cswip 3.1_welding inspection-wis5-2006.pdf

7/27/2019 CSWIP 3.1_Welding Inspection-WIS5-2006.PDF

1/357

TWI woRLDCENTREORW #.1?$IH#INING

WELDINGNSPECTION(wts5)

- t-t --1.-tvUKAS

xsoilNHct$tngroN025

TWILtd,Trainingand Examination ervices


2/357

WELDINGNSPECTIONCONTENTS

V

V

TYPICALDUTIES FWELDINGNSPECTORSTERMSANDDEFINITIONSWELDINGMPERFEGTIONSDESTRUCTIVEESTINGWPS WELDERQUALIFICATIONSMATERIALSNSPECTIONCODESANDSTANDARDSWELDING YMBOLSINTRO OWELDING ROCESSESMMAWELDINGTIGWELDINGMIG/MAGWELDINGSUBMERGEDRCWELDINGWELDING ONSUMABLESNONDESTRUCTIVEESTINGWELDREPAIRSRESIDUAL TRESS NDDISTORTIONHEATTREATMENTCUTTING ROCESSESARCWELDING AFETYWELDABILITY FSTEELSPRACTICALISUAL NSPECTIONAPPLICATIONNDCONTROL FPRE-HEATCALIBRATIONMACRO/MICROXAMINATIONAPPENDIX

V Vf v

1 5 .017.4

I I d l t I

19 .020.022.O23.024.O25.026.0

v

Welding nspectionRev0 Jun06Copyright@2006,TWILtdWORLD CENTREFORMATERIALS ]OININGTECHNOLOGY

TWIwflt


3/357

, , ( r a " iP . i f ,Y ) ' , " .

Section01TypicalDutiesof Welding nspectors

WeldingnsPectionRe v0 Ju n06Copyright 2006,TWILtd'f\IrI woRLDcENTREFoR--;- MATERTALSJOTNINGWU, rEct{NolocY


4/357

1.0 VISUAL INSPECTIONAND TYPICAL DUTIES OFWELDINGNSPECTORS1.1 GENERAL

welding Inspectorsare employed o assist.with the quality control (oc)activities hat are necessary o "niur" that welded items will meet specifiedrequirementsnd be it for heirapplication'Fo remp loye rs tohavecon f idence in the i rwo rk ,we ld ing lnspec to rsneed tohave he ability o understand/interprethe variousQC procedures nd also havesound nowledge fweldingechnology'Visual nspections oneof theNon-Destructivexaminationisciplines nd orsomeapplications aybe heonly ormof NDE'

Formoredemandingervice onditions,isualnspections usually.followedy

one or moreof the otherNOt tecnniques surfacecrackdetection nd volumetricinspectionf buttwelds'Application tandards/Codessually pecify or refer o otherstandards)heacceptanceriteriaor weld nspection nd may be veryspecific bout he particulartechniqueso be used or surface rackdetection nd volumetricnspection'heydonotusually iveanyguidancebout asic equirementsorvisualnspection'

Guidancendbasic equirementsorvisualnspectionregiven y:BS EN970 Non-destructivexamination f Fusionwelds - visual Examination)

1.2 BASICREQUIREMENTSORVISUAL NSPECTIONto BS ENe70)BS EN970Provideshe ollowing:u requirementsorweldingnspectionersonnelu recommendationsbout onditionsuitableor visual xaminationo theuseof gauges/inspectionids hatmaybe needed/helpfulor nspectionB guidance boutwhen nspection aybe required uring he stagesoffabricationa guidance bout nformationhatmayneed o be ncludedn the nspectionrecordsWeldingnsPectionRe v0 Ju n06Visual nspectionnd TypicalDuties fWeldingnsPectorsCopyright 2006,TWI Ltd

TWIwctWORLD CENTREFORMATERIALS JOININGTECHNOLOGY1 . 1


5/357

otr

A summary f eachof these opicss given n the ollowing ub-sections.

1.3 WELDINGNSPECTIONERSONNELBeforestartingwork on a particular ontract,BS 970 states hat WeldingInspectorshould:be familiarwith elevant tandards, rulesand specificat ionsor he abricationwork hat s to be undertaken(" standardsmaybe National r Client)be nformed bout hewelding rocedure(s)o be usedhavegoodvision in accordance ith EN473 & shouldbe checked very12monthsBS EN 970 does not give make any recommendationbout a formal

qualificationor visual nspectionf welds.However,t has become ndustry racticefor inspectorso have practical xperienceof welding nspectionogetherwith arecognised ualificationn Welding nspection suchas a CSWIPQualification.

1.4 CONDITIONSORVISUAL NSPECTIONl l luminat ionBS EN 970 states hat heminimumlluminationhallbe 350 ux but recommendsminimum f 500 ux..* normal shopor office ightingAccessAccess o the surface,or direct nspection,hould nable heeye:-o to bewithin 00mm f he surface eing nspectedu to be n a positiono givea viewing ngleof not ess han30"

Welding nspectionRev0 Jun 06Visual nspection ndTypicalDuties fWelding nspectorsCopyright@2006,TWI Ltd

T\MIW'1 . 2 WORLD CENTREFORMATERIALS JOININGTECHNOLOGY


6/357

1.5 AIDSTOVISUAL NSPECTIONWhereaccess s restrictedor directvisual nspection,he use of a mirroredboroscope, r a fibreopticviewing ystem, reoptionshatmaybe used usually yagreement etweenhe contracting arties'It may alsobe necessaryo provideauxiliaryightingo givesuitable ontrastand reliefefiectbetween urface mperfections nd he background'

other temsof equipmenthatmaybe appropriate,o facilitate isual xamination're:o welding auges(for checkingbevel anglesdePth)

and wetd profile, fittet sizing,measuringundercut

tr dedicated eld-gap augesand inearmisalignmenthigh-low)auges

o straight dgesandmeasuringapesu magnifYingens(ff iaSinificationensused o aid visuat xaminationt shouldbeX2 to X5)

BS g70hasschematics f a rangeof weldinggauges ogetherwithdetailsofwhat heycanbe used or and he precision f themeasurementshatcanbe made'

I . 6 S T A G E S W H E N I N S P E G T | o N M A Y B E R E Q U | R E DBS EN 970states hatexaminations normally erformed n welds

n the as-welded ondition.hismeans hatvisualnspectionf the inished eld s a minimumrequirement.

However, S EN 970 goes on to say that he extentof examination,nd thestages when some inspecti6nactivity s required,should be specifiedby thenff,ticatlon tandard r by agreement etweenClientand abricator'For fabricatedtems hat musthavehigh integrity',suchas pressure esselsandpiping r arge tructuresnspection ctivity ill usually e requiredhroughouthefabricationrocess, amelY.

u beforeweldingo during elding.tr afterweldinglnspectionactivities'at eachof thesestagesof fabricationan be consideredto be the dutiesof the welding inspector'and ypicalnspectionheckshatmayberequired redescribednthe ollowing ection'

WeldingnspectionRe v0 Ju n06Visual nspectionndTypical uties fWeldingnsPectorsCopyrightO 2006,TWILtd

TWIwfr WORLD CENTREFORMATER]ALS JOINTNGTECHNOLOGY1 . 3


7/357

1 . 7 T Y P | C A L D U T I E S o F A W E L D i N G | N S P E C T o RThe relevantstandards, ules and specificationshat a Welding lnspectorshould e amiliarwithat the startof a newcontract real l he docurnentse willneedto refer to during the fabrication equence n order to make judgementsaboutparticularetails.

Typical ocuments hatmayneed o be referredo are:o theApplication tandardorCode)(for v'isual cceptancecriteria see notebelow")o quality lansor inspectionheck ists(for the type& extentof inspection)o drawings(fo asiemb y/f it- p detais and d mensiona requ ements)o QC procedures

(Company C/QA Proceduresuchas fhose or- document ontrol,materialhandiing, lectrode torageand issue,WPSsetc)Note:Althoughmostof the requirementsor the fabricatedtem shouldbe specifiedbyNational taidards,CtientSfandardsr variousQCProcedures,ome eatures renot.easytodefineprecisetynd he equirement aybegivenas'toqoodworkmanshiptandard'.Examplesf requirementshatare difficulto defineprecisely re someshape olerances,distortion,surtace amage r theamount f weldspafter-'Goodworkmanship's the standardhat a competentworkershouldbe able to achievewithout ifficutty henusing hecorrect oolsn aparticular orking nvironment.ln practiceheappticationf the abricatedtemwillbe themain actor hat nfluences hat sjudgedto be good wod


8/357

Safetyconsciousness'is a dutyof allemployeesnd a Welding nspectorhould:B be awareof all safety egulationsor heworkplaceu ensurehatsafety quipmenthatwillbe neededs availabte nd nsuitablecondition

Duties Before WeldingCheckMaterial

{ , - T , - I " , n - . - r . | J , ,tJ'vY\/?tr- Jt/Ll-(t* l'L+'-vt \)Action J Iis n accordanceithdrawingAf/PSis identified canbe traced o a testcertificateis n suitable onditionfree romdamage& contamination)WpS,s havebeenapproved nd areavailableowelders &inspectors)WeldingEquipment is n suitable ondition nd calibrated s appropriateWeldPreparations are n accordanceithWPS (and/or rawings)

iWelder ualifications identificationfwelders ualifledor eachWPS o be usedal lwelder ualificationertificatesrevalid 'in-date')WeldingConsumables those o be usedareas specified y theWPSsarebeing' stored/controlleds specified y the QC ProcedureJointFit-ups , are n accordanceithwPS / Drawings' tackweldsare o goodworkmanshiptandard to

CodeA/VPSWeldFaceS ., , ,r" free romdefects, ontaminationnddamagePreheat if required) i min. emperatures n accordance ithWPS

DutiesDurinqWeldinqCheck Action

\ Site/fieldWelding ensureweather onditions re suitable/complyithCode(conditions il lnot affectwelding)

V WeldingProcess is n accordance ithWPSV' preheat if required) min. emp. s beingmaintainedn accordance ithWPS^/ lnl"r-pass emp max. emp. s n accordance ithWPSw

Weldingnspection 1.5Re v0 Jun06Visual nspectionndTypicalDuties fWelding nspectorsCopyright@2006,TWI Ltd

T\J[II woRLDcENTREFoRmnt MATERIALSJOININGVl///t rEcHNoLocY


9/357

weldingconsumables-' are n accordance ithwPS & being ontrolled s vProcedureWeldingparameters vr' current, olts, ravelspeed,are n accordance ithWPS .|/RootRun * isvisually cceptableo Code beforelllinghe oint) ld(for single rdedwelds)GougingGrinding ; is by anapprovedmethod& to goodworkmanshiptandard \"Inter-runleaning is to goodworkmanshiptandard a" rWelder is on theapproval egister/qualifiedor theWPS beingused !JDuties After WeldinqCheckWeld ldentification Y '-

Actioneachweld s markedwith hewelder'sdentiflcationeachweld s identifiedn accordance ithdrawing/weldmapensureweldsaresuitableor al lNDT proflle, leannessetc)visuallynspectweldsand sentencen accordance ithCodecheckdimensionsre n accordance ithDrawing/Codeensure nymodificationsre ncludedn'as-built 'rawingsensure ll NDT scomplete reports reavailableorrecordsmonitorn accordance ith heProceduremonitoror compliance ithProcedurecheck hart ecord)ensureestequipments calibratedmonitores t o ensure ompliance ithProcedure/Code, ensure eports/recordsreavailable

:1dt

WetdAppearanceV

Dimensional urveY :o V\".Vv

DrawingsNDTRepairsPWHT if required)Pressure/Loadest(i frequired)

\ , '

.Y

L"t .v

, i ,ut\lItt

iDocumentationecordsV-ensurell eports/recordsrecompletedcollateds

';required

Weldingnspection 1. 6Rev0 Jun06Visual nspectionndTypicalDuties fWeldingnspectorsCopyright@2006,TWI Ltd

TWIvcctORLD CENTREFORMATERIALS JOININGTECHNOLOGY

/4Ly 0-o4 +LtReeet i+l+L; ;-1::I


10/357

1.8 EXAMINATIONEGORDSTherequirementor examinationecords/inspectioneportswillvary accordingto contract nd ypeof fabricationnd here s frequently o requirementor a formalrecord.

