ASTM B117-2016

Designation:B117−16StandardPracticeforOperatingSaltSpray(Fog)Apparatus1ThisstandardisissuedunderthefixeddesignationB117;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thispracticecoverstheapparatus,procedure,andconditionsrequiredtocreateandmaintainthesaltspray(fog)testenvironment.SuitableapparatuswhichmaybeusedisdescribedinAppendixX1.1.2Thispracticedoesnotprescribethetypeoftestspeci-menorexposureperiodstobeusedforaspecificproduct,northeinterpretationtobegiventotheresults.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2B368TestMethodforCopper-AcceleratedAceticAcid-SaltSpray(Fog)Testing(CASSTest)D609PracticeforPreparationofCold-RolledSteelPanelsforTestingPaint,Varnish,ConversionCoatings,andRelatedCoatingProductsD1193SpecificationforReagentWaterD1654TestMethodforEvaluationofPaintedorCoatedSpecimensSubjectedtoCorrosiveEnvironmentsE70TestMethodforpHofAqueousSolutionsWiththeGlassElectrodeE691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethodG85PracticeforModifiedSaltSpray(Fog)Testing3.SignificanceandUse3.1Thispracticeprovidesacontrolledcorrosiveenviron-mentwhichhasbeenutilizedtoproducerelativecorrosionresistanceinformationforspecimensofmetalsandcoatedmetalsexposedinagiventestchamber.3.2Predictionofperformanceinnaturalenvironmentshasseldombeencorrelatedwithsaltsprayresultswhenusedasstandalonedata.3.2.1Correlationandextrapolationofcorrosionperfor-mancebasedonexposuretothetestenvironmentprovidedbythispracticearenotalwayspredictable.3.2.2Correlationandextrapolationshouldbeconsideredonlyincaseswhereappropriatecorroboratinglong-termatmo-sphericexposureshavebeenconducted.3.3Thereproducibilityofresultsinthesaltsprayexposureishighlydependentonthetypeofspecimenstestedandtheevaluationcriteriaselected,aswellasthecontroloftheoperatingvariables.Inanytestingprogram,sufficientrepli-catesshouldbeincludedtoestablishthevariabilityoftheresults.Variabilityhasbeenobservedwhensimilarspecimensaretestedindifferentfogchamberseventhoughthetestingconditionsarenominallysimilarandwithintherangesspeci-fiedinthispractice.4.Apparatus4.1Theapparatusrequiredforsaltspray(fog)exposureconsistsofafogchamber,asaltsolutionreservoir,asupplyofsuitablyconditionedcompressedair,oneormoreatomizingnozzles,specimensupports,provisionforheatingthechamber,andnecessarymeansofcontrol.Thesizeanddetailedcon-structionoftheapparatusareoptional,providedtheconditionsobtainedmeettherequirementsofthispractice.4.2Dropsofsolutionwhichaccumulateontheceilingorcoverofthechambershallnotbepermittedtofallonthespecimensbeingexposed.4.3Dropsofsolutionwhichfallfromthespecimensshallnotbereturnedtothesolutionreservoirforrespraying.4.4Materialofconstructionshallbesuchthatitwillnotaffectthecorrosivenessofthefog.1ThispracticeisunderthejurisdictionofASTMCommitteeG01onCorrosionofMetalsandisthedirectresponsibilityofSubcommitteeG01.05onLaboratoryCorrosionTests.CurrenteditionapprovedMarch15,2016.PublishedApril2016.Originallyapprovedin1939.Lastpreviouseditionapprovedin2011asB117–11.DOI:10.1520/B0117-16.2ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959.UnitedStatesCopyrightASTMInternational--``,``,`,,````,`,,`,``,,,``,,