qualification Record (WPQR).
6.3.5
There shall be no more than 3 WPQR to support a single WPS.
6.3.6
New WPS shall be issued first as “proposed WPS” (P. WPS), then as WPS “approved for
construction” (AFC) and any WPS revision shall be issued with sequential numbers and
date of issue. All forms shall have prior approval of the Inspector.
6.3.7
The approved WPS shall be posted permanently at the location where the welding is to be
performed and readily available to each welder and welding operator
6.3.8
A procedure for repair of wide gaps shall be included. This procedure shall be in
accordance with AWS D1. 1 and this Specification
6.3.9
When weld through primers are used during fabrication, they shall be included in the weld
procedure qualification. During weld procedure qualification, the thickness of weld through
primer shall be measured. Any increase in thickness of primer in production, shall
necessitate re-qualification of the affected Procedure Qualification Record (PQR).
6.3.10 Each applicable WPS shall be qualified by tests prior to commencement of the work as
directed by the ANSI / AWS D1.1, and the requirements of this specification
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Welding Procedure Qualification Tests
6.4.1
All welding procedures shall be qualified in accordance with AWS D1.1 except as
modified by this specification. In addition to applicable Code requirements, procedure
qualification for fillet welds not qualified by full penetration butt welds, shall include a
hardness test and meet the requirements of this specification.
6.4.2
Welding procedure qualification for plates and tubulars (except tubular nodes)
1) The essential variables as stated in paragraph 5.3 of this specification shall apply.
2) Type and number of tests are stated in paragraph 6.2.4 of this specification.
a) Butt welds on plates and tubulars
See sampling of test specimens in Figure 3 for plates and in Figure 4 for tubulars
b) T or Y groove welds on plates
See sampling of test specimens in Figure 5
c) Fillet W elds
Fillet welds shall require separate qualification tests (groove welds cannot qualify
for fillet welds). One test shall be made with minimum size single-pass fillet weld and
another test weld shall be made with the minimum size multiple-pass fillet weld
used in construction.
When Fillet Welds are subject to Welding Procedure Qualification Test (see
paragraphs 6.4.17 and 6.4.18 of this specification), the test weld shall be sampled
for macrosection examination and hardness survey as follows:
i)
For plates and tubulars: sampling as per AWS D1.1, Table 4.4.
ii) Testing procedures and standards of acceptance shall be as described in
paragraph 6.4.22 of this specification.
6.4.3
The thickness ranges of material qualified by a certain welding procedure shall be as per
table 6.1 below. Thicknesses are indicated in terms of Reference Thicknesses (T) as
defined as follows:
1) In a butt connection the Reference Thickness is the thickness of the steel plate.
2) For butt welds at blended transitions between plates or tubulars of different
thicknesses the Reference Thickness is that of the thinner part.
3) For welds not of straight butt configuration (e.g. stub to can welds or ring stiffener to can
welds) the thickness of the abutting members (e.g. stub thickness or ring stiffener thickness)
shall be the Reference Thickness.
4) In the particular case of weld between crown shims and jacket piles, the Reference
Thickness shall be that of the jacket piles.
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Table 6.1 - Range of Thickness (T) Qualified for Complete or Partial Penetration
Groove Welds and Fillet Welds Made on Plates and Pipes
Tested WT (inches)
Qualified WT (inches)
1/8”≤ T < 3/8”
1/8” to 1/2”
3/8”≤ T < 1”
T/2 to 1.5T
1” ≤ T< 2”
3/4” to < 2” (less than 50mm)
T > 2”
2“ (50mm) and above
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Where the applicability of the WPS is based on fracture mechanics testing (e.g. CTOD) the
upper thickness deviation shall not exceed the smaller of + 10 % and + 10 mm in regard to
the tested thickness.
6.4.4
The OD ranges for welding procedure qualification of tubulars are as follows:
1) 2” ≤OD< 12”
2) 12” ≤OD< 24”
3) OD ≥ 24”
Qualification on plate also qualifies for pipe 24” and over in diameter.
Qualification on pipe 24” and over in diameter also qualifies for plate.
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Qualification on pipe below 24” does not qualify for plate.
6.4.5 Joint Configuration
Change from butt welds to T-joints and Tubular Joints, and vice versa. Single-V may
qualify for double-V welds and vice versa, provided that there is no decrease in groove
angle. Any change with respect to back gouging, back pass, temporary or permanent
backing.
6.4.6
Groove design/Pass distribution
As per AWS D1.1 and the following:
1) Any decrease in groove angle, root opening. Any increase in root face
2) Capping passes, hot pass(es) and back passes must be distributed as per the agreed
WPS
3) A particular procedure must be developed and qualified by test for wide gap welds.
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Maximum thickness of buttering qualification shall be 12 mm (refer to CPOC-GS-ST0002) and maximum weld deposited shall be as per paragraph 7.7.3 of this
specification.
6.4.7
Welding process/Heat input
Any change from one welding process(es) to another process(es) and any mixing of
processes. Any change of heat input beyond ± 10 %.
6.4.8
Welding consumables
Any change of specified consumable in trade name, classification, source of origin, size or
combination.
6.4.9
Welding positions shall be as per limitations contained in AWS D1.1: 2000, Table 4.1,
except that groove welds cannot qualify for fillet welds.
6.4.10 Welding direction
A change shall be from vertical down to vertical up welding and vice-versa.
6.4.11 Orientation of tubular joints
Any change between the following orientations:
1) Can fixed vertical, brace fixed inclined
2) Can fixed horizontal, brace fixed vertical
3) Can fixed horizontal, brace fixed horizontal
6.4.12 Stub to can angle of tubular joints
Stub to can angle is defined as the angle between the centerlines of stub and can.
Table 6.2 - Stub to Can Angles
Stub to Can Angle of WPQT
Angle Range Qualified
α > 45°
-0°;+90°
30° ≤ α ≤ 45°
-0°;+120°
α < 30°
-0°;+130°
6.4.13 Preheating/interpass temperature
Any change outside -0°C, +25°C from that of qualification test
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6.4.14 Post Weld Heat Treatment (PWHT)
Change from Post Weld Heat Treatment to non-Post-Weld Heat Treatment and vice versa.
Any change outside specified temperature range, soaking time and cooling/heating rates.
6.4.15 If joint fit-up tolerances in production welds exceed those permitted, written weld buttering
instructions shall be developed by Contractor for COMPANY approval. These shall detail
the complete base material preparation, welding, surface finishing, and inspection methods.
Welding must comply with a COMPANY approved WPS.
6.4.16 AWS D1.1 limits on qualified thickness ranges, shall be followed except where it allows an
unlimited maximum thickness. In those cases, a limit of 2T maximum shall be applied,
where T is the wall thickness of the test coupon.
6.4.17 Pre-qualified welding procedures as defined in ANSI / AWS D1.1 may be used without
qualification test subject to prior approval by the COMPANY
However, such procedures shall meet the requirements of this specification and shall be
restricted to members which simultaneously meet the following conditions:
1) Secondary Category Structural Members or Non-Structural members
2) Specified yield strength does not exceed 262 MPa (38,000 psi)
3) Base metal wall thickness is less than 19.05 mm (0.750 in.).
6.4.18 Fillet welds made by SMAW processes are not subject to welding procedure qualification
test when base material involved complies with the following requirements all together:
1) Primary or Secondary Category structural members or Non-Structural members
2) Specified yield strength does not exceed 262 MPa (38,000 psi)
3) Base metal wall thickness is less than 25.4 mm (1 in.)
4) IIW Carbon equivalent does not exceed 0.40 % (ladle).
Reference shall be made to weld and welding requirements contained in paragraph 7.9 and
7.10 of this specification.
6.4.19 The Welding Procedure Qualification Test shall be witnessed by the Inspector and
carried out under actual or simulated conditions, based upon the proposed Welding
Procedure Specification (WPS).
1) Selection of test base material
Welding procedure qualifications shall be carried out on test coupons with their
Carbon Equivalent (CE), Pcm and Carbon content, in the upper limits of the materials
supplied and, anyway, as per requirements on chemistry as stated in paragraphs 6.2.1
and 6.2.2.
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The chosen coupon shall be completely identified by Mill Certificate showing its ladle
and product chemical composition and mechanical properties.
2) Type and number of tests
The qualification of welding procedures shall be based upon visual inspection, nondestructive testing and mechanical testing.
Type and number of tests shall be as specified in paragraph 6.2.4.
Reference is made in this specification to paragraphs 6.4.2 and 6.4.23 for sampling of
specimens and to paragraph 6.4.22 for testing procedures and standards of
acceptance.
6.4.20 Welding on forgings and castings shall be qualified by special tests. Welding coupons
shall be used. Test programme shall be submitted for COMPANY acceptance and may
content complementary test than those defined hereafter as CTOD or fatigue tests.
Tests programme shall be driven by calculation note and criticality of structure
6.4.21 Acceptance Criteria for Welding Procedure Qualification Tests
The completed weld shall be evaluated by the following in accordance with the acceptance
criteria of AWS D1.1 and this specification:
1) Visual inspection
2) Radiography (ultrasonic examination when specified by COMPANY
3) Mechanical tests per AWS D1. 1 and this specification
6.4.22 Mechanical Testing Requirements
The additional requirements described below will supplement AWS D1.1 requirement.
Mechanical testing shall be carried out by a COMPANY approved testing laboratory and
witnessed by COMPANY representative.
1) Hardness Test
For all weld procedures, the maximum hardness shall be determined using Vickers
hardness tests (ASTM E92). The test load shall be less than or equal to 5 kg.
Maximum acceptable hardness shall be 325 HV5. Hardness tests shall be carried out as
shown in Figure 1. If any individual hardness value exceeds the limit specified, further
hardness readings shall be taken at the same location, to check for consistency and
confirm the presence of high unacceptable hardness. If it is proven to be
unacceptable hardness, the welding procedure needs to be modified and re-qualified.
One weld area sample (including weld, HAZ, and parent metal) shall be ground,
polished, and etched with a suitable etchant so as to clearly reveal the weld metal,
fusion line, and HAZ microstructures under the microscope.
Rockwell and Brinell hardness tests are not acceptable. Conversions from Rockwell or
Brinell hardness tests are not acceptable.
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A photograph or photo macrograph of 1X to 5X magnification clearly showing the
hardness indentations, HAZ, and the weld zone shall be included in the test results.
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2) Charpy Impact Test
Unless otherwise specified, butt joint welding procedure qualification tests for
material S355 and above shall also include Charpy V notch impact testing in
accordance with ASTM A370. Impact testing shall cover Weld metal, Fusion Line and
HAZ. Minimum acceptable average values for all weld procedures shall be 27J for 35
Ksi Steel, 36J for 50 Ksi Steel and 45J for 60 Ksi steel at minus 20 °C for all thickness.
The location of weld, fusion line and HAZ Charpy testing specimens shall be in
accordance with Figure 2.
If two or more welding consumables or welding processes are used for the same
joint, impact testing is required for the related regions of the welded joint
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1
3) Crack Tip Opening Displacement Tests (CTOD)
a) CTOD testing of welds, is required as a part of Welding procedure
qualification tests, when the job thickness is 50mm and above for material S355
and above. The CTOD tests shall be carried out using maximum thickness
