ADE-872-AD

SAFE PRACTICES INOXY-FUEL WELDING & CUTTING

Controls Corporation of America1501 Harpers Road • Virginia Beach, Virginia 23454 USA

Phone: 757.422.8330 • Fax: 757.422.3125Phone Orders: 1.800.225.0473

www.concoa.com

OXY-FUELWELDING&CUTTING

SAFE PRACTICES IN

ADE-872-AD

CERTIFIED ISO 9001:2000

�

THIS PAGE INTENTIONALLY LEFT BLANK

�

TABLE OF CONTENTS

I. GENERALPRECAUTIONSFORTHEPREVENTIONOF:1.1 Burns 41.� HazardousFumeAccumulation 51.� FiresandExplosions 6

FORTHESAFEUSAGEOF:1.4 CompressedGasesand

CompressedGasEquipment 8

OTHER:1.5 UserResponsibilities 141.6 LeavingEquipmentUnattended 14

II. OXYFUELWELDINGANDCUTTINGSAFEPRACTICES�.1 ComplywithPrecautions1.1,

1.�,and1.� 15�.� CompressedGasSystem 15�.� Torch 18�.4 AdjustingPressures 19�.5 LightingTorch 19�.6 Shutdown 19�.7 BackfiresandFlashbacks �0

REFERENCESOURCES 24

4

INTRODUCTIONWe learn by experience. Learning safety throughpersonal experience is harmful, wasteful, andunwise.Lettheexperienceofothersteachyou.

This manual describes safe practices developedfrom experience in using welding and cuttingequipment. Continuous research, development,and field experience result in reliable equipmentand safe installation, operation, and servicingpractices. Accidents occur because of improperequipmentuseormaintenance.Somesafepracticesare based on common sense, others may requiretechnical volumes to explain. In any event, rulesshouldbefollowed.

Read and understand these safe practices beforeattempting to install, operate or service theequipment.Comply,asapplicable,tothepracticesforparticularequipmentused,andtheirinstructionmanualsforpersonalsafetyanthesafetyofothers.

Failure to observe these safe practices may causeserious injury or death. Habitual safety promotesconfidentequipmentuse.

Responsibilitiesofinstaller,user,andserviceman.Only a competent person, experienced with suchequipment should install, operate, and maintaintheequipment.

Thesesafepracticesaredividedintotwosections:I.GeneralPrecautions,commontoarcandoxyfuelweldingandcutting;andII.OxyfuelGasWeldingandCutting.

5

Reference Standards: Additional informationregarding welding and cutting safe practices canbefoundinStandardsandPamphletspublishedbyANSI,NFPA,AWS,andCGAlistedonpage�4.

TheNationalElectricalCode,OccupationalSafetyand Health Administration and local industrialcodes also provide mandatory requirements forequipmentinstallation,use,andservice.

I. GENERAL PRECAUTIONS FOR THE PREVENTION OF:1.1 Burns

1.1.1 WearProtectiveclothing--gauntletgloves,hat,andhighsafetytoeshoes.Keep shirt collar an pocket flapsbuttonedandwearcufflesstrouserstoprevententryofsparksandslag.

1.1.2 Wear safety goggles or glasses withside shields, appropriate filter lensesor plates (protected by clear coverglass).ThisisaMUSTforweldingorcutting(andchipping),toprotecttheeyes from radiant energy and flyingmetal. Replace cover glass whenbroken,pitted,or spattered.For eyeprotectionseeANSIZ87.1.

1.1.3 Donotwearoilyorgreasyclothingwhile welding or cutting.They arereadilyignitedbysparks.

1.1.4 Hot metal such as welding rod,electrodestubsandworkpiecesshouldneverbehandledwithoutgloves.

6

1.1.5 Medicalfirstaidandeyetreatment.Firstaidfacilitiesandaqualifiedfirstaidpersonshouldbeavailableforeachshiftunlessmedicalfacilitiesareclose-by for immediate treatment of flashburnsoftheeyesandskinburns.

