ASTM E213-2004

StandardPracticefor

UltrasonicExaminationofMetalPipeandTubing1ThisstandardisissuedunderthefixeddesignationE213;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.

1.Scope

1.1Thispractice2coversaprocedurefordetectingdiscon-tinuitiesinmetalpipeandtubingduringavolumetricexami-nationusingultrasonicmethods.Specifictechniquesoftheultrasonicmethodtowhichthispracticeappliesincludepulse-reflectiontechniques,bothcontactandnon-contact(forexample,asdescribedinGuideE1774),andanglebeamimmersiontechniques.Artificialreflectorsconsistingoflongi-tudinal,and,whenspecifiedbytheusingpartyorparties,transversereferencenotchesplacedonthesurfacesofareferencestandardareemployedastheprimarymeansofstandardizingtheultrasonicsystem.

1.2Thispracticeisintendedforusewithtubularproductshavingoutsidediametersapproximately1⁄2in.[12.7mm]andlarger,providedthattheexaminationparameterscomplywithandsatisfytherequirementsofSection12.Theseprocedureshavebeensuccessfulwithsmallersizes.Thesemaybespeci-fieduponcontractualagreementbetweentheusingparties.Theseproceduresareintendedtoensurethatproperbeamanglesandbeamshapesareusedtoprovidefullvolumecoverageofpipesandtubes,includingthosewithlowratiosofoutsidediameter-to-wallthickness,andtoavoidspurioussignalresponseswhenexaminingsmall-diameter,thin-walltubes.

1.3TheprocedureinAnnexA1isapplicabletopipeandtubingusedinnuclearandotherspecialandsafetyapplica-tions.TheprocedureinAnnexA2maybeusedtodeterminethehelicalscanpitch.

1.4Thispracticedoesnotestablishacceptancecriteria;theymustbespecifiedbytheusingpartyorparties.

1.5Thevaluesstatedininch-poundunitsaretoberegardedasstandard.TheSIequivalentsareinbracketsandmaybeapproximate.

1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-ThispracticeisunderthejurisdictionofASTMCommitteeE07onNonde-structiveTestingandisthedirectresponsibilityofSubcommitteeE07.06onUltrasonicMethod.

CurrenteditionapprovedJanuary1,2004.PublishedFebruary2004.Originallyapprovedin1963.Lastpreviouseditionapprovedin2002asE213-02.2ForASMEBoilerandPressureVesselCodeapplicationsseerelatedPracticeSE-213intheCode.

1priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.

2.ReferencedDocuments2.1ASTMStandards:3E543PracticeforEvaluatingAgenciesthatPerformNon-destructiveTesting

E1065GuideforEvaluatingCharacteristicsofUltrasonicSearchUnits

E1316TerminologyforNondestructiveExaminationsE1774GuideforElectromagneticAcousticTransducers(EMATs)

E1816PracticeforUltrasonicExaminationsUsingElectro-magneticAcousticTransducer(EMAT)Techniques2.2ASNTDocuments:

RecommendedPracticeSNT-TC-1AforNondestructiveTestingPersonnelQualificationandCertification4ANSI/ASNTCP-1StandardforQualificationandCerti-ficationofNondestructiveTestingPersonnel42.3MilitaryStandards:

MIL-STD-410NondestructiveTestingPersonnelQualifica-tionandCertification52.4AerospaceIndustriesAssociationDocument:

NAS410CertificationandQualificationofNondestructiveTestingPersonnel63.Terminology

3.1Definitions—Fordefinitionsoftermsusedinthisprac-tice,seeTerminologyE1316.

4.SummaryofPractice

4.1Apulsedultrasonicanglebeambymeansofnon-contact,surfacecontactorimmersionmethodshallbeused.Fig.1illustratesthecharacteristicultrasonicanglebeamentry

ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.4AvailablefromAmericanSocietyforNondestructiveTesting,Inc.,1711ArlingateLane,Columbus,OH43228.5AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700RobbinsAve.,Philadelphia,PA19111-5094,Attn:NPODS.6AvailablefromAerospaceIndustriesAssociationofAmerica,Inc.,1250EyeSt.NW,WashingtonD.C.20005.

3Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.

1

FIG.1CircumferentialPropagationofSoundinaPipeorTubeWall

intothewallofapipeortubeinthecircumferentialdirectiontodetectlongitudinaldiscontinuitiesusingasinglesearchunit.Fig.2illustratesthecharacteristicanglebeamultrasoundentryintothewallofapipeortubeintheaxialdirectiontosearchfortransversediscontinuitiesusingasinglesearchunit.

NOTE1—Theimmersionmethodmayincludetanks,wheelsearchunits,orsystemsthatusestreamsorcolumnsofliquidtocoupletheultrasonicenergyfromthesearchunittothematerial.

4.2Toensuredetectionofdiscontinuitiesthatmaynotprovideafavorableresponsefromoneside,scanningshallbe

performedinbothcircumferentialdirectionsforlongitudinaldiscontinuitiesandwhenanaxialscanisspecifiedbytheusingpartyorparties,inbothaxialdirectionsfortransversediscon-tinuities.

4.3Forefficientexaminationoflargequantitiesofmaterial,multiplesearchunitsandinstrumentsmaybeusedsimulta-neouslytoperformscanningintherequireddirections.Mul-tiplesearchunitsmaybeemployedfor“interlaced”scanningineachrequireddirectiontoenablehigherexaminationratestobeachievedthroughhigherallowablescanindexor“pitch.”

FIG.2AxialPropagationofSoundinaPipeorTubeWall

5.SignificanceandUse

5.1Thepurposeofthispracticeistooutlineaprocedurefordetectingandlocatingsignificantdiscontinuitiessuchaspits,voids,inclusions,cracks,splits,etc.,bytheultrasonicpulse-reflectionmethod.

6.BasisofApplication

6.1Thefollowingareitemsthatmustbedecideduponbytheusingpartyorparties.

