UNI-EN 12732 (2005)

NORMAEUROPEA

Pagina IUNI EN 12732:2005

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UNIEnte Nazionale Italianodi Unificazione

Via Battistotti Sassi, 11B20133 Milano, Italia

UNI EN 12732

FEBBRAIO 2005

Trasporto e distribuzione di gas

Saldatura delle tubazioni di acciaio

Requisiti funzionali

Gas supply systems

Welding steel pipework

Functional requirements

La norma contiene i requisiti per la produzione e il controllo digiunti saldati per l’installazione e la modifica di tubazioni e canaliz-zazioni d’acciaio terrestri utilizzate nei sistemi per il trasporto e ladistribuzione di gas, ivi comprese le tubazioni in servizio per tuttele gamme di pressione per il trasporto di gas naturale trattato, nontossico e non corrosivo in conformità alla ISO 13686 quando:

-

gli elementi delle tubazioni sono realizzati in acciaio al carbonionon legato o leggermente legato;

- la tubazione non è situata in aree commerciali o industrialicome parte integrante del processo industriale su tali aree, adeccezione delle tubazioni e canalizzazioni utilizzate per il rifor-nimento di queste ultime;

- la tubazione non è ubicata in impianti per uso domesticosecondo la UNI EN 1775;

- la temperatura di progetto del sistema è compresa tra -40 °C e

120 °C.

TTT EEE SSS TTT OOO III NNN GGG LLL EEE SSS EEE

La presente norma è la versione ufficiale in lingua inglese della

norma europea EN 12732 (edizione aprile 2000).

ICS 25.160.40

© UNI Pagina IIUNI EN 12732:2005

Le norme UNI sono elaborate cercando di tenere conto dei punti di vista di tutte le partiinteressate e di conciliare ogni aspetto conflittuale, per rappresentare il reale statodell’arte della materia ed il necessario grado di consenso.Chiunque ritenesse, a seguito dell’applicazione di questa norma, di poter fornire sug-gerimenti per un suo miglioramento o per un suo adeguamento ad uno stato dell’artein evoluzione è pregato di inviare i propri contributi all’UNI, Ente Nazionale Italiano diUnificazione, che li terrà in considerazione per l’eventuale revisione della norma stessa.

Le norme UNI sono revisionate, quando necessario, con la pubblicazione di nuove edizioni odi aggiornamenti. È importante pertanto che gli utilizzatori delle stesse si accertino di essere in possessodell’ultima edizione e degli eventuali aggiornamenti. Si invitano inoltre gli utilizzatori a verificare l’esistenza di norme UNI corrispondenti allenorme EN o ISO ove citate nei riferimenti normativi.

PREMESSA NAZIONALE

La presente norma costituisce il recepimento, in lingua inglese, del-la norma europea EN 12732 (edizione aprile 2000), che assume co-sì lo status di norma nazionale italiana.

La presente norma è stata elaborata sotto la competenza dell’entefederato all’UNI

CIG - Comitato Italiano Gas

La presente norma è stata ratificata dal Presidente dell’UNI, condelibera del 18 gennaio 2005.

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 12732

April 2000

ICS 25.160.40

English version

Gas supply systems - Welding steel pipework - Functionalrequirements

Systèmes d'alimentation en gaz - Soudage des tuyauteriesen acier - Prescriptions fonctionnelles

Gasversorgungssysteme - Schweißen von Rohrleitungenaus Stahl - Funktionale Anforderungen

This European Standard was approved by CEN on 16 August 1999.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.

CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATIONC O M I T É E U R O P É E N D E N O R M A LI S A T I O NEUR OP ÄIS C HES KOM ITEE FÜR NOR M UNG

Central Secretariat: rue de Stassart, 36 B-1050 Brussels

© 2000 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.

Ref. No. EN 12732:2000 E

EN 12732:2000

Contents Page

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Definitions and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4 Quality system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1 Welding contractors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.2 Welders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.3 Welding supervisory/co-ordination personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.4 Testing personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5 Welding consumables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6 Production welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6.1 General requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116.2 Joint preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126.3 Preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.4 Tacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.5 Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.6 Actions after welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.7 Repair of weld defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7 Special procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.1 Attachment of structural parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147.2 Attachment of cathodic protection connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147.3 Hot tapping and other welding work on pressurized pipelines and systems . . . . . . . . . . . . . . 14

8 Inspection of the weld joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

8.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158.2 Scope of inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158.3 Non-destructive examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168.4 Time of inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188.5 Acceptance criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188.6 Recording of test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

9 Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

9.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189.2 Archiving requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

10 Specific requirements for gas supply systems up to and including 16 bar MOP (distribution) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

10.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1810.2 Welders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910.3 Welding supervisory personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910.4 Production welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1910.5 Acceptance requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2010.6 Requirements for records and documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

EN 12732:2000

11 Specific requirements for gas supply systems greater than 16 bar MOP (transmission) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

11.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2011.2 Welders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2011.3 Welding supervisory personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2011.4 Qualification of welding procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

11.5 Production welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2211.6 Destructive testing of production welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2311.7 Acceptance requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2311.8 Requirements for records and documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

12 Specific requirements for metering, regulating and compressor stations . . . . . . . . . . . . 25

12.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2512.2 Specific requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Annex A (informative) Qualification for pipeline welders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Annex B (informative) Testing of the base material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Annex C (informative) Wall thickness compensation/Design examples . . . . . . . . . . . . . . . . . . . . . . 30

Annex D (informative) Critical aspects for hot-tap welding or welding on gas-pressurized pipelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Annex E (informative) Visual inspection of joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Annex F (informative) Manual ultrasonic testing of weld joints for wall thicknesses between approximately 6 mm and 10 mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Annex G (informative) Acceptance criteria recommendations for on-site production welds . . . . . . 38

Annex H (informative) Recommendations for brazing and aluminothermic welding of anodic bonding leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Annex I (informative) Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

EN 12732:2000

Foreword

This European Standard has been prepared by Technical Committee CEN/TC 234 "Gas supply", thesecretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publicationof an identical text or by endorsement, at the latest by October 2000, and conflicting nationalstandards shall be withdrawn at the latest by October 2000.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of thefollowing countries are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg,Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

There is a complete suite of functional standards prepared by CEN/TC 234 „Gas supply“ to coverall parts of the gas supply system from the input of gas to the transmission system up to theinlet connection of the gas appliances, whether for domestic, commercial or industrialpurposes.

In preparing this standard a basic understanding of gas supply by the user has been assumed.

Gas supply systems are complex and the importance on safety of their construction and use has ledto the development of very detailed codes of practice and operating manuals in the membercountries. These detailed statements embrace recognised standards of gas engineering and thespecific requirements imposed by the legal structures of the member countries.

CEN/TC 234 will continue its work updating this Standard to the latest developments at regularintervals.

This European Standard has been prepared under mandate M/017 given to CEN by the Commission ofthe European Communities and the European Free Trade Association.

1 Scope

This European Standard contains requirements for the production and testing of weld joints forthe installation and modification of onshore steel pipelines and pipework used in gas supplysystems, including in-service pipelines, for all pressure ranges for the carriage of processed,non-toxic and non-corrosive natural gas according to ISO 13686, where

- the pipeline elements are made of unalloyed or low-alloyed carbon steel;

- the pipeline is not located within commercial or industrial premises as integral part of theindustrial process on those premises except for any pipelines and facilities supplying suchpremises;

- the pipework is not located within household installations according to EN 1775:1998;

- the design temperature of the system is between -40 °C and 120 °C inclusive.

With respect to production and testing of welds, this European Standard refers to basicstandards drafted by CEN/TC 121 and CEN/TC 138 as they exist up to the date of issue of thisstandard.

This standard is not applicable to welds produced prior to the publication of this Europeanstandard.

Clauses 4 to 9 describe general requirements which relate to all areas of application mentioned.

The following clauses contain specific requirements:

Clause 10: Supply systems for a maximum operating pressure up to and including 16 bar(distribution)

Clause 11: Supply systems for a maximum operating pressure greater than 16 bar (transmission)

EN 12732:2000

Clause 12: Metering, regulating and compressor stations

Table 1 assigns the application areas to quality requirement categories as a function of theworking pressure and pipe materials used.

Table 1: Allocation to quality requirement categories

Quality requirement Area of activity applies tocategory

A Pressure range and base material � 100 mbar

Examples of use

Group 1 according to EN 288-3:1992R � 360 N/mmt 0,5

2

Mains and service pipes in gasdistribution systems

B Pressure range and base material > 100 mbar � 5 bar

Examples of use


2

Mains and service pipes in gasdistribution systems, pipeworkin stations

C Pressure range and base material > 5 bar � 16 bar

Examples of use


2

Pipelines including pipework instations and gas distributionsystems

D Pressure range or base material > 16 bar

Examples of use

*

Group 1 to 3 according to EN 288-3:1992

Pipelines including pipework instations and gas transmissionsystems

Note:R specified minimum yield strength according to EN 10208-2:1996.t 0,5

Pipelines having hoop stresses at design pressure up to 30 % of specified minimum*

yield strength and operated at a pressure up to 24 bar can be allocated to qualityrequirement category C by the pipeline operator.

Additional requirements may be specified when, for example

- the strain on pipelines and systems;

- the materials;

- the line routing;

- the design or the welding technique

are considered critical.

This European Standard specifies common basic principles for gas supply systems. Users of thisEuropean Standard should be aware that there can exist more detailed national standards and/or

EN 12732:2000

codes of practice in the CEN member countries.

This European Standard is intended to be applied in association with these national standardsand/or codes of practice setting out the above-mentioned basic principles.

In the event of conflicts in terms of more restrictive requirements in nationallegislation/regulation with the requirements of this standard, the nationallegislation/regulation shall take precedence.

2 Normative references

This European Standard incorporates by dated or undated reference, provisions from otherpublications. These normative references are cited at the appropriate places in the text and thepublications are listed hereafter. For dated references, subsequent amendments to or revisionsof any of these publications apply to this European Standard only when incorporated in it byamendment or revision. For undated references the latest edition of the publication referred toapplies.

