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1、Designation:D4787?13StardPracticefContinuityVerificationofLiquidSheetLiningsAppliedtoConcreteSubstrates1ThisstardisissuedunderthefixeddesignationD4787thenumberimmediatelyfollowingthedesignationindicatestheyearofiginalado

2、ptioninthecaseofrevisiontheyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.1.Scope1.1Thispracticecoversproceduresthatmaybeused

3、toallowthedetectionofdiscontinuitiesinnonconductiveliningsothernonconductivecoatingsappliedtoconcretesubstrates.1.2Discontinuitiesmayincludepinholesinternalvoidsholidayscracksconductiveinclusions.1.3Thispracticedescribes

4、detectionofdiscontinuitiesutilizingahighvoltagesparktesterusingeitherpulsedcontinuousdcvoltage.NOTE1—FfurtherinfmationondiscontinuitytestingrefertoNACEStardSP01882006PracticeD5162.1.4Thispracticedescribesproceduresbothwi

5、thwithouttheuseofaconductiveunderlayment.1.5ThevaluesstatedinSIunitsaretoberegardedasstard.Thevaluesgiveninparenthesesarefinfmationonly.1.6Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Iti

6、stheresponsibilityoftheuserofthisstardtoestablishappropriatesafetyhealthpracticesdeterminetheapplicabilityofregulatylimitationspritouse.FaspecifichazardstatementseeSection7.2.ReferencedDocuments2.1ASTMStards:2D5162Practi

7、cefDiscontinuity(Holiday)TestingofNonconductiveProtectiveCoatingonMetallicSubstratesG62TestMethodsfHolidayDetectioninPipelineCoatings2.2NACEStards:3SP01882006Discontinuity(Holiday)TestingofProtectiveCoatings3.Terminology

8、3.1DefinitionsofTermsSpecifictoThisStard:3.1.1conductiveunderlaymentn—acontinuouslayerappliedtothepreparedconcretesurfacepritotheapplicationofanonconductivelininglayer(s)thatwillallowhighvoltagesparktestingfdiscontinuiti

9、esintheliningasitwillconductthecurrentpresentwhenthesparkisgenerated.3.1.2currentsensitivityn—somehighvoltagetestershaveadjustablecurrentsensitivitythatcanbeusedtopreventlowlevelsofcurrentflowactivatingtheaudiblealarm.Th

10、ealarmsensitivitycontrolsetsthethresholdcurrentatwhichtheaudiblealarmsounds.Ifthehighvoltagecangetheliningasmallamountofcurrentwillflowwhilethisgeisestablished.Iftheliningcontainsapigmentthatallowsalowlevelleakagecurrent

11、toflowfromtheprobewhiletestingthethresholdcurrentcanbesetsothatthealarmdoesnotsounduntilthiscurrentisexceededthatiswhenaholidayflawisdetected.Increasingthecurrentthresholdsettingmakestheinstrumentlesssensitivetothislowle

12、velcurrentflowdecreasingthecurrentthresholdsettingmakestheinstrumentmesensitivetocurrentflow.3.1.3discontinuityn—alocalizedliningsitethathasadielectricstrengthlessthanadeterminedtestvoltage.3.1.4highvoltagesparktestern—a

13、nelectricaldevice(producingavoltageinexcessof500V)usedtolocatediscontinuitiesinanonconductiveprotectivecoatingappliedtoaconductivesubstrate.Thehighvoltageisappliedtothecoatingliningusinganexplingelectrodeanycurrentresult

14、ingfromthehighvoltagepassingthroughadiscontinuityinthecoatingliningispassedtothedeviceviaasignalreturncable(alsoknownasagroundearthwire).3.1.5holidayn—smallfaultspinholesthatpermitcurrenttoflowthroughtheconductivesubstra

15、tealsoknownasadiscontinuity.1ThispracticeisunderthejurisdictionofASTMCommitteeD01onPaintRelatedCoatingsMaterialsApplicationsisthedirectresponsibilityofSubcommitteeD01.46onIndustrialProtectiveCoatings.Currenteditionapprov

16、edFeb.12013.PublishedMarch2013.iginallyapprovedin1988.Lastpreviouseditionapprovedin2008asD4787–08.DOI:10.1520D478713.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustomerServiceat.FAnnualBookofASTMStards

17、volumeinfmationrefertothestard’sDocumentSummarypageontheASTMwebsite.3AvailablefromNACEInternational(NACE)1440SouthCreekDr.HoustonTX770844906:www.nace.g.Copyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohocken

18、PA194282959.UnitedStates15.1.5Positywithintheconcrete5.1.6Abovebelowgradeelevation5.1.7Indooutdolocation5.1.8Temperaturehuity5.1.9Ageofconcrete.5.2Theelectricalconductivityofconcreteitselfmaybesuccessfullyusedfhighvoltag

19、econtinuitytestingofliningsapplieddirectlywithnospecificconductiveunderlaymentinstalled.Howeverthevoltagerequiredtofindadiscontinuitymayvarygreatlyfrompointtopointonthestructure.Thisvariancemayreducethetestreliability.5.

