寶潔日化培訓課件3-8-011 Passivation-Pickling Do-Don't rv 9-16-2011

Author:DennisMcCulloughCleanDesignPrinciples‘Do/Don’ts’forPassivation&PicklingMicro/CleanDesignDo-Don’tsareprimarilyreferencetrainingmaterials;forP&Gprojectexecution,alwaysrefertotheCleanDesignStandards.Micro/CleanDesignPrinciplesPassivation&Pickling:Whatarethey?Passivation:Thechangingofachemicallyactivesurfaceofametaltoamuchlessreactivestate.Alessreactivemetalwillbemorecorrosionresistant.Pickling:TheremovalofsurfaceoxidesbychemicalorelectrochemicalmeansPassivationandPicklingresultinalessreactivemetalwillbemorecorrosionresistant.PassivationandPicklingaredependentonacidtypeused,acidconcentration,time,flowandtemperature.ContactCETLmaterialexpertstovalidateaproceduretouse(seewebsite)Micro/CleanDesignPrinciplesBychemicallytreatingthesurfaceofthestainlesssteel,suchthatironisremoved,theratioofchrometoironisincreased.With“good”passivationprocedures,chrometoironratiosof0.75to2.0canbeattained.Reducingironcontentatthesurface,resultsina“chromiumrich”surfacewhichislesslikelytoformcorrosionproducts.300seriesStainlesssteelsconsistofabout70%ironalloyedwithchromium,nickelandsometimesmolybdenum.Thesealloysgettheircorrosionresistancefromtheformationofathinchromiumoxide(Cr2O3)whenoxygenispresent.Thethicknessanduniformityofthechromiumoxidelayerisrelatedtotheratioofchromiumtoirononthesurface.Passivationusesacid/acidmixestoimprovethethicknessandtheuniformityofthischromiumoxidelayer.Itdoesthisbyattackingandremovingtheirononthesurface,leavingthechromiumbehind.Thisactionincreasesthechromiumtoironratioonthesurface,thusimprovingthecorrosionresistantlayerPassivation&Pickling:Whatarethey?CleaningremovescontaminationthatwouldpreventthepassivationacidfromreachingthesurfacePassivationimprovesthepassivelayerCleaningandPassivationtogetherensureidealcorrosionresistancePassivation/Pickling:Whatarethey?Passivation:Stainlesssteelgetscorrosionresistancefromtheformationofalayerofchromiumoxide(Cr2O3).Passivationusesanacid(suchasNitricorCitric)mixestoimprovethethicknessandtheuniformityofthischromiumoxidelayeraswellasremoveanyfreeironremainingfromfabrication.Pickling:Picklingusesmuchstrongeracids(ie.,NitricHydrofluoric)andremovestheoldchromeoxidelayeraswellasembeddedironparticles,heavyscales,corrosiondepositsandweldingheattint.Italsoallowsanewsurfaceandchromiumoxidelayertobeformed.Thechromiumtoironratioisincreasedwithpickling.Micro/CleanDesignPrinciplesThedifferencebetweenpassivationandpicklingisthenatureoftheacidusedfortheprocedureandtheresultingimpactthattheacidsolutionhasontheStainlessSteelsurface.Passivationisintendedtoremoveonlylimitedamountsofbasemetalandestablisharesistantoxidelayertopreventfurtherattack.Picklingremovesmorebasemetalsandestablishesanewresistantoxidelayertopreventfurtherattack.MINIMALRISK(=standardfornewequipment)MODERATERISKHIGHRISKSS316LSS316LowergradeSSMinimumRa0.8μm(32μinch).