6.1.1Sizeandtypeofpipeortubingtobeexamined,6.1.2Additionalscanningfortransversediscontinuities,6.1.3Itemsthataffectexaminationcoveragemayalsobespecifiedsuchasscanoverlap,pulsedensityandmaximumsearchunitsize.

6.1.4Thestage(s)inthemanufacturingprocessatwhichthematerialwillbeexamined,6.1.5Surfacecondition,

6.1.6Maximumtimeintervalbetweenequipmentstandard-izationchecks,ifdifferentfromthatdescribedin13.2andthetolerancetobeappliedtoastandardizationcheck,

6.1.7Type,dimensions,location,methodofmanufacture,andnumberofartificialreflectorstobeplacedonthereferencestandard,

6.1.8Method(s)formeasuringdimensionsofartificialre-flectorsandtolerancelimitsifdifferentthanspecifiedinSection11,

6.1.9Criteriaforreportableandrejectableindications(ac-ceptancecriteria),

6.1.10Reexaminationofrepaired/reworkeditems,ifre-quiredorpermitted,shallbespecifiedinthecontractualagreement.

6.1.11Requirementsforpermanentrecordsoftheresponsefromeachtube,ifapplicable,

6.1.12Contentsofexaminationreport,

6.1.13Operatorqualificationsandcertification,ifrequired,6.1.14QualificationofNondestructiveAgencies.Ifspeci-fiedinthecontractualagreement,NDTagenciesshallbequalifiedandevaluatedasdescribedinPracticeE543.TheapplicableeditionofPracticeE543shallbespecifiedinthecontractualagreement.

6.1.15Levelofpersonnelqualification.(See7.1)7.PersonnelQualification

7.1Ifspecifiedinthecontractualagreement,personnelperformingexaminationstothisstandardshallbequalifiedinaccordancewithanationallyrecognizedNDTpersonnelquali-ficationpracticeorstandardsuchasANSI/ASNT-CP-1,SNT-TC-1A,MILSTD-410,NAS-410,orasimilardocumentandcertifiedbytheemployerorcertifyingagency,asappli-cable.Thepracticeorstandardusedanditsapplicablerevisionshallbeidentifiedinthecontractualagreementbetweentheusingparties.

NOTE2—MILSTD-410iscanceledandhasbeenreplacedwithNAS-410,however,itmaybeusedwithagreementbetweencontractingparties.

8.SurfaceCondition

8.1Allsurfacesshallbecleanandfreeofscale,dirt,grease,paint,orotherforeignmaterialthatcouldinterferewith

interpretationofexaminationresults.Themethodsusedforcleaningandpreparingthesurfacesforultrasonicexaminationshallnotbedetrimentaltothebasemetalorthesurfacefinish.Excessivesurfaceroughnessorscratchescanproducesignalsthatinterferewiththeexamination.

9.Apparatus

9.1Instrumentsshallbeofthepulseechotypeandshallbecapableofdetectingthereferencenotchesofthetypesde-scribedinSection11totheextentrequiredinthestandardiza-tionproceduredescribedinSection12.Anindependentchan-nel(orchannels)ofinstrumentationshallbeemployedtoindividuallymonitortheresponsesfromthelongitudinaland,whenrequired,transverseorientedsearchunits.Theinstrumentpulserepetitionrateshallbecapableofbeingadjustedtoasufficientlyhighvaluetoensurenotchdetectionatthescanningrateemployed.Theinstrumentshallbecapableofthispulserepetitionratewithoutfalseindicationsduetospuriousreflec-tionsorinterferencefromotherinstrumentsandsearchunitsbeingusedforsimultaneousexaminationsinotherdirectionsoralongotherscanpaths.

9.1.1Thefrequencyandbandwidthoftheinstrumentandsearchunitshallbecapableofbeingselectedtoproduceasatisfactorysignal-to-noiseratioforthedetectionofthere-quirednotchesascomparedtobackground“noise”responsefromirregularitiessuchasgrainboundariesandsurfacerough-ness.

9.2Searchunitfrequencyshallbeselectedtoproduceadesirable“signal-to-noise”ratio(S/N),fromthematerialtobeexamined,atthespecifiedsensitivity.AS/Nvalueofatleast3to1isusuallyconsideredtobeminimum.Ahigherminimumvalueisdesirableandmaybespecifiedbythecontractingagency.

9.2.1Selectasearchunitsize,frequencyandrefractedangle(orcorrespondingparametersfornon-contacttechniques)toproduceanapproximate45degreesbeam-centershearwaveinthetubeorpipewall.Formaterialwithanoutsidediameter-to-thicknessratiolessthan7,alowerrefractedangle(orcorrespondingparametersfornon-contacttechniques)mustbeusedtoensureintersectionwiththeinsidesurface.Thisdoesnotensuredetectionofmidwalldiscontinuities[SeeReference5].

9.3Thepositionsofallconveyoranddrivemechanismsmustbesettosupportandfeedthematerialtobeexaminedinastablemannerandatthedesiredscan“pitch”(helix).Forsmalltubes,supportmechanismsmustbeusedintheexami-nationstationtopreventanytransversemotionwithrespecttothesearchunitbeamduringscanning.Iflargermaterialthatisnotstraightistobeexaminedthesearchunitsmayhavetobesupportedina“follower”mechanismtocompensateforthis.10.Couplant

10.1Forpiezoelectric-basedsearchunits(non-contacttech-niquesdonotrequirecouplant),acouplantsuchaswater,oil,orglycerin,capableofconductingultrasonicvibrationsbe-tweenthesearchunitandthepipeortubebeingexaminedshallbeused.Rustinhibitors,softeners,andwettingagentsmaybeaddedtothecouplant.Thecouplantliquidwithalltheadditivesshouldnottobedetrimentaltothesurfacecondition

ofthepipeortube,andshallwetthesurfaceofthematerialtoprovideadequatecouplingefficiency.Topreventspurioussignalsorlossofsensitivity,orboth,caremustbetakentoavoidthepresenceofairbubblesinthecouplant.

