氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件

OxyfuelCutting

andWeldingOxyfuelCutting

andWeldingOxyfuel:theprocessofcombiningpureoxygenwithacombustiblefuelgastoproduceaflameCanbeusedforwelding,brazing,cutting,andheatingmetalsOxygen&fuelgasesarestoredunderpressureincylindersandarereleasedasindividualgasesthroughvalves,regulators,andhoses.MixedastheyflowthroughtorchassembliesBurnastheyaredischargedthroughspecialtipsOxyfuel:theprocessofcombiFuelgases:Propane,naturalgas,propylene&acetyleneVaryintheirchemicalcompositionReactwiththemetalindifferentwaysFactorstoconsiderinselectingagas:Availability&costWeldingprocessoroperationtobeperformedThicknessofmetal&typeofweldedjointtobeproducedPhysicalpropertiesofmetalsChemicalpropertiesofmetalsFuelgases:Propane(C3H)Propane(C3H)Suppliedinaliquidformunderpositivepressure,whichvarieswithtemperatureMostoxyfuelcuttingtorchescanuseLPgas,butspecialhosesandcuttingtipsarerequired.ReadilyavailableinmostareasDuetocost,propanecuttingisheavilyusedinthemetalrecyclingindustry.SuppliedinaliquidformundePropylene(C3H6)Propylene(C3H6)Hasbeenusedforapproximately30yearsStableinbothliquidandgasstatesEconomicalProduceslittleslagHasahighheatvalueDoesnothavethewithdrawalpressurelimitationsthatarenecessarywithacetyleneApproximately5%propylene,87%propane&tracesofothergasesHasbeenusedforapproximatelAcetylene(C2H2)Acetylene(C2H2)MostwidelyusedfuelgasforweldingandcuttingapplicationsProducesacleanweldandacontrollableflameLessstableandmoreexpensivethanotherfuelgasesPerformsmostfunctionswellandiswidelyavailableMostwidelyusedfuelgasforCompressedNaturalGas(CH4)CompressedNaturalGas(CH4)Adaptableforcutting,soldering,brazing,andpreheatingAwatersealorblowbackvalvetopreventbackfiringintothegassupplylinemustprotectthenaturalgassource.Adaptableforcutting,solderiFactsAboutOxygen(O2)FactsAboutOxygen(O2)Odorless,colorless,tasteless&heavierthanairMakesupabout20%oftheatmosphereWillnotburnbyitselfProducedcommerciallybycausingairtoliquefyCompressedintosteelcylindersat1,800to2,400poundsperin2(psi)SupportscombustionandisexplosiveifhandledimproperlyCylindersizes=80to244ft3Odorless,colorless,tastelessFactsAboutAcetylene(C2H2)FactsAboutAcetylene(C2H2)Colorless,buthasaverydistinctodorHighlycombustibleCylindersizes=60to300ft3CylindercontainsaporoussubstancesaturatedwithliquidacetoneAcetyleneispumpedintothecylinder,displacingsomeoftheacetoneNotunderextremelyhighpressureFullcylinderispressurizedtoapproximately250psiMaynotbewithdrawnataratehigherthan

15psiColorless,buthasaverydistFunctionsofOxyfuelHeat FunctionsofOxyfuelHeat Oxyfuelcuttingofmildcarbonsteelheatsthemetaltorekindlingtemperature(1,400oFto1,800oF),thenoxidizesandblowstheslagfromthecutwithastreamofpureoxygen.Oxyfuelweldingfusestwopiecesofmetalbyheatingthemtothemeltingpointwithacombustiblemixtureofoxygenandfuelgas.CanbedonewithorwithouttheuseofaweldingrodBrazing:thejoiningofmetalsbyaddingbronzefillerSoftandhardsolders(lead&silveralloys)arethefillermaterialsusedinsoldering.Theoxyfuelflameisalsousedtobend,shape,preheat,stressrelieve,post-heat&tempermetal.OxyfuelcuttingofmildcarbonAssemblyoftheOxyfuelRigAssemblyoftheOxyfuelRigSecuretheoxygenandfuelgascylinderstoawall,aspecialcylindercart,oraspecialrackiftransportedtojobsitesinatruck.Removethevalveprotectioncapsandwipeoffanydirtaccumulationwithaclean,drycloth(freefromoilorgrease).Slightlyopen(crack)bothcylinderstomakesuretheydonotstickandtoblowoutanydirtordustlodgedinthevalve.Closethevalves.SecuretheoxygenandfuelgasCheckallvalves,connections,andsoftplugsforleakswithmildsoapywaterandacleanbrush.Attachtheregulatorstothecylinderspointingtowardtheskytopreventsomeonefromgettinginfrontoftheregulator.Theregulators,safetycheckvalves,andhosesshouldbetightenedsecurelywithawrench.Do

