ISO 20484-2017 Non-destructive testing - Leak testing - Vocabulary

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INTERNATIONALISOSTANDARD20484Firstedition2017-03Non-destructivetesting—Leaktesting—VocabularyEssaisnon-destructsif—Contrôled’étanchéité—oVcabulaireReferencenumberISO20484:2017(E)©ISO2017 ISO20484:2017(E)COPYRIGHTPROTECTEDDOCUMENT©ISO2017,PublishedinSwitzerlandAllrightsreserved.Unlessotherwisespecified,nopartofthispublicationmaybereproducedorutilizedotherwiseinanyformorbyanymeans,electronicormechanical,includingphotocopying,orpostingontheinternetoranintranet,withoutpriorwrittenpermission.PermissioncanberequestedfromeitherISOattheaddressbeloworISO’smemberbodyinthecountryoftherequester.ISOcopyrightofficeCh.deBlandonnet8•CP401CH-1214Vernie,rGeneva,SwitzerlandTel.+41227490111Fax+41227490947copyright@iso.orgwww.iso.orgi©ISO2017–Allrightsreserved ISO20484:2017(E)ContentsPageForeword.....ivIntroduction.....v1Scope.....12Normativereferences....13Termsanddefinitions....13.1Atomic/molecularstructure...13.2Pressureandvacuum....13.3Gas-solidinteraction....14Termsrelatingtogas....24.1Propertiesofgases....24.2Flowofgas....25Termsrelatingtotesttechniques...45.1Testtechniques....45.2Testequipment....55.3Testequipmentcomponents...66Termsrelatingtotestprocedure....76.1Preparation/calibration....76.2Testtechniques....86.3Perofrmancelimits....8©ISO2017–Alrightsreservedi ISO20484:2017(E)ForewordISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISOmemberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnicalcommittees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhastherighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnon-governmental,inliaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnicalCommission(IEC)onallmattersofelectrotechnicalstandardization.TheproceduresusedtodevelopthisdocumentandthoseintendedforitsfurthermaintenancearedescribedintheISO/IECDirectives,Part1.InparticularthediferentapprovalcriterianeededforthediferenttypesofISOdocumentsshouldbenoted.ThisdocumentwasdraftedinaccordancewiththeeditorialrulesoftheISO/IECDirectives,Part2(seewww.iso.org/directives).Attentionisdrawntothepossibilitythatsomeoftheelementsofthisdocumentmaybethesubjectofpatentrights.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.DetailsofanypatentrightsidentifiedduringthedevelopmentofthedocumentwillbeintheIntroductionand/orontheISOlistofpatentdeclarationsreceived(seewww.iso.org/patents).Anytradenameusedinthisdocumentisinformationgivenfortheconvenienceofusersanddoesnotconstituteanendorsement.Foranexplanationonthevoluntarynatureofstandards,themeaningofISOspecifictermsandexpressionsrelatedtoconformityassessment,aswellasinformationaboutISO’sadherencetotheWorldTradeOrganization(WTO)principlesintheTechnicalBarrierstoTrade(TBT)seethefollowingURL:www.iso.org/iso/foreword.htmlISO20484waspreparedbytheEuropeanCommitteeStandardization(CEN)TechnicalCommitteeCEN/TC138,Leaktesting,incollaborationwithISOTechnicalCommitteeTC135,Non-destructivetesting,SubcommitteeSC6,Leaktesting,inaccordancewiththeagreementontechnicalcooperationbetweenISOandCEN(ViennaAgreement).ThisdocumentisbasedonandreplacestheEuropeanstandardEN1330-8:1998,Non-destructivetesting—eTrminology—Part8:eTrmsusedinleaktightnesstesting.iv©ISO2017–Allrightsreserved