Weld Quality

WeldingQualification

&Certification

._._---~-----------~-------

------- --------- -- -------- ------- - ------_.~-------

.ecture 14 p1

Lecture ~3cope

• Need for welding qualification

• Codes & standards requirements- Welding procedure specifications- Welding procedure qualification- Welding operator qualification

• Company certification

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----_.. - .._--- -_. -------_.

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- -_..-_.------ -_. ----_.

p2

Need IFor Weld Qualification

• Many variables influence weld quality, related tothe parts to be joined, the welding process andwelding operator skill

• The purpose of qualification is to demonstratethat welding procedures and personnel areadequately controlled and are capable ofacceptable results

• Such tests cannot foretell performance inproduc::tion. Quality of the production weldsshould be determined by inspection during andafter the actual welding.

L

Lecture 14

Codes & Standards

• Application codes & standards that specifyqualification requirements for weldinginclude:- ASME Boiler and Pressure Vessel Code

=~~~ ~~11 ~:~:~~i:e~~~~Code ill~.~lft- API 1104 Standard for Welding Pipelines and Related

Facilities- eSA W59 Standard for Welded Steel Construction

• Standards for weld qualification- AWS B2.1 Wt~lding Procedure and Performance

Qualification

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14 p4

lecture 14

Codes & Standards Requirements

• A common approach to qualify weldingprocedures is by preparation and testing ofstandard test pieces. The qualification testsneed not be repeated unless the weldingprocedure specification is changed.

• Some' pressure vessel standards require testplates to be welded at the same time as thevessel seams and subsequently tested.

• Other standards accept certain weldingprocedures as "prequalified"

pSi

e14

Welding I)rocedure Specification

• Standards normally require the contractor toprepare and qualify Welding ProcedureSpecifications (WPS)

• A WPS should define the welding variables insufficient detail to ensure that the requiredquality is met

• Standards differ with respect to the generalityor specificity of WPS- Some standards are very specific in defining the content

of a WPS e.g. ASME Section IX. Other standards aremore general

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p6

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r------~----

Welding Procedure Specifications-Typical VVPS Contents

• scope• Base metal

• to simplify qualifications,standards often group basemetals by similar composition orstreng1h levels

• Welding process• Filler metal• Type of current and range• Arc voltage• Travel speed• Heat input

• Joint preparation _• Welding details• Welding positions• Preheat & interpass

temperatures• Post weld heat treatment

and finishing

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lecture 14 p7

,14

ASME Salmple WPS

p8

( )

QW-482 1992 SECI10N IX

QW~Z SUGGI5STED FORMAT FOR WELDING PROCEDURE SPECIFICATIONS (wPSI(See ClW.zOO.1, Section IX. ASME Boller end P........V~ Code'

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........... ..,... MltIlllMd for fIIOIdl.......- ....._ .... 1

'BASE METAUI_' ,..... I _ .... --.!'--_,

Oft SAIe 'flwdoli type"" --.;;:,;,~ :.r....:::;l~-;:l'----'

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174'

NONMANQA~AI'Pl!NDIX A QW-482

QW-4812 ee.tclo cOn..~

POSTWELD HEATTREATME~ ~071

T............ _ "'or-Il"""EEo:=...-------ro.. _ N ..t:AL- _POSITIONSI_I 5 ,._Co... a-_--='iJ"'1.J. ~

werding PwOQiellion: Up,---,Xc-_PoII.ionCllof Fillet . I- -l

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Percent Compolit'on

G_al {Mixture' Ftow RIlle

Shtefding

Tr.Uing

Backing

ELECTRICAL CHARACTERISTICSfO~tem.nt ACo< DC $"- Rc=.U)~"ily _~ fRMtel .... Val. (R....t _

IAmpf Hd voIli range Ihoufd be hlCOrdMl for MCh "ect:rode ,il.,PQIitioft. lind thick....... nc. ,",it tnf,Jtmltion INY be ..... in -. gb­.... form 1kniI. to ttult shown belo-.I

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le.g., .Remarks. Com­

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Addition. Techntque.

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ll-l~ _.

175

WPS Clualification

• The pu rpose of qualification is to show thatweldin!~ in accordance with the WPS will­produce sound welds with adequateproper1~ies.

• The WPS qualification requirements arespecifil:!d by the applicable standard.

• Qualification may be achieved by:1. Use of prequalified welding procedures2. Qualification tests3. Mock-up tests

L _

Lecture 14 p9

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WPS Qualification

• Prequalified welding procedures- The concept of prequalification is based on the reliability

of certain provl~n procedures as defined by the code orstandard (e.g. GSA W59, AWS 01.1)

- The contractor is nevertheless required to prepare WPSdocuments and to accept responsibility for their use.

- Any deviation from the standard negates the prequalifiedstatus

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e 14 P 10

lecture 14

WPS Clualification

• Prequalified weldinq procedures~

• Qualification tests- Qualifk~ation tests are intended to demonstrate that theweldin!~ procedure results in sound welds with acceptablemechanical properties

- Tests need not simulate the actual conditions for a givenjob. They usually consist of conventional butt joints onplates or pipes

- Base 2lnd filler materials, welding variables and heattreatml~nts must follow production plans within specifiedranges.

- However, other variables such as joint geometry orweldin!~ position might not be considered as qualificationvariabl·es

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P 11

-------- -------------------,1-----WPS QUcllification

• Prequalified welding procedures

• Qualification tests

• Mock-up te:sts- Mock-up tests are intended to simulate actual production

or field conditions.- Codes and standards do not require preparation of

welded mock-ups- However, mc,ck-ups can help to anticipate or avoid

problems in production. They are also useful when difficultaccess or other practical considerations may influenceresults in-situ, such as repair welding of nuclear plants.

