ANSI Z49-1 (1967) Safety in Welding and Cutting

7/29/2019 ANSI Z49-1 (1967) Safety in Welding and Cutting

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USAS Z49.1.1967U.D.C.621.791 :614.8

USA Standard

Safety in Weldingand Cutting

Third EditionSuperseding 1.9.58 Edition

Prepared by USA Standmds Committee Z49Under the Sponsorship of Americlln W e l d i n ~ Society

Edward A. FentonTechnical Di1'ector

Copyright 1968 byAMERICAN WELDING SOCIETY, INC.

345 East 47th Street, New York, N, Y. 10017

PRINTED IN THE UNITED STATES OF AMERICASCONI> PaiNTING, Al'l\IL 196H

Price $4.00


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P e r s o n n e l

USA Standards Committee Z49

F. C. Saacke CHAIRMANH. W. Speicher VICE-CHAIRMANR.Alann SECRETARY

AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIALHYGIENISTS:C. H. Powell, Occupational Health Research lind Traininp; Facility1. Kingsley, (Alternate), New Yorle State Department of LaborAMERICAN GAS ASSOCIATION:V. A. Howell. Long Island Lilthting Co.H. W. Becker. (Alternate), Americlln Gas AssociationAMERICAN INDUSTRIAL HYGIENE ASSOCIATION:H. W. Speicher, Wl'StinJ.thouse Electric Corp.J. J. Ferry, (Alternate), General Electric CO.

AMERICAN INSURANCE ASSOCIATION:W. M. Apgar!, Americun Insunmce AssociationW. H. Van Arnum:.!, American Insurunce A . ~ s o d u t i o nAMERICAN IRON AND STEEL INSTITUTE:J. Matust'k, Inland Steel CO.AMERICAN MUTUAL INSURANCE ALLIANCE:P. LanJ:(t', Employers u t u a L ~ of WousauC. S. Luubly. (Alternate), C e l a n c , ~ t ' Corp.AMERICAN PETROLEUM INSTITUTE:K. C. Lowe:!, American Oil CO.J. F. McKenna, (Alternate), AmC'rican Pt,trol(:'um InstitutlAMERICAN PUBLIC HEALTH ASSOCIATION:W. J. Hol1and, Public Health Servic('AMERICAN SOCIETY OF MECHANICAL ENGINEERS:A. N. KUJ,(ler. Air Rcduttion Co., Inc.C. O. HOJ,(lunci, (Alternate), Alma T('chnk:11 Ct'nt!' rAMERICAN SOCIETY OF SAFETY ENGINEEHS:E. O. Kumlt'r. Thompson Ramo WooldriuJ,(l', Inc.P. W. Chatterton, (Alternate), Aml'riclIn Society (If SIIf'l'IY EIIs.lint'(rsAMERICAN WELDING SOCIETY:F. C. Saackt'. Air RI,(hwtinn Cu., Inc.ASSOCIATED FACTORY MUTUAL FIHE INSURANCECOMPANIES:L. H. 1?landC'rs, Jr., Factory Mutual EnJ,(illl'('riuj.( DivisiunAUTOMOBILE MANUF ACTUHEHS ASSOCIATION:R. W. Battl'n. Chrysler Elll(inl' PlantCANADIAN STANDARDS ASSOCIATION:E. Mastromattco, M.D., (Liaison M('ml>l'r), Canadian D"purtml' l I! 01 11"011111


