2885.2-2007 fixed

AS 2885.2—2007

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AS 2885.2—2007

Australian Standard® Pipelines—Gas and liquid petroleum

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Part 2: Welding

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This Australian Standard® was prepared by Committee ME-038, Petroleum Pipelines. It was approved on behalf of the Council of Standards Australia on 27 November 2006. This Standard was published on 27 March 2007.

The following are represented on Committee ME-038: • • • • • • • • • • • • • • • •

Australian Corrosion Association Australian Gas Association Australian Institute of Petroleum Australian Petroleum Production and Exploration Association Australian Pipeline Industry Association Bureau of Steel Manufacturers of Australia Cooperative Research Centre for Welded Structures Department of Labour New Zealand Check Department of Minerals and Energy WA Department of Mines and Energy (Qld.) Department of Mines and Energy (N.T.) Department of Natural Resources and Environment (Vic.) Gas Association of New Zealand Ministry of Energy and Utilities N.S.W. Primary Industries and Resources S.A. Welding Technology Institute of Australia (WTIA)

This Standard was issued in draft form for comment as DR 05463. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through public comment period.

Keeping Standards upup-toto- date

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Australian Standards® are living documents that reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting www.standards.org.au Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at [email protected], [email protected] or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

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AS 2885.2—2007

Australian Standard® Pipelines—Gas and liquid petroleum Part 2: Welding

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Originated as AS CB28—1992. Previous edition AS 2885.2—2002. Third edition 2007.

COPYRIGHT © Standards Australia All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher. Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia ISBN 0 7337 8141 1

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PREFACE This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee ME-038, Petroleum Pipelines, to supersede AS 2885.2—2002. The objective of this Standard is to provide requirements for the welding of pipeline designed and constructed in accordance with AS 2885.1.

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The objective of this revision is to include editorial changes, and technical changes, which became necessary as a result of experience in the use of the Standard in the four years since the previous edition was issued. The most important changes that have been made are the following: (a)

Material has been included defining the information that needs to be submitted in order that other welding processes that may be submitted for inclusion in the Standard may be considered.

(b)

Changes have been made to the application clause to clarify where the Standard is intended to be applied.

(c)

The methods and the requirements for qualifying welding procedures have been clarified.

(d)

A requirement for fracture toughness testing has been reintroduced for welds made to the requirements of Tier 1 where the welds are not made entirely with E4110 electrodes. (This requirement was inadvertently omitted from the 2002 edition.)

(e)

Important changes, corrections, and clarifications have been made to the essential variables.

(f)

The notched tensile test used in the previous Standard to determine whether overmatching is achieved has been deleted pending the performance of further research.

(g)

The acceptance criteria for the macro test have been clarified.

(h)

Changes have been made to the permissible limit and method of qualifying the limit of high-low.

(i)

Changes have been made to the methods used for non-destructive examination and to the method of interpreting and sentencing the depth of gas pores.

(j)

The previously accepted convention that root slag intrusions be sentenced as undercut has been reintroduced after being inadvertently lost.

The above list of changes is not intended to be complete. Users of the Standard should not rely upon the list in order to ascertain whether there have been changes made to the previous version of the Standard. Statements expressed in mandatory terms in notes to tables and figures are deemed to be requirements of this Standard.

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CONTENTS Page SECTION 1 SCOPE AND GENERAL 1.1 SCOPE ........................................................................................................................ 8 1.2 QUALIFICATION AND APPROVAL........................................................................ 9 1.3 RETROSPECTIVITY................................................................................................ 10 1.4 REFERENCED DOCUMENTS ................................................................................ 11 1.5 DEFINITIONS .......................................................................................................... 11 1.6 ROUNDING OF NUMBERS .................................................................................... 15 1.7 CARBON EQUIVALENT (CE) ................................................................................ 15 SECTION 2 MATERIALS 2.1 GENERAL ................................................................................................................ 16 2.2 CONSUMABLES...................................................................................................... 16 SECTION 3 POST-WELD HEAT TREATMENT AND POST-WELD COOLING 3.1 POST-WELD HEAT TREATMENT......................................................................... 18 3.2 POST-WELD COOLING .......................................................................................... 18 SECTION 4 WELDING POSITIONS 4.1 DESIGNATION ........................................................................................................ 19 4.2 LIMITS OF QUALIFIED POSITIONS ..................................................................... 19

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SECTION 5 QUALIFICATION OF A WELDING PROCEDURE 5.1 PURPOSE OF QUALIFYING A WELDING PROCEDURE.................................... 23 5.2 TYPES OF WELDS .................................................................................................. 23 5.3 DOCUMENTATION AND APPROVAL.................................................................. 24 5.4 METHODS OF QUALIFICATION........................................................................... 24 5.5 WELDING PROCEDURE SPECIFICATION........................................................... 26 5.6 CHANGES IN A WELDING PROCEDURE ............................................................ 27 5.7 TEST PIECE SIZE .................................................................................................... 27 5.8 TEST PIECE MATERIAL ........................................................................................ 27 5.9 PREPARATION AND ASSEMBLY OF TEST PIECES........................................... 28 5.10 TEST CONDITIONS................................................................................................. 28 5.11 SUPERVISION OF THE TEST WELD .................................................................... 28 5.12 IDENTIFICATION OF THE TEST WELD............................................................... 28 SECTION 6 ASSESSMENT OF THE TEST WELD TO QUALIFY A WELDING PROCEDURE 6.1 METHOD OF ASSESSMENT .................................................................................. 35 6.2 VISUAL EXAMINATION........................................................................................ 35 6.3 NON-DESTRUCTIVE EXAMINATION.................................................................. 35 6.4 DESTRUCTIVE TESTS............................................................................................ 35 6.5 REPEATED TESTS .................................................................................................. 39 6.6 RECORD OF RESULTS ........................................................................................... 39 6.7 PERIOD OF VALIDITY ........................................................................................... 39 6.8 DISQUALIFICATION OF A QUALIFIED WELDING PROCEDURE.................... 39 SECTION 7 QUALIFICATION OF A WELDER OPERATOR 7.1 PURPOSE OF QUALIFYING A WELDER.............................................................. 41 7.2 CATEGORIES AND SCOPE OF WELDER OR OPERATOR QUALIFICATION .. 41 7.3 METHODS OF QUALIFICATION........................................................................... 41

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7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12

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QUALIFICATION BY TESTING............................................................................. 41 ESSENTIAL VARIABLES FOR WELDERS AND OPERATOR ............................ 42 TEST PIECE ............................................................................................................. 43 ASSEMBLY OF TEST PIECES................................................................................ 44 AUTOMATIC WELDING EQUIPMENT................................................................. 44 CATEGORIES OF TEST WELDS............................................................................ 44 MAKING A TEST WELD ........................................................................................ 44 SUPERVISION OF A TEST WELD ......................................................................... 44 IDENTIFICATION OF A TEST WELD ................................................................... 45

SECTION 8 ASSESSMENT OF TEST WELDS FOR WELDER OR OPERATOR QUALIFICATION 8.1 METHOD OF ASSESSMENT .................................................................................. 46 8.2 VISUAL EXAMINATION........................................................................................ 46 8.3 NON-DESTRUCTIVE EXAMINATION.................................................................. 46 8.4 REPEATED TEST .................................................................................................... 46 8.5 RECORD OF RESULTS ........................................................................................... 46 8.6 CLASSIFICATION OF CATEGORIES OF WELDS................................................ 47 8.7 PORTABILITY OF A WELDER’S OR OPERATOR’S QUALIFICATION ............ 47 SECTION 9 WELDER OR OPERATOR QUALIFICATION AND DISQUALIFICATION 9.1 RECIPROCITY OF A WELDER’S OR OPERATOR’S QUALIFICATION ............ 48 9.2 PERIOD OF VALIDITY ........................................................................................... 48 9.3 QUALIFICATION RECORD.................................................................................... 48 9.4 DISQUALIFICATION OF A WELDER’S OR OPERATOR’S QUALIFICATION . 48

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SECTION 10 DESIGN OF A WELDED JOINT 10.1 GENERAL ................................................................................................................ 49 10.2 BUTT WELDS BETWEEN COMPONENTS OF EQUAL NOMINAL WALL THICKNESS ............................................................................................................. 49 10.3 BUTT WELDS BETWEEN COMPONENTS OF UNEQUAL NOMINAL WALL THICKNESS ............................................................................................................. 49 10.4 REINFORCEMENT OF A BUTT WELD ................................................................. 49 10.5 FILLET WELD ......................................................................................................... 49 10.6 WELDING OF THREADED JOINTS....................................................................... 50 10.7 REINFORCEMENT OF A WELDED BRANCH CONNECTION............................ 50 10.8 REINFORCEMENT OF MULTIPLE OPENINGS.................................................... 50 10.9 FORGED BRANCH FITTING.................................................................................. 50 10.10 FABRICATED ELBOW OR BEND.......................................................................... 50 10.11 EFFECT OF COMPONENTS UPON PIG PASSAGE .............................................. 50 10.12 OFFSET OF LONGITUDINAL WELDS .................................................................. 51 10.13 DISTANCE BETWEEN WELDS.............................................................................. 51 SECTION 11 PRODUCTION WELDS 11.1 WELDING PROCESS............................................................................................... 54 11.2 WELDING EQUIPMENT ......................................................................................... 54 11.3 WELDER AND WELDING PROCEDURE .............................................................. 54 11.4 SUPERVISION OF WELDING ................................................................................ 54 11.5 SAFETY IN WELDING............................................................................................ 54 11.6 STORAGE AND HANDLING OF ELECTRODES, FILLER RODS AND FLUXES.................................................................................................................... 54 11.7 WELDING IN ADVERSE CLIMATE CONDITIONS.............................................. 54 11.8 PREPARATION FOR WELDING ............................................................................ 55 11.9 METHOD OF MAKING THE WELD PREPARATION........................................... 55 11.10 ACCURACY OF ALIGNMENT ............................................................................... 55

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11.11 LINE-UP CLAMP ..................................................................................................... 55 11.12 TACK WELDS.......................................................................................................... 55 11.13 WORKING CLEARANCE........................................................................................ 55 11.14 PLACEMENT OF WELD PASSES .......................................................................... 55 11.15 ARC STRIKE AND ARC BURN .............................................................................. 56 11.16 CLEANING............................................................................................................... 56 11.17 PEENING .................................................................................................................. 56 11.18 INSERT PATCHING ................................................................................................ 56 11.19 PREHEAT AND INTERPASS TEMPERATURE..................................................... 56 11.20 POST-WELD HEAT TREATMENT......................................................................... 56 11.21 IDENTIFICATION OF A PRODUCTION WELD.................................................... 56

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SECTION 12 WELDING AND CUTTING ON A PIPELINE AFTER COMMISSIONING OR AFTER HYDROSTATIC TESTING 12.1 GENERAL ................................................................................................................ 57 12.2 SAFETY.................................................................................................................... 57 12.3 HOT REPAIR OF LEAKING GAS-FILLED PIPELINES ........................................ 57 12.4 WHERE GAS IS NOT ESCAPING........................................................................... 58 12.5 PIPELINES CONTAINING PETROLEUM FLUIDS OTHER THAN LEAN NATURAL GAS ....................................................................................................... 58 12.6 QUALIFICATION OF WELDER(S) ........................................................................ 58 12.7 QUALIFICATION OF SUPERVISORS AND INSPECTORS.................................. 58 12.8 FIT-UP BEFORE WELDING AND CUTTING ........................................................ 58 12.9 EXAMINATION AND TESTING ............................................................................ 58 12.10 CRITERIA OF ACCEPTANCE ................................................................................ 59 SECTION 13 WELDING ONTO AN IN-SERVICE PIPELINE 13.1 GENERAL—PIPELINE CONTAINING FLAMMABLE OR PRESSURIZED FLUID ....................................................................................................................... 60 13.2 PRECAUTIONS TO BE UNDERTAKEN BEFORE IN-SERVICE WELDING....... 60 13.3 LINING ..................................................................................................................... 60 13.4 SAFETY.................................................................................................................... 60 13.5 INSPECTION BEFORE WELDING ......................................................................... 60 13.6 ULTRASONIC EXAMINATION BEFORE WELDING........................................... 61 13.7 WELDING CONSUMABLES................................................................................... 61 13.8 HEAT INPUT............................................................................................................ 61 13.9 QUALIFICATION OF WELDING PROCEDURES ................................................. 61 13.10 WELDING SEQUENCE ........................................................................................... 62 13.11 QUALIFICATION OF WELDER(S) ........................................................................ 64 13.12 QUALIFICATION OF SUPERVISORS AND INSPECTORS.................................. 64 13.13 FIT-UP BEFORE WELDING ................................................................................... 64 13.14 EXAMINATION OF TESTING................................................................................ 64 13.15 CRITERIA OF ACCEPTANCE ................................................................................ 64 13.16 WELDING OF TEST ASSEMBLY........................................................................... 64 SECTION 14 ASSESSMENT OF PRODUCTION WELDS AND REPAIR WELDS 14.1 GENERAL ................................................................................................................ 65 14.2 QUALIFICATION OF PERSONNEL ....................................................................... 65 14.3 RESPONSIBILITIES ................................................................................................ 65 14.4 METHODS OF EXAMINATION ............................................................................. 65 SECTION 15 VISUAL EXAMINATION 15.1 PURPOSE ................................................................................................................. 66 15.2 METHOD OF EXAMINATION ............................................................................... 66 15.3 EXTENT OF VISUAL EXAMINATION.................................................................. 66

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15.4 CRITERIA OF ACCEPTANCE ................................................................................ 66 15.5 UNDERCUT DEPTH MEASUREMENT ................................................................. 66 SECTION 16 NON-DESTRUCTIVE EXAMINATION 16.1 PURPOSE ................................................................................................................. 68 16.2 ORGANIZATIONS UNDERTAKING NON-DESTRUCTIVE EXAMINATION .... 68 16.3 QUALIFICATIONS OF PERSONNEL..................................................................... 68 16.4 METHODS................................................................................................................ 68 16.5 AMOUNT OF NON-DESTRUCTIVE EXAMINATION.......................................... 68 16.6 EXEMPTION FROM RADIOGRAPHIC OR ULTRASONIC EXAMINATION ..... 69 16.7 TIMING OF NON-DESTRUCTIVE EXAMINATION............................................. 70 SECTION 17 RADIOGRAPHIC EXAMINATION 17.1 GENERAL ................................................................................................................ 71 17.2 SAFETY AND PROTECTION FROM IONIZING RADIATION ............................ 71 17.3 DENSITY .................................................................................................................. 71 17.4 IMAGE QUALITY.................................................................................................... 71 17.5 UNDERCUT DEPTH MEASUREMENT ................................................................. 72 17.6 GAS PORE DEPTH MEASUREMENT.................................................................... 73 17.7 INTEPRETATION AND ASSESSMENT OF RADIOGRAPHS............................... 74 17.8 CRITERIA OF ACCEPTANCE ................................................................................ 75 17.9 REPORT OF RADIOGRAPHIC EXAMINATION ................................................... 75 17.10 RETENTION OF RADIOGRAPHS .......................................................................... 75 SECTION 18 QUALIFYING A RADIOGRAPHIC PROCEDURE 18.1 RADIOGRPHIC PROCEDURE ................................................................................ 76 18.2 METHOD OF QUALIFYING THE RADIOGRAPHIC PROCEDURE .................... 76 18.3 TEST CONDITIONS................................................................................................. 77 18.4 RADIOGRAPHIC PROCEDURE SPECIFICATION DOCUMENTATION............. 77 18.5 PERIOD OF VALIDITY ........................................................................................... 77 SECTION 19 ULTRASONIC EXAMINATION 19.1 MANUAL ULTRASONIC EXAMINATION ........................................................... 78 19.2 MECHANIZED ULTRASONIC EXAMINATION................................................... 79

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SECTION 20 MAGNETIC PARTICLE TESTING 20.1 PURPOSE ................................................................................................................. 82 20.2 METHOD .................................................................................................................. 82 20.3 QUALIFICATION OF PERSONNEL ....................................................................... 82 20.4 CRITERIA OF ACCEPTANCE ................................................................................ 82 SECTION 21 DYE-PENETRANT TESTING 21.1 PURPOSE ................................................................................................................. 83 21.2 METHOD .................................................................................................................. 83 21.3 QUALIFICATION OF PERSONNEL ....................................................................... 83 21.4 CRITERIA OF ACCEPTANCE ................................................................................ 83 SECTION 22 CRITERIA OF ACCEPTANCE FOR GIRTH WELD DISCONTINUITIES 22.1 GENERAL ................................................................................................................ 84 22.2 TIER 1 CRITERIA—WORKMANSHIP STANDARD ............................................. 87 22.3 TIER 2 CRITERIA—GENERALIZED FITNESS-FOR-PURPOSE STANDARD.... 96 22.4 TIER 3 CRITERIA—ENGINEERING CRITICAL ASSESSMENT ....................... 101

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SECTION 23 REPAIR OF AN UNACCEPTABLE WELD 23.1 GENERAL .............................................................................................................. 102 23.2 REPAIR METHODS ............................................................................................... 102 23.3 QUALIFICATION OF THE REPAIR WELDING PROCEDURE .......................... 102 23.4 INSPECTION .......................................................................................................... 102 23.5 CRITERIA OF ACCEPTANCE .............................................................................. 102 SECTION 24 REMOVAL OF AN ARC BURN 24.1 GENERAL .............................................................................................................. 103 24.2 REPAIR BY GRINDING ........................................................................................ 103 24.3 METHOD OF INSPECTION .................................................................................. 103 24.4 CRITERIA OF ACCEPTANCE .............................................................................. 103 24.5 CLEANING AFTER TESTING .............................................................................. 103 SECTION 25 CUTTING OUT AN UNACCEPTABLE WELD OR AN ARC BURN........... 104 SECTION 26 RECORDS....................................................................................................... 105

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APPENDICES A ITEMS REQUIRING APPROVAL ......................................................................... 106 B LIST OF REFERENCED DOCUMENTS ............................................................... 108 C SELECTION AND SPECIFICATION OF CELLULOSIC WELDING ELECTRODES........................................................................................................ 111 D GUIDANCE ON ‘GMAW’ WELDING CONSUMABLES FOR MECHANIZED PIPELINE GIRTH WELDS .................................................................................... 115 E AVOIDANCE OF HYDROGEN ASSISTED COLD CRACKING (HACC)........... 116 F EXAMPLE OF WELD PROCEDURE SPECIFICATION FORM .......................... 120 G EXAMPLE OF WELDING PROCEDURE QUALIFICATION RECORD FORM . 122

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STANDARDS AUSTRALIA Australian Standard Pipelines—Gas and liquid petroleum Part 2: Welding

SECT ION

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SCOPE

AND

GENERA L

1.1 SCOPE This Standard specifies the minimum requirements for materials, welding consumables, welding processes, weld preparations, qualifications of welding procedures and personnel, and fabrication and inspection requirements for the construction and maintenance welding of carbon and carbon-manganese steel pipelines down to 3.2 mm wall thickness designed and constructed in accordance with AS 2885.1. The welding of corrosion-resistant alloy steel pipelines, or pipelines with wall thickness less than 3.2 mm, is not precluded but is not expressly covered by this Standard. The welding of such pipelines has to be given special consideration. The welding may be done by a manual metal arc, submerged arc, gas tungsten arc, gas metal arc, flux cored arc, oxyacetylene, or by a combination of these using a manual, semiautomatic, or automatic welding technique or a combination of these techniques. The welds may be produced by position or roll welding or by a combination of position and roll welding.

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Other processes may be submitted for inclusion in the Standard upon provision of the following information: (a)

A description of the welding process.

(b)

A proposal on the essential variables.

(c)

A typical welding procedure qualification record and a welding procedure specification.

(d)

Weld inspection methods.

(e)

Types of weld discontinuities and their proposed acceptance limits.

(f)

Repair procedures.

This Standard is applicable to the welding of joints in or on pipelines, and the field welding of pipeline assemblies. This Standard may be applied to the factory fabrication of pipeline assemblies manufactured from pipes and fittings. See Figure 1.1 for examples. NOTE: The welding of fittings may present special difficulties when using typical pipeline welding procedures (see Appendix E).

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(a) M a i n l i n e va l ve a s s e m b l y

( b) Ins u l ati n g j o i nt a s s e m b l y

(c) S c ra p e r tra p a s s e m b l y

(d ) Pi g g i n g b a r te e a s s e m b l y

(e) A n c h o r f l a n g e

FIGURE 1.1 EXAMPLE OF ASSEMBLIES THAT MAY BE WELDED IN ACCORDANCE WITH THIS STANDARD

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1.2 QUALIFICATION AND APPROVAL Welding shall be performed by qualified personnel, in accordance with documented qualified and approved welding procedures. Items requiring approval in accordance with this Standard are listed in Appendix A. Activities undertaken within the scope of this Standard shall be directed by a pipeline licensee appointed for the purpose of giving approvals as defined in this Standard. The process for any delegation of the pipeline licensee’s power shall be in accordance with Figure 1.2.

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New Project

Pipeline licensee approval

Authority to approve delegated

Yes (See Note)

Contractor

No

3rd party

Audit

Pipeline licensee approved

NOTES: 1

The use of AS/NZS ISO 3834.1 and AS/NZS ISO 3834.2 is recommended when the authority to approve is delegated.

2

The audit shall be conducted on behalf of the pipeline licensee. It may be conducted by a third party. The audit shall address the items listed in Appendix A. FIGURE 1.2 APPROVAL PROCESS

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It is not intended that this Standard be applied to the following: (a)

Station pipework as defined in AS 2885.1.

(b)

Longitudinal welds or spiral welds made during the manufacture of a pipe or a component.

(c)

Underwater welding.

(d)

Hyperbaric welding.

1.3 RETROSPECTIVITY It is not intended that this Standard be applied retrospectively to existing installations. Welding procedures complying with and welder qualifications in accordance with the appropriate previous editions of this Standard may continue to be used for the maintenance of existing installations. New welding procedures and new welding qualifications shall be qualified in accordance with this Standard.  Standards Australia

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1.4 REFERENCED DOCUMENTS A list of the documents referred to in this Standard is given in Appendix B. 1.5 DEFINITIONS For the purpose of this Standard, the definitions given below apply. 1.5.1 Accessory A component of a pipeline other than a pipe, valve, or fitting, but including a relief device, a pressure-containing item, hanger, support, and all other items necessary to make a pipeline operative whether or not such items are specified by the Standard. 1.5.2 Approved and approval Approved by the pipeline licensee and includes obtaining the approval of the relevant statutory authority where this is legally required. NOTE: Approval requires a conscious act and is given in writing.