ISO20484:2017(E)IntroductionTheseriesofEuropeanstandards,EN1330,comprises10partspreparedseparatelybygroupsofexperts,eachgroupconsistingofexpertsinagivenNDT(non-destructivetesting)method(forEN1330-3toEN1330-10).Acomparativeexaminationofthesepartshasshowntheexistenceofcommontermsthatareoftendefineddiferently.ThesetermshavebeentakenfromEN1330-3toEN1330-10andthensplitintotwocategories:—generaltermscorrespondingtootherfieldssuchasphysics,electricity,metrology,etc.andalreadydefinedininternationaldocuments;thesetermsarethesubjectofEN1330-1;—commontermsspecifictoNDT;theseterms,thedefinitionsofwhichhavebeenharmonizedinanAdHocgroup,arethesubjectofEN1330-2.Inviewofthenatureoftheapproachtaken,thelistoftermsinEN1330-1andEN1330-2areinnowayexhaustive.EN1330consistsofthefollowingparts:—Part1:Generalterms—Part2:eTrmscommontothenon-destructivetestingmethods—Part3:eTrmsusedinindustrialradiographictesting—Part4:eTrmsusedinultrasonictesting—Part7:eTrmsusedinmagneticparticletesting—Part9:eTrmsusedinacousticemission—Part10:eTrmsusedinvisualexaminationNOTE1ISO12718replacedEN1330–5.NOTE2ISO12706waspublishedformerlyasthedraftEuropeanstandardprEN1330–6.©ISO2017–Alrightsreservedv INTERNATIONALSTANDARDISO20484:2017(E)Non-destructivetesting—Leaktesting—Vocabulary1ScopeThisdocumentdefinesthetermsusedinleaktesting.2NormativereferencesTherearenonormativereferencesinthisdocument.3TermsanddefinitionsForthepurposesofthisdocument,thefollowingtermsanddefinitionsapply.ISOandIECmaintainterminologicaldatabasesforuseinstandardizationatthefollowingaddresses:—ISOOnlinebrowsingplatform:availableathttp:/www.iso.org/obp—IECElectropedia:availableathttp:/www.electropedia.org/3.1Atomic/molecularstructure3.1.1concentrationcratioofthenumberofatomsormoleculesofagivenconstituentinagasmixturetothetotalnumberofatomsormoleculesinthemixtureNote1toentry:Foridealgases,thisisequivalenttotheratioofthepartialpressuretothetotalpressure.Note2toentry:Inothercases,theconcentrationisconsideredasmolefractionandthesymbolusedisn.B3.1.2ionizationpotentialminimumenergy,expressedinelectronvolts,requiredtoremoveanelectronfromanatomormoleculeoriontoformapositiveion3.2Pressureandvacuum3.2.1atmosphericpressurepressureoftheatmosphereataspecifiedplaceandtime3.2.2partialpressurep,pABpressurethatwouldbeexertedbyagasorvapourifitalonewaspresentinanenclosure3.3Gas-solidinteraction3.3.1getteringremovalofagasbypermanentbindinginoronasolid,usuallyinvolvingchemicalreaction©ISO2017–Alrightsreserved1 ISO20484:2017(E)3.3.2occlusionofgastrappingofundissolvedgasinasolidduringsolidification3.3.3permeationmechanismofadsorption/solution/difusion/desorptioninasolidmaterialthatallowsasubstancetopassthroughunderapartialpressurediference3.3.4permeabilitycoefficientPpermcoefficient,dependentontemperature,characterizingtheconductance(4.2.1)ofamaterialforthepermeation(3.3.3)ofagivensubstance4Termsrelatingtogas4.1Propertiesofgases4.1.1idealgasperfectgasgasobeyingtherelationshippV=nRT,wheren=m/Mwherepisthepressure;Visthevolume;misthemassofthegas;Misthemolecularmass;Ristheidealgasconstant;Tistheabsolutetemperature.4.2Flowofgas4.2.1conductanceCthroughputdividedbythediferenceinmeanpressuresprevailingattwospecifiedcross-sectionsorateithersidesoftheductororifice,assumingisothermalconditionsNote1toentry:Appliestofluidflowinaduct,orpartofaduct,oraconstriction.4.2.2flowrateq,q,qMNνrateatwhichanamountofmass,anumberofparticlesormolespassthroughagivencrosssectionofthesystemNote1toentry:Mass:q,Particles:q,Molar:q.MNνNote2toentry:Forgases,thevolumeflowrate(Volume:symbolq)isameasureofquantityonlyatspecifiedvconditions.2©ISO2017–Allrightsreserved