encountered during fabrication as per the essential variables of AWS D1.1 and this
specification.
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b) All costs associated with the test program shall be borne by the Contractor
c) The test welds shall be tested in the as-welded condition by CTOD testing to BS
7448 Part 2 in the weld.
d) Test plates shall be of dimension 1.5m x 0.35m minimum and weld
preparation shall be such that the joint contains one square edge.
e) An all weld metal tensile test shall be conducted as a part of welding procedure
qualification test and actual weld yield stress shall be used for computing CTOD.
f) For each test the least of the values of δc, δu or δm shall be greater than or
equal to 0.25 mm when tested at 0°C. Where welds are required to achieve values
greater than 0.25 mm, the required values will be indicated on the relevant
drawing. Lower values require approval by COMPANY on a case by case basis.
g) All CTOD test results together with CTOD record traces including all failures shall
be reported and submitted to COMPANY for review.
h) Where the specified values cannot be achieved, the Contractor may submit for
review, after consulting with COMPANY, justification of the lower values achieved
using the “fitness for purpose criteria” of BS 7910.
i)
Material grade S355 and above shall be tested to API RP 2Z in the mill, Testing
shall be conducted on the thickest plate supplied.
j)
Test welds for each welding process to be used in production, shall be
performed by the Contractor. Heat inputs used shall be representative of the highest
to be used in production. Mechanical testing shall consist of three CTOD tests
from each type of weld metal. Testing will be to BS 7448 Part 2 using the validation
criteria specified in EEMUA 158.
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k) The steel supplied used for the qualification tests, shall be representative of the
steel supplied in the bulk order in terms of chemistry, manufacturing route and heat
treatment.
6.4.23 Welding procedure qualification for T, K, Y tubular node joints
1) Qualification tests shall be as per AWS D1.1 Latest edition with the modifications
stated hereafter. Qualification tests shall include both a tubular butt weld in 6 GR
position with a 1/2 V bevel design and a tubular mock-up. Limitations on qualified
welding procedures shall be as per paragraphs 6.4.3 through 6.4.14 of present
specification, especially regarding brace thickness and diameter ranges, orientation of
tubular joints and brace to can angle. Testing of the butt weld shall be made as per
paragraph 6.4.2 for a regular butt weld including impact tests. Testing of the tubular
mock-up shall include 100 % UT and macrographies as required by AWS D1.1, each
being subject to a hardness survey.
2) Brace to can angles less than 30° shall require a separate qualification test at the
minimum angle of the work (refer to AWS D1.1 Latest edition).
6.5
Qualification of Welding Personnel
6.5.1
Welders and Welding Operators shall be qualified in accordance with AWS D1.1 except as
modified by this specification. This qualification is at the Contractor’s expense.
Qualification on production welds shall not be allowed.
6.5.2
Qualification or re-qualification of welders by tests shall be required at the start of
construction or fabrication on each Site, unless otherwise previously agreed with the
COMPANY.
6.5.3
All welders working at construction yard shall be qualified in 6 G or 6 GR position, as a
minimum. The Contractor shall ensure that welders and welding operators of any subcontractor are qualified in accordance with this specification. All tubular joints and critical
welds, such as those on lifting lugs, shall be made by welders qualified for position 6GR.
6.5.4
Welder qualification tests shall be witnessed by the Inspector. When a qualification test is
performed between pipe to pipe without back pass, pipe ends shall be closed during
performance of test.
6.5.5
In addition to the tests required by AWS D1.1 and this specification, welder qualification
for any portion of the test made by GMAW-S (short circuit metal transfer) shall include
guided bend specimens. Qualification of GMAW-S by radiography only, is not permitted.
6.5.6
Manual welders and welding operators who have successfully carried out a Welding
Procedure Qualification Test shall be considered as qualified for the said procedure.
6.5.7
Contractor may submit evidence of previous qualification to COMPANY in accordance
with the minimum requirements of this specification. All previously qualified welders and
welding operators shall comply with the standard period of effectiveness covered in AWS
D1.1. For welders without prior experience on COMPANY work, re-qualification and
witnessing by COMPANY representative may be required.
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6.5.8
Welder Qualification Register and Welder/Welding operator performance qualifications
shall be made available for review and approved by COMPANY. Qualifications shall be reendorsed every 6 months by the Contractor.
6.5.9
Welder and welding operator qualification tests shall be conducted prior to the
performance of any production welding. Qualification test records shall be submitted to the
COMPANY for approval before the welder is permitted to work on the project.
6.5.10 The decision of the COMPANY regarding the qualification of any welder shall be final.
The COMPANY retains the right to require re-testing of any welder or welding operator at
anytime and be at Contractor’s expense.
6.5.11 Welder’s qualification test record specifying applicable WPS, essential variables and
providing the welder’s identification symbol.
6.5.12 Each qualified welder shall be assigned an identification symbol, and a record shall be
kept of these symbols by the Contractor. Two (2) copies of the symbol record shall be
submitted to the COMPANY.
6.5.13 The Contractor shall implement a system to monitor welders’ and welding operators’
performance. Any welder or welding operators whose weld reject rate exceeds the
maximum limit of 3% linear length per week, based on radiography and/or ultrasonic, shall
be removed until retrained and re-qualified. Re-testing shall be limited to two (2) re-tests.
The welding performance records shall be submitted to COMPANY on a weekly basis.
6.5.14 Qualified welders and welding operators shall be subject to additional training and/or
requalification test when the quality of their work, during fabrication, appears to be
repeatedly defective. The Inspector reserves the right to disqualify a welder.
6.5.15 Repairs are permitted during qualification test provided that they are of small extent
and infrequent. Numerous repairs shall be considered as sufficient cause for rejection of
the welder. The time spent for performance of the weldment should be comparable to regular
production conditions.
6.5.16 Identification of welders The Contractor shall assign a specific identification symbol or
number to each qualified welder. It shall be the duty of each welder to mark each weld on
which he works. In the event that a welder leaves the project his symbol or number shall
be cancelled, thereby ensuring that it is not re-used for any other welder. Each qualified
welder shall carry a badge with photograph, identification number, work qualification and
date qualified.
6.5.17 Welder Qualification for T, K, Y tubular joints
1) To be as per 6 GR of AWS D1.1. However, the test pipe shall be min. 8” OD and 12.7
mm WT, and the restriction ring shall be min. 12” wide.
2) Testing to be performed: Visual inspection, full RT and/or side bend tests cut at 3, 6, 9
and 12 o’clock position, at COMPANY’s option.
6.5.18 Visual examination and Non-Destructive Testing All test welds to be 100 % visually
examined and 100 % inspected by ultrasonics (or radiography, when applicable) before
any mechanical specimen is removed.
6.5.19 Mechanical testing for WPQ According to ANSI / AWS D1.1 for all kinds of welds, including
fillet welds.
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6.5.20 Testing procedures and standards of acceptance Preparation of specimens, testing
procedures and standards of acceptance shall be as follows:
1) Mechanical tests (other than macrographs): as per ANSI / AWS D1.1
2) Macrographs (when required): as per AWS D1.1
3) Visual inspection and non-destructive testing: as per Section 8 of this specification.
If one of the test joints does not meet the requirements, the welder or welding operator may
carry out at COMPANY’s discretion two new test joints of the same type as the rejected
one. If both these joints meet the specification requirements the test will be considered
satisfactory. If not the test the joints will be considered fail. A welder or welding operator so
failed shall not be permitted to retest until he has completed a period of retraining of one
week minimum.
6.5.21 Welder Qualification Record.
A record of the results of each qualification test weld shall be jointly signed by the
Contractor and the Inspector. The record shall indicate the symbol or number given to the
welder for identification of his work, as stated in paragraph 6.5.16 above of this
specification.
6.5.22 List of qualified welding personnel
A list of qualified welders and welding operators shall be established by the Contractor and
furnished to the Inspector before the beginning of fabrication. The minimum written
information included in this list shall be:
1) Contractor (name and address)
2) Name of each qualified welder or welding operator
3) Photograph
4) Date and place of birth
5) Symbol used by each welder or welding operator
6) Date of qualification
7) Type and extent of qualification obtained by each welder or welding operator
(position, welding process, etc.)
This list shall be kept up to date by the Contractor and made available to the Inspector.
6.6
Welding Equipment
6.6.1
Condition of Equipment
1) Welding machines shall have adequate controls for making the current adjustments
necessary for all welding requirements. Sufficient meters, portable or permanent shall be
provided to calibrate machines and to regulate voltage and amperage as needed. All
welding machines shall be calibrated prior to commencement of fabrication and calibration
certificates shall be available for audits. Certification shall be valid for 6- month periods,
or as per manufacturer’s recommendation.
2) To ensure the production of sound welds, welding machines, line-up clamps,
beveling machines, cutting torches, tools, supplies and other used equipment shall be
kept in good mechanical condition.
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3) Adequate number of suitable meters, portable or permanent types shall be provided
for calibration of the machines and to regulate amperage and voltage as needed.
6.6.2
Grounding of Equipment
Grounding of welding machines shall be in accordance with API RP 2A Section 12.7, with
the following additional requirements:
1) Each welding machine shall be individually grounded to the platform or portion of the
platform being welded to prevent underwater corrosion damage. If this is not possible,
the welding machine should be insulated from the barge and an adequately sized cable
shall be used to ground the structure to the welding machine.
2) Earth cable shall at least be of equivalent capacity to the work cable. The welding
cable shall be completely insulated to prevent stray currents.
3) When working over water such as offshore installation, no welding machine shall be
grounded to floating equipment during welding work on the structure and cables shall not
be allowed to hang in water.
4) Grounding several welding machines by a common ground cable which connects to
the structure being welded will control stray currents if adequately sized and properly
insulated from the barge or vessel where the welding machines are on.
5) Lugs for grounding cable shall be tightly secured to grounding plates:
a) The lug contact should be thoroughly cleaned to bare metal
b) One or more cables connected in parallel may be used to meet minimum cross section
requirements
6) Ground clamps for tubulars shall be designed to prevent arcing. The ground clamp
connection shall be steel.
7) Ground straps with an adequate cross section for carrying maximum possible short
circuit current shall be installed between jacket and pile or conductor while making
splices
7.0
PRODUCTION WELDING
7.1
General Requirements
7.1.1
All weld bevels shall be prepared by thermal cutting and grinding or by machining to a