1.5.3 Burn-off rate The ratio of length of electrode consumed to the length of weld pass deposited. Burn-off rate is proportional to the heat input, divided by the square of the electrode core wire diameter. NOTE: WTIA Technical Note 1 provides information relating burn-off rate to heat input

1.5.4 Component Any part of a pipeline other than a pipe. 1.5.5 Construction All activities required to fabricate, construct and test a pipeline, and to restore the right of way. 1.5.6 Defect A discontinuity or imperfection of sufficient magnitude to warrant rejection on the basis of the requirements of this Standard. 1.5.7 Design temperatures The range of the metal temperatures to be expected in construction, testing and normal operation. 1.5.8 Diameter The outside diameter nominated in the material order, ignoring the manufacturing tolerance provided in the specification under which the pipe was manufactured. Accessed by GHD PTY LTD on 05 Aug 2009

1.5.9 Discontinuity A generic term for material imperfections (see Clause 1.5.21), which includes defects (see Clause 1.5.6) and non-rejectable irregularities. 1.5.10 Engineering critical assessment (ECA) A formal process for the assessment of structures containing discontinuities, in order to determine whether the structure is fit for purpose. NOTE: The process involves the use of fracture mechanics and requires consideration of the discontinuity, the stress, and the material properties for the likelihood of failure arising from fracture, plastic collapse, fatigue, buckling, creep, corrosion/erosion, and leakage.

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1.5.11 Engineering design The detailed design of a pipeline system, developed from process and mechanical requirements, complying with the requirements of this Standard and including all necessary specifications, drawings, and supporting documents. 1.5.12 Environment The complex of climatic, demographical, geotechnical, oceanographic, and biotic factors that acts on a pipeline influencing the design, construction, testing, inspection, operation, and maintenance. 1.5.13 Essential variable and non-essential variable 1.5.13.1 Essential variable Variable in which a change outside specified limits requires requalification of welding procedure or welder or operator qualification. 1.5.13.2 Non-essential variable Variable in which a change outside specified limits does not require requalification of the welding procedure. NOTE: Non-essential variables are those Items in Table 5.4(A) that do not appear in the list of essential variables in Table 5.4(B).

1.5.14 Fitting A component, including any associated flanges, bolts, and gaskets, used to join pipes, to change the direction or diameter of a pipeline to provide a branch, or to terminate a pipeline. 1.5.15 Fluid Any vapour, liquid, gas, or mixture thereof. 1.5.16 Gas Any hydrocarbon gas or mixture of gases, possibly in combination with liquid petroleum condensates or water. 1.5.17 Heat input (arc energy) Q=

EI 60 × V 1000

where Q = welding energy input, in kilojoules per millimetre

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E = arc voltage, in volts (RMS value for a.c.) I = welding current, in amperes (RMS value for a.c.) V = welding speed, in millimetres per minute NOTE: Both the arc voltage and welding current have to be measured accurately with voltage measured between the electrode holder or contact tube and the work piece.

1.5.18 Hot repair Repair welding on a pipeline containing hydrocarbon gas under controlled conditions with a burning gaseous atmosphere present due to escape of the pipeline contents. 1.5.19 Hot tap A connection made to a pipeline containing hydrocarbon fluid.

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1.5.20 Hydrogen assisted cold cracking (HACC) A form of brittle cracking that occurs at near-ambient temperature in the weld or heat-affected zone or ferritic steel weldments, due to the combined effects of hydrogen arising from welding, together with tensile stress and a susceptible microstructure. NOTE: The time delay after welding at which HACC occurs depends upon the particular circumstances, especially the hydrogen concentration. With low levels of hydrogen it may be 24 h or more.

1.5.21 Imperfection A material discontinuity or irregularity that is detectable by inspection in accordance with this Standard. 1.5.22 Inert gas shielding Shielding gas consisting principally of argon, helium, or a mixture of the two. 1.5.23 In-service welding Welding onto a pressurized product-filled pipeline. 1.5.24 Inspector A person appointed by the pipeline licensee to carry out inspections required by this Standard. 1.5.25 Location class An area classified according to its general geographic and demographic characteristics. 1.5.26 Mainline pipework Those parts of a pipeline between stations, including pipeline assemblies. 1.5.27 Matching (undermatching) The ability of a full scale welded joint containing discontinuities at the limit of the acceptance criteria to match the strength of the pipe and to ensure that under displacementcontrolled loading plastic strains occurs in one or both of the pipes before the weld breaks. 1.5.28 May Indicates— (a)

the existence of an option; and

(b)

a course of action that is permissible within the limits of the Standard.

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1.5.29 Natural gas Gaseous hydrocarbons (mainly methane) from underground deposits, the production of which may be associated with the production of crude petroleum. The gas is described as ‘wet’ or ‘dry’ according to the proportion of readily condensable hydrocarbons, which it contains. This term also applies to the purified product. 1.5.30 Nominal thickness (δN) The thickness nominated in the material order, ignoring the manufacturing tolerance provided in the specification under which the pipe was manufactured. 1.5.31 Non-planar discontinuity Weld discontinuities not included in the planar category, including volumetric discontinuities such as porosity, root concavity, burn through, hollow head, and slag inclusions.

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1.5.32 Pipeline licensee The organization responsible for the design, construction, testing, inspection, operation and maintenance of facilities within the scope of the Standard. 1.5.33 Pig A device that is propelled inside a pipeline by applied pressure. NOTE: Pigs can be of various types, such as gauging pig for checking a pipeline bore, a swabbing pig for cleaning a pipeline, or an intelligent pig for checking wall thickness, deformation or cracking, or the integrity of the coating of a pipeline.

1.5.34 Pig trap (scraper trap) A fabricated component to enable a pig to be inserted into or removed from an operating pipeline. 1.5.35 Pipeline assemblies Assemblies of pipe, valve and fittings that are considered to be integral parts of the pipeline (see AS 2885.1). NOTE: Such assemblies are usually prefabricated off-site.

1.5.36 Planar defect A category of unacceptable weld discontinuities that are assumed to have only two dimensions and which, in fracture mechanics terms, are considered to be equivalent in behaviour to a crack. NOTE: The fitness-for-purpose-based acceptance criteria in Tier 2 of this Standard classify the various discontinuity types into planar and non-planar categories. The workmanship based acceptance criteria in Tier 1 do not require classification of discontinuities according to whether they are planar or non-planar.

1.5.37 Preheat temperature The temperature immediately prior to the commencement of welding. The preheat temperature may be the ambient or pre-existing temperature of the joint, or it may result from the heating of the parent metal in the region of the weld. NOTE: A minimum preheat temperature may be required, for example, to avoid hydrogen cracking in the weld metal or heat-affected zone. A maximum value may also be specified in order to achieve particular levels of toughness and/or strength. It is recommended that preheat be measured at least 75 mm from the weld line.

1.5.38 Pre-tested pipe

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A pipe or a pressure-containing component that has been subjected to a pressure test in accordance with this Standard before being installed in a pipeline and intended to be used for tie-in or maintenance purposes. 1.5.39 Shall Indicates that a statement is mandatory. 1.5.40 Should Indicates a recommendation. 1.5.41 Sour service Piping conveying crude oil or a natural gas containing hydrogen sulfide and an aqueous liquid phase in a concentration that can affect materials. NOTE: The limits defined in NACE MR0175 are deemed, for the purposes of this Standard, to constitute sour service.

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1.5.42 Thickness for design internal pressure (δ dp) The thickness of material, calculated according to the equations in the design section of this Standard, required for the material to be capable of withstanding the design internal pressure. 1.5.43 Weld metal deposition repair Repair method for loss of thickness. NOTE: For example, repairing corrosion defects by surfacing with deposited weld metal whilst the pipeline is in service.

1.5.44 Weldability The ability of a metal to be welded under given fabrication conditions in a specific weldment, and to perform satisfactorily in service. 1.5.45 Welding operator A person who operates automatic welding equipment 1.5.46 Weldolet An integrally reinforced sit-on branch fitting that is designed and manufactured according to a nominated Standard. NOTE: ‘Weldolet’ also refers to similar integrally reinforced sit-on/set-in branch fittings (e.g., threadolets, sockolets, latrolets, elbowlets, sweepolets).

1.5.47 Yield strength Either— (a)

the specified minimum yield strength (SMYS) to which the pipe is purchased; or

(b)

the actual yield strength (AYS) being the hoop stress determined from the pressure at the strength test end point as specified in this Standard.

NOTE: The yield strength may be represented by a material grade, e.g., X60 (Yield strength 413 MPa).

1.6 ROUNDING OF NUMBERS An observed or calculated value shall be rounded to the nearest unit in accordance with AS 2706. 1.7 CARBON EQUIVALENT (CE)

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For the purpose of this Standard, the carbon equivalent (CE) shall be calculated in accordance with the International Institute of Welding (IIW) formula, i.e., CE = C +

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Mn Cr + Mo+V Cu+Ni + + 6 5 15

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S E C T I ON

2

M A T E R I A L S

2.1 GENERAL The requirements of this Section are applicable to the welding of materials that comply with AS 2885.1. 2.2 CONSUMABLES 2.2.1 Electrodes for manual metal-arc welding Welding electrodes for manual metal-arc welding shall comply with the Standards listed in Table 2.2.1, as appropriate. The following should be taken into account for manual arc welding electrodes: (a)

Lower strength electrodes (see welding process column in Table 2.2.1) should be used for welding of all passes for pipe and components in material up to and including grade X60.

(b)

Unless it can be shown that it is difficult to meet the required mechanical properties (see Clause 22.3.1(c)), lower strength electrodes should be used for the first pass, when welding pipe and components of material greater than grade X60.

(c)

Electrodes for manual metal-arc welding should be selected and specified in accordance with Appendix C.

2.2.2 Wires for automatic welding Wires for automatic welding shall comply with the Standards listed in Table 2.2.1, as appropriate. NOTE: The selection of wires for automatic welding should take into account the information given in Appendix D.

2.2.3 Storage and handling of consumables Consumables shall be stored and handled as follows: (a)

Electrodes—in accordance with one or more of the following: (i)

Recommendations of the manufacturer.

(ii)

Requirements of the relevant Standard.

(iii) Recommendations in WTIA Technical Note 3.

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(b)

Filler rods and fluxes—in accordance with one or more of the following: (i)

Recommendations of the manufacturer.

(ii)

Requirements of the relevant Standard.

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AS 2885.2—2007

TABLE 2.2.1 WELDING CONSUMABLES Welding process

Standard

Electrode type

Remarks

AS/NZS 4855

Cellulose MMA

Note 6

ANSI/AWS A5.1

—

—

AS/NZS 4857

Cellulose MMA

Note 6

ANSI/AWS A5.5

—

—

AS/NZS 4855

Basic coated MMA

—

—

ANSI/AWS A5.1

—

—

—

AS/NZS 4857

Basic coated MMA

—

—

ANSI/AWS A5.5

—

—

AS/NZS 4857

Basic coated MMA

—

ANSI/AWS A5.5

—

—

AS 1858.1

Fused or bonded

Note 1

ANSI/AWS A5.17

—

—

AS/NZS 1167.2

—

—

ANSI/AWS A5.18 ANSI/AWS A5.28

—

—

AS/NZS 2717.1

Solid wire

Note 2 and 5

—

ANSI/AWS A5.18

—

—

—

ANSI/AWS A5.28

—

—

Flux cored arc welding

AS/NZS ISO 17632

Gas-shielded flux-cored

Note 3

—

AS/NZS ISO 17632

Self-shielded flux-cored

Note 3

—

ANSI/AWS A5.20

Gas-shielded flux-cored

Note 4

—

ANSI/AWS A5.20

Self-shielded flux-cored

Note 4

—

ANSI/AWS A5.28

Self-shielded flux-cored

Note 4

Manual metal-arc welding using lower strength cellulose electrodes — Manual metal-arc welding using medium strength cellulose electrodes — Manual metal-arc welding using lower strength hydrogen-controlled electrodes

Manual metal-arc welding using medium strength hydrogen-controlled electrodes — Submerged arc welding — Gas tungsten-arc welding — Gas metal-arc welding

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NOTES: 1

Any combination of these electrodes and fluxes may be used to qualify a procedure. Each combination is to be identified by its complete classification number (e.g., F6A2-EM12K or F7A1-EL12 as specified in ANSI/AWS A5.17, EL12-FMM-W501 as specified in AS 1858.1).

2

Any combination of electrodes and gases may be used to qualify a procedure. Each combination is to be identified by its complete classification number (e.g., ER 70S-6 as specified in ANSI/AWS A5.18, ES2GC-W500H as specified in AS/NZS 2717.1), and each shielding gas to be specified by brand name or mix analysis.

3

Any combination of electrodes (with or without gas) may be used to qualify a procedure. Consumables are to be identified by the complete classification number (e.g., ETP-GN-W402). Where a shielding gas is used, this shall be specified by brand name or mix analysis.

4

Any combination of electrodes may be used to qualify a procedure. Consumables are to be identified by the complete classification number (e.g., root pass E71T-GS, other passes E71T8-K2).

5

See also Appendix D.

6

See also Appendix C.

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3 P O S T- W E L D H E A T T RE A T M E N T AND POST-WE LD CO O L I N G

3.1 POST-WELD HEAT TREATMENT Components that comply with a nominated Standard normally do not require post-weld heat treatment, but, where determined to be necessary under the provisions of Clause 5, postweld heat treatment shall be carried out in accordance with AS 1210, or an approved method. 3.2 POST-WELD COOLING The use of deliberate accelerated cooling of a weld shall be permissible provided— it shall not be used before the weld has cooled to 300°C; and

(b)

if it used before the weld has cooled to 100°C, it shall be regarded as an essential variable and shall be qualified as an item of the welding procedure.

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(a)

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SECT ION

4

WE LD I N G

AS 2885.2—2007

POS IT I O NS

4.1 DESIGNATION Positions for test welds shall be designated as shown in Figure 4.1, and shall be within ±5° of the nominal position. Where the position of a production weld cannot be related to one or more of the designated weld positions, a special test position shall be used. 4.2 LIMITS OF QUALIFIED POSITIONS The position used in the welding procedure qualification test and welder qualification tests shall also qualify other positions as shown in Table 4.2(A).

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For reciprocity of weld types for welder qualification see Table 4.2(B).

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TABLE 4.2(A) POSITIONS FOR WELDING PROCEDURE AND WELDER QUALIFICATION TESTS FOR BUTT, FILLET, SLEEVE AND BRANCH WELDS ON PIPE AND RECIPROCITY OF TYPES OF WELD AND POSITION (see Note 3) Type of weld and position qualified (see Note 2)

Qualification test on pipe Type of weld

Butt

Fillet

Branch

Sleeve

Horizontal (flat)

1G

—

—

—

Vertical— fixed

Horizontal

1G and 2G

2F and 2FR

—

—

5G

Horizontal— fixed

Multiple

1G and 5G

Any

—

—

6G

Inclined 45°— fixed

Multiple

Any

Any

—

—

2G and 5G1 (see Note 1)

Vertical— fixed, and horizontal— fixed

Horizontal and multiple

Any

Any

—

—

2F

Vertical— fixed

Horizontal

—

2F and 2FR

—

—

2FR

Horizontal— rotated

Horizontal

—

2FR

—

—

4F

Vertical— fixed

Horizontal (overhead)

—

2F, 2FR, and 4F

—

—

5F

Horizontal— fixed

Multiple

—

Any

—

5F (sleeve)

2B

315° to 45°

Horizontal (flat)

1G and 2G

2F and 2FR

2B

—

4B

135° to 225°

Horizontal (overhead)

1G and 2G 2F, 2FR, and 4F

2B and 4B

—

5B

45° to 135°

Multiple

1G and 2G

Any

Any

—

5F

Horizontal— fixed

Multiple

—

Any

—

Any

1G Plate

Downhand butt plate

Downhand (flat)

—

Any

—

1G Plate

2G Plate

Horizontal butt plate

Horizontal

—

Any

—

1G and 2G Plate

4G Plate

Overhead butt plate

Overhead

—

Any

—

Any

Description Butt (girth)

Fillet

Branch (see Note 4)

Sleeve

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Position of axis

Symbol

Pipe

Weld

1G

Horizontal— rotated

2G

NOTES: 1

Qualified by separate tests for each position or a combination of 2G and 5G test welds.

2

Refer to Figure 4.1 for the types of welds and positions.

3

Table 4.2(B) gives reciprocity of weld types for welder qualification (see also Clause 8.6).

4

Tee butt welds qualify fillet welds as listed. Fillet welds do not qualify tee butt welds. Butt welds qualified by branch connection weld procedure qualification tests shall be restricted to the types of butt welds involved in the branch connection (see also Clause 10.9).

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AS 2885.2—2007

TABLE 4.2(B) RECIPROCITY OF WELD TYPES FOR WELDER QUALIFICATION Weld types qualified in welder qualification test

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Type number of weld

Weld type number qualified without further testing (Note 1)

Description of weld

1

1G butt weld with pipe horizontal and rotated

1

—

—

—

—

—

—

—

—

—

2

2G butt weld with pipe vertical and fixed

1

2

—

—

—

—

—

—

—

—

3

5G butt weld with pipe horizontal and fixed

1

—

3

—

—

—

—

8

—

—

4

2G and 5G butt weld or a 6G butt weld with pipe inclined 45° and fixed

1

2

3

4

—

—

—

8

—

—

5

2G and 5G butt weld or 6G butt weld plus mark out, cut, fit and weld a reinforced siton tee-butt branch ≥D/3 in position 5B

1

2

3

4

5

6

7

8

9

—

6

Mark out, cut, fit and weld a reinforced sit-on tee-butt pipe branch ≥D/3 in position 5B

—

—

—

—

—

6

7

8

9

—

7

Mark out, cut, fit and weld in position 5B either a sit-on bevelled end forged fitting or a sit-on tee-butt pipe branch

1

2

—

—

—

—

7

8

9

—

8

Make a fillet weld in position 5F on the socket weld end of a forged fitting, a socketed pipe, a slip-on flange, a bracket, a pad or a plain end sit-on branch

—

—

—

—

—

—

—

8

—

—

9

Mark out, cut, fit, and weld in position 5B either a forged set-in branch or a non-reinforced set-in pipe branch

1

2

—

—

—

—

7

8

9

—

10

Fit and weld either a circumferential split sleeve or a tee fitting with a longitudinal single V butt weld with backing strip and ends fillet-welded

—

—

—

—

—

—

—

8

—

10

NOTES: 1

For reciprocity of welding positions, see Table 4.2(A) (see also Clause 8.6.)

2

Qualified by separate tests in each position or a combination of 2G and 5G test welds.

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Type of weld

Welding positions

Butt weld

Axis of pipe horizontal Pipe rotated Flat position, 1G

Axis of pipe vertical Axis of pipe horizontal Pipe fixed Pipe fixed Horizontal position, 2G Multiple position, 5G

Axis of pipe inclined 45° Pipe fixed Multiple position, 6G

Axis of pipe horizontal Pipe rotated Horizontal position, 2FR

Axis of pipe vertical Axis of pipe horizontal Pipe fixed Pipe fixed Horizontal position, 2F Multiple position, 5F

Axis of pipe vertical Pipe fixed Overhead position, 4F

Axis of pipe horizontal Pipe rotated Multiple position, 5F Circumferential fillet

1G Plate with backing strip Longitudinal weld

4G Plate with backing strip Longitudinal weld

Fillet weld

Sleeve/ Stopple fitting weld 2G Plate with backing strip Longitudinal weld

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Branch weld (Including set-in, set-on and ‘-O-let’ type fittings) Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 45° to 135° Multiple position, 5B

Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 135° to 225° Overhead position, 4B

Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 315° to 45° Horizontal position, 2B

FIGURE 4.1 WELD TEST POSITIONS

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SECT ION

5

QUA L I F I C AT I ON P R O CE D U RE

AS 2885.2—2007

O F

A

WE LD I N G

5.1 PURPOSE OF QUALIFYING A WELDING PROCEDURE A welding procedure shall be qualified to demonstrate that the production welds made in accordance with the welding procedure— (a)

have the required mechanical properties such as strength, ductility and hardness;

(b)

are sound, i.e., free from cracks, unacceptable porosity or other defects; and

(c)

are free from the risk of hydrogen assisted cold cracking (HACC).

The basis of the design of the welding procedure for the avoidance of HACC shall be documented in the welding procedure specification. Requirements for the avoidance of HACC, including recommended methods for ‘designing out’ HACC from welding procedures, are given in Appendix E. NOTE: A suitable form of documentation is given in Appendix F.

5.2 TYPES OF WELDS 5.2.1 General The types of welds encountered in petroleum pipeline systems are the following: (a)

Production welds of joints in or on pipelines, field welding of pipeline assemblies and fabrication of pipeline assemblies manufactured from pipes and fittings (see Clause 1.1) (i)

Mainline

(ii)

Tie-in

(iii) Special class (e.g., tie-in weld not subject to pressure testing) (iv)

Repair welds (see Clause 23.2)

(v)

Welds on components

(vi)

Temporary welds used in construction (e.g., test headers)

(b)

In-service welds.

(c)

Welds made in accordance with other standards (e.g., station piping and components to AS 4041).

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5.2.2 Types of welds requiring welding procedure qualification The types of welds requiring welding procedure qualification are the following: (a)

The production welds listed in Clause 5.2.1(a), which shall be qualified by one of the methods listed in Clause 5.4.

(b)

In-service welds, which shall be qualified in accordance with Clauses 12 or 13 of this Standard.

(c)

Repair welds, which shall be qualified in accordance with Clause 23 of the Standard.

(d)

Welds made in accordance with other standards, which shall be qualified in accordance with the relevant Standard.

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5.3 DOCUMENTATION AND APPROVAL Regardless of the method of qualification, the welding procedure shall be documented in a welding procedure specification (WPS) in accordance with Clause 5.4, and shall be approved. NOTE: A suitable form of documentation is given in Appendix F.

5.4 METHODS OF QUALIFICATION 5.4.1 General There are four methods of qualifying a welding procedure, as follows: (a)

Qualification by testing.

(b)

Qualification by documentation of previous testing and approval.

(c)

Qualification by prequalification without testing.

(d)

Qualification by the use of supervision.

A flow chart illustrating these methods is shown in Figure 5.4.1. NOTE: Developing a repair procedure at the same time as the main procedure is good practice.