NOTE3—Inthecontactmethod,somecouplantsresultinbetterultrasonictransmissionwhenthetubingisprecoatedseveralhoursbeforetheexamination.

11.ReferenceStandards

11.1Areferencestandardofaconvenientlengthshallbepreparedfromalengthofpipeortubeofthesamenominaldiameter,wallthickness,material,surfacefinish,andacousti-calpropertiesasthematerialtobeexamined.Thereferencepipeortubeshallbefreeofdiscontinuitiesorotherconditionsproducingindicationsthatcaninterferewithdetectionofthereferencenotches.

11.2Longitudinaland,whenrequiredbythecontractingagency,transversereferencenotchesshallbeplacedonboththeoutsideandinsidesurfacesofthereferencestandardtoensuresatisfactoryexaminationsensitivityneareachoftheseboundaries.

11.3Referencenotchesshallbeseparatedsufficiently(cir-cumferentiallyoraxially,orboth)toprecludeinterferenceandinterpretationdifficulties.

11.4Allupsetmetal,burrs,etc.,adjacenttothereferencenotchesshallberemoved.

11.5Thenotchdimensions,whicharelength,depth,andwidth(andforV-notches,theincludedangle)mustbedecideduponbytheusingpartyorparties.Fig.3illustratesthecommonnotchconfigurationsandthedimensionstobemea-sured(Note4).ReflectionamplitudesfromV-,square-,andU-shapednotchesofcomparabledimensionsmayvarywidelydependingontheangle,frequency,andvibrationalmodeoftheinterrogatingsoundbeam.

NOTE4—InFig.3(a),(b),and(d),thesharpcornersareforeaseofillustration.Itisrecognizedthatinnormalmachiningpractice,aradiuswillbegenerated.

11.5.1Thenotchdepthshallbeanaveragemeasuredfromthecirculartubingsurfacetothemaximumandminimumpenetrationofthenotch.Measurementsmaybemadebyoptical,replicating,orotheragreedupontechniques.Unlessspecifiedotherwisebytheusingpartyorparties,thenotchdepthshallbewithin60.0005in.[0.013mm]ofthespecifiedvaluefornotches0.005in.[0.13mm]orlessindepth,andwithin+10,−15%ofthespecifiedvaluefornotchesover0.005in.indepth.Attheoptionofthetestingagency,shallowernotchesmaybeusedtoprovideamorestringentexamination.

NOTE5—Foras-rolledorscalypipeortubesurfaces,itmaybenecessarytomodify11.5.1.Twoacceptablemodificationsarelistedbelow.Modification(a)ispreferred;however,modification(b)maybeusedunlessotherwisespecified.

(a)(b)

Thecircularpipeortubesurfacemaybesmoothedorpreparedinthenotcharea,or

Thenotchdepthshallbewithin60.001in.[0.025mm],or+10,−15%ofthespecifieddepth,whicheverisgreater.

11.5.2Whennotchtolerancesarespecifiedbytheusingpartyorparties,tolerancesmayoftenincludeonlynegativevalueswithzeropositivedeviationallowedsothatsensitivityisneverreducedbelowaspecifiedminimumvalue.Theuseofsmallernotchesbytheexaminationagencyispermissible,providedthatconcurrenceisobtainedfromthecontractingagency.

NOTE6—Theamplitudeofindicationsobtainedfromreferencenotchesmaynotbelinearlyproportionaltonotchdepth.Thisdependsupontheinterceptingbeamwidthtonotchlength.

11.5.3Thewidthofthenotchesshallbeassmallaspractical,butshouldnotexceedtwicethedepth.

11.6Othertypesandorientationsofreferencereflectorsmaybespecifiedbytheusingpartyorparties.

12.StandardizationofApparatus

12.1StaticStandardization—UsingthereferencestandardspecifiedinSection11,adjusttheequipmenttoproduceclearly

FIG.3CommonNotchShapes

identifiableindicationsfromboththeinnerandoutersurfacenotches.Theresponsefromtheinnerandoutersurfacenotchesshouldbeasnearlyequalaspossible.Usethelesserofthetworesponsestoestablishtherejectionlevel.Onlargediameterorheavywallpipeandtubing,iftheinnerandoutersurfacenotchamplitudecannotbemadeequalbecauseofmaterialsoundpathdistanceandinsidediametercurvature,aseparaterejectionlevelmaybeestablishedfortheinnerandoutersurfacenotches.

NOTE7—Distance-AmplitudeCorrection—Amethodofcompensatingforthereductioninultrasonicsignalamplitudeasafunctionofmaterialsound-pathdistancemaybeemployed.Detailsoftheproceduresusedtoestablishandapplythedistance-amplitudecorrection(DAC)curveshallbeestablishedbytheusingpartyorparties.

12.2DynamicStandardization—Standardizetheequipmentunderdynamicconditionsthatsimulatetheproductionexami-nation.Thepipeortubingtobeexaminedandthesearchunitassemblyshallhavearotatingtranslatingmotionrelativetoeachothersuchthatahelicalscanpathwillbedescribedontheoutersurfaceofthepipeortube.Maintainthespeedofrotationandtranslationconstantwithin610%.Axialscanningwithcircumferentialindexingmaybeusedtoprovideequivalentcoverage.

12.3Thepitchofthefeedhelixshallbesmallenoughtoensureatleast100%coverageattheexaminationdistanceandsensitivityestablishedduringstandardization.Coverageshallbebaseduponthemaximumeffectivesizeofthesearchunit,thepulsedensityforeachinstrumentchannelandthehelix.13.Procedure

13.1Examinethepipeortubingwiththeultrasoundtrans-mittedinbothcircumferentialdirectionsforlongitudinaldis-continuitiesand,whenspecified,inbothaxialdirectionsfortransversediscontinuities,underidenticalconditionsusedforequipmentstandardization(seeNote8).

NOTE8—Identicalconditionsincludeallinstrumentsettings,mechani-calmotions,searchunitpositionandalignmentrelativetothepipeortube,liquidcouplant,andanyotherfactorsthataffecttheperformanceoftheexamination.