Whenan inspectionecords requiredt may be necessaryo show hat temshave been checked at the specifiedstages and that they have satisfied heacceptanceriteria.The ormof this ecordwillvary possibly signature gainst n activity n anInspectionhecklist r on a Quality lan,or it maybe an ndividualnspectioneportfor each tem.

For ndividualnspectioneports, SEN970 ists ypical etailsor nclusionuchas:o nameof manufacturer/fabricatoru identiflcationf temexaminedo materialYPe& thicknesso typeof ointo weldingProcessa acceptancetandard/acceptanceriteriatr locations nd ypesof al l mperfectionsot acceptable(whenspecified,t maybe necessaryo includean accurate ketch r photo.)E nameof examiner/inspectornddateof examination

WeldingnspectionRe v0 Jun06Visual nspectionnd TypicalDuties fWeldingnsPectorsCopyright@2006,TWI Lt d

4 1t . I T\f,If woRLD cENTRE oRw[t [ffif;'.,?*^'


11/357

TWI woRLD ENTRE oRMATERIALS JOININCTECHNOLOGY

QuestionsResponsibilities and duties of a welding inspector

QU1. List 4 areas hat would generallybe coveredby a non-destructiveexamination NDE) nspectionstandard or welds?

QU2. List desirablecharacteristicshat all welding inspectorsshouldpossess?

QU3. List 5 areas of knowledge with which a proficient weldinginspector houldbe amiliarwith?

QU4. Give six main duties of a welding inspector before welding,duringweldingand afterwelding.

Welding inspectionRev 0 Jun06Copyright@2006,TWI Ltd Q U l


12/357


13/357

Section02Terms& Definitions

WeldingnspectionRev 0 Jun06CopyrightO 2006,TWILtdT1f,/f woRLD cENTRE oREinE MATEPJALSJOININGWUt rEcHNoLocY


14/357

2.A TERMSAND DEFINITIONSNote: The following efinitions re taken rom BS 499-1:1991Weldingtermsandsymbols Glossaryorwelding, razing nd hermal utting"Welding:An operationn which two or more parts are unitedby meansof heat orpressure r both, n such a way that there s continuityn the natureof the metalbetweenheseParts.Brazing:A processof joining generallyapplied o metals n which,duringor afterheating,molten illermetal s drawn nto or retained n the spacebetween loselyadjacent urfacesof the parts to be joined by capillaryattraction.n general, hemettingpoint of the filler metal is above 450"C but always below the meltingtemperaturef heparentmaterial.Brazewelding:The oiningof metalsusinga technique imilar o fusionweldingand a flllermetalwith a lowermeltingpoint han the parentmetal,but neitherusingcapillaryaction s n brazing or ntentionallyeltingheparentmetal.Weld:A unionof pieces f metalmadebywelding-Joint:

A connectionwhere the individualcomponents,suitably prepared andassembled,re oined ywelding r brazing'

Welding nspectionRe v0 Ju n06TermsandDefinitionsCopyright 2006,TWI Ltd

WORLD CENTREFORMATERIALS JOININGTECIINOLOGY

2.1 TWIw[t


15/357

A connection etween he endsor edgesof two Partsmakinganangle o one anotherof 135" to180' nclusiven theregion f the .,. lt i:,l=A connection etweenhe end oredge of one Partand the face ofthe other part, he Partsmakingan angle o one anotherof morethan5" up to and ncluding0" nthe region f the oint

a connectionetweenhe endsoredges of two Partsmaking anangle to one another of morethan30" but ess han135' n theregion f the oint

Corneroint

a connection etween he edgesof two partsmakingan angle ooneanother f 0" to 30" nclusivein the region f he ointEdgeoint

a connection n which two flatplatesor two barsare welded oanother lat plateat rightanglesandon hesame xis

Cruciformjoint

a connection between twooverlapping parts making anangle o one anotherof 0" to 5oinclusiven the region f theweldor welds2.2eldingnspectionRev0 Jun06TermsandDefinitionsCopyright 2006,TWILtd

TWIwctWORLD CENTREFORMATERIALS JOININGTECHNOLOGY


16/357

I 2.1 TYPESOFWELDS2.1.1 FROMCONFIGURATIONOINTOFVIEW

Butt weld Fil letweld

l--r-:: j

I1_Autogenous eld:A fusionweldmadewithoutillermetal.Canbe achieved nlyby TIGor Oxy-fuelgaswelding.Slotweld:A jointbetween wo overlappingomponentsround he periphery f a hole n onecomponentoother omponent xposedhroughhehole.

madeby dePositing fil letweldas to join t to the surfaceof the

Ina butt oint

In a T-ioint

Ina corneroint

2.3eldingnspectlonRev0 Ju n06Terms ndDefinitionsCopyright 2006,TWI LtdTWIwct WORLD CENTREFORMATERIALSJOININGTECF{NOLOGY


17/357

Plugweld:A weldmadeby fillinga hole n onecomponent f a workpiece ith illermetalso as to join t to the urfacEof an overlappingomponent xposedhroughhe hole(theholecanbe circular r oval).

2 .1 .2 FROMTHE PENETRATIONPOINTOF VIEWFull penetrationweld:A weldedointwhere he weldmetal ullypenetrateshe ointwithc_ompleteootfusion. /n US the preferred erm is completeoint penetrationweld or CJP for shori(seeAWSDl.1

Partialpenetrationweld:A welded oint without ull penetration.n US the preferred erm s partialointpenetrationweldor PJP for short.

o 2.2 TYPESOFJOINTS SEEBSEN SO15607)- homogeneousoint: welded oint n which he weld metaland parentmaterialhave no significantdifferences n mechanicalpropertiesand/or chemicalcomposition. xample:wo carbonsteelplatesweldedwith a matching arbonsteelelectrode.- heterogeneousoint: welded oint n which he weld metaland parentmaterialhavesignificant ifferencesn mechanical roperties nd/or hemical omposition.Example: repairweldof a cast ron temperformed itha nickel aseelectrode'- dissimilar joint: welded oint in which the parent materialshave significantdifferencesn mechanical roperties nd/orchemicalcomposition. xample:carbon teel iftingugweldedontoan austenitictainless teelpressure essel.

WeldingnspectionRe v0 Jun06TermsandDefinitionsCopyrightO 2006,TWILtd

2.4 TWIvffit WORLD CENTREFORMATERIALSJOININGTECFINOLOCY


18/357

2.3 FEATURES FTHEGOMPLETED ELD- parentmetal:metal o be oinedor surfaced ywelding, razewelding r brazing'- filler metal:metaladdedduringwelding, razewelding, razing r surfacing'- weld metal:al lmetalmelted uringhe making f a weldandretainedn theweld'- heat-affected one IHAZI'.he part of the parent metal that is metallurgicallyatfecteOy he heatof welding r hermal utting, ut not melted'- fusion line: he boundary etweenhe weldmetaland he HM in a fusionweld'This sa non-standarderm orweld unction'- weld zone: hezonecontainingheweldmetaland he HAZ.- weld face: he surface f a fusionweldexposed n the side romwhich he weldhasbeenmade.- root: hezoneon hesideof the irst un arthestrom hewelder'- toe: he boundary etween weld aceand he parentmetalor betweenuns.Thisis a very important eatureof a weld since toes are points of high stressconcentrationnd often heyare nitiation oints or differentypesof cracks e.9.fatigue racks, oldcracks).n order o reduce he stressconcentration,oesmustntenO moothlynto he parentmetal urface'- excessweldmetal:weldmetalying utsideheplaneoininghe oes.Other on-

standarderms or his eature:einforcement,verfill.

WeldingnspectionRe v0 Ju n06TermsandDefinitionsCopyright 2006, WI Ltd

2.5 T\III woRLD cENTRE oRWini MATEPTALSjoININGVlJlJ' TECHNOLOGY


19/357

Parentmetal

Fusionline

Parent

Excessweld metalExcessweldmetalParentmetal

Excessweldmetal

Fusionline

WeldmetalParentmetal

2.4 WELDPREPARATIONA preparationor making a connectionwhere the individual omponents,suitably repared nd assembled, re oinedbywelding r brazing.

WeldingnspectionRe v0 Jun06Termsand DefinitionsCopyright@2006,TWI Ltd

2.6 TWI y91t-9:TT.l?lwct ffiil};i'*-^"


20/357

2.4.1 FEATURES F THEWELDPREPARATIONangle of bevel: the angleat which he edge of a components prepared ormaking weld. n caseof a V preparationor a MMAweldon carbon teelplates,thisangle s 30'. In caseof a U preparationor a MMAweldon carbon teelplates,thisangle s between -12. Incaseof a singlebevelpreparationor a MMAweldon carbonsteelplates, his angle s 50". ln case of a singleJ preparationor aMMAweldon carbon teelplates,hisangle s between10-20".includedangle: he anglebetweenhe planesof the fusion acesof parts o bewelded.n caseof single , singleU,double anddoubleU thisangle s twice hebevelangle. n caseof singlebevel, ingleJ, doublebeveland doubleJ, theincludednglesequal o thebevel ngle.root face: he portionof a fusion aceat the root hat s not bevelled r grooved,It'svaluedepends n thewelding rocess sed,parentmaterialo be weldedandapplication;or a full penetration eld on carbon steel plates, t has a valuebetween -2mm.gap: he minimum istance t anycrosssection etween dges,endsor surfacesto be oined.ts valuedepends n hewelding rocess sedandapplication;or afullpenetration eldon carbon teelplates,t has a valuebetween -4mm.root radius: he radiusof the curvedportionof the fusion ace n a componentpreparedor a single , singleU, double or doubleU weld. n caseof MMA,MIGIMAG nd oxyfuel as welding n carbonsteelplates, he root radiushas avalueof 6mm n caseof single nd doubleU preparationsnd8 mm in caseofsingle nddouble preParations.land. the straightportionof a fusion ace between he root aceand the curvedpart of a J or U preparation. an be 0. Usuallypresent n case of weldpreparationsor MIGwelding f aluminiumlloys.

WeldingnspectionRev0 Jun06TermsandDefinitionsCopyright 2006, WI Ltd

TWIWf,' WORLD CENTREFORMATERIALS JOININGTECHNOLOGY2.7


21/357

2.4.2 TYPESOFPREPARATION

Opensquarebutt PreParation Thispreparations used or welding hin components,ither rom one sideorbothsides. t tne rootgap s zero i.e. f components re n contact),his preparationbecomesa closed squarebutt preparation unrecommendedue to the lack ofpenetrationroblems!

SingleV preparationTheV preparations oneof themostcommon reparationssed n welding;tcan be produced sing lameor plasma utting cheap nd ast).For hickerplatesadoubleV preparations preferred ince t requiresess illermaterialo completehejointand he residual tresses an be balanced n bothsidesof the oint resultingnlowerangular istortion.