Q u a l i f i c ati o n by te sti n g

Q u a l i f i c ati o n by d o c u m e ntati o n of p rev i o u s te s ti n g

Q u a l i f i c ati o n by p re - q u a l i f i c ati o n w i th o u t te s ti n g

Q u a l i f i c ati o n by u s e of super vision

R e c o rd of p rev i o u s l y a p p rove d W P Q R

C o m p l i a n c e w i th s et c o n d i ti o n s (C l au s e 5.3)

En g i n e e r i n g a s s e s s m e nt / j u s ti f i c ati o n

A p p rova l of we l d i n g p ro c e d u re p ro p o s a l ( W PP)

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R e c o rd of s u c c e s s f u l p ro c e d u re q u a l i f i c ati o n te st we l d ( W P Q R)

We l d i n g p ro c e d u re s p e c i f i c ati o n ( W PS)

A p p rova l

FIGURE 5.4.1 FLOW CHART SHOWING QUALIFICATION OF PROCEDURE

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AS 2885.2—2007

5.4.2 Qualification by testing Where a welding procedure is to be qualified by testing, a sufficient number of test welds, having regard to the range of essential and non-essential variables in the welding procedure specification, and the intended use of the procedure shall be made in accordance with Clauses 5.5 to 5.11 and the proposed welding procedure, and shall be examined, tested and assessed in accordance with Clause 6. Where the procedure is intended to qualify a range or ranges of essential variables that are broader than the permissible limits given in Table 5.4.2(B), it shall be necessary to qualify the procedure using more than one test weld with values of the essential variables chosen to span the qualified range taking into account the tolerances in Table 5.4.2(B). The specified ranges of the essential variables may be extended at any time by the welding and testing of additional test welds. Such changes shall be documented in a revised welding procedure specification. The ranges of non-essential variables may be extended by documentation only. NOTE: The welding procedure qualification test may also be used to qualify a welder (see Clause 7.3(B)).

Where the weld meets all the criteria of acceptance, and the results have been recorded (see Clause 6.6), the welding procedure shall be qualified. 5.4.3 Qualification by documentation of previous testing and approval Part or all of the welding procedure qualification tests may be waived on production of approved documentary evidence that similar welds have been made and tested, and that the welding procedure has been qualified previously in accordance with one of the following: (a)

This Standard or any of its previous editions.

(b)

AS 1697.

(c)

AS 4041 or AS 1210 through AS 3992.

(d)

ANSI ASME B31.3, ANSI B31.4 or ASME B31.8 through ASME IX.

(e)

ANSI API 1104.

(f)

DNV OS F101 or AS 2885.4

This method of qualification shall apply only to Tier 1 defect acceptance criteria as described in Clause 22. For new pipeline, the essential variables of this Standard shall apply. For the application of previously qualified procedures to existing pipeline systems, the essential variables applicable to the previous qualified procedure may be applied.

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5.4.4 Qualification by prequalification without testing This method of qualification is not applicable to the welding of fittings or welding on live pipelines or where the design minimum temperature is below 0°C. A welding procedure may be qualified by being deemed to be prequalified when the following restrictions are met: (a)

The joints are butt joints between pipes of equal thickness.

(b)

The weld preparation is in accordance with Figure 10.2.

(c)

The pipe diameter is within the range DN 50 to DN 500.

(d)

The pipe thickness is equal to or greater than 4.8 mm and less than 10 mm.

(e)

The pipe grade does not exceed X60 and the carbon equivalent does not exceed 0.40.

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(f)

The welding process is MMAW using E4110 electrodes in the vertical down direction.

(g)

The number of passes is not less than 3.

(h)

The time lapse between starting the root pass and starting the hot pass shall not exceed 8 min.

(i)

The arc energy is not less than 0.5 kJ/mm, or burn-off rate is not less than 1.00 for 3.2 mm electrodes or 0.50 for 4.0 mm electrodes.

(j)

The preheat is not less than that determined by reference to WTIA Technical Note 1.

(k)

The lifting and lowering practice is restricted to ‘normal lifts’ as defined in Appendix E. NOTE: Extreme lifts may be dealt with within this Clause by adhering to the provisions of Paragraph E9.2.2, Appendix E.

(l)

The welds are made by welders qualified in accordance with this Standard.

(m)

All consumables are used within the manufacturer’s recommendations.

Prequalified welding procedures, which are qualified under this Clause, are deemed suitable for use by dint of their long satisfactory use and do not require testing in accordance with Clause 5.4.1. Prequalified welding procedures shall be documented in accordance with Clause 5.2. 5.4.5 Qualification by the use of supervision In special circumstances outside the restrictions of Clause 5.4.4 and where qualification by testing or documentation is not practicable, a limited number of special welds may be made by qualified welders working under the direct and continuous supervision of a qualified welding engineer. NOTE: An example of these special circumstances might be the welding into a pipeline of a large and expensive fitting where it would not be practicable to meet the test weld requirements of this Standard.

The welding engineer shall have formal qualifications in welding engineering, and shall be experienced in the welding of a pipeline, including specifically qualification in the type of welds that are proposed. The welding procedure used for supervised welds shall be documented and shall be approved. The documentation shall include a statement of the qualifications and experience of the welding engineer who will supervise the welds.

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5.5 WELDING PROCEDURE SPECIFICATION The purpose of the welding procedure specification is to document and record the nominal and, where appropriate, average values of the essential and non-essential variables of the welding procedure, and the limits of these variables. Table 5.4.2(A) lists the items that are to be defined for each welding procedure. Table 5.4.2(B) lists the essential variables for qualified welding procedures. Weld passes in a butt weld shall be identified as shown in Figure 5.5. NOTES: 1

The terms essential variable and non-essential variable are defined in Clause 1.5.

2

A welding procedure specification may be presented in any suitable form (written or tabular), that suits the needs of the organization responsible for qualification of the welding procedure. A suitable form for welding procedure detail is given in Appendix F.

3

A suitable form for test weld record is given in Appendix G.

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AS 2885.2—2007

FIGURE 5.5 IDENTIFICATION OF WELD PASSES IN A SINGLE-SIDED BUTT WELD

5.6 CHANGES IN A WELDING PROCEDURE 5.6.1 Change in an essential variable The following shall be observed: (a)

Where a change is made to an essential variable in a qualified welding procedure beyond the qualified range of the welding procedure specification, or the permissible limit in Table 5.4.2(B), whichever is greater, the welding procedure specification shall be changed, and the new procedure shall be qualified.

(b)

Changes beyond the limits in Table 5.4.2(B) may be made without requalification provided the following criteria is met: (i)

The changes are shown by appropriate documentary evidence in the form of an amendment to the qualified welding procedure not to increase the risk of HACC. This evidence should take into account the material in Appendix E and WTIA Technical Note 1.

(ii)

The changes do not involve an increase in carbon equivalent of more than 0.10 above that used for the procedure test weld.

(iii) The amended welding procedure specification is approved. 5.6.2 Change in other than an essential variable Where a change is made to other than an essential variable, the welding procedure specification shall be modified but need not be requalified. 5.7 TEST PIECE SIZE

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The size of the test piece(s) used for welding procedure qualification test welds shall involve at least one complete welded joint of the type for which the procedure is to be qualified, and shall be sufficient to provide the required number of test specimens. 5.8 TEST PIECE MATERIAL The test piece material shall comply with the following: (a)

Test piece material used for welding procedure qualification test welds shall be of the same specification, grade or class, and outside diameter, as will be used in the major part of the production. The wall thickness shall take into account the limits in the essential variables and, where there is a choice, it should preferably be at the upper end of the range qualified.

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(b)

For material grades equal to or greater than X70, the test piece material shall be from the manufacture, and shall have the same nominal composition as the material represented. Combinations of materials from different manufacturers that have been individually qualified do not require separate qualification for the combination (see Table 5.4.2(B) 1 (b)).

(c)

Where a weld is to be made between a material grade less than X70 and another with material grade equal to or greater than X70, a welding procedure qualification test weld made on the higher grade shall qualify the combination.

(d)

Material with a higher carbon equivalent shall be deemed to be valid for a parent metal with a lower carbon equivalent.

5.9 PREPARATION AND ASSEMBLY OF TEST PIECES The joint preparation of test pieces shall be in accordance with the qualified procedure and shall be within the specified dimensional tolerances. The preparation should preferably be made by the same method as will be used in production. Test pieces shall be assembled in the required position so that the weld can be made in accordance with the welding procedure specification. Tack welding shall be carried out as per the welding procedure. 5.10 TEST CONDITIONS Subject to the requirements of Appendix E, the test weld shall be made under conditions that simulate the worst case likely to be encountered during construction or operations including, where these are required by Appendix E, the use of full-length suspended pipes, line-up clamps, lowering off, support and environmental conditions. The welding preheat, heat input or burn-off rate shall be at or near the lower end of the range to be qualified. Where delay in completing some joints is anticipated, the test weld shall simulate that delay. 5.11 SUPERVISION OF THE TEST WELD The test weld shall be made under continuous supervision to ensure that all the requirements of the welding procedure specification are complied with and that the weld is free from unauthorized repairs. The supervisor shall be qualified in accordance with Clause 11.4. The test should be terminated at any stage when it becomes apparent to the supervisor that a satisfactory weld cannot be made.

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5.12 IDENTIFICATION OF THE TEST WELD Each qualified welding procedure and each welder or operator shall be uniquely identified. This identification shall be clearly marked on the test piece adjacent to the weld.

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AS 2885.2—2007

TABLE 5.4.2(A) ITEMS FOR QUALIFIED PROCEDURES Item (see Note 1)

Remarks

PIPE 1

(a)

Material specification

Pipe and components complying with the AS 2885 set of Standards, another relevant Australian Standard, or another Approved Standard

(b)

Material manufacturer

Where material grade ≥X70

(c)

Material carbon equivalent (CE)

CE = C +

Mn C r + M o + V C u + N i + + 6 5 15

2

Wall thickness

Nominal wall thickness of each component of the joint

3

Diameter group

Applicable to the diameter of each pipe, branch pipe or component

PROCESS 4

Welding process

The arc welding process (e.g., MMAW, automatic GMAW, GTAW, or a nominated combination)

DESIGN 5

Preparation

Joint preparation e.g., type and details of bevel, root face, and gap, and the dimensional tolerances upon the preparation. For high-low limits refer to Clause 15.4.3

6

Weld shape and size

Shape and size of welds

7

Backing

Type of backing or consumable insert (if used)

8

Passes

Number and sequence of passes (including stripper passes)

9

Position

Positions shown in Table 4.2(A)

10

Direction of welding

Vertical up or vertical down

FILLER 11

Filler metal

Size and classification of electrode or welding wire for each pass

SHIELDING 12

13

Shielding gas

Shielding flux

(a)

Type and composition of gas or gas mixture used for shielding or backing

(b)

Nozzle or cup size

(c)

Type and flow rate for shielding or backing gases

Type, size, classification, make, and brand of flux

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ELECTRICAL 14

Electrical characteristics

Arc type, current, polarity and voltage for each size of electrode.

PROCEDURE 15

Number of welders

Minimum number of root and hot pass welders

16

Removal of line-up clamp, and/or type of lift (see Note 4)

Minimum percentage of root pass completed before release of clamp. Where less than 100% the location of the completed proportion shall be specified (see Notes 5 and 6). The type of lift shall also be specified

17

Tack welding (if used)

Number and size of tacks employed (continued)

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TABLE 5.4.2(A) (continued) Item (see Note 1) 18

Time lapse between individual passes (see Note 2)

Remarks Maximum time lapse— (a)

between the start of the root pass and the start of the hot pass; and

(b)

between subsequent passes

19

Preheat temperature and interpass temperature

Heating method, width heated, preheat temperature and interpass temperature

20

Post-weld heat treatment and postweld cooling

(a)

For post-weld heat treatment, the heating method, width heated, minimum and maximum temperature, time at temperature, method of temperature measurement, and control of maximum and minimum cooling rates

(b)

For deliberate accelerated post weld cooling above 100°C, the method and intensity or rate of cooling

21

Heat input or burn-off rate (see Note 3)

Heat input or burn-off rate for each pass

CLEANING 22

Cleaning

Equipment and method used

DEFECT ACCEPTANCE CRITERIA 23

Visual inspection and NDE acceptance criteria

The tier of acceptance criteria for girth weld discontinuity

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NOTE: Item indicates the specification topic.

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AS 2885.2—2007

TABLE 5.4.2(B) ESSENTIAL VARIABLES FOR QUALIFIED WELDING PROCEDURES Item (see Note 1)

Essential variable

PIPE 1

2

Material

Wall thickness (see Note 5)

(a)

Change of material grade between 0.05 above that used for the procedure test weld

(d)

For actual CE values of ≥ 0.35, an increase of carbon equivalent of > 0.03 above that used for the procedure test weld (see Clause 5.6.1(b))

Tier 1: Change of material thickness in a component of a joint between 1.2 nominal thickness Tier 2 and Tier 3: Change of material thickness in joints with the same nominal thickness between 1.2 nominal thickness In tapered joints or branch welds the thickness to be considered shall be the effective thickness on the thicker side of the joint. The effective thickness shall be as defined in WTIA Technical Note 1

3

Diameter group (see Note 4)

Change in nominal outside diameter outside the diameter groups qualified as follows: (a)

D ≤60.3 mm

(b)

60.3 mm < D ≤508 mm

(c)

D >508 mm where D is the nominal diameter of the test weld

Or, as an alternative to the diameter groups given above, where there is a change in diameter from a qualified procedure of more than 50% of the nominal outside diameter PROCESS

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4

Welding process

(a)

A change from one welding process or combination to another

(b)

Change from a manual operation to semi-automatic or automatic operation, or vice versa

(c)

Change of automatic welding system used

(a)

Any change to the nominal dimensions of the weld preparation and their tolerances

(b)

An increase in the permitted level of high-low beyond the limits of Clause 15.4.3

DESIGN 5

Preparation

6

Weld shape and size

Change beyond that permitted by joint design (see Clause 10)

7

Backing

Deletion or addition or change of a backing material or consumable insert (continued)

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TABLE 5.4.2(B) (continued) Item (see Note 1)

Essential variable

8

Passes

Not limited unless it is a reduction to less than 4 passes

9

Position

Change in position other than as permitted by Table 4.2(A)

10

Direction of welding

Change between vertical up and vertical down

FILLER 11

Filler metal (electrodes, filler wire)

(a)

Any change in classification of welding consumables as specified by Table 2.2.1

(b)

Change in diameter of electrode, filler wire or rod for the root pass

(c)

For single-sided butt welds and fillet welds, any change of root pass electrode brand name

(d)

For electrodes of higher strength than E4110, a change in any of the following: (i)

The type or nominal level of alloying elements used in the weld metal

(ii)

Manufacturer and factory of origin

(iii)

A significant change in the proportion of the thickness welded with different electrode classifications

(e)

For GMAW or FCAW electrodes, a change in brand designation, factory of origin or electrode diameter

(a)

Change between one gas or mixture and another gas or mixture

(b)

Decrease in shielding gas flow rate by more than 10% or decrease in the nozzle or cup size

(c)

Change of gas backing parameters

(a)

Change in flux type, size, classification

(b)

Change in combination of flux and electrode, which results in a different classification number

(a)

Change of polarity of the electrode

(b)

Change of electrical current between a.c. and d.c.

(c)

Change of arc type between spray arc, globular arc, pulsed arc, and short-circuiting (dip transfer) arc or between the use of a conventional power source and a controlled waveform power source.

(d)

Change of more than 10% in contact tube-to-work distance

(e)

Change of current and/or voltage to a value outside the manufacturer’s published recommended range or, when working outside the manufacturer’s recommended range, the qualified range of values of current and/or voltage

SHIELDING 12

13

Shielding gas

Shielding flux

ELECTRICAL

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14

Electrical characteristics

PROCEDURE 15

Number of welders

Decrease in number of welders used on any root pass, or hot pass, in the procedure test weld (continued)

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AS 2885.2—2007

TABLE 5.4.2(B) (continued) 16

Removal of line-up clamp (if used) and/or a change in the type of lift

(a)

A reduction in the proportion of root pass welded before the line-up clamp is released

(b)

A change from normal to extreme lift (see Appendix E)

17

Tack welding (if used)

A reduction in the number or size of tack welds or both

18

Time lapse between individual passes (see Note 2 and Clause 5.10)

Increase in time lapse beyond the qualified range

19

Preheat temperature and interpass temperature

(a)

For material grades of less than X70 a decrease in material temperature of more than 25°C below or an increase of more than 75°C above that used in the procedure test weld

(b)

For material grades of X70 or higher a decrease in material temperature of more than 10°C below or an increase of more than 75°C above that used in the procedure test weld

Note: Refer to Clause 5.9 which requires the test weld to be made under conditions that simulate the worst case to be encountered in production. 20

21

22

Post-weld heat treatment and postweld cooling

Heat input or burn-off rate (see Note 3)

Cleaning

(a)

Change in post-weld heat treatment

(b)

Change in post-weld cooling method and intensity, or rate of cooling (see Clause 3.2)

(a)

For mechanized or automatic welding, a change of heat input of more than 15% of the nominated average used in the procedure test weld

(b)

For manual metal-arc welding a reduction of heat input or burn-off rate on the root pass of more than 10%, or on the other passes a change of more than 20%

Equipment and method used

DEFECT ACCEPTANCE CRITERIA Visual examination and NDE acceptance criteria

An increase in the Tier number

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23

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NOTES TO TABLE 5.4.2(B) The essential variable specifies the limits outside which re-qualification is required. Changes in nonessential variables require documentation but do not require re-qualification. Non-essential variables are those Items in Table 5.4.2(A) which are not listed as essential variables in Table 5.4.2(B).

2

The method of defining time lapse shall be the same for production welds as is used for procedure qualification welds. It is recommended that the time lapse from start of root pass to start of hot pass be the defined method to avoid uncertainties associated with root repairs.

3

Burn-off rate is defined as the ratio of length of electrode consumed to the length of weld pass deposited. WTIA Technical Note 1 provides information relating burn-off rate to heat input.

4

The essential variables in Table 5.4.2(B) primarily address the risk of HACC. This is clearly evident by the latitude extended to the range of thickness (Item 2). Tier 2, however, permits increased defect limits based on demonstrated mechanical properties, i.e., weld metal strength matching and fracture toughness. Although Tier 2 defect limits are proportional to wall thickness, variations in wall thickness can strongly influence defect tolerance. This is principally a consequence of the fact that planar defects are assumed to be one weld pass deep (i.e., 3 mm). Such an assumed defect depth in thin-walled pipe can significantly change the requirement of weld strength matching (despite the proportional decrease in defect limit). For this reason the Tier 2 and Tier 3 lower limit multiplier for thickness range is more restrictive than that for Tier 1.

5

Research work carried out by the CRC for welded structures (CRC-WS) has shown that for normal lifts (see Appendix F) the additional strains, over and above the weld contraction strains, caused by lifting and lowering are small for pipe diameters less than DN 500 It has also shown that providing due attention is paid to the other factors governing the risk of HACC, the removal of the line-up clamp after at least 50% of the root pass is completed, does not by itself cause cracking.

6

The proportion of the root pass that is completed before clamp release shall be ≥50%.

7

Where the proportion of the root pass that is completed before the line-up clamp is released is 13

Nominal outside diameter (D)

Tensile (Note 2)

Side bend test (Note 3)

(Clause 6.4.3)

(Clause 6.4.4)

Macro

Hardness (Note 4)

Charpy V-notch test (Note 5)

CTOD test (Note 5)

(Clause 6.4.5)

(Clause 6.4.6)

(Clause 6.4.7)

(Clause 6.4.8)

(set of 3)

(set of 3)

mm ≤ 33.4

1

—

1

1

—

—

>33.4 ≤60.3

1

1

1

1

1

—

>60.3 ≤114.3

1

2

2

2

1

—

>114.3 ≤323.9

2

2

2

2

1

—

>323.9

4

4

2

2

2

—

≤114.3

1

2

2

2

1

1

>114.3 ≤323.9

2

4

2

2

1

1

>323.9

4

4

2

2

2

1

Fillet

All

All

—

—

4

2

—

—

Branch: tee-butt and fillet

All

All

—

—

4

2

—

—

Longitudinal butt joints

All

All

2

2

2

2

—

Repair

All

All

—

—

1

1

—

—

Weld metal deposit repair (Note 6)

All

All

—

2

4

2

—

—

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NOTES: 1

Where two or more welders or operators make a weld, at least one of each test specimen type shall be taken to represent each welder’s or operator’s work.

2

Where the criteria for acceptance of girth weld discontinuities is Tier 2 (see Clause 22.3.1(c)), the weld reinforcement shall be removed.

3

Except for weld metal deposit repair welds, side bend tests are applicable only to welds made by gas metal-arc and flux cored welding processes.

4

The hardness test shall be made on the macro test specimens.

5

Applicable where the joint is not made entirely with E4110 electrodes and/or when the criteria for acceptance of girth weld discontinuities is Tier 2 or Tier 3 (see Clause 22).

6

Weld metal deposit repairs to pipelines made in accordance with Clause 13.

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41

SECT ION

7

QUA L I F I C AT I ON O PE RA T O R

AS 2885.2—2007

O F

A

WE LDER

7.1 PURPOSE OF QUALIFYING A WELDER A welder shall be qualified in order to demonstrate an ability to follow the appropriate qualified welding procedure and the dexterity to make welds using that procedure to the requirements of this Standard. 7.2 CATEGORIES AND SCOPE OF WELDER OR OPERATOR QUALIFICATION This Standard specifies three categories of qualification, as follows: (a)

Category 1 (multiple qualification) A welder holding a Category 1 (multiple qualification) may weld any type of joint and in any position, but shall be limited by the welding procedure essential variables and welder essential variables.

(b)

Category 2 (partial qualification) A welder holding a Category 2 (partial qualification) may weld only the type or types of weld (see Table 4.2(B)), the weld pass(es), and the section of the weld and in the position qualified (see Table 4.2(A)), but shall be limited by the welding procedure essential variables and the welder essential variables.

(c)

Category 3 (operator qualification) An operator holding a Category 3 (operator qualification) may weld the type or types of weld using automatic welding and in the positions qualified, but shall be limited by the welding procedure essential variables and the welders and operators essential variables.

NOTE: Automatic welding does not include semi-automatic welding, which is qualified as Category 1.

7.3 METHODS OF QUALIFICATION

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A welder or operator shall be qualified by one of the following methods: (a)

The welding of a test piece that simulates the production weld, and its subsequent examination, testing, and assessment in accordance with Clause 8.