Notuseawrenchtoattachtheweldingtiporcuttingattachmenttothetorch.Checkallvalves,connections,氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件OxyfuelEquipmentOxyfuelEquipmentDesignedwithseveralbuilt-insafetyprecautions:Oxygenhosesareusuallygreen.Fuelgashosesarered.Alloxygenconnectionsandcylindershaveright-handthreads.Allfuelgasconnectionsandcylindershaveleft-handthreads.Fuelgasfittingshavea“V”notchcutaroundthetheoutsideoftheconnectors.Oxygenfittingsandconnectorsaresmooth.Designedwithseveralbuilt-inCylinders:

TwoRegulators:

TwosetsTwostageregulatorsarethesafesttouse.Hoses:Color-coded&specificallydesignedbasedonuseTypeR:designedspecificallyforacetyleneuseTypeT:approvedforallfuelgasesCylinders:氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件SafetyCheckValves:TwosetsrecommendedAttachbetweenregulatorsandhosesandbetweenhosesandtorchtopreventreverseflowofthegasesandflamethatcouldcausehosefires,regulatorruptures,andcylinderfiresTorchHandle:RegulatedbytwovalvesOftenequippedwithinternalreverseflowcheckvalvesCuttingAttachment:RegulatedbypreheatoxygencontrolvalveOperatedbydepressingthecuttingoxygenleverSafetyCheckValves:氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件TorchButtTorchButtCuttingAttachmentCuttingAttachmentCuttingTips:3to8preheatorificesand1oxygen-cuttingorificeDrillsizedeterminestipsizePropanetipisa2-piecetipwithatleast6preheatorificesWeldingTip:1orificeforgasmixtureSizeisdeterminedbydrillsizeoforificeCuttingTips:氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件SafetyPrecautionsSafetyPrecautionsKeepoilandgreaseawayfromallpartsoftheoxyfuelapparatus.Securethecylindersinanuprightpositionsotheycannotbeoverturned.Facetheregulatorgaugestowardtheskymakingitimpossibletostandinfrontofthem.Storeanduseoxyfuelunitsinwellventilatedareasadequatelyseparatedfromotheractivities.AcetylenepressureinthelinesshouldNEVERexceed15psi.KeepoilandgreaseawayfromOpentheacetylenecylindervalve?to?turns;ifitisthewheeltype,openalltheway.Useanapprovedsparklightertolightthetorch;neverusematchesorcigarettelighters.NEVERuseoxygentooperatepneumatictools,blowoutlines,inflatetires,ordustoffclothing.NEVERhangclothingoncylinders,runningtheriskofsaturatingthemwithoxygenandacetylene.DO

NOTconvertanacetyleneregulatortoanoxygenregulatororviceversa.Opentheacetylenecylinderva氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件Slowlyopentheoxygencylindervalvetopreventasuddensurgeofpressure.Releaseorloosentheregulatoradjustingscrewbeforeopeningacylindervalve.DO

NOTwalkwithalightedtorchorlaydownalightedtorch.PurgehosesbeforeattachingthetorchRepairhoseswithproperhosesplices,notfrictiontape.NEVERusealeakinghose.Testforleakswithsoapandwater,notmatches.Slowlyopentheoxygencylinde氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件Ifvalvesoncylindersarefaultyortootight,notifythesupplier;undueforcewouldbedangerous.Keepafireextinguisherhandyatalltimes.Dressproperlyandweareyeprotection.Preventheatandsparksfromgettingtocylindersandhoses.DO