DoubleV preparationThe depthof preparationan be the sameon bothsides symmetric oubleVpreparation)r the depthof preparationan be deeper n onesidecomparedwith heopposite ide asymmetricouble preparation).sually,n hissituationhe depthofpreparations distributed s 113of the thickness f the plateon one side vs. theremaining 13on the backside. his asymmetric reparation llows or a balancedWelding nspectionRe v0 Jun06Termsand DefinitionsCopyright@2006,TWI Ltd

2.8 T\MIWCTWORLD CENTRE FORMATEzuALS JOINI^-GTECHNOLOGY

Angleof


22/357

welding equence ith root backgouging, iving owerangular istortions. hilstsingleV preparationllowswelding romone side,doubleV preparationequires othsidesaccess thesameappliesor all double idepreparations).Included ngle

Rootface

SingleU preparationU preparationan be produced nly by machiningslow and expensive).However,ighterolerancesbtainedn thiscaseprovideor a bet ter it-up han n thecaseof V preparations.suallyt is appliedor hicker lates ompared ithsinglepreparationrequiresess illermaterial o completehe oint and this lead o lowerresidual tresses nddistortions).imilarwith heV preparation,n caseof very hicksections doubleU preparationanbe used-

DoubleU preparationUsuallyhis ypeof preparationoesalloys). not equire landexception.luminium

Welding nspectionRev 0 Jun 06Termsand DefinitionsCopyrightO 2006,TWI Ltd

T\MI WORLD CENTREFORMATERIALSJOININGTECHNOLOGY

2.9 WI


23/357

SingleV preparationwith backingstripThe backingstrip s made out of the same type of materialas the parentmaterial. he hickness f thisbacking trip s minimum mm. t allows heproductionof full penetration elds with increased urrentand hence increased epositionrates/productivityithout hedanger f burn-through.sually,he backing trip s tackweldedon the backside f one component singa fillet weld. The mainproblemsrelatedwith his ypeof weldare poor atigue esistance nd he probabilityf crevicecorrosion etweenhe parentmetaland hebacking trip. t is alsodifficulto examineby NDTdue o the built-in revice t therootof the oint.Note hat n thiscase here sno root ace!

Singlebevelpreparation

Doublebevelpreparation

2 . 1 0elding nspectionRev0 Jun06TermsandDefinitionsCopyrightO 2006,TWI LtdTWIvcfltWORLD CENTREFORMATERIALSJOININGTECHNOLOGY


24/357

Single preparation

Double preparationAll hesepreparationssingle/doubleevelandsingle/double) can be usedonT jointsas well.Doublepreparationsre recommendedn caseof thicksections. hemainadvantagef thesepreparationss thatonlyonecomponents preparedcheap,

canallow orsmallmisalignments).For further etails egarding eld preparations,lease efer o BS EN ISO9692 tandard.

2.5 SIZEOF BUTTWELDS- fullpenetrationut tweld

Actualthroatthickness Design hroatthickness

2 . 1 1eldingnspectionRe v0 Jun06Terms ndDefinitionsCopyright 2006, WI Ltd

TWIv[crWORLD CENTRE FORMATERIALS JOININGTECHNOLOGY


25/357

partial enetrationut tweld

ActualthroatthicknessDesign hroatthickness

As a general ule:

- fullpenetrationut tweldgroundlush

- buttweldbetween wo platesof differenthickness

Actual hroat hickness= Designhroatthickness

Actual hroat hicknessMaximumhicknessthroughhe ointDesignhroathickness= Thicknessf hethinner late

Run (pass): he metalmelted r deposited uringone passage f an electrode,orchorblowpipe.

Singleunweld Multi unweldLayer:a stratum f weldmetal onsistingf one or more uns

2 . 1 2eldingnspectionRev0 Jun06TermsandDefinitionsCopyright 2006,TWI LtdT\nIIW' WORLD CENTREFORIVIATERIALSJOININGTECHNOLOGY


26/357

Typesof butt weld (fromaccessibility oint of view):

2.6 FILLETWELDA fusion weld, other than a butt, edge or fusion spot weld, which isapproximatelyriangularn transverserosssection.

2 .6 .1 SIZEOFFILLETWELDSUnlike uttwelds, il letwelds anbedefined sing everal imensions.- actuat hroat thickness: he perpendicularistance etween wo lines,eachparallelo a line oining heouter oes,onebeinga tangent t the weld aceandthe otherbeing hroughhe urthermostointof usion enetration- design hroat hickness:he minimum imensionf throat hickness sed orpurposes f design.Also knownas effectivehroat hickness. ymbolised nthedrawing ith a".

leg length: he distancerom he actualor projectedntersectionfacesand he toeof a filletweld,measured cross he usion ace.on he drawingwith 2" .

Le glength

of the fusionSymbolised

Actualthroatthickness,y ' t

Singlesideweld Double ideweld

2 . 1 3elding nspectionRev 0 Jun 06Termsand DefinitionsCopyright@ 2006, TWI Ltd

TwIwflt WORLD CENTRE FORMATERIALSJOININGTECHNOLOGY


27/357

2.6.2 SI-IAPE FFILLETWELDS- mitrefillet weld:a flat ace illetweld n which he eg engths reequalwithin heagreedolerance. he cross ection reaof this ypeof weld s consideredo be arilht angle soscelesriangle itha design hroat hicknessa"and a leg ength 2" .Therelation etween esignhroat hickness nd eg engths:

a = 0 . 7 0 7 z . orW,q,.a1-^7

convex fillet weld: a filletweld in which the weld face is convex.The aboverelation etweenhe eg engthand the design hroat hickness ritten n caseofmitre illetwelds s alsovalid or this type of weld.Since here s an excessweldmetalpresentn this case, he actual hroat hicknesss bigger han he designthroat hickness.Excess weld

a designthroatconcave illet weld: a filletweld in which he weld ace s concave. he aboverelation etweenhe leg engthand the design hroat hickness rittenn caseofmitre illetwelds s not anymore alid or this ypeof weld.Also, he design hroatthicknesss equal o ihe actual hroat hickness.Due to the smoothblendingbetween the weld face and the surroundingparent material, the stressconcentrationffectat the oesof theweld s reduced ompared ith heprevioustype. This is why this type of weld is highly desired n case of applicationssubjectedo cyclic oadswhere atiguephenomenamightbe a majorcause orfailure.

WeldingnspectionRev0 Jun06TermsandDefinitionsCopyrightO 2006,TWILtdTWIwct WORLDCENTREFORMATENALS JOINTNCTECHNOLOGY2 . 1 4


28/357

Design

asymmetrical illet weld: a filletweld n which he vertical eg ength s not equalwith he horizontaleg ength. Therelation etweenhe eg engthand he designthroai hicknesswritten n case of mitre illetwelds s not anymore alid or thistypeof weldbecausehecrosssections notanymore n soscelesriangle.

Verticalleg sizeThroatsize

deeppenetration illetweld: a filletweldwitha deeper hannormalpenetration.tis produced singhighheat nputwelding rocessesi.e.SAW or MAGwithspraytransfer). his ype of weld uses he benefits f greater rc penetrationo obtainthe required hroat thicknesswhilst reducing he amount of depositedmetalneeded,hus eading o a reductionn residual tress evel. n order o produceconsistent nd constant enetration,he travelspeedmust be kept constant, t ahigh value.As a consequence,his type of weld is usuallyproduced singmechanisedr automatic elding rocesses. lso, he highdepth-to-widthatioincreases the probabilityof solidification entrelinecracking. ln order todifferentiatehis type of welds from the previousypes, he throat hicknessssymbolised ith s"instead f "a".

WeldingnspectionRe v0 Jun06Termsand DefinitionsCopyright 2006,TWI Ltd

T\MIw[t WORLD CENTREFORMATERIALS JOININGTEC}INOLOCY

Horizontal

2 .1 5


29/357

A combinationf buttand illetweldsused n caseof T jointswith ul lor partialpenetration r butt oints between wo plateswith different hickness. illetwelds"OO"O n top of the groovewelds mprovehe blending f weld ace owardsparentmetal urface ndreducehe stress oncentrationt the oesof theweld.

2.6.3 COMPOUND FBUTTANDFILLETWELDS

Double evel omPound eld

2.7 WELDING POSITION,WELD SLOPE AND WELDROTATIONWeldposition the orientationf a weldexpressedn termsof working osition, eldslopeandweld otationfor urther etails, lease ee ISO6947).Weld slope -the anglebetween oot ine and the positiveX-axisof the horizontalreferenceplane, measured in mathematically ositive direction(i e. counter-clockwise).

Wefd rotation the anglebetweenhe centreline f theweldand he positive -axisor a lineparallelo theY-axis,measuredn the mathematicallyositive irectioni.e.counter-clockwise)n the planeof the ransverserosssection f theweld n question.

WeldingnspectionRev0 Jun06Terms ndDefinitionsCopyright@2006,TWI LtdTWIw[r WORLD CENTM FORMATERIALSJOININGTECHNOLOGY

. : :

2 , 1 6


30/357

Weldingoosition Sketch DefinitionFlat a weldingpositionn whichthe welding s horizontal,with the centreline f theweld vertical. SymbolaccordinqSO6947 PA.Horizontal-vertical a weldingpositionn whichthe welding is horizontal(applicablen case of fi l letwelds). Symbol accordinglso 6947 PB

Horizontal a welding ositionn whichthe welding s horizontal,with the centreline f theweld horizontal.SymbolaccordingSO6947 PC

Vertical p a welding ositionn whichthe welding is upwards.Symbol according ISO6947 PF.Vertical own a welding ositionn whichthe welding s downwards.Symbol according ISO6947 PG

Overhead a welding ositionn whichthe welding is horizontaland overhead,with thecentreline of the weldvertical,Symbolaccordinglso 6947 PE.Horizontal-overhead \ a welding ositionn whichthe welding is horizontaland overhead applicablein case of fillet welds).Symbol according ISO6947 PD.2 .1 7eldingnspectionRev0 Jun06Terms nd Definitions

Copyright 2006, WI Ltd

TWI woRLDcENTREFoRvcflf ffiy"f;';^^


31/357

10 " 10 "[+ji i iii i_-s0:___qojiIIi 180"Rotation

Ve{ical-up90"l0 ' l0 'i- J-:r' i . , i

i=. I E-r' t E i E ti liifi' lFiiFY i rii i

0 e - . r , . 0 oSlope

Overl teat i

fe rtic* i-ti +.'i,g0'l0 ' '10"

i- l' 'l! i tRotation0-180n iboth cases

.\ I --r, tr i . i i i!. i i f i i 'q l

LlrJr i ,

1io;i 6 r'r-ai r*nicel

i: o.Slope

,-115"90" i ' 90"+-* I ; - - i .! ;- 75,",'r6o"Rotation

30' 30",*.-T\i ' " ' . i ' \so'n{ :t- - i*go"\ i i\-.r'-'180"Rotation_gn---,:i#)i:""****,*i!1"

Slope

Tolerances or the welding positions

2.8 WEAVINGTransversescillationf an electrode r of a blowpipe ozzle uring he deposition fweldmetal. his echniquesgenerallysed n caseofvertical pwelds'

Stringerbead:a runof weldmetalmadewith ittleor noweavingmotion.

Slope

WeldingnspectionRev0 Jun 06Termsand DefinitionsCopyright@2006,TWI LtdT\ilI WORLD CENTREFORMATEzuALSJOINING

TECHNOLOGY2 . 1 8 V[Tf


32/357

TWI woRLD ENTRE oRFffi&l'f.lf#i"J#rNrNcQuestions

QU1.

