WELDING-INSPECTION-AND-Q教學(xué)講解課件

WELDINGINSPECTIONANDQUALITYCONTROLUponcompletionofthismoduleyouwillbeableto:Identifythedifferentinspectionmethodsusedinnondestructivetesting.Theusesandthelimitationsofthedifferentinspectionmethods.CommonmethodsusedinNDEVisualInspection(VT)MagneticParticleInspection(MT)Liquid(Dye)PenetrantInspection(PT)X-Rayinspection(RT)Ultrasonictesting(UT)Airorwaterpressuretesting(LT)VISUALINSPECTION–VISUALTEST(VT)WhatisVisualInspection?NDTprocess–nondestructivetestingistheoriginaltermusedtoidentifyamethodofinspectionthatdoesnotdestroyaproductusefulness.Currenttermsincludenondestructiveinspection(NDI)ornondestructiveevaluationorexamination(NDE)Examinationwiththeeye–thereforeyouareonlyabletoDETECTSURFACEDISCONTINUITIES.MostimportantandmostextensivelyusedNDE/NDI/NDTmethod(beforeanyNDTorDTbeapplied.)II.AdvantagesA.Usuallyinexpensive-themajorityofexpensewillbeintheinspector’swage.B.Equipmentissmallandinexpensive–there’salotofequipmenttoaidinvisualinspection,butallsmallandinexpensive.C.Nopoweredrequired–thismakesVTthemostportableNDTprocess.D.Canavoiddefectsandcostlyrepairs–byabletomakeintermittentinspectionII.DISADVANTAGESRequirestrainingandexperience–theinspectorshouldbefamiliarwithalltheweldingprocess.Musthaveagoodeyes–theAWSrequires20-40naturalorcorrecteddistanceacuityforacertifiedweldinginspector.Maynotdetectinternaldefects–limitedtosurfacediscontinuitiesonly,butitmightgiveindicationofsubstanceindication.ThencanbesupplementedbysomeotherNDTmethod.Nopermanentrecords–theinspectormustmaintainawrittenlog,supplementedbypictures,andtaperecordedreport.Subjecttohumanerror–mustspendadequatetimetopreventerrors.IV.FivestepsofVisualInspection.Inspectionpractice–establishadefiniteproceduretoinsureadequateandconsistentcoverage.InspectionpriortoweldingInspectionduringweldingInspectionafterweldingMarkingandmakingrepairsV.Equipmentrequired.Flashlight–usedtoremoveshadowswhenanextensionlampcan’tbeused.Magnifyingglass–lowpowercanbeusedwithcaution,ifallowedbycustomerorcode.Protectivelenses–pocketviewerwithpropershadelenstowatchtheweldingtakingplace.Weldgage–arehandheldmeasuringdevicesusedtoassistduringweldingandforfinalinspection.E.Hammerandchisel–toremovespatterorslagfromweldpriortoinspection.F.TemperatureIndicatingDevices–somemethodmustbeusedtodeterminethepreheating,interpassandpostheatingtemperatures.Pyrometerandtempelstickorcrayonsarecommonlyused.G.Magnet–amagnetcanbeusedtohelpdetermineamaterilatype.VI.InspectionBeforeWeldingDrawing–drawingarecompleteandaccurate?Positionofwelds–doesthepositioncalledforcorrespondtotheprocedureorspecification?Inverticalisdirectionoftravelcorrect?Weldingsymbols–iftheyareusedaretheycompleteandaccurate?Weldingprocedure–istheprocedurecompleteandaccurateaccordingtothecodeorspecification?E.MaterialDidpurchasingobtainthecorrectmaterialsuchasbasemetaltypeandsize.Thecorrectelectrodetypesizeandthecorrectshieldinggastypeandgrade.Materialsshouldbecheckedfordefects.Basemetalshouldbecheckedrust,mill,scale,laminationsordelaminations.3.Isthematerialpreparationcorrectandaccordingtoprocedure,suchasanglesandconditionafterpreparation.F.AssemblyInspectforproperfitup,asthiswillpreventdiscontinuitiesfromoccuring.Jigsandfixtureswillassureproperalignment.Makesuretheyarecleanandfreespatterandnotdamaged.Thetackweldsareonlyshortwelds,butthequalitymustbethesameasallotherwelds.Thetackweldsmustbemadewiththesameelectrodesthatareusedfortherestofthewelds.Preheatwillbeusedtoslowthecoolingrateandpreventdistortion.Thepreheatcouldbeusedpriortotackingand/orpriortowelding.G.EquipmentInspecttheequipmentforanydamagedsuchasdamagedcables,damagedgroundclamps,orelectrodeholders.Inspectthearcvoltageandamperagemetersmakingsuretheyarewithinrange.VII.InspectionDURINGwelding.Electrodes–inspectforusageofproperelectrodes,types,sizeandstorage.Lowhydrogentypemustbestoredinastabilizingoven.Rootpass–thefirstlayerorrootpassisthemostimportantandisparticularlysusceptibletocracking.Thickermaterialwillcrackandwillrequiremorepreheat.Subsequentpasses–inspectionofsuccessivelayersissometimescarriedoutwiththeassistanceofworkmanshipStandard.Checkforcontourorundercutasthesearegoodplacesforslagtobetrapped.Checkforpropercleaningbetweenpassesasthiscanpreventslagentrapment.D.Craterformation–makesurecraterarefilledasthisareareaswherecrackareeasilyformed.E.Weldsizeandsequence–aretheweldsizeaccordingtotheprintandisthelayerandsequenceaccordingtotheprocedure?Theuseofvariousgageswilldeterminethis.VIII.InspectionAfterweldingTheapplicablecodeorstandard–itwilllistacceptancestandardsTheywillgenerallycoverthefollowingareas;Weldsize–usegagestocheckconformancetoprintsContourandfinish–isthecontourconvexorconcave,andwhatwascalledforinprint?Isfinishsmoothandfreefromsurfaceirregularities.Cracks–thecodeorstandardwillstateifanyisacceptableandwhatsize.