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COMPRESSED GAS ASSOCIATION:J. J. Crowe, Air Reduction Co., Inc.L. C. Matthews, (Alte rnate ), Union Carbide Corp.INDUSTRIAL MEDICAL ASSOCIATION:C. Demehl, M.D., Union Carbide Corp.INDUSTRIAL SAFETY EQUIPMENT ASSOCIATION, INC.:R. C. Tressler, Fiber-Metal P r o d u e t ~ Co.C. N. Sumwalt, Jr., (Alternate), Industrial Safety Equipment Association, Inc.INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS:J. H. Lampe, Old Dominion CollegeINTERNATIONAL ASSOCIATION OF GOVERNMENTAL LABOROFFICIALS:R. L. H i g ~ i n l i , New Jersey Department of Labor and IndustryC. F. Haaren, (Alternate), New Jersey Department of Labor and IndustryMECHANICAL CONTRACTORS ASSOCIATION OF AMERIGA:w. E. M a l o n e y ~ , Joseph Dlwis, Inc.H. K. Raislerll , Raisler Corp.NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION:A. N. Kuglerll, Air Reduction Co., Inc.N. C. Schreiner. (A lternate), Union Carhide Corp.NATIONAL FIRE PROTECTION ASSOCIATION:W. L. Walls, National Fire Protection AssociationNATIONAL SAFETY COUNCIL:H. J. Weber, Nneriean Foundrymen's SucietyRESISTANCE WELDER MANUFACTURERS ASSOCIATION:J. Morrissey, Resistance Welder Corp.SHIPBUILDERS COUNCIL OF AMERICA:T. B. Smith, Bethlehem Steel CO.U. S. DEPARTMENT OF THE AIR FORCE:Maj. O:W. Kittilstad1, U. S. Department of the Air ForeeLt. Col. C. C. Feightnerd, U. S. Department of thn Air Foret'Lt. Col. R. L. P('tersonO, U. S. Departmt'nt of the Air ForceU. S. DEPARTMENT OF THE ARMY:W. M. Kennldy, U. S. Army, OfHce of Chit'f Ill' Engfnl'trsC. F. SpraJ,(ue, III, (Alternatt'), U. S. Anny Environmental HYJ(ienc A ~ t ' n ( ' yU. S. DEPARTMENT OF LABOR, BUREAU OF LABORSTANDARDS:. W. J. Jones, Office of Occupatiollal Safety .A. D. Morehousl.', (Altprnate), OffiCl' of Occupational SafetyU. S. DEPARTMENT OF THE NAVY, OFFICE OF INDUSTlUALRELATIONS:R. W. Webster, Snfl'ty Division, Officc of Industrial RtlationsU. S. DEPARTMENT OF THE NAVY, NAVAL SHIPSENGINEERING CENTER:E. W. Eschbacher, Naval Ship I':nJ,linl'l'rinJ,( CenkrU. S. PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH,EDUCATION AND WELFARE:J. H. Fanney, Jr., Occnpntionnl fh:tlth Rt'sl'nnh &TraininJ,( Facility

1Appointed, Septemher 1966!lResigned, A u ~ u s t 1966:J Appointed, Septembl'r 1966

I Appointc'u, May 1967ResiJ,(lleu, May 1967o Resigned, July 19677 Appointtod. January 1967RAppointed, October 1965;Resigned, January 1967II Resigned, September 1965


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Table of ContentsF01'ewordCitation

1. Scope " ............................................................................... 12. Deftnltions .................................... ........................................... 13. Installation and Operation of Oxygen-Fuel Gas Systemsfor Welding and CuHing .............. ...... .............................. 2

3.1 General Provisions .. ...... ... ................ ................. ....... 23.2 Cylinders and Containers.. .. ..... .......................... .......... 33.3 Manifolding of Cylinders ... ...... ....... .............. 93.4 Service Piping Systems ..... ... ................................... 113.5 Protective Eq1dpment, Hose, and Regulators.. . . . 173.6 Acetylene Generators.......... ........... .......... .......... 213.7 Calcium Carbide S to rage . . . . . . ... .. 283.B Public Exhibitions and Demonstrations .. .., 30

4. Application, Installation and Operation of Arc Welding andCuHing Equipment ............ .. ......... 314.1 General ... ..... .. ... ........ .... ......... 314.2 Application of Arc Welding Equipment 324.3 Installation of Arc Welcling Equipment 354.4 Operation and Maintenance 37

5. Installation and Operation of Resistance Welding Equipment5.1 General.. . . . . . . . . ................. 405.2 Spot and Seam Welding Machines (Nonportable) 415.3 Portable Welding Machines ... . .. . 425.4 Flash Welding Equi7Jment .. 425.5 Hazards and Precautions . . . . . .. 435.6 Maintenance. '" . . . . . 43

6. Fire Prevention and Protection6.1 Basic Precautions6.2 Special Precautions6.3 Welding or Cutting Containers6.4 Sprinkler Protection6.5 Confined Spaces

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.. 43....... 43

4345... 45

...... 45


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7. Protection of P.rsonnel ................ ............................... .................... 467.1 General ................................................................................ 467.2 Eye Protection .................................................................. 467.3 Protective Clothing ......................................................... 497.4 Work in Confined Spaces .................................................. 508. Health Protection and Ventilation.......................... .......................... 518.1 General ................................................................................ 518.2 Ventilation for General Welding and Cutting ............... 53

B.3 Local E'thaust Hoods and Booths ................................. 538.4 Ventilation in Confined Spaces .. ............................. 548.5 Fluorine Compounds ...................................................... 558.6 Zinc .................................................................................. 558.7 Lead .. ................................................................................... 558.8 Beryllium .... ........................................................... 568.9 Cadmium.............................................. ........ ........ 568.10 Merour" ................................................................ , ........ 56B.ll Other Materials of Toxic Significance .. 568.12 Brazing Atmospheres . ....................................... 57B.13 Cleaning Compounds ....... .... . . . ... .. . ..... .. 578.14 Cutting of Stainless Steels.. .... . .......... 588.15 Medical ContTol and First Aid. .. ........... 58

9. Industrial Applications ................. ..... .... . .. .. .. . . ...... 58Part I - Construction Industry . . ...... 58A. General...................... .......... .. . ......... . ................ 58B. General Maintenance Welding and C u t t i n ~ Operations 59C. Earth Moving and Grading Equipment -Operation and Maintenance ..D. Fire Protection and Prevention .E. Demolition ....... ......................... .F. Concrete Construction and "Ma.