1.1.6 Wear ear protection when workingoverheadorinaconfinedspace.Ahardhatshouldbewornwhenothersworkoverhead. See OSHA for allowablenoiselevelsandhearingprotection.

1.1.7 Donotuseflammablehairproductswhenweldingorcutting.Vaporsformsuchproductsareusuallycombustibleand are easily ignited by sparks.Suitableheadprotectionisrequired.

1.2 HazardousFumeAccumulation1.2.1 Adequate ventilation. Ventilate

as needed to prevent harmfulaccumulations of fumes and smokethat may be produced by weldingandcutting.ConsultANSIStandardZ49-1(listedin“ReferenceSources”)fordetailedventilationrequirements.NEVER USE OXYGEN TOVENTILATE THEWORKAREA.SeeANSIZ.49.1.

1.2.2 Lead-,Cadmium-,Zinc-,Mercury-,and Beryllium-bearing and similarmaterials,whenwelded(orcut)mayproduce harmful concentrations oftoxic fumes. Adequate local exhaustventilation must be used, or eachperson in the area as well as theoperator must wear an air-supplied

7

respirator. For beryllium, bothmustbeused.

1.2.3 Metals coated with or containingmaterialsthatemittoxicfumesshouldnotbeheatedunlesscoatingisremovedfromtheworksurface,theworkareaiswellventilated,ortheoperatorwearsanair-suppliedrespirator.

1.2.4 Workinaconfinedspaceonlywhileit’sbeingventilated,orwhenwearingan air-supplied respirator. Do NOTuseoxygenforventilation.

1.2.5 Gas leaks in a confined space, shutOFFgassupplyatsourceandremovetheweldingandcuttingequipmenttoavoidaccidental releaseofgases intothespaceshoulddownstreamvalvesbe opened inadvertently or closedimproperly.

1.2.6 Vapors from chlorinated solventscanbedecomposedbytheheatofthearc(orflame)toformPHOSGENE,a highly toxic gas, and other lung-and eye-irritating products. Theultraviolet(radiant)energyofthearccanalsodecomposetrichloroethylene,perchlorethyleneandotherchlorinatedsolventvaporstoformphosgene.DONOTWELD or cut where solventvaporscanbedrawnintotheweldingorcuttingatmosphereorwhereradiantenergycanpenetrate toatmospherescontaining even minute amounts ofthesolventvapors.

8

1.3 FiresandExplosions1.3.1 Causes of fire and explosion are:

combustibles reached by the arc,flame,flyingsparks,hotslagorheatedmaterial;misuseofcompressedgasesandcylinders;andshortcircuits.Donotattempttoinstalloruseequipmentbeforereceivingpropertraining,andreadingandunderstandingequipmentinstructions. Fire or explosion canoccuriftheequipmentisimproperlyinstalled, repaired or used. Repairsmustbemadebyqualifiedpersons.

BeAwareThat:flyingsparksorfallingslag can pass through cracks, alongpipes, through windows or doors,and through wall or floor openings,outof sightof thegoggledoperator.Sparksandslagcanfly�5feet.

TO PREVENT FIRES AND EXPLOSIONS:1.3.2 Keepequipmentcleanandoperable,

free of oil, grease, and (in electricalparts) of metallic particles that cancauseshortcircuits.

1.3.3 Obtain hot work permit from thesupervisor to ensure that adequateprecautions have been taken beforethe welding and cutting operationsarestarted.

1.3.4 Ifcombustiblesareinarea,doNOTweldorcut.Movethework,ifpractical,toanareafreeofcombustibles.Avoidpaintsprayrooms,diptanks,storageareas,ventilators.Iftheworkcannotbemoved,movecombustiblesatleast

9

�5 feet away, out of reach of sparksandheat;orprotect against ignitionwithsuitablesnug-fitting,fire-resistantshields.

1.3.5 Walls touching combustibles onopposite sides shouldnotbeweldedon(orcut).Walls,ceiling,andfloornearworkshouldbeprotectedbyheat-resistantshields.