(b)

The production of documentary evidence showing that the test piece required for the qualification of the welding procedure has been welded, and that the procedure has been qualified.

(c)

Where a welder holds a Category 2 (partial qualification) and is required to qualify for a Category 1 (multiple qualification), the successful making of the appropriate additional test welds.

(d)

Assessment of the welder or operators first production weld in accordance with Clause 8.1.

7.4 QUALIFICATION BY TESTING Where a welder or operator is to be qualified by testing, a test weld shall be made on a suitable test piece in accordance with a qualified welding procedure. The test weld shall be examined and tested. Where the weld complies with this Standard and the results have been recorded (see Clause 8.5), the welder or operator shall be qualified. Where two or more welders or operators qualify on a single test piece, each welder or operator shall be qualified for that position used and section or portion of the weld made. www.standards.org.au

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Part or all of the welder or operator qualification tests may be waived on production of evidence that similar welds, within the limits of the essential variables (Table 7.5) have been made within the previous 12 months. 7.5 ESSENTIAL VARIABLES FOR WELDERS AND OPERATOR Essential variables for welders and operators shall be as listed in Table 7.5. NOTES: Essential variables for a welder or operator are those variables in which a change outside the limits shown in Table 7.5 is considered likely to result in a change in the mechanical properties and soundness of a weld, e.g., a change in technique or welding process, change in welding position.

2

The essential variables associated with the welder or operator qualification and welding procedure qualification are not the same; welder or operator qualification is a function of the essential variables listed in Table 7.5.

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AS 2885.2—2007

TABLE 7.5 ESSENTIAL VARIABLES FOR QUALIFIED WELDERS AND OPERATORS Categories (see Notes) Category 1 qualification (multiple)

Category 2 qualification (partial)

Category 3 qualification (automatic welding)

A

A

A

—

A

A

—

A

—

Change of basic joint design used for the welding procedure qualification test (e.g., angle of bevel, root gap, root face)

—

A

A

Deletion of backing strip or a consumable insert in a single-sided butt weld

A

A

A

—

A

A

A

A

A

A

A

A

A

A

A

Item

1

Welding process Change of welding process or combination of welding processes

2

Material—Thickness Change of material thickness (δ N ) beyond the range δ N/2 to 1.5δ N, where δ N equals the thickness used in the welding procedure qualification test weld

3

Material—Outside diameter Change of outside diameter beyond the range qualified in the welding procedure qualification test weld

4

5

Joint design

Welding position Addition of welding positions not qualified by the welder qualification test weld

6

Direction of welding Change of direction of welding between vertical-down and vertical-up

7

Filler metal Change of flux type from one flux type to another (e.g., cellulose to basic)

8

Electrical characteristics Change between spray arc, globular arc, pulsed arc, and short-circuiting arc (dip transfer)

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NOTES: 1

The categories are defined in Clause 7.2.

2

‘A’ indicates applicability.

7.6 TEST PIECE The size of the test piece(s) used for a welder’s qualification shall be sufficient to provide the required number of test specimens. The material for the test piece(s) shall be within the limits of the welding procedure essential variables and the welder and operator essential variables. The joint preparation shall be within specified tolerances for production, and should preferably be made by the same method as that used in production.

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7.7 ASSEMBLY OF TEST PIECES A test piece shall be assembled so that the weld can be made in accordance with the qualified welding procedure and in the required position. If tack welds are used, they shall be made in accordance with the qualified welding procedure. 7.8 AUTOMATIC WELDING EQUIPMENT Where an operator is to be tested on automatic welding equipment, the equipment shall be identical to that used in production, and it shall have been demonstrated that the equipment can make an acceptable welding procedure test weld. The operator shall be adequately trained on the automatic welding equipment before making the test weld. 7.9 CATEGORIES OF TEST WELDS 7.9.1 General The type and number of test welds shall be appropriate to the category of qualification required. 7.9.2 Test welds for Category 1 (multiple qualification) The welder shall make a butt weld and a branch weld as follows: (a)

(b)

Butt weld The welder shall make a butt weld, without a backing ring, on pipe in either— (i)

the 5G position; or

(ii)

the 6G position.

Branch weld The welder shall mark out, cut, fit, and weld a reinforced bevelled end sit-on branch to a pipe run. The outside diameter of the branch pipe shall be not less than one-third of the outside diameter of the pipe run. The branch weld shall be made with— (i)

the pipe run in either the 5G position or the 6G position;

(ii)

the branch in the 5B position; and

(iii) the angle between the axis of the pipe run and the branch at 90°. 7.9.3 Test welds for Category 2 (partial qualification) The welder shall make one or more of the types of welds classified in Table 4.2(B).

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Where the welder does not mark out, cut, and fit a branch but only welds the joint, the welder’s record shall be marked ‘WELDING ONLY ’. 7.9.4 Test welds for Category 3 (operator qualification) An operator shall make a butt weld using automatic welding equipment. 7.10 MAKING A TEST WELD The test weld shall be made in accordance with the qualified welding procedure. 7.11 SUPERVISION OF A TEST WELD A test weld for a welder or operator qualification test shall be made under continuous supervision, to ensure that the requirements of the welding procedure specification are followed and that the weld is free from unauthorized repairs.

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AS 2885.2—2007

The test should be terminated at any stage when it becomes apparent to the person supervising the test that the welder or operator does not have the ability required to produce a satisfactory weld. 7.12 IDENTIFICATION OF A TEST WELD

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The identification of the qualified welding procedure specification and each welder or operator’s identification shall be clearly marked on the test weld. The top (or other appropriate orientation) shall also be marked on the test weld along with the limits of each welder’s or operator’s work in circumstances where more than one welder or operator is involved.

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SE C T I O N 8 FOR WE LDE R

46

A S S E SSM EN T O F T E ST W E L D S OR OPERATOR QUA L I F I CAT I ON

8.1 METHOD OF ASSESSMENT A test weld made for welder or operator qualification shall be assessed by each of the following methods: (a)

Visual examination.

(b)

Where production welds are to be subject to non-destructive examination, assessment by non-destructive examination (using the methods to be used for the assessment of production welds). NOTE: Destructive tests may be used to supplement non-destructive examination.

(c)

Where production welds are not subject to examination, or assessment by either nondestructive examination or macro-examination in accordance with Clause 6.4.5.

(d)

Where more than one welder or operator is involved in making a test weld, assessment by each of the applicable methods.

8.2 VISUAL EXAMINATION The external surface and, where practicable, the internal surface of the test weld shall be visually examined in accordance with Clause 15. The visual examination shall include measurement of the height of weld reinforcement in order to ensure compliance with the requirements of Figure 15.4.2 where applicable. NOTE: Experience has shown that excessive weld reinforcement height particularly at the top and bottom of welds has been a problem in the field, which has caused serious difficulties in meeting the density requirements in radiographic inspection. For this reason it is important that an assessment be made of the capability of the welder to produce welds within the required reinforcement limits.

8.3 NON-DESTRUCTIVE EXAMINATION Where production welds are to be subjected to non-destructive examination, the test weld shall be subjected to non-destructive examination in accordance with Clause 16. 8.4 REPEATED TEST

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8.4.1 General Where the test weld fails to comply with the acceptance criteria and, in the opinion of the inspector, the welder or operator is not responsible for the failure, one further test weld may be made and subjected to the same examination. At the discretion of the inspector, a period of practice, prior to the second test, may be allowed. 8.4.2 Repeated failure If the second test weld fails to comply with the criteria of acceptance under similar circumstances, the cause shall be investigated. Where appropriate, the welding procedure should be an aspect of the investigation. 8.5 RECORD OF RESULTS A record of the results of the assessment of each test, including any repeated test, shall be made for each welder or operator qualification test.

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AS 2885.2—2007

Where tests have demonstrated that the weld is satisfactory, a record to the effect that a weld made to the particular qualified welding procedure complies with this Standard shall be signed by the person responsible for the test, thus qualifying the welder. 8.6 CLASSIFICATION OF CATEGORIES OF WELDS In order to reduce the number of test welds required for welder or operator qualification, welds shall be classified in accordance with Table 4.2(B). 8.7 PORTABILITY OF A WELDER’S OR OPERATOR’S QUALIFICATION It is recommended that, subject to the approval of the pipeline licensee, welder or operator qualification tests undertaken by others be accepted provided these tests have been— carried out in accordance with this Standard or the appropriate previous edition of this Standard; and

(b)

fully documented.

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(a)

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S E C T I O N 9 W E L D E R O R O PE RA T O R QUA L I F I CAT I O N AND D I SQUA L I F IC A T I ON 9.1 RECIPROCITY OF A WELDER’S OR OPERATOR’S QUALIFICATION A welder who qualifies for a Category 1 (multiple qualification) shall be qualified for a Category 2 (partial qualification) within the limitations of welder essential variables, and without further testing. A welder who has qualified to make a weld having one type number shall be qualified to make welds having other type numbers in accordance with Table 4.2(B). 9.2 PERIOD OF VALIDITY A welder’s or operator’s qualification shall remain valid until withdrawn (see Clause 9.4) provided, during the preceding 12 months, the welder or operator has been engaged in welding to the same qualified welding procedure, or a procedure that is within the essential variables for qualified welders and operators in Table 7.5. 9.3 QUALIFICATION RECORD A record shall be made of the tests undertaken by each welder or operator and of the detailed results of each test. A list of qualified welders or operators, including the identification symbol or mark, and the qualified welding procedures for which each is qualified shall be signed by the inspector and maintained by the pipeline licensee. 9.4 DISQUALIFICATION OF A WELDER’S OR OPERATOR’S QUALIFICATION Where production welds made by a specific welder or operator frequently fail to comply with the criteria of acceptance, thus demonstrating that the welder or operator no longer has either the ability to follow the qualified welding procedure or the dexterity to make a satisfactory weld, the welder’s qualification shall be withdrawn.

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The welder or operator shall be requalified again before making further production welds or repairs to welds.

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SECT I O N

1 0

D E S IG N

AS 2885.2—2007

O F

A

W E L D E D

J O I N T

10.1 GENERAL A welded joint shall be designed to be capable of withstanding the design forces, and strains presented by AS 2885.1 and, for pressure-containing components, shall be leak-tight in accordance with AS/NZS 2885.5. Details of the weld preparations shall be in accordance with those shown in the qualified welding procedure specification. The welding procedure specification shall include tolerances for all of the specified dimensions. 10.2 BUTT WELDS BETWEEN COMPONENTS OF EQUAL NOMINAL WALL THICKNESS The weld preparation for a butt weld between components of equal nominal wall thickness shall be single V type, double V type, or an approved preparation. For a manual metal-arc welding process, joints using the combination of weld preparations shown in Figure 10.2 are preferred. For other welding processes, the weld preparation shall have been shown to be satisfactory by being qualified in the welding procedure test. 10.3 BUTT WELDS BETWEEN COMPONENTS OF UNEQUAL NOMINAL WALL THICKNESS The weld preparations on a butt weld between components of unequal nominal wall thickness shall be as shown in Figure 10.3. When the specified minimum yield strengths of the components to be jointed are unequal, the deposited weld metal shall have tensile strength at least equal to that of the thinner component as demonstrated by carrying out a transverse butt tensile strength test in accordance with Clause 6.4.3. This may be demonstrated by a joint using the thinner material only. In the case of the thicker component, the thickness for design internal pressure shall be not greater than 1.5 times the nominal thickness of the thinner component. 10.4 REINFORCEMENT OF A BUTT WELD

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The height of the weld reinforcement of a butt weld shall comply with Clause 15.4.2, and with any requirements specified in the engineering design. Unless otherwise specified in the design, this Standard does not specify minimum levels of weld reinforcement beyond filling the joint flush with the parent metal. 10.5 FILLET WELD 10.5.1 Dimensions of a fillet weld A fillet weld may be slightly convex or slightly concave and shall have the specified leg length or throat thickness. The size of fillet weld shall be the leg length of the largest isosceles triangle that can be inscribed in the weld section. The size, convexity or concavity and leg lengths shall be measured to the nearest 0.5 mm on a section scribed with lines as shown in Figure 10.5. The depth of the concavity or the height of the convexity shall be equal to or less than 2 mm.

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10.5.2 Fillet welding a lug, boss or pad A fillet-welded lug, boss, or pad shall comply with the following: (a)

Dimensions The length of a lug shall be not less than 50 mm. A boss should be circular with a diameter not less than 50 mm. Rectangular or square pads may be used, provided the corners of the pad are rounded.

(b)

Lugs The long sides of a rectangular lug shall be in the circumferential direction of the pipe.

(c)

Surface preparation The area of the pipe to which the connection is to be made shall be clean and be free from oil, scale, and surface-connected defects.

(d)

Fitting The attachment shall be shaped to the circumference of the pipe or pressurecontaining component.

10.5.3 Miscellaneous fillet welds The size of fillet welds for flanges, sleeve and forged socket fittings shall be as specified in AS 4041. 10.6 WELDING OF THREADED JOINTS Welding shall not be carried out on threaded joints for any purpose, including sealing against leakage. 10.7 REINFORCEMENT OF A WELDED BRANCH CONNECTION The reinforcement of a welded branch connection shall be determined from AS 2885.1. 10.8 REINFORCEMENT OF MULTIPLE OPENINGS The reinforcement of multiple openings shall be determined from AS 2885.1. 10.9 FORGED BRANCH FITTING A forged branch fitting with integral reinforcement shall be designated sit-on or set-in. The weld between a set-in branch fitting and a pipe shall be designated a tee-butt weld. The weld between a sit-on branch fitting and a pipe shall be designated a single bevel butt weld. The welding of forged branch type fittings with integral reinforcement, such as Weldolets, is shown in AS 4041. The weld joint design shall be in accordance with the AS 2885.1.

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10.10 FABRICATED ELBOW OR BEND The pressure-containing welds in a fabricated elbow or bend shall be full penetration butt welds. 10.11 EFFECT OF COMPONENTS UPON PIG PASSAGE The method of welding components into pipelines, which may require pigging during their design life, shall— (a)

allow free passage of pigs in the main pipeline; and

(b)

prevent entry of main pipeline pigs into the branch line.

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10.12 OFFSET OF LONGITUDINAL WELDS Longitudinal welds on the opposite sides of a girth weld shall be staggered. The minimum offset distance between such welds shall be not less than six times the pipe wall nominal thickness. 10.13 DISTANCE BETWEEN WELDS

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A weld for a welded branch pipe or a weld for an attachment to the pipe should not be located within a distance of approximately 6 times the pipe wall nominal thickness from a longitudinal weld, spiral weld, or circumferential weld in the pipe.

NOTE: The standard root face dimension is 1.6 ±0.8 mm. DIMENSIONS IN MILLIMETRES

FIGURE 10.2 END PREPARATIONS AND ACCEPTABLE COMBINATIONS OF END PREPARATIONS

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NOTE: The standard root face dimension is 1.6 ±0.8 mm.

FIGURE 10.3 WELD PREPARATIONS FOR BUTT WELDS USING MMAW—UNEQUAL NOMINAL WALL THICKNESS

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FIGURE 10.5 CROSS-SECTION OF A FILLET WELD

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SECT ION

11

PRODUCT I ON

WE LDS

11.1 WELDING PROCESS Production welds shall be made in accordance with previously defined and qualified procedures of Clause 5.3(a), (b), (c) or (d), and within the limits of essential variables. NOTE: It is recommended that gas tungsten arc welding or gas welding be used for butt welds on pipe of outside diameter 42.2 mm and less.

11.2 WELDING EQUIPMENT Welding equipment shall be of a size and type suitable for the work. It shall be maintained in a condition that will ensure the production of satisfactory welds, the continuity of operation and the safety of personnel. 11.3 WELDER AND WELDING PROCEDURE All welds shall be made by qualified welders or operators using a qualified welding procedure. 11.4 SUPERVISION OF WELDING Welding shall be carried out under the supervision of an approved person who has had appropriate experience and training in the supervision of welding of pipelines and the use of ancillary equipment. NOTE: AS 1796 provides rules for certification of welding supervisors.

11.5 SAFETY IN WELDING 11.5.1 General All welding operations shall comply with the Australian Standards relevant to safety in welding. 11.5.2 Welding site A thorough check shall be made in and around the welding site to ensure there are no substances that could constitute a risk of fire or explosion.

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11.6 STORAGE AND HANDLING OF ELECTRODES, FILLER RODS AND FLUXES Electrodes, filler rods and fluxes shall be stored and handled in accordance with Clause 2.2.3, in such a manner that will prevent damage or deterioration. Consumables in opened containers shall be protected from deterioration. Damaged material shall not be used. 11.7 WELDING IN ADVERSE CLIMATE CONDITIONS Welding shall not be carried out under climatic conditions that contribute to persistent defects. Where a gas-shielded arc-welding process is used and winds or draughts could impair the quality of the weld, welding habitats or windshields should be used.

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11.8 PREPARATION FOR WELDING 11.8.1 Edge preparation Surfaces and edges to be welded shall be smooth, uniform and free from cracks, fins, tears, and other defects that could affect the soundness of the weld. Surfaces to be welded and surfaces adjacent to the weld shall be free from paint, scale, slag, moisture, rust, grease, or other foreign matter. 11.8.2 Internal cleaning The internal surface of the pipe shall be free of loose debris. It should be swabbed if necessary. 11.9 METHOD OF MAKING THE WELD PREPARATION The weld preparation shall be made in the manner specified in the qualified welding procedure specification. 11.10 ACCURACY OF ALIGNMENT Components shall be assembled to provide alignment within the limits of Clause 15.4.3. 11.11 LINE-UP CLAMP Line-up clamps shall have the following attributes: (a)

Provide rounding of pipe ends (removal of ovaling does not expand pipe diameters).

(b)

Accommodate dimensional tolerances in abutting pipes.

(c)

Provide even distribution of ‘high-low’.

(d)

Have appropriate gap setting.

(e)

Provide access for welding operation.

(f)

They shall not damage pipe coating (both internal and external)

(g)

They shall not contaminate the weld (pick up impurities).

NOTE: Line-up clamps require specific settings and maintenance.

The line-up clamp shall be released only after the length of root pass is equal to or greater than that specified in the qualified welding procedure specification.

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11.12 TACK WELDS Tack welds shall only be used as a means of alignment during welding when tack welding is specified in the qualified welding procedure. Tack welds shall be deposited only in the weld groove and, where the tack weld is to be incorporated into the finished weld, full fusion at the root shall be obtained. The length of individual tack welds shall not be less than 25 mm or 20% of the outside diameter of the pipe, whichever is the lesser. Tack welds that are unsound shall be ground out. 11.13 WORKING CLEARANCE There shall be safe access and clearance for welding. 11.14 PLACEMENT OF WELD PASSES Consecutive or adjacent weld passes shall not be started at the same circumferential position.

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11.15 ARC STRIKE AND ARC BURN An arc shall be struck only on the fusion faces or the surfaces of the parent material that will be fused into the weld. An arc burn that results from an inadvertent arc strike shall be removed in accordance with Clause 24 or 25. The work return clamp shall make good electrical contact with no evidence of arcing. 11.16 CLEANING Each pass of weld metal shall be cleaned in the manner specified in the qualified welding procedure. 11.17 PEENING Peening shall not be carried out on the root pass or the capping pass or passes. On filler passes, peening shall be carried out when specified in the qualified welding procedure. 11.18 INSERT PATCHING Insert patching shall not be carried out. 11.19 PREHEAT AND INTERPASS TEMPERATURE 11.19.1 General The preheat and interpass temperature shall be that specified in the qualified welding procedure. Both parts of the parent metal shall be at the required temperature at the time that welding is commenced. 11.19.2 Application of preheat and interpass temperature The specified preheat and interpass temperatures shall be maintained during all stages of welding including tack welding. 11.19.3 Extent of heating The full thickness of both parts of the parent metal shall be heated to the required temperature. The width of the heated band on either side of the centre-line of the weld shall be not less than 75 mm or three times the width of the weld, whichever is the greater. 11.19.4 Monitoring of preheat and interpass temperature The temperature shall be monitored at positions that are not less than 25 mm from the weld position by the use of temperature-indicating crayons or paint, thermocouples, pyrometers, or other appropriate methods.

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11.19.5 Condensation Where preheating is specified in the qualified welding procedure, and where a gas flame is used for preheating, no condensation or moisture shall remain. Where the metal temperature is less than 100°C, the flame should not be directed into the weld preparation. 11.20 POST-WELD HEAT TREATMENT Where specified in the qualified welding procedure, post-weld heat treatment shall be carried out. 11.21 IDENTIFICATION OF A PRODUCTION WELD A production weld shall be identified in an approved manner.

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SECT ION 12 WE LD I N G AND CUTT I N G ON A P IPE L I NE A F T E R C O M M I SS IO N I N G O R A FT E R HYDR O ST A T I C T E ST I N G 12.1 GENERAL This Section specifies the requirements for welding or cutting in special situations on a pipeline after commissioning or hydrostatic testing (for example, a pipeline repair where gas is escaping) where the pipeline will not be subjected to another pressure test before it is returned to service. All welding procedures and welding operations shall be qualified, documented and approved under conditions that simulate those that are expected during field welding. Pipeline repair welding shall be continuously supervised. NOTE: Guidance on methods for the repair of pipelines is given in WTIA Technical Note 20.

12.2 SAFETY All of the activities associated with welding or cutting on pipelines containing flammable and/on pressurized substances involve a high risk. The procedures that are qualified in accordance with Clause 12.1 shall include a thorough risk assessment in accordance with AS 2885.1. The risk assessment shall include the safety of personnel and suitability of equipment. These safe working procedures shall be approved. Specific attention should be paid to the risk of ignition or electrocution due to the pipeline being at an elevated potential with respect to earth, and the likelihood that it may carry substantial currents. Bonding cables should be installed prior to cutting, to effectively bypass any current that may be flowing in the pipeline especially if the methods of cutting employed are not expected to cause ignition. The pipeline shall be earthed prior to the commencement of welding or cutting. Because of the potentially hazardous nature of the earthing procedure, the earthing procedure shall be approved. The formation of mixtures of flammable vapour, including gas and air, shall be prevented. 12.3 HOT REPAIR OF LEAKING GAS-FILLED PIPELINES

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Hot repair of leaking gas-filled pipelines shall only be permitted when all of the following conditions prevail: (a)

The pipeline contents are known to be natural gas as defined in AS 4564.

(b)

A slight flow of gas is kept moving toward the point where thermal cutting or welding is being done.