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Foreword

During World War II, the increased industrial activity brought on bywar production emphasized the need for preserving manpower and avoiding lost-time accidents. Since the existence of proper safety regulationsand their use are the first and most important steps in any program ofsafety and accident prevention, and since welding during World War IIwas too often done by inexperienced and casually trained personnel, theneed for complete infonnation on safety seemed most pressing. Accordingly, in June 1943, the AMERICAN WELDING SOCIETY, the InternationalAcetylene Association, the National Electrical Manufacturers Associationand the Division of Labor Standards of the U. S. Department of Laborrequested the American Standards Association (now United States ofAmerica Standards Institute) to initiate the development of an AmericanWar Standard for Safety in Electric and Gas Welding and Cutting Operations. This American War Standard was published in 1944 and was wellreceived by ~ d u s t r y . In fact, the American War Standard met .such a realneed, that it was deemed desirable to initiate a Sectional Committee toprepare an American Standard (now called USA Standards) on the samesubject to supersede the American War Standard, and provide safetyrecommendations for welding and cutting operations which were applicable to nonnal peacetime production.To accomplish this, ASA Sectional Committee Z49, Safety in Electricand Gas Welding and Cutting Operations (now USA Standards Committee Z49, Safety in Welding and Cutting) was organized in March1946 under the sponsorship of the AMERICAN WELDING SOCIETY. ThisCommittee as organized comprises a wide representation of users andsuppliers of welding equipment and welded products, insurance companies, governmental bodies and other organizations interested in weldingor cutting. Preparation of this Standard was through meetings of theCommittee and its subcommittees and through correspondence. A draftAmerican Standard was first prepared and this was then circulated widelythrough industry for comment. As the final step all comments and suggestions received were then carefully reviewed. This American Standard wasfirst issued in 1950; the present (third) edition was published in 1968.This Standard is presented in the hope that adherence to the safetyrequirements contained herein will result in the elimination of possiblehazards due to welding and cutting; hence, the elimination of avoidableaccidents and property damage.The current local, municipal, state, and federal regulations relativeto welding, cutting and allied processes shall be observed.Comments or questions concerning this Standard will be most welcome. They should be sent to S ~ c r e t a r y , USA Standards Committee Z49,AMEluCAN WELDING SOCIETY, 345 East 47th Street. New York, N. Y. 10017.

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Citation

Where safety oflicials desire that welding be performed in accor.d-anee with the ptov;'Wons of this Standnrd, but do not wish to include thisSfandllrd in its entirety in their own stanikz.rd, the jollotdnp, citation maybe inserted in their standard:

SAFETY IN WELDING AND CUnlNG"The operation and maintenance of welding and cutting equipmentshall confonn to the provisions of the USA Standard Z49.1, Safety inWelding and Cutting"

AU persons or organizatiOns wishing to republish this material inwhole or in part shall consult with the AMERICAN WELDING SOCIETY forp8f'111ission..

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- - - _ ._---Non:: By publication of this Standard, thll American Wl'lding Sr)cicty dut's nul insllwanyone utilizing the Standard against Unhi/ity arising from tIl(' liS!' (If Sill'll

Standllrd. A publication of a Stnndllrd hy the Amt'rican Welding Sot'il'ty rI()(,Snot carry with it the right to make, use or sell any patented ihms. Euch pro-spective u . ~ e r should make an independent investigation.

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Safety in Welding and Cutting I 1

Safety in Weldingand Cutting

1. Scope1.1 This standard is for the protection of persons from injury and illnessand the protection of property (including equipment) from damage byfire and other causes arising from welding and cutting.1.2 Specific provisions are included for gas welding, shielded metal-arcwelding, submerged arc welding, gas shielded-arc welding, hrazinf!; andresistance welding. However, the requirements of this stam.1ard aregenerally applicable to the other welding proc.'esses shown in tIlt' AWSMaster Chart of Welding Processes, A3.1-61.1.3 No attempt has been made to include all particular hazards whichmay be inherent when welding and cutting equipment is lIsed in specialindustries.

2. Definitions2.1 Shall is used to indicate provisions which are mandatory.2.2 Should 'or it is recommended is used to indicate provisions whichare not mandatory but which are pointed out here as recommended goodpractices.


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21 Safety in Welding and Cutting

2.3 The words approt)ed or approval as used in this standard meanacceptable to the authority having jurisdiction.NOTE: For the purpose of this standard it is recommended that the authorityhaving jurisdiction accept welding and cutting equipment that has beentested and listedby Underwriters' Laboratories, Inc., C h i c n ~ o , nnd/orby Factory Mutual Engineering Division, Norwood, Mass.