QU2.

TerminologySketcha single U butt joint and indicate he fotlowing:a) Root ace. b) Rootgap.c) ncluded ngle.d) Root adius.

Sketcha tee oint, fillet weldedwith deeppenetrationandindicate he following:a) leg ength. b) Design hroat hickness. c) Root. d) Weld oes.

QU3. Complete he necessary eaturesof the sketch:

QU4. Sketch hree oint types in addition o a butt weld:

Welding inspectionRev 0 Jun 06Copyright @ 2006,TWILtd Q U 2


33/357

Section03Welding mperfections

WeldingnspectionRe v0 Jun06CopyrightO 2006,TWI LtdT\f,/I woRLD cENTRE oR;;;- MATERIALS OININGWUt rEc'NotocY


34/357

3.0 WELDINGIMPERFECTIONS3.1 DEF!NIT IONSDefinitions seeBS EN ISO6520'1)lmperfection: nydeviationrom he dealweld.Defect: n unacceptablemperfection.Classification f imperfectionsaccording o BS EN ISO6520-{:

This standard lassifieshe geometric mperfectionsn case of fusionwelding,dividinghem ntosixgrouPs:1) Cracks2) Cavities3) Solidnclusions4) Lackof fusion ndPenetration5) lmperfecthape nddimension6) MiscellaneousmPerfections

It s mportanthatan mperfections correctlydentifiedhusallowingor hecauseto be dentifiedndactionsaken o preventurther ccurrence.

3.2 CRACKSDefinition:an imperfectionroduced y a local upturen the solidstate,whichmayarise rom the effectof coolingor stresses.Cracksare more significanthan othertypesof imperfection,s theirgeometry roduces very argestress oncentrationtthecrack ip,makinghemmore ikely o cause racture.Typesof cracks:

longitudinalrackstransverseracksradiatingracks cracks adiatingroma common oint)crater racksbranchingracks a groupof connectedracks riginatingroma common rack)These racks anbe situated:- in heweldmetal- in heHM- in heparentmetalException: rater racksare oundonly n theweldmetal.

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright 2006,TWILtd

3.1 TWIwflt WORLD CENTRE FORMATERIALS JOININGTECHNOLOGY


35/357

Dependingn theirnature,hese racks an be '- hotcracks i.e.solidificationracksiquation racks)- precipitationnduced racks i.e. eheat racks, resentn creep esistingteels)- coldcracks i.e.hydrogennduced racks)- lamellarearing

3.2.1 HOTCRACKSDependingn their ocation ndmodeof occurrence,ot cracks anbe:- solidificationracks:occur n the weld metal(usually long he centreline f theweld)as a result f thesolidificationrocess- iiquitioncracks:occur n the coarsegrainHAZ, n the nearvicinity f the fusionlineas a resultof heatinghe materialo an elevatedemperature,ighenoughofroduce iquation f the 6wmelting ointconstituentslaced ngrainboundaries.

3.2.2 SOLTDIFICATIONRACKS

20mmGenerally,olidificationrackinganoccurwhen:

. theweldmetalhasa highcarbonor impuritysulphur tc)elementcontent. thedepthto-widthatioof thesolidifying eldbead s arge deep&narrow)

. disruption f theheat lowcondition ccurs, .g .stop/startonditionThe crackscan be wideand open o the surfaceikeshrinkage oidsor sub-surface nd possiblYarrow.Solidificationrackings most ikely o occur n compositions,hich esultn awide reezingemperatureange. n steels his s commonly reateclbythigher than

WeldingnspectionRe v0 Jun06WeldingmperfectionsCopyright@2006,TWILtd

T\I/f woRLDcENTREFoRWini MATERIALSToININGWJIJ' TECHNOLOGY

3.2


36/357

normalcontentof carbonand impurityelements uchas sulphurand phosphorus.These elementssegregate uringsolidification,o that intergranulariquid filmsremainafter he bulkof the weld has solidified. he thermal hrinkage f the coolingweldbeadcancause hese o rupture nd orma crack.

It is importanthat the welding abricator oes not weld on or near metalsurfaces overedwith scaleor which have been contaminated ith oil or grease.Scale an havea highsulphur ontent, nd oil andgrease an supplybothcarbonandsulphur.Contaminationith ow melting ointmetals uchas copper,in, ead,andzincshould lsobeavoided.

HYDROGENNDUCED RACKS

Hydrogennduced racking ccursprimarilyn the grain-coarsenedegionofthe HAZ, and is also knownas cold cracking, elayedcrackingor underbeaditoecracking.Underbead racking ies parallel o the fusionboundary, nd its path isusually combinationf ntergranularnd ransgranularracking.hedirection f theprincipal esidual ensilestresscan, for toe cracks,cause he crack path to growprogressivelyway rom he fusionboundaryowards regionof lowersensitivityoWeldingnspectionRe v0 Ju n 06WeldingmperfectionsCopyright@2006,TWI Ltd

TWI y::_"::IT:?lv[cr ffi;*^^"

Sulp ur-enr ichedliquid i lnt - Solidif icationcrack

Shrinkagestrain

Toe crack

3.3


37/357

hydrogencracking.When this happens, he crack growth rate decreasesandeventually rrests.A combinationf three actorss necessaryo causeHM hydrogen racking.

ln addition,he weldmustcooldown o nearnormalambient emperature, herethe effectof hydrogens at its maximum.f anyone actor s not satisfied,rackingspreventeo. heref6re, rackingcan be avoided hroughcontrolof one or more ofthese actors.- ' , ./ . 1

a

f\ . J{ " J o l

r-uv ' '

applypreheat tg_.s_law_ow4 the qoo-linq,raiend thus avoid he formationofsuscgplible m1qgqtiuc-tdrirainiain sgeglllglplejpgssempe.rqtgr.gsameeffectas preheat)postheat r,[o'fiirfiiiion t welding toreducehe hydrogen ontent y allowinghydrogenoeffuserom heweldarea)apply PWHT (to rgduc.ere..sidual.g-lr,e.igmicrostructur-es) and eliminat_e,uscePtible

ieduie weld metal hydrogen by properprocessiconsumablee.g.use TIG weldingnsteadelectrodesnstead ellulose nes)use multi-run instead single-run technique (eliminate susceptiblemicrostructuresymeansof self empering ffect, educehe hydrogen ontentby allowing ydrogeno effuse rom heweldarea)ui " " temper eador hotpass echniquesame ffectas above)use austenitic r nickel iller(avoidsusceptible icrostructureormation ndallowhydrogen iffusion ut of critical reas)usedryshielding ases reduce ydrogenontent)clean oint rom rust (avoidhydrogen ontaminationrom moisture resent ntherust)reduce esidual tressblend heweldprofile reduce tress oncentrationt he oesof theweld)

selection of weldingMMA,use basiccovered

aa

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright@2006,TWI Ltd

3.4 TWIwctWORLD CENTREFORMATERIALSJOININGTECHNOLOGY


38/357

Lamellarearingoccursonly n rolledsteelproducts primarily lates)and itsmaindistinguishingeatures that hecracking asa terraced ppearance'Cracking ccursn ointswhere.o ? thermal ontraction trainoccurs n the ihrough hickness irection f steel

3.2.4 LAMELLAR EARING

very thin platelets,with their principal

Contraction train mPosed nthe planar non-metallicnclusionsresults n progressive ecohesionoform the roughly rectangular oleswhich are the horizontal artsof thecracking, arallelo the platesurface.With urther train,hevertical artsofthe crackingare produced, enerallyby ductileshearcracking' hese wostagescreate he terracedappearance f thesecracks.Twomainoptions reavailableo controlhe problem n weldedoints iable olamellarearing:

o usa clean ieelwithguaranteedhroughthicknessropertiesZgrade)o ? combinationf ointdesign,estraintontrol ndwelding equenceominimisehe iskof cracking'

plateo non-metallicnclusions re present splanes arallelo theplate urface

WeldingnsPectionRe v0 Ju n06WeldingmperfectionsCopyright@2006, WI Lt d

? 6 '|-Il/f woRLDCENTREoRAint MATERTALSoININGVIJlJt rEclINoLoGY


39/357

3.3 CAVITIES

3.3.1 GAS PORE

20mnrDescriptionA gascavityof essentiallypherical hape rappedwithin heweldmetal.Thisgascavity an be present nvarious orms:- isolated- uniformly istributedorosity- clusteredlocalised) orosity

Gascavity: ormedby entrapped as Shrinkage avity:causedby shrinkageduringsolidification

lnterdendriticshrinkage

Clustered(localised) orosity

Welding nspectionRe v0 Jun06Welding mperfectionsCopyright 2006,TWI Ltd

3.6 T\[/I woRLDcENTREFoRwctm##;^^"


40/357

- linear orosity- elongatedavity- surface oreGauses PreventionDamp luxes/corrodedlectrode(MMA) Usedry electrodesn goodconditionG ease/hydoca bon/watercontaminationf prepared urface Clean

prepared urfaceAir entrapmentn gasshield(MIG/MAGIG) CheckhoseconnectionsIncorrecVisufficient eoxidantnelectrode,llleror Parentmetal

Useelectrodewith sufficientdeoxidationctivitvToo hiqhan arc voltaqeor arc length Reduce oltage ndarc engthGasevolutionromPrimingpaints/surfacereatment ldentify iskof reaction efore urfacetreatments appliedToohighof a shielding as low atewhich esultsn turbulenceMlG/MAGTIG)

Optimise as low ate

GommentsNote hatporosity an eitherbe localisedor finelydispersedvoids hroughoutheweldmetal.

3.3.2 WORMHOLES

DescriptionElongatedr ubular avitiesormed y entrapped as during hesolidificationf theweldmetal;heycanoccur ingly r ngroups.

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright@2006,TWI LtdTWIwfit WORLD CENTREFORMATERIALS JOININGTECHNOLOGY3.7


41/357


42/357

GommentsTheorigins f surface orosity resimilaro those or uniform orosity.

3.3.4 CRATERPIPE

DescriptionA shrinkage avityat the end of a weld run. The main cause s shrinkage uringsolidification.

GommentsCrater illing s a particular roblemn TIGwelding ue to its owheat nput.To fill hecrater or hisprocesst is necessaryo reduce heweld current slope ut) n a seriesof descendingtepsuntil he arc is extinguished.

WeldingnspectionRev0 Jun06Welding mperfectionsCopyright@2006,TWILtd

3.9

i.t!ai--r-r20mm

Causes PreventionLackofwelder kill ue o usingprocesses ith oo higha current Retrain elderInoperativerater iller Slope ut )(TrG)

Usecorrect rater illingechniques

TWI woRLD ENTREoRwct ffi#;'f^ "


43/357

3.4 SOL!D NCLUSIONSDefinition:Solid oreign ubstancesntrappedn theweldmetal'

3.4.1 SLAG NCLUSIONS

DescriptionSlagkappedduringwelding. he mperfections of an irregular hapeand husdiffersin appearanceroma gasPore.