1.3.6 Firewatchermustbestandingbywithsuitablefireextinguishingequipment,during and following welding orcuttingif:a. combustibles (including building

construction)arewithin�5feet.b.combustibles are further than �5

feetbutcanbeignitedbysparks.c. openings(concealedorvisible)in

floorsorwallswithin�5feetmayexposecombustiblestosparks.

d.combustibles adjacent to walls,ceilings, roofs,ormetalpartitionscan be ignited by radiant orconductedheat.

1.3.7 After work is done, check that areaisfreeofsparks,glowingembers,andflames.

1.3.8 An empty container or piping thatheld combustibles, or can produceflammablevaporswhenheated,mustneverbeweldedonor cut,unless ithas first been cleaned and preparedas described in AWS Bulletin F4.1,(listed in “Reference Sources.”)This includes: a thorough steamor caustic cleaning (or a solvent or

10

water washing, depending on thecombustible’s solubility) followedbypurgingandinertingwithnitrogenorcarbondioxide,andusingprotectiveequipmentasrecommendedinF4.1.Water-filling just below workinglevel may substitute for inerting insomeinstances,makingsurethatthespaceabovethewater level isventedtoprevent apressurebuildup in thecontainerasitisbeingheated.

1.3.9 Acontainerwithunknowncontentsshould be cleaned (see paragraphabove).DoNOTdependonsenseofsmellorsighttodetermineifitissafetoweldorcut.

1.3.10Hollowcastingsor containersmustbeventedbeforeweldingorcutting.Theycanexplodewhenheated.

1.3.11Explosive atmospheres. Never weldor cut where the air may containflammabledust,gas,orliquidvapors(suchasgasoline).

1.4 CompressedGasesandCompressedGasEquipment1.4.1 Standard precautions. Comply with

precautionsinthismanualandthosedetailedinCGAStandardP-1,SAFEHANDLING OF COMPRESSEDGASES IN CONTAINERS, (listedin“ReferenceSources,”page�4).

1.4.2 Pressureregulatorsa. Neverwithdrawgasfromacylinder

or pipeline except through anapproved pressure reducingregulator.

11

b.Regulator relief valve is designedtoprotectonlytheregulatorfromoverpressure;it isnotintendedtoprotectanydownstreamequipment.Providesuchprotectionwithoneormorereliefdevices.

c. Never connect a regulator to acylindercontaininggasotherthanthat for which the regulator wasdesigned.

d.Never use a regulator that hasloose or damaged parts, or is inquestionable condition. Underpressure,gascandangerouslypropellooseparts.

e. Remove regulator from cylinderwhen transporting unsecuredon a cart not designed for suchpurpose.

f. Remove faulty regulator fromservice immediately for repair(first close the cylinder valve anddrain the residual gas from theregulator.)

Thefollowingsymptomsindicateafaultyregulator:

Leaks-ifgasleaksexternally. Excessive creep - if the regulator

deliverypressurecontinuestorisewithdownstreamvalveclosed.

Faulty gauge - if gauge pointerdoesnotmoveoff“stop”pinwhenpressurized,norreturnto“stop”pinafterpressurerelease.

1�

g.Repa i r. Do NOT a t t emptrepair. Send faulty regulators tomanufacturer’s designated repaircenter. Special techniques, toolsand tests are used by personneltrainedintheseprocedures.

1.4.3 Cylindersmustbehandledcarefullytopreventleaksanddamagestotheirwalls,valves,orsafetydevices:a. Avoid electrical circuit contact

withcylindersincludingthirdrails,electricalwires,orweldingcircuits.They can produce arcs that maydamagethecylinderwall,causingapossibly serious accident.Neverstrikeanarconacylinder.

b.ICCorDOT/UNmarkingmustbeoneachcylinder.

c. Identifyinggascontent.Useonlycylinderswithnameofgasmarkedon them;donot relyon colorofcylindertoidentifycontents.Notifysupplier if content of cylinder isnot clearly identifiable. NEVERDEFACEor altername,number,orothermarkingsonacylinder.Itisillegalandhazardous.

d.Empties: Leave a little gas incylinder(10�5PSIG).Keepvalveclosed;replacecapssecurely;mark“MT”; keep them separate fromFULLSandreturnpromptly.

e. Prohibiteduse.Neveruseacylinderor its contents for other than itsintended use. NEVER use as asupport,roller,orclothesrack.

