IS 2629 (1985): Recommended Practice for Hot-Dip ...

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2 > 0 B Bhart hari N ti atakam Knowledge is such a treasure which cannot be stolen Invent a New India Using Knowledge IS 2629 (1985): Recommended Practice for Hot-DipGalvanizing of iron and Steel [MTD 7: Light Metals andtheir Alloys]IS :2629-1985(Reaffirmed1994)IndianStandard RECOMMENDEDPRACTICEFORHOT-DIPGALVANIZING OF iron ANDSTEEL( FirstRevision)ThirdReprintAUGUST1997 UDC6()9.\ ~ Copyright 1986 BIfI<EA () 0 FINnI A N STANDAR[) SMANAKIHIAVAN,9 BAIIADURSHAllZAFARMARciNI~WDFLIII110002G r7 November1986 : 2629 - 1985 RECOMMENDEDPRACTICEFORHOT-DIPGALVANIZING OFIRONANDSTEEL(Pages15, 16and17,AppendixA,last column)-Substitute'Mayberejected'for'Yf' S'and'Maybeacc('pted'for'No'whereverappe aring.(SMDC28)Printedat Dee KayPrinter New Delhi. India A1\JENDJ\ 1995 TOIS2629:1985nECOMMENDEDPR~CTICEFORHOT DIP GALVANIZING OF iron AND STEEL(PaR('3.(101/\(' \{<c-uvnc(')--SubvntutcthefollowlllglorI hel',,,lmg.))))]}

3 L'hcg!av,llIl/llIgproll'"''L\II11('gfOUp l'lJlogetherunderthreecalr!:!one-"na mclv(it)we:pron''''',(h) (c)acombmauon01dryandweipro,e""bvcouuuuo u-,or h!:!,l!v,lm/lll1!: (POIiC9.(/011\1' )-Aut!thefollowlllgdllhl'cudof1'I,llI"C. ' \ ,J" ,..".., ,IIIdro"''''1II!:!.'(Pa)!,c11,111/I1It' '7)- -Add'up10'be/ore'Jpcncnt '(MTD20)Pnntcd~lDee KayPTlIl!Cf\NewDelhi !IOOI~India AMENDMENTNO. 3 JANUARY 2001 TOIS2629:1985 RECOMMENDEDPRACfICEFORHOT-DIPGALVANIZING OF iron ANDSTEEL(FirstRevisioll)(Page8, )-Substitutethefollowingfor theexisting:' forgalvanizingshallconformto anyofthegradesspecifiedin IS 209 :1992 Zincingot(fourthrevision)orIS13229:1991 Zincforgalvanizing.'(MTD20)ReprograpbyUB iI,815,NewDelhi,India ISI2629 1985 IndianStandardRECOMMENDEDPRACTICEFORHOT- DIPGALVANIZINGOFIRONANDSTEEL( FirstRevision) Hot-Dip ,SprayedandDiffusio nCoatingsSectionalCommittee,SMDC28 ChairT1 UJn5 IUUV. "'NI41'IRepresIIIU"gIndUlnHotDipGalvaniz er'sAssociation,NewDelhiKarnamEngmcermgC orporalIOnLtd,BombaySteelAuthorityofIndi aLtd(RourkelaSteelPlant), '1aTheTrnplateCoofIndiaLtd,GolrnurrSteel Authority01 IndiaLtd(R&DCentreforIron&Stee l ),RanchiNationalTestHouse,CalcuttaMrmstr vofRailways,Nr-wDelhiMembersI'ltBlP.)

4 ' ]. \YYACRUIl8T&ME'l'ALLUR018TA88 ISTANTCUEIIl18T&ME' (Alternate) (Allernale) ) ]l[E~1 ICUA"IDH.\l\L\IlAJ'NI hvIndian~I{, \\IIeProductsLtd,SprcralSteelsLId,Bombay G'lut,K ..en.\ ,CalcuttaI ndianLeadImeInforrnauonCentre , ,~All\MrrnstryofDefr-nci(DGI), ,\T'rALIIAllYA (Alternate)SHRIS. 'OIlLlcctnra ,CalcuttaSlIlUM. (AllernaJ< (Alternate)SHRI]. (Alternate)SnurDAIISIIAN~J"OIl(Alternate ) :LAKANTA~ZcrurhSt e<1 PiP"Lid,HombayDltA. (Alternate) )( be aDIOfrmgcmcDtofcop}TlghtIlnd!rthelaidAct . (Ctmli_d!,,,mpa"I )M,mIH,sSUBIS' (,AI/",IIJ1,)SUBI ,Director(Struc&:Met)Rt/W'slJl/ingSteelA uthorityofIndiaLtd( BokaroSteelLtd),BobroSteelCityDirectorGe neral,lSI(Ex-offinoMfmM)S",6ta'JSURI S. K. GUPTAD eputyDirector(Metal.),lSIHot-DipGalvaniz ingSubcommittee,SMDC28 : 1 CotJllln"SaBIV. '.AaociatiOD,NewDelhiElectricalManufactu ringCoPvtLtd,CalcuttaHydelDesignsDirecto rate,ChandigarhHope'sMetalWindow.(India) Ltd,CalcuttaCentralElectricityAuthority, NewDelhiMfmbmSIUn :NTHY(Altnul' )SSBIV.