Ra0.8-1.0μm(32-42μinch)MuchhigherRaInternalweldsandfinishessmoothwithnovisibleroughness,pitting,corrosionordamagedareas.InternalweldsgroundsmoothInternalweldsnotcleanedortreatedCheckyourMOCcompatibilitywithyourproduct&sanitizingagentwithCETL!Micro/CleanDesignPrinciplesPassivation:MaterialsofConstructionAdditionalinformationcanbefoundonPipingConstructionSpecificationPCP-160Moredetails:SeeP&GCleanDesignStandardsoncGMPsitePassivationExecutionthroughexposuretooxidizingacidbaths.Generallyremovessmallparticlesofironoxidesbutnotlargerembeddedmaterialsizes.Piping,tanks,etc.toolargetoimmerseisbestpassivatedbycirculatinganacidsolutionthroughthepipeorvessel.Recommendtouse3rdpartypassivationexecutionsonnon-immersedvessels.Passivationusesanacid(suchasNitricorCitric)mixestoimprovethethicknessandtheuniformityofthischromiumoxidelayeraswellasremoveanyfreeironremainingfromfabrication.PicklingMosteffectiveinremovingembeddedironandoxidematerialsthroughmixtureofnitric/hydrofluoricacid.ElectropolishingElectro-chemicalprocessforsmoothingstainlesssteelsurfaces.Provideshighlusterfinish.'Best'processforobtaininglowestRavaluesonmaterials.Micro/CleanDesignPrinciplesPassivationvs.Pickling(orothercleaningmethods)FabricationdebrisSystemcontaminationWeldingdamageSystemmodification/newinstallationPassivationisarequiredprocesswhenequipmentischangedormodifiedNewequipmentmustbepassivatedpriortoproductionPreventivemaintenanceThepassivelayerisconstantlyunderattackfromcorrosiveenvironments(e.g.,purifiedwaterandcleansteamsystems)Oxidizersusedinsanitizationcleaningenablefreeironmigrationatthesurfacelayer,ifthereisasourceoffreeironRougedepositsMicro/CleanDesignPrinciplesReasonstoPassivatePassivation:Passivationcanremove“rustable”ironandothercontaminantsfromthesurfacetoprovidea“chromium-rich”surfacelayer.Thisprocessmakesironlessavailableatthesurfacetoformironoxides(rustorrouge)duringoperations.Manyacidmixcombinationcanremoveexistingrougeintanks,vesselsandpiping.Specificpassivationproceduresshouldbetestedaspicklingmayberequired.Micro/CleanDesignPrinciplesRouge“Don’t”Passivation:Canitremoverouge?NormalStainlessSteelPolishedStainlessSteelMicro/CleanDesignPrinciples“Do”“Don’t”Passivation&PicklingReducingthesurfaceroughnessreducestheopportunityforbacterialgrowthtoadheretothestainlesssteelsurface.ThisimprovementinsmoothnessfacilitateseaseinClean-in-Place(CIP)cleaning.Micro/CleanDesignPrinciples1–2;3acceptableinsomesituations4–10havehighcorrosionriskAWSD18.2ColorChartInertGasPurgeSampleNumber12345678910PPMO21025501002005001000500012,50025,000“Do”“Don’t”Loweroxygenlevelsproducecleanerweldswithlessheattint.Micro/CleanDesignPrinciples“Do”“Don’t”HeatTintRemovalWeldAreaofAusteniticStainlessSteel–LeftHalfofPictureShowsHeatTintRemovedafterPickling.RighthalfshowsunacceptableHeatTintfromimproperpurging.Micro/CleanDesignPrinciplesPassivation&Pickling“Don’t”CorrosionoftheTankforWhiteBase

1.Interfacebetweentopleveloftheliquid(whitebase)andsurfaceofthetankSS3162.Weldingjoints3.Productofcorrosion(rust)fallingtothebottomofthetank2typesofcorrosionattack:1.Pittingcorrosion–causedbyincreasingconcentrationofchloridesinwhitebase2.Crevicecorrosioncombinedwithinter-granularcorrosion–weldingjointsMicro/CleanDesignPrinciplesCorrosionofWhiteBaseTank“Don’t”CorrosionoftheTankforWhiteBase

Attackonthisvesseloccurredattheliquidvaporinterfaceaslevelroseandfell.Ifthevesselwasheatedbyanexternaljacket(steamorhotwater)orexternalelectricheatingstrips,thiswillacttoaccelerateandpromotethewet-dryexposureandthesubsequentcorrosion.Micro/CleanDesignPrinciples“Don’t”CorrosionoftheTankforWhiteBase