,,-`-`,,`,,`,`,,`---4.5AllwaterusedforthispracticeshallconformtoTypeIVwaterinSpecificationD1193(exceptthatforthispracticelimitsforchloridesandsodiummaybeignored).Thisdoesnotapplytorunningtapwater.Allotherwaterwillbereferredtoasreagentgrade.NOTE1—Waterusedwithaconductivity≤1.0µS/cm(orresistivity≥1.0MΩ·cm)maycausedamagetosomeequipmentduetothereactivenatureofthewater.Inaddition,itmaycauseissueswithstabilizingpHmeasurements.5.TestSpecimens5.1Thetypeandnumberoftestspecimenstobeused,aswellasthecriteriafortheevaluationofthetestresults,shallbedefinedinthespecificationscoveringthematerialorproductbeingexposedorshallbemutuallyagreeduponbetweenthepurchaserandtheseller.6.PreparationofTestSpecimens6.1Specimensshallbesuitablycleaned.Thecleaningmethodshallbeoptionaldependingonthenatureofthesurfaceandthecontaminants.Careshallbetakenthatspecimensarenotrecontaminatedaftercleaningbyexcessiveorcarelesshandling.6.2Specimensfortheevaluationofpaintsandotherorganiccoatingsshallbepreparedinaccordancewithapplicablespecification(s)forthematerial(s)beingexposed,orasagreeduponbetweenthepurchaserandthesupplier.Otherwise,thetestspecimensshallconsistofsteelmeetingtherequirementsofPracticeD609andshallbecleanedandpreparedforcoatinginaccordancewiththeapplicableprocedureofPracticeD609.6.3Specimenscoatedwithpaintsornonmetalliccoatingsshallnotbecleanedorhandledexcessivelypriortotest.6.4Wheneveritisdesiredtodeterminethedevelopmentofcorrosionfromanabradedareainthepaintororganiccoating,ascratchorscribedlineshallbemadethroughthecoatingwithasharpinstrumentsoastoexposetheunderlyingmetalbeforetesting.TheconditionsofmakingthescratchshallbeasdefinedinTestMethodD1654,unlessotherwiseagreeduponbetweenthepurchaserandtheseller.6.5Unlessotherwisespecified,thecutedgesofplated,coated,orduplexmaterialsandareascontainingidentificationmarksorincontactwiththeracksorsupportsshallbeprotectedwithasuitablecoatingstableundertheconditionsofthepractice.NOTE2—Shoulditbedesirabletocuttestspecimensfrompartsorfrompreplated,painted,orotherwisecoatedsteelsheet,thecutedgesshallbeprotectedbycoatingthemwithpaint,wax,tape,orothereffectivemediasothatthedevelopmentofagalvaniceffectbetweensuchedgesandtheadjacentplatedorotherwisecoatedmetalsurfaces,isprevented.7.PositionofSpecimensDuringExposure7.1Thepositionofthespecimensinthesaltspraychamberduringthetestshallbesuchthatthefollowingconditionsaremet:7.1.1Unlessotherwisespecified,thespecimensshallbesupportedorsuspendedbetween15and30°fromtheverticalandpreferablyparalleltotheprincipaldirectionofflowoffogthroughthechamber,baseduponthedominantsurfacebeingtested.7.1.2Thespecimensshallnotcontacteachotheroranymetallicmaterialoranymaterialcapableofactingasawick.7.1.3Eachspecimenshallbeplacedtopermitunencum-beredexposuretothefog.7.1.4Saltsolutionfromonespecimenshallnotdriponanyotherspecimen.NOTE3—Suitablematerialsfortheconstructionorcoatingofracksandsupportsareglass,rubber,plastic,orsuitablycoatedwood.Baremetalshallnotbeused.Specimensshallpreferablybesupportedfromthebottomortheside.Slottedwoodenstripsaresuitableforthesupportofflatpanels.Suspensionfromglasshooksorwaxedstringmaybeusedaslongasthespecifiedpositionofthespecimensisobtained,ifnecessarybymeansofsecondarysupportatthebottomofthespecimens.8.SaltSolution8.1Thesaltsolutionshallbepreparedbydissolving561partsbymassofsodiumchloridein95partsofwaterconformingtoTypeIVwaterinSpecificationD1193(exceptthatforthispracticelimitsforchloridesandsodiummaybeignored).Carefulattentionshouldbegiventothechemicalcontentofthesalt.Thesaltusedshallbesodiumchloridewithnotmorethan0.3%bymassoftotalimpurities.Halides(Bromide,Fluoride,andIodide)otherthanChlorideshallconstitutelessthan0.1%bymassofthesaltcontent.Coppercontentshallbelessthan0.3ppmbymass.Sodiumchloridethathashadanti-cakingagentsaddedshallnotbeusedbecausesuchagentsmayactascorrosioninhibitors.SeeTable1foralistingoftheseimpurityrestrictions.Uponagreementbetweenthepurchaserandtheseller,analysismayberequiredandlimitsestablishedforelementsorcompoundsnotspecifiedinthechemicalcompositiongivenabove.8.2ThepHofthesaltsolutionshallbesuchthatwhenatomizedat35°C(95°F)thecollectedsolutionwillbeinthepHrangefrom6.5to7.2(Note4).Beforethesolutionisatomizeditshallbefreeofsuspendedsolids(Note5).ThepHmeasurementshallbemadeat2363°C(7365°F)usingasuitableglasspH-sensingelectrode,referenceelectrode,andpHmetersysteminaccordancewithTestMethodE70.pHmeasurementshallberecordedoncedaily(exceptonweekends,orholidayswhenthesaltspraytestisnotinter-ruptedforexposing,rearranging,orremovingtestspecimensortocheckandreplenishthesolutioninthereservoir.ThemaximumintervalbetweenpHmeasurementsshallnotexceed96h).Onlydiluted,reagentgradehydrochloricacid(HCl)orreagentgradesodiumhydroxide(NaOH)shallbeusedtoadjustthepH.NOTE4—TemperatureaffectsthepHofasaltsolutionpreparedfromwatersaturatedwithcarbondioxideatroomtemperatureandpHadjust-mentmaybemadebythefollowingthreemethods:(1)WhenthepHofasaltsolutionisadjustedatroomtemperature,andatomizedat35°C(95°F),thepHofthecollectedsolutionwillbehigherthantheoriginalsolutionduetothelossofcarbondioxideatthehighertemperature.WhenthepHofthesaltsolutionisadjustedatroomtemperature,itisthereforenecessarytoadjustitbelow6.5sothecollectedsolutionafteratomizingat35°C(95°F)willmeetthepHlimitsof6.5to7.2.Takeabouta50-mLsampleofthesaltsolutionaspreparedatroomtemperature,boilgentlyfor30s,cool,anddeterminethepH.WhentheB117−16CopyrightASTMInternational--``,``,`,,````,`,,`,``,,,``,,,,-`-`,,`,,`,`,,`---pHofthesaltsolutionisadjustedto6.5to7.2bythisprocedure,thepHoftheatomizedandcollectedsolutionat35°C(95°F)willcomewithinthisrange.(2)Heatingthesaltsolutiontoboilingandcoolingto35°C(95°F)andmaintainingitat35°C(95°F)forapproximately48hbeforeadjustingthepHproducesasolutionthepHofwhichdoesnotmateriallychangewhenatomizedat35°C(95°F).(3)Heatingthewaterfromwhichthesaltsolutionispreparedto35°C(95°F)orabove,toexpelcarbondioxide,andadjustingthepHofthesaltsolutionwithinthelimitsof6.5to7.2producesasolutionthepHofwhichdoesnotmateriallychangewhenatomizedat35°C(95°F).NOTE5—Thefreshlypreparedsaltsolutionmaybefilteredordecantedbeforeitisplacedinthereservoir,ortheendofthetubeleadingfromthesolutiontotheatomizermaybecoveredwithadoublelayerofcheeseclothtopreventpluggingofthenozzle.NOTE6—ThepHcanbeadjustedbyadditionsofdiluteACSreagentgradehydrochloricacidorsodiumhydroxidesolutions.9.AirSupply9.1ThecompressedairsupplytotheAirSaturatorTowershallbefreeofgrease,oil,anddirtbeforeusebypassingthroughwell-maintainedfilters(Note7).ThisairshouldbemaintainedatasufficientpressureatthebaseoftheAirSaturatorTowertomeetthesuggestedpressuresofTable2atthetopoftheAirSaturatorTower.NOTE7—Theairsupplymaybefreedfromoilanddirtbypassingitthroughasuitableoil/waterextractor(thatiscommerciallyavailable)tostopanyoilfromreachingtheAirSaturatorTower.Manyoil/waterextractorshaveanexpirationindicator,properpreventivemaintenanceintervalsshouldtaketheseintoaccount.9.2Thecompressedairsupplytotheatomizernozzleornozzlesshallbeconditionedbyintroducingitintothebottomofatowerfilledwithwater.Acommonmethodofintroducingtheairisthroughanairdispersiondevice(X1.4.1).Thelevelofthewatermustbemaintainedautomaticallytoensureadequatehumidification.Itiscommonpracticetomaintainthetemperatureinthistowerbetween46and49°C(114–121°F)tooffsetthecoolingeffectofexpansiontoatmosphericpressureduringtheatomizationprocess.Table2showsthetemperature,atdifferentpressures,thatarecommonlyusedtooffsetthecoolingeffectofexpansiontoatmosphericpressure.9.3Carefulattentionshouldbegiventotherelationshipoftowertemperaturetopressuresincethisrelationshipcanhaveadirectimpacttomaintainingpropercollectionrates(Note8).ItispreferabletosaturatetheairattemperatureswellabovethechambertemperatureasinsuranceofawetfogaslistedinTable2.NOTE8—Ifthetowerisrunoutsideofthesesuggestedtemperatureandpressurerangestoachievepropercollectionratesasdescribedin10.2ofthispractice,othermeansofverifyingthepropercorrosionrateinthechambershouldbeinvestigated,suchastheuseofcontrolspecimens(panelsofknownperformanceinthetestconducted).Itispreferredthatcontrolpanelsbeprovidedthatbrackettheexpectedtestspecimenperformance.Thecontrolsallowforthenormalizationoftestconditionsduringrepeatedrunningofthetestandwillalsoallowcomparisonsoftestresultsfromdifferentrepeatsofthesametest.(RefertoAppendixX3,EvaluationofCorrosiveConditions,formasslossprocedures).10.ConditionsintheSaltSprayChamber10.1Temperature—Theexposurezoneofthesaltspraychambershallbemaintainedat3562°C(9563°F).Eachsetpointanditstolerancerepresentsanoperationalcontrolpointforequilibriumconditionsatasinglelocationinthecabinetwhichmaynotnecessarilyrepresenttheuniformityofcondi-tionsthroughoutthecabinet.Thetemperaturewithintheexposurezoneoftheclosedcabinetshallberecorded(Note9)atleastoncedaily(exceptonSaturdays,Sundays,andholidayswhenthesaltspraytestisnotinterruptedforexposing,TABLE1MaximumAllowableLimitsforImpurityLevelsinSodiumChlorideA,B,CNOTE1—Ameasurablelimitforanti-cakingagentsisnotbeingdefinedasaresultofhowsaltismanufactured.Duringsaltmanufacturing,itiscommonpracticetocreatesaltslurryfromtherawsaltmined.Acrystallizationprocessthencapturesthepuresaltfromthisslurry.Somenaturallyoccurringanti-cakingagentscanbeformedinthisprocessandarenotremovedfromtheresultantproduct.Avoidsaltproductswhereextraanti-cakingagentsareadded.Additionally,whendoinganelementalanalysisofsalt,therecanbetraceelementspresentthatareeitherastand-aloneelementorpartofananti-cakingagent.Itisnoteconomicallyfeasibletoknowwheresuchelementscamefromduetothelonglistofpossibleanti-cakingagentsforwhichtherewouldhavetobetesting.Therefore,asaltproductthatmeetstheimpurity,halide,andcopperlimitswithnoanti-cakingagentsaddedwillbeacceptable.Thesaltsuppliercanprovideananalysisofthesaltwithastatementindicatingthatanti-cakingagentswerenotaddedtotheproduct.ImpurityDescriptionAllowableAmountTotalImpurities#0.3%Halides(Bromide,FluorideandIodide)excludingChloride<0.1%Copper<0.3ppmAnti-cakingAgentsNoneAddedAAcommonformulausedtocalculatetheamountofsaltrequiredbymasstoachievea5%saltsolutionofaknownmassofwateris:0.0533MassofWater5MassofNaClrequiredThemassofwateris1gper1mL.Tocalculatethemassofsaltrequiredingramstomix1Lofa5%saltsolution,multiply0.053by1000g(35.27oz,themassof1Lofwater).Thisformulayieldsaresultof53g(1.87oz)ofNaClrequiredforeachlitreofwatertoachievea5%saltsolutionbymass.The0.053multiplierforthesodiumchlorideusedaboveisderivedbythefollowing:1000g(massofafullLofwater)dividedby0.95(waterisonly95%ofthetotalmixturebymass)yields1053gThis1053gisthetotalmassofthemixtureofoneLofwaterwitha5%sodiumchlorideconcentration.1053gminustheoriginalweightoftheLofwater,1000g,yields53gfortheweightofthesodiumchloride.53goftotalsodiumchloridedividedbytheoriginal1000gofwateryieldsa0.053multiplierforthesodiumchloride.Asanexample:tomixtheequivalentof200L(52.83gal)of5%sodiumchloridesolution,mix10.6kg(23.37lb)ofsodiumchlorideinto200L(52.83gal)ofwater.200Lofwaterweighs200000g.200000gofwater×0.053(sodiumchloridemultiplier)=10600gofsodiumchloride,or10.6kg.BInordertoensurethatthepropersaltconcentrationwasachievedwhenmixingthesolution,itisrecommendedthatthesolutionbecheckedwitheitherasalimeterhydrometerorspecificgravityhydrometer.Whenusingasalimeterhydrometer,themeasurementshouldbebetween4and6%at25°C(77°F).CIfthepurityofthesaltusedis>99.9%,thenthelimitsforhalidescanbeignored.Thisisduetothefactthatthehalidescannotbe$0.1%withasaltpurityof>99.9%.Ifthesaltusedisoflowerpurity,thentestforhalides.TABLE2SuggestedTemperatureandPressureGuidelinefortheTopoftheAirSaturatorTowerfortheOperationofaTestat35°C(95°F)AirPressure,kPaTemperature,°CAirPressure,psiTemperature,°F83461211496471411711048161191244918121B117−16CopyrightASTMInternational--``,``,`,,````,`,,`,``,,,``,,,,-`-`,,`,,`,`,,`---rearranging,orremovingtestspecimensortocheckandreplenishthesolutioninthereservoir)NOTE9—Asuitablemethodtorecordthetemperatureisbyacontinu-ousrecordingdeviceorbyathermometerwhichcanbereadfromoutsidetheclosedcabinet.Therecordedtemperaturemustbeobtainedwiththesaltspraychamberclosedtoavoidafalselowreadingbecauseofwet-bulbeffectwhenthechamberisopen.10.2AtomizationandQuantityofFog—Placeatleasttwocleanfogcollectorsperatomizertowerwithintheexposurezonesothatnodropsofsolutionwillbecollectedfromthetestspecimensoranyothersource.Positionthecollectorsintheproximityofthetestspecimens,onenearesttoanynozzleandtheotherfarthestfromallnozzles.AtypicalarrangementisshowninFig.1.Thefogshallbesuchthatforeach80cm2(12.4in.2)ofhorizontalcollectingarea,therewillbecollectedfrom1.0to2.0mLofsolutionperhourbasedonanaveragerunofatleast16h(Note10).Thesodiumchlorideconcentrationofthecollectedsolutionshallbe561mass%(Notes10-12).ThepHofthecollectedsolutionshallbe6.5to7.2.ThepHmeasurementshallbemadeasdescribedin8.2(Note4).Bothsodiumchlorideconcentration(measuredasspecificgravity)andvolumeofcondensatecollected(mea-suredinmL)shallberecordedoncedaily(exceptonweekends,orholidayswhenthesaltspraytestisnotinter-ruptedforexposing,rearranging,orremovingtestspecimensortocheckandreplenishthesolutioninthereservoir.Themaximumintervalbetweenthesedatacollectionmeasurementsshallnotexceed96h).NOTE10—Suitablecollectingdevicesareglassorplasticfunnelswiththestemsinsertedthroughstoppersintograduatedcylinders,orcrystal-lizingdishes.Funnelsanddisheswithadiameterof10cm(3.94in.)haveanareaofabout80cm2(12.4in.2).NOTE11—Thespecificgravityofsaltsolutionwillchangewithtemperature.Table3showssaltconcentrationanddensityversustempera-ture3andcanbeusedtodetermineifthesamplemeasurediswithinspecification.Thesampletobemeasuredmaybeacompositesamplefrommultiplefog-collectingdeviceswithinasinglecabinet,ifnecessary,toobtainsufficientsolutionvolumeformeasurement.Table3showsthesaltconcentrationandsaltdensityof4%,5%and6%saltsolutionbetween20°Cand40°C.Ameasurementthatfallswithintherangebetween4%and6%isacceptable.Itisimportanttounderstandtheequipmentbeingusedtomeasurespecificgravity.Onecommonpracticeforspecificgravitymeasurementistheuseofahydrometer.Ifused,carefulattentiontothehydrometertypeisimportantasmostaremanufacturedandcalibratedformeasurementsat15.6°C(60°F).Sincesaltdensityistemperaturedependent,anoffsetwillbenecessarytomakeanaccuratemeasurementatothertemperatures.Contactthehydrometermanufacturertofindtheproperoffsetforthehydrometerbeingused.NOTE12—Saltsolutionsfrom2to6%willgivethesameresults,thoughforuniformitythelimitsaresetat4to6%.10.3Thenozzleornozzlesshallbesodirectedorbaffledthatnoneofthespraycanimpingedirectlyonthetestspecimens.11.ContinuityofExposure11.1Unlessotherwisespecifiedinthespecificationscover-ingthematerialorproductbeingtested,thetestshallbecontinuousforthedurationoftheentiretestperiod.Continu-ousoperationimpliesthatthechamberbeclosedandthesprayoperatingcontinuouslyexceptfortheshortdailyinterruptionsnecessarytoinspect,rearrange,orremovetestspecimens,tocheckandreplenishthesolutioninthereservoir,andtomakenecessaryrecordingsasdescribedinSection10.NOTE13—Operationsshouldbesoscheduledthatthecumulative3“ThermodynamicPropertiesoftheNaCl+H2OsystemII.ThermodynamicPropertiesofNaCl(aq),NaCl.2H2O(cr),andPhaseEquilibria,”JournalofPhysicsandChemistryReferenceData,Vol.21,No.4,1992.NOTE1—Thisfigureshowsatypicalfogcollectorarrangementforasingleatomizertowercabinet.Thesamefogcollectorarrangementisalsoapplicableformultipleatomizertowerandhorizontal(“T”type)atomizertowercabinetconstructionsaswell.FIG.1ArrangementofFogCollectorsB117−16CopyrightASTMInternational--``,``,`,,````,`,,`,``,,,``,,,,-`-`,,`,,`,`,,`---maximumtimefortheseinterruptionsareheldto60minorlessperday.Itisrecommendedtohaveonlyoneinterruptionperdayifpossible.Ifinterruptiontimeislongerthat60min,itshouldbenotedinthetestreport.12.PeriodofExposure12.1Theperiodofexposureshallbeasdesignatedbythespecificationscoveringthematerialorproductbeingtestedor