1�

f. Securefromfalling.Alwayschainorsecurecylindersuprightwhenaregulator(andhose)areconnectedtoit.

g.Passagewaysandworkareas.Keepcylindersclearofareaswheretheymaybestruckorknockedover.

h.Transporting cylinders. With acrane,useasecuresupportsuchasaplatformorcradledesignedforthepurpose.DoNOTliftcylindersoffthegroundbytheirvalvesorcaps,orbychains,slings,ormagnets.

i. Do NOT expose cylinders toexcessive heat, sparks, slag, andflame,etc.thatmaycauserupture.Do not allow contents to exceed1�0°F.

j. Protect cylinders, particularlyvalves from bumps, falls, fallingobjects, and weather. Keep capssecurelytightenedoncylindersnotinuseorbeingmoved.

k.Stuckvalve.DoNOTuseahammerormetalwrench(exceptspecialkeyfor acetylene) to open a cylindervalve that cannot be opened byhand.Notifyyoursupplier.

l. Mixinggases.Nevertrytomixanygasesinacylinder.

m.DoNOTtrytorefillanycylinderyourself.

n.Cylinderfittingsshouldneverbymodified or used for other thantheirintendedpurpose.

o.DoNOTdropcylinders.

14

1.4.4 Hosesa. Prohibited use. Never use hose

other than that designed for thespecified gas. A general hoseidentification rule is: red for fuelgas, green for oxygen, and blackforinertgases.

UseRMA-CGAGradeThoseforfuel gas (including acetylene) toprevent hose failures. Grades RandRMareforusewithacetyleneonly.

b.Use ferrules or clamps designedforthehose(notordinarywireorothersubstitute)toconnecthosestofittings.

c. No copper tubing splices. Useonlystandardbrassfittingstosplicehose.

d.Avoid longruns topreventkinksand abuse. Suspend hose offgroundorprotectitfromdamageby vehicles, sparks, slag or openflames.

e. Coilexcesshose topreventkinksand tangles. Do not drape coiledhosesaroundcylinders.

f. Examinehose regularly for leaks,wear, and loose connections.Immersepressuredhose inwater;bubblesindicateleaks.

g.Repair leaky or worn hose bycutting out damaged area andsplicing (as described in 1.4.4c,above).DoNOTusetape.

15

1.4.5 ProperConnectionsa. Clean cylinder valve outlet of

impurities that may clog orificesanddamageseatsbeforeconnectingregulator.Exceptforhydrogen,fuelgasandotherflammablegases,crackvalvemomentarily,pointingoutletawayfrompeopleandsourcingofignition. For hydrogen and otherfuelgases,wipewithaclean,lintlesscloth.

b.Matchregulatortocylinder.Beforeconnecting, be sure the regulatorlabel and cylinder marking agree,andtheregulatorinletandcylinderoutlet connections are proper fortheintendedservice.

c. Tighten connections. Whenassembling threaded connections,clean seats where necessary.Do not use pipe compound orlubricant.Tightenbutdonotforceconnection. If connection leaks,close cylinder valve, depressurizeline. Disassemble, clean, andretighten the valve. For metal-to-metalseating,usecorrectwrenches,availableformyoursupplier.ForO-ringconnections,hand-tighten.

d.Adapters. Avoid using adaptersbetweencylinderandregulator,butifunavoidable,useaCGAadapter(availablefromyoursupplier).Usetwo wrenches to tighten adapterwith both right and left handthreads.

16

e. Regulator out let (or hose)connectionsmaybe identifiedbyrighthandthreadsforoxygenandlefthandthreads(withgroovedhexonnutorshank)forfuelgas.