NOTstrikeanarconacylinderorhitacylinderwithametalobject.NEVERuseacylinderasagroundinanelectricalcircuit.Ifvalvesoncylindersarefau氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件NEVERguess;getthecorrectinformationfromaqualifiedperson.Mark,isolate,orotherwisedesignateemptycylinders.Oxygenandfuelgascylinders(eitherfullorempty)MUSTbestoredseparatelyinaccordancewithsafetyandfirecodes.NEVERguess;getthecorrectiSet-UpProcedurefor

OxyfuelTorchNozzleSet-UpProcedurefor

OxyfuelChecktorchbodyforclosedvalves.Checkregulatorforlooseregulatoradjustingscrew.Openacetylenecylindervalve?to?turn(wheel-typevalvesoneturn)maximum.Turnacetyleneregulatoradjustingscrewtodesiredworkingpressure.Openoxygencylindervalvecompletely.Turnoxygenregulatoradjustingscrewtodesiredworkingpressure.ChecktorchbodyforclosedvaCrackacetylenetorchvalveandlightthetorch,openacetylenetorchvalveuntilsootdisappears.Openoxygentorchvalvetoadjusttoneutralflame;noacetylenefeatherandsharpinnerconeWhenwelding,theratioofoxygentoacetyleneisapproximately1:1.Oxygenandacetylenesettingswillvarydependingontheattachmenttipandthicknessofmetaltocutorweld.CrackacetylenetorchvalveanTypesofOxyfuelFlamesTypesofOxyfuelFlames氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件ShutdownProcedure

forTorchNozzleShutdownProcedure

forTorchTurnoffacetylenevalveontorchbutt.NEVERturnoffoxygenfirst.Turnoffoxygenvalveontorchbutt.Closeacetylenecylindervalve.Bleedacetylenehosebyopeningacetylenetorchvalve;closevalve.Backacetyleneregulatoradjustingscrewuntilloose.Closeoxygencylindervalve.TurnoffacetylenevalveontoBleedoxygenhosebyopeningoxygentorchvalve;closevalve.Backoxygenregulatoradjustingscrewuntilloose.Recheckvalvesforclosure,rolluphoses.Ifrigisnottobeusedforsometime, removetheregulatorsandputthe safetycapsbackonthecylinders.

NEVERleaveequipmentunder pressure24hoursaday.BleedoxygenhosebyopeningoCuttingMetalsCuttingMetalsMetaltobecutshouldbeclean,markedwithapunchorsoapstone,andplacedinasuitablepositionforcutting.DO