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I Tests elf Qualification Welds

• Specimens are removed from the samplewelds for examination and testing

• The type and number of tests depend on therequire!ments of the particular standard

• Commonly specified tests include:- tensile tests- guided bend tests- Charpy notch toughness tests, or other fracture

toughness tests such as drop weight tests- macro-etch tests- non-de,structive examination

L -------l

Lec:ture 14 p13

Mechanic:al Test Specimens (

TRANSVERSESPECIMEN

LONGITUDINAL WELDSPECIMEN

MINATURE ROUNDSPECIMENS DEPENDING ON T

IDENTICALDIMENSIONS

CHARPY.~~

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!14 P 14

1--- -----~--.---...-------------------,

Face 8~ Root Bend Tests

WELD JOINT

FACE BEND

~~~~ROOT BEND~ SIDE BEND

Lecture 14 P 15

Guided Bend Test Jigs....,....-.:rt:r

sHClULDEflS OR -t.:t>tA

ROU.£2lS

n·IR.~·+ Itt Imlt\.. .. .. ,

2A+lfT-I/" lnJI1Jij~

r • $PEQMEN THICKNESS

T • SPECIMEN THIQ(NESS

(I) WnII11-ArouM '-I TeIt Jig

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e 14 P 16

ICharp:v Impact Specimen

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12 mm) mm

~: 0.010 in.IO.2M mm)

e

Lecture 14

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p17

,------Recordin!~ Test Results

• The we1dinn conditions and the test results areentered on a Procedure Qualification Record(PQR)

• If the test re~sults meet the requirements of thestandard, the PQR is certified by the contractorand the third-party inspector

• The WPS may then be issued for production

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314 P 18

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,----­I

ASME Sample PQR

Lecture 14 P 19

QW-483 1992 SEC110N IX

QW-483 SUGGESTED F(IRMAT FOR PROCEQU"E Ql.IAUFlc;ATlON RECORD WQR)(SH QW-200.2. flection IX. ASME BciIIer end P_,. V..... COde)

R-..d Ac:tue1 Conditions UMd to Weld Teat Coupon.

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JOINTS tQW-4021

(Pet'cenl Composition

G.slft) fMixturel Flow Rate

ed IOf e*=h ftUer metal Of ptoe:eu uwdJ

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l:BtfAoi'J !: Ll ('1t,..)

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FILLER METALS IOW.c04t

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CFor comb,,,allOf'l qu.I..~bons. the depo"led weld melal ttl

BASE METALS IOW..031 .sA I () bu. Spec.

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176

Ii

NONMANDATORY APPENDIX A

QW-483 (Back)

QW-483

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Splc'menNo. ­T-

T...T--. '- erat Ex-.

, Mils

IIr:.S'btJc; I LLL rlJiW~1f.i{.Manufacturer ...:.. _

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6t.., . I f). ~I .Dote By _

COeIaiI of reccHd of ........ illustrMive only and fNy be modified to conform to the iype and number of tescs required by the Code.'

177

~14

Changes in a qualified WPS

• If a WPS is to be revised or modified beyondthe qualified ranges of the "essential variables"it is necessary to do additional qualificationtests

• If the changE~s are within the qualified ranges ofessential variables, then a revised WPS can beissued without requalification

• A PQR may support several WPS

• Since the PQR is a certified record of aqualification test, it should not be revised.

p20

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(

Welder Performance Qualification

• WeJder or welding operator qualification testsare per1formed to determine the ability of thepersons tested to produce acceptable welds

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Lecture 14 p21

Performance Qualification Req'ts

• Most standards require each welder or weldingoperator to make one or more test welds inplate or pipe

• Variables that affect the ability of welders tomake sound welds are considered qualificationvariables. These include:- welding proc:ess- filler metal- welding position- joint detail- plate thicknElss- welding tech nique

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e14

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P22

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Standard Welding Positions - Plates

Te,st Position 1G Test Position 2G

Te!;t Position 3G

~---

----------------

Test Position 4G

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-----------------------

Lecture 14 p23

,--------------

Welding Positions-Pipes (

~~.-t;2J.J-.l16.

Tellt Position 1G

Test Position 2G

Test Position 6G

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Perforrnance Qualification Tests

• Test spl3cimens may be groove welds or filletwelds- groove weld qualification usually qualifies the operator to

weld bClth groove and fillet welds- fillet weld qualification limits the welder to fillet welds in

only thEI position qualified or less difficult positions

• Tests consist of either bend tests, macro-etchtests or radiography

• The weIder who prepares a test plate for aprocedure qualification is usually qualifiedwithin the variables in the WPS.

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lecture 14

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p25

Performan~::e Qualification Records

• Responsibility for performance qualificationrecords lies with the employer

• After succe8sful qualification of a welder theemployer and third party inspector certify theperformancE~ qualification record.

• Most codes limit the duration of qualification tothree to six months inactivity

• For most codes qualification may be extendedindefinitely provided the welder performssatisfactory work within the stated period

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114 p26

Lecture 14

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CompClny Certification

• Some standards extend qualification to thecompany's organisational practices- ASME Boiler and Pressure Vessel Code

• requirE~ audit by ASME of a company's quality control programbefore issuing a code symbol stamp for construction ofcompcnents

• Sectiol1 III for nuclear components requires a quality assuranceprogram

-CSA WS9/W47.1• requims employment of designated welding engineers and

welding supervisors, and preparation of welding standards andWPS uudited by Canadian Welding Bureau

-ISO 9000• generalized quality assurance program

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