EN 287-1:1997 Approval testing of welders - Fusion welding - Part 1: Steels

EN 288-2:1992 Specification and approval of welding procedures for metallic materials - Part 2: Welding procedure specification for arc welding

EN 288-3:1992 Specification and approval of welding procedures for metallic materials - Part 3: Welding procedure tests for the arc welding of steels

EN 288-5:1994 Specification and approval of welding procedures for metallic materials - Part 5: Approval by using approved welding consumables for arc welding

EN 288-6:1994 Specification and approval of welding procedures for metallic materials - Part 6: Approval related to previous experience

EN 288-7:1995 Specification and approval of welding procedures for metallic materials - Part 7: Approval by a standard welding procedure for arc welding

EN 288-8:1995 Specification and approval of welding procedures for metallic materials - Part 8: Approval by a pre-production welding test

prEN 288-9 Specification and approval of welding procedures for metallic materials - Part 9: Welding procedure test for on land and offshore site butt welding oftransmission pipelines

EN 439:1994 Welding consumables - Shielding gases for arc welding and cutting

EN 440:1994 Welding consumables - Wire electrodes and deposits for gas-shielded metal arcwelding of non-alloy and fine-grain steels - Classification

EN 473:1993 Qualification and certification of NDT personnel. General principles

EN 499:1994 Welding consumables - Covered electrodes for manual metal arc welding of non-alloy and fine-grain steels - Classification

EN 571-1:1997 Non-destructive testing - Penetrant testing - Part 1: General principles

EN 583-1 Non-destructive testing - Ultrasonic examination - Part 1: General principles

EN 719:1994 Welding coordination - Tasks and responsibilities

EN 729-1:1994 Quality requirements for welding - Fusion welding of metallic materials - Part 1: Guidelines for selection und use

EN 729-2:1994 Quality requirements for welding - Fusion welding of metallic materials - Part 2: Comprehensive quality requirements

EN 729-3:1994 Quality requirements for welding - Fusion welding of metallic materials -

EN 12732:2000

Part 3: Standard quality requirements

EN 729-4:1994 Quality requirements for welding - Fusion welding of metallic materials - Part 4: Elementary quality requirements

EN 756:1995 Welding consumables - Wire electrodes and wire-flux combinations forsubmerged arc welding of non-alloy and fine grain steels - Classification

EN 757:1997 Welding consumables - Covered electrodes for manual metal arc-welding of highstrength steels - Classification

EN 758:1997 Welding consumables - Tubular cored electrodes for metal arc welding with orwithout a gas shield of non-alloy and fine grain steels - Classification

EN 760:1996 Welding consumables - Fluxes for submerged arc welding - Classification

EN 970:1997 Non-destructive examination of fusion welds - Visual examination

EN 1290:1998 Non-destructive examination of welds - Magnetic particle examination of welds

EN 1418:1997 Welding personnel - Approval testing of welding operators for fusion weldingand resistance weld setters for fully mechanized and automatic welding ofmetallic materials

EN 1435:1997 Non-destructive examination of welds - Radiographic examination of weldedjoints

EN 1668:1997 Welding consumables - Rods, wires and deposits for tungsten inert gas weldingof non alloy and fine grain steels - Classification

prEN 1708-1 Welding - Basic weld joint details in steel - Part 1: Pressurized components

EN 1714:1997 Non-destructive examination of welds - Ultrasonic examination of weldedjoints

EN 1775:1998 Gas supply - Gas pipework for buildings - Maximum operating pressure � 5 bar -Functional recommendations

EN 10002-1:1990 Metallic materials - Tensile testing - Part 1: Method of test

EN 10204:1995 Metallic products - Types of inspection documents

EN 10208-1:1997 Steel pipes for pipelines for combustible fluids - Technical deliveryconditions - Part 1: Pipes of requirement class A

EN 10208-2:1996 Steel pipes for pipelines for combustible fluids - Technical deliveryconditions - Part 2: Pipes of requirement class B

EN 24063:1992 Welding, brazing, soldering and braze-welding of metals - Nomenclature ofprocesses and reference numbers for symbolic representation on drawings (ISO 4063:1990)

EN 25817:1992 Arc-welded joints in steel - Guidance on quality levels for imperfections(ISO 5817:1992)

EN 26520:1991 Classification of imperfections in metallic fusion welds with explanations(ISO 6520:1982)

EN 27963:1992 Welds in steel - Calibration block No. 2 for ultrasonic examination of welds(ISO 7963:1985)

EN 29692:1994 Metal-arc welding with covered electrode, gas-shielded metal-arc welding andgas welding - Joint preparations for steel (ISO 9692:1992)

EN 45001:1989 General criteria for the operation of testing laboratories

EN 12732:2000

ISO 13686 Natural gas - Quality designation

3 Definitions and abbreviations

For the purposes of this standard, the following definitions apply. Symbols used in formulae are defined where they occur.

3.1 design temperature (DT): The temperature on which the design calculations are based.

3.2 gas: The gaseous fuel which is in a gaseous state at a temperature of 15 °C under atmosphericpressure (1,013 25 bar absolute).

3.3 gas distribution system: The pipeline system including piping above and below ground and allother equipment necessary to supply the gas to the consumer.

3.4 gas distributor: The private or public organization authorized to distribute gas toconsumers through a gas distribution system.

3.5 gas transmission: The activity intended to convey gas from one place to another throughpipelines in order to supply gas to distribution systems or to industrial consumers.

3.6 installation: Equipment and facilities for the extraction, production, chemical treatment,measurement, control, storage or offtake of the transported gas.

3.7 maximum operating pressure (MOP): The maximum pressure at which a system can be operatedcontinuously under normal conditions.

Note: normal conditions are: no fault in any device or stream.

3.8 national requirements: Requirements following from national legislation or more detailedor stringent national standards

3.9 onshore pipeline: A buried and/or above ground pipeline including those sections laid in oracross inland lakes or water courses.

3.10 pipeline: A system of pipework with all associated equipment and stations up to the point ofdelivery. This pipework is mainly below ground but also includes above ground parts.

3.11 pipeline components: The elements from which a pipeline is constructed. The following aredistinct pipeline elements:

- pipe including cold-formed bends;

- fittings

EXAMPLE 1: reducers, tees, factory-made elbows and bends, flanges, caps, welding stubs, mechanical joints.

- fabrications, manufactured from elements referred above;

EXAMPLE 2: manifolds, slug catchers, pig launching/receiving stations, metering and controlruns.

- equipment;

EXAMPLE 3: valves, expansion joints, insulating joints, pressure regulators, pumps, compressors.

- pressure vessels.

3.12 pipeline operator: The private or public organization authorized to design, construct,and/or operate and maintain the gas supply system.

3.13 pipework: An assembly of pipes and fittings.

EN 12732:2000

3.14 pressure: The gauge pressure of the fluid inside the system, measured in staticconditions.

3.15 station: A plant or facility for the operation and/or processing of gas supply systems.

3.16 test pressure (TP): The pressure to which the gas supply system is subjected, to ensurethat it can operate safely.

4 Quality system

If required by the pipeline operator, a quality system shall be applied to pipeline welding. Aset of recommended quality requirements according to EN 729 is provided in Table 2, whichspecifies the requirements of EN 729 for the different categories as defined in Table 1.

Table 2: Recommended quality requirements

Requirement relating to:Quality requirement category in

accordance with Table 1

A B C D

Quality system according to:

EN 729-1:1994 and EN 729-2:1994(complete) + + * *EN 729-1:1994 and EN 729-3:1994 (standard) + + * *EN 729-1:1994 and EN 729-4:1994 (elementary) * * - -

Welding coordination personnel:

� according to EN 719:1994: welding engineer + + + *welding technician1)

+ + * -welding specialist1)

+ * * -� Foreman welder with several years technical experience * * - -

Testing personnel according to EN 473:1993 * * * *

Welding procedure specification (WPS):

according to EN 288-2:1992 (except gas welding, procedure no. 311) * * * *

Approval of welding procedures according to one of the following standards:

EN 288-3:1992 (welding procedure test) + + * *EN 288-5:1994 (using approved welding consumables) * * - -EN 288-6:1994 (previous experience) * - - -EN 288-7:1995 (standard welding procedures)

1)

+ + * *EN 288-8:1995 (pre-production welding test) + * * *prEN 288-9 (welding procedure test for site welding) + + + *

1) This may be applicable in category D for small projects or for materials with R � 360 N/mm².t 0,5

Explanation: * recommended+ optional - not recommended

EN 12732:2000

taking into account any specific property requirements1)

4.1 Welding contractors

If required by the pipeline operator, contractors shall demonstrate their ability to performthe work. Reference can be made to EN 729.

4.2 Welders

All welders shall be qualified for the work they are required to undertake.

The qualification should be carried out in accordance with an appropriate specification (seeclauses 10, 11 and 12).

The pipeline operator may accept welders provided it can be demonstrated that they have producedwelds of the required quality within the essential variables of the welding procedure.

4.3 Welding supervisory/co-ordination personnel

Welding tasks and responsibilities for welding shall be assigned to personnel with theappropriate experience and technical knowledge. Where a quality system is required, thesepersonnel should be qualified to EN 719:1994.

4.4 Testing personnel

Destructive testing and non-destructive examination personnel shall be employed either by thepipeline contractor or by the pipeline operator or by an independent testing company. Allcompanies providing such personnel should be certified. All non-destructive examinationpersonnel shall be qualified for the duties they are to perform in accordance with EN 473:1993 orskill recognition by the pipeline operator.

5 Welding consumables

Welding consumables shall be in accordance with:

Shielded metal arc welding (prodedure no. 111) : EN 499:1994 and EN 757:1997Gas metal arc welding (procedures nos. 135, 141) : EN 440:1994 and EN 1668:1997Flux-cored arc welding (procedures nos. 114, 136) : EN 758:1997Shielding gases : EN 439:1994Submerged arc welding (prodedure no. 12) : EN 756:1995Fluxes for submerged arc welding (prodedure no. 12) : EN 760:1996

The numbering of the procedures given in brackets is in accordance with EN 24063:1992.

All filler materials shall be certified as conforming to the relevant European Standard.Batch testing of the filler materials can be required by the pipeline operator. The certificatesshall be in accordance with EN 10204:1995, type 3.1.B. The chemical composition of the depositedweld metal shall be compatible with the parent metal.1)

Unless otherwise agreed, matching weld metal for girth welds shall be required. For the1)

selection of consumables, the use of Table 3 is recommended.

After filler material has been removed from its original package, it shall be protected orstored in accordance with the manufacturer's requirements, so that its characteristics orwelding properties are not affected.

EN 12732:2000

Table 3: Matching filler material requirements

Steel specification Filler material requirementsto EN 10208-1:1997 and to EN 440:1994/EN 499:1994/EN 757:1997

EN 10208-2:1996**

Designatio Designation n

R R R R KVt 0,5

N/mm N/mm N/mm N/mm J2

m

2

t 0,5

orRp 0,2

2

m

2

L 210 210 335 - 475 E35 355 440 - 570

L 245 245 - 440 415 E35 355 440 - 570

L 290 290 - 440 415 E35 355 440 - 570 47/32

L 360 360 - 510 460 E42 420 500 - 640

L 415 415 - 565 520 E46 460 530 - 680*

L 450 450 - 570 535 E46 460 530 - 680*

L 485 485 - 605 570 E50 500 560 - 720*

L 555 555 - 675 625 E55 550 610 - 780*

E62 620 690 - 890

NOTES:

* For wall thicknesses > 8 mm a lower strength consumable can be used for the root andhot pass.

** Fitting materials are to be specified in accordance with the appropriate EN standard.

R Specified minimum yield strength measured in N/mm .t 0,52

R Tensile strength according to EN 10208-2:1996 measured in N/mm .m2

R 0,2 % proof strength according to EN 10002-1:1991 measured in N/mm .p 0,22

KV Impact test value (Charpy-V method) obtained for full size specimen(average/individual) measured in Joule.

6 Production welding

6.1 General requirements

All welding shall comply with the approved welding procedure specification.