NOTcutoveraconcretefloor.Useacontainerorspecialcuttingtabledevicetocatchthemoltenmetal.Oxyfuelcuttingislimitedtoferrousmetals.Steelswithahightungstenorchromiumcontentorstainlesssteelcannotbecutwithoxyfuel.Castironismoredifficulttocutthansteel.AnexcessfuelflameisusedMoreoxygenpressureisneededMetaltobecutshouldbecleaStepstoFollowinMakingaCutHoldblowpipeperpendiculartosurfaceofmetalunlessbevelsaretobecutHoldtheflameinnerconeabout1/16to1/8inchabovetheplate.ProperdistanceawayfromplatewillpreventmetalfromstickingtothetipHoldtipsothattwopreheatholesareinlinewiththecutHoldtorchatedgeofmetaluntilmetalbeginstomeltTopoftorchmaybeslantedtowardthecut&changedtoaverticalpositionascutprogressesStepstoFollowinMakingaCu氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件PressdownslowlyonthecuttingoxygenleveruntilcuttingvalveiscompletelyopenWhenthecutisthroughthemetal,movetorchalongmarkTilttorchtiptowarddirectionofcutonthinmetalItshouldbeheldinaverticalpositiononthickmetalPressdownslowlyonthecutti氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件MovetorchslowlyalongsurfaceoroxygenstreamwillnotpasscompletelythroughthickmetalTorestartthecut,releasecuttingleverandreheatmetalagainbeforepressingcuttinglevelLosingthecutmaycauseirregularedges.Whenbevelingplateedgesorcuttingatanangle,leanthetipatthedesiredangleandholdthetorchparalleltothework.MovetorchslowlyalongsurfacCorrectCutNoticethatthetopedgeissquareandthatthedraglinesshowaslightcurve.OxygenPressureTooLowProducesacutwithroughsurface,makesitdifficulttoholdcutandresultsinslowspeedwithtoomuchlag.CorrectCutSpeedTooFastProducesaroughcutwithpronounceddraglineverysimilartotoolowoxygenpressure.OxygenPressureTooHighProducesaroughsurface,meltsdowntopedgeandwastesoxygen.SpeedTooFastTooMuchAcetyleneinPreheatsReducescuttingspeedapproximately25%.Formscarbondepositsoncutsurfaceandwastesacetylene.CorrectCutHerethefactorsoftipsize,pressuresandspeedarecorrect…resultsinsquaretopedgeanduniformnarrowkerf.TooMuchAcetyleneinPreheatsPreheatsTooHeavyTopedgeismelteddown,kerfirregularandexcessgasisconsumedbythepreheatflame.PreheatsTooSmallWastestimeasmaximumspeedcannotbeobtained.Lowcuttingspeedresultsingougesatbottomedgeofcut.PreheatsTooHeavyOversizeTipProducesakerfwhichistoowide,causingnotonlyawasteofplatebutalsoawasteofbothgases.UndersizeTipInefficientcutbecausepiecewillnotdropwhenendisreachedasslaghasnotclearedthekerfandcuttingtimewillbeexcessive.OversizeTipStepstoFollowWhenPiercingHolesHoldblowpipetipperpendiculartothesurfaceuntilaspotonthesurfacebeginstomeltRaisetorchuntiltipisabout1/2”fromthesurfaceandslowlypresstheleverastorchisraisedMovetiptoonesideoftheheatedareasothattheslagcanbeblownoutStepstoFollowWhenPiercingMoveinnerconewithinabout1/8”fromthesurfaceandmakethecutontheinsideedgeoftheholeTofacilitatethecuttingofaholeinthickmetal,drillahole1/4”indiameterorlargerandstartthepiercinginthishole.Moveinnerconewithinabout1氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件CareofOxyfuelTipsCareofOxyfuelTipsTipsfrequentlybecomespatteredwithmetalorothermaterialsthatmaycauseinferiorwork.Tocleantips:Rubemerycloth,steelwool,orthefileonatipcleanertocleanandsquarethetippoint.Insertthecorrectsizecleanerintoeachorifice.Pushinandpullout;donottwistorbendthecleaner.Openoxygenslightlyduringthisproceduretoblowoutforeignparticles.Careshouldbetakennottodamagethethreadsandseatsofthetips.TipsfrequentlybecomespatterPreparingMetalforWeldingPreparingMetalforWeldingFreethemetalfromoil,paint,grease,dirt,rust,andotherforeignmaterial.Heatthemetalwiththetorch,andthencleanwithawirebrush.Thickmetalshouldbebeveledwithagrinderortorch.Aligntheplatestobeweldedandtackweldthemtopreventwarping.Freethemetalfromoil,paintProperWeldingTipPositionsProperWeldingTipPositionsTheblowpipecanbeheldlikeahammerwhenstandingorlikeapencilwhensitting.Thetipandweldingrodshouldbeheldata45oangletotheworksurface.Theinnerconeflameshouldbe1/16”to1/8”abovethemetal.Preheatingthemetalisveryimportantinmakingasuccessfulweld;therefore,theflameshouldbemovedinthedirectionoftheweld,andtheconeshouldstayinsidethepuddle.TheblowpipecanbeheldlikeOxyfuelWeldingProceduresOxyfuelWeldingProceduresOneofthemostimportantstepsinlearningtoweldwithoxyfuelistocarryamoltenpuddleofmetalalongthelineorseamofpartstobejoined.Forming&runningthebead:Flameheldatstartingpointuntilabrightroundpool(1/4”to3/8”indiameter)isformedWeldingspeedshouldbeadaptedtomaintainauniformpuddlewidth.Innerconeheld1/16”to1/8”abovesurfaceSlowspeed:flameburnsaholethroughthemetalFastspeed:beadwillbeirregularandnarrowOneofthemostimportantstep氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件MostcommonmovementpatternforfusionweldingisthecircularmotionZigzagmotionisbestwhenusingafillerrodTorchshouldbeheldatabout45otothesurfaceWeldingrodshouldbeheldat45o,butslantedawayfromthetorchtipRoddiametershouldbeequaltothethicknessofthemetalTorchmaybeheldsotipispointedindirectionofweld(forehandwelding)ortippointedtowardweld(backhandwelding)Mostcommonmovementpatternf氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件氧乙炔-切割和焊接-Oxyfuel-Cutting-and-Welding課件TypesofWeldedJointsTypesofWeldedJointsMostareeitherbuttjointsorfilletjointsButtwelding:Twopiecesofmetalarebuttedtogetherandwelded,withorwithoutbevelingFilletwelding:MetalpiecesarejoinedtogetherforminganangleMostareeitherbuttjointsorWeldingCastIronWeldingCastIronUsuallydonewithabronzerod,unlessthecolorofthebasemetalmustbematchedCastironrodsrequirehigherpreheatingthanbronzerods.UsuallydonewithabronzerodPracticeprocedureforweldingcastiron:Selectthecorrectflux.Cleanandbeveltheedgesofthestock.Usea3/16”rodwithaneutralflameandtacktheendstogether.Heattherodtiptoared-coloredheatanddipitintheflux,thendipthetipintothemoltenpuddleofcastiron.Weldinthesamemannerasfusionweldingonmildsteel.Dipthehottipoftherodinfluxfromtimetotime.Ifbubblesappear,addmoreflux.PracticeprocedureforweldingPracticeProcedureforBrazeWelding:DoesnotrequireextremelyhighweldingtemperatureCleansurfacetobeweldedBevelandalignedgesofthemetalUseneutralflameandheattheendoftherodanddipintothefluxHeattheareatobeweldedtoadullredandtackendsApplyfluxfromrodonheatedarea,thenpassrodintoflameanddepositasmallamountofbronzeattheintervalsuntiltheweldiscomplete.Addfluxfromtimetotime.PracticeProcedureforBrazeWHardsurfacingHardsurfacingApplicationofanallalloymaterialtoanothermetalforthepurposeofreducingwearProcedure:Thoroughlycleanthemetalbeforeapplyingalloy.Placethematerialtobehardsurfacedinaflatposition.Heatasmallsectionoftheareawithanexcessacetyleneflameuntilthemetalbeginstosweat.ApplicationofanallalloymaTouchthetipofthealloyrodtothesurfaceandmeltenoughoftherodtoformanalloycover1/16”thickandadesirablewidthwithoutheatingthebasemetaltoameltingpoint.Maintainthehardsurfacingtemperatureinfrontofthepathonthehardmetal.Addjustenoughrodtothemetaltomaintainauniformthicknessandwidth.Hardsurfacedmetalshouldbeallowedtocoolslowly.Drylimeservesasagoodcoverforcoolingmetal.Besuretofollowrecommendationsofthemanufacturerofthehardsurfacingrods.TouchthetipofthealloyrodAmericanWelding