Welding nspectionRe v0 Jun06WeldingmperfectionsCopyright 2006,TWILtd

WORLDCENTREFORMATERIALS JOININGTECHNOLOGY

3 . 1 0 TWIwcr


44/357

Causes Preventionlncomplete slag removal fromunderlvinqurface f multipass eld lmproventer-run lag emoval

Slag looding headof arc Position ork to gaincontrol f slag'Welderneeds o correctelectrode ngle-Entrapment f slag n worksqrfqgg Dressworksurfacesmoothi:il|;:nrsion of nctusionsaybepresent ithin.theeldmetal, articularlvf theMMAprocesss used.Theseonlybecome problem hen argeor sharp-edgedinclusionsreProduced.3.4.2 FLUX NCLUSIONS

DescriptionFlux rapped uringwelding. he mperfections of an irregular hapeand husdiffersin appearancerolma gal pore.Appearonly in case of flux associatedweldingprocessesi.e.MMA,SAWandFCAW).Gauses PreventionUnfusedlux due o darlqgsq rgg$g- Useelectrodesn qoodconditionFlux fails to melt and becomestrappedn theweld SAWor FCAW)

Change the flux/wire. Ad1ust welolngpararneters .e. current, voltage etc tooroduce atisfactorvelding onditions

DescriptionOxides rappedduringwelding.The imperfectiondiffersnappearanceroma gaspore.

3.4.3 OXIDE NCLUSIONS

CommentsA specialypeof oxide nclusionthe case of aluminium lloYs.combinationof unsatisfactoryturbulencen heweldPool.

is of an irregular haPeand thus

Gauses PreventionHeavvmillscale/rustn worksurface Grind urface rior o welding

is puckering. his ype of defectoccurs speciallynGrossoxide film enfoldment an occur due to aprotection rom atmosphericcontamination nd

3 . 1 1elding nspectionRe v 0 Jun 06Welding mPerfectionsCopyright@2006, TWI Ltd

TWIvflctWORLD CENTRE FORMATERIALS JOININGTECHNOLOGY


45/357

3.4.4 TUNGSTENNCLUSIONS

DescriptionParticles f tungsten an becomeembedded uringTIG welding. his mperfectionappears s a lightareaon radiographsue o the act hat ungstens denserhan hesuirounding etal ndabsorbsarger mounts f X/gamma adiation'

Keep tungstenou t of weld Pool;useContact f electrodeip withweldpoolnvoiOcontactbetweenelectrodeandContact of filler metal with hot tip ofReduce welding current; adjustshieldinq as low ateontamination

f the electrode tip byReduce welding current; rePlaceelectrode itha larger iameternexceeding he current imit for a givenelectrodeizeor Reduce electrodeextensionand/orwelding urrentExtension f electrode eyond he normaldistance from the collet, resulting in

Adjust the shieldinggas flow rate;protect he weldarea;ensure hat thepost gas flow after stoPPinghe arccontinuesor at east5 secondslnadequateshieldinggas flow rate orexcessive inddrafts esultingn oxidationof theelectrodeiP

ehange the electrode,ensure thecorrect ize ungstens selectedor heivenweldinq urrent sedSpliisor cracksn theelectrode

Changeo correct ascomPositionlnadequate hieldinggas (eg'argon-oxygenor argon-carbonuseofdioxidemixtureshatareused or MAGwel

WeldingnsPectionRe v0 Jun06WeldingmperfectionsCopyrightO 2006,TWILtd

3 .12 '|.IIn woRLDcENTREFoRHnE MATERIALSotNINcV1f1/, rEcl'No'-oc'


46/357

3.5 LACKOFFUSION NDPENETRATION3.5.1 LACKOFFUSIONDefinition:Lack of union between he weld metal and the parent metal or

WeldingnsPectionRev0 Jun06WeldingmPerfectionsCopyright@2006,TWILtd

successiveaYers fweldmetal.

3 .5 .1 .1 LACKOFSIDEWALL USION

DescriptionLackof unionbetweenheweldandparentmetalat oneor bothsidesof the weld'

between the

WORLD CENTREFORMATERIALS JOININGTECHNOLOGY

TWIwct

iilrease arcvoltage nd/orwelding urrent;decreaseravelLowheat nput oweld mproveetectrodengleandworkposition;increaseravelvtotten etal looding head f arc tmprove dgepreparationrocedureOxideor scaleonweldPreParation Reducenductance,ven f this ncreasesExcessivenductancenMAGdiPtransferweldi 3 .13


47/357

CommentsDuringweldingsufficient eat must be available t the edge of the weld pool toproduceusionwith he parentmetal'

3.5.1.2 LACKOF NTER.RUNUSION

DescriptionA lackof unionalong he usionine,betweenheweldbeads

CommentsLackof inter-runusionproduce revices etween he weld beadsand cause ocalentrapmentf slag.

WeldingnspectionRe v0 Jun 06Welding mperfectionsCopyright@2006,TWI LtdT\MIvcrtWORLD CENTREFORMATERIALS JOININGTECFINOLOGY

Causes PreventionLowarccurrentesultingn owfluiditv f weldpool lncrease urrentToo hiqha travel Peed Reduceravel peedInaccurate eadplacement Retrain elder

3.14


48/357

3.5 .1 .3 LACKOF ROOTFUSION

DescriptionLackof fusion etweenheweldandparentmetalat therootof a weld.

3.5.2 LACKOFPENETRATION

Causes PreventionLowheat nput lncreasewelding urrent nd/or rcvoltage;decreaseravelspeedExcessivenductancen MAGdiptransfer elding, Usecorrectnduction ettingor he

parentmetal hicknessMMAelectrodeoo arge lowcurrentdensitv) Reduce lectrode izeUseof vertical ownweldinq Switch o vertical pprocedureLarqe oot ace Reduce oot aceSmall ootqap Ensure orrect ootopeninqIncorrect ngleor incorrect lectrodemanioulation Usecorrect lectrode ngle.Ensurewelderis fullvqualified ndcompetent

Excessive isaliqnmentt root Ensure orrect liqnment

3 .1 5eldingnspectionRe v0 Jun06WeldingmperfectionsCopyright@2006,TWI Ltd

TWIWC' WORLD CENTREFORMATERIALS JOININGTECHNOLOGY


49/357

3.5.2.1 TNGOMPLETEENETRATION

DescriptionThedifference etweentheactual ndnominal enetration.

Gommentslf theweld oint s notof a critical ature,.e. he required trengths low and he areais notprone o fatigue racking,t is possibleo produce partial enetration eld. nthiscase ncompleteootpenetrations considered ar tof thisstructure nd s not animperfectionthiswouldnormally edeterminedy he design r code equirement).

WeldingnspectionRe v0 Jun06Welding mperfectionsCopyright@2006,TWI Ltd

l*20mm

Gauses PreventionExcessivelyhick oot ace,insufficientootgapor failureo cutback o soundmetal n a "backoouoinq"peration

lmprove ackgougingechnique ndensurehe edgepreparations as perapprovedWPSLowheat nput lncrease elding urrent nd/or rcvoltage;decreaseravel peedExcessivenductancen MAGdiPtransfer elding, ool loodingheadof arc

lmprove lectricalettings ndpossiblyswitcho sprayarc ransferMMAelectrodeoo arge lowcurrentdensitv) Reduce lectrode izeUseof vertical ownwelding Switch o verticalup procedure

3 . 1 6 TWI woRLDcENTMFoRwct ffil;i'*'


50/357

3.5.2.2 INCOMPLETE OOTFUSION

DescriptionOne or both usion acesof the root are not melted.Whenexaminedromside, oucanclearly ee oneor bothof the rootedgesunmelted.Causes ndpreventionSameas for ackof rootpenetration

the root

3 .1 7eldingnspectionRe v0 Jun06Welding mperfectionsCopyright@2006,TWI LtdTWIwflt WORLDCENTREFORMATERIALS JOININGTECHNOLOGY


51/357

3.6 IMPERFECTHAPE NDDIMENSIONS3.6.1 UNDERCUT

DescriptionAn irregular rooveat the oe of a run n theweldmetaldue o welding.t is characterisedparentmetalor in a previouslyepositedby tsdepth,ength ndsharpness.

Intermittentundercut

-Z$rnm

Causes PreventionMelting f opedgedue o highweldingcurrent especiallyt freeedge)or hightravel peedReduce ower nput, speciallyapproaching freeedgewhereoverheatinganoccurAttempting filletweld n horizontalvertical ositionPB)with eglength>9mmWeld n the lat position r usemultiruntechniques

Excessive/i correctweaving Reduceweavingwidthor switchomultirunslncorrect lectrode ngle Direct rc owardshickermemberIncorrecthieldingasselectionMAG) Ensure orrect asmixtureor materialtypeand hickness MAG)

3 . 1 8eldingnspectionRev0 Jun06WeldingmperfectionsCopyrightO 2006,TWI LtdTWIwcrWORLD CENTRE FORMATEzuALSJOININGTECHNOLOGY


52/357

CommentsCaremustbe takenduringweld repairs f undercuto control heheat nput. f thebeadof a repairweld s too small, he cooling ate ollowing eldingwillbe excessiveand the parent metal may have an increasedhardnessand the weld may besusceptibleo hydrogen racking.

3.6.2 EXGESSWELDMETAL

DescriptionExcessweldmetal s the extrametal hatproduces xcessive onvexityn filletweldsand a weld hickness reaterhan he parentmetalplate n buttwelds.This eatureofa weld s regarded s an imperfectionnlywhen he height f the excessweldmetalisgreaterhana specifiedimit.

CommentsThe term "reinforcement"used o designatehis featureof the weld is misleadingsince he excessmetaldoesnot normally roducea strongerweld n a butt oint nordinary teel.This mperfectionan becomea problem, s the angleof the weld oecan be sharp,eading o an ncreased tressconcentrationt the oesof theweldandfatigue racking.WeldingnspectionRe v0 Jun06WeldingmperfectionsCopyright@2006,TWI Ltd

TwI y9=:.:.Ty:?lwct ffiof.l'f*"

-.--$Omm

Gauses PreventionExcess rcenerqv MAG,SAW) Reduction f heat noutShallow dqeoreoaration Deepen dqepreparationFaulty electrode manipulationorbuild-upequence lmprove elder kil lIncorrect lectrode ize Reduce lectrode izeTooslowa travel peed Ensure orrect ravel peed s usedIncorrectelectrodeanqle Ensurecorrectelectrode nqle s usedWrong polarity used (Electrodepolaritv C-VE

Ensure orrect olarity.e.DC+VE

3 . 1 9


53/357

3.6.3 EXCESS ENETRATION

DescriptionProjection f the root penetration ead beyonda specified imit can be local orcontinuous.Gauses PreventionWeldheat nput oo high Reduce rcvoltage nd/orwelding urrent;increase eldinq peedIncorrect eldpreparation.e.excessiveootgap, hinedgepreparation,ackof backing

lmprove orkpiece reparation

Useof electrodensuitedo weldingoosition Usecorrectelectrodeor positionLackof welder kill Retrain elderCommentsNote hat hemaintenancef a penetrationeadhavinguniform imensionsequiresa greatdealof skill,particularlyn pipebuttwelding. hiscan be mademoredifficultfthere s restr icted ccess o the weldor a narrow reparation.he use of permanentor temporary acking arscan be used o assistn the control f penetration.

Welding nspectionRev0 Jun06WeldingmperfectionsCopyrightO 2006,TWILtdTWIwflt WORLD CENTRE FORMATERIALS JOININGTECHNOLOGY3.20


54/357

3.6.4 OVERLAP

DescriptionAn imperfection t the toe of a weld causedby metal lowingon to the surfaceof theparentmetalwithoutusingo t.

Causes PreventionPoorelectrodemanipulationMMA) Retrain elderHighheat npuUlowravel Peedcausinq urfacelowof filletwelds Reduce eat nputor limitsizeof filletweldto9mm eqbv usinqmultirun eld

Incorrect ositioninqf weld Chanqeo flatpositionWrongElectrode oatingYPeresultingn toohigha fluiditY Change lectrodeoatingype o a moresuitableast reezingypewhich s essfluid

CommentsFor a filletweld overlap s oftenassociated ith undercut, s if the weldpool s toofluid he top of the weldwill low away o produce ndercut t the top andoverlap tthe base. lf the volumeof the weld pool is too large in case of a filletweld inhorizontal-verticalosition PB),weld metalwill collapsedue to gravity,producingboth defects undercut t the top and overlapat the base).This defect s called"sagging".