5 ~NJ)SBBI (A/I","11,) (AlI"ruJ/,)SURI ,BharatpurStlRIM. (A/I"MI,) (AI'''MI,)SSRI , N. (AI/"nal,)SURI A. , (A/I"JllJI,)JOINTDmECTOR(CHEX')Ministryo fRailwaysJOINTDmEcTOR(TI)-1(AII"na/,)SHR I R. (RourkelaSteelPlant),RourkelaDirectorate GeneralofTechnicalDevelopment,NewDelhiPO lIti&.TelegraphDepartment,CalcuttaTheTat aIron&.SteelCoLtd,JamshedpurZenithSteelP ipesLtd,BombayKamaniEngineeringCorporati onLtd,BombaySpecialSteelsLtd,Rombay(AIte rnat )TheIndianIron&SteelCoLtd,BurnpurDirecto rateGeneralofSupplies&Disposals,NewDelhi SBRI (.41"'TIIlI,)SHRI \IIAPATRA\SHRIS. (AII"TIIlI,)S~ ; (AI"'MI,) (AlI"TIIlI,)SHRI ~ \.SnHluPTASnurK. M. (.411,,"alt)5l1 JUVIJ,\YKAPounGuest,Keen,WilliamsLtd,How rah2 IS:2629 1985 IndianStandardRECOMMENDEDPRACTICEFORHOT- DIP GALVANIZING OF iron ANDSTEEL(FirstRevision) \V0 R ( FIrstRevision)wasadoptedbytheIndianStand ardsJnvututronon20 June198'),aflrrthedr,IftImahvedb)theHot- Dip,Spiavec!

6 AndDiffusion(;o,ltln~,>""I' ])1\1'>lllJ} thI~fieldI'hecontinuousgalva-niZIngproce ~shasbeenincludedIIIthisIC\ ,dclectsIngalvaruzcdco, ~~ ~'llval1l71nbI~ {zinccoatingto IrOIl or ste-elsurfaceforprou-ctron,\galll~t(ono- ionThe/InccoatimrhrvtlvprotertsthebaseJI lttalbyactingasanimperviousshrcldbetween themetalandtheatrnosplureandsecondlyaffo rdssacrrhrra!pro-tectionevenwhenmoderate lysiz edarea'>(~mrudia,forexample) ~alv,lf\lzlllgbath,themetalsurfacereacts withmolten710 Lto for m azmc-tron ,It pick-, lippurezincwhichsolidifiesoncoolingandfo rmstilt' >'etweentheferrousbasernaterialandthepur ezincandalsoresistscorrosionandabrasronI IItheeventofthepurezmclayerbeingremovedU ndersameconditionsofprorcssorcompo~l ,namely(a)thewetprocess,(0)thedryprocess ,and(c)thecontmu-ousgalvamzmqprocessCont llJUOUS galvamzmzprocessconstvtsof(leaningbasest eelsurfacebyfirstoxrchzmg'andsubsequentl yreducingthesur-faceoxidesundercontrolle datmosphereorbyanyotherm-Imecleaning3 IS.))