ISO20484:2017(E)4.2.3pV-throughputqGrateatwhichavolumeofgasatspecifiedpressurepassesagivencrosssectionofthesystemNote1toentry:Inleakdetection,pV-throughputisusedtoexpresstheflowrateofgas.Thetemperatureandmolarweightordensityaregivenadditionallysothattheflowratecanbecalculatedusingthegasequation.4.2.4resistancetoflowwreciprocalofconductance(flow)4.2.5dynamicviscositycoefficientηcoefficient,dependentontemperature,thatdefinestheresistanceofaspecifiedfluidtothemotion,duetothemolecularinteractions4.3Gasleakage4.3.1leakhole,porosity,permeableelementorotherstructureinthewallofanobjectallowinggastopassfromonesideofthewalltotheotherbytheefectofpressure-orconcentration-diferenceacrossthewall4.3.2conductanceleakleakwhichconsistsofoneormorediscretepassages,includingporousareas,throughwhichafluidmayflow4.3.3orificeleakconductanceleak(4.3.2)havingadiametermuchgreaterthantheleakagepathlengthNote1toentry:Itmayalsobeconsideredasanopeninginaverythinwall.4.3.4capillaryleakconductanceleak(4.3.2)inwhichthediameterissmallcomparedtothelength4.3.5leakageratepV-throughputofaspecificfluidwhichpassesthroughaleakunderspecificconditions4.3.6leaktightobjectobjectwithaleakageratelowerthanthatstatedinaspecification4.3.7molecularleakleakofsuchgeometricconfigurationandundersuchpressureconditionsthatgasflowingthroughitobeysthelawsofmolecularflow©ISO2017–Alrightsreserved3 ISO20484:2017(E)4.3.8standardleakagerateleakagerateofaleakwithstatedstandardtemperatureandpressureatoneendand,attheotherend,apressurelowenoughtohaveanegligibleefectontheleakagerateNote1toentry:Diferentstandardpressure-andtemperatureconditionsareused[e.g.standardtemperatureandpressure(STP),standardambienttemperatureandpressure(SATP)].4.3.9permeationleakleakwhichpermitsagastoflowthroughanon-porouswall4.3.10totalleakagerateintegralleakageratesumofallleakageratesfromallleaksofanobject,expressedasapV-throughput4.3.11virtualleakapparent(notreal)leak,causedbymechanismsgeneratingasignalequivalenttoaleakageratesignalNote1toentry:Suchmechanismscanbedueto,forexample,temperatureandvolumeefectsorslowreleaseofsorbedoroccludedgasesfromsurfacesorfromthebulkofthematerial.4.3.12viscousleakleakofsuchgeometricconfigurationandundersuchpressureconditionsthatgasflowingthroughitobeysthelawsofviscousflow5Termsrelatingtotesttechniques5.1Testtechniques5.1.1accumulationtestleakagetestwhereatracergasiscollectedinaknownvolumeoveraspecifiedperiodoftimeandthepartialpressure(3.2.2)increaseofthetracergasismeasuredNote1toentry:Theleakageratecanbeobtainedbycalibratingthepartialpressurerisewiththatduetoaknownleakorcomparingthemeasuredconcentration(3.1.1)withaknownconcentration.5.1.2carriergastestflushingtestleakagetestinwhichaviscousgasflowiscreatedalongtheoutersurfaceofthetestobjectinachambertocarryescapingtracergastothesensor5.1.3vacuumtracergastestleakagetestinwhichtracergasisdetectedinaspacewherethetracergasatomsmovefreelytothesensorNote1toentry:Eachtracergasspeciesmoveswithitsspecificthermalvelocity.5.1.4bombingtestback-pressurisingtestleakagetestinwhichsealedobjectsaresubjectedtopressurizationwithtracergaspriortotestingtheminavacuumchamber4©ISO2017–Allrightsreserved ISO20484:2017(E)5.1.5bubbletestleakagetestusedtodetectleaksbytheimmersionoftheobjectinatestfluidorcoveringitsoutersurfacewithasurfactant(foaming)solutionNote1toentry:Thepressurediferenceacrossthewallsoftheobjectishighenoughthatleaksareshownbybubbleformation.5.1.6hoodtestover-allleakagetestinwhichtheobjectisplacedinasoftenclosureatatmosphericpressure(3.2.1)Note1toentry:Iftheobjectisevacuated,theenclosureisfilledwithtracergasandtheleakdetectorisconnectedtotheinnervolumeoftheobject.Note2toentry:Iftheobjectispressurizedwiththetracergas,thetestisperformedwiththesamplingprobeinsertedinthehood.5.1.7pressurechangetestleakagetestinwhichtherateofthetotalpressurechange(decayorrise)inanobjectismeasuredoveraperiodoftime5.1.8flowmeasurementtestleakagetestinwhichtheflowismeasurednecessarytomaintainapressurediferenceacrosstheobjectboundaryNote1toentry:Theupstreampressuremaybecontrolledbypressureregulatororanauxiliaryvolume.5.1.9pressuredyetestleakagetestinwhichaliquidcontainingadyeorfluorescentoilisdrivenbyapressurediferentialintotheleakinthewalloftheobjecttobetestedandisthendetectedbyavisualinspectionontheotherside5.1.10chemicalreactiontestleakagetestinwhichtheoutsideofthetestobjectisprobedwithareactivesubstanceshowingareactionwhenincontactwithescapingfluidNote1toentry:Atypicalexampleforthereactionmayinvolvethecolourchangeofanindicator.5.1.11radionuclideleakagetestleakagetestwhichusesaradioactivetracerfluidandadetectorformeasuringtheradiationemittedbythetracerfluid5.2Testequipment5.2.1tracergasleakdetectorinstrumentcapableofdetectingandmeasuringpV-throughputs(4.2.3)ofaspecifictracergaswithacceptableresponsetimeNote1toentry:Agassensoristooslowandaflowmeterisnotsensitiveenoughtobeatracergasleakdetector.5.2.2counterflowheliumleakdetectormassspectrometerleakdetectorinwhichthetracergas(heliumorhydrogen)entersthroughthebackinglineintotheoutletportofthehighvacuumpumpandthepartialpressureofthetracergasismeasuredonthehighvacuumsideofthispump©ISO2017–Alrightsreserved5 ISO20484:2017(E)5.2.3directflowleakdetectormassspectrometerleakdetectorinwhichthetracergasentersthehighvacuumsideofthepumpsystemwherethepartialpressureoftracergasismeasured5.2.4diferentialPiranigaugeleakdetector,inwhichthegascomingfromthetestobjectorasamplingprobeentersoneoftwosimilarPiranitubes(thermalconductivitygauges)beingarmsinaWheatstonebridge5.2.5dischargetubeleakindicatorglasstube,linkedtothevacuumsystemtobetested,inwhichthegaspresentinthesystemisexposedtoahighfrequencyelectricaldischargeNote1toentry:Shapeandcoloursofthedischargearerelatedtothenatureandpressureofthegaspresentinthesystem.5.2.6halogenleakdetectorleakdetectorthatissensitivetohalogentracergasNote1toentry:Examplesarealkali-iondiode-,infrared-,flame-ionization-andelectron-capturedetector.5.2.7heliumleakdetector4leakdetectorthatissensitivetohelium(He)tracergas5.2.8massspectrometerleakdetectorMSLDleakdetectorinwhichthesensingelementisamassspectrometer,tunedtorespondonlytothetracergas5.2.9sparkcoilleaktesterhighfrequencydischargecoiloftheTeslatypewhichindicatespinholesinaglassvacuumsystembyasparkjumpingbetweenthecoreofthecoilandthepinhole5.2.10ultrasonicleaktestersensorthatdetectsultrasonicsoundproducedbytheflowofagasorliquidthroughaconductanceleak(4.3.2)andwhichconvertsthistoausablesignal5.3Testequipmentcomponents5.3.1samplingprobedeviceusedtocollecttracergasfromanareaofthetestobjectandtransferittotheleakdetectoratthereducedpressurerequired5.3.2spraygundevicefordirectingafinejetoftracergasonanobjectundervacuumtesting5.3.3testsealtemporarysealonlyusedforthetest,e.g.plugsorgaskets,otherthanoperatingseals6©ISO2017–Allrightsreserved