NOTE9—Ifarequirementexistsforbothlongitudinalandtransversenotchesthefollowingthreeoptionsareavailable:

(a)Eachpipeortubeispassedthroughasingle-channelexaminationstationfourtimes,twiceineachdirection,

(b)Eachpipeortubeispassedthroughatwo-channelexaminationstationtwice,onceineachdirection,or

(c)Eachpipeortubeispassedthroughafour-channelexaminationstationonce.

13.2StandardizationChecks—Periodicallycheckthedy-namicstandardizationoftheequipmentbypassingtherefer-encestandardthroughtheexaminationsysteminaccordancewith12.2.Makethesecheckspriortoanyexaminationrun,priortoequipmentshutdownafteranexaminationrun,andatleasteveryfourhoursduringcontinuousequipmentoperation.Restandardizetheequipmentinaccordancewith12.1and12.2anytimetheequipmentfailstoproducethesignalamplitudesorotherconditionsforrejectionwithinthetolerancesagreeduponwiththecontractingagency.Intheeventthattheequipmentdoesnotmeetthisrequirement,reexamineallpipe

ortubingexaminedsincethelastacceptablestandardizationafterrestandardizationhasbeenaccomplished.

13.2.1Whenrequiredbythepurchaser,morespecificre-standardizationcriteriamaybespecified.

13.3Formanytubularsizesandexaminationarrangements,therewillbeareflectionfromtheentrysurfaceofthepipeortube.Thissignalmaybeobserved,butnotgated,asasupplementtotherequiredcheckingofthereferencestandardtoprovideincreasedassurancethattheequipmentisfunction-ingproperly.Ifsuchasignaldoesnotexist,makemorefrequentequipmentstandardizationchecks.

13.4Donotmakeanyequipmentadjustments,duringex-amination,unlessthecompletestandardizationprocedurede-scribedinSection12isperformedafteranysuchadjustment.13.5Theexaminationshallbeappliedto100%ofthepipeortubingunlessotherwisespecified.

NOTE10—Sometraversingmechanismsdonotallowexaminationofpipeortubeends.Whenthisconditionexists,clearlyindicatetheextentofthiseffect,pertube,intheexaminationreport.

14.InterpretationofResults

14.1AllindicationsthatareequaltoorgreaterthantherejectionlevelestablishedduringstandardizationasdescribedinSection12,usingtheagreeduponreferenceindicatorsdescribedin11.5,shallbeconsideredasrepresentingdefectsandmaybecauseforrejectionofthepipeortube.Alterna-tively,theusingpartyorpartiesmayspecifyspecificaccep-tancecriteria.

14.2If,uponfurtherexaminationofthepipeortube,norejectableindicationsaredetected,thematerialshallbecon-sideredashavingpassedtheultrasonicexamination,exceptasnotedin13.2.

NOTE11—Rejectedpipeortubesmaybereworkedinamanneracceptabletothepurchaser.If,uponultrasonicreexaminationofthereworkedpipeortube,norejectableindicationsaredetected,thematerialshouldbeconsideredashavingpassedtheultrasonicexamination.

NOTE12—Careshouldbeexercisedtoensurethatreworkingapipeortubedoesnotchangeitsacceptabilitywithrespecttootherrequirementsofthematerialspecificationsuchaswallthickness,ovality,surfacefinish,length,andthelike.

15.Documentation

15.1Whenareportisrequired,itshallcontainsuchinformationasismutuallyconsideredadequatetodocumentthattheexaminationofthepipeortubessuppliedmeetstherequirementsofthispractice,andanymodificationsspecifiedinthecontractualagreement.

15.2Whena“thirdparty”examinationisrequired,asmightbeperformedbyanindependentexaminationfacility,andtotheextentspecifiedinthecontractualagreement,apermanentrecordcontainingobjectiveevidenceoftheexaminationresultsshallbeobtainedforpipeortubeexamined.Thismaybeintheformofastripchartrecordingorcomputerizeddataoftheultrasonicinstrumentoutputduringtheexamination.Itshallcontainrecordingsofallstandardizationsandstandardizationchecksandshouldbeannotatedtoprovideapositivecorrela-tionbetweenexaminationrecordforeachrejectpipeortubeandthecorrespondingpipeortube.Thesuppliershallmaintainareportoftheexaminationonfile.Whenrequestedbythe

customer,areportoftheexaminationshallbesubmittedtothecustomer.Thereportshallincludeatleastthefollowinginformation:

15.2.1Identificationofthematerialbytype,size,lot,heattreatment,andanyotherpertinentinformation.

15.2.2Identificationoftheexaminationequipmentandaccessories.

15.2.3Detailsoftheexaminationtechnique,includingex-aminationspeed,examinationfrequency,andendeffectsifany.15.2.4Descriptionofthereferencestandard,includingtheactual(measured)dimensionsoftheartificialreferencereflec-tors.

15.2.5Descriptionofthedistance-amplitudecorrectionpro-cedure,ifused.

15.2.6Examinationresults.16.Keywords

16.1anglebeam;nondestructiveexamination;pipe;tubing;ultrasonicexamination

ANNEXES

(MandatoryInformation)

A1.EXAMINATIONOFPIPEANDTUBINGFORSPECIALANDSAFETYAPPLICATIONS

A1.1Introduction—Whentheenduseofpipeortubingdependscriticallyuponfreedomfromdiscontinuitiesoveracertainmaximumsize,certainadditionalultrasonicexamina-tionproceduresarerequiredtoassurethattherequiredqualitystandardsaremet.Theimmersionmethodisalmostalwaysrequiredforexaminingtubesfortheseuses.Insomeinstances,suchasfieldexaminationorwherepartcontactwithwaterisundesirable,thecontactmethod,ornon-contacttechnique,forinstanceasdescribedinGuideE1774,maybeemployed.A1.1.1Thispracticeisintendedforusewithtubularprod-uctsofanydiameterandwallthickness,providedthatproperprocedures,asdescribedherein,arefollowed.Theseproce-duresareintendedtoensurethatproperrefractionanglesandbeamshapesareusedtoprovidefullvolumecoverageofpipesandtubes,includingthosewithlowratiosofoutsidediameter-to-wallthickness,andtoavoidspurioussignalresponseswhenexaminingsmall-diameter,thin-walltubes.