smooth, bright uniform surface. Surfaces inaccessible to grinding shall be abrasive blasted
to near white metal with subsequent removal of all abrasive and residue near the weld
groove.
7.1.2
Design of butt weld groove preparations and assembly tolerances shall be in
accordance with AWS D1.1 and the approved welding procedure specification/drawings.
For single sided full penetration SMAW welds, the root opening shall not be less than 3mm
and not greater than 5mm.
7.1.3
Seal welding and welding of temporary attachments (including scaffolding supports and
tie-downs) shall be performed in accordance with the approved welding procedures.
7.1.4
Welding shall proceed in a manner that minimizes residual stresses or distortions. The
finished structure shall be as free from distortion as possible.
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The Contractor shall be responsible for preventing or correcting distortion and for
maintaining alignment within the tolerances stated in this specification. If excessive
distortion becomes evident, corrective methods shall be applied based on COMPANY
approved procedures.
7.1.5
All single-vee (‘V’) and single bevel butt welds shall be welded from both sides where
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access permits.
7.1.6
When more than one weld pass is deposited on a joint, each pass shall be thoroughly
cleaned by wire brushing and chipping before the next pass is applied
7.1.7
Welds shall not be quenched or cooled other than by contact with the natural atmosphere.
Welds shall be protected from rapid cooling caused by rain, wind, or other inclement
weather.
7.1.8
Surfaces of metal to be welded shall be free of fins, tears, cracks, loose scale, slag, rust,
oil, paint, and other defects or contaminants that would adversely affect the quality or
strength of the weld.
7.1.9
Welded areas shall be made clear of grease, spatter, flux and slag prior to application
of protective coatings.
7.1.10 Permissible atmospheric exposure time limits for low hydrogen shielded metal arc welding
electrodes shall be as set out in AWS D1.1, Table 5.1 Column A.
Alternate extended exposure time periods, whether established by test or not, shall not be
allowed.
7.1.11 All welded joints to be subsequently covered by an abutting member weld shall be
accepted by NDE prior to fit-up or welding of the covering member.
All plate butt welds that will be subsequently covered by an abutting weld shall be ground
smooth on the attachment surface for a minimum distance of 50 mm either side of the
intended attachment. A gradual transition shall exist between the ground and unground
areas of welded joint.
7.1.12 Welding may not be performed when, in COMPANY inspector’s judgment, the quality of
the completed weld would be impaired by the prevailing weather conditions. These
conditions include, but are not limited to, airborne moisture, blowing rains, or high winds.
Detailed plans shall be established to provide the welder and weld area with protection
during periods of inclement weather and/or excessive wind conditions.
7.1.13 Production welding may commence when qualified welding procedures and welders as
well as welding repair procedures and inspection procedures have been approved by the
Inspector.
7.1.14 Conditions of welding (preparation for welding, types and sizes of electrodes, current
amperages and voltages used, preheating requirements, etc.) shall be the same for
production welding as those defined in the applicable qualified welding procedures.
7.1.15 Adequate precautions shall be taken and suitable equipment shall be available on Site
in order to protect the weld areas and welders from adverse weather conditions (rain, wind,
snow, etc.) at the time of welding. The shielding of the welding sites shall be approved by
the Inspector prior to welding.
7.1.16
Welding shall not be done on wet weld areas. Wet weld surfaces shall be thoroughly
dried by preheating.
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Welding shall be stopped when the temperature of base metal is less than -10 °C.
Between -10 °C and +5 °C, the base metal shall be preheated to an approved temperature
before welding starts.
7.1.18 The Contractor shall provide the COMPANY, on a weekly basis, with the defect rate per
each welding process used and each NDT method (RT and UT), as well as the
subsequent cumulative defect rates for the same.
7.1.19 The Contractor shall develop the following documents in due time:
1) Weld maps
2) Welding sequences for main or critical component/construction
7.1.20 Use of temporary or permanent backing strip or inserts shall not be permitted, unless
specifically agreed with the COMPANY and, subsequently, properly qualified by test.
7.2
Welding Processes
7.2.1
Only manual Shielded Metal Arc Welding (SMAW) and automatic Submerged Arc
Welding (SAW) processes shall normally be used.
The welding process for longitudinal seams and circular welds (if any) shall be confined to
the automatic Submerged Arc Welding (SAW) process.
7.2.2
Semi-automatic Gas Metal Arc Welding (GMAW) shall not be permitted for any structural
categories even for tack welding excepted when totally removed with SAW process on X
bevels.
7.2.3
Automatic Gas Metal Arc Welding (GMAW) shall be subject to COMPANY approval on a
case to case basis. Gas Metal Arc Welding (GMAW) process may be used for tackwelding only provided that the weld is completely remelted by the Submerged Arc Welding
process.
7.2.4
Flux-cored wire (i.e. FCAW-GS) shall be subject to COMPANY approval on a case to case
basis. Flux Cored Arc Welding process without shielding gas (i.e. FCAW-SS) may be
approved (according to member Category) provided that the Contractor gives evidence of
long successful practice of the process in previous similar jobs to the satisfaction of the
COMPANY.
7.2.5
Only Extra Low Hydrogen processes (max. 5 ml H2/100 g) shall be used for welding and
tack welding of Special and Primary Category members or materials having specified YS
above 262 MPa (38,000 psi). The same requirement shall apply for any welding on
castings and forgings.
7.2.6
For Second Category members and Non-Structural members, welding processes other
than Extra Low Hydrogen processes may be used, subject to prior approval by COMPANY, for
materials having specified YS up to 262 MPa together with thickness up to 12.70 mm
(0.500”).
7.2.7
The number of different welding processes shall be minimized.
7.2.8
Different welding consumables qualities (basic extra low, basic low,) in a same type of
consumables shall be avoided.
7.2.9
Weld repair shall be carried out by SAW process or manual Shielded Metal Arc Welding
(SMAW) process using extra-low hydrogen electrodes (i.e. max. specified diffusible
hydrogen content of 5 ml per 100 g of weld metal).
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Base Metal Preparation
7.3.1
Surfaces to be welded shall be visually examined and must be cleaned to bright metal for
a distance of not less than 12.5 mm from the edge of the weld grooves. All surface finish
paints, including weldable primers, shall be removed from the weld groove when welding
pre-painted materials.
7.3.2
Welding through “weldable primer” is acceptable provided the weld procedure used is
qualified using the specific thickness and type of primer and provided the contract
documents allow the use of weldable primers.
Cutting and Edge Preparation
7.4.1
All sheared or gas cut edges shall be ground and visually examined for laminations,
cracks, and other defects. Sharp edges shall be removed by grinding.
7.4.2
For fabricated beams, all web and flange plates shall be cut such that the principle
rolling direction of the plate lies along the longitudinal axis of the finished plate girder.
7.4.3
Trimming tubular braces in-situ for closed root openings is not acceptable without specific
approval by COMPANY.
7.4.4
Tubular ends
Tubular bevels will be defined by the Contractor in compliance with the approved WPS.
When tubulars are intended to be butt welded to other tubulars of smaller wall thickness in
further fabrication, a taper of 1 to 4 shall be made to allow a proper fitting.
7.5
7.4.5
Surfaces and edges to be welded shall be smooth, uniform and free from fins, tears,
cracks, laminations or other defects which could adversely affect the quality and strength of
the weld.
7.4.6
The surface of chord members to be full penetration welded for T, K or Y joint (including
temporary or permanent attachments) such as tubular joints, padeyes, supports, etc.,
shall be ultrasonic (UT) inspected prior to welding for incoming members with thickness
greater than 25 mm.
7.4.7
The chord of tubular joint shall be properly rotated to avoid welding on tubular seams or
areas containing lamellar discontinuities.
7.4.8
Plates with lamination found during cutting, forming or welding shall be examined by
Ultrasonics Test (UT).
7.4.9
Any welding repair to be made on base material or beveled shall be subject to qualification
test.
Welding Sequences
7.5.1
The sequences for assembling, joining and welding the various parts of the structures
shall be planned in order to minimize distortion, warpage, shrinkage and accumulations of
residual joint stresses in each part of the structures (see para. 8.6 of this specification).
7.5.2
Joints expected to have significant shrinkage should usually be welded before joints
expected to have lesser shrinkage. They should also be welded with as little restraint as
possible.
7.5.3
In making welds under conditions of severe shrinkage/restraint, the welding shall be
carried out continuous to completion or to a point that will insure freedom from cracking
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before the joint is allowed to cool below the minimum specified preheat and interpass
temperatures.
7.5.4
7.6
The Contractor shall provide and exert all necessary supervision to ensure that the
planned sequences are observed.
Tack Welds
7.6.1
All tack welds, originally performed to hold members in alignment and later incorporated
into the completed weld, shall be carried out in the same conditions as the root pass of the
applicable qualified welding procedure and shall be performed by qualified welders.
7.6.2
These welds shall be subject to all applicable structural welding requirements in this
specification.
7.6.3
Tack welds shall be of sufficient cross-section and length to avoid cracks, especially on
High and Extra High Strength Steels materials (i.e. minimum specified YS above 295
MPa).
Tack welds shall be of a minimum length of:
1) Three times the plate thickness or 40 mm, whichever is the lesser, for steels with YS up
to 295 MPa
2) Four times the plate thickness or 75 mm, whichever is the lesser, for steels with YS
above 295 MPa.
7.7
7.6.4
Prior to continuation of welding, the “tack” weld shall be ground to a feather edge to
permit acceptable weld metal tie-in. Tack welds which form part of the complete weld shall be
ground to a feather edge and completely fused with the root run.
7.6.5
Cracked tack welds shall be completely removed and shall not be incorporated into the
finished weld.
7.6.6
Tack welds shall have the same preheat requirements as the root pass of the
appropriate structural welding procedure.
Correction of Unacceptable Fit-ups
7.7.1
Buttered layers on removed branch members shall be ground to the desired profile
and shall be subject to 100% visual, magnetic particle examination and ultrasonic
examination prior to refitting into the structure.
7.7.2
Correction of excessive root gaps by in-situ buttering is acceptable provided the gap is
greater than or equal to 6.4 mm. A COMPANY approved buttering procedure is required.
7.7.3
Any in-situ buttering shall require specific approval by COMPANY. The maximum weld
buttered deposit thickness shall be limited to 9.5 mm unless approved otherwise by
COMPANY.
7.7.4
Out-of position brace buttering shall require COMPANY approval.
7.7.5
Whenever practicable, clamps, magnets, holding devices, etc. shall be used to avoid
tack welding in assembling structural members. In fit-ups where clamps cannot be used,
spacer strips will be employed to ensure the correct root gap spacing prior to tack welding.
Spacer strips shall not be welded into the joint.
7.7.6
When misalignment between faces of parallel members of equal thickness not indicated
on drawings exceeding 10 % of the thickness, nor 3 mm shall be corrected to improve the
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misalignment. The correction shall be carried out using adequate mechanical means.