1.4.6 PressurizingSteps:a. Drain regulator of residual gas

through the regulator outlet byturning adjusting screwclockwisebefore opening cylinder (ormanifold)valves.Drainingpreventshigh pressure seat from beingexposed to heat of recompressionresulting from pressurization ofregulator. Leave adjusting screwengaged slightly on single-stageregulators.

b.Alwaysstandtosideofregulatorbeforeopeningcylindervalve.

c. Alwaysopenthecylindervalveveryslowly topreventa rapidbuildupof pressure within the regulator.After the full cylinder pressure isindicated on the regulator highpressuregauge,leavecylindervalvein the following position: Foroxygenandinertgases,openfullyto seal stemagainstpossible leak.Forfuelgas,opentolessthanoneturn to permit quick emergencyshutoff.

d.Use regulator pressure settingsrecommended in manufacturer’scharges (available from yoursupplier) for safe and efficientoperation of welding and cutting

17

equipment.Itwillreducebackfiringandchanceofflashbacks.

e. C h e c k f o r l e a k s o n f i r s tpressurization and regularlythereafter.Useanoxygenapprovedleak detection solution. Bubblesindicate a leak. Clean off leakdetectionliquid.

OTHER1.5 UserResponsibilities. Removeleaky

ordefectiveequipmentfromserviceimmediatelyandrepairthemonlyifrecommendedinequipmentinstructionmanual.Sendotherforrepairtomanufacturer’sdesignatedrepaircenterwherespecialtechniques,toolsandtestsareusedbytrainedpersonnel.RefertoUserResponsibilitystatementinequipmentmanual.

1.6 LeavingEquipmentUnattended.Closegassupplyatsourceanddraingasfromtheequipment.

1.7 RopeStaging-Supportshouldnotbeusedfromweldingorcuttingoperation;ropemayburn.

II. OXYFUEL WELDING AND CUTTING SAFE PRACTICES

Oxyfuelequipment,properlyusedcansafelyweld,heat,andcutmetals,butcarelessnessleadstosuchhazardsasfireandexplosions.Theequipmentmixesflammablefuelgasesandoxygenunderpressuretosupport a flame. Oxygen is not flammable, butvigorouslyacceleratescombustionoffuelgasesand

18

combustible material. Sparks, flying slag, fumes,hotmetal,aswellas theheat,arenormallyundercontrol.Thewiseoperatoravoidsunnecessaryrisksbyprotectinghimself andother fromaccidentsasdescribedhereandinreferencedsources.

2.1 ComplywithPrecautionsinsubsections1.1,1.2and1.3.

2.2 CompressedGasSystem2.2.1 Complywithprecautionsin1.4,with

CGA pamphlet P-1 (see “ReferenceSources” at rear) and with thefollowing:

2.2.2 SafetyDevicesa. Approved protective equipment

shallbeinstalledinfuelgaspipingtoprevent(1)backflowofoxygeninto the fuel gas supply system,(�)passageofaflashbackintothefuel gas supply system, and (�)development of back pressure inexcessofthepressureratingofthesystemcomponents.

b.Rever se f low check va lvesconnected to torch inlets preventbackflowofunwantedgasesintothehoseattachedtothetorch.Whilecheckvalveswillpreventbackflow,theyshouldnotberelieduponasasubstituteforindividuallypurgingthehosesbeforelightingthetorch.Check valves should be testedregularly tobe sure that theywillfunctionreliably.

c. Formaximumsafetyuseflashbackarrestors. CONCOA offers a lineof flash arrestors to help prevent

19

and protect against flashbackand backfires . However, nodevice can replace the necessityfor safe operating practices andproperlymaintainedoxyfueltorchequipment. CONCOA flashbackarrestors are designed to enhanceoperating procedures and helpprotect personnel and equipmentwhen these dangerous conditionsexist.