TWIeldingnspectionRev0 Ju n06WeldingmperfectionsCopyright@2006,TWI Ltd


-20mln

3 .21 VICT


55/357

3.6.5 LINEARMISALIGNMENT

DescriptionMisalignmentetween wo weldedpiecessuch that while heir surfaceplanesareparallel,heyarenot n therequired ameplane'

Gauses Preventionlnaccuraciesn assemblYproceduresr distortionromotherweldsAdequate hecking f alignment rior owelding oupledwith he useof clamps ndwedoesExcessiveoutof flatness'nhotrolled lates r sections Checkaccuracy f rolled ection

rior oweldinqGommentsMisalignments not reallya weld mperfection,ut a structural reparation roblem,Even smallamount f misalignmentan drasticallyncreasehe ocalshearstress ta ointand nduce ending tress.

3.6.6 ANGULARMISALIGNMENT

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright 2006,TWI LtdTWIW[' WORLD CENTREFORMATERIALS JOININGTECHNOLOGY

-50mm

ANGULARMISALIGNMENT

3.22


56/357

DescriptionMisalignment etween wo weldedpiecesparallel r at the ntended ngle.Causesand preventionSame s or inearmisalignment.

such that their surfaceplanesare not

3.6.7 INCOMPLETELY ILLED GROOVE

DescriptionA continuosor intermittent hanneldepositionfweld illermetal. in thesurfaceof a weld due to insufficient

Causes PreventionInsufficient eldmetal lncreasehenumber fweld unslrreqular eldbead urface Retrainwelder

CommentsThis mperfectioniffersromundercut, s incompletelyilledgroove educeshe oadbearing apacity f a weld,whereas ndercut roduces sharp tress-raisingotchattheedgeof a weld.

WeldingnspectionRe v0 Ju n06WeldingmperfectionsCopyright 2006,TWI Ltd

TWIwflt WORLD CENTREFORMATERIALSJOININCTECHNOLOGY3.23


57/357

3.6.8 RREGULAR IDTH

DescriptionExcessiveariationnwidthof theweld.

GommentsAlthoughhis mperfection aynot affect he ntegrity f completed eld, t can affecttne wiJtnof HAZand reduce he loadcarrying apacity f the oint (in case of fine-grained tructural teels)or impaircorrosionesistancein caseof duplexstainlesssteels).3.6.9ROOTCONCAVITY

DescriptionA shallow roove hatoccurs ue o shrinkage t the rootof a buttweld.

Causes PreventionSevere rcblow Switch romDC o AC,keepan as shortaspossible rc engthlrreqular eldbeadsurface Retrainwelder

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright@2006,TWI Ltd


3.24 TWIwct


58/357

Causes PreventionInsufficientrcpower o Produceoositive ead RaisearcenergyExcessive ackinq as pressureTlG) Reduce as pressureLackof welder kill RetrainwelderSlaqfloodinq n backingbar groove Tiltwork o prevent laq loodingGommentsTheuseof a backing trip anbe used o controlhe extent f the rootbead.3.6.10 BURN HROUGH

DescriptionA collapse f heweldpool esultingn a hole n heweld.Causes PreventionInsufficientravel peed Increasehe ravel peedExcessive eldinq urrent Reduceweldinq urrentLack of welderskill RetrainwelderErcessive rinding f root ace Morecare aken, etrainwelderExcessiveootqap Ensure orrectit up

GommentsThis s a gross mperfection,be repairedby bridgingheattention.whichoccurs asicallyuegap formed nto the joint, to lackof welderskillbut requires great . lt candealof

WeldingnspectionRev0 Jun06WeldingmperfectionsCopyright@2006, WILtd

3.25 TWI WoRLDcENTREFoRwct ffif"t:'"1"^'""


59/357

3.7 MISCELLANEOUSMPERFECTIONS3.7.1 STRAYARC/ARCSTRTKE

DescriptionLocaldamageo the surface f the parentmetaladjacento the weld, esultingromarcingor strikinghe arc outside he weldgroove.The result s in formof rindomareasof fusedmetalwhere he electrode,he holder,or current eturnclamphaveaccidentallyouchedhe work.

Causes PreventionPooraccess o the work lmprove ccess modify ssemblysequence)Missingnsulationn electrode olderor torch lnstitute regularnspectionchemeorelectrode olders nd orchesFailureo provide n nsulatedestingplace or heelectrode older r torchwhennot n use

Provide n nsulatedesting laceLoose urrenteturn lamp Regularly aintain urrent eturn lampsAdjusting ire ed MAGwelding)wthqut solating elding urrent Retrain elder

GommentsAn arc strikecan producea hard heat-affectedone, which may containcracks.Thesecan ead o serious rackingn service.t is better o removean arc strikebygrindinghanweld epair.

Welding nspectionRe v0 Ju n06WeldingmperfectionsCopyright@2006,TWtLtdTWIwct WORLD CENTREFORMATERIALS JOININGTECHNOLOGY3.26


60/357

3.7.2 SPATTER

DescriptionGlobules f weld metalor fil lermetalexpelled uringsurface f parentmetalor solidified eld netal. welding and adhering o the

Causes PreventionHioh rccurrent Reduce rc currentMaoneticrcblow Reduce rc enqth r switch oAC powerIncorrectettingsor GMAWprocess Modify lectrical ettingsbutbe carefulto maintainull usion!)Damo lectrodes UsedrvelectrodesWrong electionf shieldingas(100% o') Increase rgon ontentf possible,howeveroo higha ohof Argonmay eadto ackof penetration

CommentsSpattern tself s a cosmeticmperfectionnddoesnot affect he ntegrity f theweld.However s it is usually ausedby an excessive elding urrent,t is a sign hat hewelding onditions re not dealand so thereare usuallyotherassociated roblemswithin he structure.e. highheat nput.Note hatsomespatters alwaysproduced yopen arc consumable lectrodeweldingprocesses. nti-spatter ompounds an beusedon heparentmetal o reduce ticking nd he spatter an henbe scraped ff.

3.27eldingnspectionRe v0 Jun06WeldingmperfectionsCopyright 2006,TWI Ltd

TWI woRLDcENTREFoRvcc,ffi;*^^n


61/357


62/357

Temper olour visible xide ilm) rootoxidationDescriptionLightly xidised urfacen heweldzone.Usually ccursn caseof stainless teels

3.8 ACCEPTANCESTANDARDSWeld imperfectionsan seriously educe he integrity f a weldedstructure.Therefore, rior o service f a weldedoint, t is necessaryo locate hemusingNDEtechniques,ssessheirsignificance,nd akeaction o avoid heir eoccurrence.The acceptance f a certainsize and typeof defect or a givenstructuresnormally xpressed s thedefectacceptancetandard. his s usuallyncorporatednapplicationtandardsr specifications.All'normalweld mperfection cceptancetandardsotally ejectcracks.However,nexceptionalircumstances,ndsubjecto theagreement f all parties, racksmaybeallowed o remain f it can be demonstratedeyonddoubt ha t they will not lead ofailure.This can be difficult o establishand usually nvolves racturemechanicsmeasurementsndcalculations.It is importanto note hat the levelsof acceptabilityary betweendifferentapplications, nd in most cases vary betweendifferent tandards or the sameapplication. onsequently,hen nspecting ifferentobs it is importanto use theapplicabletandard r specificationuotedn the contract.Once unacceptable eld imperfectionshave been found, hey have to beremoved.f theweld mperfections at thesurface,he irstconsiderationswhethertis of a type,which s normally hallow nough o be repaired y superficial ressing'Superfiiialmplieshat,after emoval f thedefect,he remaining aterialhicknessssufficient ot o requireheaddition f furtherweldmetal.lf the defect s too deep, t mustbe removed y somemeansand newweldmetal dded o ensurea minimum esignhroathickness.3.29eldingnspectionRe v0 Jun06WeldingmperfectionsCopyright 2006,TWILtd

TWI woRLDcENTREToRvf,ctffit#;';*'


63/357

Replacing emovedmetalor weld repair(as in fillingan excavation r re-makinga weld oint)has o be done n accordance ithan approved rocedure.herigorwithwhich hisprocedures qualifledwilldependon the applicationtandardorthe ob. In somecases t will be acceptableo use a procedure ualifiedor makingnew ointswhether illingan excavation r makinga completeoint. f the levelofreassuranceequireds higher,he qualification ill have o be madeusingan exactsimulation f a welded oint,which s excavated nd then refilledusinga specifiedmethod, n either case, qualificationnspectionand testingwill be required naccordance ith heapplicationtandard.

3.30elding nspectionRe v0 Jun06Welding mperfectionsCopyright@2006,TWI LtdT\MIWf,' WORLD CENTREFORMATERIALS JOTNINGTECHNOLOGY


64/357

TWI woRLD ENTREoRV6EE MATERIALS.}oININGtEB- TECHNOLOGYQuestions

Weld defects

QU1. Give wo maincausesor heoccurrence f a burn hrouqh ndprevention.

QU2. Give womaincausesor he occurrence f lackof rootpenetrationna single-V ut tweld.

QU3. Sketchhe ollowing efects, n a single-V ut tweld.a) Incompleteootpenetrationb) Lackof root usionc) Incompleteilled rooved) Concave oot

QUs. Give ivedefectshatmayoccurwhenwelding arbon teelusing heMMAwelding rocess ith he current etting o low.

QU6. Give hreepossible auses or ackof sidewall usion n singleV buttjointwithMMA process nd which type of NDT rnethods the mostsuitableo detect ts occurrence?

Welding inspectionRev 0 Jun06Copyright@2006,TWI Ltd Q U 3


65/357

Section04DestructiveTesting

WeldingnspectionRev0 Jun06CopyrightO 2006,TWI LtdT\I/f woRLD cENTRE oRlmnt MATERIALSJOININGvlJ/-./t TECHNOLOCY


66/357

4.0 DESTRUCTIVEESTING4.1 INTRODUCTION

EuropeanWeldingStandardsequire est coupons hatare made or weldingprocedure ualificationesting o be subjectedo non-destructiveestingand thendestructiveesting.The testsare calleddestructiveestsbecause he weldedoint s 'destroyed'whenvariousypesof testpieceare aken rom t.

Destructiveestscan be dividednto2 groups, amely:tr thoseused o measure mechanicalroperty - quantitativeestsD thoseused o assess he ointquality - quatitativeests

Mechanical ests are quantitative ecause a quantity s measured amechanicalroperty uchas tensile trength, ardness nd mpactoughness.

Qualitativeests are used o verify hat the oint is free fromdefects they areof soundquality and examples f theseare bend ests,macroscopicxaminationand ractureests fillet racture& nick-break).4.2 TESTTYPES,TESTPIECES TESTOBJECTIVES

The various ypes of mechanicalest are used by materialmanufacturers/supplierso verify hat plates,pipes, orgings tc have he minimum roperty aluesspecifiedorparticular rades.Design ngineers se he minimum roperty alues isted or particular radesof material s the basis or designand he mostcosteffective esigns re basedonan assumptionhat weldedointshavepropertieshat are no worse han hoseof thebasemetal.Thequantitativemechanical)ests hat are carried ut for weldingprocedurequalification re intended o demonstratehat the joint properties atisfy designrequirements.The emphasis n the following ub-sectionss the destructiveests and testmethodshatarewidelyused or weldedoints.