2.4 The tenns welder and welding operator as used herein are intendedto designate any operator of electric or gas welding and cutting equipment.2.5 All other welding tenns used herein are in accordance with AWSDefinitions - Welding and Cutting, A3.0-61.

3. Installation and Operation ofOxygen-Fuel Gas Systems forWelding and Cuffing3.1 GENIRAL PROVISIONS3.1.1 Mixtures of fuel gases and air or oxygen may be explosive andshall be guarded against. No device or attachment facilitating or permitting mixtures of air or oxygen with flammable gases prior to consumption,except at the burner or in a standard torch, shall be al10wed unlessapproved for the purpose.3.1.2 Under no condition shall acetylene be generated, piped (exceptin approved cylinder manifolds) or utilized at a pressure in excess of 15psi gage pressure or 30 psi absolute pressure. (The 30 psi absolute pressure limit is intended to prevent unsafe use of acetylene in pressurizedchambers such as caissons, underground excavations or tunnel construction.) This requirement is not intended to apply to storage of acetylenedissolved in a suitable solvent in cylinders manufactured and maintainedaccording to Interstate Commerce Commission requirements, or to acetylene for chemical use, The use of liquid acetylene shan be prohibited.

-LISTED: Equipment or materials included in a list published by n nationlllly r e c o ~ -nized testing laboratory that maintains periodic inspection of produ(.tion ()f l i s t ( ~ d equipment or materials, and whose listing stutes t>ith('r thnt thc cquipmf'nt or matt'linl mcl'tsnationally recognized standards or has been tllstt'd and found suitable for tlS(' in a Spl'ci.6ed manner.


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Safety in Welding and Cutting 13

3.1.3 Only approved apparatus (see Par. 2.3) such as torches, regulatorsor pressure-reducing valves, acetylene generators and manifolds shall beused.3.1.4 Worlanen in charge of the oxygen or fuel-gas supply equipment,including generators, and oxygen or fuel-gas distribution piping systemsshall be instructed and judged competent by their employers for thisimportant work before being left in charge. Rules and instructions covering the operation and maintenance of oxygen or fuel-gas supply equipment, including generators, and oxygen or fuel-gas distribution pipingsystems shall be readily available.

3.2 CYLINDIRS AND CONTAINERS3.2.1 Approval and Marking3.2.1.1 All portable cylinders used for the storage and shipment ofcompressed gases shall be constructed and maintained in accordance withthe regulations of the Interstate Commerce Commission. 03.2.1.2 Compressed gas cylinders shall be legibly marked, for the purpose of identifying the gas content, with either the chemical or the tradename of the gas. Such marking shall be by means of stenciling, stampingor labeling, and shall not be readily removable. Whenever practical, themarking shall be located on the shoulder of the cylinder. This methodconfonns to the Method for Marking Portable Compressed Ga.s Con-tainers to Identify the Material Contained, USA Standard Z48.1-1954.3.2.1.3 Compressed gas cylinders shall be equipped with connectionscomplying with the Compressed Gas Cylincler Value Outlet aru] InletConnections, USA Standard B57.1-1965.3.2.1.4 All cylinders with a water weight capacity of over 30 lbs. shallbe equipped with means of connecting a valve protection cap or with acollar or recess to pr'?tect the valve.3.2.2 Storage of Cylinders - General3.2.2.1 Cylinders shall be kept away from radiators and other sourcesof heat.

-In Canada, the speCifications and regulationli of the Board of Transport Commissioners for Canada apply.


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4 ISafety in Welding and Cutting3.2.2.2 Inside of buildings, cylinders shall be stored in a well-protected,well-ventilated, dry location, at least 20 feet from highly combustiblematerials such as oil or excelsior. Cylinders should be stored in definitelyassigned places away from elevators, stairs or gangways. Assigned storagespaces shall be located where cylinders will not be knocked over or damaged by passing or falling objects, or subject to tampering by unauthorized persons. Cylinders shall not be kept in unventilated enclosures suchas lockers and cupboards.3.2.2.3 Full cylinders of oxygen and fuel-gas should he used in rotationas received from the supplier.3.2.2.4 Empty cylinders shall have their valves closed.3.2.2.5 Valve protection caps, where cylinder is designed to accept acap, shall always be in place, hand-tight, except when cylinders are in llseor connected for use.3.2.3 Fuel.Gas Cylinder Storage3.2.3.1 Inside a huilding, cylinders, except those in actual use orattached ready for use, shall be limited to a total gas capacity of 2000cubic feet or 300 pounds of liquefied petroleum gas. In large, well-vmtilated, one-story buildings, exceptions to this rule may he granted by theproper authorities.3.2.3.2 For storage in excess of 2000 cuhic: feet total gas capacity ofcylinders or .'300 pounds of liquefied petroleum ~ a s . a separate room or.compartment (.'onfonning to the requirements spl'dlicc1 in 3.6.6.l11 and3.6.6.li shall he provided, or cylinders shall he kept outside' or in a specialbuilding. Special h l 1 i 1 d i n ~ s . rooms or compartments shnllhavl! no opt'nflame for heatinJ,!; or lip;htinJ,!; and shall he w(,H-V