�.�.� Oxygena. Oxygen is NOT compressed air;

do NOT refer to it or use it ascompressed air. Oxygen is notflammablebutevenmaterialsthatdonotburninairusuallyburninoxygen.Those that burn slowlyin air can ignite easily and burnviolently in an oxygen enrichedatmosphere.

b.Never use oxygen to ventilateconfinedspaces.Useairtoreplaceatmosphericoxygenconsumedbyweldingorcutting.

c. Leaks shou ld be avo ided ,particularlyinconfinedspaces.

d.Oxygen-enriched (over 23%) oroxygen-depleted (under 19%)atmospheres should be avoided.DoNOTworkinorcreatesuchahazardouscondition.

e. Oxygen saturated clothes. It isdangerous to clean clothing withoxygen stream, or hang clothingon oxygen cylinders. Clothing

�0

saturated with oxygen will burnintensely when ignited. Shouldclothing be permeated, do notweld,cut,lightacigarette,orstartanykindof sparkorflame for atleast�0minutes,oruntilclothingisaired.

f. Grease,oil,oil-bearingmaterials,greasy gloves and rags, and othercombustiblesthatcanreadilyigniteinthepresenceofoxygenmustbekeptfromanyoxygenequipment.

g.Oxygen equipment should notbe contaminated by use in anyotherservice.Ifequipmentisusedforotherservice,donotuseitforoxygen.

h.Never use oxygen as a substitutefor air in sir-driven tools, in oilpreheating burners, to start aninternal combustion engine, toblow out pipelines, or to buildpressure(asinacontainer).

i. Cylinder storage. Keep oxygencylinders at least �0 feet fromfuel gas cylindersorother readilycombustiblematerialsparticularlygreaseoroil(orseparatedbyafive-footnoncombustiblebarrierhavingafireresistanceratingofatleast½hour).

j. Neverattempttocleananoxygengaugethathasbeencontaminatedwithoil.Replaceitwithanewoil-freegauge.

�1

k. Ifliquidoxygenisused,cylindersmust be transported, storedand used in upright position tomaintain gaseous state for safetydevices,andtopreventliquidfromreachingregulator.

2.2.4 FuelGasa. Refer to fuel gas by its correct

name.SayAcetylene,MAPP®Gas,etc.,notGAS.

b.LPandMAPP®Gascylindersmustbe transported, stored and usedin upright position to maintaingaseous state for safety devices,andtopreventliquidfromreachingregulator.

c. Acetylene cylinders must betransported, stored, and used inuprightpositiontoavoiddischargeof acetone with the gas duringuse.

d.Cylinder valve leak. Immediatelyclose valve on fuel gas cylinder ifopen.Ifvalvestillleaksorthefuseplug(orotherreliefdevice)orthecylinderitselfleaks:1. Immediately, remove cylinder

outdoors, away from possiblesourceofignition.

�.Tagcylinder,notingleakanditslocation.

�.Post“NoSmoking”warningsigninarea.

4.Notify cylinder supplier atonce.

5.Followsupplier’sinstruction.

��

e. Acetylenecylinderwrenchshouldbe left on an open cylinder valveandremovedafterclosingvalve.Useonly approved wrench, availablefromcylindersupplier.

f. Acetylene withdrawal. CGA5.�.�.1�orG-1callforawithdrawalrate“nottoexceed1/10(one-tenth)ofthecapacityofthecylinderperhourduring intermittentuse.Forfullwithdrawalofthecontentsofthecylinderonacontinuousbasis,the flow rate should be no morethan 1/15 (one-fifteenth) of thecapacityofthecylinderperhour.”

g.Neverdischargefuelgasnearanyflame, spark, or other source ofignition.

2.3 Torch2.3.1 Examine seating surface of torch

and connections before use for earanddamage.Wornordamagedpartsshouldbereplaced.

2.3.2 Repair. Do not attempt repair oftorches(orregulators).Iffaulty,sendthem for repair to manufacturer’sdesignated repair center wherespecial techniques, tools and testsare used by trained personnel. SeeUser Responsibility Statement inequipmentmanuals.

2.3.3 Torchisnotahammer.Neveruseittochipslag.Suchmisusecandistorttorch or tip to create hazards. Useappropriatetoolforthejob.

��

2.3.4 Torch tip cleaning should be doneonlywithspecifically-designedcleanersavailablefromyoursupplier.Cleantiporificesfrominsidetoavoidenlargingordamagingtheexitholes.