20、3Althoughthemostcommonconductiveunderlaymentsareliquidprimersappliedbytrowelrollerspraywhichcontaincarbongraphitefillersothersmaytakethefmofthefollowing:5.3.1Sheetappliedgraphiteveils5.3.2Conductivepolymers5.3.3Conductiv

21、egraphitefibers5.3.4Conductivemetallicfibers5.3.5Conductivemetallicscreening.5.4Liquidappliedconductiveunderlaymentsmaybedesirableastheycanservetoaddressimperfectionsintheconcretesurfaceprovideabetterbasefwhichtoapplythe

22、lining.5.5Thispracticeisintendedfuseonlywithnewliningsappliedtoconcretesubstrates.Inspectingaliningpreviouslyexposedtoanimmersionconditioncouldresultindamagingtheliningproduceanerroneousdetectionofdiscontinuitiesduetoper

23、meationmoistureabsptionofthelining.Depositsmayalsobepresentonthesurfacecausingtelegraphing.Theuseofahighvoltagetesteronapreviouslyexposedliningisnotrecommendedbecauseofpossiblesparkthroughwhichwilldamageanotherwisesoundl

24、ining.Alowvoltagetestercanbeusedbutcouldproduceerroneousreadings.5.6Theusermayconsiderthispracticewhenperfmancerequirementsofthelininginaspecifiedchemicalenvironmentrequireassuranceofaliningfreeofdiscontinuities.5.7Facts

25、affectingthedielectricpropertiestestvoltageshallbeconsidered.Somefactsarethecuringtimeofliquidappliedliningsthepossiblepresenceofelectricallyconductivefillerssolventsboththepossiblepresenceofairinclusionsvoidsthecompatib

26、ilityofconductiveunderlaymentswiththespecifiedlining.5.8Apulseddchighvoltagemaycausealiningtobreakdownatalowervoltagethanwouldbethecasefacontinuousdcvoltage.6.Apparatus6.1HighVoltageSparkTester—Anelectricaldetectwithavol

27、tageratinginexcessof500V.Thedetectistoconsistofanelectricalenergysourceanexplingelectrodeasignalreturncableconnectionwire.Thedetectshallbeequippedwithavisualaudibleindicatboth.6.1.1ElectricalEnergySource—Eitherdcpulsatin

28、gdctypewiththeappropriatetestvoltage.6.1.2ExplingElectrode—Ametalbrushconductiverubberstripthefulllengthofwhichshallbecapableofmaintainingcontinuouscontactwiththesurfacebeinginspected.6.1.3SignalReturnCableWiretypicallys

29、tred14to16gagecopperwire.6.1.4VisualAudibleIndicatsbothtosignalaclosedelectricalcircuit.Suchsignalsshallbeessentialftestingtheunderlaymentfelectricalconductivityfexposingdiscontinuitiesintheliningafterithasbeenapplied.6.

30、1.5HighVoltagePulsatingDCSparkTester—Adeviceusedtolocatediscontinuitieswhereelectricalpulsesaregeneratingbetween2060cps.Eachpulseisonfaperiodoftimebetween20200s.6.1.6HighVoltageContinuousDCSparkTester—Adeviceusedtolocate

31、discontinuitieswherethevoltageiscontinuouslypresentonthesurfaceoftheprotectivecoating.7.Hazards7.1Solventsretainedintheappliedunderlaymentliningmaycreateanexplosiveenvironmentwiththehighvoltagetestersaswellasproduceanerr

32、oneousresult.8.ConductiveUnderlayments8.1Theconductiveunderlaymentshallnotrelyontheconcretesubstrate’selectricalproperties.8.2Thespecifiedliningshallbecompatiblewiththespecifiedconductiveunderlayment.8.3Application:8.3.1

33、Thefinishedconductiveunderlaymentsurfaceshallberelativelysmooth.Theconductiveunderlaymentshallbeconsideredpartoftheliningsystemmustbeinstalledinaccdancewiththemanufacturer’slatestpublishedinstructions.8.3.2Visuallyverify

34、thattheconductiveunderlaymentcoverstheentireareatobelined.Breaksatexpansionjointsconstructionjointsareallowableunlessotherwisespecified.8.4VerificationofUnderlaymentConductivity:8.4.1Thesurfaceoftheappliedconductiveunder

35、laymentshallbecleandryfreeofoilgreasedirtothercontaminantsbesufficientlycuredinaccdancewiththemanufacturer’slatestpublishedinstructionsatthetimetheconductivitytestingisperfmed.(Warning—SeeSection7.)8.4.2Verifytheoperatio

36、nofthetestinstrumentinaccdancewithSection9.8.4.3AdjustthehighvoltagetestinstrumentinaccdancewithSection11.8.4.4Connectthetestinstrumenttotheinstalledunderlaymentotherappropriategroundusingthesignalreturncable.Ifelectrica

37、lisolationacrossanexpansionjointisencounteredthesignalreturncablemustbemovedtoanappropriategroundinthesamesectionbeingtested.8.4.5Placetheexplingelectrodeonanonconductivespacersothatanairgapbetweenthesurfaceoftheunderlay

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