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3.2.4.2 Oxygen cylinders stored in outside generator houses shall beseparated from the generator or carbide storage rooms by a noncombustible partition having a fire-resistance rating of at least one hour. Thispartition shall be without openings and shall be gas-tight.3.2.4.3 Oxygen cylinders in storage shall be separated from fuel-gascylinders or combustible materials (especially oil or grease), a minimumdistance of 20 feet or by a noncombustible barrier at least 5 feet highhaving a nre-resistance rating of at least 1h hour.3.2.4.4 Where a liquid oxygen system is to be used to supply gaseousoxygen for welding or cutting and the system has a storage capacity of(a) more than 13,000 cubic feet of oxygen (measured at 14.7 psia and70F), connected in service or ready for service, or (b) more than 25,000cubic feet of oxygen (measured at 14.7 psia and 70F), i n c 1 u d i n ~ unconnected reserves on hand at the site, it shall comply with the provisions ofthe Standard for Bulk Oxygen Systems at Consumer Sites, NFPA No. 566.3.2.5 Operating Procedures3.2.5.1 Oxygen Cylinders3.2.5.1a The following precautions shall be observed:Always refer to oxygen by its proper name oxygen and not, for example,by the word air. Oxygen will not burn, but supports and accelt'rates combustion, and will cause oil and other similar materials to hnrn with greatintensity. Oil or grease in the presence of o x y ~ e n may ignite and h11mviolently.

WARNINGA serious accident may easily result if oxygen is l /"\ 'ccllIS a .\/l!J ...titutefor compressed air, Never use oxygen in 1met/matic tools, i1l oil pre-heatin:! burners, to .nart internal combustion ! n g i t l c . ~ , to biOte Ollt pipelines, to dust clothing or work, to cl'(Jate p"essw'c 01 ' f{)r v e 1 ~ t i l n t i ( ) n .

3.2.5.1 b Cylinders, cylinder valves, c o u p l i n ~ s , ngnlators, hose andapparatus shall be kept free from oily or greasy sl1hstances. Oxygencylinders or apparatus shall not 1)(\ handled with oily hands or glove's. Ajet of oxygen must never be Permitted to strike an oily surfucc, ~ r e a s yclothes, or enter a fuel oil or other storage tank.3.2.5.2 F u e l . G ~ s Cylinders3.2.5.2a Fuel gases shall be called by their proper names and not bythe word gas.


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6 ISafety in Welding and Cutting3.2.5.3 Handling - General3.2.5.3a When transporting cylinders by a crane or derrick, a cradle,boat or suitable platfonn shall be 1,lsed. Slings or electric magnets shannot be used for this purpose. Valve-protection caps, where cylind(;r isdesigned to accept a Cap, shall always be in place.3.2.5.3b Cylinders should be moved by tilting and rolling them on theirbottom edges. Dragging and sliding should ht avoided. When cylindt'rsare transported by vehicle they should be secured ;n position. Cylindersshall not be dropped or struck or pemitted to strike each other violently.3.2.5.3c Valve-protection caps shall not be. used for lifting cylindersfrom one vertical position to another. Bars shall not be llsed under valvesor valve-protection caps to pry cylinders loose when frozen to the groundor otherwise fixed; the use of wann (not boiling) water is n(.'()Jl)llllnded.Valve-protection caps are designed to protect cylinder valves fromdamage. Before raising cylinders provided with valve-protection capsfrom a horizontal to a vertical position, the cap should he properly inplace. The cap should be turned clockwise to see that it is hand-tight.3.2.5.3d A suitable cylinder truck, chain or steadying devic(' should htused to keep cylinders from being knocked over whilt' in tlst'.3.2.5.3e Unless cylinders are secured on II special truck, r ( ' ~ u l a t ( ) r s shallbe removed and valve-protection cups, when pTovidl'u for, shll1l1w put illplace before cylinders llre moved.3.2.5.3f Cylinders not having fixt'd hand wheels shall have keys,handles or nonadjustable wrcnchts on valve' stems while thts{' cylilldt'TSare in service. In multiple cylinder installations only Ollt' key or handl( isrequired for each manifold.3.2.5.3g Cylinder valves shall be closed before moving cylindl'Ts.3.2.5.3h Cylinder valves shall be closed when work is finished.3.2.5.31 Valves of empty cylinders shall he closed.3.2.5.3i Cylinders shall he kept far enough away from th' actual welding or cutting operation so that sparks, hot slag or Harne will lIot f('achthem, or nre-resistant shields shall he provided.