2.3.5 Valve stem leak. Close outlet valve.Tighten packing nut or repack thevalve. Use only packing supplied bymanufacturer. If seatingdevice is anO-ring,discarditforanewO-ring.

2.4 AdjustingPressures.Withtorchvalveclosed,turn regulator adjusting screws clockwiseuntil each delivery gauge shows pressureslightly higher than that recommendedin manufacturer’s chart (1.4.6d). Do notexceed15PSIGofacetylenepressureforanypurpose.

2.5 LightingTorch2.5.1 Purge lines daily before lighting to

remove air and other contaminantsfromhoses.Openeachtorchvalveinturnlongenoughforthepuregastopurgeoutanygasmixtures.Shutonevalve before opening the other. DoNOT purge in a confined space, inthepresenceofflameorothersourceofignition,ortowardpeople.

2.5.2 Point tip away from yourself andothers when lighting and usingtorch.

2.5.3 Use sparklighter or pilot light tolight torch. Do NOT use matchesor cigarette lighter, hand burns mayresult.

�4

2.5.4 Lightasfollows:Openfuelvalveandignitegasesflowingfromtip.Adjustfuelvalveforfullflowwithoutblowingoff. Adjust oxygen valve to desiredflame.

2.6 Shutdown2.6.1 ExtinguishingFlame:

a. Closeoxygenand(withoutdelay)fueltorchvalvestightly.

b.Check for gas leak from tip orvalves.

c. Leave torch in safe position topreventaccidentaldislodgingthatmyopenvalvesorcausedamage.

2.6.2 Leaving Equipment unattended(lunchorovernight):a. Extinguishflamebyclosingtorch

valves.b.Closecylindervalves.

2.6.3 Leavingequipmentunattended(overweekendorlonger):a. Extinguishflamebyclosingtorch

valvesandclosecylindervalve.b.Drain gas from regulators by

openingtorchvalves,ventinggasesinsafedirection,thenclosingvalvesone at a time. If in public area,disconnectandstoreequipmenttopreventunauthorizedoraccidentaluse,whichmaycreateahazard.

c. Purge lines before lighting orreuse.

2.6.4 Donotstorecompressedgascylinders(especiallywithconnectedequipment)in unventilated cabinets, vehicles orotherconfinedspaces.Gasleakingis

�5

aresultofimproperlyclosedvalvesorloosenedconnectionscanaccumulatein the unventilated area, creating acombustible mixture of gases.Thismixture will explode when ignitedorcanreducetheoxygencontent inthe breathing air to cause possibleasphyxiation.

2.7 BackfiresandFlashbacks2.7.1 Backfireanditscauses.Abackfireisa

loudnoiseproducedbytheexplosionofgasesatthecuttingorweldingtipusually following a minor flashbackof the flame, extinguishment, andre-ignition at the tip. Repeatedbackfirecancausetiptooverheatandeventuallycauseasustainedflashback.Causesare:a. Bringingtiptooclosetoworkor

touchingit.b.Foreignparticlesenteringtipand

impedinggasflow.c. Overheatedtip,suchascausedby

workingincorners.d.Tryingtooperatewithincorrector

toolowagasflow.2.7.2 Backfireremedy.Iftorchdoesnotstay

lit,closeoxygengasandfuelgasvalves- inthatorder.Relightfuelgaswithsparklighter only,NOTMATCHESOR CIGARETTE LIGHTER, and,NOToverhotwork.Ifstableflameisnotobtainedbyaddingoxygen,closetorchvalves,checktipcleanlinessandregulatorsettings,purge,andrelight.

�6

2.7.3 Flashbackanditscauses.Aflashbackisaburningbackoftheflameintothetip,orintoorthroughthetorch.Itisalsocalledasustainedburningintipor torch. A flashback can be causedbyfaultyormisusedequipment.Ifitdoesn’tcausefireorhoserupture,thenitmayproduceahissingorsquealingdue to burning inside torch or tip(usually at the mixer). Examples offaultyormisusedequipmentare:a. Failuretopurge.b.Incorrectpressures.c. Distortedorloosetipsoradapter

seats.d.Kinkedhoses.e. Cloggedtiportorchorifices.f. Overheatedtiportorch.