6.1.1 Working area

The working space shall enable adequate access to the work area in order to provide a safeenvironment and to allow satisfactory production and testing of a weld joint.

6.1.2 Layout of weld joints

Weld joints, in particular tie-ins, shall be arranged and designed in a way suited to the plannedwelding and testing technique. The placement of tie-in welds is particularly important.

6.1.3 Types of weld joints

Unless otherwise agreed, pipes and pipeline fittings shall be connected using butt-weldedjoints.

EN 12732:2000

6.1.4 Joint edge preparation

Joint edge preparations shall comply with the appropriate EN standards and the approved weldingprocedure. Appropriate EN standards include prEN 1708-1 and EN 29692:1994. The choice of jointconfiguration shall take into account the welding technique, the welding position and theaccessibility of the joint.

6.1.5 Weld spacing

Weld spacing shall be sufficient to ensure the integrity of the joint.

6.1.6 Different wall thicknesses

When pipes of different wall thicknesses have to be joined together, special precautions shallbe taken to avoid stress concentration and weld defects.

When butt welding pipework of different wall thicknesses has to be performed, 6.2.2 below and/orprEN 1708-1 shall apply. Annex C of this Standard should also be observed.

6.1.7 Pipe branches and nozzles

Forged fittings are preferred. Weld-on branches and nozzles are allowed.

6.1.8 Laminations

Additional precautions can be required where welding is performed in the area of laminations.

A recommended procedure for checking for laminations is given in Annex B.

6.1.9 Butt welded cross joints

Unless otherwise agreed, butt welded cross joints shall be avoided.

6.2 Joint preparation

6.2.1 Pipe end preparation

To ensure that the required weld quality is achieved, all necessary details concerning the jointpreparation have to be laid down in the welding procedure specification.

6.2.2 Alignment of the joints

Alignment clamps shall be used where possible; the details and how they are to be used shall beincluded in the welding procedure specification.

Root misalignment is acceptable as far as it is not affecting the integrity of the joint. Forrecommendations see Annex G.

Misalignment of pipes and pipelines made of steel grades with a minimum specified yield strength R less than or equal to 360 N/mm which is outside the tolerance range of the tables given int 0,5

2

Annex G may be compensated for by deformation, if agreed by the pipeline operator, by the use ofspecial equipment or by transition pieces. The heat-treatment condition of the material shallbe taken into account.

NOTE: The strength of thermomechanically treated as well as quenched and termpered steelsis, in some cases, permanently reduced by heating to temperatures above 580 �C.

EN 12732:2000

Root misalignment of pipes and pipelines of different wall thicknesses and made of steel gradeswith a specified minimum yield strength R greater than 360 N/mm which is outside thet 0,5

2

tolerance range of the tables given in Annex G shall be compensated for by using transitionpieces.

During correction of excessive root misalignment, measures shall be taken to avoid defects.Examples of permissible weld configurations are given in Annex C.

6.3 Preheating

Preheating shall be applied in accordance with the welding procedure specification.

6.4 Tacking

Whenever tack welds are used, they shall be made using the welding procedure designed for theroot pass. They shall be distributed equally around the circumference.

The tacks shall be free from cracks. Cracked tacks shall not be welded over, and shall be ground out and rewelded.

6.5 Welding

Precautions shall be taken to:

- minimize hydrogen pick-up in the work, in particular for steels which are sensitive tocold cracking;

- avoid condensation;

- avoid air movements in the pipe;

- avoid uncontrolled electrical current;

- minimize magnetic effects;

- avoid cold cracking;

- avoid arc strikes.

6.6 Actions after welding

After the weld is completed, weld spatter shall be removed. The weld surface shall be cleaned ofslag. The cooling process shall not be accelerated beyond the rate specified in the weldingprocedure specification.

Where air temperatures are below 5 �C and/or poor climatic conditions like wind or rain prevail,or if the pipeline operator requires it, the weld joint shall be protected against excessivelyrapid cooling.

Stress-relief heat treatment may be necessary.

6.7 Repair of weld defects

Weld joints which do not meet the specified requirements shall be repaired or cut out. On eachweld joint which requires repair, the faulty area shall be clearly marked. The marking shall notbe removed until the defect has been repaired and the repair work has been inspected. If morethan 20 % of the total weld exhibits defects requiring repair, or if several defective weldsections amount to this length overall, the weld joint in question shall be cut out and reweldedunless otherwise agreed by the pipeline operator.

EN 12732:2000

Weld joints with cracks shall be completely cut out. However, in special cases, and whereapproved by the pipeline operator, cracks may be repaired provided the cause of the crack hasbeen established beyond doubt and provided it is confirmed that the fault has been correctlyidentified.

Repairs shall be retested non-destructively using suitable techniques.

If non destructive testing of a repair reveals that the area still has unacceptable indications, the weld shall be cut out and rewelded unless otherwise agreed by the pipelineoperator.

7 Special procedures

Before special procedures as given below are carried out, the type and scope of testing of theweld joint shall be specified. The scope of the testing shall be in accordance with 8.2. Thetesting technique used will depend on the type and dimension of the weld pieces.

7.1 Attachment of structural parts

Structural parts shall be attached using a continuous weld. Intermittent welds shall not beused.

When welding structural parts onto components made of steel grades with specified minimum yieldstrength greater than 360 N/mm , special measures shall be employed which take account of the2

material characteristics.

EXAMPLE: buttering with low-yield/low-hydrogen electrodes.

These precautions shall be specified in the welding procedure specification.

7.2 Attachment of cathodic protection connections

Electrical bonds to the pipe surface must be made with a welding or brazing method which does notalter the integrity of the metal. It shall be demonstrated by a performance test that themetallurgical structure is not adversely affected.

To qualify for making cathodic protection connections, the operator's skill shall be testedunder site conditions before work begins.

When cable connections are made to the pipeline, the adhesion of the weld shall be verified.

Recommendations for brazing and aluminothermic welding of anodic bonding leads are given inAnnex H.

7.3 Hot tapping and other welding work on pressurized pipelines and systems

All hot-tap welding procedures shall include the following additional requirements:

Hot-tap welding shall only be carried out after sufficient research and development to ensurethe safety of the operation and the correct mechanical properties of the weld.

Prior to the execution of welding work on pressurized pipelines and systems, the pipelineoperator shall establish whether the design, the material and the construction condition of thepipeline allows welding under operating pressure. Critical aspects for hot-tap welding shall beincluded in the welding procedure specification and shall be subject to approval by the pipelineoperator. A list of critical aspects is given in Annex D for information.

Welding sleeves and split-tees greater than DN 50 nominal size for use on pipelines made of steelgrades with specified minimum yield strength greater than 360 N/mm shall be of the split full-2

encirclement type or shall incorporate additional local reinforcement.

EN 12732:2000

The longitudinal seam weld of a split attachment shall not be allowed to impinge on the pipe wallof the pressurized pipe. Where the attachments are of steel grades with specified minimum yieldstrength greater than 360 N/mm or are designed so that longitudinal contraction stresses can2

cause deformation, the first circumferential fillet weld shall be completed before the secondis started. The cooling rate shall not be increased. Where tacks for installation purposes arenecessary in the area of the second circumferential weld these shall be ground out completely.

8 Inspection of the weld joint

8.1 General

Weld quality shall be ensured by inspection of the welds using destructive tests and/or non-destructive examination. The results of these tests shall be documented. Non-destructiveexamination shall be carried out in accordance with approved procedures and destructive testingshall be as for the original welding procedure, i.e. EN 288-3:1992 or prEN 288-9.

8.2 Scope of inspection

The inspection shall comprise inspection during welding, final visual inspection, non-destructive examination and destructive testing.

The minimum extent of non-destructive examination in respect of the quality requirementcategory and the type/position of the weld joint is given in Table 4.

The pipeline operator shall select which welds are to be tested.

Where less than 100 % non-destructive examination is performed and the quality of the weld jointdoes not meet the requirements, further welds shall be examined to determine the extent of theproblem. The cause of the fault shall be eliminated. Except when otherwise agreed, two furtherwelds shall be inspected for each rejected weld.

Table 4: Minimum extent of non-destructive examination

Quality Radiographyrequirement or Surfacecategory in Type/position of the weld joint ultrasonic crackaccordance examination testwith Table 1 (see note 1)

Visualexaminationby weldingsupervisor

A Circumferential welds, branches, See note 2 See note 2nozzles and fillet welds; longitudinal See note 3seams

Unconcealed pipe spans; pipelines on 100 % See note 4bridges, pipeline sections crossing

railways, navigable waterways or landingstrips/runways

B Circumferential welds See note 2 See note 2Branches, nozzles and fillet welds See note 2 See

note 2Longitudinal seams 100 % 10 %

Unconcealed pipe spans; pipelines on 100 % See note 4bridges, pipeline sections crossing

railways, major roads and motorways,navigable waterways or landing

strips/runwaysC Circumferential welds 20 % 10 %

Branches, nozzles, fillet welds 100 % 10 %Longitudinal seams 100 % 100 %

Weld joints not included in the pressure 100 % 100 %test

Unconcealed pipe spans; pipelines on 100 % 100 %bridges, pipeline sections crossing

railways, major roads and motorways,navigable waterways or landing

strips/runwayscontinued

EN 12732:2000

Table 4: Minimum extent of non-destructive examination (continued)

Quality Radiographyrequirement or Surfacecategory in Type/position of the weld joint ultrasonic crackaccordance examination testwith Table 1 (see note 1)

Visualexaminationby weldingsupervisor

D Circumferential welds 100 % 20 %Branches, nozzles, fillet welds 100 % (See note 7) 20 %

(see note 5)Longitudinal seams 100 % 100 %

SweepoletsWeld joints not included in the 100 % 100 %

pressure test (see note 6)If pipelines/units are laid or 100 % 100 %

installed in built-up areasUnconcealed pipe spans; pipelines 100 % 100 %

on bridges, pipeline sectionscrossing railways, major roads andmotorways, navigable waterways or

landing strips/runwaysNote 1: The proportion of both techniques shall be agreed.

Note 2: Representative random sample on the basis of the total number of weld joints made by a welder during the course of one year.

Note 3: One destructive test of field weld per year by means of tensile and/or bending test for welders qualified only for gas welding (procedure no. 311) or only for fillet welds.

Note 4: The pipeline operator shall specify the extent of non-destructive examination taking into account the design conditions, for example:

- external loads in addition to internal pressure;- supports;- expansion due to temperature.

Note 5: Where welds with incomplete penetration are used, the pipeline operator can require 100 %.

Note 6: Seams shall be tested 100 % by two different inspection techniques.

Note 7: For branches and nozzles, consideration should be given by the pipeline operator to these methods.

Concluded

8.3 Non-destructive examination

The method or combination of methods for visual and non-destructive examination of the weldsshall be specified by the pipeline operator. Prior to commencement of welding, the non-destructive examination procedures shall be submitted to the pipeline operator for approval.In special cases, one inspection test method may be replaced by another.

Other forms of non-destructive examination can be required, depending on the material used, thedesign and/or the welding technique.

Visual examination of welds should be carried out in accordance with EN 970:1997. Supplementaryrecommendations are given in Annex E.