SocietyCertificationAmericanWelding

SocietyCertTheAmericanWeldingSociety(AWS)istheprofessionalorganizationresponsibleforsettingstandardsforthecertificationofweldors.1ststepinbecomingahighlyskilledcraftsmanistocertifyasanEntryLevelWeldorTheAmericanWeldingSociety(CertificationprocessforEntryLevelWeldorconsistsof:APracticalKnowledgeTest:Welding/cuttingtheoryWelding/cuttinginspection&testingSkill-relatedvocabularyMetalidentificationWeldingvariablesElectricalfundamentalsWeldingsymbolinterpretationFabricationprinciples&practicesSafetyRequiresaminimumpassinggradeof75%,withaminimumscoreof90%onsafety-relatedquestionsCertificationprocessforEntrAPerformanceTest:ReadingweldingsymbolsFollowingwrittenproceduresCuttingpartstoproperspecificationsFittingpartscorrectlyPerformingspecificweldingtechniquesPreparetestcouponbyoxyfuel(OFC)andplasma-arccutting(PAC)IncludesbothcuttingstraightlinesandpiercingholesAPerformanceTest:CheckingforCylinderLeaksCheckingforCylinderLeaksStandardacetylenecylindercontainsfrom90to154ft3,storedinaporousfillersaturatedwithacetoneCylindersarefilledunderpressureandmaydevelopleaksaroundthevalvestemorinthe“softplugs”Anacetylenecylinderleakingforanentireweekendintoaclosedfacilitycanbecomeatragedyofsignificant