ISO20484:2017(E)5.3.4tightchambertightenclosurethatcancompletelycontaintheobjecttobetestedandthatcanbepressurizedorevacuatedtocreateapressurediferentialacrosstheobjectwall5.3.5tracerfluidfluid(gas,liquid)whichcanbedetectedbyaspecificdetectorandthusdisclosesthepresenceofaleak5.3.6vacuumboxcontainer,openatoneside,whichcanbetightlyfittedtothewalltobetestedandusedasalocalvacuumchamberforpartialtestsNote1toentry:Fortheperformanceofabubbletest,thecontainerwallsaretransparent.6Termsrelatingtotestprocedure6.1Preparation/calibration6.1.1calibratedleakleakdevicewhichprovidesaknownmassrateofflowforaspecificgasunderspecificconditions,traceabletonationalmetrologicalstandards6.1.2referenceleakcalibratedleak(6.1.1)intendedtobeusedasareferenceforthecalibrationofotherleakdevicesbycomparison6.1.3adjustmentofleakdetectorsetofoperationscarriedoutonaleakdetectorsothatitprovidesprescribedindicationscorrespondingtogivenvaluesofaleakageratetobemeasured6.1.4operatingconditionsspecifiedvalues(underreferenceconditions)dependentonthesystemandonthegasesinvolved,whichshallbemaintainedinthesystemtoperformthetestwithagiveninstrument6.1.5pump-downtimetimerequiredtoreducethepressureinasystemfromatmosphericpressure(3.2.1)tothedesiredvalue6.1.6responsefactorrelativesensitivityofaleakdetectorforagivengas,comparedtoareferencegas6.1.7responsetimetimefromthebeginningofapplicationoftracergasuntilthesignalreaches90%oftheequilibriumsignal,obtainedwhenthetracergasiscontinuouslyappliedNote1toentry:Exponentialsignalscanbedescribedbyatimeconstant(seeISO3530).6.1.8testconditionsactualconditionsofambienttemperatureandpressureunderwhichtheleakagetestisperformed©ISO2017–Alrightsreserved7 ISO20484:2017(E)6.1.9zeroadjustmentadjustmentofthezerocontrolsothattheoutputindicationoftheleakdetectorisatthezerooftheindicatingscaleoratsomeotherreferencepoint6.2Testtechniques6.2.1backing-lineporttechniquemethodoftestinginwhichtheleakdetectorisconnectedtoaportinthebacking,lineofthesystemundertest6.2.2bombingactionofsubjectingsealedtestobjectstoahighpressureoftestgas(usuallyhelium)6.2.3dynamicleakageratemeasurementleakagetestwheretheleakagerateisdeterminedbymeasuringtheequilibrium(steady-state)partialpressure(3.2.2)ofthetracergaswhilethesystemisbeingpumped6.2.4isolatedpressuretestpressuretestwheretheobjectisisolatedfromthepumpingorpressurizingsystemsothatthepressurechangesinthetestobjectifaleakexists6.2.5maskingcoveringofpartofatestobjecttopreventtracergasenteringleaksthatmayexistinthatpart6.2.6sniffingtestleakagetestinwhichtheobjectundertestispressurizedwithtracergasandtheescapingtracergasthroughleaksisdetectedbyasampling(snifer)probe6.2.7vacuumtesttestusedtodetectleakagefromanevacuatedobjectconnectedtoamassspectrometerleakdetectorbyplacingitinatightchamberfilledorpressurizedwithtracergas6.3Performancelimits6.3.1cleanuptimetime,fromtheendofapplicationoftracergas,untilthesignalfallsto10%oftheequilibriumsignal,obtainedwhenthetracergaswascontinuouslyappliedNote1toentry:Exponentialsignalscanbedescribedbyatimeconstant(seeISO3530).6.3.2detectionlimitofleakagetestsmallestleakageratethatcanberepeatablydetectedunderspecifiedconditions6.3.3instrumentsignaldriftgradualchangeofaninstrumentoutputsignalduetochangesintheambientconditionsorintheelectronics8©ISO2017–Allrightsreserved ISO20484:2017(E)6.3.4tracergasdriftgradualchangeoftheoutputsignaloftheleakdetector,duetochangesintracergaspartialpressureatthesensor6.3.5minimumdetectableleakageratesmallestleakageratethatcanbedetectedunambiguouslybyaleakdetectionsystemundertestconditions6.3.6minimumdetectablesignaloutputsignal,duetotheincomingtracergaswhichisequaltothesumofthenoiseandthedriftperspecifiedtimeofthesignalNote1toentry:Theminimumdetectablesignalisgiveninunitsoftheinstrumentoutput,e.g.scaledivisions,voltage.6.3.7backgroundsignaltotalspuriousindicationgivenbytheleakdetectionsystematthestartingpointofthetest(withoutinjectingtracergas)©ISO2017–Alrightsreserved9 ISO20484:2017(E)ICS01.040.19;19.100PriceCodeA©ISO2017–Allrightsreserved