Non-destructive examination proceduresaccording to 8.3

Application

Supply systems MOP < 16 barQuality requirement cat. A, B, C

Supply systems MOP > 16 barQuality requirement cat. D

StationsQuality requirement cat.

A, B, C, D

Visualexamination

Magneticparticle

examination

Dyepenetrant

examination

Radiographicexamination

Ultrasonicexamination

Procedure:EN 970:1997

Annex E


Procedure:EN 571-1:1997


EN 1435:1997

Procedure:prEN 583-1

EN 1714:1997Annex F

Criteria:Annex EAnnex G

Criteria:Annex G

Criteria:Annex G

Criteria:Annex G

Criteria:Annex GTable G.3

Page 17EN 12732:2000

Radiographic examination shall be carried out in accordance with EN 1435:1997. If not otherwiseagreed by the pipeline operator, the image quality class shall be class A for categories Athrough C and class B for category D. The test laboratory contracted for radiographic workshould be accredited to EN 45001:1989.

Ultrasonic examination shall be carried out in accordance with EN 583-1 and EN 1714:1997.Supplementary recommendations are given in Annex F.

In procedures nos. 114, 135 and 136 in accordance with EN 24063:1992, the following additionalrequirements shall be applicable.

In special cases supplementary ultrasonic examination can be required.

EXAMPLE: When short-circuit welding and/or where large thicknesses are involved.

In the first instance, the extent of this supplementary ultrasonic examination shall be 25 %.

Depending on the results of this examination, the pipeline operator can either:

- require supplementary examination or

- reduce the extent of this examination.

Dye-penetrant examination shall be carried out in accordance with EN 571-1:1997.

Magnetic-particle examination shall be carried out in accordance with EN 1290:1998.

The flow chart in Figure 1 identifies where the criteria for execution, extent and acceptancefor various non-destructive examination methods can be found in this and other documents.

Figure 1: Non-destructive examination procedures and acceptance criteria

EN 12732:2000

8.4 Time of inspection

All non-destructive examination shall be carried out before pressure testing, with theexception of final tie-in welds which are not subjected to the pressure test (”golden welds”).

8.5 Acceptance criteria

The pipeline operator shall specify the acceptance criteria.

The acceptance criteria given in Table G.1 for radiographic findings and in Table G.3 forultrasonic findings are based on workmanship criteria. The pipeline operator can use EPRGguidelines (see Annex G.2) or alternative acceptance criteria based on fracture mechanicsanalysis and fitness-for-purpose criteria, provided they are fully documented and based on aproven safe approach.

The results of the radiographic examination shall meet the acceptance requirements which aregiven in clauses 10 and 11.

Weld defects detected by means of ultrasonic examination shall be evaluated in accordance withthe requirements of Table G.3.

The acceptance requirements for alternative examination methods shall be determined from caseto case.

8.6 Recording of test results

A clear relationship shall exist between the examination report, the radiographs and the weldunder examination, and shall be indicated in a sketch or pipe logbook.

9 Documentation

9.1 General

The documentation is intended to prove that the welding requirements and test provisionsaccording to this standard are fulfilled.

This documentation shall be compiled in such a way that traceability is ensured.

9.2 Archiving requirements

Documentation shall be archived in accordance with the pipeline operator's policy.

10 Specific requirements for gas supply systems up to and including 16 bar MOP(distribution)

10.1 General

This clause contains specific requirements for the welding and inspection of gas supply systemsup to and including 16 bar MOP (distribution).

Table 1 defines the quality requirement categories.

EN 12732:2000

10.2 Welders

Welders shall be qualified in accordance with EN 287-1:1997, taking into account the essentialvariables as laid down in clause 6. For acceptance criteria in accordance with EN 287-1:1997reference can be made to Annex G.1.

For gas welding (procedure no. 311) of pipes of category A, welders' qualification requirementsare to be defined by the pipeline operator.

Welders employed in the installation of buried pipelines shall have passed their weldingexamination under site conditions. This requirement is deemed to have been fulfilled if theexamination is conducted in an area which simulates a pipe trench of the following dimensions:

- maximum length: 1,5 m

- maximum spacing between pipe wall and trench bottom: 0,4 m

- maximum spacing between pipe wall and trench wall: 0,5 m

Welders certificate shall clearly indicate, by reference to this standard, that the weldersqualification test has been performed under the conditions mentioned above.

10.3 Welding supervisory personnel

Welding specialists qualified to EN 719:1994 are qualified to act as welding supervisorsmonitoring welding work on site. For welding work in quality requirement categories A and B, thewelding supervisor can be a foreman welder with several years specialized technicalexperience.

10.4 Production welding

If feasible, working pits or bell holes should be constructed in the pipe trench. They shouldhave a minimum free length of 1,5 m at the weld area. The distance from pipe to bell hole bottomshould be not less than 0,4 m and from pipe to trench wall not less than 0,6 m.

Bell holes shall be kept free of water during welding work.

Segmental cuts up to 7,5� (tangents up to 15�) are permitted for pipelines and systems forquality requirement categories A and B. Segmental cuts up to 2,5� (tangents up to 5�) arepermitted for pipelines and systems in quality requirement category C.

In areas subject to ground movements and at unconcealed pipe spans and at pipelines on bridges,changes of direction using segmental cuts shall not be permitted.

10.4.1 Joint preparation

Socket joints according to prEN 1708-1 are allowed for all diameters in quality requirementcategories A and B, if approved by the pipeline operator.

Bell and spigot, socket or sleeve welds shall be set up so that the root gap of the fillet weld isthe minimum possible. No tools with sharp edges shall be used during this process. Where the endof the socket shall be forged, it shall be heated to a forging temperature suitable for thematerial quality.

The welding of alignment aids and similar temporary attachments onto pipelines should beavoided. If necessary, alignment aids and similar temporary attachments can be used with theapproval of the pipeline operator.

10.4.2 Welding

All welding, including repairs and welding of patches for repair, shall be carried out inaccordance with the approved welding procedure specification.

EN 12732:2000

10.5 Acceptance requirements

For radiographic examination reference can be made to Table G.1 or Table G.2.

For ultrasonic examination reference can be made to Table G.3.

10.6 Requirements for records and documentation

The following documents should be made available:

a) material certificate (only for category C);

b) welding procedure specification;

c) welding procedure approval record;

d) pipe logbook (only for category C);

e) welding procedure qualification record;

f) non-destructive examination reports;

g) radiographs;

h) pipe routing (as built).

11 Specific requirements for gas supply systems greater than 16 bar MOP (transmission)

11.1 General

This clause contains specific requirements for the welding and inspection of gas supply systemsgreater than 16 bar MOP (transmission). These welding aspects shall be taken into account inorder to reduce the risk of weld defects. Table 1 shows the area of application.

11.2 Welders

Welders can be qualified according to EN 287-1:1997 or in accordance with a standard of thepipeline operator. An example is given in Annex A.

If the pipeline operator has justifiable doubts regarding the skill of a welder in respect ofthe welding work to be performed, requalification with additional requirements can berequired.

11.3 Welding supervisory personnel

The monitoring of welding work on site can be delegated from the welding supervisory personnelin charge according to clause 4, Table 2, to a welding specialist qualified to EN 719:1994.

11.4 Qualification of welding procedures

The pipeline operator shall specify the requirements for the approval of the welding procedureaccording to the relevant part of EN 288. Table 2 gives an overview of the recommendedrequirements. The welding procedure shall be in accordance with EN 288-2:1992 and be submittedto the pipeline operator for approval prior to commencement of welding.

KV �

8 × 10 × KVP

SP

Page 21EN 12732:2000

For welding work on materials which have not been qualified by standard procedures according toEN 288-7:1995, as well as for special designs, qualification of the procedure shall be carriedout according to EN 288-3:1992 or, as specified by the pipeline operator, according to EN 288-8:1995.

EXAMPLE 1: cable connections for cathodic protection. EXAMPLE 2: work on ”live-lines”.

EXAMPLE 3: installation aids.

11.4.1 Testing requirements for welding procedure qualification

As transmission pipelines are subject to external forces, care shall be taken to ensure thatweld defects cannot become critical.

For grades L 485 and L 555 according to EN 10208-2:1996, matching of base and filler materialsis required and the use of Table 3 is recommended.

Testing should be carried out in accordance with EN 288-3:1992 or prEN 288-9, as appropriate.

However. depending on service and/or conditions to be experienced by the pipeline, morestringent requirements or additional tests can be specified by the pipeline operator.

EXAMPLE 1: overmatching of consumables.

EXAMPLE 2: impact testing.

EXAMPLE 3: transverse tensile testing.

EXAMPLE 4: all-weld-metal tensile testing.

11.4.2 Impact testing

In addition to prEN 288-9 and EN 288-3:1992, the following requirements are prescribed for theweld metal notched in the centre of the weld and in the heat-affected zone.

Minimum impact energy:

- Steel grades with specified minimum yield strength less or equal to 360 N/mm2

Average 27 Joule (J)Individual 20 Joule (J)

- Steel grades with specified minimum yield strength greater than 360 N/mm2

Average 40 Joule (J)Individual 30 Joule (J)

NOTE: If the EPRG rules are specified by the pipeline operator, the Charpy-V requirementsof 40 Joule average, 30 Joule individual shall be used (see Table G.2).

In addition to the above-mentioned standards, testing is required for all pipe wall thicknessesgreater than 5 mm. Where subsidiary tests are necessary because of limited wall thickness, themeasured impact energy (KV ) shall be stated together with the test piece cross-section (S )P P

measured under the notch in square millimetres.

For comparison with the requirements specified above, the measured energy shall be converted tothe impact energy KV (in Joules) using the formula:

EN 12732:2000

where:

KV is the impact energy for the full-size specimen, in Joules;KV is the measured impact energy, in Joules;P

S is the cross-section measured under the notch, in square millimetres.P

The specimen shall be as thick as possible.

The verification test temperature shall be equal to the minimum design temperature or, ifagreed, to the minimum exposure temperature which can occur.

11.4.3 Transverse tensile test

The tensile strength of the joint, including the fusion zone of each specimen, shall be equal toor greater than the specified minimum tensile strength of the pipe material. If the specimenbreaks in the weld metal, it shall be considered acceptable provided that the specified minimumtensile strength of the pipe material has been achieved.

11.4.4 All-weld-metal tensile test

If an all-weld-metal tensile test is specified (information in addition to that contained inthe 3.1.B certificate to EN 10204:1995), the test specimen and the tests should be in accordancewith the appropriate EN standard. The yield strength should be equal to or higher than thespecified minimum yield strength of the parent metal.

11.5 Production welding

11.5.1 General requirements

If feasible, working pits or bell holes should be constructed in the pipe trench. They shouldhave a minimum free length of 1,5 m at the weld area. The distance from pipe to bell hole bottomshould be not less than 0,4 m and from pipe to trench wall not less than 0,6 m.

Bell holes shall be kept free of water during welding work.

Pipes, pipeline parts and other components which require marking (in accordance withEN 10204:1995) shall be restamped or remarked next to the cutting line prior to cutting.

The minimum length of a single pipe to be welded into a pipeline shall be 0,5 times DN.