A1.2SummaryofPractice—Pulsedultrasonicanglebeamsbyeitherthesurfacecontactorimmersionmethodshallbeused.Fig.A1.1illustratescharacteristicanglebeamultrasoundentryintothewallofapipeortubeinthecircumferentialdirectiontodetectlongitudinaldefectsandintheaxialdirec-tiontodetecttransversedefects,whenrequired.Theincidentandrefractedbeamsinthesecasesarepicturedasbeinggeneratedbyacylindricallyfocusedimmersionsearchunit.Inpipesandtubeswithdiametersseveraltimeslargerthanthelengthofacontactsearchunit,thegeneralbeamshapesareapproximatelythesame.

A1.3AdditionalApparatusRequirements

A1.3.1Althoughcontactsearchunitsmaybeusedforsmallquantityandfieldexaminationsofpipesandtubes,cylindri-cally(line)focusedimmersionsearchunitsarepreferredforcriticalexaminationsandforlargerquantities(SeeReferences(1),(3)and(4)).Searchunitelementsizeandfocusedbeamlengthshallbesuitableforachievingreliabledetectionofdefectsequivalentinsizetothereferencenotchesatthe

scanningpitchorindexused.Whenexaminationofheavy-wallpipesandtubesisrequiredthefocallength,refractionangleandincludedbeamangleoffocusedsearchunitsshallbesuitableforcompletethrough-wallcoverage(See(5)).

A1.3.2Thebeamlengthofthesearchunitinthewallmaterialmustbeeitherlongerorshorterthanthelengthoflongitudinalnotchesinthereferencestandard,byanamountthatisnolessthanthe“pitch”(linearadvanceperrevolution)ofthehelicalscanpath(seeA2.1).Thisisnecessarytoensuredetectionofdiscontinuitiesthatareaslongasthenotchesinspiteoftheirrandomlocationswithrespecttothescanpath,(SeeAnnexA2).

A1.3.3Thefocallengthofafocusedimmersionsearchunitshouldequalthepipeortuberadiusplusaconvenientwaterpathlengthsothatitmaybefocusedonthepipeortubecenterline(See(4)).

A1.3.4Theangleofthecentralbeamofthesearchunit,withrespecttoaperpendiculartothetangenttothesurfaceatthepointofbeamincidence,shallbeadjustedtoproduceasuitablerefractionangleinthepipeortubewalltoprovidecompletecoverageofthepipeortubewallthickness(See(5)).Arefractionangleof45degreesistypicallyusedwhenexaminingpipeortubeswithadiameter-to-wallthicknessratioofnolessthanabout10to1.Formanymaterialsa45degreerefractionanglemaybeachievedwithabeamincidenceangleofabout18to19degrees.Thismaybeachievedintheimmersionmethodbyparalleloffsettingthebeamcenterlinefromaperpendiculartoatangentofthesurfacebyadistanceequalto1⁄6oftheoutsidediameterofthepipeortube.Thisisoftenaconvenientinitialadjustmentduringsystemstandard-ization.

A1.4AdditionalReferenceStandardRequirements

A1.4.1Outersurfaceandinnersurfacelongitudinalrefer-encenotchesmaybeplacednearoneendofthereferencestandardseparatedbyasufficientdistancefromeachotherandfromtheendtoprecludeinterferenceandinterpretationdiffi-culties,butcloseenoughtoeachothertominimizethetime

FIG.A1.1BeamPropagationinPipeorTubeWalls

requiredinscanningfromonetoothertoachievegoodsignalbalanceduringset-up.Foreaseoffabrication,theinnersurfacenotchshouldbenearertheendofthepipeortube.Whenrequired,transverseoutersurfaceandinnersurfacereferencenotchesaretypicallyplacedinthesamemannerneartheoppositeendofthereferencestandardfromthelongitudinalnotches.Althoughnotmandatory,thispracticeenablesallnotchestobeplacedfarenoughfromtheendstoinsuregoodsupportofthematerialendnearestthesearchunit(s)duringset-up,andtheinnersurfacenotchestobenearendstofacilitateinsertionofthefabricationandverificationmeans.Thisprocedurebecomeslesscriticalformaterialoflargerdiametersandstiffness.

A1.5StaticStandardization—UsingthereferencestandardspecifiedinSection11,adjusttheequipmenttoproduceclearlyidentifiableindicationsfromboththeinnerandoutersurfacenotches.Therelativeresponsesfromboththeinnerandoutersurfacenotchesshouldbeasnearlyequalaspossibleandpractical.Somedifferencesinthisprocedurearerequired,asdescribedbelow,dependinguponwhetherthecontactorimmersiontechniqueisemployed.

A1.5.1Setthepositionsofallconveyoranddrivemecha-nismstosupportandfeedthematerialtobeexaminedinastablemannerandatthedesiredscan“pitch”,consideringconditionsforachievingsatisfactory“worstcaseinterception”andrequiredscanpathoverlap.(SeeAnnexA2.)