WeldingInspection 4.1 TWI woRLDcENTREFoRs3Ll,lilJ?"o,"n wi ffi"f#;*'Copyright@2006,TWI Ltd


67/357

4.2.1 TRANSVERSEENSILE ESTS. Test ObjectiveWelding rocedure ualificationestsalways equireransverseensile ests oshow hat hestrength f the ointsatisfieshe design riterion.. TestSpecimensA transverseensile es t piece typicalof the type specifiedby EuropeanWeldingStandardss shown elow.

parallellength

Standards,uchas EN 895, hatspecify imensionsor transverseensilees tpieces equire ll excessweldmetal o be removed nd he surface o be free romscratches.Testpiecesmay be machinedo representhe ull hickness f the ointbut orvery hick oints t maybe necessaryo takeseveralransverseensile es tspecimensto beable o test he ul l hickness.

. Test MethodTest specimens reaccuratelymeasured efore esting.Specimens re thenfitted into the jaws of a tensile esting machineand subjectedo a continuallyincreasingensileorceuntilthe pecimenractures.The tensile trengths calculated y dividinghe maximumoad by the cross-sectional reaof the estspecimen measured efore esting.The test s intendedo measure he tensilestrenqth f the iointand therebyshow hat he basis or design,he basemetalproperties,emainshe validcriterion.

. AcceptanceCriterialf the test piece breaks n the weld metal, t is acceptable rovided hecalculated trengths not ess han he minimum ensile trength pecified, hich susuallyhe minimum pecifiedor hebasemetalmaterial rade'

WeldingnspectionRev0 Jun06DestructiveestingCopyright@2006,TWILtd

4.2 T\MIw[t WORLD CENTREFORMATERIALS OININGTECHNOLOGY

Weldmetal


68/357

lf the test specimen reaksoutside he weld or fusionzone, the weld ointstrengthmay be acceptable rovided hat it is not less than 95% of the minimumtensile trength pecifiedor hebasemetal.

4.2.2 ALL-WELD ENSILE ESTS. Test ObjectiveThere may be occasionswhen it is necessaryo measure he weld metalstrength as part of welding procedurequalification particularly or elevatedtemperatureesigns.

The test is carriedout in order o measure ot only ensilestrength ut alsoyield orproofstrength) nd ensi le uctility.All-weld ensi le ests are also regularly arry out by welding consumablemanufacturerso verify hat electrodes nd flllerwiressatisfy he tensileproperties

specified y he standardo which heconsumablesrecertifled.. TestSpecimensAs the name ndicates,est specimens re machinedrom weldsparallelwiththeir ongitudinalxisand hespecimenaugeengthmustbe 100Yo eldmetal.

lirnimurngaralielengrrReund cross sectional

Round tensilespecimen rom awelding procedurequalification fesfpieceRoundtensr'lespecimen from anelectrode classification fest piece

Crosg-secllonal r'Ei A

WeldingnspectionRev0 Jun 06DestructiveestingCopyright@2006,TWI Ltd

WORLD CENTRE FORMATERIALS JOININGTECHNOLOGY

4.3 TWIw[t


69/357

. TestMethodSpecimensresubjectedo a continuallyncreasingorce n thesameway hattransverseensile pecimens re ested.Yieldand proof stressare measured y means of an extensometerhat isattachedo the parallelengthof thespecimen nd s able o accurately easureheextension f thegauge engthas he oad s ncreased'Typical oad extension urvesand their principalcharacteristicsre shownbelow.

Uhimrte:trenqlhHartirlinrir ,/ / lrarturt

'nelki lq'rxtnnnt tlri-r *int

5oftdvrtile leel5rrralediekl x:ittt

P.oot sl{Bnolh I

H St=inS*esl!rgc Fre::ngr',Eii de!,3:matlnn

I

tc

Load-extensioncurue for a steelthat showsa distinctyield pointatthe elastic imit

Tensile uctilitys measuredn twoways,namely:% elongationf thegauge ength% reduction f areaat the pointof fracture

Load-extensioncurve for a steel(orother metal) that does not show adistinct yield point; proof stress s ameasure of the elastic imit

5Iriirr, 1+:rqalir::trer rril et:r,1tlt

WeldingnspectionRe v0 Jun06DestructiveestingCopyright@2006,TWI Ltd

4.4 TWI y?::.::)=.:'lwcr ffif#;'.:^^"


70/357

Schematicsa)and(b)below llustratehese woductilitymeasurements'

Sriginalgauge argtl

Garige lenglhal faal|'lre

Origitraldianteler d

:I,.--

{a}

4.2.3

Redttction in Giamedlarrieler/ h :t v i

IMPACT OUGHNESSESTS. TestObjectiveCharpyv-notchtestpieceshavebecometheinternat ional |yacceptedmethodfor assessingesisianceo'britile ractureby measuringhe energy o initiate, ndpropagate, .ru.t tiom a sharpnotch n a siandard izedspecimen ubjectedo animpactoad.

Designengineers eed o ensure hat he toughness f the steel hat s usedfor a particulartem will be highenough o avoid Oiittteracture n serviceand soimpact specimensare tested at a-iemperature hat is related o the design

temperatureor he abricatedomponent'c-Mn and ow alloysteelsundergo sharpchange n their esistanceo brittlefractureas theirtemperatures lowerJo o that a ste-ethat may havevery goodtoughnessat ambient temperatur"-"y show extreme brittleness t sub-zerotem-peraturesas llustratedn ollowingigure'

WeldingnsPectionRe v0 Jun06DestructiveestingCopyrightO 2006,TWI Ltd

TWIwcrWORLD CENTREFORMATERIALS JOININGTECHNOLOGY

Giarneter at fatltlre

4.5


71/357

upf lsr hel fenergy :g-otct)Lotr1rl+,oGCL-E

Transition emperature(-200c)

ducl[era*ture{S%eryst6EtEnrty}

lowershelfenergybrittle racture(100% rystallinity)

-50 -40 -30 -20 -10 30 40Test Temperature'C)

The transition emperatures defined as the temperaturehat is mid-waybetweenhe uppershelf maximumoughness) nd ower helf completely rittle).ntheabove chematiche ransitionemperatures-20"C.. Test SpecimensThe dimensionsor estspecimens avebeenstandardisednternationallyndare shownbelow or full s ized specimens.Thereare alsostandard imensionsorsmaller ized pecimens,orexample Omm 7.5mm& 1Omm 5mm.

10 20

WeldingnspectionRev0 Jun06Destructive estingCopyright@2006,TWI Ltd

4.6 TWIw[t WORLD CENTRE FORMATERIALS JOININGTECHh-OLOGY


72/357

charpy v-notch estpiecedimensionsor full sizedspect'mens

Specimens re machined rom welded test plateswith the notch positionlocatedn differentocations ccordingo the testing equirementsut ypicallyn thecentre f theweldmetalandat positions cross he HAZ as shownbelow.

Fu*-*ia,rtFusi*n irte+

l ine '2rnrn Fusisft ineSmrn iJU+ld etal

>40mm

->+:l

t\r",bldtetal ,Eusinnine f= rnmFuisicrtitte+ 2ram Fusianisre

Typical notchpositions for Charpy V-notch test specimens from double'Vee buttwelds. Test Method

Test specimensare cooled o the specified est temperature y immersion n aninsulated ath containing liquid hat is held at the test emperature'

Welding nspectionRev 0 Ju n 06DestructiveTestingCopyright@ 2006, TWI Ltd

4.7 TWIwctWORLD CENTREFORMATERIALSJOININGTECHNOLOGY


73/357

After allowing he specimen emperatureo stabilise or a few minutes t isquickly ransferredo the anvil'of the testmachine nd a pendulum ammer uicklyreleased o that hespecimen xperiencesn mpactoadbehind he notch.The main eatures f an mpact estmachine reshownbelow.

lmpact specimenon the anvil showingthehammer positionat point of impactlmpact testing machine

Charpy V-notch fesf pieces- before and after testing

Scale

4.8eldingnspectionRev0 Jun 06Destructive estingCopyright@2006,TWILtdTWIwct WORLD CENTREFORMATERIALS JOININGTECFINOLOGY


74/357

The energy absorbed'by the hammerwhen t strikeseach est specimensshownby the p6iitionof the himmer 'pointer'on the scaleof the machine'Energyvaluesaregiven nJoules'lmpact est specimens re taken in triplicate 3 specimensor each notchposition)'b"."ur" there swillalways end o be somevariationn recorded nergyornominaliyhesame est particularlyorweldments'

r AccePtance riteriaEach est result s recorded nd an average aluecalculatedor eachset ofthree ests.Thesevaluesare comparedwith he valuesspecified y the Applicationstandard rclient o establish hether pecifiedequirementsavebeenmet'After impact esting,examination f the test specimens rovidesadditionalinformationbout heir orijhness haracteristicsnd maybe added o the est eport'namely:

which ndicates rittle racture;1OO%ndicates ompletely rittle racture

behindhe notch as indicated elow; he arger he value he ougherhespecimen

L-ateraIeontradion

nsfilEteralxpanslonbrittleracturs

a + b = lat+ralexFansls{lduc-'tileraeture

A specimenhatexhibits xtreme rittleness ill showa cleanbreakwithandbothharves f the specimen avinga compreteryrat racture aceswith ittleor nolateral xpansion.

Welding nsPectionRev0 Jun06DestructiveestingCopyright@2006,TWILtd

WORLD CENTREFORMATER1ALSJOININGTECHNOLOGY

4.9 TWIWIT


75/357

A specimenhatexhibits erygood oughness ill showonlya smalldegreeofcrackextension, ithout racture nda highvalueof lateral xpansion'4.2.4 HARDNESS ESTING. TestObjectiveThe hardness f a metal s its' resistanceo plasticdeformation nd this isdeterminedy measuringhe resistanceo indentationy a particularypeof indenter.

A steelweldmentwithhardness bovea certainmaximummaybe susceptibleto cracking, itherduring abricationr in service, nd welding rocedure ualificationtestingor certain teelsandcertain pplicationsequireshe estweld o be hardnesssurveyedo ensure hat are no regions f the weldment hat exceed he maximumspecifiedardness.Specimens reparedor macroscopicxaminationan alsobe used or takinghardnessmeasurements t variouspositions f the weldment referred o as ahardness urvey.

" TestMethodsThereare3 widelyusedmethodsor hardnessesting, amely:. TheVickers ardnessest - usesa square-baseiamond yramidindenter. TheRockwell ardnessest usesa diamond one ndenter r steelball. The Brinell ardnessest - usesa ball ndenter

Thesizeof an indentations the measure sed o givea hardness alue thesmallerhe ndentationheharder hemetal.

WeldingnspectionRev0 Jun06DestructiveestingCopyright@2006,TWI LtdTWIwctWORLD CENTREFORMATERIALS JOININGTECHNOLOCY4 . 1 0


76/357

TheVickersmethod f testings llustrated y theschematichownbelow'fulcrum

square asedpyramidalndentet

(a) Mckersndentation (b) measurement f mpressiondragonals

BothVickersandBrinellmethods resuitableor carrying uthardness urveyson specimens reparedor macroscopicxaminationfweldments'A typical ardness urvey equireshe ndentero measurehe hardnessn the

basemetii (on bothsidesof theweld), n theweldmetalandacrosshe HAZ(onbothsides f heweld).TheBrinellmethodgivesan ndentationhat s too arge o accuratelymeasurethehardnessn specific e-gionsf the HAZand s mainlyused o measure ardnessof basemetals.