Where forged fittings are used in a tie-in situation, the fittings should have pipe-pups weldedto them before welding into the line so that the final tie-in is a pipe-to-pipe joint.

Segmental cuts shall be limited to 1,5� (tangents up to 3�). When segmental cuts are used onlymanual welding shall be allowed.

In areas subject to ground movements and at unconcealed pipe spans and at pipelines on bridges,changes of direction by segmental cuts are not permitted.

11.5.2 Joint preparation

Absence of laminations shall be proven by ultrasonic testing or other appropriate means, beforebranches, nozzles and structural parts are welded onto pipelines or other components and beforecutting is carried out (see Annex B).

Pipes and pipeline components shall be clamped in such a way that strain due to movement on theweld during welding is avoided.

The welding of alignment aids and similar temporary attachments onto pipelines shall not beacceptable.

EN 12732:2000

11.5.3 Welding

During welding, particular attention shall be paid to:

- preheat temperature;

- the time lapse between runs;

- the number of runs before work can be interrupted;

- the total time for weld completion;

- the welding energy for root pass for downhill welding with cellulosic electrodes.

In cases where tie-in welds are not subjected to hydrostatic testing and when welding steelgrades from Groups 2 and 3 according to EN 288-3:1992, cellulosic electrodes shall be permittedonly at the discretion of the pipeline operator.

11.5.4 Repairs of weld defects

When an external repair of the root is carried out, it shall be made to a qualified procedure.

If a test of a repair weld shows that the area is still defective, the seam shall be cut out andrewelded unless otherwise agreed by the pipeline operator.

11.6 Destructive testing of production welds

The minimum number of production welds to be tested shall be in accordance with Table 5. Weldsshall be tested in accordance with EN 288-3:1992 or, if required by the pipeline operator, inaccordance with prEN 288-9.

Table 5: Minimum number of production test welds as function of pipeline length

Pipeline length L Number of sampleskm

1 < L � 10 110 < L � 50 2

L > 50 2 plus 1 further sample per lengthof 50 km or part thereof

11.7 Acceptance requirements

For radiographic examination reference can be made to Table G.1 or Table G.2.

For ultrasonic examination reference can be made to Table G.2 or Table G.3.

When welding level grades from Groups 2 and 3 according to EN 288-3:1992 with wall thicknessesgreater than 10 mm which are not pressure-tested, then welds shall also be ultrasonicallyexamined (see Table 4, note 6). In case of welding with cellulosic electrodes, this examinationshall be carried out not sooner than 24 hours after the welding has been completed unless soakingis performed.

In case the pipeline operator uses EPRG guidelines (see Annex G.2) or alternative acceptancecriteria based on fracture mechanics analysis and fitness-for-purpose criteria it isrecommended to perform the non-destructive testing of the welds by combination of two differentinspection techniques.

EN 12732:2000

11.8 Requirements for records and documentation

Traceability of documents for each single weld joint shall be compiled which shall includeidentification of the welders employed and the welds produced by them.

The documents as listed below should be verified and checked prior to commissioning.

Records and documentation should include:

a) requirements of the relevant authorities;

b) approval on installation;

c) contractual conditions;

d) planning and execution documentation;

EXAMPLE 1: specifications, welding instructions, calculations and computations, designplans, part lists.

e) approval/certificate of suitability, also for subcontractors and suppliers ifapplicable;

f) qualification of welding personnel:

1) qualification of welding supervisory body according to EN 719:1994 and area ofresponsibility of welding supervisory body;

2) qualification of welders (welder's certificate);

3) qualification of operators of welding machines according to EN 1418;

g) qualification of test personnel:

1) qualification of test supervisory body according to the appropriate EN standard andarea of responsibility of test supervisory body;

2) qualification of testers according to the appropriate EN standard and duties oftesters;

h) proof of the suitability of the welding method according to EN 288 series;

i) certificates, authorizations, delivery confirmation for semi-finished products andcomponents;

j) written records on the execution of heat-treatment operations;

k) test records:

1) non-destructive examination and destructive tests;

2) soundness and strength tests;

l) report on special features of construction work as well as on special measures;

EXAMPLE 2: work under difficult conditions such as adverse, cramped conditions.

m) inventory and location of components;

n) pipe logbook;

o) if applicable, conformity declaration by the welding contractor, also by subcontractorsand suppliers;

p) approval records.

EN 12732:2000

12 Specific requirements for metering, regulating and compressor stations

12.1 General

This clause contains specific requirements for welding on and inspection of stations. Table 1defines the quality requirement categories.

12.2 Specific requirements

It is recommended that the same requirements are used for stations as for the general pipelineconstruction, according to the quality requirement category. The requirements relatingparticularly to construction below ground level are excluded. These include:

- examination of welders under site conditions (see 10.2 and 11.2);

- general requirements for working pits or bell holes (see 10.4, 11.5.1);

- destructive testing (see 11.6).

Additional measures can be required in certain circumstances.

EXAMPLE 1: When design temperature or vibration are considered critical.

EXAMPLE 2: When special materials are used for pipes and /or pipework.

EXAMPLE 3: When different grades of steel are being welded together.

EN 12732:2000

Annex A (informative)

Qualification for pipeline welders (Girth welds and branch connections)

A.1 General

In the case of fully mechanised processes, before execution of approval test, welders should beexamined about functional knowledge appropriate to the welding unit as specified in Annex B ofEN 1418:1997.

A.2 Execution of approval test

a) The test pipes to be welded should be of pipeline steel according to EN 10208.

b) Welding technique should be:

- single side no backing (ss nb) or

- single side with backing (ss mb) or

- both side (bs).

c) Welding shall be performed in an area which simulates a pipe trench of the following maximumdimensions:

- trench length: 1,5 m

- spacing between pipe wall and trench bottom: 0,4 m

- spacing between pipe wall and trench wall: 0,5 m

d) For pipes less than DN 400 the welder should complete the whole circumference of a joint.

e) For pipes equal or greater than DN 400 the welder should weld half the circumference of thejoint (12 to 6 o‘clock position) in which case he is qualified to weld over the entirecircumference.

A.3 Range of test pieces

Pipeline welders shall perform a test for the particular type of application. Parameters couldbe:

- Welding process;

- Welding position;

- Filler material (including combinations);

- Pipe material.

For an overall qualification for all diameters the welder shall perform as a minimum twodifferent diameters in at least two positions.

EXAMPLE: the combinations PC/PF or PC/PG according to EN ISO 6947:1997.

For (cellulosic or basic) downhill or flux cored arc welding the diameters shall be :

- DN 150 with a wall thickness in the range from 4,5 mm to 9 mm and

- 400 � DN � 800 with wall thickness > 10 mm.

EN 12732:2000

For other processes the dimensions should be:

- 50 � DN � 150 with wall thicknesses between 3,6 mm and 9 mm and

- 400 � DN � 800 with wall thickness > 10 mm.

Additionally, one DN 50 weldolet or equivalent in position PC on a pipe of at least DN 400 shouldbe welded.

A.4 Preparation

Filler material shall be approved, certified and commercially available. Welding shall becarried out according to an approved welding procedure specification. 10.2 should bemaintained.

A.5 Execution of test welding

The pipeline operator shall nominate an examiner. Unless otherwise agreed a notified body shallexamine the qualification. The welder shall identify himself with an appropriate document.Clear identification marks shall be present on the pipe before welding starts. Repairs duringwelding are not allowed.

A.6 Inspection

Both non-destructive examination and mechanical testing are required.

After finishing welding, the examiner shall execute visual examination. The quality should meetthe requirements of Annexes E and G.1.

All test pieces shall be X-rayed according to EN 287-1:1997 and examined according to table G.1quality requirement category D.

For automatic processes (metal active gas (MAG) welding/ metal inert gas (MIG) welding)ultrasonic examination shall be carried out instead of radiography, when the wall thicknessexceeds 8 mm. Weld quality should meet the requirements of Annex G.3 of this standard.

The weldolet shall be subjected to Magnetic Particle examination only.

A.6.1 Testing girth welds

Mechanical testing shall be performed on each part of the joint welded in the relevant weldingposition according to EN 287-1:1997. The four bend or fracture test pieces of 400 � DN � 800 testweld shall be taken from the 1, 3, 4 and 5 o‘clock positions. For the small diameter welderqualification test the weld test pieces shall be taken in accordance with EN 287-1:1997. Forcellulosic welds, a degassing heat treatment of 250 °C for up to 10 hours is recommended ontransverse bend test specimens.

A.6.2 Testing weldolets

Four macro specimens shall be taken from the fillet weld.

A.7 Approval range

A.7.1 Materials

When welding the combination as mentioned above the welder is qualified according to thisstandard for welding all pipelines in all diameters, wall thicknesses and material according toEN 10208 for the relevant procedures and positions.

The welder is only qualified to use the type of filler material for which he has been approved.

EXAMPLE: Cellulosic only qualifies cellulosic.

EN 12732:2000

A.7.2 Dimensions

When separate qualifications are performed the range is as follows:

- DN 50 qualifies all diameters up to and including DN 100 (category: small diameter);

- DN 150 qualifies all diameters between DN 100 and up to and including DN 250 (category:medium diameter);

- DN 400 qualifies equal to or greater than DN 250 (category: large diameter).

A.7.3 Technique

- Single side (ss) qualifies single side and both side (bs) and single side with backing (ssmb).

- Single side with backing (ss mb) only qualifies single side with backing.

- Both side (bs) qualifies both side and single side with backing (ss mb).

A.8 Duration of validity

The duration of validity for the certificate is six months.

Non-destructive testing (NDT) records shall be maintained according to small, medium and largepipe size categories, for the purpose of extending the validity of the welder certificates.

A.9 Certificate

The pipeline welder certificate shall be similar to that proposed in EN 287-1:1997

The certificate should clearly indicate by reference to this standard that the welderscertification test has been performed under the conditions stated in Annex A. The original certificate is non-transferable and shall be directly in the possession of thewelder or the contractor during execution of the work.

The examiner present during test welding shall sign and stamp the original certificate.

EN 12732:2000

Annex B (informative)

Testing of the base material (lamination test)

Ultrasonic test equipment should be used for lamination tests; wall thickness measuringinstruments should not be used for this purpose.

Transmitter/receiver twin test probes or a single-crystal probe with detection zone greaterthan near field zone should be used.

Ability to detect a flat-bottom hole of 2 mm diameter and a depth of 40 % of wall thicknessthrough to the respective rear wall should be ensured.

EN 12732:2000

Annex C (informative)

Wall thickness compensation/Design examples

Figure C.1: Weld joint in the case of inadmissible high edge offset; transition piece withcounterweld (dimensions in mm)

Figure C.2: Weld joint in the case of inadmissible high edge offset; machined off on root side

Figure C.3: Weld joint in the case of inadmissible high edge offset; machined off on root sideand counterwelded (dimensions in mm)

EN 12732:2000

Annex D (informative)

Critical aspects for hot-tap welding or welding on gas-pressurised pipelines

D.1 General

This annex refers to 7.3 and describes the general variables which should be maintained for hot-tap welding or welding on gas-pressurized pipelines of category D (transmission pipelines).Parts of them are essential and should be stated in the welding procedure specification. Thisannex applies to:

- Split tees and repair sleeves nominal diameter � DN 100

- Threadolets and weldolets nominal diameter � DN 100

- Set-on branches nominal diameter � DN 25

D.2 Definition

Temper bead method: A weld sequence whereby the heat-affected zone of the base material issoftened as much as possible.