(c)

The gas pressure is controlled to a slight positive pressure of approximately 150 Pa gauge.

(d)

All slots or open ends are sealed with tape, tightly fitted canvas or both, or other suitable means, as soon as they are made so as to maintain positive pressure and prevent the formation of an explosive air/gas mixture.

(e)

Two openings are not uncovered at the same time. NOTE: This is particularly important where the two openings are at different elevations.

(f)

Any escape of gas is ignited and kept burning.

(g)

Where the gas is toxic, adequate precautions are taken to protect all personnel including the public.

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In addition to the requirements of Clauses 12.1 and 12.2, the hot repair procedures shall include approved procedures for the following: (i)

The detection of explosive mixtures.

(ii)

The means of maintaining work site to mainline valve communication.

(iii) The method of regulating gas pressure. 12.4 WHERE GAS IS NOT ESCAPING Where work is to be carried out on a pipeline containing gas, but where gas is not escaping, the requirements of Clause 13 shall apply. 12.5 PIPELINES CONTAINING PETROLEUM FLUIDS OTHER THAN LEAN NATURAL GAS Welding shall only be carried out on a pipeline containing petroleum fluids other than lean natural gas (see AS 2885.1) when no fluid is allowed to escape from the pipeline. A pipeline that contains, or has contained, petroleum fluids other than lean natural gas but has not been purged shall be cut only by mechanical means. Care shall be taken to prevent ignition due to electrical sparking (see Clause 12.2). Where a pipeline is filled with air and connected to a source of petroleum fluids other than lean natural gas that cannot be completely isolated, the following procedure should be adopted during welding, thermal cutting, or repair operations: (a)

Purge the pipeline.

(b)

Ensure that— (i)

combustible hydrocarbon fluid cannot flow towards the work site; and

(ii)

valves that isolate the work from the source of hydrocarbon fluids do not leak. NOTE: It may be necessary to install stopples or spheres on each side of the work site.

(c)

Frequently test the atmosphere at the work site to ensure that an unsafe accumulation of hydrocarbon fluid does not occur as work progresses.

12.6 QUALIFICATION OF WELDER(S) The welder(s) shall be qualified for the welding position, the welding process, and the configuration of the joint.

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12.7 QUALIFICATION OF SUPERVISORS AND INSPECTORS The supervisor and inspector shall be qualified by experience and training in the welding or cutting of pipelines containing or having contained hydrocarbons, and in accordance with Clause 14.2. 12.8 FIT-UP BEFORE WELDING AND CUTTING Weld preparations shall be made accurately, and shall be in accordance with the qualified welding procedure. 12.9 EXAMINATION AND TESTING The finalized weld and adjacent material shall be subjected to appropriate 100% nondestructive examination.

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12.10 CRITERIA OF ACCEPTANCE

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Welds shall comply with the visual inspection and non-destructive examination acceptance criteria of this Standard.

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60

13 WE LD I N G ONTO S E R V ICE P I PE L I N E

AN

I N -

13.1 GENERAL—PIPELINE CONTAINING FLAMMABLE OR PRESSURIZED FLUID Where a pipeline contains stationary or flowing flammable fluid, or the internal pressure is greater than 50 kPa gauge, welding shall comply with the requirements of Clauses 13.2 to 13.15. NOTES: 1

Examples of in-service welding include fully welded repair sleeves, hot tap fittings, branch connections and weld metal deposition repairs.

2

Guidance on methods for repair of pipelines is given in WTIA Technical Note 20.

3

At times there may be a need for control of the operating pressure and flow rates in order to provide suitable conditions for welding.

4

Welding onto pipelines that contain multiphase fluids requires special consideration.

5

Welding onto pipelines with a wall thickness less than 4.8 mm requires special consideration. Research by CRC-WS has shown that the variability in heat input with MMAW for wall thickness less than 4.8 mm revealed a significant high risk of burn-through.

13.2 PRECAUTIONS TO BE UNDERTAKEN BEFORE IN-SERVICE WELDING 13.2.1 Avoidance of hydrogen-assisted cold cracking (HACC) and burn through The selection of heat input and preheat for welding on pipe with flowing hydrocarbons is a compromise between two opposing possibilities. At high heat input, the drop in the yield stress of the steel pipe at elevated temperature may lead to localized blow-out or generalized bulging. Pressure reduction may be necessary. At low heat input, the heat sink effect from the flowing fluid and the usually thick enclosing sleeve may promote hydrogen cold cracking, and preheat is usually necessary. The heat sink effect makes the achievement of effective preheat difficult. 13.2.2 Risk assessment and risk management plan Prior to the commencement of any work, a risk assessment shall be undertaken to examine all of the potential threats to the public, operating personnel, and the continuity of supply that will arise during or as a result of the in-service welding, and a risk management plan shall be developed and approved to mitigate the risks. 13.3 LINING Accessed by GHD PTY LTD on 05 Aug 2009

The effect of welding upon internal linings shall be considered. 13.4 SAFETY Detailed safety procedures shall be established and approved before work begins. 13.5 INSPECTION BEFORE WELDING The location of pipe to be welded shall be defined and the specification of the pipe shall be established. The pipe in the region of the welding shall be free of all coating material that is deleterious to the weld, or which could interfere with the inspection of the pipe. The pipe to be welded shall be inspected visually and by non-destructive means, and at least the following shall be reported: (a)

Actual wall thickness.

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(b)

Diameter, and ovality.

(c)

Any external or internal corrosion.

(d)

Any laminations or inclusions in the vicinity of the area to be welded.

(e)

Any unsoundness of a longitudinal weld or spiral weld in the vicinity of the area to be welded.

(f)

Remaining wall thickness in the corrosion pit areas for weld metal deposition repairs.

13.6 ULTRASONIC EXAMINATION BEFORE WELDING 13.6.1 Purpose of examination The purpose of the examination is to determine and record the integrity of the pipe wall in the area that is to be affected by the welding operation. 13.6.2 Method The method of examination and the reference sensitivity shall be as specified in AS 1710, for wall thicknesses greater than 5.0 mm. Where the wall thickness is between 3.2mm and 5.0mm, a 5–10 MHz twin crystal probe shall be used. 13.6.3 Criteria of acceptance The following applies: (a)

Welding shall only be carried out where the pipe is demonstrated to be free of significant laminations, inclusions, or unsoundness of any longitudinal seam or spiral seam.

(b)

The results of the ultrasonic examination shall be the subject of an engineering assessment prior to any welding being undertaken.

13.7 WELDING CONSUMABLES Welds shall be made with a hydrogen-controlled process. 13.8 HEAT INPUT The heat input (arc energy) and size of electrode shall be approved.

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13.9 QUALIFICATION OF WELDING PROCEDURES Welds shall be made in accordance with a documented, qualified and approved welding procedure developed in accordance with Clause 5, which takes into account pressure and cooling effects from the flow of fluid in the pipeline upon which welding is to be conducted, and which simulates site conditions. The essential variables in Table 5.4.1(B) only apply to welds that are not directly affected by product pressure and cooling effects such as the longitudinal seams on line stop fittings or sleeves. These joints shall be fitted with a low carbon steel back-up strip or suitable tape to prevent penetration of the weld into the carrier pipe.

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All welding that is affected by product pressure and cooling effects such as circumferential fillet welds, weld metal deposition and branch welds shall be qualified by simulated testing (see Note 1). No essential variables apply to these welds; however, grouping of certain conditions may be permitted when approved. The grouping of conditions shall involve sound engineering judgement and be fully investigated and documented with respect to burn-through and hydrogen cracking potential and should include worst case welding procedure qualification testing. NOTES: 1

Figure 13.9 describes the suggested procedure qualification test assembly.

2

Thermal analysis tools are available from Battelle, PRC-I and the CRC for Welded Structures.

13.10 WELDING SEQUENCE The recommended welding sequences are shown in Figure 13.10. Backstep welding technique for the longitudinal joints should be considered to minimize weld shrinkage effects in the case of thin wall carrier pipe.

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FIGURE 13.9 SUGGESTED IN-SERVICE WELDING TEST ASSEMBLY

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FIGURE 13.10 RECOMMENDED WELDING SEQUENCES www.standards.org.au

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13.11 QUALIFICATION OF WELDER(S) The welder(s) shall be qualified for the welding position, the welding process, and the configuration of the joint. For heat input control procedures, the welder shall be able to demonstrate the ability to maintain a heat input level within the range specified. For temper bead procedures, the welder shall be able to demonstrate proper bead placement. 13.12 QUALIFICATION OF SUPERVISORS AND INSPECTORS The supervisor and inspector shall be qualified by experience and training specifically related to in-service welding on pipeline and in accordance with Clause 14.2. 13.13 FIT-UP BEFORE WELDING Weld preparations shall be made accurately, and shall be in accordance with the qualified welding procedure. All components shall fit the pipe, and care shall be exercised to ensure that any longitudinal weld preparations are suitably aligned. Buttering passes may be required on the carrier pipe or fitting to accommodate gaps above those specified in the welding procedure. NOTE: Consideration should be given to suitable means of preventing compression of the pipe due to the contraction of the longitudinal welds on the fitting.

13.14 EXAMINATION OF TESTING The finalized weld and adjacent material shall be subjected to the appropriate 100% nondestructive examination, including tests for the presence of lamellar tearing. Before cutting the line pipe with a hot tapping tool, the weld and adjacent material should be leak-tested at a pressure not greater than the current internal pressure of the pipeline. Delayed cracking due to residual hydrogen in the weld metal may occur. Final nondestructive examination shall be carried out not sooner than 24 h after completion of welding, followed by leak testing. 13.15 CRITERIA OF ACCEPTANCE The criteria of acceptance for all in-service welding shall be as specified in Tier 1 Criteria as specified in Clause 22.1.9. 13.16 WELDING OF TEST ASSEMBLY

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For in-service welding, pipeline operating conditions that affect the ability of the flowing contents to remove heat from the pipe wall shall be simulated while test joints are being made. NOTE: Filling the test section with water and allowing water to flow through the test section while the test joint is being made has been shown to produce thermal conditions equivalent to or more severe than any typical in-service welding application (see Figure 13.9). Other media (e.g., water mist or motor oil) may be used to simulate less severe thermal conditions.

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14 ASSESSMENT OF PROD UCT I ON WE LDS AND REPA IR WE L DS

14.1 GENERAL Production welds shall be examined and assessed in accordance with this Clause 14. 14.2 QUALIFICATION OF PERSONNEL Personnel involved in the inspection of welds, or in the interpretation of results of testing, shall have qualifications or experience appropriate to the task, and shall be approved. 14.3 RESPONSIBILITIES The responsibilities of inspectors shall include the following: (a)

The witnessing of all welding procedure qualification test welds and their examination and testing.

(b)

The witnessing of all welder or operator qualification test welds and their examination and testing.

(c)

The examination of all production welds.

(d)

Ensuring that all reports and records are made as required.

14.4 METHODS OF EXAMINATION Production welds shall be subjected to the following: Visual examination in accordance with Clause 15.

(b)

Non-destructive examination in accordance with Clause 16.

(c)

For pipelines longer than 10 km, welding procedure qualification testing of a minimum of three production cut-out welds for weld procedure verification. These shall be taken at random, preferably at the end of a pipe string for least impact on production. The welds shall be chosen to verify the applicability of the welding procedure at the extremes of the envelope encompassed by the qualified welding procedure. Typically, this would involve choosing welds with low heat input (maximum welding speed) and/or low ambient temperature and/or high restraint.

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(a)

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SECT ION

15

V ISU A L

E XAM I NAT I O N

15.1 PURPOSE The weld shall be examined visually to determine that the surfaces of the weld are free from unacceptable discontinuities and the weld is dimensionally correct including that the height of weld reinforcement is within the limits necessary to achieve effective radiography as shown in Figure 15.4.2. 15.2 METHOD OF EXAMINATION Visual examination shall be undertaken without magnification other than normal prescription spectacles. Appropriate measuring tools and gauges may be used. 15.3 EXTENT OF VISUAL EXAMINATION The full length of each weld shall be examined. 15.4 CRITERIA OF ACCEPTANCE 15.4.1 All welds Welds shall not contain any visible discontinuities that exceed those specified in Clause 22. The dimensions of the weld shall comply with those shown in the welding procedure specification. 15.4.2 Butt welds The weld preparation shall be completely filled. In order to permit effective radiography of those welds that are to be radiographed, the height of external weld reinforcement shall be not greater than that specified in Figure 15.4.2. Welds that are to be radiographed, which do not comply with the weld reinforcement limits, shall be ground in order to achieve compliance. 15.4.3 Alignment (high-low) The alignment of pipe ends shall minimize the offset between abutting surfaces. For pipe ends of the same nominal thickness, the offset shall not exceed 3 mm for pipe with wall thicknesses greater than 6.4 mm, and 2 mm for pipe with wall thicknesses equal to or less than 6.4 mm. Larger variations are permissible provided the welding procedure is requalified with a higher limit of high-low.

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15.5 UNDERCUT DEPTH MEASUREMENT Undercut depth measurement shall consist of the following: (a)

External undercut The only permitted method for measuring and sentencing external undercut shall be visual or mechanical measurements.

(b)

Internal undercut The primary means of measuring internal undercut depth shall be visual or mechanical measurements. Where direct measurement is not possible, undercut comparator shims or reference radiographs in accordance with Clause 17.5 may be used. If a disagreement occurs between the visual/mechanical methods and the other methods, the former shall take precedence.

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FIGURE 15.4.2 MAXIMUM HEIGHT OF EXTERNAL WELD REINFORCEMENT IN BUTT WELDS THAT ARE TO BE RADIOGRAPHED IN ORDER TO ACHIEVE EFFECTIVE RADIOGRAPHY

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SECT ION

16 NON-DEST RUCT IVE EXAM I NAT I ON

16.1 PURPOSE The methods of non-destructive examination, the equipment, and the examining personnel shall be collectively capable of producing indications of discontinuities in welds, which can be interpreted and evaluated in order to determine whether the criteria of acceptance have or have not been attained. Discontinuities shall be evaluated in accordance with Clause 22. 16.2 ORGANIZATIONS UNDERTAKING NON-DESTRUCTIVE EXAMINATION Organizations undertaking non-destructive examination shall comply with the requirements of AS ISO/IEC 17025. 16.3 QUALIFICATIONS OF PERSONNEL Non-destructive examination personnel engaged in the supervision or interpretation of results shall be qualified in accordance with AS 3998 or equivalent. 16.4 METHODS Non-destructive examinations shall be made in accordance with a qualified procedure using one of the following methods, unless an exemption applies (see Clause 16.6): (a)

Radiographic examination.

(b)

Ultrasonic examination. NOTE: The preferred method of ultrasonic examination is with a mechanized system in accordance with Clause 19.2.

Welds made by GMAW welding should be examined with mechanized ultrasonic testing. These examinations may be supplemented with one or both of the following non-destructive tests: (i)

Magnetic particle testing.

(ii)

Penetrant testing.

16.5 AMOUNT OF NON-DESTRUCTIVE EXAMINATION Accessed by GHD PTY LTD on 05 Aug 2009

16.5.1 General The determination of the amount and the specified location of NDE shall be considered as part of the process of risk assessment conducted in accordance with AS 2885.1. Where quality monitoring systems are available, the information derived from monitoring should be used to select the regions chosen for NDE. 16.5.2 Butt welds and tee-butt welds Except where otherwise approved, all butt welds and tee-butt welds in the following locations shall be subjected to non-destructive examination: (a)

A road or railway reserve.

(b)

A stream, river, reservoir, public water supply or water catchment area that could be polluted by a leak from the pipeline.

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(c)

A branch connection not subject to hydrostatic testing.

(d)

A tunnel, pipe bridge or overhead structure.

(e)

Areas subject to flooding, possible severe land movement (see AS 1170.4) or subsidence.

(f)

A depth of cover greater than 5 m.

(g)

Welds on fittings.

(h)

Welds qualified under the terms of Clause 5.4.5.

In addition to the above, non-destructive examination shall be carried out on all butt welds that are— (i)

contained in pipeline assemblies manufactured in accordance with AS 2885.1;

(ii)

part of a pipeline that will not be hydrostatically tested before being placed into operation;

(iii) any part of a telescoped pipeline to which a test pressure factor of less than 1.25 will be applied; (iv)

in reclaimed pipe used in accordance with AS 2885.1;

(v)

repaired pipeline, including a 75 mm overlap at each end of the repair; or

(vi)

so specified by the pipeline licensee.

As well as items listed above, an additional number of butt welds shall be subjected to nondestructive examination, and this number shall be dependent on the class of pipeline as follows: (A)

Class T1 location and Class T2 location .........100% of the total number of butt welds.

(B)

Class R2 location.............................................15% of the total number of butt welds.

(C)

Class R1 location.............................................10% of the total number of butt welds.

16.5.3 Welder’s or operator’s work A sample of each welder’s or operator’s work for each day shall be selected by the inspector and be non-destructively examined. Where 100% of the selected number of butt welds has been specified (see Clause 16.5.1), the full length of each weld shall be examined.

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Where the pipeline licensee exercises its option for less than 100% of all butt welds to be examined, the length of weld examined for each welder or operator shall be one of the following: (a)

The total length of each selected weld.

(b)

Partial lengths from a sufficient number of welds to ensure that the equivalent length to Item (a) above is examined.

16.6 EXEMPTION FROM RADIOGRAPHIC OR ULTRASONIC EXAMINATION Subject to the approval of the pipeline licensee, where it is not practicable to carry out a radiographic examination or an ultrasonic examination due to the weld geometry, an approved non-destructive examination by magnetic particle testing or dye-penetrant testing shall be made.

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70

Where a butt weld in pipeline assemblies is made on pipe of outside diameter of 114.3 mm or less, and the pipe is to operate at a nominal design stress not exceeding 60% SMYS and the welded joint is pressure tested prior to operation, the non-destructive examination may be magnetic particle testing or dye-penetrant testing instead of radiographic examination or ultrasonic examination. Fillet welds shall not be radiographed. At the option of the pipeline licensee, the non-destructive examination of fillet welds and socket welds may be by magnetic particle testing or dye-penetrant testing instead of ultrasonic examination. 16.7 TIMING OF NON-DESTRUCTIVE EXAMINATION The elapsed time after welding is completed at which NDE is performed will affect the likelihood of detecting HACC. The timing of NDE is not restricted by this Standard, except for— (a)

weld procedure qualification tests (see Clause 6.1); and

(b)

welds made in accordance with procedures in which the risk of HACC has not been ‘designed-out’ in accordance with Appendix C.

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Where the risk of HACC is other than ‘remote’, the NDE on production welds shall be conducted after at least 24 h have elapsed after the completion of welding.

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SECT ION

17

RAD I OGR APH IC

AS 2885.2—2007

EX AM I N AT I O N

17.1 GENERAL The radiographic examination shall comply with all of the requirements of this Standard. The procedure shall be documented and qualified, or be previously qualified and approved. Gamma-radiography shall only be used where the risk of HACC is ‘designed out’ from the welding procedure and where permitted by the Note in Table 17.4. NOTES: 1

AS 2177 should be referred to for guidance.

2

The preferred technique of radiographic examination of welds in pipelines is that of using an internal orthogonal x-ray radiographic crawler as, inter alia, the detectability of imperfections including cracks is superior to that obtained using high-energy gamma rays or double-wall exposure techniques.

17.2 SAFETY AND PROTECTION FROM IONIZING RADIATION All radiographic examination shall be carried out in accordance with statutory State and Federal health and safety regulations. 17.3 DENSITY The radiographic density through the parent metal shall be as follows: (a)

X-radiography ............................................ not less than 2.5 and not greater than 4.0.

(b)

Gamma-radiography ................................... not less than 3.0 and not greater than 4.0.

The radiographic density through the weld metal shall not be less than 1.3. Weld reinforcement shall be within the limits of Figure 15.4.2. If the density in the parent metal falls within the range specified above but the required minimum for the weld metal is not met, then the weld reinforcement shall be ground in the regions of insufficient density and the radiograph(s) shall be retaken so that the above requirements are met. 17.4 IMAGE QUALITY The image quality indicator (IQI) shall be a wire type complying with AS 2314.

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NOTE: The specification of wire type IQI in AS 2314 complies with ISO 1027 and DIN 54109.2.

Radiographic image quality is indicated by the smallest wire visible in the radiograph assessed through the parent metal. IQI wire numbers for corresponding nominal wall thicknesses shall comply with Table 17.4.

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TABLE 17.4 IMAGE QUALITY INDICATOR (IQI) SENSITIVITY vs MATERIAL THICKNESS IQI to DIN 54109/ISO 1027 Nominal wall thickness mm

IQI on film side Single wall/ single image Number

Diameter mm

Double wall/ single image Number

Diameter mm

> 3.0

≤ 4.5

15

0.125

14

0.16

> 4.5

≤ 6.2

14

0.16

13

0.20

> 6.2

≤ 8.4

14

0.16

13

0.20

> 8.4

≤ 12.0

13

0.20

12

0.25

> 12.0

≤ 15.9

12

0.25

12

0.25

> 15.9

≤ 20.0

11

0.32

11

0.32

> 20.0

≤ 32.0

10

0.40

10

0.40

> 32.0

≤ 40.0

10

0.40

10

0.40

> 40.0

≤ 50.0

9

0.50

9

0.50

NOTE: Welds in pipe Grade AP15L X60 or lower, welded entirely with low strength electrodes and in R1 locations, may be examined using gamma-radiography. Image quality indicator wire visibility using this technique may be reduced by 1 in the first three rows.

17.5 UNDERCUT DEPTH MEASUREMENT Where radiography is used as the only method of determining internal undercut (see Clause 15.5), the images of discontinuities that have been identified as undercut shall be assessed for depth by comparing the density of its film image with the density of the film images of grooves of given sizes cut into a comparator shim. Alternatively, undercut may be assessed for depth by comparing production radiographs with reference radiographs prepared from weldments of the same thickness and welding procedure, and where the depth of real examples of undercut has been measured by macro examination.

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Undercut comparator shims shall comply with the following: (a)

Material A comparator shim shall have the same radiographic opacity as the material under examination.

(b)

Dimensions The dimensions of comparator shims shall be as shown in Figure 17.5.

(c)

Location A comparator shim shall match the curvature of the pipe and shall be placed alongside and parallel with the edge of the external weld with the grooves on the inside radius. The shallowest groove on the comparator shim shall be placed closest to the weld.

(d)

Number of comparator shims Comparator shims shall be visible as follows: (i)

For panoramic exposures, a minimum of two comparator shims spaced approximately equidistant shall appear on the radiograph. The separation of comparator shims shall not exceed 400 mm.