7 2629 ~heat-treatedinlint"annealing/normalizin gfurnacefollowedbycontinuousff'l' "lvanizing,whenthesheetemergesfromthezin cbath,theexcessmoltenzinc onthemis wipedoff by air or nofluxingin has gotadvantagesoverbothwetanddry processes withrespecttohighproductivity,controlofc oatingthickness,uniformityofcoatingalong thelength,bettercoatingadher-ence,less drossformation,bettersurfaceappearance, '1 Asummaryofdefects,alongwiththetypicalpho tographsforillustra-tion,commonlymetwith inthehot-dipgalvanizingpractice, ,theinformationgiveninthelastcolumnaidsi nspectorsininterpretingtheappearanceofth earticleandhelptheminarrivingat thisstandard, , ( FeZnls),whichis a compiesmixtureof zincandiron,forms in thegalvanizingbathas dross willvarybetween94 to to theworkinthedryprocessorspreadas is tohelpinkeepingthesurfaceofbothworkandmo ltenzinc ISI2629 seal ,mainlycontainingzincoxideandbasic zinccarbonate,thataccumulatesonthegalvan izedsurfaceexposedtowaterfilm ormoistatmosphe, ,however, shouldcontainminimumamountofsegregation, slaginclusions,rolled-inmillscale, ,however,isnotsoapparentintherangeofcomp ositionsencounteredinmildsteels as !

8 ROD-Castironreactwithzincdifferentlydepe ndingontheexactcomposition,inparticular, oil,greaseorpaint, sohandledinthedegreasingbathas to allowfreecirculationofliquidoverallparts , ,theworkshouldberaisedandloweredinordert oallowthedegreasingsolutiontoenterinacce ssibleareas,threadedsec-tions,etc,for ,thetemperatureofthesolutionmaybeusually keptbetween85and9000andtheimmersiontimev aryingfrom 1 ;manufacturers' ISt2629 ,thework shouldberinsedinhotwater(6 DoC)followed, if possible, by a finalrinsein Idealarrangementforrinsingwould be toprovideaninletandoutleton twooppositesides oftherinsingtank;theinletshouldbe in ,it may benecessarytoheattheparttobluingor this is anexpensiveanddifficultprocess, ,developburnt-onandpatchesatthesurfacewh ichare oflightcastingswhichwouldbedamaged, give aquickrinse inrunningwaterfollowedbycleaningwithone t toemploya use,thecommercialacidis dilutedtovariousstrengths,rangingfromone volumeofacidand59volumesofwaterfor a veryweakpickle toonevolumeofacidand9 volumesofwaterfor a ,whilethestronli(solu-tionshouldpicklesa tisfactorilyin 10 to , 4partsbyvolumeoftechnicalgradehydrochlor icacid(IIIIS :265-1976.))

9 ,asolutionconsistingof4partsofdilutehydr ochloricacid( I : I )and1partofhydrofluoricacidmay ( )andsulphuricacid( )solutionsmaybe used resultsareobtainedwhenit ishot( 60 toBO"C) Specrhcarionforhydrochloricacid(SICIJ rldrftlision).6 IS12629 (100-150gIL)-DilutetechnicalgHdcacidconf ormingto IS :265-1976* bepickled, , Acid Solution(100-150gIL)-Dilute6 to 8 mloftcchni-calgradeacidconformingtoIS:26 6-1<) ,thetemperatureoftill' , AcidSolution-Tomakethebestuseofthesoluti on,reasonablyclosecontrolof ~andwhentheironcontentreachestoabout100t o120gil,thesolutionshouldbediscarded.". , ,thewatercascadingfromoneintotheother,th atiscascadingfromthesecondtankintothefir sttank.".5 CleaningofStripintheContinuousGalvanizin gProcess(ARMCOS endizimirProcess)-Thecold-rolledstripisp assedthroughanoxidizingfurnaceattemperat urearound45() Speclficationforhydrochlor icacid(secondrlVlSlon).tSpecificationfor sulphuricacid(secondrtVlJlon).

10 7 IS : 2629 - ,inthedryprocess,isdippedin astrongsohi-tionof zincammoniumchloride( ZnCI . ),althoughammoniumchlorideisalsousedto isgenerallybetween200 to 400 80 over ahot-plateor in beabout120 Candshouldnotexceed150 C wet process, adeepfluxcoveris used on the zincbathandthe work isimmersedthroughthe fluxlayerwith ,as the fluxcoatingpicks upmoisturefrom the airandalso tends forgalvanizingis with-in flux crystalsandwatertomakeup for :to1 Freeacidcontentofthesolutionshouldclsobe checked,particularlyif may be used fordeterminationof freeacidbuttheactualtitrationshouldbemad eon a 100 mlsampleastheconcentrationofacidinthesol utionwill be very g of free acid per litre ofthesolutionispresent,itshouldbeneutral i-zed byaddingammoniasolutionoradditionof least98'5percentZnshouldbe used lessthan98'5percentby ISI2629 the dry process totheextent'ofabout0'005percent( 0 OCJ'percentMax)(0'05-007g/kgofzinc)