D.3 Symbols

Hdm: Amount of diffusible hydrogen in 100 mg of weld metal.

D.4 Recommendations

D.4.1 Equipment

Mechanical control of welding current.

D.4.2 Supervision

Supervision should be performed by the pipeline operator or its nominee.

D.4.3 Safety precautions

Safety precautions should be taken and maintained in accordance with the pipeline operator'sstandard or the authority's regulations.

Grouping of materials should comply with EN 288-3:1992, Table 3.

D.4.4 Identification

Prior to commencement of work, identification marks should be checked for compliance with theoperator's standard.

D.4.5 Filler materials

Filler materials should be in accordance with clause 5.

The pipeline operator may specify a special brand. For the application, filler materialrequirements should be:

- specified minimum yield strength � 400 N/mm ;2

- ultimate tensile strength equal to or greater than 400 and up to and including 560 N/mm ;2

- A5 � 26 %;

- KV � 47 J/32 J;

EN 12732:2000

- the verification test temperature in accordance with the pipeline operator's standard;

- Hdm � 3 ml from 3 sets. Single value up to and including 3,5 ml is allowed;

- vacuum packaging should be specified;

- type of 3.1.B certificate in accordance with EN 10204:1995.

D.5 Weld preparation

Precautions should be taken to avoid arc strikes on the gas-pressurized pipeline in the case oflongitudinal weldments:

- by the use of backing strip;

- by adequate spacing between fitting and pipe.

Preparations should be in accordance with the appropriate EN standard.

D.6 Welding procedure

Description: The contractor should specify the applicable welding procedure. The weldingprocedure should be approved by the pipeline operator.

Approval: Approval should be given if the welding procedure meets the requirements of thepipeline operator's standard.

Qualification: The procedure qualification should be performed in accordance with the pipelineoperator's standard. (See also D.11).

Validity: The validity of the welding procedure qualification may be changed at the discretionof the pipeline operator.

D.7 Performance of the welder

Welders should prove their competence prior to commencement of work. A test weld should beexecuted and examined. (See also D.11).

The welding method and specimen should be approved by the pipeline operator.

The pipeline operator should qualify/approve the welders carrying out welding on gas-pressurized pipelines.

Validity: The validity of the welders performance qualification may be changed at thediscretion of the pipeline operator.

D.8 Precautions

To avoid cold cracking and burn-through, the following precautions are recommended:

- Normalized steels (used before 1970) can be more sensitive to cold cracking. The pipelineoperator may take special measures by preheating and/or reducing gas flow.

- A minimum wall thickness for safe working should be maintained. As a consequence, amaximum allowable rod diameter and minimum run-out length should be specified.

- Depressurizing of the pipeline should be considered for certain minimum wall thicknesses.

- A minimum flow should be maintained for certain minimum wall thicknesses, at theoperator's discretion.

EN 12732:2000

- A minimum distance between a fitting and other weldments should be specified by thepipeline operator.

D.9 Execution

Seam preparation: Weld ends on the inside and outside of the fitting or sleeve should be ground smooth.

Damaged surfaces: Minor surface damage can be repaired by grinding. Wall thickness reductionshould be limited to 95 % of the minimum allowable wall thickness unless otherwise specified. Asmooth transition to normal contour should be required with a maximum slope of 1:4.

Also applicable are 6.1, 6.1.5 and 6.1.8. With respect to 6.1.8, the pipeline operator should beinformed in the event of reportable defects.

There should be equal spacing between the fitting and the pipe.

The cap of the pipe seam weld should be removed by grinding, extending to 50 mm from each filletweld of the fitting.

Tack welding should be carried out by fully qualified welders.

Preheating for tack welds should be specified. If applicable, the minimum required length oftack welds should be 50 mm. The maximum distance between tack welds should be 300 mm. Tackwelding should be specified in the welding procedure specification.

The pipeline operator should specify preheating parameters, if applicable. The weldingsequence should be specified in the welding procedure specification.

Unless otherwise specified, the maximum electrode diameter for wall thicknesses up to 7,0 mmshould be 2,5 mm. Above 7,0 mm wall thickness, 3,25 mm electrodes can be used. Above 10,0 mm wallthickness, 4,0 mm electrodes may be used. Weaving is permitted up to twice the electrodediameter.

Buttering may be used as a means of avoiding cold cracking. The pipeline operator can specify thetemper bead method. To avoid excessive shrinkage, the specified weld sequence should be observed.

Each fitting shall be clearly marked.

D.10 Repairs

Each repair should require the pipeline operator's approval. Each repair should be specifiedand documented. Repaired welds should be 100 % inspected.

D.11 Procedure qualification record/welder performance qualification

The pipeline operator can specify special welding conditions for the welding procedure approval record . The procedure/performance test for welding on a gas-pressurized pipeline is optional.Testing should be in accordance with EN 288-3:1992. The pipeline operator may specify

EN 12732:2000

Figure E.1: Face angle between parent metal and weld metal

Annex E (informative)

Visual inspection of joints

E.1 General

This annex should be applied to all circumferential welds, branch and fillet welds. Visualinspection of joints should be performed in accordance with EN 970:1997.

Requirements are based on acceptance criteria as laid down in Annex G.

E.2 Recommandations

In addition to the requirements of 8.4 of EN 970:1997, it should be verified that the face anglebetween the parent metal and the weld metal is greater than 120� (see Figure E.1). In the case ofcircumferential welds, undercuts (with reference to Table G.1 or Table G.2,) should bepermitted provided these have a smooth transition to the parent metal.

EN 12732:2000

Annex F (informative)

Manual ultrasonic testing of weld joints for wall thicknesses between approximately 6 mm and10 mm

F.1 General

Testing details for wall thicknesses between approximately 6 mm and 10 mm are specified toensure a precise distinction between geometric and defect echoes on the screen, where testing iscarried out within the 50 mm test range measured within the shortened projection distance.Assessment of echo levels compared with circular disc reflectors as calibration values in thiswall thickness range is possible only to a limited degree because the test takes place in thenear field of the sound field.

For this purpose, the following equipment is to apply:

- Miniature angled test heads with 4 MHz nominal frequency, a beam angle of 70� and a fixedinstalled measuring staff.

- Calibration block with groove and edges in accordance with Figure F.1a. The thicknessshall not deviate from the nominal wall thickness of the pipeline to be measured by morethan 10 %.

- Calibration block with bored hole in accordance with Figure F.2a. The block shall be madefrom flat steel complying with EN 10025:1994, e.g. S 355 N, and shall have a minimumcross-section of 36 mm x 20 mm and a minimum length of 140 mm.

Calibration of the ultrasonic tester and setting of the test sensitivity shall be carried out inaccordance with F.2.

F.2 Calibration

F.2.1 Adjustment of spacing

The calibration of the ultrasonic tester shall be carried out in the shortened projectiondistance, actually in the 50 mm test range. The use of calibration block no. 2 according toEN 27963:1992 is to be preferred.

Using a calibration block as shown in Figure F.1a, a groove at spacing a (pos. 1) and a groove at1

spacing a (pos. 2) or an edge at spacing a (pos. 3) should each be scanned and the corresponding2 3

echo base points set to the shortened projection spacings shown in Figure F.1b belonging to thespacings a and a , or a , as applicable. By this the echoes should be set to at least 80 % of1 2 3

screen height.

F.2.2 Sensitivity adjustment when using the Distance Gain Size method

The shape and location of the sloping curve (reference line) for a circular disc reflector of1 mm diameter is shown in the Distance Gain Size diagram for the test head. The shape and location shall be specified by the test supervisory body, taking into account the respective acousticattenuation and transferred to the screen using a waterproof colour pen.

The test sensitivity will be determined on the basis of a cylindrical bored hole in thecalibration block as shown in Figure F.2a. The echo signal of the cylindrical bored hole will bemodulated to the level of the sloping curve using a dB amplification controller as shown inFigure F.2b.

The amplification must then be increased by 8 dB. This amplification takes account of thedifference in sensitivity between the signal from a circular disc reflector of 1 mm diameter andthe signal from a cylindrical bored hole of 2 mm diameter with the same acoustic path.

EN 12732:2000

NOTE: After the echo signal from the 2 mm cylindrical bored hole has been increased by 8 dB,the sloping curve for the wall thickness range from 10 mm to 12 mm will correspond to acircular disc reflector of 1 mm diameter (calibration standard). For the wall thicknessrange from approximately 6 mm to 10 mm, the sloping curve will correspond only approximatelyto a circular disc reflector of 1 mm diameter.

To summarize, the following dB additions apply for setting the required test sensitivity:2 mm cylindrical bored hole in the calibration block set to the levelof the sloping curve x dB

increase in amplification + 8 dB

transfer correction + dB

test sensitivity = dB

The additional amplification of 8 dB only applies when a miniature angled test head with anominal angle of 70� and a nominal frequency of 4 MHz is used.Miniature angled test heads with nominal beam angles other than 70� (e.g. 80�) or ominalfrequencies other than 4 MHz (e.g. 2 MHz) are also usable. But in these cases the sloping curve,the sensitivity adjustment and the increase in amplification has to be specified by the testsupervisory body.

Figure F.1a: Calibration block with rectangular grooves and edge (All dimensions are in mm)

Figure F.1b:Screen display for adjustment

EN 12732:2000

Figure F.2a: Calibration block with cylindrical boring (All dimensions arein mm)

Figure F.2b:Screen display for adjustment of test sensitivity

EN 12732:2000

Annex G (informative)

Acceptance criteria recommendations for on-site production welds

G.1 Acceptance criteria according to EN 25817:1992

Table G.1: Acceptance criteria according to EN 25817:1992

Quality requirementcategory in accordance Type/position of the weld joint

with Table 1

Assessment category toEN 25817:1992

A + B Assessment category DCircumferential welds except:

Serial nos. 2,3,4,5,6 = C

Branches, nozzles, fillet weldsSerial no. 8Long imperfections = CShort imperfections = D

Longitudinal seams h � 0,1 x T, but not more thanSerial no. 11

1,5 mm and a length of 50 mm

Unconcealed pipe spans; pipelineson bridges, pipeline sectionscrossing railways, major roads andmotorways, navigable waterways orlanding strips/runways

C Assessment category CCircumferential welds except:

Serial nos. 12,13,14,15 = D

Branches, nozzles, fillet welds Long imperfections = CSerial no. 8

Short imperfections = D

Longitudinal seams h � 0,1 x T, but not more thanSerial no. 11

1,5 mm and a length of 50 mm

Welds seams not included in thepressure test

Unconcealed pipe spans; pipelines Same requirements as givenon bridges, pipeline sections in quality requirementcrossing railways, major roads and category Dmotorways, navigable waterways orlanding strips/runways

Continued

EN 12732:2000

Table G.1 (continued): Acceptance criteria according to EN 25817:1992

Quality requirementcategory in accordance Type/position of the weld joint

with Table 1

Assessment category toEN 25817:1992

D Assessment category B except:

Circumferential welds Serial nos. 3,9,12 = C

Serial no. 8Long imperfections = CShort imperfections = D

Serial no. 21 (see note 1) = C

Serial nos. 24,25 not permitted

Branches, nozzles, fillet weldsSerial no. 11h � 0,1 x T, but not more than1,5 mm and a length of 50 mm

Longitudinal seams, sweepolets

For crater pipes(EN 26520:1991;ref.no. 2024)Same imperfections areacceptable as serialno. 5 = B

Serial no. 16Long imperfections = BShort imperfections = C

Serial no. 17

weld joints not included in thepressure test

If pipelines/units are laid/installed inbuilt-up areas

Imperfection with:l � 10 mmb � 4 mmh � 4 mmacceptable

Serial no. 18 (see note 2)

Unconcealed pipe spans; pipelines on Serial no. 26 (see note 3)bridges, pipeline sections crossingrailways, major roads and motorways,navigable waterways or landingstrips/runways

NOTE 1: Internal concavity of any length is acceptable, provided the density of radiographic image of theinternal concavity does not exceed the density of the thinnest adjacent base metal. If it does exceed this, thelength is limited to 10 mm in any 300 mm of continuous weld or the total weld length, whichever is less. Serialno. 21 includes burn-through.

