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1、·Biotechnology/PharmaceuticalFacilitiesDesignApril30,2001STAINLESSSTEELTUBINGINTHEBIOTECHNOLOGYINDUSTRYByMichelleM.GonzalezThisarticledescribesingeneralterms,stainlesssteeltypesandtheirchemistry,tubing/pipingfabricationstandards,andfabricationprocedures.Italsoaddressescompliancewithbiot
2、echnologyandpharmaceuticalstandards,codes,andguides,aswellassurfacecharacterization,electropolishing,joiningtechniques,passivation,measurementandinspectionforCr/Feratios,corrosiontypes,andguidelinesforhygienicsystems.—INTRODUCTION—Chemicalservicesofanykindmayrequirespecialalloysforcorro
3、sionresistance,freedomfrommetalioncontamination,orboth.Bioprocessingapplicationscanhaveevenmorestringentrequirements,duetothehighdegreeofcleanlinessrequiredtoconveysterileandnon-sterileproductsorsolutions.Tubingand/orpipingsystems,must,thereforemeettheserequirementsintheirfabrication,pa
4、rticularlywhenitappliestotheirproductorsolutioncontactsurfaces.Stainlesssteelsareuniquelyqualifiednotonlybecauseoftheirlongservicelife,availabilityandfabricability,butalsobecausetheyarenon-corroding,non-contaminant,theycanbepolishedtoverysmoothfinishes,theyarestrongandrigid,theycanwiths
5、tandheatandchemicalsterilizationtreatments,andtheyareeasilywelded.—STAINLESSSTEELTYPES—Therearemorethan70standardtypesofstainlesssteelandmanyspecialalloys.Thesesteelsareproducedinthewroughtform(AISI-AmericanIronandSteelInstitute-types)andascastalloys(ACI-AlloyCastingInstitute-types).Gen
6、erally,allareironbased,with12%to30%chromium,0%to22%nickel,andminoramountsofcarbon,columbium,copper,molybdenum,selenium,tantalum,andtitanium.Followingaredescriptionsofthemostwidelyusedstainlesssteelsinthechemicalprocessingindustry(CPI):Wroughtstainlesssteels:Martensitic:characteristicall
7、ymagneticandhardenablebyheattreatmentareoxidationresistant.Type410beingthemostnotableexample.Thesealloyscontain12%to20%chromiumwithcontrolledamountofcarbonandotheradditives.Theircorrosionresistanceisinferiortothatofausteniticstainlesssteels,andaregenerallyusedinmildlycorrosivee