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Safety in Welding and Cutting I 73.2.5.3k Cylinders shall not be placed where they might become partof an electric circuit. Contacts with third rails, trolley wires, etc., shall beavoided. Cylinders shall be kept !lway from radiators, piping systems, layout tables, etc., that may be used for grounding electric circuits such asfor arc welding machines. Any practice such as the tapping of an electrode against a cylinder to strike an arc shall be prohibited.3.2.5.31 Cylinders shall never be used as rollers ()r supports, whetherfull or empty.3.2.5.3m The numbers and markings stamped into cylinders shall notbe tampered with. (Such tampering is illegal.)3.2.5.3n Empty cylinders should be marked "empty" or "MT,". segregated from full cylinders and promptly returned to the supplier withvalve-protection caps in place (See 3.2.5.3a above). All valws shall beclosed.3.2.5.30 No person, other than the gas supplier, shall attempt to mixgases in a cylinder. No one, except the owner of the cylinder or personauthorized by him, shall refill a cylinder.3.2.5.3p No one shall tamper with safety devices in cylinders or valv(s.3.2.5.4 Use - Oxygen Cylinders3.2.5.4a Cylinders shall not be dropped or otherwise roughly handled.3.2.5.4b Unless connected to a manifold, oxygen from a cylindpr shallnot be used without first attaching an oxygen regulator to tht' cylindervalve. Before connecting the regulator to the cylinder valve, the valwshall be opened slightly for an instant and then dosed. (This action isgenerally termed cracking and is intended to clear the valve of dust ordirt that otherwise might enter the regulator.) Always stanel to one sideof the outlet when opening the cylinder valve.3.2.5.4c A hammer or wrench shaH not he used to open eyHnder valves.If valves cannot be opened by hand, the supplier shall he notified.3.2.5.4cI Cylinder valves shall not he tampered with nor should anyattempt be made to repair them. If trouhle is experienced, the suppliershould be sent a report promptly indicating the character of the trouhleand the cylinder's serial numher. Supplier's instructions as to its disposition shall be followed.


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8 ISafety in Welding and Cutting3.2.5.48 After a regulator is attached, an oxygen cylinder valve shouldbe opened slightly at first so that the r e ~ u l a t o r c y l i n d e r ~ p r e s s u r e ~ g a g ehand moves up slowly; then the valve can be opened all the way. I f thehigh pressure is suddenly released, i t is liable to damage the regulator andpressure gages. Stand to one side of the regulator and not in front of theglass-covered gage faces when opening the cylinder valve.3.2.5.4f When the oxygen cylinder is in use, the valve should be openedfully in order to prevent leakage aronnd tlw valve stem. Complete removal of the stem from a d i a p h r a g m ~ t y p e cylinder valve shall be avoided.3.2.5.5 Use - Fuel.Ga5 Cylinder53.2.5.5a Fuel-gas cylinders shall be placed with valve end lip wheneverthey are in use. Liquefied gases shall be stored and s h i p p ~ ' d with thevalve end up.3.2.5.5b Cylinders shall be handled carefully. Rough handling, knocks,or falls are liahle to damage the cylimler, valve or safety devices an dcause leakage.3.2.5.5c Before connecting a regulator to a cylind(r valy{', the valv('shall he opened slightly and closed imnlt'diat(ly. (This a


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Safety in Welding and Cutting I 93.2.5.59 I f a leak should develop at a fuse plug or other saf(,ty device,the cylinder should he removed to the out-of-doors well away from anysource of ignition; the cylinder valve should be opened slightly and thefuel-gas allowed to escape slowly.3.2.5.5h A warning should be placed near cylinders having leaking fuseplugs or other leaking safety devices not to approach them with a lightedCigarette or other source of ignition. Such cylinders should he plainlytagged; the supplier should be promptly notified an d his instructionsfollowed as to their return.3.2.5.5i Safety devices shaU not he tampered with.3.2.5.5i F u e l ~ g a s shall never he lIlied from cylinders through torches orother devices equiped with shut-off valves without nducing thp. pressurethrough a suitahle regulator attached to th e cylinder valve or manifold.3.2.5.5k The cylinder valvc shaH always he' opened s l o w l y ~3.2.5.51 An acetylene cylinder valve shall no t 1)(' opened more thanIV!! turns of the spindle, and preferahly no more than ;14 of a tum.3.2.5.Sm Where II special wrench is re'luin'd it shall 1)(' ld t in positionon the stem of the valve while the l'ylindl'T is in l lS! ' so that the ful'l-gasflow can he quickly turned off in case of enwrgl'ncy. In thl' casp of manifolded or (.'oupled cylinders at least one slleh wrench shall always ht>'Ivailahle for imrm,diat(' lise.3.3 MANIFOLDING OF CYLINDERS3.3.1 Fuel-Gas Manifolds3.3.1.1 Manifolds shall hl' approVt'cl ('itlwl' s('parnh'ly for (':teh component part or as an assembled unit.3.3.1.2 Exc


