【英文标准名称】:StandardPracticesforSimulatedServiceTestingforCorrosionofMetallicContainmentMaterialsforUseWithHeat-TransferFluidsinSolarHeatingandCoolingSystems
【原文标准名称】:太阳能加热和制冷系统中用传热液体的金属容器材料的腐蚀模拟维护试验的标准实施规程
【标准号】:ASTME745-1980(2009)
【标准状态】:现行
【国别】:美国
【发布日期】:1980
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E44.05
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:
【英文主题词】:corrosion;fieldexposure;heattransferfluids;immersionmetalliccontainmentmaterials;solarheatingandcooling;Containmentsystems/applications;Corrosion--metals/alloys;Corrosion--solardevices;Fieldtesting--solarmaterials;Heattransfer
【摘要】:Atthistimenoneofthesepracticeshavebeendemonstratedtocorrelatewithfieldservice.Becausetheseproceduresdonotrestricttheselectionofeitherthecontainmentmaterialorthefluidfortesting,itisessentialthatconsiderationbegiventotheappropriatepairingofmetalandfluid.Likewise,knowledgeofthecorrosionprotectionmechanismandtheprobablemodeoffailureofaparticularmetalishelpfulintheselectionoftestconditionsandtheobservation,interpretation,andreportingoftestresults.Itisimportantthatconsiderationbegiventoeachofthepermittedvariablesintestproceduresothattheresultswillbemeaningfullyrelatedtofieldperformance.Itisespeciallyimportantthatthetimeoftestingselectedbeadequatetocorrectlymeasuretherateofcorrosionofthecontainmentmaterial.Note18212;Corrosion,whethergeneralorlocalized,isatime-dependentphenomenon.Thistimedependencecanshowsubstantialnonlinearity.Forexample,formationofaprotectiveoxidewilldiminishcorrosionwithtime,whilecertainformsoflocalizedattackacceleratecorrosionwithtime.Theminimumtimerequiredforatesttoprovideacorrosionratethatcanbeextrapolatedforthepredictionoflong-termperformancevarieswidely,dependingontheselectionofmetalandfluid,andontheformofcorrosionattack.Therefore,itisnotpossibletoestablishasingleminimumlengthoftestapplicabletoallmaterialsandconditions.However,itisrecommendedthatforthetestsdescribedinthesepractices,atestperiodofnolessthan6monthsbeused.Furthermore,itisrecommendedthattheeffectoftimeoftestingbeevaluatedtodetectanysignificanttimedependenceofcorrosionattack.Itisessentialforthemeaningfulapplicationoftheseproceduresthatthelengthoftestbeadequatetodetectchangesinthenatureofthefluidthatmightsignificantlyalterthecorrosivityofthefluid.Forexample,exhaustionofchemicalinhibitororchemicalbreakdownofthefluidmayoccurafterperiodsofmonthsinselectedcyclesofoperation.Note28212;Manyfluidsthatmaybeconsideredforsolarapplicationscontainadditivestominimizethecorrosivityofthefluid.Manysuchadditivesareusefulonlywithinaspecificconcentrationrange,andsomeadditivesmayactuallyacceleratecorrosioniftheconcentrationfallsbelowacriticallevel.Depletionkineticscanbeastrongfunctionoftheexposedmetalsurfacearea.Therefore,fortestsinvolvingfluidswithsuchadditives,considerationmustbegiventotheratioofmetalsurfaceareatofluidvolumeasitmayrelatetoanoperatingsystem.1.1Thesepracticescovertestproceduressimulatingfieldserviceforevaluatingtheperformanceundercorrosiveconditionsofmetalliccontainmentmaterialsinsolarheatingandcoolingsystems.Alltestresultsrelatetotheperformanceofthemetalliccontainmentmaterialonlyasapartofametal/fluidpair.Performanceinthesetestprocedures,takenbyitself,doesnotnecessarilyconstituteanadequatebasisforacceptanceorrejectionofaparticularmetal/fluidpairinsolarheatingandcoolingsystems,eitheringeneralorinaparticulardesign.1.2Thesepracticesdescribetestproceduresusedtoevaluatetheresistancetodeteriorationofmetalliccontainmentmaterialsintheseveralconditionsthatmayoccurinoperationofsolarheatingandcoolingsystems.Theseconditionsinclude:(1)operatingfullflow;(2)stagnantemptyvented;(3)stagnant,closedtoatmosphere,non-draindown;and(4)stagnant,closedtoatmosphere,draindown.