Heating shall not be applied unless specifically approved by the Inspector. The procedure
and the maximum acceptable temperature shall be as stated in paragraph 7.19 of CPOCGS-ST-0002.
7.7.7
The weld contour employing such a manner that the mean slope through the weld zone
does not exceed 1:4 shall be opted to ensure a smooth transition between the faces with the
offset of the thickness of abutting members exceeding maximum permitted offset,
measured on any of the two faces of assembly:
1) 3 mm when thinner member is not in excess of 12.7 mm (1/2”)
2) 4 mm when thinner member exceeds 12.7 mm (1/2”) up to 25.4 mm (1”)
3) 5 mm when thinner member exceeds 25.4 mm (1”)
Outside the above limits, the thicker member shall be tapered by machining or grinding to a
slope of not less than 1:4.
7.8
7.9
Weld Identification and Marking
7.8.1
Prior to fabrication, the Contractor shall establish an identification system for qualified
welders and welding operators and a comprehensive numbering system that provides
unique identification of each weld and the welder(s) or welding operator(s) who performed
the welding.
7.8.2
The numbering system shall be used for identification purposes at each weld, on all
shop drawings, and for indexing all NDT inspection reports and repairs. The identification
system shall be subject to review and approval by COMPANY. During fabrication, the
system shall be subject to audits.
7.8.3
Where the welders are being tested, they shall permanently mark with paint stick or low
stress metal stamp each weld with his identifying mark.
Tubular Splices
7.9.1
Splices shall be full penetration single-vee (‘V’) or double-vee butt joints welded from both
sides in accordance with the relevant welding procedure.
7.9.2
Butt welds in jacket legs, piles, and conductor pipes (made in the fabrication yard) shall be
backgouged and welded from both sides. Welding back-up rings shall not be used for butt
welded joints of structural tubular members. In joints where welding must be done from
only one side, the members shall be carefully contour-bevelled and fitted to achieve
complete weld penetration in accordance with the joint geometry and configuration set
forth in Figure 5.3 and Table 5.5 of AWS D1.1.
7.9.3
No two circumferential seams shall be located closer than one pipe diameter or 900
mm whichever is less.
7.9.4
There shall be not more than two girth welds in any three (3) metres interval of pipe.
7.9.5
Longitudinal seams shall be radially offset by a minimum 90 degrees wherever possible
and shall not less than 30 degrees without prior approval from COMPANY.
7.9.6
Longitudinal seams in adjacent cans shall be separated from circumferential weld at
least 250 mm.
7.9.7
Splices in piles shall have a minimum distance between girth welds of twice pipe diameters
or 2 metres whichever is less.
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Beam Splices
7.10.1 All splices shall be made with full penetration butt welds and shall be made to produce
members whose straightness equals that of uncut member.
7.10.2 Web of all plate girders shall be full penetration welded to flanges of plate girders unless
noted otherwise on the structural drawings.
7.10.3 Welded field splices should be arranged to minimise overhead welding.
7.10.4 Where strength welds are required by the drawings, or otherwise, to extend only partially
around a member or plate joint, a 1/8 in. (3 mm) fillet seal weld shall be deposited
continuously throughout the remaining distance around the member or plate.
7.10.5 COMPANY places special emphasis on the complete seal welding of all intersections
(where there is no strength welds) between steel members of special note are the beam-todeck plate and beam-to-beam intersections on the superstructure.
7.10.6 Splices for welded plate girders shall not be located to each other closer than twice the
girder depth or one metre whichever is smaller.
7.10.7 Splices for beams shall not be within L/8 from the supports or at the midspan (L/4), where
L is the beam span between two supports. Splices for cantilever beams shall be located
closer to free end rather than to support.
7.10.8 Splices between sections of beam (i.e. rolled or built-up sections) shall be made in a
single transverse plane (i.e. weld flanges and web in the same plane). The design of weld
grooves shall result in a continuous and full penetration weld over the complete crosssection.
7.11
Welded Connections
7.11.1 All butt welds shall be double sided welds, unless specifically approved by COMPANY on
Approved For Construction (AFC) drawings. In case of back pass, the root weld shall be
ground or gouged and ground to sound metal before welding on that side. This shall also be
mandatory for circular welds in tubulars with OD ≥ 26”.
7.11.2 Due consideration shall be paid to welds subject to cyclic/fatigue stresses during
service. Supporting structure for rotating machinery of power in excess of 100 kW
(unless otherwise agreed) or for vibration inducing machinery such as diesel
engines or reciprocating compressors irrespective of their power shall be considered
as fatigue sensitive structure with respect to weld design, performance and inspection.
Weld profiling by grinding may be deemed necessary.
7.12
Fillet and Seal Welds
7.12.1 All faying surfaces, including those between deck plate and its supporting structural
members, shall be seal welded against corrosion by continuous fillet welds with a
minimum of 1/8 in. (3mm) fillet seal weld in all areas where strength welds are not
required.
7.12.2 All fillet welds made with stick electrodes shall include two passes minimum on Special
and Primary Category members. Filled welds may be used only where shown on the design
drawings.
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7.12.3 Any surface inaccessible to coating but requiring coating shall be sealed by seal welds
or by “boxing in” with steel plate. All “boxing in” designed by Contractor shall require prior
approval from COMPANY.
7.12.4 All welds including fillet welds shall be continuous, unless otherwise specifically agreed
with the COMPANY. Minimum size of fillet welds shall be as per Table 7.1, always
providing that the minimum throat (a = 0.7 L) is met.
7.12.5 Seal welds shall be subject to Welding Procedure Qualification tests according to the
same requirements as those for fillet welds.
Table 7.1 - Minimum Size of Fillet Welds
Minimum
Thickness/Throat(mm)
Material Thickness
t (mm)
Minimum Leg Size of
Fillet Weld2) (mm)
t ≤ 12
51)
3.51)
12 < t ≤ 20
6
4.2
t > 20
8
5.7
Notes:
1) Minimum leg size shall be 6mm with minimum throat of 4.2mm for cyclically loaded
structure
2) This leg size applies provided that the stated minimum weld throat “a” is met (see
paragraph 7.12.4)
7.13
Stiffeners and Padeyes
7.13.1 Stiffeners shall be full penetration welded to top and bottom flanges and fillet welded to
webs unless otherwise noted on the Structural Drawings.
7.13.2 Stiffeners shall be accurately located and neatly fit between flanges of beams or girders
when full surface contact is required. The ends of stiffeners shall be milled or smoothly
ground to conform to the geometry of the member to which it is being attached or it shall
be bevelled in such a manner as to assure 100 percent fusion in the root of the attachment
weld, as dictated by the drawings.
7.13.3 Lack of fusion, incomplete penetration and undercut are not acceptable in welds of
padeyes or components subject to concentrated lifting loads (e.g. hooking parts of lifting
devices and accessories)
7.14
Preheating and Interpass Temperature
Preheating and interpass temperature shall comply with the recommendations defined in ANSI /
AWS D1.1 and the following requirements:
1) Preheating shall be carried out by electrical resistance or induction equipment or with gas
burners specifically made and shaped for this type of operation. Torches for flame cutting or
gouging shall not be used for preheating purposes.
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2) When the ambient temperature in the immediate vicinity of the weld is below + 5°C the weld
area shall be preheated to 20°C minimum and this temperature shall be maintained during
tacking and welding (refer also to paragraph 7.1.17).
3) Preheat and interpass temperatures must be sufficient to prevent cracking formation. Preheat
temperature above the specified minimum as stated in ANSI / AWS D1. 1 may be required for
highly restrained welds. In joints involving combination of base metals, preheat shall be as
specified for the higher strength steel and thickest material being welded. The interpass
temperature shall not exceed the maximum temperature allowed in any change outside -0°C, +
25°C from that of qualification test and is restricted to 250°C max.
4) The specified preheating temperature shall be reached throughout the plate wall thickness
over a distance equal to the thickness of the part being welded, but not less than 76 mm (3”) in
all directions from the weld.
5) Preheating when specified shall be applied before tack-welding and shall not exceed the
maximum allowed as point (3) above. If the interpass temperature falls below the required
preheat temperature at any time during production, then welding must be halted until the
correct preheat has been re-established.
6) The temperature measurement for preheating and interpass temperature may be by
thermocouples, temperature indicating crayons or contact pyrometers or a combination of these
methods as may be appropriate for the type of joint being heated and method of heating.
7.15
Weld Profile
7.15.1 All T-K-Y welds in fatigue sensitive areas will be noted on the design drawings. The weld
surface profile shall be prepared and tested in accordance with AWS D1.1, Paragraph
C2.20.6.6.
7.16
Arc Strikes
7.16.1 Arc strikes outside the weld groove area are not allowed. Arc strikes outside the weld
groove area shall be removed by grinding. All indications of cracking shall be subject to
grinding and re-inspection to insure complete removal.
7.16.2 Hard spots resulting from accidental stray arcing shall be removed by grinding. On High
Strength Steels (i.e. specified YS above 295 MPa), the ground areas shall then be
inspected by MPI or LPI.
7.17
Weld Interruption
7.17.1
Weld metal deposition may be interrupted (i.e. stopped for a period greater than that
necessary to de-slag, grind or change electrode/wire) only under one of the following
conditions:
1) For welds where electrical preheating is maintained, an indefinite interruption will be
permitted subsequent to completion of the root and first fill.
2) For welds where no preheating is required, or where preheating cannot be
maintained, an indefinite interruption will be permitted when the throat thickness of the
partially completed weld is at least 10mm or after deposit reaches 1/3 thickness of the
weld.. With the approval of COMPANY, this restriction may be waived for assemblies
where stresses can be shown to induce low ligament stresses. Before welding is
recommenced, the weld involved shall be fully inspected by MPI. This MPI may be
waived in the case of root passes where the welding procedure involves complete re-
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melting of the root pass by SAW or removal of the root pass by subsequent back
gouging.
3) Welding may be interrupted after deposit reaches 1/3 thickness of the weld or more
than 10mm throat thickness of weld. When welding is interrupted before deposit
reaches 1/3 of the weld thickness, preheating may be waived provided the welding
procedure has been so qualified.
4) If interruption of welding occurs after the preheated joint is half filled or more than 10
mm throat thickness of weld, the preheat may be removed provided that slow controlled
cooling of the weld area is insured.
5) Whatever the joint type (preheated or not), before continuation of welding, the weld is
to be inspected, visually for cracks and, if required by the Inspector, tested by Magnetic
Particle Testing.
6) For welds with throat thickness less than 10mm or showing defects after MPI, the weld
shall be completely removed, the preparation reinstated and re-welded.
7) No chipping or grinding of the weld reinforcement shall be permitted, except when
deemed necessary by the Inspector or indicated on approved drawings.
8) No welding shall be carried out on base material which has been cold formed to a
permanent deformation exceeding the values expressed as maximum acceptable
Percentage Strain (PS) of 5 % and 4 % for temperate/warm seas and cold seas,