19/78

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10 ISafety in Welding and Cutting3.3.1.4 Separate manifold buildings or rooms may also be used for thestorage of drums of calcium carbide and cylinders containing fuel gasesas provided in 3.2.3. Such buildings or rooms shall have no open flamesfor heating or lighting and shall be well-ventilated.3.3.1.5 High-pressure fuel-gas manifolds shall be provided with approved pressure regulating devices.3.3.2 High.Pressure Oxygen Manifolds (for use with cylindershaving an ICC .ervlce pressure above 200 psig)3.3.2.1 Manifolds shall be approved either separately for each com-ponent part or as an assembled unit.3.3.2.2 Oxygen manifolds shall not be located in an acetylene generatorroom. Oxygen manifolds shall be separated from fuel-gas cylinders orcombustible materials (especially oil or grease), a minimum distant'l' of 20feet or by a noncombustible barrier at least 5 feet high having .a fireresistance rating of at least % hour.3.3.2.3 Except as provided in 3.3.2.4, oxygen cylinders cOOlwcted toone manifold shall be limited to a total gas capacity of 6000 cubic fl'et.More than one such manifold with connected cylinders may he locatedin the same room provided the manifolds are at least 50 feet apart orseparated by a noncombustible barrier at least 5 ft. high having a fireresistance rating of at least Y:! hour.3.3.2.4 An oxygen manifold, to which cylinders h a v i n ~ an a g g l ' q ~ a t l 'capacity of more than 6000 cuhic feet of oxygen UT(' conn((.'tcd, should Ill'located outdoors or in a separate non-combustible h u i l d i n ~ , Such a mlluifold, if located inside a building h t \ v i n ~ other occupancy, shall hl' locatedin a separate room of nonc..'Ombllstihle construction having a firl'-rC'sishl1lcl'rating of at least % hour or in an area with no


20/78

Safety ill Welding and Cutting \1 1

3.3.2.6 High-pressure oxygen manifolds shall he provided with approved pressure-regulating devices.3.3.3. Low-Pressure Oxygen Manifolds (for use with cylinders

having an ICC .. vice pressure not exceeding 200 psig).3.3.3.1 Manifolds shall be of substantial construction suitable for usewith oxygen at a pressure of 250 psig. They shall have a minimum bursting pressure of lOOO psig and shall he protected hy a safety relief devicl'which will relieve at a maximum pressure of 500 psig.

NOTE: ICC-4L200 cylinders haw . ~ a f e t y dl'vil'l':; which fl'!iI'V!" at a maximumpressure of 250 psiS (o r 235 PShl if VlIl'llllm inslllatioll is I1SI'II),

3.3.3.2 Hose and hose connections suhject to cylinder pressure shallcomply with 3.5.5. Hose shall have a minimum hursting pressure of 1000psig.3.3.3.3 The assembled manifold including leads shall 1)(' testNI andproven gas-tight at a pressure of 300 psig. The fluid used for testingoxygen manifolds shall be oil-free and not comhustible.3.3.3.4 The location of manifolds shall comply with 3.3.2.2, 3.3.2.3,3.3.2.4, and 3.3.2.5.3.3.3.5 The follOWing sign shall be conspicuollsly posted at each manifold:

LOW-PRESSURE MANIFOLD -- ]DO NOT CONNECT HIGH-PRESSURE CYLINDEHS IMAXIMUM P R E ~ S ~ ~ ~ . E - = - _ ~ O PSIC . i

3.3.4 Portable Outlet Headers3.3.4.1 The tenn portable outlet header is USed to mean any assemhlyof valves and c.'onnections used for service outlet purposes, which is connected to the pemlancnt service p i p i n ~ system hy means of hose or othernonrigid conductors. Devices of this nature arc commonly IIsed at piersamI drydocks in shipyards wllt're the service p i p j n ~ cannot 1)(' locat(dclose enough to tho work to provitl