NOTE 2: Permitted misalignment of surfaces:

Wall thickness (T) Permissible external Permissible internal misalignment misalignment

T � 10 mm 0,3 x T 1 mm on entire circumference10 mm < T � 24 mm 3,0 mm 2 mm over length DNT > 24 mm 0,125 x T 2,5 mm over length 1/3 DN

NOTE 3: Accumulated length of all imperfections in each 300 mm of continuous weld shall not exceed50 mm.

Concluded

EN 12732:2000

G.2 Summary of requirements for defect acceptance levels and defect limits

The EPRG guidelines on the assessment of defects in transmission pipeline girth welds are based onliterature reviews, an extensive laboratory test programme, published experimental data andaccepted fitness for purpose methodologies. The guidelines are structured in three tiers andspecify defect acceptance levels in Tier 1 (good workmanship) and defect limits in Tiers 2 and 3(fitness-for-purpose). The application of current welding standards can lead to quite differentdefect limits. but the EPRG guidelines provide uniform acceptance levels and defect limits, with acomprehensive technical justification [1].

[1] Gerhard Knauf and Phil Hopkins: The EPRG guidelines on the assessment of defects intransmission pipeline girth welds, 3R international, 35 (1996), Journal number 10/11,October/November, 1996, pp. 620-624

EPRGEUROPEAN PIPELINE RESEARCH GROUP

a co-operation of European gas transmission and pipe manufacturing companies

Address:Mannesmannröhren-Werke AGMannesmann ForschungsinstitutEhinger Straße 200, D-47259 DuisburgPostfach 25 11 60, D-47251 Duisburg

MEMBERSHIP OF THE EUROPEAN PIPELINE RESEARCH GROUP (EPRG)

BP International Limited, UKBG plc, UKBritish Steel plc, UKS.A. Distrigaz, BelgiumEuropipe GmbH, GermanyGaz de France, FranceILVA/Lamiere e Tubi S.r.I., ItalyMannesmannröhren-Werke AG, GermanyN.V. Nederlandse Gasunie, The NetherlandsPreussag Stahl AG, GermanyRautaruukki Oy, FinlandRuhrgas AG/PLE GmbH, GermanyShell Internationale Petroleum Maatschappij B.V., The NetherlandsS.N.A.M. S.p.A., Italy

EN 12732:2000

Tab

le G

.2.1

:Su

mm

ary

of

req

uir

emen

ts f

or

def

ect

acce

pta

nce

leve

ls (

Tie

r 1)

an

d d

efec

t lim

its

(Tie

r 2

and

3)

Tie

r 1

Tie

r 2

Tie

r 3

The

def

ect a

ccep

tanc

e le

vels

use

d in

Tie

r 1

can

be fr

om a

reco

gnis

ed, a

ppro

pria

te a

nd a

ccep

tabl

e tr

ansm

issi

on p

ipel

ine

girt

h w

eldi

ng c

ode.

Exi

stin

g co

mpa

ny s

tand

ards

, a C

EN

stan

dard

, nat

iona

l sta

ndar

ds ,A

PI 1

104,

or

BS

I 451

5 w

ould

be

appr

opria

te, p

rovi

ding

they

are

use

d w

ithin

thei

r kn

own

and

thei

r de

fined

lim

itatio

ns.

Fitn

ess

for

purp

ose

defe

ct li

mits

.

Wal

l thi

ckne

ss (

T)

is 7

mm

� T

� 2

5,4

mm

. Thi

s T

ier

can

beap

plie

d by

agr

eem

ent t

o w

all t

hick

ness

es o

utsi

de th

is r

ange

.W

all t

hick

ness

(T

) is

7 m

m �

T �

25,

4 m

m.

The

se d

efec

t lim

its a

re b

ased

on

the

assu

mpt

ion

that

eac

h de

fect

is c

onfin

ed to

a s

ingl

e w

eld

run

of h

eigh

t not

gre

ater

than

3 m

m. I

f the

re is

a s

uspi

cion

of a

def

ect b

eing

of d

epth

gre

ater

than

this

wel

d ru

n, it

sha

ll be

rep

aire

d.

The

Cha

rpy

V e

nerg

y of

the

wel

d at

the

min

imum

des

ign

tem

pera

ture

for

the

pipe

line

shal

l be:

ave

rage

= 4

0 J,

min

imum

= 3

0 J

usin

g a

full

size

spe

cim

en. (

The

num

ber

of to

ughn

ess

spec

imen

s, th

eir

orie

ntat

ion

and

loca

tion,

will

be

spec

ified

by

the

resp

onsi

ble

engi

neer

and

take

due

acc

ount

of t

he w

eldi

ng p

aram

eter

s, p

ipel

ine,

its

oper

atio

n an

d th

e w

eld

defe

cts

expe

cted

.) S

ub-s

ize

spec

imen

s sh

ould

hav

e to

ughn

ess

requ

irem

ents

red

uced

pro

rata

with

thei

r di

men

sion

s.

The

wel

d to

ughn

ess

shal

l hav

e an

ave

rage

Cha

rpy

V v

alue

of 4

0 J

and

am

inim

um v

alue

of 3

0 J

at th

e m

inim

um d

esig

n te

mpe

ratu

re fo

r th

e pi

pelin

ean

d a

mea

n cr

ack

tip o

peni

ng d

ispl

acem

ent (

CT

OD

) to

ughn

ess

of 0

,15

mm

and

a m

inim

um C

TO

D to

ughn

ess

of 0

,10

mm

at t

he m

inim

um d

esig

nte

mpe

ratu

re. (

The

num

ber

of to

ughn

ess

spec

imen

s, th

eir

orie

ntat

ion

and

loca

tion,

will

be

spec

ified

by

the

resp

onsi

ble

engi

neer

, and

take

due

acco

unt o

f the

wel

ding

par

amet

ers,

pip

elin

e, it

s op

erat

ion

and

the

wel

dde

fect

s ex

pect

ed.)

Tra

nsve

rse

AP

I ten

sile

test

s sh

ould

be

carr

ied

out,

with

the

wel

d re

info

rcem

ent r

emov

ed. T

he te

sts

are

acce

ptab

le if

the

spec

imen

s fa

il in

the

pipe

mat

eria

l or

if th

e sp

ecim

ens

brea

k in

the

wel

d m

etal

whi

ch h

as a

tens

ile s

tren

gth

grea

ter

than

or

equa

l to

the

min

imum

spe

cifie

d te

nsile

str

engt

h of

the

pipe

mat

eria

l.

By

agre

emen

t, fu

rthe

r te

sts

can

be c

arrie

d ou

t to

ensu

re th

atth

e yi

eld

stre

ngth

of t

he w

eld

is e

qual

to, o

r gr

eate

r th

an, t

heyi

eld

stre

ngth

of t

he p

ipe

mat

eria

l.

The

def

ect l

imits

are

bas

ed o

n th

e as

sum

ptio

n, a

nd r

equi

rem

ent,

that

the

wel

d m

etal

yie

ld s

tren

gth

shal

l be

equa

l to,

or

grea

ter

than

, tha

t of t

he p

ipe

mat

eria

l. T

he m

easu

rem

ent o

f thi

s yi

eld

stre

ngth

, and

the

loca

tion,

type

and

num

ber

ofsp

ecim

ens,

sha

ll be

by

agre

emen

t.

The

rat

io o

f yie

ld to

ulti

mat

e te

nsile

str

engt

hof

the

pipe

mat

eria

l sha

ll no

t exc

eed

0,90

.T

he r

atio

of y

ield

to u

ltim

ate

tens

ile s

tren

gth

of th

e pi

pe m

ater

ial

shal

l not

exc

eed

0,85

.

Thi

s T

ier

can

be a

pplie

d to

girt

h w

elds

pro

vidi

ngth

at th

e ap

plie

d ax

ial s

trai

n in

the

pipe

is n

otgr

eate

r th

an 0

,5 %

.

Thi

s T

ier

can

be a

pplie

d to

girt

h w

elds

pro

vidi

ng th

at th

e ap

plie

d ax

ial

stre

ss is

not

gre

ater

than

the

pipe

yie

ld s

tren

gth.

The

def

ect l

imits

app

ly to

pip

elin

e gi

rth

wel

ds th

at a

re b

etw

een

pipe

s of

equ

al g

rade

, thi

ckne

ss a

nd a

re s

ubje

cted

to 1

00 %

non-

dest

ruct

ive

test

ing.

The

min

imum

spe

cifie

d yi

eld

stre

ngth

of t

he p

ipe

mat

eria

l sha

ll be

� 4

83 N

/mm

.2

Non

-pla

nar

defe

cts

wic

h ar

e su

rfac

e br

eaki

ng s

houl

d be

trea

ted

as p

lana

r de

fect

s.

Pip

elin

es s

ubje

cted

to o

nero

us fa

tigue

dut

y or

sev

ere

envi

ronm

enta

l loa

ding

s or

effe

cts

may

req

uire

hig

her

leve

ls o

f acc

epta

nce

whi

ch a

re n

ot in

clud

ed in

this

Ann

ex G

.2.

EN 12732:2000

Table G.2.2: Summary of defect acceptance levels (Tier 1) and defect limits (Tier 2 and Tier 3)

Type of defectTier 1 Tier 2 Tier 3

Acceptance criteria Limit criteria Limit criteria

External profile Excess weld metal should be uniform and not more than 3 mm in height. Itshould merge smoothly with the parent metal and not extend beyond theoriginal joint preparation by more than 3 mm each side. No area should havethe weld face lower than the adjacent pipe surface.

Internal profile The root bead or any concavity should merge smoothly into the adjacentsurface but at no point should the weld be thinner than the pipe thickness.