respectively, unless stress relieving is planned or strain ageing tests have shown that
acceptable impact results are obtained on base material (see strain ageing test
procedure shall be as follows:).
The strain ageing test shall be made as follows on a steel sample:
a) Tensioning of the sample so as to obtain the same permanent elongation as that
anticipated for the final product
b) Then, artificial ageing by heat treatment at 250 °C for one hour.
9) Reference shall be made to paragraph 7.7 and 6.4.6 regarding wide gap procedures.
7.18
Post Weld Heat Treatment (PWHT)
7.18.1 Post Weld Heat treatment (PWHT), is required only when specified by contract documents,
identified on drawings, or required by welding procedure. PWHT when required, shall be in
accordance with AWS D1. 1 except as modified below:
1) When PWHT is required, the Contractor shall submit a PWHT procedure and obtain
approval from COMPANY prior to application of any PWHT.
The maximum temperature for API 2Y, API 2W, or any quenched and tempered or
thermo-mechanical control processed steel, shall not exceed 1100 °F (593 °C) or the
tempering temperature, whichever is less.
2) Thermocouples shall be attached directly to the weldment (near the weld) to be
PWHT and the full temperature cycle automatically recorded. The thermographs
produced shall be included in the final documentation package.
3) All final visual inspection and NDE shall be completed or repeated after PWHT.
Welding shall not be conducted on PWHT components without the approval by
COMPANY except for welds to connect items to the structure (i.e. stub to brace
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welds, core or barrel to leg welds, etc.). The PWHT of nodes, when required, shall be
performed on the node as a complete component if practical.
7.18.2 PWHT when required shall be carried out by local heating or furnace heating according to
ANSI / AWS D1.1 and the following requirements, unless recommended procedure and
temperatures furnished by manufacturer of the material are different.
1) PWHT shall be performed at soaking temperature not exceeding the values hereafter
for a time of two minutes per mm thickness up to 76.2mm (3”) and 2hrs 30 minutes plus
1 minute for each additional mm over 76.2 mm (3”):
a) 580°C ± 15°C for controlled rolled steels
b) 580°C ± 15°C or tempering temperature minus 30°C (the lowest
temperature) for quenched and tempered steels 600°C ± 15°C for normalized
steels and other C-steels
2) When local PWHT is carried out, the specified temperature shall be maintained over a
PWHT when required shall be carried out by local heating or furnace heating
according to region extending minimum three times the material thickness on either side
of the weld
3) When PWHT is carried out in a furnace, the furnace atmosphere shall be controlled so
as to avoid excessive oxidation of the surface of the fabrication. There shall be no direct
impingement of the flame on the fabrication.
7.18.3 Heat treatment records
The heat treatment cycle shall be recorded using thermocouples in effective contact with
the fabrication and equally spaced over the heated area, both inside and outside the
fabrication PWHT charts shall be properly marked and scales clearly identified. Charts
shall be submitted to the approval of the Inspector.
7.19
Temporary Welds
7.19.1 Temporary welds shall be minimized. When temporary welding is deemed necessary,
welding shall be carried out according to the same procedures that govern the permanent
structural part in question (i.e. same care, consumables, preheating, etc., as required for the
structural part).
7.19.2 Temporary welds (for temporary handling attachments, lugs, etc.) shall be minimised.
Temporary welds or fabrication aids shall not be made in high stress areas where tubular
members intersect. Temporary welding shall be performed with the same care, materials,
minimum preheat, procedures as for the permanent weld installations and by the qualified
welder. These welds shall not be made within 100 mm or 2 times the chord thickness of a
tubular joint, whichever is greater.
7.19.3 Preheat for temporary welds shall be a minimum of 50 °C higher than specified on the
applicable welding procedure.
7.19.4 All fabrication aids shall be removed unless approved by COMPANY. Removal shall be
accomplished by cutting no closer than 5 mm from the main member and the remainder
ground flush. It is permissible to grind up to 1.6 mm into the base metal surface to remove
any undercut associated with the attachment weld. If COMPANY observes damage to the
primary structure as a result of flame cutting or gouging, the damage shall be rectified by
grinding followed by repair welding. The cutting position shall then be changed to 8 mm
from the base metal surface.
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7.19.5 All areas of primary structural members from which temporary attachments are completely
removed shall be examined by magnetic particle. Gouges deeper than allowed by the
material specification thickness tolerance shall be reported to COMPANY/Contractor and
repaired.
7.19.6 The temporary welds shall subsequently be removed and ground flush with the base
material. On High and Extra High Strength Steels (i.e. specified YS above 295 MPa) the
grindings shall then be inspected by MPI or LPI.
7.20
Cleaning
Upon completion of each welding pass, the weld shall be cleaned of spatters, slag and flux deposits.
When the welded joint is completed, the adjoining welded surfaces shall be thoroughly cleaned of
all spatters and deposits.
8.0
INSPECTION AND TESTING
8.1
General
8.1.1
The Contractor shall inspect all work during fabrication. The mandatory inspections
specified herein shall be made at the Contractor’s expense using his personnel, equipment,
and facilities. Sufficient inspection shall be made by the Contractor to ensure that the
materials, fabrication, and testing comply in all respects with the requirements of this
specification. COMPANY will conduct audits during fabrication.
8.1.2
The Contractor shall have and make readily available to involved personnel copies of
the latest edition of the applicable specifications and codes at all fabrication sites.
8.1.3
The Contractor shall furnish, install, and maintain in a safe operating condition any
scaffolding, ladders, walkways, and lighting necessary for safe inspection.
8.1.4
Welds shall not be coated before they have been inspected and accepted.
8.1.5
Welds shall be non-destructively examined no sooner than 48 hours after welding.
8.1.6
If difficulty is experienced in evaluating defects revealed by radiography, ultrasonic testing
shall be used to facilitate interpretation, or vice versa.
8.1.7
Inspection and non-destructively examined no sooner than 48 hours after welding.
8.1.8
The COMPANY shall have the right to require inspection of any weld (not previously
accepted) by either non-destructive or destructive methods to verify the structural integrity of
any welded portion of the structure. This optional inspection can be for the purpose of
routine quality control or to further investigate apparent defects detected visually.
Defective welds found during a COMPANY optional inspection shall be repaired and the
cost of removal, repairs, and re-inspection shall be at the Contractor’s expense. Welds
found to be satisfactory shall be repaired and the cost of removal and repairs be at the
COMPANY’s expense. COMPANY shall not be held liable by the Contractor for loss of
time during these tests.
8.1.9
Contractor will provide full facilities for ultrasonic and radiographic inspection of welds.
Facilities shall include equipment for film development and full time services of personnel
currently certified to Level II in accordance with ASNT TC-1A or with equivalent
qualifications approved by the COMPANY.
8.1.10 Prior to the inspection of the work, the Contractor shall clean the working area sufficiently
to allow proper access to the work. The Contractor shall furnish, install, and maintain in a
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safe operating condition, the necessary scaffolding, ladders, walkways, lighting, etc., to
allow for safe and thorough inspection.
8.1.11 Weld inspection extent will be in accordance with Appendices A and B and the following
criteria.
8.1.12
Welding shall be visually inspected. Visual inspection shall be made during fit-up, while
the operators are making the welds, and again after the work is completed. After the
welding is completed and the welds thoroughly cleaned, the welds shall be inspected with
magnifiers under strong, adequate light for surface cracking, porosity, entrapped slag,
excessive roughness, unfilled craters, gas pockets, undercuts, overlaps, insufficient weld
size, and excessive concavity or convexity.
8.1.13 The Contractor shall adequately clean all welds of slag, spatter, dirt, grease, oil, and
loose scale to aid in the visual inspection of those welds. If ultrasonic testing is required,
the welds shall be brush blasted. The surface condition for properly applied welds should be
adequate for proper interpretation of test results; therefore, any additional preparation of
surfaces necessary, prior to instituting specific non-destructive mediums, will be provided
by the Contractor at his expense.
8.1.14 All welds vital to the strength and integrity of the structure are defined as “critical welds”
and shall be subject to further examination by means other than visual. Welds designated as
critical shall include but not necessarily be limited to:
1) Splices in primary structural members
2) Joints in primary structure (tubular and otherwise)
3) Welds on padeyes
4) All welds on crane pedestals
8.1.15 Critical welds shall be radio-graphically inspected throughout their full length, where
possible. Those critical welds that cannot be radio-graphically inspected shall be tested by
ultrasonic methods.
8.1.16 Inspection records shall be submitted to the COMPANY for review and as a final record
of all welding performed on the project. The COMPANY retains the final right to determine
the acceptability of any weld. Interpretation of test results will be in accordance with the
guidelines set forth in AWS D1. 1 or API RP 2X as applicable.
8.1.17 The COMPANY shall have the right to examine the work at any time.
8.1.18 It shall be clearly understood that weld acceptance shall not relieve the Contractor of the
responsibility for satisfactory construction of all work in accordance with the contract
requirements.
8.1.19 All welds will be visually inspected in accordance with section 6.9 of AWS D1. 1. The
standard of acceptability for visual inspection shall be as per Table 6.1 of AWS D1. 1, as
applicable. Weld areas containing defects exceeding these standards of acceptance for
visual inspection, shall be repaired. Undercut shall be limited to a maximum of 0.01 in.
(0.3 mm).
8.1.20 The COMPANY is vitally concerned with weld quality, geometry, fit -up, and size.
Consequently, COMPANY will impose the use of gauges and non-destructive test
procedures when and where it is deemed necessary.
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8.3
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Qualification of NDT Procedures and Personnel
8.2.1
All inspectors shall be AWS QC 1 certified (or acceptable equivalent) for visual inspection,
except specialty technicians (PT, MT, UT, and RT) who shall be qualified and certified
according to the guidelines ASNT SNT-TC-1A or equivalent. Additionally, all specialty
technicians may be required to demonstrate their capabilities with a practical site test for
COMPANY approval.
8.2.2
The required NDE methods and the minimum extent of inspection shall comply with API
RP 2A Table 13.4.3 and the additional requirements in Attachment 1 and 2 of this
specification.
8.2.3
The Contractor shall submit NDT procedures for COMPANY approval prior to
commencement of work.
Radiographic Examination
8.3.1
Radiographic procedures and Standards shall be in accordance with Section 6, Part E
of AWS D1. 1. The standard of acceptability for welds shall be as per Section 6.12 of AWS
D1. 1. Radiographic examination shall be performed but not limited to the weld areas as
follows:
1) The intersection of all tubular member girth and longitudinal seams.
2) Subsequent to trimming, the extreme ends of each longitudinal seam of fabricated
tubulars to be employed as piling or for construction of jackets and other truss
structures shall be examined by radiography. In addition, one radiographic film not less