2.7.4 Tostopaflashback:a. Do NOT touch any parts of the

tip, mixer, or extension that maybehot.

b.When squealing sound is heard:the internal combustion mustbe extinguished immediatelyby shutting off torch fuel gasand oxygen valves in that order.Wait a MOMENT, OR UNTILNO SQUEALING is heard onreopening fuel gas valve, thenrelight.

c. Whensquealingisnotheard(andflashback is indicated by flow ofhotgasesfromtip):flameisinsidethe torch. Immediately shut offcylinder valves and wait. After

�7

five minutes, if torch, regulator,and cylinder are cool, disconnectequipment and inspect torch andregulatorforinnerdamage.

NOTE:CONCOA offers a line of flash arrestors to helppreventandprotectagainstflashbacksandbackfires.Nodevicecanreplacethenecessityforsafeoperatingpractices and properly maintained oxyfuel torchequipment. CONCOA flashback arrestors aredesigned to enhance operating procedures andhelpprotectpersonnelandequipmentwhenthesedangerousconditionsexist.

Check Valves prevent the reverse flow of mixedgases. Regulator Check Valves “B” size 8�0 4199Oxy.8�04�00Fuel.TorchCheckValves“B”size8�14146Oxy.,8�141�8Fuel.

FOR MAXIMUM SAFETY USE FLASHBACK ARRESTORS

Regulator MountedModel-78 Resettable

801 0786 “B” Size for Oxygen801 0789 “B” Size for Fuel Gas

Regulator MountedModel 53

801-0536 “B” Size for Oxygen801 0539 “B” Size for Fuel Gas

Torch MountedModel 460

801 1466 “B” Size for Oxygen801-1469 “B” Size for Fuel Gas

ULListed-MeetOSHARequirements-ComplywithIS)5175

�8

REFERENCE SOURCESFor more information, refer to the followingstandards or their latest revisions and comply asapplicable:

1. ANSIStandardZ49.1,SAFETYINWELDINGANDCUTTING,obtainablefromtheAmericanWeldingSociety,P.O.Box351040,Miami,FL33135.

2. ANSIStandardZ87.1,PRACTICEFOROCCUPATIONALANDEDUCATIONALEYEANDFACEPROTECTION,obtainablefromAmericanNationalStandardsInstitute,1430Broadway,NewYork,NY10018.

3. AmericanWeldingSocietyBulletinF4.1-80,RECOMMENDEDSAFEPRACTICESFORWELDINGANDCUTTINGCONTAINERSANDPIPINGTHATHAVEHELDHAZARDOUSSUBSTANCES,obtainablesameasitem1.

4. NFPAStandard51,OXYGEN-FUELGASSYSTEMSFORWELDINGANDCUTTING,obtainablefromtheNationalFireProtectionAssociation,BatterymarchPark,Quincy,MA02269.

5. NFPAStandard51B,CUTTINGANDWELDINGPROCESSES,obtainablesameasitem4.

6. CGAPamphletP-1,SAFEHANDLINGOFCOMPRESSEDGASESINCONTAINERS,obtainablefromtheCompressedGasAssociation,1235JeffersonDavisHwy.,Arlington,VA22202.

�9

7. OSHAStandard29CFR,Part1910,SubpartQ,WELDING<CUTTINGANDBRAZING,obtainablefromU.S.GovernmentPrintingOffice,Washington,DC20402

�0

THIS PAGE INTENTIONALLY LEFT BLANK

�1

THIS PAGE INTENTIONALLY LEFT BLANK

ADE-872-AD

SAFE PRACTICES INOXY-FUEL WELDING & CUTTING

Controls Corporation of America1501 Harpers Road • Virginia Beach, Virginia 23454 USA

Phone: 757.422.8330 • Fax: 757.422.3125Phone Orders: 1.800.225.0473

www.concoa.com

OXY-FUELWELDING&CUTTING

SAFE PRACTICES IN

ADE-872-AD

CERTIFIED ISO 9001:2000