A1.5.2ContactExaminationTechnique—Forfieldexami-nation,orinothercaseswhereimmersionexaminationisnotpractical,thecontacttechniquemaybeemployed.Itisimpor-tanttonotehoweverthatitismoredifficulttoobtainrepeatableandaccurateresultswiththistechniquebecause(See(1)):

(a)Itisdifficulttomaintainuniformsensitivityduringscanningduetolackofconstantpressureonthesearchunitandinconsistentcouplantcoverage;

(b)Unlessspecial“involute”(2),orsimilar,searchunitsareuseditisimpossibletoobtaintheprimarybenefitoffocusingwhichistheuniformityofsensitivityversusthicknesswhichresultsfromtheproductionofconstantrefractionanglesthroughoutthewidthofthebeam;

(c)Withagivensearchunitwedgeitisimpossibletovarytheincidentangletoachievegoodbalanceofthesignalsfromoutersurfaceandinnersurfacenotchtargetsortolowertheincidenceangletoobtaingoodthrough-wallcoverageonthick-wallpipeortubes;

(d)Maintenanceproblemsmayresultfromwearofthesearchunitfaceplates;and,

(e)Whenmanualscanningisemployeditisdifficulttoinsurethattotalsurfacecoverageoranyprescribedamountofscanoverlaphasbeenachieved.

A1.5.3Whencontactexaminationisperformed,thefollow-ingselectionandstandardizationprocedureshallbeusedunlessanalternateprocedureisapprovedbythecontractingagency.

(a)Selectasearchunitsize,frequencyandwedgeangleandshapetoproduceanapproximately45degreebeam-centershearwaveinthetubeorpipewall.Ifitisdeterminedthatalowerrefractionanglewouldbebeneficial,awedgetoproducethatanglemaybeused.(b)Applythesearchunit,withasuitablefilmofcouplant,tothesurfaceofthereferencestandardinthevicinityofthelongitudinalreferencenotches.Directthesearchunitbeaminonecircumferentialdirection.

(c)Whilecarefullymaintaininguninterruptedcouplingandconstantpressureonthesearchunit,moveittowardandawayfromtheoutersurfacelongitudinalnotchtoachievethemaximumsignalresponsefromitbyabeamreflectionfromtheinnersurfacewhichisbeyondtheinterfacesignalonthedisplayscreenoftheinstrument.Adjustthegaincontroltosetthepeakresponseatthisreflectionlocation(node)to80%offullscreenheight(FSH).

(d)WithoutchangingthegaincontrolsettingfromthatdeterminedinStep(c)above,movethesearchunittothevicinityoftheinnersurfacelongitudinalnotchandrepeatthescanningprocedureuntilthesignalfromthatnotch,atanodeadjacenttothatusedfortheoutersurfacenotchsignal,ismaximum.Recordthepeakamplitudeofthesignalfromtheinnersurfacenotch.Ifthissignalishigherthan80%FSH,lowerthegaintobringitto80%FSHandmoveagaintotheoutersurfacenotchandrecorditspeakamplitudeatthenewgainsetting.Therelativeresponsefromtheinnerandoutersurfacenotchesshallbeasnearlyequalaspossiblebyselectionofthepairofadjacentinnersurfaceandoutersurfacenotchsignalnodesareobserved.Usethelesserofthetworesponsestoestablishtherejectionlevel.Onlarge-diameterorheavy-wallpipeandtubing,iftheinnerandoutersurfacenotchsignalamplitudescannotbeequalizedbecauseofmaterialsoundpathdistanceandinsidediametercurvature,aseparaterejectionlevelmaybeestablishedfortheinnerandoutersurfacenotches,or,inthiscase,DACmaybeusedtobalancethesignalamplitudesfromtheoutersurfaceandinnersurfacenotches.

(e)Repeatsteps(a)through(d)whilescanningfromtheoppositecircumferentialdirection.

(f)Repeattheabovestepswhilescanninginbothaxialdirectionsifdetectionoftransversenotchesanddiscontinuitiesisrequiredbytheuserorcontractingagency.

A1.5.4ImmersionExaminationTechnique—Thisisthepre-ferredtechniquewheneverpractical(1).AnyoftheapparatustypeslistedinNote1(4.1)maybeusedforthispurpose.Thefollowingselectionandstandardizationprocedureshallbeusedunlessanalternativeisapprovedbythecontractingagency.A1.5.5Usingtheguidelineslistedbelow,selectacylindri-callyfocused(linefocused)searchunit(3)ofappropriatefrequency,beamlengthandfocallengthforthematerialtobeexaminedandtothesensitivitylevel(notchsizes)specifiedbytheuserorcontractingagency.Incaseswherethetypeofexamination,materialdimensionsorotherpropertiesmaketheuseofsphericallyorflatfocusedsearchunitsmoreappropriateeitherofthesetypesmaybeusedinplaceofcylindricallyfocusedunits.

(a)Thefrequencyshallbeselectedtoproduceadesirablesignal-to-“noise”ratio(S/N)fromthematerialtobeexaminedatthespecifiedsensitivity.AS/Nvalueofatleast3to1isusuallyconsideredtobeaminimum.Ahigherminimumvalueisdesirableandmaybespecifiedbythecontractingagency.

(b)Thefocallengthmustbeequaltothepipeortuberadiusplusaconvenientwaterpathlengthsothatthesearchunitmaybefocusedonthecentralaxisofthepipeortubeafternormalization(4).Forverylarge-diametermaterialwherethisrequirementisfoundtobeimpracticalsearchunitsofotherfocallengthsorunfocusedunitsmaybeused.

(c)Thebeamwidth,asmeasuredbetween-3dBpointsonapulse-echoprofileasdescribedinGuideE1065,mustbeeitherlongerorshorterthanthelengthofthelongitudinalnotchesinthereferencestandardbytheamountofthescanpitchtobeemployed.Thisisnecessarytoensureconsistent“worstcase”interceptionofdiscontinuitiesthatareaslongasthenotchesinspiteoftheirrandomlocationwithrespecttothescanpath.(SeeAnnexA2.)

(d)Positionthesearchunitsothatthelengthofitsfocusedbeamisalignedwiththelongaxisofthepipeortube.

(e)Withthewaterpathlengthadjustedtofocusthebeamapproximatelyontheoutersurfaceofthepipeortube,normalizethesearchunitbyadjustingitsangulationandoffsettopeakitsresponsefromthesurface.

(f)Changethewaterpathsothatitisequaltothefocallengthofthesearchunitminustheradiusofthetube.Readjusttheangulationandoffsetifnecessarytorenormalizebyrepeakingtheinterfacesignal.