(ii)

Where a multi-exposure method is used, comparator shims should be located adjacent to the image quality indicators or at locations where undercut is expected.

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(iii) Where a multi-exposure or multi-film method is used, at least one shim should be visible on each cut length of film of 400 mm or less. (e)

Method of assessment of undercut using comparator shims To assess the relative depth of undercut, compare the density of the actual undercut with the density observed in the machined grooves of known depth in the undercut comparator. This may be achieved by totally masking all areas of the radiograph, with the exception of a window that is of comparable size with the actual undercut, and comparing the density observed in the same size window of the machined grooves.

NOTES: 1

Tolerance on depth of groove ±0.05 mm.

2

A Charpy V-notch tool should be used to produce the grooves. DIMENSIONS IN MILLIMETRES

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FIGURE 17.5 UNDERCUT COMPARATOR SHIM

17.6 GAS PORE DEPTH MEASUREMENT The images of discontinuities that have been identified as gas pores (GP) shall be assessed for depth (through thickness dimension) by comparing the density of its film image with the density of the film images of flat bottom hole. The gas pore comparator shim shall comply with the following: (a)

Material The comparator shim shall have the same radiographic opacity as the material under examination.

(b)

Dimensions The dimensions of the comparator shim shall be as shown in Figure 17.6.

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(c)

74

Method of use Reference radiographs shall be made of the comparator shim and test weld. These reference radiographs shall be used in order to assess the depth of gas pores in production radiographs.

50

3 15

PLAN VIEW

3

0.5

1.0

2.0

3.0

END VIEW

H o l e d e pth s SIDE VIEW

T h i rd a n g l e p rote c ti o n

G a s p o re s h i m

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DIMENSIONS IN MILLIMETRES

FIGURE 17.6 GAS PORE COMPARATOR SHIM

17.7 INTEPRETATION AND ASSESSMENT OF RADIOGRAPHS Discontinuities observed on radiographs shall be identified, sized, and assessed in accordance with Clause 22. Defects shall be correlated with the radiograph, located with respect to the weld and recorded on a test report. Defects shall be identified, and symbolized in accordance with AS 4749. NOTE: Where the terminology and abbreviations used in AS 4749 do not adequately describe some of the discontinuities found in pipeline welds, additional descriptive abbreviations may be required (e.g., I = internal; E = external; HB = hollow bead; AS = arc strike; WT = wagon tracks; A = absence of defects; DIP = debris in pipe).

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17.8 CRITERIA OF ACCEPTANCE The weld shall comply with Clause 22. 17.9 REPORT OF RADIOGRAPHIC EXAMINATION A test report shall be made in accordance with AS 2177 and the requirements of this Standard. 17.10 RETENTION OF RADIOGRAPHS

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Radiographs shall be retained for a minimum of three years.

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SECT ION 18 QUA L I F Y I NG A R AD I O G R A PH I C PRO CE D U RE 18.1 RADIOGRPHIC PROCEDURE A radiographic procedure shall be developed and documented in accordance with AS 2177 and the requirements of this Standard. It shall include all the necessary information to enable radiographs to be taken, processed, and interpreted to the requirements of this Standard. The documented radiographic procedure shall include the following information: (a)

Pipe size classified according to the dimensions, nominal bore, outside diameter and wall thickness.

(b)

Material specification.

(c)

Construction specification.

(d)

Acceptance specification or Standard, or both.

(e)

Method of weld identification.

(f)

Radiographic method designation (see AS 2177).

(g)

Equipment consisting of the following:

(i)

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(ii)

X-radiography Orthogonal panoramic Focal spot size Tube voltage Directional Focal spot size Tube voltage

Gamma radiography (i) Panoramic Source type Source size (ii) Directional Source type Source size

(h)

Film type.

(i)

Intensifying screens (type and thickness).

(j)

Diagnostic film length.

(k)

Source to film distance.

(l)

Source offset angle.

(m)

Image quality indicator (type and designation).

(n)

Undercut comparator.

(o)

Film processing/chemicals used.

(p)

Density range to be achieved.

18.2 METHOD OF QUALIFYING THE RADIOGRAPHIC PROCEDURE Radiographs of a complete weld shall be taken, processed and interpreted in accordance with the radiographic procedure. The weld may be selected from a number of welding procedure qualification and/or welder qualification welds or any production weld. The resultant radiograph(s) shall comply with the approved procedure.

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The height of reinforcement on this typical weld should approximate the maximum specified in Figure 15.4.2. Images of discontinuities observed on the radiograph shall be reported and recorded in accordance with Clause 17.6. The radiographic results of this weld shall be documented in a report having the same format as reports issued for inspection of production welds. 18.3 TEST CONDITIONS A test radiograph shall be made under conditions that simulate those to be encountered during construction. 18.4 RADIOGRAPHIC PROCEDURE SPECIFICATION DOCUMENTATION Where the assessment has demonstrated that the radiograph is satisfactory and discontinuities in the weld can be identified, a record to the effect that the radiograph made to the particular radiographic procedure complies with this Standard shall be maintained in the radiographic procedure specification documentation. 18.5 PERIOD OF VALIDITY

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A qualified radiographic procedure shall remain valid until it is withdrawn.

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SECT ION

78

19

U LTRASO N IC

E XAM I N AT I ON

19.1 MANUAL ULTRASONIC EXAMINATION 19.1.1 General The ultrasonic examination of a weld shall be performed using an approved documented and qualified procedure. For wall thicknesses in excess of 6 mm, the procedure shall comply with AS 2207. For wall thicknesses less than 6 mm, the test method shall be approved. The effectiveness of the ultrasonic procedure shall be demonstrated on a ‘mock up’ weld (or section thereof) that is typical of those made in production and containing artificial discontinuities in the form of appropriately placed side-drilled holes or machined grooves. 19.1.2 Purpose The purpose of an ultrasonic examination is to detect discontinuities in the weld, the heataffected zone, and in the parent metal immediately adjacent to the weld. Manual ultrasonic examination may be suitable— (a)

as an alternative to radiographic examination in pipe where the weld root geometry is consistent, such as is achieved with automatic welding methods;

(b)

as a supplement or an alternative to radiographic examination in the determination of particular discontinuities; and

(c)

where due to geometry or lack of access (radiographic examination is not appropriate).

19.1.3 Method The methods of test shall be appropriate to the type of weld to be examined. Where there is a possibility of transverse cracking in the weld, appropriate scanning patterns shall be employed. NOTE: The examination of the weld root area for discontinuities in single preparation welds poses problems associated with the root profile/penetration bead, which usually gives a strong ultrasonic reflection. This reflection needs to be separately identified from indications given by other discontinuities.

19.1.4 Surface preparation

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It is important to ensure that the minimum surface preparation is adequate for and appropriate to the level of testing. The shape of weld reinforcement may limit interpretation. In such cases additional surface preparation may need to be carried out. To fully evaluate a weld, surface preparations categorized by AS 2207 as SP1, SP2, SP3 and SP4 may be necessary. 19.1.5 Sensitivity Welds shall be scanned using an adequate level of sensitivity to ensure that all relevant discontinuities are detected. Discontinuities so detected shall be subsequently evaluated using the appropriate sensitivity and recording requirements as follows: (a)

Tiers 1 and 2 Evaluation sensitivity shall be Level 2 in accordance with AS 2207.

(b)

Tier 3 Engineering Critical Assessment (ECA). Evaluation sensitivity shall be Level 1 in accordance with AS 2207.

NOTE: See Clause 22 for further information about Tiers 1, 2 and 3.

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Irrespective of the evaluation sensitivity used, all cracks shall be sized for length and height. 19.1.6 Assessment An assessment of the discontinuities detected in a weld shall be made. Discontinuities shall be identified and symbolized. The terminology and abbreviations described in Clause 17.6 and AS 4749 may be used for this purpose. 19.1.7 Criteria of acceptance The weld shall comply with Clause 22. 19.1.8 Report The results of tests shall be reported in accordance with AS 2207. 19.1.9 Qualification of personnel Personnel shall be qualified in accordance with Clause 16.3. 19.2 MECHANIZED ULTRASONIC EXAMINATION 19.2.1 General The ultrasonic examination of a weld shall be made in accordance with DNV OS-F101. 19.2.2 Purpose The purpose of an ultrasonic examination is to detect discontinuities in the weld, the heataffected zone, and in the parent metal immediately adjacent to the weld. Mechanized ultrasonic examination may be used as the prime method for non-destructive examination of manual and mechanized welded pipeline girth welds where the thickness exceeds 6 mm or, for lesser thicknesses, where approved and a satisfactory level of performance can be demonstrated. 19.2.3 Method The weld shall be examined by scanning from both sides of the weld from the external surface in accordance with Appendix E of DNV OS-F101. 19.2.4 Reference standard

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Calibration shall be carried out on a uniquely identified reference standard manufactured from a sample of unflawed project-specific line pipe representing the pipe being tested. The pipe used for the reference standard shall be traceable to the rolling mill, steel manufacturer, steel grade and be of the same nominal dimensions as the pipe being tested. The dimensions of the reference standard shall be clearly specified in the procedure and the size, location, orientation, form, method of manufacture and manufacturing tolerances of each of the reference reflectors shall be detailed. If pipe is procured for a project where there are a number of suppliers or manufacturing routes or different material grades required, the shear wave acoustic velocity in the longitudinal and transverse directions shall be determined for each supplier, manufacturing route and grade. If the shear wave acoustic velocities deviate by more than 5% from that determined for the reference standard, either— (a)

additional reference standards shall be made; or

(b)

software shall be reconfigured to compensate for the deviations.

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19.2.5 Reference reflectors Reference reflectors shall be machined in the reference standard. The size and location of reference reflectors shall be determined for the project after the welding procedure has been established. These machined reflectors shall be designed and located to simulate the following: (a)

Lack of root fusion

(b)

Lack of side wall fusion

(c)

Root undercut

(d)

Porosity if B-scan or C-scan imaging is used.

Reference reflectors shall be no larger than the maximum acceptable defects they simulate. Incompletely filled groove and external undercut shall be evaluated by visual examination. 19.2.6 Procedure 19.2.6.1 Static calibration Static calibration shall be carried out at the commencement of each production run and in accordance with the following: (a)

The system shall be optimized for field inspection using the relevant reference block.

(b)

All transducers shall be positioned at the appropriate stand-off position and adjusted to provide an optimized signal from the relevant calibration reflector and gain adjusted to the specified percentage of full screen height.

(c)

The gain level for each transducer shall be recorded as the primary reference sensitivity for respective transducers.

19.2.6.2 Dynamic calibration Dynamic calibration shall be carried out under production conditions and in accordance with the following: (a)

Where the temperature difference between the reference standard surface, probe wedge material and examination surface causes shifts in the refracted angle that results in the system not being able to provide the required zone discrimination, a means of regulating the temperature of the reference standard or probe wedge material, or both, shall be employed.

(b)

The rotational speed of the test unit shall be the same as for production testing.

(c)

The same couplant medium and couplant delivery system shall be used.

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Dynamic calibration shall be carried out at intervals in accordance with Clause 19.2.7. 19.2.7 Calibration verification frequency In addition to the requirements of Appendix E of DNV OS-F101, calibration shall be verified by dynamic test on the reference standard and the scan recorded at the following intervals: (a)

Commencement of a shift.

(b)

Completion of a shift.

(c)

Before continuing testing after any break, e.g. meal times.

(d)

After every tenth weld or every 2 h, whichever comes first.

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(e)

Unless it can be demonstrated that the testing system is tolerant to wider variations in temperature while maintaining sensitivity and accuracy of detection, whenever there is a difference of temperature of the test pipe of more than 10°C from the temperature of the reference standard at the last calibration verification.

(f)

After any change of components or repair or adjustment of the system.

(g)

After any change of wall thickness, grade or change to material from another supplier.

19.2.8 Criteria of acceptance The weld shall comply with Clause 22. 19.2.9 Report The results of tests shall be reported in accordance with Appendix E of DNV OS-F101. The raw data from the test may be presented as a computer graphic, graphical print out or C-scan map. If data is stored electronically and computer presentations are used for reporting purposes, the data shall be stored in a form that allows re-creation of computer screen images or strip chart or other hard copy presentations at the original resolution so as to enable re-evaluation of the test data by a third party. 19.2.10 Retention of raw data

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The raw data shall be stored for a minimum of three years. The medium used for such storage shall be suitable for that purpose. In order to guard against corruption or damage to electronic data files it is recommended that duplicate copies be held.

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S E C T I O N

2 0

M A G N E T I C T E ST IN G

PA RT IC L E

20.1 PURPOSE The purpose of a magnetic particle test is to locate discontinuities that are on or near the surface of the weld and adjacent parent metal. 20.2 METHOD Magnetic particle testing shall be carried out in accordance with AS 1171 and the following: (a)

Method of magnetization The method of magnetization shall be magnetic flow (sustained).

(b)

Cleaning after testing Magnetic particle medium shall be removed after testing. A corrosion inhibitor may be applied.

(c)

Test report A test certificate shall be issued.

20.3 QUALIFICATION OF PERSONNEL Personnel shall be qualified in accordance with Clause 16.3. 20.4 CRITERIA OF ACCEPTANCE

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The weld shall not contain any discontinuities that are on or near the surface of a weld and adjacent parent metal that do not comply with Clause 22.

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SE C T I ON

2 1

DY E - PE N E T RA N T

AS 2885.2—2007

T E ST I N G

21.1 PURPOSE The purpose of dye-penetrant testing is to locate discontinuities that are open to the surface of a weld and adjacent parent metal. 21.2 METHOD Dye-penetrant testing shall be carried out in accordance with AS 2062 and the following: (a)

Type of testing medium The type of testing medium shall contrast in colour and be water washable.

(b)

Cleaning after testing The penetrant and the developer shall be removed after testing. A corrosion inhibitor may be applied.

(c)

Reports A test certificate shall be issued.

21.3 QUALIFICATION OF PERSONNEL Personnel shall be qualified in accordance with Clause 16.3. 21.4 CRITERIA OF ACCEPTANCE

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The weld shall not contain any discontinuities that are open to the surface of a weld and adjacent parent metal that do not comply with Clause 22.

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SECT I O N 2 2 FOR G I RTH

84

C R IT E R I A O F A CCE PT A N CE WE LD D I SCO NT I NU I T I ES

22.1 GENERAL The criteria of acceptance for girth weld discontinuities in this Standard are based on a three-tier system. The choice of which tier is to be used shall be approved. Figure 22.1 shows the procedure for selection of acceptance criteria. Welds that comply with the selected criteria of acceptance shall be deemed to comply with this Standard. Production welds that do not comply with the selected criteria shall be repaired (see Clause 23 or 24) or cut out (see Clause 25). Acceptance criteria are as follows: (a)

Tier 1 (see Clause 22.2) Tier 1 acceptance criteria are based on commonly achievable standards of good workmanship. Such acceptance criteria are very similar to ANSI/API 1104, which is the de facto international Standard of workmanship for pipeline girth welds. They are also similar to the requirements of the superseded editions of this Australian Standard except for wall thicknesses less than 7 mm where limits on embedded defects have been reduced from 50 mm to 25 mm in length, on the basis of Australian research. NOTE: Tier 1 may be used without any special pre-qualification requirements. It is expected that Tier 1 will be most commonly applied where the special requirements of the other tiers are not justified by the scale of the project.

(b)

Tier 2 (see Clause 22.3) Tier 2 acceptance criteria are based on generalized fitnessfor-purpose criteria. Weld discontinuities that would not be acceptable under the workmanship standards of Tier 1 may be acceptable to Tier 2.

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The principal basis for the Tier 2 criteria is the European Pipelines Research Group (EPRG) EPRG guideline on defects in transmission pipeline girth welds, April 1994 edition. Australian experience, which formed the basis for the 1987 edition of this Standard, and the results of recent Australian research work undertaken by the CRC for Welded Structures have also been taken into account (see also Preface). The use of Tier 2 acceptance criteria requires certain special requirements to be met. The most important of these is that because the limits are based on experimentally validated plastic collapse considerations, the welds have to be shown to have adequate toughness in order to ensure that failure does not occur by brittle fracture. Australian research has shown that when strength matching can be demonstrated the Tier 2 limits can be extended down to 5 mm wall thickness and up to grade X80. However in practice the demonstration of strength matching is difficult, and this Standard (see Clause 22.3 Note 1) only allows the application of Tier 2 grades above X65 when wide plate or full section pipe tensile tests are used to demonstrate overmatching. The application of Tier 2 to wall thickness less than 7 mm is not allowed. (c)

Tier 3 (see Clause 22.4) Tier 3 acceptance criteria are fitness-for-purpose criteria developed from an engineering critical assessment (ECA) carried out expressly for the project concerned. The use of approved engineering critical assessment (ECA) procedures for the development of fitness-for-purpose acceptance criteria for particular circumstances has been permitted by this Australian Standard for some time. This means that a twotier system in which ECA was Tier 2 has already been established.

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NOTES: 1

This new edition of the Standard retains the option of using ECA procedures for particular circumstances, and this is designated as Tier 3.

2

It is likely that in most cases, because actual operating conditions will be known and therefore assumptions do not need to be as conservative as in the generalized case used in Tier 2, the criteria of Tier 3 may, subject to satisfactory levels of fracture toughness, permit the acceptance of more severe discontinuities than both Tiers 1 and 2.

3

BS 7910 and API579 describe ECA procedures that are suitable for use for this application. Alternatively, wide plate tests or full-scale tests could be used.

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Pre-existing laminar imperfections in the parent metal, which comply with the requirements of ANSI/API Spec 5L, shall be acceptable, unless they do not meet the requirements for ultrasonic inspection of Clause 19.

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NOTE: The decision tree does not show access to Tier 2 acceptance criteria from the workmanship standards of Tier 1. This is because in normal circumstances the prerequisite conditions in Clause 22.3.1 would not have been met, which is not intended to prevent the application of quality control practices aimed at the normal achievement of workmanship standards whilst allowing a fall-back position to Tier 2. In such circumstances, the abovementioned prerequisite conditions will need to be met.

FIGURE 22.1 PROCEDURE FOR SELECTION OF CRITERIA FOR ACCEPTANCE FOR GIRTH WELD DISCONTINUITIES

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22.2 TIER 1 CRITERIA—WORKMANSHIP STANDARD 22.2.1 Inadequate penetration Inadequate penetration without high/low lack of penetration (LP) is defined as the incomplete filling of the weld root. This condition is shown schematically in Figure 22.2.2(a). LP shall be unacceptable when any of the following conditions exist: (a)

The length of an individual indication of lack of penetration (LP) exceeds 25 mm.

(b)

The aggregate length of indications in any continuous 300 mm length of weld exceeds 25 mm.

(c)

The aggregate length of indications of lack of penetration (LP) exceeds 8% of the weld length in any weld less than 300 mm in length. NOTE: See Table 22.2.7 for the summary of Tier 1 acceptance criteria for girth weld discontinuities.

22.2.2 Inadequate penetration due to high-low Inadequate penetration (LP) due to high/low LP(H/L) is defined as the condition that exists when one edge of the root is exposed (or unbonded) because adjacent pipe or fitting joints are misaligned, and where ‘high/low’ (H/L) is a condition where the pipe or fitting surfaces are misaligned. This condition is shown schematically in Figure 22.2.2(b). LP(H/L) is deemed not to be a defect and shall be acceptable unless incomplete fusion is also present. 22.2.3 Incomplete fusion Incomplete fusion, lack of fusion at the root (LR) or lack of fusion at the side (LS) is defined as a discontinuity between the weld metal and the base metal that is open to the surface or buried for LS. This condition is shown schematically in Figure 22.2.2(c). LR or LS shall be unacceptable when any of the following conditions exist: (a)

The length of an individual indication exceeds 25 mm.

(b)

The aggregate length of indications in any continuous 300 mm length of weld exceeds 25 mm.

(c)

The aggregate length of indications exceeds 8% of the weld length in any weld less than 300 mm in length.

22.2.4 Incomplete fusion due to cold lap

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Incomplete fusion due to cold lap [lack of inter-pass fusion (LI) or lack of side wall fusion (LS)] is defined as a discontinuity between two adjacent weld beads, or between the weld metal and the base metal that is not open to the surface. This condition is shown schematically in Figure 22.2.2(d) and Figure 22.2.2(f). It shall be unacceptable when any of the following conditions exist: (a)

The length of an individual indication exceeds 25 mm for δN 8% weld length

>8%

>8% weld length

Aggregate length/width/diameter in weld 3 mm

>50 mm or width >2 mm

Max. length or width >6 mm or thinner wall thickness and density of BT’s image exceeds that of thinnest adjacent base metal

>8% weld length

>13 mm

>50 mm

—

—

—

—

(continued)

*More than one of any size present and the density of more than one of the images exceeds that of the thinnest adjacent base metal

>13 mm where density of BT’s image exceeds that of thinnest adjacent base metal

Any length acceptable if radiographic density of internal cavity does not exceed that of thinnest adjacent base metal. Otherwise burn through criteria apply

>50 mm

Incomplete fusion due to cold lap (LI) or lack of side wall fusion (LS)

22.2.4

>25 mm

δ N 25 mm

Inadequate penetration due to H/L (LP(H/L))

22.2.2

>25 mm

Individual length/width/diameter

δ N ≥7 mm

Inadequate penetration (without H/L) (LP)

Type of discontinuity

22.2.1

Clause

Acceptability limits

This summary of Tier 1 acceptance criteria for girth weld discontinuities is provided for the convenience of the user and is to be read in conjunction with Clause 22.2.

SUMMARY OF TIER 1 ACCEPTANCE CRITERIA FOR GIRTH WELD DISCONTINUITIES

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Hollow bead (HB)

22.2.8(c)

22.2.10(a)

22.2.9

Cluster (PG):

22.2.8(b)

—finish pass

—other than finish pass

Individual gas pore (GP)

Undercutting (SUC) all thicknesses if depth >0.8 mm

Cracks (KL, KT, KE, KC)

If HB reduces weld thickness to less than that of thinner parent, or by the width of the discontinuity then unacceptable if

Porosity:

—

IL+IN

—

—

2 × lesser thickness and width half lesser thickness >8% weld length

—

Aggregate length/width/diameter in weld 50 mm

>13 mm, or through thickness dimension of individual pore >30% of the thickness

—

>20%

—

—

>50 mm

>50 mm

— (continued)

All cracks shall be unacceptable except shallow crater or star crack with a maximum dimension of 4 mm

or individual lengths each >6 mm are separated by 13 mm

>13 mm dia., or through thickness dimension of individual pore >30% of the thickness

See Item (a)

Through thickness dimension of individual pore >30% of the thickness or any dimension of surface breaking porosity >1.5 mm

Wagon tracks shall be considered a single indication unless the width of either of them exceeds 1 mm. In that event, they shall be considered separate indications.