than 15” (380 mm) in length shall be obtained for each ten feet of weld length or fraction
thereof in each individual tubular length. Location of this spot exposure shall be at the
discretion of the COMPANY representative. When spot testing reveals indications of
rejectable discontinuities that require repair, the extent of those discontinuities shall be
explored. Two additional spots in the same segment of weld joint shall be taken at
locations away from the original spot. The location of the additional spots shall be
agreed upon between the Contractor and COMPANY Representatives.
3) When either of the two additional spots show defects that require repair, the entire
segment of weld represented by the original spot shall be completely tested. If the weld
involves more than one segment, two additional spots in each segment shall be tested at
locations agreed upon by the Contractor and COMPANY representative, subject to the
foregoing interpretation.
4) All circumferential welds of piling and all tubulars for truss structure fabrication shall be
100 % radiographically inspected. When the girth seam is intersected by a longitudinal
seam of a fabricated tubular, the end inspection required above may be simultaneously
performed during examination of the circumferential weld.
5) Any questionable weld defect.
6) One-hundred percent (100 %) of all beam splices in skid beams, main truss beams,
and other major beams.
Twenty percent (20 %) of all full section splices in minor or secondary beams.
8.3.2
Weld areas containing defects exceeding the acceptance standards in AWS D1. 1,
Section 6.12, as revealed by radiographic testing, shall be repaired. If 20 percent or more
1
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the radiographs of welds made by a given welder contain defects requiring repair, 100 percent
radiographic inspection of that welder’s work will be required at the Contractor’s expense.
8.4
Ultrasonic Examination
8.4.1
The ultrasonic examination procedures shall be established by an ASNT Level III
ultrasonic specialist. The procedure shall define equipment, techniques, and methods
consistent with the design requirements. As a minimum the essential variables listed in API
RP 2X shall be detailed in the written procedure and submitted for COMPANY approval
prior to use during trial and subsequent examination. Variations from the proven procedure
shall be cause for re-qualification.
8.4.2
Ultrasonic examination of groove welds in structural shapes and plates shall comply with
API RP 2X / AWS D1.1 Section 6, Part F. Acceptance criteria shall be per AWS D1.1
Section 6.13.
8.4.2
Ultrasonic examination of tubular structural welds shall comply with API RP 2X. T-, Y-, or Kconnections shall comply with level “C” acceptance weld quality. Unless otherwise
approved by COMPANY representative, level “A” acceptance weld quality shall apply
where UT is substituted for radiography.
8.4.4
UT shall be carried out in accordance with AWS D1 .1 / Class R for all kinds of joints. For
T, K, Y joints and tubular joints with full penetration welds (refer to paragraph 7.8 of
CPOC-GS-ST-0002), the “back up weld” at the root shall also be part of the testing. However,
this back up weld shall be evaluated as per AWS D1.1 / ClassX.
8.4.5
UT can be used in lieu of RT when nominal Wall Thickness greater than 20 mm for
Special steel category, 15 mm for Primary Steel category and 12.7 mm for Secondary Steel
category.
8.4.6
For K or 1/2 V bevels, tandem technique is mandatory for special category (procedure to
be submitted to COMPANY for approval).
8.4.7
Plate or pipe to be used as lifting aids, node cans in chord members, flanges or critical
or girders requiring substantial stiffening, and all applications where the member is subject to
substantial Z-direction loading shall be ultrasonically examined. Examination and reporting
requirements of ASTM A578 shall apply.
8.4.8
The intersection location (footprint), including a six inch wide band shall be examined in
accordance with ASTM A578 acceptance standard level II.
Members with flaws that would interfere with weld inspection may be positioned so that
acceptable material is located under all brace footprint areas. Weld repairs of members with
unacceptable flaws may only be made with prior COMPANY approval using a
COMPANY approved weld repair procedure.
8.4.9
Ultrasonic inspection of tubular joints shall be performed in accordance with API RP 2X,
“Ultrasonic Examination of Offshore Structural Fabrication”. Level A rejection criteria shall
be enforced.
Ultrasonic examination shall be performed but not limited to the weld areas as follows
1) Regardless of previous plate examinations and prior to framing any member to
another, such that loading is directed perpendicular to the surface of the mating
member, the area of framing shall be examined for the presence of non-metallic
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inclusions accepted by prior examinations and/or laminations and tears resulting from
forming operations.
2) The area of framing shall be inspected 100 % by ultrasonic techniques along the
plane of fusion and for a distance equal to twice the branch member thickness on
either side of the plane of fusion. Freedom from all defects in the area is desirable and no
single imperfection which cannot be contained within a one inch diameter circle shall
be permitted in this area. To the maximum extent possible, all areas of imperfection
shall be rotated to place all defects outside the areas to be welded.
3) All chord-to-web member connections in tubular trusses (jackets, bridges, etc.) shall be
inspected 100 % by ultrasonic techniques.
4) Padeyes and temporary supports with full penetration joints shall be inspected 100 % by
ultrasonic techniques.
8.4.10 Ultrasonic inspection of joints in beams shall be performed in accordance with AWS D1.1,
Section 6,Part F. The standard for acceptability shall be as per Section 6.13 of AWS D1.1.
8.4.11 Weld areas containing defects revealed by ultrasonic inspection, exceeding the
acceptance standards in AWS D1.1, Section 6 or API RP 2X, as applicable, shall be
repaired.
8.4.12 The UT equipment shall have been calibrated since less than six months by an
independent laboratory. The calibration certificate shall be made available to the Inspector.
8.5
8.6
Magnetic Particle Inspection (MPI)
8.5.1
Procedure to be as per ASTM E709 or Article 7 of ASME V.
8.5.2
MPI can be substituted by LPI upon prior approval of Inspector.
8.5.3
Acceptance criteria for MPI shall be as per Table 8.1 of this specification below.
Liquid Penetrant Inspection (LPI)
8.6.1
Procedure to be as per ASTM E165 or Article 6 of ASME V.
8.6.2
Acceptance criteria shall be as per Table 8.1 of this specification
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Table 8.1a - Standards of Acceptance for Weld Defects in Structural Steels for
Internal Defects by RT
Steel Member Category
Type of defects
Special Steel
Primary Steel
Secondary Steel
Not acceptable
Not acceptable
Not acceptable
Lack of fusion or Incomplete
penetration
Length ≤ t/3
Max. 12 mm
Length ≤ 2t/3
Max. 25 mm
Length ≤ 3t/2
Max. 50 mm
Slag inclusion
Length ≤ 2t/3
Max. 50 mm
Width ≤ t/6 Max.
4 mm
Length ≤ 3t/2
Length ≤ 3t Max.
Max. 75 mm
100 mm Width ≤
Width ≤ t/4 Max. t/3 Max. 6 mm
5 mm
Cracks
Porosities
 Isolated: max. pore
diameter
t/5; max. 3.5 mm t/4; max. 3.5 mm
t/3; max. 4.0 mm
 Cluster: max. pore
diameter
2 mm
2 mm
2 mm
 Scattered: max. accumulated
Pore diameters in any 10 x
50 mm
10 mm
15 mm
20 mm
Area of weld
Table 8.1b - Standards of Acceptance for Weld Defects in Structural Steels for
Surface Defects by Visual Inspection or MPI
Steel Member Category
Type of defects
Special Steel
Primary Steel
Secondary Steel
Cracks
Not acceptable
Not acceptable
Not acceptable
Undercuts
- Static loads =
Depth ≤ 0.4 mm
Length ≤ 25 mm
- Static loads =
Depth ≤ 0.8 mm
Length ≤ 25 mm
- Static loads =
Depth ≤ 0.8 mm
Length ≤ 50 mm
- Cyclic loads =
Not acceptable
- Cyclic loads =
Not acceptable
-
Lack of fusion or Incomplete
penetration
Not acceptable
Not acceptable
Length ≤ t/2
Max. 10 mm
Porosities
Not acceptable
Size ≤ t/4
Size ≤ t/3
Max. 3.5mm
Max. 4.0mm
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Table 8.1c - Standards of Acceptance for Weld Defects in Structural Steels for
Surface Defects by LPI
Steel Member Category
Type of defects
Special Steel
Primary Steel
Secondary Steel
Cracks
Not acceptable
Not acceptable
Not acceptable
Linear Indication7) 8)
- Static loads =
- Static loads =
L ≤ 12mm
where L = length of indication
L ≤ 2 mm
- Cyclic loads =
Not acceptable
L ≤ 4 mm
- Cyclic loads =
Not acceptable
-
D < 4mm
D < 6mm
D < 8mm
Non-linear indication8)
8.7
Where D = major axis
dimension
Production Tests
8.7.1 General
1) Welding shall be carried out in accordance with requirements of CPOC-GS-ST-0005.
2) For fabricated pipes, as per API 2B requirements, 100 % UT and 10 % RT on the ends
shall be carried out
8.7.2 Production Tests
Production tests shall be carried out on finished tubulars pertaining to Special and Primary
Steel Category members. Production tests shall include tests on base metal and tests on
welds as indicated below:
8.7.3 Production Tests on Base Metal
The production tests on base metal shall be as per paragraph 6.4.10.5 of CPOC-GS-ST-0002.
8.7.4 Production Tests on Welds
1) Production test plates shall be welded as longitudinal extension pieces attached to the
seams during production welding. Where the Inspector deems necessary, the
Contractor shall prepare representative circumferential weld test pieces. These are not
normally required where the circumferential seams are welded to an identical weld
procedure as the longitudinal seams.
Each production test plate shall be labelled with a machine reference number and for
longitudinal seams a tubular reference number. Test pieces for circumferential seams
must be welded on identical machines and to identical procedures as the seams they
represent
2) Weld production tests shall be carried out per each WPS regularly once in every
twelve (12) circumferential and once in every twelve (12) longitudinal seams in Special
category tubulars and once in every fifty (50) circumferential and fifty (50) longitudinal
seams for Primary Category tubulars. The production test programme shall be made so
as to test equally, as far as possible, all the wall thicknesses covered by the said WPS.
3) All tests specified for the welding procedure qualification test (see paragraph
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Welding procedure qualification for plates and tubulars (except for tubular nodes) shall be
carried out. However, the impact test and tensile test are modified as follows:
a) The transverse tensile test consists of only one specimen
b) The impact test consists of only two sets of specimens: one with the notch centered
in the weld axis and the other one with the notch located on the Fusion Line (FL) or
Heat Affected Zone (HAZ) and centered at the place where the lowest average
absorbed energy has been measured during the Welding Procedure Qualification
Test (i.e. on FL or 2 mm from FL or 5 mm from FL). This test location shall be agreed
with the Inspector.
c) Production test pieces shall be 100 % non-destructively examined and
mechanically tested in full compliance with paragraph ‘Testing procedures and
standards of acceptance) of this specification.
4)
Failure: production test welds which fail the requirements of paragraph 8.3 through
8.6 of this specification shall be rejected and brought to the attention of the Inspector
and the cause of the failure shall be established by the Contractor. Further
examination of welds made using the same welding procedure or by the same welder
shall be carried out to ensure that unacceptable welding is not present in the structure.
8.7.5 Weld inspection
In addition to the 100 % visual inspection, radiographic and ultrasonic testing shall be
carried out according to Section 8 of this specification to the following extent on each
finished tubular or section of tubular:
1) Longitudinal weld: 100 % inspection by NDT (10 % NDT inspection for Secondary steel
category tubulars), plus radiographic inspection of weld extremities over 200 mm
minimum.
2) Girth weld: 100 % inspection by NDT, whatever the tubular category.
NDT means radiography for WT ≤ 15 mm and Ultrasonics (UT) for WT > 15 mm. When
capping or back pass is made with a process other than SAW, then MPI shall also be
required to 100 % extent on Special and Primary steel category members.