WeldingnspectionRev0 Jun06DestructiveestingCopyright 2006,TWI Ltd

TWIwctWORLD CENTRE ORMATERIALS JONINGTECHNOLOGY

pyramid

4 . 1 1


77/357

A typical ardness urvey usingVickers ardnessndenter)sshownbelow:

Hardness aluesare shownon test reportsas a number ollowedby lettersindicatinghe estmethod,orexample:240 HV10 = hardness 40,Vickersmethod, 0 Kg ndenteroad22 HRC = hardness 2, Rockwellmethod, iamond one ndenterscaleC)238 HBW = 238hardness, rinellmethod,ungsten all ndenter

4.2.5 CRACKTtPOPENTNGTSPLACEMENTCTOD) ESTTNGr TestObjectiveCharpyV-notch estingenables ngineerso make udgements bout isksofbrittle ractureoccurringn steelsbut a CTOD est measures materialpropertvfracture oughness.

Fracture oughness ata enablesengineerso carry out fracturemechanicsanalysesuchas:

. calculatinghe size of a crack hatwould nitiate brittle racture ndercertainstress onditionst a particularemperature

. the stress hatwouldcausea certain ized rack o givea brittleractureat a particularemperatureThis data is essentialor makingan appropriate ecisionwhen a crack sdiscovereduring nspection f equipmenthat s n-service.

. Test SpecimensA CTOD specimens prepared s a rectangularor square)shapedbar cuttransverseo the axisof the buttweld.A V-notchs machined t thecentreof thebar,whichwillbe coincident ith he estposition weldmetal r HAZ.

WeldingnspectionRev0 Jun06Destructive estingCopyright@2006,TWI Ltd

4 . 1 2 TWIwct WORLD CENTREFORMATERIALS ]OININGTECHNOLOGY


78/357

A shallow awcut s thenput nto he bottom f the notchand he specimensthenput ntoa machinehat nduces cycric endingoaduntir shailowatigue rackinitiatesrom he sawcut.The specimens re relativelyarge typically avinga cross.section x 28and ength 108 1A= tuil hickness f t-heweiol.Thetestpiecedetailsare shown ntheschematic elow.

o TestMethodcToD specimens re usually estedat a temperatureelowambient nd hetemperatur" i the specimens controlled y immersionn a bath of liquid hathasbeencooled o the requiredest emperature'A load is applied o the specimen o bend cause bendingand induceaconcentratedtressat the ip of the crackanda clipgauge,attachedo the specimenacross he mouthof the machined otch,givesa reiOingof the increasen widthofthemouthof thecrackas he oad s graduallyncreased.For each test condition' position f notchand test temperature)t is usualpractice o carrYout hree ests'

*1,l-ffii L lSectionhrougnotchMachined otch

WeldingnsPectionRev0 Ju n06DestructiveestingCopyright 2006,TWI Ltd


4 .1 3 TWIwct


79/357

Theschematics elow llustratehemain eatures f the CTOD est.

Tip opening

Fracture oughnesss expressed s the distance hat the crack tip openswithoutnitiation f a brittle rack.The clipgaugeenables chart o be generated howinghe increasen widthof the crackmouthagainst ppliedoad romwhicha CTODvalue s calculated.

. AcceptanceCriteriaAn applicationtandard r Clientmay specify minimumCTODvalue hatindicates uctileearing. lternatively,he testmaybe for information'o thata valuecanbe used or anengineeringritical ssessment.A very oughsteelweldment illallow he mouthof thecrack o openwidelybyductile earingat the tip of the crack whereasa very brittleweldmentwill tend tofracturewhen he appliedoad s quite ow and without ny extension t the ip of thecrack.CTOD valuesare0.1mm britt le ehaviour:expressedn millimetres typicalvalues might be -1mm= very ough ehaviour.WeldingnspectionRe v0 Jun 06Destructive estingCopyright@2006,TWILtd

T\/f|I woRLDCENTREFoRwct ffi#*^*


80/357

4.2.6 BENDTESTING. Test ObjectiveBend estsare routinelyaken romweldingprocedure ualificationestpiecesandsometimes ave o be aken romwelder ualificationestpieces.

Subjectingpecimenso bendings a simplemethodof verifyinghat hereareno regionsn a buttweld hathave owductility.Ductilitys notactuallymeasured ut t is demonstratedo be satisfactoryf testspecimens in withstandbeingbent without ractureor fissuresabovea certainlength.

. TestSpecimensThereare4 typesof bendspecimen,amely:FacebendSpecimenakenwithaxis ransverseo buttweldsup to -12mm hickness ndbentso hat he aceof theweld s on he outside f thebend face n tension)RootbendTestspecimenakenwithaxis ransverseo buttweldsup to -12mm h.icknessand bentso that the rootof the weld s on the outsideof the bend(root intension)SidebendTestspecimenakenbuttwelds> -12mmtension)Longitudinal end

as a transverselice -1Omm) rom he full hickness fand bentso that the full oint thicknessested side in

Testspecimenakenwith axisparallel o thespecimenhicknesss - 12mmand he facetensionlongitudinalxisof a buttweld;or rootof weldmaYbe tested n

WeldingnsPectionRev0 Jun06DestructiveestingCopyright 2006,TWI Ltd

4 .1 5 'ffX/T woRLDcENTREFoR;--;- MATF-RIALS JOININGt l // /z ,^_ ^-_WJIJ' I'ECHNULUUY


81/357

Former

Ltt--

Ltt--

ItT-

. TestMethodBend esis for weldingprocedure ualificationand welderqualification)reusually uided end ests'Guidedmeans hat he strainmposed n the specimens uniformly ontrolledby beingbentaround formerwitha certainadius'The radiusof the formerused or a particulares t s determinedy the typeofmaterialhat s being estedand heductilityhatcan be expectedrom hatmaterialn

theunweldedondition.The radiusof the former s usually xpressed s a multiple f the specimenthickness nd for C-Mnsteel t is typically t (t is the specimenhickness) ut formaterialshathave ower ensile uciiiityhe radiusof the ormermaybe greaterhan10t.The standard hat specifieshe test methodwill specify he minimumbendangle hat hespecimenmustexperiencend his s typically 20'.

. AcceptanceCriteriaBend estspieces hould xhibit atisfactoryuctility y notshowing racksoranysignsof significantissures r cavities n heoutside f thebend'Small indications'less than about3mm in lengthmay be allowedby somestandards.

WeldingnsPectionRe v0 Ju n06DestructiveestingCopyright@2006,TWI Ltd

4 . 1 6 TWI WORLD CENTREFORMATERIALSJOININGTECHNOLOGYlf,r


82/357


83/357

. AcceptanceCriteriaThe standardor welderqualification,r application tandard, ill specify heacceptance riteria or imperfectionsuchas lack of penetrationnto the root of thefrril.O solid nclusions ndporosityhatarevisible n he racture urfaces.Test reports houldalso give a description f the appearance f the fractureandlocation f anY mPerfection4.2.7.2 BUTTWELDFRACTURES'NICK-BREAK'ESTS)o TestObjectiveTheobjective f these ractureests s thesameas for illet ractureests.

These estsarespecifiedorwelder ualificationestingo European tandardsas an alternativeo radiography,r are additionalo radiographyor certainweldingpio.".r"r, but t is not uled for welding rocedure ualificationesting o EuropeanStandards.. TestSpecimens

Testspecimens re taken rom a buit weld and notched o that the fracturepathwillbe n thecentral egion f theweld.Typicales tpiece ypesareshownbelow'

. TestMethodTestpieces remade o fracture y hammering r hree-pointending'o AcceptanceCriteriaThe standard or welderqualification,racceptance riteria or lmperfectionsuch asporosityhatarevisible n the racture urfaces.

applicationtandard, ill specify helack of fusion, olid nclusions nd

Testreports houldalsogivea description f the appearance f the fractureand ocation f anY mPerfection.WeldingnspectionRev0 Jun06DestrucliveestingCopyright@2006,TWI Ltd

TWIWC' WORLD CENTRE FORMATERIALS JOININGTECHNOLOGY4 . 1 8


84/357

4.3 MACROSCOPICEXAMINATIONTransverse ectionsrom butt and filletweldsare requiredby the.Europeanstandards or weldingprocedure ualificationestingand may be requiredor some*"rJ"r qualificatione-stingor assessinghequality f thewelds'This sconsideredn detail n a separate ection f theseCourseNotes'

4.4EURoPEANSTANDARDSFoRDESTRUCT|VETESTMETHoDSThe following tandards re specified y the EuropeanWeldilg Standardsordestructiveesting t;;lding procedure ualifitationestweldsand or somewelderqualifi ation estwelds.

EN 875 Destructiveestson welds n metallicmaterials lmpact ests Testspecimenlocat ion,notchorientat ionandexaminationENgg5 Destructiveestson welds n metallicmaterials TransverseensiletestEN 910 Destructiveestson welds n metallicmaterials Bend estsEN 1321 Destructiveests on welds n metallicmaterials Macroscopic ndmicroscoPicxaminationfweldsBS EN 10002 Metallicmaterials Tensile esting.Part1: Methodof testat ambienttemPeratureBS EN 10002 Tensileesting f metallicmaterials. ar t5: Method f testat elevatedtemPeratures

Welding nsPectionRev0 Jun06DestructiveestingCopyright@2006,TWILtd

4 .1 9 '|-IXII WoRLDcENTREFoRlTiia MATERIALS oININGVIJLI, TEcHNoLoGY


85/357

TWI woRLDcENTRE oRABE'YBBE MATERIALS OININGI&EE TECHNOLOGY

QuestionsDestructive testing

QU1. Whatmechanicalproperties an be measured rom a tensile es tfor the approvalof weldingprocedure?

QU2. Whatare he objectiveof a charpy mpact est andwhat units heresultgives n?

QU3. Givea briefdescriptionof the foilowing ests and state tspurpose:a) Bend est.b) Nick-break est.c) Macro.d) Fracture illet test.

QU4. What s the main objectiveof hardness esting and why this testis very mportantwhen approvinga wetdingprocedure?

Welding nspectionRev 0 Jun06Copyright@2006,TWI Ltd Q U 4


86/357


87/357

Section05WPS& WelderQualifications

Welding nspectionRe v0 Ju n06Copyright 2006,TWI LtdTWI y9*_".:::y.:?:wcrm*'J;^'


88/357

5.0 WELDING ROCEDUREUALIFICATIONWELDERQUALIFICATIONGENERALWhenstructuresnd pressurisedtemsare abricated y welding,t is essentialthatal l he weldedointsaresoundandhavesuitable ropertiesor heirapplication.

Controlof weldings achieved y meansof WeldingProcedure pecifications(WpS's) hatgivedetailedwrittennstructionsbout he welding onditionshat mustbe used o ensurehatweldedointshave he required roperties.AlthoughWPS's are 'shop floor' documentso instructwelders, hey aredocumentshl t weldingnspectors lsoneed o be familiarwith.This s becauseheywill need to refer o WPS'swhen they are checking hat weldersare working naccordance ith he specifiedequirements.Weldersneed o be able o understand PS'sand to have he skill o makewelds that are not defective nd have o demonstratehese abilities eforebeingallowedo makeProductionelds.

5.1 QUALIFIEDWELDTNGROCEDURESPECIFICATIONSIt s industry racticeo usequalifiedWPS's or mostapplications'A welding rocedures usuallv ualified y makinga testweld

cswip 3.1_welding inspection-wis5-2006.pdf

Documents