(g)Offsetthesearchunitinadirectionthatisparalleltoitscenterlineandperpendiculartothelongitudinalaxisofthetubebytheamountrequiredtoestablishabeam-centerincidenceanglethatwillproducethedesiredrefractionangleinonecircumferentialdirectioninthetubewall.(Formanymaterialsasatisfactoryinitialoffsetdistanceis1⁄6ofthetubediameter.)Forthick-walltubesalowerrefractionanglemayberequiredforexaminationoftheentirethickness(5).Alternatively,thesearchunitmaybeangulatedinaplaneperpendiculartothetubeaxistoproducetheincidenceangle.

(h)Movethereferencestandardtocentertheouter-surfacenotchinthesearchunitbeam.Rotatethetubewithouttranslation(thatis,withoutmotionalongitslongitudinalaxis)andobserveontheinstrumentdisplayscreenthemotionofthenotchsignalawayfromanyresidualinterfacesignal.Theamplitudeshoulddecreaseandincreaseassuccessivereflec-tionsofthebeamfromtheinnerandoutersurfacesintersecttheoutersurfacenotchasitmovestovariousnodepositionsawayfromthesearchunit.Selectaconvenientnodewellawayfromthe“direct-in”intersectionofthebeamontheoutersurfacenotch(whichcoincideswiththepositionoftheinterfacesignal).Adjustthegaintosettheamplitudeofthesignalat80%FSHandnoteitshorizontalpositiononthedisplay.

Note—Alternatively,set-upontheinnersurfacenotchmaybeperformedbeforeset-upontheoutersurfacenotch,asdescribedinstep(h)above.Thisinnersurfacenotchsignalmustbewellbeyondthedirect-insignalfromtheoutersurfacenotch.Theoutersurfacenotchsignalsubsequentlyusedforstandardizationshouldthenbefromthenodeimmediatelybeyondtheinnersurfacenotchsignaltoobtainthebestconditionforattemptingtoequalizebothgatedsignalsinthefollowingstep(i).

(i)Movethereferencestandardtocentertheinnersurfacenotchinthebeam.Rotatethepipeortubeasfortheouter

surfacenotchandnotetheamplitudeoftheinnersurfacenotchsignalthatappearsjustbeforetheselectedoutersurfacenotchsignal.

(j)Makesmalladjustmentstotheoffset(orangulation)andtothewaterpathlengthwhilealternatelyobservingandattemptingtoequalizetheoutersurfaceandprecedinginnersurfacenotchsignalamplitudes.Setthehigherofthetwosignalsto80%FSHandusethelesserofthetwosignalstoestablishtherejectionlevel.Setthepositionanddurationoftheinstrumentalarmgatetoincludebothofthesesignals.Forexaminationsthatrequirestoppingandevaluatingormarkingallrelevantindications,orboth,setthealarmactivationthresholdat40%FSH.Recordallsearchunitpositionsettings,instrumentcontrolsettingsandstandardizationsignallevelsonanexaminationrecordsheet.

(k)Repeattheabovestepswhilescanningintheoppositecircumferentialdirection.

(l)Whenaxialscanningfortransverseindicationsisrequired,repeattheabovestepswiththesearchunitangledinfirstone,thentheotheraxialdirectionandusingtranslationratherthanrotationofthereferencestandardtoselectresponsenodesfromoutersurfaceandinnersurfacenotches.A1.6DynamicStandardization—Standardizetheequipmentunderdynamicconditionsthatsimulatetheproductionexami-nation.Thepipeortubingtobeexaminedandthesearchunitassemblyshallhavearotatingtranslatingmotionrelativetoeachothersuchthatahelicalscanpathwillbedescribedontheoutersurfaceofthepipeortube.Maintainthespeedofrotationandtranslationconstantwithin610%.Axialscanningwithcircumferentialindexingmaybeused,especiallyonlargermaterial,toprovideequivalentcoverage.Amethodforachiev-ingtherequiredconditionsisdescribedbelow.

A1.6.1Thepitchoffeedhelixshallbesmallenoughtoensure100%coverageattheexaminationdistanceandsensi-tivityestablishedduringstaticstandardizationperA1.5.AnnexA2describeshowmaximumallowablepitchforstabledetec-tionmaybedeterminedfromthelengthofthelongitudinalreferencenotchesandtheminimumbeamlengthofthesearchunits.

A1.6.2Apreferredmethodfordynamicscanning,appli-cabletoalldiametersbutespeciallyforsmallerdiametermaterial,forexample,lessthan4inches[100mm]indiameter,isfortheexaminationsystemtoproducearotatingandtranslatingrelativemotionbetweenthepipeortubingbeingexaminedandthesearchunit(s).Runthereferencestandardwithrandominitialtranslationalandangularorientationthroughtheexaminationstationatfullspeedandscanpitchandobserve,duringmultiplerunsofthestandard,thestabilityofthegatedalarmsignalsfromallnotchesinthereferencestandardonastrip-chartrecorderorothermeansforobservingsignalamplitudestabilityoralarmfunction.Intheabsenceofanalternateprocedureapprovedbythecontractingagency,thepeaksignalamplitudesmustremainconstantwithin10%FSHforthenumberofsuccessiverunsspecifiedinanapprovedexaminationprocedure(aminimumofsixissuggested)or,ifanotherdefectalarmdeviceisused,itshallprovideconsistent

operationforthespecifiednumberofruns.Ifindexedaxialscanningisused,thesamestabilityverificationprocedureandcriteriashallapply.

A1.7AdditionalMandatoryProcedureRequirementsA1.7.1StandardizationChecks—Periodicallycheckthestandardizationoftheequipmentbypassingthereferencestandardthroughtheexaminationsystem.Makethesecheckspriortoanyexaminationrun,priortoequipmentshutdownafteranexaminationrun,andatleasteveryhourduringcontinuousequipmentoperation.Restandardizeandreexaminethematerialifnecessary,inaccordancewiththefollowingprocedures,unlessotherwisespecifiedbythecontractingagency.