Root concavity - Length 25 % of weld circumference

- Depth 1,5 mm or 0,1 x T (if less)

Undercut (cap) - Length 50 mm 7 x T

Figure G.1- Total 50 mm in 300 mm or 15 % of 7 x T in any 300 mmcircumference (if less)

- Depth 1 mm or 0,1 x T (if less) Assumed to be < 3 mm

Undercut (root) - Length 25 mm 7 x TFigure G.1

- Total 25 mm in 300 mm or 8 % of 7 x T in any 300 mmcircumference (if less)

- Depth 1 mm or 0,1 x T (if less) Assumed to be < 3 mm

Inadequate - Length 25 mm 7 x Troot penetration Figure G.1


Incomplete - Length 25 mm 7 x T(lack of) root fusion Figure G.1


Incomplete - Length 25 mm 7 x T(lack of) cap fusion Figure G.1


Incomplete - Length 50 mm 7 x Tfusiondue to cold lap Figure G.1


Lack of - Length 50 mm 7 x Tsidewall fusion

Figure G.1- Total 50 mm in 300 mm or 15 % of 7 x T in any 300 mm

circumference (if less)

Lack of - Length 50 mm 7 x Tinter-runfusion Figure G.1

- Total 50 mm in 300 mm or 15 % 7 x T in any 300 mmof circumference (if less)

Continued

EN 12732:2000

Table G.2.2 (continued): Summary of defect acceptance levels (Tier 1) and defect limits (Tier 2 and Tier 3)



Cracks Not allowed

Crater cracks 4 mm

Burn-through 6 mm- Individual

- Total 2 per 300 mm

Porosity, - Individual 3 mm or 0,25 x T (if less)T < 10 mm

Figure G.1

- Total When projected radially through the weld, notto exceed a total area of 2 % of the projectedweld area in the radiograph, calculated bymultiplying the length of the weld affected byporosity, with a minimum of 150 mm, by themaximum width of the weld.

Porosity, - Individual 6 mm or 0,25 x T (ifT � 10 mm less)

as for T < 10 mm- Total 5 % of projectedarea on

radiograph

Hollow bead, -Individual 50 mmT < 10 mm

Figure G.1

- Total 50 mm in 300 mm or 15 % of circumference (ifless)

Hollow bead, - Length 6 mm or 0,25 x T (ifT > 10 mm less)

as for T < 10 mm- Total 5 % of projectedarea on

radiograph

Slag, - Length 50 mmT < 10 mm

Figure G.1(if less)- Total 50 mm in 300 mm or 15 % of circumference

Slag, - Length 40 % ofT � 10 mm circumference

- Total as for T < 10 mm

- Width 3 mm

Inclusions, - Total 12 mm in 300 mm and 4 in 300 mm Figure G.1T < 10 mm

- Width 3 mm or 0,5 x T (if less)

Inclusions, - Total 40 % of Figure G.1T � 10 mm circumferenceas for T < 10 mm

- Width 3 mm

Defect accumulation, 100 mm in 300 mm or 15 % of pipe circumference Figure G.1T < 10 mm (if less), excluding porosity

(Root concavity is not included in accumulation calculations, unless itcauses

the weld thickness to be less than that of the pipe.)

continued

EN 12732:2000

Table G.2.2 (concluded): Summary of defect acceptance levels (Tier 1)and defect limits (Tier 2 and Tier 3)



Defect interaction, Inherent in defect accumulation criteria If a planar, slag orT < 10 mm porosity defect is

separated from a planardefect by a distancesmaller than the lengthof the shorter of thetwo defects, thenrecategorize as asingle planar defect oflength equal to the twoindividual lengths +separation. Figure G.1gives limits forinteracting planardefects.

Defect accumulation, 100 mm in 300 mm or The larger of 7 x T inT > 10 mm 15 % of pipe any 300 mm or 100 mm in

circumference (if any 300 mm, excludingless), excluding porosity. Slag is notporosity. included in the

accumulationcalculation, providedpipe material strength� 450 N/mm . Figure G.12

Accumulation of planardefects shall be � 15 %of circumference.Accumulation of planarand non-planar defectsshall be � 40 % ofcircumference.

(Root concavity is not included in accumulation calculations, unless itcauses

the weld thickness to be less than that of the pipe.)

Defect interaction, Inherent in defect If a planar, slag or porosity defect is separatedT � 10 mm accumulation criteria. from a planar defect by a distance smaller than

the length of the shorter of the two defects,then recategorize as a single planar defect oflength equal to the two individual lengths +separation.

The recategorized Figure G.1 gives limitsplanar defect should for interacting planarhave the same identity defects.as the planar defect.

Concluded

EN 12732:2000

FigureG.1:Girth weld defects limits for Tier 3 (Wall thickness in mm)

G.3 Method and acceptance criteria for ultrasonic inspection assessment

G.3.1 Distance Gain Size method

The Distance Gain Size method should be used for the assessment of ultrasonic indications. The recordinglimits given in Table G.3.1 are applicable. Indications of defect reflections which exceed the results inTable G.3.2 are inadmissible.

G.3.2 Comparative Element method

When using the Comparative Element method, the test sensitivity after inclusion of the comparative line ona 3 mm cross hole shall be increased by 6 dB. Assessment shall be in accordance with Table G.3.2.

G.3.3 General

Adjacent fault reflections at the same depth shall be separated by at least the length of the largestindividual fault reflection; if not, they should be considered as a continous fault reflection length.

The examination shall be performed in accordance with test rate 2 as given in EN 1714:1997. In criticalcases or to improve the assessment, the test rate should be increased or other additional test procedures(e.g. radiographic examination) should be used.

Weld joints on materials which have a tendency to hydrogen-induced cracking shall be checked after thepost-welding diffusion of hydrogen, at the earliest 24 hours after the welding.

EN 12732:2000

Table G.3.1: Recording of indications

Calibration standards and fault reflection lengths using the Distance Gain Size method

Wall thickness (T)mm

Calibration level - Sensitivity setting Fault reflectioncircular disc amplitude below lengths

reflector calibration level to be recordeddiameter by dB above this length

mm mm

6 < T � 10 1,0 6 10

10 < T � 15 1,0 6 10

15 < T � 20 1,5 6 10

20 < T � 40 2,0 6 10

T > 40 3,0 12 10

Table G.3.2: Assessment of indications using the Distance Gain Size method

Maximum allowable numbers and sizes of reflectors

Wall thickness T * lengths of reflectors calibration level in mm per echo** dB

Number of indications per m of seam

Maximum allowable Echo level above

mm

� 6 � T � 10 5 10 � 6and 2 20 � 6

10 < T � 20 10 10 � 6and 3 20 � 6and 1 10 � 12***

20 < T � 40 10 10 � 6and 4 25 � 6and 1 10 � 12***

40 < T � 60 10 10 � 6and 4 30 � 6and 1 10 � 12***

NOTES:

* If wall thicknesses differ, the lower wall thickness shall be decisive.

** For confirmed volume defects (not in the vicinity of the surface), fault lengthsexceeding the calibration levels by up to 6 dB can be allowed up to 1,5 times the allowablelength. Confirmation may take the form of a radiographic examination.

*** The acceptability of single, large defects shall be confirmed on the basis of randomsamples, e.g. by means of radiographic examination.

1 2 4

3 5

6

Weld/braze metal Parent metalsurface

Weld heat-affected zone (visible after etching)

NOTE:Hardness impressions 2, 3, 4 and 5 should be entirely within theheat-affected zone and located as close as possible to the fusionboundary.

All dimensions are in millimetres

Page 47EN 12732:2000

Annex H (informative)

Recommendations for brazing and aluminothermic welding of anodic bonding leads

H.1 Joining techniques

Full details of the joining technique and associated equipment should be submitted to the pipelineoperator for approval prior to use and should conform to the manufacturer‘s recommendations.

H.2 Procedure qualification

Prior to starting, the contractor should submit a preliminary welding procedure specification to thepipeline operator for approval. The procedure should be qualified by making three consecutive test jointsin the presence of the pipeline operator on material to be used in production. The test material should beselected by the pipeline operator to represent the upper quartile of the carbon equivalent range.

The electrical resistance of each joint should be measured and should not exceed 0,1 �. The mechanicalstrength of the joint should be tested by means of a sharp blow from a 1 kg hammer.

All three test joints should be sectioned and prepared for metallographic examination. The following testsshould be performed on the sections.

a) Copper penetration measurement The depth of copper penetration below the surface of the pipe material should be measuredmetallographically. The fusion line of the weld or braze should not be more than 1mm below the pipesurface. Intergranular copper penetration of the pipe material should not exceed 0,5 mm beyond thefusion line when a micro-section is examined at a magnification not exceeding x 50.

b) Hardness survey Each section should be tested using a 10 kg load. A traverse should be made across the weld zone as shownin Figure H.1 and should consist of at least six impressions; two in the heat-affected zone each side ofthe weld/braze and one in the parent metal each side of the weld/braze. The hardness values should notexceed 325 HV10, or they should be as specified by the pipeline operator.

Figure H.1:Recommended locations for hardness traverses and impressions for brazing and aluminothermicwelding

H.3 Operation qualification

Prior to carrying out production work, each operator should complete three test joints which should passthe tests for electrical conductivity and mechanical strength (hammer test) required in H.2. All weldingand tests should be witnessed by the pipeline operator.

EN 12732:2000

H.4 Production joints

The attachments should be located at least 150 mm from any seam or circumferential weld. The weld areashould be clean, dry and free from oil, grease, mill scale or other foreign matter. Preheating should beapplied as specified in the approved procedure.

All attachments should be tested for mechanical resistance strength (hammer test), followed by anelectrical continuity test, both as recommended in H.2.

Should any attachment prove to be defective, it should be carefully removed, ensuring that the parentmaterial thickness is not reduced below the specified tolerances. Rejoining should be carried out at a newlocation on the pipe.

EN 12732:2000

ANNEX I (informative)

Bibliography

EN 288-1:1992 Specification and approval of welding procedures for metallic materials - Part 1: General rules for fusion welding

EN 444:1994 Non-destructive testing - General principles for the radiographic examination ofmetallic materials using X-rays and gamma-rays

EN 462-1:1994 Non-destructive testing - Image quality of radiographs - Part 1: Image qualityindicators (wire type) - Determination of image quality values

EN 462-2:1994 Non-destructive testing - Image quality of radiographs - Part 2: Image qualityindicators (step/hole type) - Determination of image quality value

EN 1712:1995 Non-destructive examination of welds - Acceptance criteria for ultrasonicexamination of welded joints

EN 10025:1994 Hot rolled products of non-alloy structural steels; technical delivery conditions(includes amendment A1: 1993)

EN ISO 6947:1997 Welds - Working positions, definitions of angles of slope and rotation

La pubblicazione della presente norma avviene con la partecipazione volontaria dei Soci,dell’Industria e dei Ministeri.Riproduzione vietata - Legge 22 aprile 1941 Nº 633 e successivi aggiornamenti.

UNIEnte Nazionale Italianodi Unificazione

Via Battistotti Sassi, 11B20133 Milano, Italia

UNI-EN 12732 (2005)

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Transcript of UNI-EN 12732 (2005)