3) The NDT requirement for circumferential seam welds in jacket legs with the material properties
of specified YS greater than 295 Mpa (42 ksi), CE greater than 0.41 % and wall thickness
greater than 25.4mm, can be 90 % RT plus 10 % UT instead of 100 % RT as in Attachment
2.
9.0
WELDING REPAIRS
9.1
General
9.1.1
The Contractor shall repair or replace all welds that do not meet the requirements of
the appropriate Codes and Standards and this specification.
9.1.2
Repairs to weldments and parent material shall be in accordance with ANSI / AWS D1.1,
and this specification.
9.1.3
Repair welding procedures specifications shall include the method for removal of defects,
preparation of weld area and subsequent non-destructive testing in addition to the details
outlined in welding procedure specification. Repair welding procedure specifications shall
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Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
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Page
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be submitted to COMPANY for review and APPROVAL prior to the commencement of
repair.
9.1.4
It shall not be construed as unreasonable for the COMPANY to request proper repair of
any defects in welds or materials that they consider to be detrimental to the strength and
usefulness of the structure.
9.1.5
Repaired defects shall be inspected by the same criteria used for the original inspection.
9.1.6
The repair of all defects shall conform to the following requirements and conformance
shall be subject to COMPANY approval.
1) Laminations extending into the face or bevel of a pipe are considered injurious
defects. Pipe containing such injurious defects shall be cut back until all laminations are
removed.
2) For all members other than API 2H material, defects in the finished tube not deeper
than five percent of the specified nominal wall thickness, and mechanical marks not
deeper than five percent or 1/16 in. (1.6 mm) whichever is less need not be removed.
However, extent of defects must be determined. Shallow imperfections shall be
ground to sound metal. The ground area shall be well joined and the thickness of the
ground plates shall not be reduced more than seven percent of the nominal thickness,
but in no case more than 1/8 in. (3 mm). If the depth of the defect exceeds the above
limits, but is not more than 20 percent of the nominal thickness, welding repairs may be
performed with COMPANY Representative’s approval, or the section rejected.
3) Repair of defects deeper than 20 percent of the nominal wall thickness, or repair of
defects with length and/or width more than 20 percent of nominal diameter is not
acceptable. For tubulars made from thermally treated plate, repair by welding shall be
permitted only with the specific written COMPANY approval.
4) Contractor shall be allowed only TWO opportunities to repair a defect. Recurrence of the
defect shall be cause for rejection at the discretion of COMPANY.
The Inspector may request the use of extra low hydrogen electrodes for highly restrained
weld repairs.
9.1.7
Notification
1) COMPANY shall be notified before repairs are made on defective welds and base
material
2) The COMPANY shall be notified before repairs are made on defective material and welds.
Repairs made without reasonable notice shall be subject to any form of testing (both
destructive and non-destructive) to assure adequate repair and all removal, repair,
and retesting deemed necessary by the COMPANY shall be at the Contractor’s
expense.
3) Welds that are subjected to magnetic particle testing (MT) and Liquid Penetrant testing
(LT), shall be performed in accordance with Section 6.10 of AWS D1.1. Magnetic
particle inspection shall be by the AC yoke method using a white background and
black ink.
4)
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OFFSHORE STRUCTURAL WELDING AND
INSPECTION
CPOC
9.2
9.3
Doc. No.
CPOC-GS-ST-0005
Rev.
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Date
31/03/2019
Page
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Method of Repair
9.2.1
Defects may be rectified by grinding, machining or welding. Peening shall not be
permitted.
9.2.2
Repairs at a same location shall be limited to 2 maximum or subject to acceptability of
number of repair cycle by supporting PQR.
9.2.3
Injurious defects shall be removed by grinding or machining and, when necessary,
repaired by welding carried out by qualified welders and using a previously qualified
Welding Procedure (see paragraph. 6.3). Preheating at an approved temperature shall be
carried out for steels with YS greater than 262 Mpa (38,000 psi) or WT greater than 25.4
mm (1”).
9.2.4
Repair of welds containing cracks shall be permitted only after the cause of cracking has
been fully clarified by Contractor to the satisfaction of COMPANY and the approval to
proceed is obtained from COMPANY.
9.2.5
Unacceptable defects shall be removed by grinding, machining or arc-air gouging. Where
arc-air gouging is used, all carbon, copper and other debris, including carburized metal,
shall be removed by grinding or other mechanical methods approved by the Inspector.
9.2.6
For partial repairs in welds, the cut out portion shall be sufficiently deep and long to
remove the defect. At the ends and sides of the cut there shall be a gradual taper from the
base of the cut to the surface of the weld metal. The width and profile of the cut shall
provide adequate access for re-welding. As a guide, the minimum repair length will not be
less than 100 mm (4”) even if the defect is of less extent, with 70 mm (2.75”) minimum at
the bottom of the repair groove.
9.2.7
The repair grooves shall be examined by LPI or MPI in the presence of the Inspector to
ensure that all defects are removed, prior to rewelding.
9.2.8
The external surface of the repair weld shall be subject to suitable shaping by grinding in
order to obtain a uniform appearance and to merge smoothly into the original weld metal
and/or into the adjacent base metal.
Approval
9.3.1
After the initial joint is completed, only one (1) repair is allowed unless Approved by
COMPANY. At the discretion of COMPANY repeated repairs may mean the complete
removal of the entire weld metal back to its original joint preparation. Contractor shall
evaluate and determine the cause for recurrence of repairs of a similar nature and act
accordingly.
9.3.2
Each weld repaired area shall be 100 % re-inspected non-destructively according to
Section 8 of this specification. Additional non-destructive testing such as MPI and LPI may
be requested by the Inspector.
9.3.3
Repaired welds shall have 100 % NDT after repair.
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CPOC
10.0
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
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Date
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Page
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DOCUMENTATION
The documentation for each procedure shall contain, but is not limited to:
1)
Welding process(es) and type(s) (automatic, manual, machine, or semi auto), code
specification
2)
Joint design including arrangement of parts to be welded, weld layers and bead sequence,
backing, if used, and type of backing material.
3)
Base metals specification and type or grade, thickness, diameter, chemical analysis and
mechanical properties
4)
Filler metals specification and electrode size
5)
Weld position and progression
6)
Minimum preheat and maximum interpass temperature and means of maintenance
7)
Post weld heat temperature and time range
8)
Type and composition of shielding gases
9)
Electrical characteristics of current, polarity, amperage and voltage range, tungsten electrode
size and type, mode of metal transfer if GMAW, electrode wire feed speed.
10) Technique of joint cleaning, bead type, number of passes and electrodes
11)
Weld repair procedures including welder and foreman identification, type of filler meal, joint
preparation, preheat, root and final pass, nondestructive examination results.
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
CPOC
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
31/03/2019
Page
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LIST OF FIGURES.
1) VICKERS HARDNESS TEST LOCATIONS
2) CHARPY V-NOTCH TEST LOCATIONS
Figure 1a - Vickers Hardness Test Location for Welds
Notes:
1) Test load should be 5 kg or less
2) Specimen shall be polished well enough to clearly show the fusion line.
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CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
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Date
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Page
53 of 64
3) Indentations to be located as shown on the figures and as detailed below:
a) HAZ: Starting at 0.20 – 0.50 mm from the fusion line with three (3) indents at 0.50
– 0.75 mm intervals.
b) Weld Metal: A minimum of three equally spaced indents for each hardness
traverse.
5) Hardness traverse on fillet welds should be as detailed for T – connections Above
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
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Date
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Figure 1b - Vickers Hardness Test Location for Repair Welds
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
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Date
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1
Figure 2a - Charpy V - Notch Test Locations
Notes:
1) For base material thicknesses less than 19 mm (3/4 in.), only root location tests are required.
2) For base material thickness equal or more than 19 mm (3/4 in.) to < 50 mm, root and cap location
tests are required.
3) For base material thickness equal to or greater than 50 mm, two intermediate sets shall be cut in
addition to root and cap location tests.
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CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
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a) Partial – thickness repair
b) Through – thickness repair
1
Notch Specimen Location:
a) Notch at centerline of repair weld
b) Center of notch location on fusion line
1
c) Center of notch located 2mm from fusion line
d) Center of notch located 5mm from fusion line
Figure 2b - Charpy V-notch Test Locations in Weld Repairs
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
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Page
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Weld Procedure Qualification Tests Sampling of Test Specimens
Figure 3 – Butt Welds of Plates in Positions 1G, 2G, 3G, and 4G
Figure 4 – Butt Welds of Tubes in Positions 2G, 5G or 6G
(in 2G Position Only One Macro./Hardness Specimen is required)
Figure 5 – Full Penetration Groove Welds on Plates (T – Joint or Y – Joint)
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
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Page
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ATTACHMENT 1
PROCEDURE, STANDARDS AND ACCEPTANCE CRITERIA FOR STRUCTURAL
WELDING
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
CPOC
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
31/03/2019
Page
59 of 64
PROCEDURE, STANDARDS AND ACCEPTANCE CRITERIA
FOR STRUCTURAL WELDING
Testing
Procedure
Visual Inspection
To comply with the Drawing and the requirement of Section 6.9 of AWS
D1.1
Radiographic Test
AWS D1. 1 Section 6, Part E / Section 9, Part F
Ultrasonic Test
1 Test method in accordance with ASTM E164
2 Procedure and standards in accordance with AWS D1. 1, Section 6, Part F
Magnetic Particle Test
/ Section 9, Part F, and API RP 2X
Test method in accordance with ASTM E709
Liquid Penetrant Test
Test method in accordance with ASTM E165
Acceptance Criteria
Testing
Non – Tubular Member
Tubular Member
Visual Inspection
AWS D1.1 Section 6.9
AWS D1.1 Section 9.25
Radiographic Test
AWS D1.1 Section 6.12
AWS D1.1 Section 6.12
Ultrasonic Test
AWS D1.1 Section 6.13
AWS D1.1 Section 9.27.1 and API
RP 2X
AWS D1.1 Section 6.10
AWS D1.1 Section 6.10
AWS D1.1 Section 6.10
AWS D1.1 Section 6.10
Magnetic Particle Test
Liquid Penetrant Test
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
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ATTACHMENT 2
NDT EXTENT FOR WELDING OF OFFSHORE STRUCTURES
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
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PERCENTAGE OF WELDS FOR NON-DESTRUCTIVE TESTING FOR WELDING OF OFFSHORE
STRUCTURE
RT
UT
MPI
VI