Thistypeoflocalized“rusting”ismostoftencausedbycrosscontaminationbycarbonsteel.Thiscanoccurwithdirectcontactwithcarbonsteel,orindirectcontactsuchasusingagrindingorpolishingwheelonthestainlesssteelthatwaspreviouslyusedoncarbonsteel.CorrosionofWhiteBaseTank“Do”“Don’t”Example:Properlycontaingrindingparticlesfromfinishedsurfaces.Micro/CleanDesignPrinciplesAlwaysusestainlesssteelgrindingdiscsandwirebrushesonstainlessapplicationsonly.Neverusecommongrindingdiscsandbrusheswithdifferentmetalapplications.Donotgrindcarbonnexttostainlessmaterialwithoutpropercontainmentorprotectingstainlessmaterial.AvoiddirectcontactwithCarbonSteel.Thisincludeswhileinstorageonpiperacks,whilemovingorhandling(suchaschainhoistorforklift)orwithinthetoolholder.RustSpotsfromGrindingParticlesFreeIronContaminationMicro/CleanDesignPrinciples“Do”“Don’t”Passivation&PicklingPicklingprovidesgoodcontroloverweldedheattintMicro/CleanDesignPrinciples“Do”“Don’t”Passivation&PicklingGoodsurfacefinishquality<0.8microns;leadstohigherqualityCIP/SIPMicro/CleanDesignPrinciples“Do”“Don’t”Poorsurfacefinishqualityandpoorweldalignment;leadstoQA/MicroriskSurfaceFinishandInternalAlignment“Do’s&Don’ts”Principles/Summary:Passivation/Picklingisarequiredprocesspriortoplacinginproductionwhenequipmentisinitiallyfabricated(new),changedormodifiedAllPSI/PSU(Pre-Startup/Post-Startup)leakchecks,hydrostaticchecks,anddrainabilitychecksmustbecompletebeforestartingpassivationprocedures.TestingtheCr(chromium)toFe(iron)ratiobeforeandafterpassivationistheonlywaytoknowifthepassivationprocedurewillbeeffective.(Note:Cr/Feratio:Chromelistedfirst,ironsecond).

Thegoalistominimizetheirononthesurfaceandmaximizethechrome.QualitypassivationcontractorswillhavethedataavailableforthepassivationproceduretheyareusingPriortopassivationtheCr/Feratiowillbeapproximately1:4.4(.228)for316LSS.

WithpassivationweaimtoincreasetheCrtoFeratioto1:1(1.0)orgreater.Passivationtimeishighlylinkedwithtemperatureandacidcontent.Thehighertemperature&acidcontent,theshorterittakestopassivate.Micro/CleanDesignPrinciplesPassivation&Pickling“Do’s&Don’ts”Principles/Summary(cont.):Passivationshouldnotbelimitedtopipingsystemsonly.Heatexchangers,tanks,andallprocessequipmentthattouchestheproductmustbepassivatedpriortouse.Thisincludespumps,/valves,andinstrumentation(e.g.,flowmeters,sensorsetc)Keeptri-clampfittingsfullyconnectedaspartofthepassivationprocessforpipingconnections.Separatepassivationsforfittingsandconnectionsarenotarequirement.Pipingconnectiongasketsandsealsforproductusecanbereplacedwithotherlowercostgasketspriortopassivationandproductusegasketsreplacedoncepassivationhasbeencompleted.Whetheroneneedstochangegasketsandsealsdependsonwhatsolutionandconditions(concentration,timeandtemperature)the

vendorisusingandthegasketmaterial.Passivationproceduresmayincludehazardouschemicalsandhightemperatures.ThepicklingandpassivationchemicalsneedtobeclearedbysiteHS&Eandariskassessmentmustbecarriedouttodeterminesafetypracticesandprocedures.Theriskassessmentshouldincludeallprocessconditionsinwhichthechemicalswillbehandled(entiresystem,smallparts,spotcleaning).Besuretofollowallsafepracticeproceduresandreviews,includinginformationcontainedwithinthechemicalMSDS’s.Micro/CleanDesignPrinciplesPassivation&Pickling“Do’s&Don’ts”Principles/Summary(cont.):Allpassivationchemicals(acid,alkali,anddetergent)andthewastematerialshavedisposalprocedures.ReviewdisposalwithsiteHS&EorEnvironmentalresources,toensurecompliance.Passivationisbestdonebyexpertsthatspecializeinthisworkandcansafelydealwiththehazardspresentduringtheprocedureandunderstandthedisposalrequirementsofresultingwastefluids.Theareaaroundapassivationoperationmustnormallyberestrictedtothoseinvolvedintheprocedu