—

>3 × lesser thickness or width >2 mm

Individual length/width/diameter

TABLE 22.2.7 (continued)

IN

50 mm (individual or aggregate)

—

>20% (individual or aggregate)

>8% (individual or aggregate)

—

—

Aggregate length/width/diameter in weld 25 mm (individual or aggregate)

—

>20% weld length

>20% weld length

Aggregate length/width/diameter in any continuous 300 mm length of weld

Acceptability limits

Pipe or fitting discontinuities (arc burn, longitudinal seams and other defects)—repair or removal at the direction of the pipeline licensee

Coincident discontinuities without length limit

2.2.2.13(b)

22.2.14

Coincident discontinuities with length limit

22.2.13(a)

δN ≥7 mm

Accumulation (exclude incomplete penetration due to hi lo and undercutting) δ N 20% weld length

22.2.12

δ N 0.4 mm

22.2.10(c)

>20% weld length

Root slag intrusion—shall be classified as undercutting, see 22.2.10

δ N ≥7 mm; if depth >0.8 mm

22.2.10(b)

Individual length/width/diameter

TABLE 22.2.7 (continued)

22.2.11

Type of discontinuity

Clause

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22.3 TIER 2 CRITERIA—GENERALIZED FITNESS-FOR-PURPOSE STANDARD 22.3.1 General Discontinuities, other than cracks that do not reduce the weld thickness to less than 90% of the thinner of the parent metal thicknesses, are acceptable. The generalized fitness-for-purpose criteria of Tier 2 are based on limit load/net section plastic collapse considerations. All of the following requirements apply: (a)

Either— (i)

the welds shall be made in their entirety with E4110 electrodes; or

(ii)

charpy V-notch impact tests, performed as part of the welding procedure qualification test, shall meet a minimum requirement of 40 J minimum average and 30 J minimum individual at the lowest design temperature at which the combined stress exceeds 30% SMYS.

The requirement in Item (ii) is applicable to full-size test pieces. The test piece size shall be the largest standard size that can be obtained. The requirement shall be reduced pro rata according to the cross-sectional area of the test piece (see Clause 6.4.7). (b)

For welds in material greater than 13 mm thick, crack tip opening displacement (CTOD) tests shall be performed in accordance with AS 2205.7.3 and shall meet a requirement of 0.15 mm minimum average and 0.10 mm minimum individual at the lowest design temperature at which the combined stress exceeds 30% SMYS (see Clause 6.4.8).

(c)

Transverse butt tensile tests shall be performed as part of the welding procedure qualification test with the weld reinforcement removed by dressing. The tests are acceptable if the specimens fail in the pipe material or if the specimens break in the weld metal with a tensile strength greater than, or equal to, the specified minimum tensile strength of the pipe material.

(d)

The nominal thickness shall lie within the range 7 mm to 25 mm.

(e)

Each defect is assumed to be confined to a single weld pass not greater than 3 mm in depth. If there is a suspicion of a single defect being greater than 3 mm then Tier 2 acceptance criteria shall not be applied. These criteria shall only be applied to pipeline girth welds between pipes of equal grade and nominal thickness.

(f)

The pipe SMYS shall not exceed 448 MPa.

(g)

Service conditions shall not include onerous fatigue conditions (see Note 2).

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NOTES: 1

The weld discontinuity acceptance limits in this Standard are based on those in the EPRG Guidelines referred to elsewhere and also on Australian research by the CRC for Welded Structures, which has assessed thin-walled high-strength pipeline girth welds. The values of defect length are founded upon plastic collapse calculations that include assumptions regarding the flow stress and the yield/tensile ratio of the girth weld metal and the pipe parent metal, and the requirement that the yield strength of the weld metal be equal or exceed that of the parent pipe. The Australian research has demonstrated that a certain level of weld metal yield strength undermatching can be tolerated within the requirements of Tier 2 while maintaining defect tolerance. It should be noted that, as mentioned in Paragraph C3 of Appendix C, the notched tensile test, which was used to determine yield strength matching, has been removed from the Standard along with a return of Tier 2 criteria to those in the 1995 edition of this Standard; however, the wide plate and full section pipe tension tests can still be used to define defect limits for particular weld consumable pipe grade combinations and can be applied to those pipe grades now excluded from Tier 2.

2

Normal daily pressure fluctuations due to line packing are not deemed to constitute onerous fatigue conditions.

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AS 2885.2—2007

22.3.2 Tier 2 acceptance criteria The Tier 2 acceptance criteria are described in Table 22.3.2(A) and Figure 22.3.2. Equations to the lines in Figures 22.3.2 are set out in Table 22.3.2(B). Tier 2 Acceptance limits for some common pipe sizes are given in Table 22.3.2(C). TABLE 22.3.2(A) WELD DISCONTINUITY ACCEPTANCE LIMITS FOR TIER 2 Type of discontinuity

Tier 2 acceptance criteria

External profile (non-planar)

The maximum height of external weld reinforcement shall comply with Figure 15.4.2 The weld shall be completely filled

Planar root concavity (see Note 3)

Root concavity that does not reduce the thickness of the weld below 90% of the thickness of the parent metal shall be acceptable regardless of length

Non-planar root cavity (see Note 4)

Root concavity that reduces the thickness of the weld below 90% of the thickness of the parent metal shall be assessed against the all defects line in Figure 22.3.2

Non-planar undercut

Depth less than 0.8 mm—no limit

Planar undercut

Depth greater than 0.8 mm—planar defect in Figure 22.3.2

Inadequate penetration and all Planar defect in Figure 22.3.2 lack of fusion defects (planar) Cracks (planar)

Not allowed

Crater cracks (see Note 5) (non-planar)

Maximum dimension of 4 mm

Burn-through (non-planar)

Burn-throughs less than 6 mm long and less than one weld pass (3 mm) depth have no structural significance and are not limited under Tier 2. Burn-throughs longer than 6 mm shall be assessed using the root concavity limitations if the depth is less than one weld pass. Burn-throughs more than one weld pass (3 mm) deep are not allowed

Porosity (non-planar)

The depth of individual gas pores in the through-thickness dimension exceeds 30% of the wall thickness.

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Other porosity is of no structural significance and is not limited by Tier 2 Hollow bead (see Notes 3, 4 & 7) (non-planar)

All defects in Figure 22.3.2. Hollow bead that does not reduce the thickness of the weld below 90% of the thickness of the parent metal shall be acceptable regardless of length

Slag inclusions (see Note 6) (non-planar)

All defects in Figure 22.3.2

Interaction (planar and non-planar)

If the defect is separated from a planar defect by a distance smaller than the length of the shorter of the two defects, then re-categorize as a single planar defect (defined for the purposes of Figure 22.3.2 as an interacting planar defect) of length equal to the two individual lengths plus separation. Figure 22.3.2 gives limits for interacting planar defects

Coincident defects (see Note 2)

Discontinuities that have length limits in this Table are unacceptable regardless of length when they are superimposed in the same position in the weld so that the total assumed defect depth at that position exceeds one weld pass (3 mm) Discontinuities that do not have length limits in this Table are acceptable regardless of length when they are superimposed in the same position in the weld provided that they do not collectively reduce the thickness of the weld below 90% of the thickness of the parent metal

Systematic and repeated defects

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At the option of the pipeline licensee, systematic and repeated occurrences of defects of workmanship may be sentenced according to the requirements of Tier 1

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NOTES TO TABLE 22.3.2(A): 1

Clause 22.2 requires that discontinuities that do not reduce the remaining weld thickness below 90% of the thinner parent metal thickness be ignored. This applies to all types of discontinuity in Table 22.3.2(A).

2

The discontinuities that do not have length limits are as follows: (a)

Defects that do not reduce weld thickness below 90% of the thinner parent metal thickness.

(b)

Undercut less than 0.8 mm, where the depth does reduce the weld thickness below 90%. This can occur in thickness less than 8 mm.

(c)

Porosity having maximum pore size less than 3 mm.

3

The remaining weld thickness relative to the 90% minimum limit when the volumetric defects root concavity, burnthrough, and hollow bead are present is a matter for the radiographer’s judgment, assisted by reference to the density of the parent metal and the images of the grooves on the undercut comparator shim.

4

Root concavity, burn-through, and hollow bead that reduce the remaining weld thickness below 90% of the thickness of the parent metal are assumed to be one weld pass deep.

5

As per Tier 1.

6

Includes wagon tracks.

7

The permitted reduction in weld metal thickness to 90% of parent metal thickness for hollow bead is allowed in the Tier 2 fitness-for-purpose acceptance criteria in recognition of the demonstrated achievement of matching strength in the procedure qualification requirements for Tier 2.

TABLE 22.3.2(B) EQUATIONS TO THE LINES IN FIGURE 22.3.2

Line

Equation

Coordinates at maximum defect length Wall thickness mm

Defect length %

Total—all defects

3.91 × (wall thickness) + 0.11

12.8

50

Total—all planar defects

2.37 × (wall thickness) − 5.50

13.0

25

Interacting planar defect

1.54 × (wall thickness) − 1.92

17.5

25

Individual planar defect

1.04 × (wall thickness) − 2.48

26.5

25

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NOTE: These equations apply only to the sloping portion of the lines.

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AS 2885.2—2007

TABLE 22.3.2(C) TIER 2 ACCEPTANCE LIMITS FOR SOME COMMON PIPE SIZES millimetres Maximum acceptable discontinuity length

Pipe diameter

Individual planar defects, i.e., undercut deeper than 0.8 mm and all inadequate penetration and lack of fusion defects

Interacting planar defects

Wall thickness

Total all defects in any weld

7.1 7.9 8.7

192 213 235

78 91 104

192 213 235

34 39 45

62 70 79

9.5 11.0 12.7

256 297 342

117 142 169

256 297 342

51 62 74

87 103 121

7.1 7.9 8.7

239 266 293

97 113 130

239 266 293

42 49 56

77 88 98

9.5 11.0 12.7

320 370 427

146 176 211

320 370 427

63 77 92

109 129 151

7.1 7.9 8.7

284 316 347

115 135 154

284 316 347

50 58 67

92 104 117

9.5 11.0 12.7

379 439 507

173 209 250

379 439 507

75 91 109

129 153 180

7.1 7.9 8.7

312 347 382

127 148 169

312 347 382

55 64 73

101 115 128

9.5 11.0 12.7

417 482 557

190 230 275

417 482 557

83 100 120

142 168 197

7.1 7.9 8.7

355 395 435

144 169 193

355 395 435

63 73 84

115 131 146

9.5 11.0 12.7

475 550 635

217 262 314

475 550 635

94 114 137

162 192 225

7.1 7.9 8.7

400 445 490

163 190 217

400 445 490

70 82 94

129 147 165

9.5 11.0 12.7

535 619 715

244 295 353

535 619 715

106 129 154

182 216 253

219

273

324

356

406

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Total all planar defects in any weld

Volumetric defects that reduce wall thickness below 0.90δ N, i.e., certain root concavity, burnthrough, and hollow bead conditions

457

NOTE: Table 22.3.2(C) lists Tier 2 weld discontinuity acceptance limits for discontinuities listed in Table 22.3.2(B) and shown graphically in Figure 22.3.2. The values have been calculated from the equations listed in Table 22.3.2(B).

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The equations to the lines are given in Table 22.3.2(B).

Table 22.3.2(C) gives an example by tabular presentation of the acceptance limits for some common wall thicknesses.

The information for thickness less than 7 mm is shown for illustration purposes only. Tier 2 is not applicable to thickness less than 7 mm.

3

4

FIGURE 22.3.2 WELD DISCONTINUITY ACCEPTANCE LIMITS FOR TIER 2

This Figure is adapted from Figure 4.1 of The European Pipeline Research Groups proposed ‘Guidelines on pipeline girth weld defects’.

2

—

—

1

NOTES:

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AS 2885.2—2007

22.4 TIER 3 CRITERIA—ENGINEERING CRITICAL ASSESSMENT The discontinuity acceptance criteria may be determined using an approved engineering critical assessment procedure or other approved method. The method shall be documented. For welds that may be subject to displacement controlled loading, this process shall include an assessment of weld strength matching. In pipe grades up to and including X65, weld strength matching may be deemed to be achieved on the basis of experience. For higher grades an experimental method, such as wide plate testing, or full scale testing shall be used. NOTE: BS 7910 describes ECA procedures that are suitable for use for this application. ‘PIPESAFE’, a software package developed by the Cooperative Research Centre for Welded Structures (CRC-WS), which is available from the Welding Technology Institute of Australia, is an approved method for conducting engineering critical assessments on pipeline girth welds. Application of ECA procedures, such as BS 7910, should be approached with caution where weld strength mismatch is encountered since in these situations strain can be concentrated in the weld metal. Factors to be considered are the effect of strength matching on fracture toughness measurement, relative difference between the work hardening rates of the weld and parent metals and defect type, e.g., shallow and part wall thickness located in weld or HAZ. Before application of such ECA methods, reference should be made to expositions on the significance of weld strength matching, e.g., BS 7910. Engineering critical assessment is an active area of research so that expert knowledge may be of benefit in particular situations. Generally where displacement controlled loading is not expected and the stress in the weld is less than its yield strength then such procedures may be applied with safety. It should be noted, however, that undermatched welds have lower defect tolerance than overmatched welds since in the latter case yielding of the pipe may be possible without weld fracture.

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Wide plate and full-scale tests are also approved methods when performed by personnel with proven fracture mechanics expertise.

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102

S E C T I O N 2 3 RE PA I R O F A N UNACCEPTAB L E WE L D 23.1 GENERAL A weld containing a defect shall be repaired or cut out. 23.2 REPAIR METHODS A repair to a weld containing a defect shall be made using an approved repair procedure documented and qualified in accordance with Clause 5. Repairs to repair welds are not prohibited by this Standard; however, they shall be subject to the specific approval of a welding engineer on a case by case basis. The repair procedure should be developed in consideration of the material in Appendix E in general, and in particular Paragraph E9.4. The procedure specification shall include details of the following: (a)

The means of removing the defect, including the length of sound metal to be removed at each end.

(b)

Welding procedure items according to Clause 5.

(c)

The means of providing assurance that HACC will not be encountered.

(d)

The non-destructive examination methods used to determine that the defect is completely removed, including the length of overlap of the repaired length.

(e)

The method and the timing of non-destructive examination of the completed repaired production weld.

(f)

Hardness test results on the repair section of the repair procedure test weld.

(g)

Macro test results on the repair section of the repair procedure test weld.

23.3 QUALIFICATION OF THE REPAIR WELDING PROCEDURE

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The following applies: (a)

Qualification of a repair weld shall comply with the methods of qualification identified in Clause 5.3.

(b)

Where qualification by testing is required, a test weld shall be prepared to represent the location and depth of repair.

(c)

Repair weld procedures that involve a full thickness repair may be used for partial thickness repairs.

(d)

Repairs involving a single pass only shall require separate qualification.

23.4 INSPECTION The repaired weld shall be inspected in accordance with Clause 15 and Clause 16. 23.5 CRITERIA OF ACCEPTANCE The criteria of acceptance of a repaired weld shall be as specified in Clause 22.

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103

SECT ION

24

REMOVA L

AS 2885.2—2007

OF

AN

ARC

BURN

24.1 GENERAL An arc burn on pipe that is to be operated at a pressure that produces a hoop stress equal to or greater than 40% SMYS shall be— (a)

repaired by grinding; or

(b)

cut out.

24.2 REPAIR BY GRINDING Where a repair is made by grinding, the area of the metallurgical notch created by the arc burn shall be removed completely, and the remaining wall thickness shall be not less than 90% of the nominal wall thickness of the pipe. 24.3 METHOD OF INSPECTION The ground area shall be etched with either a 10% solution of ammonium persulfate or a 5% solution of nital, and shall be visually inspected. If a blackened spot appears, the metallurgical notch produced by the arc burn has not been removed. 24.4 CRITERIA OF ACCEPTANCE The swabbed area shall be free of any black spot. 24.5 CLEANING AFTER TESTING

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Regions that have been etched shall be cleaned after testing is complete. A corrosion inhibitor may be applied.

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SECT ION 25 CUTT I NG OUT AN UNACCEPTAB L E WE L D O R AN ARC B URN A permanent repair shall be made by cutting out a cylindrical piece of pipe containing the unacceptable weld or arc burn and— (a)

making new weld preparations and welding the joint; or

(b)

replacing it with another cylinder of pipe that complies with the engineering design.

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Where a repair is made on a tested pipeline, a cylinder cut from pre-tested pipe shall be used.

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105

S E C T I ON

2 6

AS 2885.2—2007

RE CO RD S

A record shall be made showing the following, by relation to a kilometre post, engineering station, or geographical feature: (a)

The number of butt welds made.

(b)

The number and location of welds that have been subjected to non-destructive examination. The type(s) and extent of non-destructive examination shall be noted for each weld.

(c)

The number and location of welds that failed to comply and were subsequently successfully repaired.

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This record shall be retained and maintained by the pipeline licensee until the pipeline is abandoned or removed.

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APPENDIX A

ITEMS REQUIRING APPROVAL (Normative)

Clause

Subject

Item requiring approval

1.2

Qualification and approval

Welding procedure Delegation of authority to approve

3.1

Post-weld heat treatment

An alternative method of post weld heat treatment other than a method specified in AS 1210

6.4.2

Fracture toughness test criteria

Type, method and location of test, preparation of test specimens and criteria of acceptance

11.4

Supervision of production welds

Qualification of welding supervisor

11.21

Identification of production welds

Manner in which production welds are identified.

12.1

Welding procedures for welding on live pipelines

Welding procedures and operations

13.8

Heat input for welding on live pipelines Heat input (arc energy) and electrode size.

13.9

Qualification for welding on live pipelines

Welding procedure for in-service welds, including pressure and cooling effects from fluid flow in the pipeline.

12.2

Safety for welding on live pipelines

Earthing procedure

13.4

Welding onto an in-service pipeline

Safety procedures

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(continued)

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AS 2885.2—2007

(continued) Clause

Subject

Item requiring approval

12.3

Hot repair of a leaking gas-filled pipeline

Procedures for the following: •

Detection of explosive mixtures

•

Means of maintaining work site to mainline valve communication

•

Method of regulating gas pressure

Pre-welding ultrasonic examination

Method of examination and reference sensitivity

14.2

Assessment of production and repair welds

Qualification and experience of personnel involved in welding inspection

16.5

Non-destructive examination (NDE)

Amount and specified location of NDE

16.6

Exemption from NDE

Alternative magnetic particle or dyepenetrant test method

17.1

Radiographic examination

Examination procedure

19.1.1

Manual ultrasonic examination

Examination procedure

19.2.1

Mechanised ultrasonic examination

Examination procedure

22.1

Criteria of acceptance for girth weld discontinuities

Choice of tier to be used as acceptance criteria

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13.6.2

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APPENDIX B

LIST OF REFERENCED DOCUMENTS (Normative)

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AS 1170 1170.4

Minimum design loads on structures Part 4: Earthquake loads

1171

Non-destructive test—Magnetic particle testing of ferromagnetic products, components and structures

1210

Pressure vessels

1544 1544.2

Methods for impact tests on metals Part 2: Charpy V-notch

1545

Methods for the calibration and grading of extensometers

1697

Gas transmission and distribution systems

1710

Non-destructive testing—Ultrasonic testing of carbon and low alloy steel plate—Test methods and quality classification

1796

Certification of welders and welding supervisors

1858 1858.1

Electrodes and fluxes for submerged-arc welding Part 1: Carbon steels and carbon-manganese steels

2062

Non-destructive testing—Penetrant testing of products and components

2177

Non-destructive testing—Radiography of welded butt joints in metal

2205 2205.1 2205.2.1 2205.3.1 2205.5.1 2205.6.1 2205.7.1 2205.7.3

Methods for destructive testing of welds in metal Part 1: General requirements for tests Part 2.1: Transverse butt tensile test Part 3.1: Transverse guided bend test Part 5.1: Macro metallographic test for cross-section examination Part 6.1: Weld joint hardness test Part 7.1: Charpy V-notch impact fracture toughness test Part 7.3: Fracture mechanics toughness tests (KIc , critical CTOD and critical J values)

2207

Non-destructive testing—Ultrasonic testing of fusion welded joints in carbon and low alloy steel

2314

Radiography of metal—Image recommendations for their use

2706

Numerical values—Rounding and interpretation of limiting values

2885 2885.1

Pipelines—Gas and liquid petroleum Part 1: Design and construction

3998

Non destructive testing—Qualification and certification of personnel

4041

Pressure piping

4564

Specification for general purpose natural gas

AS 4749

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quality

indicators

(IQI)

and

Non-destructive testing—Terminology of and abbreviations for fusion weld imperfections as revealed by radiography www.standards.org.au

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AS/NZS 1167 1167.2

Welding and brazing—Filler metals Part 2: Filler metal for brazing and braze welding

1553

Covered electrodes for welding

2717 2717.1

Welding—Electrodes—Gas metal arc Part 1: Ferritic steel electrodes

2885 2885.5

Pipelines—Gas and liquid petroleum Part 5: Field pressure testing

3992

Pressure equipment—Welding and brazing qualification

3834 3834.1 3834.2

Quality requirements for welding—Fusion welding of metallic materials Part 1: Guidelines for selection and use Part 2: Comprehensive quality requirements

4855

Welding consumables—Covered electrodes for manual metal arc welding of non-alloy and fine grain steels—Classification

4857

Welding consumables—Covered electrodes for manual metal arc welding of high strength steels—Classification

AS/NZS ISO 17632

ISO 1027

Welding Consumables—Tubular cored electrodes for gas shielded and non-gas shielded metal arc welding of non-alloy and fine grain steels— Classification Radiographic image quality indicators for non-destructive testing— Principles and identification

ANSI/AWS A5.1

Specification for carbon steel electrodes for shielded metal arc welding

A5.5

Specification for low alloy steel covered arc welding electrodes

A5.17

Specification for carbon steel electrodes and fluxes for submerged arc welding

A5.18

Specification for carbon steel electrodes and rods for gas shielded arc welding

A5.20

Specification for carbon steel electrodes for flux cored arc welding

A5.28

Specification for low alloy steel filler metals for gas shielded arc welding

BS 7910 Accessed by GHD PTY LTD on 05 Aug 2009

AS 2885.2—2007

7448 7448.2 DIN 54109 54109.2

Guide on methods for assessing the acceptability of flaws in metallic structures Fracture mechanics toughness test Part 2: Method for determination of K Ic, critical CTOD and critical J values of welds in metallic materials Non-destructive examination—Imagine quality of radiography Part 2: Recommended practice for determining image quality values and image quality classes

ANSI/API 1104

Welding of pipelines and related facilities

Spec 5L

Specification for line pipe

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ANSI/ASME B31.3

110

Liquid transportation systems for hydrocarbons liquid petroleum gas, anhydrous ammonia and alcohols

B31.8

Gas transmission and distribution piping systems

Section IX

Qualification Standard for welding, brazing procedures, welders, brazers and welding and brazing operators

NACE∗ MR-0175

Sulfide stress cracking resistant-metallic materials for oilfield equipment

WTIA

Technical Note 1 The weldability of steels Technical Note 3 Care of manual arc-welding steel electrodes Technical Note 20 Repair of pipelines

DNV OS-F101 Submarine pipeline systems

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EPRG†

The EPRG guideline on defects in transmission pipeline girth welds

∗ NACE is the designator for the American National Association of Corrosion Engineers. † EPRG is the designator for the European Pipeline Research Group.  Standards Australia

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AS 2885.2—2007

APPENDIX C

SELECTION AND SPECIFICATION OF CELLULOSIC WELDING ELECTRODES (Informative) C1 SCOPE This Appendix gives advisory information on the selection and specification of cellulosic manual metal arc welding (MMAW) electrodes for pipeline welding. C2 BACKGROUND Cellulosic (EXX10) electrodes have been the primary choice for the welding of pipelines because of their unique combination of high welding speeds and their ability to make single-sided full penetration welds. The principal disadvantage of EXX10 electrodes is the high level of hydrogen they contribute to the weld metal, and the resulting risk of hydrogen-assisted cold cracking (HACC) in the heat-affected zone (HAZ) or in the weld metal (WMHACC). Pipeline grades above X60, and up to and including X70, have been satisfactorily welded with cellulosic electrodes in various combinations; however, there have been widely documented problems, including serious instances of WMHACC. Australian experience, in particular, has stressed the advantages of using low strength (i.e., E6010) electrodes in the root pass in order to achieve the benefits of high toughness and reduce risk of WMHACC, and AS 2885.1 was specifically amended to delete the use of root bend tests so as to allow low strength electrodes to pass the procedure qualification test. Experience has shown that for pipeline grades up to around grade X60 (depending on the wall thickness), E6010 (E4110) electrodes can be used successfully whilst obtaining adequate strength matching between the weldment and the pipe. The welds made with E6010 electrodes also give good toughness, and have a low risk of WMHACC. Recent research has shown that EXX10 electrodes can suffer loss of coating moisture when they are exposed to the atmosphere, and that this loss of moisture can result in an increased likelihood of WMHACC due to increased transfer of alloying elements across the arc. Care needs to be taken to see that electrodes are supplied in packaging that prevents the loss of moisture, and that once the packaging is opened, the contents are discarded if not used on the same day.