A1.7.2Restandardization—Ifanynotchinthereferencestandardfailstoactuateanalarm,or,wheredefectanalysisismadefromastripchartrecordingofsignalamplitudes,ifthedeviationfromtherecordedamplitudeoftheinitialstandard-izationsignalexceeds10%ofthatamplitude,portionsofthestaticanddynamicstandardizationproceduresofA1.6shallberepeateduntilsatisfactoryoperationisobtained.Thenthefollowingstepsshallbetaken,dependinguponthenatureofthefailure.

A1.7.3FailureofAlarmActuation—Whenalarmactuationistheonlydefectindicationused,ifanotchinthereferencestandardfailstoactuatetheflawalarmduringastandardizationcheck,alllengthsofmaterialrunsincethelastsatisfactorystandardizationcheckshallbereexaminedafterthesystemhasbeensuccessfullyrestandardized.

A1.7.4DecreaseofRecordedNotchSignalAmplitudeofBetween10and20%andNoRecordedIndications—Inthecaseofarecordedexaminationwhereinthesignalamplitudefromanynotchinthererunreferencestandardhasdecreasedfromtheaveragevalueoftheinitiallyrecordedamplitudesbymorethan10%butlessthan20%,norerunofpartsisrequiredafterrestandardizingif,sincethelastsatisfactorystandardizationcheck,therewerenorecordedunrejectedsignalindicationsthatweregreaterthan50%oftheaverageamplitudeoftheinitiallyrecordedsignals.However,restan-dardizationshallbeperformedtobringthesignalamplitudetowithin10%oftheaverageoftheinitiallyrecordedvaluesbeforeexaminationisresumed.

A1.7.5DecreaseofRecordedNotchSignalAmplitudeofOver20%orofBetween10and20%WithIndications

Ifthererunrecordedvalueislessthantheaverageoftheinitialrecordedamplitudesbymorethan20%,orifthedecreaseisbetween10%and20%andthereareunrejectedindicationsofgreaterthan50%oftheaverageinitialstandard-izationamplitude,theentirelotofmaterialexaminedsincethelastsatisfactorystandardizationcheckshallbereexaminedafterrestandardization.

A1.7.6IncreaseofRecordedNotchSignalAmplitude

Ifanyrecordednotchsignalamplitudeisfoundtohaveincreasedbymorethan10%abovetheaverageoftheinitiallyrecordedvalues,restandardizationshallbeperformedtobringthesignalleveltowithinthatrange.Iftheincreaseisbetween10%and20%norerunofmaterialisrequired.Iftheincreaseisgreaterthan20%,andtherehavebeenindicationsrejectedsincethelastsatisfactorystandardizationcheck,theentirelotofmaterialrunsincethelaststandardizationcheckshallbereexamined.

(MandatoryInformation)

A2.RESTRICTIONONTHESELECTIONOFSCANPITCH

A2.1DeterminationofScanPitch—Thehelicalscanpitch,howevergenerated,mustnotexceedtheabsolutedifferencebetweenthelengthofthelongitudinalreferencenotchesandtheeffectivelengthofthesearchunitbeam.Thisrequirementmaybestatedas:

P#|N2B|

interceptionlength,andthereforesignalamplitude,betweenworstandbestinterceptionsmaybeobtainedbydividingIwcbyeither“N”(if“B”islonger)orby“B”(if“N”islonger);thatis:

Iwc/N51/21$B2P%/2N

where:

N=NotchLengthB=BeamLength

A2.1.1Thisrestrictionarisesfromconsiderationofthe“worstcaseinterception”ofthelongitudinalnotch(andthere-foredefectsofthatlength)bythesearchunitbeam,regardlessoftherandominitiallocationofthenotchwithrespecttothescanpattern.Theactuallengthoftheworstcaseinterceptionmayberepresentedby:

Iwc5$N1B2P%/2

or

Iwc/B51/21~N2P!/2B

A2.1.2Thelengthofthe“bestcase”randominterceptionofthenotchbythebeamisequaleitherto“N”or“B”,dependingonwhichislonger.Thefractionalpercentagechangeinnotch

A2.1.3Itisseenfromtheseequationsthatifthepitchisequaltoeitherthebeamlength(ifitisgreaterthanN)ortothenotchlength(ifitisgreaterthanB),thepercentagechangebetweenbestandworstcaserandominterceptionsofthenotchbythebeamwillbe0.5or6dB.Noacceptablestandardizationrepeatabilitycanbeprovidedinthatcase.However,ifP=N-Bissubstitutedinthefirstoftheaboveequations,orP=B-Nissubstitutedinthesecond,theratioofworsttobestcaseinterceptionis1.0.Thisindicatesnosignalvariationduetorandomalignmentandistheprescribedconditionformaxi-mumpitchif“invariant”notchdetectionistobeassured.

REFERENCES

(1)Bar-Cohen,Y.,“IntroductiontoUltrasonicTesting,”NondestructiveTestingHandbook,2ndEd.,Vol.7,pp220,221,1991,Am.Soc.forNondestructiveTesting,Columbus,Ohio.

(2)Toth,J.M.,andB.J.Ross,“TheInvoluteSearchUnit-ANewConceptintheUltrasonicInspectionofPipe,”MaterialsEvaluation,Vol.39,No.9,Aug.1981,pp828-833.

(3)Ensminger,D.,Ultrasonics-Fundamentals,Technology,Applications,

2ndEd.,p296,1988,MarcelDekker,Inc.N.Y.andBasel.

(4)Beck,K.H.,“UltrasonicTransducerFocusingforInspectionofCylin-dricalMaterial,”MaterialsEvaluation,Vol.49,No.7,July1991,pp876-882,ASNT.

(5)Beck,K.H.,“UltrasonicRefractionAnglesforInspectionThroughouttheTotalWallThicknessofTubesandPipes,”MaterialsEvaluation,Vol.51,No.5,May1993,pp607-612,ASNT.

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