4.Overlap–itisanindicationoflackoffusion5.Undercut–ifallowedhowmuch?6.Spatter–whatisexcessive?IX.MakingrepairsA.Whenmarkingareastoberepairedthemarkingshouldbepositiveandclear.Itshouldbeamethodthatisunderstoodbyallinvolved,shouldbepermanentenoughtobeevidentaftertherepairhasbeenmadeandinspected,andthemarkingmustnotdamagedthepart.VisualInspection(VT)VisualisthemostcommoninspectionmethodVTrevealsspatter,excessivebuildup,incompleteslagremoval,cracks,heatdistortion,undercutting,&poorpenetrationTypicaltoolsforVTconsistofFilletgaugesMagnifyingglasses,Flashlights,&Tapemeasuresorcalipers.VT–VisualTestBeforewelding -RootFace -RootGap -BevelAngle -JointandFitupVISUALWhileweldingTheratetheelectrodemeltsThewaytheweldmetalflowsSoundofthearcThelightgivenofAfterweldingUndercutLackofrootfusionAnypinholesfromgasorslagAmountofspatterDimensionsofweldVT–VisualTestVisualInspection(VT)FilletgaugesmeasureThe“Legs”oftheweldConvexity(weldroundedoutward)Concavity(weldroundedinward)FlatnessLiquid(Dye)PenetrantInspection(PT)Liquidpenetrantinspectionusescoloredorfluorescentdyetocheckforsurfaceflaws.PTwillnotshowsub-surfaceflaws.PTcanbeusedonbothmetallicandnonmetallicsurfacessuchasceramic,glass,plastic,andmetal.PTdosenotrequiretheparttobeMagnetized.