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C3 STRENGTH MATCHING An important factor in the selection of girth welding consumables is the matching of pipe strength. In general, it is desirable that welds be stronger than the pipe they join so that, in the presence of a weld imperfection, if displacement controlled loads are experienced by the pipeline, the pipe will be plastically strained rather than the displacement being concentrated within the weld joint (see Clause 1.5.27). The subject of strength matching is extremely complex, and it is not possible to show in all circumstances that matching is achieved by means of simple tests.

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Recent research on the relatively thin-walled pipelines used in Australia has shown (by interpolation) that strength matching is achieved by the use of E6010 electrodes up to grade X60, and by combinations of E6010 and E8010 electrodes up to X65. The research has also shown that E6010 and E8010 combinations can undermatch X70 grade pipe, and that adequate strength matching in 5 mm wall thickness X80 can not be achieved with any existing cellulosic consumables. These observations are very much simplified and depend on a number of critical factors such as the actual strength of the pipe in the longitudinal direction, the test method used to assess the level of matching, and the pipe wall thickness. This experience is expected to be valid for circumstances in which the distribution of yield strength of the pipe is within the range of common Australian experience; however, the use of unexpectedly strong pipe will make it very difficult to achieve strength matching, especially in thin pipe in the higher grades. It is good practice, for a number of reasons, to limit the range of the transverse yield strength of the pipe, and attention is drawn to the option of specifying an upper limit to the yield strength of the pipe by utilizing the supplementary requirements of ANSI/API Spec 5L PSL 2. The method of measurement of the pipe yield strength is also important. Depending on the method of manufacture, the longitudinal strength of the pipe may be greater than or less than the transverse value, and the transverse value will be affected by the type of test piece, that is, whether a flattened strap test piece or a ring expansion test is employed. Whilst hardness testing and conventional joint tensile testing can provide useful information, which would help someone familiar with the research form a judgement on the degree of matching achieved, these tests cannot objectively determine whether matching is actually achieved. The notched tensile test, which was previously included in this Standard, has been found to be difficult to interpret and has been withdrawn pending further research. This change is accompanied by a return of the Tier 3 criteria to those in the 1995 edition of this Standard. Required levels of weld metal strength matching may be assessed using the wide plate test; however, it has been shown that they are still width sensitive up to around 300 mm or so and, at the time of preparing this Appendix, the only method that could be relied upon to represent the displacement controlled axial load case is the full section pipe tension test, which evaluates the entire joint circumference. C4 ELECTRODE QUALITY

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The performance of pipeline girth welds made with EXX10 electrodes depends heavily upon the design formulation and upon the manufacturing quality assurance of the electrodes. Unfortunately, however, the national specifications that are used for these electrodes do not meet the current needs of the pipeline industry. The specifications for the higher strength E7010, E8010 and E9010 low alloy steel electrodes AS/NZS 4857 and ANSI/AWS A5.5 are particularly inadequate. The purpose of this Appendix is to provide guidance on the desirable supplementary measures, which may be used to provide increased confidence in the integrity of the welds. The need for these supplementary measures is an important part of the pipeline project engineering process. In the past, the quality assurance processes in the procurement of welding consumables received too little attention; both in absolute terms and in comparison with pipe procurement. Over the last 20 years or so there have been major advances in the strength and the weldability of pipe steels. This has caused a situation where if welding problems are to occur they will most likely be in the weld metal, and this, combined with the limitations of current welding electrode Standards, has necessitated the development of this Appendix.

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C5 SUPPLEMENTARY RECOMMENDATIONS The following are recommended: (a)

A risk management approach be taken to this aspect of the design of the welding procedures. On this basis, large projects using high-strength pipe with, for example, significant areas of unstable ground, will justify greater effort in treating the risks of undermatching which has been referred to earlier in this Appendix.

(b)

On the basis of longstanding satisfactory experience, E6010 electrodes are suitable for use in circumstances where their application is warranted without supplementary requirements.

(c)

E7010-G, E8010-G, and E9010-G electrodes, without supplementary specification requirements, should not be used unless the risks identified are acceptable. Successful experience in the use of electrodes from a particular supplier in similar circumstances may be a suitable input to the risk assessment process.

(d)

In general, electrodes conforming to E7010-P1 and E8010-P1 (or equivalent) classifications are preferred, and if a higher strength electrode is required, then a specification for E9010-P1 should be negotiated with the supplier, even though such a classification does not currently exist in the Standards. NOTE: P1 Classifications incorporate Charpy V-notch fracture toughness requirements.

(e)

In addition to the use of P1 classification electrodes, it is recommended that all-weld metal limit of 0.17% carbon and a maximum IIW carbon equivalent (CE) be stipulated. The maximum CE values should not exceed the following: (i)

E7010 ...................................................................................................... 0.40.

(ii)

E8010 ...................................................................................................... 0.44.

(iii) E9010 ...................................................................................................... 0.46. These limits will help avoid the production of deposits of excessive strength and susceptibility to HACC. (f)

The electrodes should be manufactured under an approved quality assurance system and individual batches should be certified on test certificates.

(g)

For X70 pipelines less than 7 mm wall thickness, and for all X80 pipelines, special consideration should be given to girth weld strength matching. This may include the need for special tests such as full section pipe tension test.

(h)

Electrodes should be supplied in hermetically sealed metal containers and should be discarded if not used on the day the container is opened.

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C6 REFERENCES 1

Bilston K., Dietsch A., and Fletcher L. Performance requirements for onshore pipeline girth welds in Australia: A Discussion Paper, WTIA/APIA Panel 7 Research Seminar, Wollongong Oct 1995.

2

Barbaro F., Bilston K., Fletcher L., Kimber M., and Venton P. Research shows that X80 pipe can be economically and safely welded by conventional methods, The Pipeliner No 98, July 99.

3

Yurioka N. (Editor) Proceedings WTIA/APIA First International Conference on Weld Metal Hydrogen Cracking in Pipeline Girth Welds, CRC for Welded Structures March 99 Published Feb 00.

4

Bilston K. ‘Capabilities and limitations of cellulosic electrodes. A user’s perspective’ Ibid.

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Bowie G F and Barbaro F J., Assessment of workmanship defect acceptance levels in high strength thin walled pipeline girthwelds, International Conference on Pipeline Construction Technology, Wollongong, 4-5 March 2002.

6

Weaver R.J. and Ogborn J.S. Cellulosic covered electrode storage conditions – influence on weld properties. IBP_05. Rio Pipeline Conference and Expositions 2005. Instituto Brasileiro de Petrόleo Gás - IBP

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AS 2885.2—2007

APPENDIX D

GUIDANCE ON ‘GMAW’ WELDING CONSUMABLES FOR MECHANIZED PIPELINE GIRTH WELDS (Informative) The most commonly used consumables for GMA welding of pipeline steel grades below X80 is plain carbon manganese steel wire, which may have small additions of titanium and boron. These wires generally comply with the ANSI/AWS A5.18 classification E70S-6 and the nearest Australian equivalent is AS/NZS 2717.1 designation ES6xxW50. They are used with argon-based gas mixtures or CO 2 shielding. It is also reported that the same wires have been used successfully for fill passes on X80 pipeline steels but where overmatching yield strength is required, a nickel/molybdenum alloyed wire is preferred. It is, however, clear that within the broad classification of E70S-6 or ES6xxW50 there is scope for considerable variation in chemistry, both in the deliberate alloying additions, and in the level of residual elements. In some cases there may be deliberate but unreported additions of alloying element, and this may be indicated by the use of terms such as ‘microalloying’. This is of some concern in mechanized girth welding since small changes in alloying element levels can have a significant effect on strength and toughness, arc stability, slag formation, inter-pass cleaning, bead profile and hot cracking susceptibility. It should also be noted that the properties achieved vary with shielding gas and operating mode. In addition, consistent feedability and low contact resistance are very important in mechanized welding, and are influenced by the surface quality and coating thickness of the wire as well as its cast (diameter of a loose turn) and helix. The operator may also specify dehydrogenation baking of the wire at an appropriate stage of processing to achieve the lowest possible levels of hydrogen in weld metal. For all of the foregoing reasons operators of GMAW girth welding systems have chosen to test and qualify specific consumables by brand name rather than relying on Standard classifications. It is, therefore, important that the selected consumables be tested and qualified using a representative welding procedure and, once selected, the consumable be specified not only by standard designations but also by brand name (to avoid substitution).

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Regular batch testing of the consumable is recommended and the supplier should be advised that any substitution of a wire from a different manufacturing stream will require re-qualification.

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APPENDIX E

AVOIDANCE OF HYDROGEN ASSISTED COLD CRACKING (HACC) (Normative) E1 SCOPE This Appendix provides requirements for the selection and specification of welding procedures designed to avoid hydrogen assisted cold cracking (HACC) in the heat-affected zone (HAZHACC) or weld metal (WMHACC) in pipeline girth welds that are made with cellulosic electrodes. E2 BACKGROUND HACC, especially HAZHACC, is a widely known problem in welding technology, and a large body of research and practical technological literature exists on the subject. E3 HACC IN PIPELINE WELDING The problem of HACC in pipeline welding is unique, due to the following: (a)

Cellulosic electrodes are commonly employed, leading to very high levels of hydrogen in the weld metal of 30 ppm or more. These levels of hydrogen are never encountered in other safety critical large scale welded constructions.

(b)

Pipeline steels are amongst the strongest steels used for welded constructions, and the deliberate use of consumables having such high hydrogen levels is never encountered in other applications using high strength steels.

(c)

Pipeline girth welds are subjected to externally applied loads during welding as a result of lifting and lowering-off.

(d)

In high-strength pipe, the composition of the weld metal will, in order to achieve a strength level that matches the strength of the pipe, be substantially less weldable than the pipe. The pipe will be more leanly alloyed and hence more weldable than the weld metal because, and, unlike the weld metal, it has benefited from thermomechanical controlled processing (TMCP) during strip or plate rolling. (The same does not apply to fittings, and for this reason special care needs to be taken with the development of welding procedures for fittings.)

E4 WELD METAL HYDROGEN-ASSISTED COLD CRACKING (WMHACC)

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Unlike HAZHACC, there are no available methods for predicting the onset, and hence providing methods for avoidance of WMHACC. In the welding of modern high-strength pipelines WMHACC is the much more likely form of HACC. E5 DETECTION OF HACC WITH NDE In pipeline construction practice, the most common form of non-destructive examination (NDE) is radiography, which is not the most ideal tool for detection of HACC. High-quality X-radiography performed with fine-grained film and a single-wall single-image technique, with the primary beam normal to the longitudinal axis of the pipe, has a high probability of detecting cracks, but it is not as effective as ultrasonic testing. Other forms of radiography have a much lower probability of detecting cracks.

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AS 2885.2—2007

In other safety critical welding applications, the NDE is conducted at least 24 h after the completion of welding so as to ensure that delayed HACC will have taken place by the time the NDE is performed. In pipeline construction practice, considerable effort is expended to keep the NDE crew as close behind the welding crew as possible. Radiography is often completed in much less than 24 h. E6 THE EFFECT OF DELAY TIME In pipeline welding with cellulosic electrodes, when cracking does occur, it usually takes place within minutes of welding because the hydrogen concentration is already saturated, and the accumulation of hydrogen by diffusion (which is the rate-dependent process responsible for delayed cracking) is not required. The single most important factor that controls whether or not cracking will occur is the time delay between the root pass and the hot pass. Delays of more than 6 min between the completion of the root pass and the deposition of the hot pass greatly increase the risk of HACC occurring. The hot pass increases the weld throat thickness, reduces the notch effect strain concentration in the wagon track region, refines and tempers the microstructure, and most importantly raises the temperature of the weldment above the critical level for the onset of HACC and reduces the weld cooling rate to enhance hydrogen effusion. E7 THE EFFECT OF STRENGTH Another important practice that is adopted in pipeline welding is the deliberate use of low strength, often undermatching, electrodes for the root pass. This is a very effective method of reducing the risk of HACC by the use of lower strength more ductile weld metal that is less susceptible to the detrimental effects of hydrogen. E8 WELDING PROCEDURE QUALIFICATION Section 5 of this Standard requires the development and qualification of a welding procedure in order to demonstrate that the production welds made in accordance with that procedure, i.e., within the limits of the essential variables and the permitted changes to the essential variables will, amongst other things, be free from HACC.

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The welding procedures may be qualified by— (a)

testing;

(b)

documentation;

(c)

prequalification; or

(d)

supervision.

In any of these cases, because HACC is such a serious problem in view of its threat to the integrity of the pipeline, its potential systemic nature if it does occur, and the fact that it can not be detected during construction by NDE, it is of critical importance that it be designed out of the procedure, and this is a key part of procedure development and qualification. The risk of occurrence should be ‘remote’ under any welding condition that is within the envelope encompassed by the qualified procedure. This means that under the nominal (or mid-range) conditions there should be a substantial margin of safety. Again, using the risk assessment terminology of AS 2885.1, the likelihood of HACC under the nominal conditions of the procedure should be ‘improbable’. The means of achieving and, importantly, demonstrating this outcome is not simple. All of the tools that are required do not exist in a convenient form.

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There is no simple test that fully simulates the field welding situation. Whilst there are well-established guidelines for the avoidance of HAZHACC, there are no guidelines for the avoidance of WMHACC. The development of such guidelines is a key part of ongoing research programs. E9 RECOMMENDED METHODS WELDING PROCEDURES

FOR

‘DESIGNING-OUT’

HACC

FROM

E9.1 Restrictions These methods apply only to the following circumstances: (a)

Welding with conventional cellulosic electrode procedures.

(b)

Where the delay time between the start of the root pass and the start of the hot pass does not exceed 8 min.

(c)

Normal methods of onshore pipeline construction used in Australia.

(d)

The typical range of climatic conditions normally encountered in pipeline construction in Australia.

(e)

Welding of new pipe and fittings.

Other methods may be used for circumstances outside the restrictions; however such methods shall be fully documented, and shall be approved. E9.2 Welding of pipe E9.2.1 Normal lifts

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Where no more than 2 standard (up to 18 m) pipe lengths are lifted clear of the skids and where in all other respects the lifting and lowering off stresses are normal as for a largely level right of way without bends of any kind, the following applies: (a)

In pipe up to 14.5 mm wall thickness and DN 500, and up to and including X60 welded entirely with E6010 electrodes, the risk of HACC may be considered to be ‘remote’. The use of controlled heat input, preheat and other measures designed to reduce the risk of HACC is not required and the welding procedure qualification test weld (if required) need not simulate lifting and line-up stresses or other conditions expected to affect HACC.

(b)

In pipe up to 10 mm wall thickness and DN 500, up to and including X70, and with carbon equivalent (CE) values up to a limit of 0.40, weld with E6010 electrodes in the root and with electrodes up to E8010 specified in accordance with the recommendations of this Appendix, in the remaining passes, the risk of HACC may be considered to be ‘remote’ provided the electrode burn-off rate does not fall below the equivalent of 0.5 kJ/mm. The use of preheat is not required, and the welding procedure qualification test weld (if required) need not simulate lifting and line-up stresses or other conditions expected to affect HACC.

(c)

In circumstances outside those covered by Items (a) and (b) above, the risk of HACC may be considered ‘remote’ provided the welding procedure incorporates a minimum preheat and interpass temperature of 100°C.

(d)

Alternative methods of demonstrating that the risk of HACC is ‘remote’ may be used. These may be based on full-scale testing, involving simulation of the worst case condition that will be encountered in the field, or other methods such as correlations with laboratory tests such as Welding Institute of Canada tests. Such methods shall be fully documented, and shall be approved.

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E9.2.2 Extreme lifts For lifting conditions other than in Paragraph E9.2.1, a minimum preheat temperature of 100°C shall be used and the hot pass shall be completed prior to lifting or lowering off. The delay time between the start of the root pass and the start of the hot pass should not exceed 6 min. E9.3 Welding of fittings The development of welding procedures for fittings presents special problems. Firstly, for reasons referred to earlier, fittings of equivalent grade are likely to be less weldable than pipe. Secondly, the development of a welding procedure by testing, of necessity, results in the destruction of a fitting. And thirdly the methods of holding fittings for welding are quite different from that used for pipes. For fittings in material grades up to and including X52 or equivalent, the risk of HACC in the welding of fittings may be considered to be ‘remote’ providing low hydrogen welding procedures are used and the minimum preheat and interpass temperature is not less than that determined using WTIA Technical Note 1, or 100°C, whichever is higher. For fittings in higher grades, the carbon equivalent shall be known and unique procedures shall be developed and qualified. NOTE: Non-destructive examination of welds in fittings should be undertaken at least 24 h after the completion of welding.

E9.4 Repair welding

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The risk of HACC during repair welding is significant. Specific consideration should be given to the following: (a)

Repairs to the root bead from inside the pipe should be avoided due to the high risk of HACC in un-tempered low heat input welds and their HAZs.

(b)

Single pass cosmetic repairs to the capping pass should be avoided for the same reasons as in Item (a). If repairs to the capping pass are necessary, they shall be subjected to a qualified, documented, and approved procedure.

(c)

Low heat input stripper passes used to even out the extent of groove filling can constitute a risk of WMHACC, and should be avoided.

(d)

In general, the level of residual stress associated with repair welding will be higher than in the original welds, and the need for preheat is likely to be higher.

Whilst the use of low hydrogen electrodes is good practice for repair welding in order to reduce the risk of HACC, consideration needs to be given to the fact that when low hydrogen welding is undertaken the delay time before NDE should be at least 24 h. This is of course not a reason to avoid the use of low hydrogen welding methods. It just means that where a delay time of 24 h cannot be accommodated there needs to be a very high level of confidence that HACC has been designed out of the welding procedure and, in addition, that the procedure is adhered to.

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APPENDIX F

EXAMPLE OF WELD PROCEDURE SPECIFICATION FORM

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(Informative)

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121

REFERENCED PQRs: JOB NUMBER: CODE:

AS 2885.2—2007

WPS NUMBER:

00 PROJECT:

XYZ

XYZ-01

0

Standards Australia

SPECIFICATION:

AS 2885.2:200X

REVISION:

PROCESSES:

MMAW

MATERIALS

MATERIAL SPECIFICATION SMYS less than 413 MPa to SMYS greater than, or equal to, 413 MPa ELECTRICAL CHARACTERISTICS

MANUFACTURER

SMYS

MAX CE

DIAMETER RANGE

THICKNESS RANGE (DTT)

N/A to

0.76

Fill 3

1

W007

MMAW

6G

Dwn

F5

45

DCEP

170 - 188

28 - 30

89 - 127

>1.65

4

1

W007

MMAW

6G

Dwn

F5

DCEP

160 - 170

29 - 32

112 - 166

5

1

W007

MMAW

6G

Dwn

F5

DCEP

155 - 165

27 - 29

165 - 200

2.50 3.45 1.85 2.49 1.33 1.66

Cap 6

1

W007

MMAW

6G

Dwn

F5

DCEP

150 - 155

29 - 31

204 - 235

>0.78

7

1

W007

MMAW

6G

Dwn

F5

DCEP

140 - 145

28 - 30

247 - 275

8

1

W007

MMAW

6G

Dwn

F5

DCEP

145 - 155

27 - 31

283 - 341

1.17 1.41 0.86 1.06 0.85 0.92

Prepared by:

 Standards Australia

Approved by:

132

113

>1.14 >0.97

>0.64 >0.55

Date:

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