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SpecificationDOT-4L(HSE)WeldedInsulatedCylindersIssue3March1999.I:\THSDA5\HARRY\CYL1Iss3March1999Contents1.0Type,sizeandservicepressureanddesignservicetemperature.2.0CertificateofCompliance.3.0DutiesofInspector.4.0Material.5.0IdentificationofMaterial.6.0Defects.7.0Manufacture.8.0Welding.9.0WallThickness.10.0HeatTreatment.11.0OpeningsinCylinder.12.0SafetyReliefDevicesandProtectionforValves,SafetyDevicesandOtherConnections.13.0PressureTest.14.0PhysicalTest.15.0RadiographicExamination.16.0Rejectedcylinders.17.0Authorisedmaterialsofconstruction.18.0Markings.19.0Inspector'sreport.Appendix1Inspector'sreportform.I:\THSDA5\HARRY\CYL1Iss3March19991.0Type,size,servicepressureanddesignservicetemperature.1.1ADOT4L(HSE)cylinderisafusionweldedinsulatedcylinderwithawatercapacity(nominal)notover454kg(1000pounds)andaservicepressureofatleast2.76bar(40p.s.i.g.)butnotgreaterthan34.5bar(500p.s.i.g.)conformingtothefollowingrequirements:1.1.1Forliquefiedhydrogenservice,thecylindersmustbedesignedtostandonend,withtheaxisofthecylindricalportionvertical.1.1.2Thedesignservicetemperatureisthecoldesttemperatureforwhichacylinderissuitable.Therequireddesignservicetemperaturesforeachcryogenicliquidisasfollows:Minus160oC(2560F)orcolderLNGMinus196oC(3200F)orcolderOxygenMinus196oC(3200F)orcolderNitrogen...................................Minus246oC(4110F)orcolderNeon........................................Minus253oC(4230F)orcolderHydrogen................................Minus269oC(4520F)orcolderHelium....................................Minus196oC(3200F)orcolderArgon......................................DesignservicetemperatureCryogenicliquid2.0CertificateofComplianceTheInspectionBodyapprovedbytheHSEshallcertifythatthemanufacture,inspectionandtestingofthecylinderswascarriedoutincompliancewiththerequirementsofthisspecification.3.0DutiesofInspector3.1Inspectallmaterialandrejectanynotcomplyingwiththerequirementsofthisspecification.3.2Verifychemicalanalysisofeach'heat'(cast)ofmaterialsbyanalysisorbyobtainingcertifiedanalysis:providedthatacertificatefromthemanufacturerthereof,givingsufficientdatatoindicatecompliancewithrequirementsisacceptablewhenverifiedbycheckanalysisofsamples,takenfromonecylinderoutofeachlotof200orless.3.3Verifycomplianceofcylinderswithspecificationrequirementsincluding:markings;conditionofinterior;tests;threads;heattreatment.Obtainsamplesforalltestsandcheckchemicalanalysis;witnessalltests;reportvolumetriccapacity;tareweightandminimumthicknessofwallnotedandrecorded.3.4Furnishcompletetestreportsrequiredbythisspecificationtothemakerofthecylinderand,uponrequest,tothepurchaser.Thetestreportshallberetainedbytheinspectorforfifteenyearsfromtheoriginaltestdateofthecylinder.I:\THSDA5\HARRY\CYL1Iss3March19994.0Material.4.1Materialusedintheconstructionofthisspecificationmustconformtothefollowing:4.1.1Innercontainmentvessel(cylinder).DesignationsandlimitingchemicalcompositionsofsteelauthorisedbythisspecificationshallbeasshowninTable1,section17.14.1.2Outerjacket.Steeloraluminiummaybeusedsubjecttotherequirementsofsection17.2.5.0IdentificationofMaterial.Materialmustbeidentifiedbyanysuitablemethod.6.0.DefectsMaterialwithseams,cracks,laminationsorotherinjuriousdefects,notauthorised.7.0Manufacture.Cylindersmustbemanufacturedusingequipmentandprocessesadequatetoensurethateachcylinderproducedconformstotherequirementsofthissub-partandtothefollowingrequirements:7.1Dirtandscaletoberemovedasnecessarytoaffordproperinspection.Nodefectispermittedthatislikelytoweakenthefinishedcylinderappreciably.Areasonablysmoothanduniformsurfacefinishisrequired.Theshellportionmustbeareasonablytruecylinder.7.2Theheadsmustbeseamless,concavesidetothepressure,hemisphericalorellipsoidalinshapewiththemajordiameternotmorethantwicetheminordiameter.Minimumthicknessofheadsmaynotbelessthan90percentoftherequiredthicknessofthesidewall.Theheadsmustbereasonablytruetoshape,havenoabruptshapechangesandtheskirtsmustbereasonablytruetoround.7.3Thesurfaceofthecylindermustbeinsulated.Theinsulatingmaterialmustbenon-combustible.Theinsulationonnon-evacuatedjacketsmustbecoveredwithasteeljacketnotlessthan1.5mm(0.060-inch)thickoranaluminiumjacketnotlessthan1.75mm(0.070inch)thick,soconstructedthatmoisturecannotcomeincontactwiththeinsulatingmaterial.Ifavacuumismaintainedintheinsulationspace,theevacuatedjacketmustbedesignedforaminimumcollapsingpressureof2bar(30p.s.i.g.)differentialwhethermadeofsteeloraluminium.Theconstructionmustbesuchthatthetotalheattransfer,fromtheatmosphereatambienttemperaturetothecontentsofthecylinder,willnotexceed0.0005Btuperhour,perFahrenheitdegreedifferentialintemperature,perpoundofwatercapacityofthecylinder.Forhydrogen,cryogenicliquidservice,thetotalheattransfer,withatemperaturedifferentialof271oC(520oF),maynotexceedthatrequiredtovent0.83m3(30SCF)ofhydrogengasperhour.I:\THSDA5\HARRY\CYL1Iss3March19997.4Foracylinderhavingadesignservicetemperaturecolderthanminus196oC(minus3200F),acalculationofthemaximumweightofcontentsmustbemadeandthatweightmustbemarkedonthecylinder.7.5Weldingproced