搜索
SteelTubingItisimpossibletogointodetailsabouteverytypeandshapeandgradeofsteelproductavailableorthatwemightbeinterestedin.Therearefartoomany,andavailabilitywillvarygreatlydependingonlocationandmanufacturer/supplier.Thatsaid,oneofthemostoftenused,mostoftenaskedabout,andmostoftenmisunderstoodproductsweuseisthevenerableroundsteeltubing.Roundsteeltubeiscommonlyavailableinanumberofindustrystandardsizes.Foranideaofthecommonindustrysizes(insidediameter(ID),outsidediameter(OD),andwallthickness)browsethesupplycatalogueofyourlocalsupplierorcheckthePirate4x4.comtechdatabaseHEREandespeciallyHERE.NotethatroundsteelmechanicaltubingisNORMALLYorderedandsuppliedbasedonaspecifiedODandwallthickness.TheIDistheresultoftheseformer2specs.Therearehoweversomeexceptionstothis-mostnotablyintrueseamlesstubing.HerearesomeFlash™graphicsofthedifferentsteeltubeformingprocessesthatIsnaggedfromtheexcellentSteelTubeInstituteofNorthAmericawebsite.Contnuous(buttwelded)pipeprocess.Thecontinuousprocessproducesafullrangeofpipesizesfromonlyafewdifferentwidthsofskelp.Thecoilsofskelp,orstrip,arefedintothemillandtheirendsweldedtogethertoprovideacontinuousflow.Thestrippassesthroughapre-heaterandintoafurnace.Theheatedstripisshapedintoanarcofabout270°inaformingstandbeforepassingintotheweldingstand.Thereanozzleappliesoxygentotheedgestofurtherheatthemastheyarepressedandweldedtogether.Thepipe'sODandwallthicknessarereducedinastretch-reducingmill.Pipeisthencuttolength,reducedtotherequiredsizeinasizingmillandwater-cooledbeforebeingstraightened.ItisthenreadyforfinishingTypicalElectricResistanceWeldedtubeprocessSteelstripisunwoundfromcoilsandside-trimmedtocontrolwidthandconditiontheedgesforwelding.Thestripthenpassesthroughaseriesofcontouredrollswhichprogressivelycold-formitintoacircularshape.Theedgesareforcedtogetherunderpressureandweldedbyheatingthesteeltotemperaturesbetween2200°Fand2600°Fusingcoppercontactsorcoilinduction.Weldflashisremovedfromthetheinsideandoutsidesurfacesofthenewly-formedpipe,andtheweldzoneisheattreatedtoensurehomogeneitybetweenthebasemetalandweld.Theweldissubjectedtoin-linenondestructivetesting,andthetubethenpassesthroughaseriesofsizingrollstoattainitsprecisefinisheddiameter.Itisthenstraightenedandcuttothedesiredfinishedlength.DOMtubebeingconstructed,startingasERWandthenbeingdrawnoveramandrel.ThemanufacturingprocessforDOMtubingbeginswithcoilsofsteel,whichareslittotheproperwidthforthedesiredtubesize.Thestripiscoldformedandpassedthroughanelectricresistancewelderwhichjoinstheedgestogether,underpressure,tocompletethetubularshape.Aftertestingtheweld'sintegrity,thetubingiscuttolengthforfurtherprocessingSeamlesstubeconstructionTheproductionprocessforseamlesstubebeginsbyheatingasteelbillettoabout2250°F.Thered-hotbilletisrotatedanddrawnbyrollsoverapiercingrod,ormandrel.Theactionoftherollscausesthemetaltoflowoverandaboutthemandreltocreateahollowtubeshell.Afterreheating,theshellismovedforwardoverasupportbarandishot-rolledinseveralreducing/sizingstandstothedesiredwallthicknessanddiameter.Thetube,whichhasgrownsignificantlyinlengthduringthepiercingandsizingprocesses,isthencutintosectionsandconveyedacrossacoolingbedtocoolslowlyintheair.Itthenreceiveswhateverfinishingprocessesareneededtomeetcustomerrequirements.Steeltubingisusuallysuppliedinoneofthefollowingforms:SeamlessTube.Thisisexpensiveandspecializedstuff.ItISNOTthecommonlyused(andmisreferenced)DOMtubing,asDOMtubingdoesindeedhaveaseam(albeit,almostinvisible-moredetailsbelow).Trueseamlesstubingisuncommonin4x4andautomotiveuse.Itisseamlessbecauseitismanufacturedbyaprocessknowasextrusionwhereasolidbarofsteelispierceddownthecenterwithadie,atunthinkablepressures,toformatube.Theprocesslookssimilartohowhollowpasta(macaronietc)ismade.Thereare2sub-typesofseamlesstube:ColdDrawnSeamless(CDS)TubeisnormallydrawntoO.D.andI.D.dimensionsandproducedtostandarddimensionaltolerances(thisdiffersfrommostothertypesoftubingexceptDOM).ItisnormallymadefromSAE1018andisconsideredgoodquality.HotFinishedSeamless(HFS)Tubeislowerincostthancolddrawnandmostapplicablewhereprecisedimensionsandsurfacequalityareofsecondaryimportance.ItismanufacturedtoO.D.andwalldimensionsfromSAE1026steelandisscaly,lessdependableandnotasstrongascolddrawntube.ElectricResistanceWelded(ERW)TubeERWisthemosteconomicalandreadilyavailabletypeofmechanicaltuning.Itisproducedbytakingaflatbarofsteelandrollingitintoatubeshape(picturerollingupanewspaper-butwithoutanyoverlap)andthenweldingtheseam-by,youguessedit-electricresistance-hencethename.Electricresistanceweldingissomewhatlikealong,continuousspotweld.It'softencomputercontrolledandextremelyconsistent.ERWisnormallySAE1010(forwallthickness16ga)orSAE1020.ERWtubecomesin2flavours:HotRolledERW(HREW)HREWisrolledintoatubeatelevatedtemperatures,usuallywayaboveroomtemperature.Thisproducesatubingthatismoremalleableandthereforeeasiertoformbutthatisalsonotasstrong,issuppliedcoveredwithscale,andnotasuniformindimensionascoldrolled.Itisalsoquiteabitcheaperthancoldrolled.ColdRolledERW(CREW)CREWismanufacturedbyap