= Radiographic Testing
= Ultrasonic Testing
= Magnetic Particle Inspection or Liquid Penetrant Test at COMPANY’s discretion
= Visual Inspection
JACKET
JACKET LEG
Circumferential Seam
NDT
RT
UT
% Length
100
100
% Joint
100
100

Heavy Wall Joint cans fabricated by Contractor.
Longitudinal Seam
RT
UT
12
90
100
100

Heavy Wall Joint cans fabricated by others.
Longitudinal Seam
UT
100
100

Tubular cans fabricated by contractor.
Longitudinal Seam
RT
UT
12
100
100
100

Grouting and flooring Connections
MPI
100
100

Tubular Joint cans fabricated by others and conforming to API2B,
per Mill Certificate:
Longitudinal Seam
VI
100
100
Grout packer wiper to leg
UT
100
100

BRACES, MAIN PILES & CONDUCTOR PILES

Circumferential Seam in Braces
RT
UT
100
100
100
100

Pile to Add-on Circumferential Joint (welded offshore while Pile
Driving
UT
100
100

Tubular Joint cans fabricated by contractor.
Longitudinal Seam
RT
UT
12
100
100
100

Tubular Joint cans fabricated by others and conforming to API2B,
per Mill Certificate:
Longitudinal Seam
VI
100
100
CPOC
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
Doc. No.
CPOC-GS-ST-0005
Rev.
1
Date
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Page
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
Tubular TKY Joints in Main Structure
NDT
UT
MPI
% Length
100
100
% Joint
100
100

Tubular TKY Joints in Conductor Framing
Caisson Framing
UT
MPI
100
100
20
20

Doubler Plate or Tubulars to Caissons or Anode
MPI
100
10

Doubler Plate to Leg or Brace
MPI
100
100
PADEYE
UT
MPI
100
100
100
100
BOATLANDING

Circumferential Seam
RT
100
50

Main Support TKY Joint
UT
MPI
100
100
100
100

Other TKY Joint
UT
MPI
100
100
10
50

Doubler Plate to Leg
MPI
100
100
BARGE BUMPER

Circumferential Seam
RT
100
100

Stab-in Points
MPI
100
100

Bumper to Doubler
MPI
100
100

Doubler Plate to Leg
MPI
100
100
RISER PROTECTOR


Circumferential Seam
TKY Joint
RT
UT
MPI
100
100
100
50
10
50

Doubler Plate to Leg
MPI
100
100
MPI
100
100
RISER CLAMPS

Stand-off to clamp Joints
CPOC
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
OFFSHORE STRUCTURAL WELDING AND
INSPECTION
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PUMP CASING, PULL TUBE CAISSON
NDT
% Length
% Joint
Longitudinal Seam
Circumferential Seam
RT
MPI
12
100
100
100
RT
UT
100
100
100
100
RT
UT
12
100
100
100
VI
100
100
DECKS
DECKS LEGS & COLUMNS

Circumferential Seam

Tubular Joint cans fabricated by contractor.
Longitudinal Seam

Tubular Joint cans fabricated by others and conforming to API2B,
per Mill Certificate:
Longitudinal Seam
PLATE GIRDERS/FABRICATED BEAMS

Butt and Splices
(if cannot RT)
RT
UT
100
100
100
100

Web to Flange (Fillet)
MPI
100
100

Web to Flange (Full Pen)
UT
100
100
TKY JOINTS

Girder to Column
UT
MPI
100
100
100
100

Brace to Column
UT
MPI
100
100
100
100

Brace to Girder
UT
MPI
100
100
100
100

Brace to Main Beam
UT
MPI
100
100
100
100
RT
100
100
BRACES

Circumferential Seam
CPOC

OFFSHORE STRUCTURAL WELDING AND
INSPECTION

CPOC-GS-ST-0005
Rev.
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Date
31/03/2019
Page
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NDT
% Length
% Joint
RT
UT
20
100
100
100
Tubular Joint cans fabricated by others and conforming to API2B,
per Mill Certificate:
Longitudinal Seam
VI
100
100
MAIN BEAMS, DECK BEAMS
Splices
(if cannot RT)
RT
UT
100
100
100
100
UT
MPI
100
100
100
100
RT
100
100
UT
MPI
100
100
100
100
Tubular Joint cans fabricated by contractor.
Longitudinal Seam

Doc. No.
PADEYES

CRANE PEDESTAL
Circumferential Seam

Beams to Pedestal

ANCILLARY SUPPORT FRAMING
Crane Boom, Life Boat Support, etc
MPI
100
100

Machinery Support and all other beam connections
UT
100
10
BRIDGES AND FLARE BOOMS

TKY Joints
MPI
100
100

Circumferential Seams
RT
100
100
Notes
1)
2)
3)
4)
All welds to be 100 percent Visual Inspected.
All Special and Primary steel fabrication welds to be 100 percent MPI or DPI.
All full penetration welds to be 100 percent Ultrasonic Tested.
Where percentages indicated above are less than 100 percent,
a) Location to be chosen by COMPANY Representative.
b) If defect discovered; equal, additional by UT or limited RT after the second test, full RT is required on that
member.
5) On locations where Ultrasonic Testing or magnetic Particle Inspection indicated above is not possible, Liquid Dye
Penetrant inspection may be substituted with COMPANY approval.
1