DYEPENETRANTSTheseareanaidtovisualinspection 1.CleanerSolvent 2.Penetrant 3.DeveloperWillonlyfindsurfacedefectsUsecorrecttypeProcessPrinciple–6stepsSurfacepreparationPenetrantapplicationExcesspenetrantremovalDeveloperapplicationInspection/evaluationPostcleaningDYEPENETRANTSTypesRedFlouresantCAUTIONOilbasedWaterwashableDYEPENETRANTSDETECTIONII.Application:FerrousandnonferrousmaterialsPlasticandglass–ceramics-insulators-anythingthatisnonporousIII.Advantages:LowcostEaseinapplicationandinterpretation–easytoapplyandinterpretresult,discontinuitiesreadilyvisibleandportable.Lesstrainingtimeforapplicator–easyprocesstolearn.IV.Limitations:DetectsdiscontinuitiesthatisopentosurfaceonlyCannotbeusedonporousorabsorbentmaterialsV.Safetya.Ventilation–checkfortoxicfumesfromtestingmaterials.Checkforvolatility-explosiveorfireflashpointsb.Firesafety–thetestmaterialmaybenonflammablebutthepropellantusedwithspraycansmaybeextremelyflammable.VI.Types:Fluorescent(typeA)–adyethatemitsvisiblelightrayswhenviewedunderblacklight. 1.consideredtobemoresensitivethanthevisibletype 2.mustbeviewedunderultraviolet(blacklight)indarkenedoveralllightingconditions.Moreexpensivebecauseofequipmentrequired.Limitedfielduse.B.Visible(typeB)–abrilliantlycoloreddyethatishighlyvisibleundernormallightingconditions 1.Usenormallightingforinspection 2.consideredtobelessexpensive. 3.Simplesttouse. 4.Easytouseforfieldwork 5.noelectricpowerrequiredDualsensitivity–worksbothfluorescentandvisible.VII.ApplicationFollowApprovedProcedureCleananddrythesurface. -Solventcleaner2.Applypenetrant(brush,sprayordip)penetrantpowercomescapillaryaction3.Penetrationtime-minimumdwelltimeis5-20minutes3.Removeexcesspenetrant. -whenusingsolventtype,putsolventonaclothnotonthepart -excesspenetrantwillgivefalseindications4.Applydeveloperanallowdeveloperdwelltimeperstandardorspecification.A“ruleofthumb”developerdwelltimeisequaltoonehalfpenetrantdwelltime. -developerwilltendtomakediscontinuitiesappearlarger.6.Inspectandexamine–trueindicationsarecausedbypenetrantbleedingfromactualdiscontinuities.7.Cleanifrequired–sameasstep1.VII.LiquidPenetrantComparatorIdealtemperaturerangeofthematerialtobetestedis60?F–125?F.Ifthetestmustbedoneoutsideofthisrange,furtherqualificationmayberequired.Testblock–toestablishacceptabilitylimitsofcontaminationanddilutiontoseeifdeveloperandpenetrantareOK. 1.Platedpanels–brasspanelsareplatedwithnickelandchromiumarebenttoproducecracks. 2.steeltestblocks–annealedtype2010r302stainlesssteel.Sandblastedononesideonlywith100meshaveragesizegrit,gunheldat18”at60psitoachievevelvetyfinish.

3.aluminumtestblocks–type2024byheatingto975Fandquenchedtoformcracks.Usedtocheckcomparisonforoperatingoutofthenormaltemperaturerange.Usedalsotoqualifypenetrantifshelfisquestionable.Preparationforreuse–blocksshouldbecleanedwithsolventtoremoveallpenetrantfromcracksandthenheatedtodryandalsotodriveoutanyremainingsolvent.endMagneticParticleInspection(MT)MagneticParticleInspection(commonlyreferredtoasMagnafluxtesting)isonlyeffectiveatcheckingforflawslocatedatornearthesurface.MTusesametallicpowerorliquidalongwithstrongmagneticfieldprobestolocateflaws.(Particleswillalignalongvoids)MTcanonlybeusedonmaterialsthatcanbemagnetized.ItcannotbeusedbeusedfornonmagneticmaterialssuchasAusteniticStainlesssteelandaluminum.Principle:Anelectriccurrentisallowedtoflowinoranelectromagnetisappliedtopartofthespecimentocausemagneticfluxtoflowinthespecimen.Ifadefectexistinthesurfacelayer,itblocksthefluxflow,sothefluxflowisdirectedaroundthedefectwhileitpartiallyleakstotheair.Theleakingfluxformsapairofmagneticpoles,SandN,onbothsidesofthedefect.(asshown)SNSNSNSNSNSNSNSNSNSNSNSNNSFig.ASincethemagneticpoleshavelargerattractiveforcethanthesurroundingmaterialsurface,magneticparticlesareattractedbyandadheretothemagneticpoleswhileattractingeachother.Asaresult,amagneticparticlepatternwiderthanthedefectisformedonthesurfacearoundthedefect.WidthofmagneticparticlepatternWidthofdefectToenabletheformationoapropermagneticparticlepatternfordefectindication,theorientationofthedefectandmagneticfieldmustbetakenintoaccount.Twomethodsofmagnetizingtheweldzone.TheYOKEmethodwhichusesanelectromagnetThePRODEmethodinwhichelectrodeareappliedtothespecimentoallowcurrenttoflowinthespecimen. -notapplicabletohightensilesteelsinceitcanformashortcircuitbetweenspecimenandelectrodescausingadefectresemblinganarcstrikes. -effectivetodetectingdefectsnotexposedbutexistingnearthesurface.Twotypesofmagneticparticles:FluorescenttypeNonfluorescenttypeMethodsofparticleapplication:Wetmethod–magneticparticlesaredispersedbysuspensioninwaterorkeroseneandthesuspensionisappliedtothespecimensurface.Drymethod–magneticparticlearedispersedinthesurfaceofthespecimen.MAGNETICPARTICLEMainlyforsurfacedefectsSomesubsurfacedefectscanbefoundOnlyferrousmetalUltrasonictesting(UT)Ultrasonictesting(UT)isamethodofdeterminingthesizeandlocationofdiscontinuitieswithinacomponentusinghighfrequencysoundwaves.Soundwavesaresentthroughatransducerinto

thematerialandtheshiftintimerequirefortheirreturnorechoisplotted.Ultrasonicwaveswillnottravelthroughairthereforeflawswillaltertheechopattern.ULTRASONICoscilloscopeAdvantages:Timetoinspect–fastresponse/abilitytoinspectfromoneside.B.Cost-$3,500.00machine/$200.ootransducerPortablewithbatterypackAccuracycanlocatesmalldiscontinuityLimitations:EquipmentOperatorStandardsReportsandrecordsRadiographicTest(RT)RadiographicTestisaNDTthatcandetectsurfaceandinternaldiscontinuitiesusingelectromagneticradiationofshortdurationbymeansofeither 1.X-Ray 2.GammaRayItisawaveofenergythatwillpassthroughmostmaterialsanddevelopthenegativeimageofwhatitpassesthroughonfilm.Bothofthesemethodsareadangertohealth

1.AnX-Ray-Iselectronicallyproducedinavacuumtube.

2.GammaRay-areemittedbytheatomicdecay.TwoCommonSourceofGammaRays.Cobalt60Iridium1923.FILMVIEWERPicturestakenareviewedasnegativeswillonlygiveflatimagenotinthreedimensionaldarkenedareamustbeusedforviewing.X-RAYX-RAYVIEWERPicturestakenareviewedasnegativeswillonlygiveflatimagenotinthreedimensionaldarkenedareamustbeusedforviewingLimitations:ThenecessitytohaveaccesstobothsidesofthepartbeingradiographedUnfavorableshapeandorientationofsomediscontinuities.RadiationSafetyrequirementsforpersonalprotection.TightCracks,unlesstheyareessentiallynormaltotheradiationbeam.Shallowtightsurfacecracksinthicksectionsusuallycannotbedetectedatall,evenwhenproperlyoriented.Laminationsarenearlyimpossibletodetectbecausetheirorientationdoesnotpermitsufficientdifferencesintheamountofradiationabsorbedthroughthepiecebeingexaminedtoshowthedefectonfilm.Advantages:ARadiograph(X-Raypicture)isapermanentrecordofaweldusedforqualityinspectionpurposesRTinspections