21/78

. - - - - - ~ - - - - - - .. - - - - - - . ~ - - - - - - - - - - - - - - - - - -

12 ISafety in Welding and Cutting3.3.4.4 Hose and hose connections used for connecting the portableoutlet header to the service piping shall comply with Section 3.5.5.3.3.4.5 Master shutoff valves for both oxygen and fuel-gas shall be.provided at the entry end of the portable outlet header.3.3.4.6 Portable outlet headers for fuel-gas service shall be providedwith an approved hydraulic back-pressure valve installed at the inlet andpreceding the service outlets, unless an approvecl pressure-reducingregulator, an approved back-flow check valve, or an approved hydraulicback-pressure valve is installed at each outlet. Outlets provided onheaders for oxygen service may be fitted for use with pressure-reducingregulators or for direct hose connection.3.3.4.7 Each service outlet on portable outlet headers shall be providedwith a valve assembly that includes a detachable outlet seal cap, chainedor otherwise uttached to the body of the valve.3.3.4.8 Materials and fabrication procedures for pc)rtahle outlet hendersshall comply with Sections 3.4.1, 3.4.2 and 3..1.5.3.3.4.9 Portable outlet headers shall he provided with frames whichwill support the equipment securely in the correct operating position andprotect them from damage durinp; handling and operation.3.3.5 Manifold Operating Procedures3.3.5.1 Cylinder manifolds shall he installed IInder tilt' sllpervisioTi ofsomeone familiar with the proper practiee:-; with Tl'fl 'Wllt'(' to thdr COIl-struction and use.3.3.5.2 All component parts used in the methods of manifolding described in 3.3.5.9 shall be approved as to materials. design and construction either separately or as an assemhled unit.3.3.5.3 AU manifolds and parts used in methods of manifolding shallbe used only for the gas or gases for which they are appr()wd.3.3.5.4 When acetylene cylinders are coupled, approved flash arrtlstcrsshall be installed between each cylinder and the coupler hlock. For outdoor use only, and where the number of cylinders coupled dOl'S notexceed 3, one Hash arrester installed between the coupler hlock and rC!,"Ilator is acceptable.3.3.5.5 Each fuel-gas cylinder lead should he provided with H backfl()wcheck valve.


22/78


3.3.5.6 The aggregate capacity of fuel-gas cylinders connected to aportable manifold inside a building shall flot exceed 3000 cubic ft:'et ofgas.3.3.5.7 Acetylene and liquefied fuel-gas cylinders shall be manifoldedin a vertical position.3.3.5.8 The pressure in the gas cylinders connected to and dischargedsimultaneously through a common manifold shall be approximatdy


23/78

14 ISafety in Welding and Cutting

(2) Copper tubing shall be Types K or L in accordance with theStandard Specification for Seamless C;opper Water Tube, ASTMB88-66a.3.4.1.1b Piping shall be steel, wrought iron, brass or copper pipe, orseamless copper, brass or stainless steel tubing, except as provided in3.4.1.2 ~ d 3.4.1.3.3.4.1.2 Oxygen Piping3.4.1.2a Oxygen piping and fittings at pressures in excess of 700 psig.shall be stainless steel or copper alloys.3.4.1.2b Hose connections and hose complying with Section 3.5.5 maybe used to connect the outlet of a manifold pressure regulator to pipingproviding the working pressure of the piping is 250 psig or less and thelength of the hose does not exceed 5 feet. Hose shall have a minimumbursting pressure of 1000 psig.3.4.1.2c When oxygen is supplied to a service piping system from 11low-pressure oxygen manifold without an intervening pressure regulating;device, the piping system shall have a minimum design pressure of 250psig. A pressure regulating device shall be used at each station outletwhen the connected equipment is for use at pressures less than 250 psig.3.4.1.3 Piping for Acetylene and Acetylenic Compounds3.4.1.3a Piping for acetylene or acetylenic c.:ompollnds shall he step] orwrought iron.3.4.1.3b Unalloyed copper shall not be used for ucetyletw or acetyi('niccompounds except in listed eCjlliptnt'nt.3.4.2 Piping Joints3.4.2.1 Joints in steel or w r ( ) u ~ h t iron p i p i n ~ shall he wl'lded, threadedor Hanged. Fittings, such as clls,tcC's, couplings and t 1 n i ( ) n s ~ may Iwrolled, forged or cast steel, malleahle iron or nodular iron. Gray or whitecast iron fittings nre prohibited.3.4.2.2 Joints in brass or coppel" pipe shall be welded, hrazl'd, thn'lHlt,dor flanged. I f of the socket type, they shall he hrazml with silwr-hrazingalloy or similar high melting point (not Jess than I;()O"F) filler lIH'tal.3.4.2.3 Joints in seamless copper, hrass, or stainll'ss sted tllhing shallbe approved gas tubing fittings or the joints shull he hrazed. If of thesocket type, they shall be brazed with silver-brazing alloy or similar highmelting point (not less than 800F) filJer metal.


24/78

- - - - - . - - - - ~ - - - - ~ - - - -------_ .__ ._----------------_ ._--- - - - - - - - - - - - ~ - - - - - -_.__ -- - - - - - - - . - - - - - - - - . - ~

Safety in Weldinf;! and Cuttin#, I 153.4.2.4 Threaded connections in oxygen plpmg should be tinned ormade up with litharge and glycerine (litharge and water are sometimesused for service pressures over 300 psi.) or other jOint compounds approved for oxygen service, applied to the externally threaded portion.3.4.3 Installation3.4.3.1 Distribution lines shall be installed and maintained in a safeoperating condition.3.4.3.2 Piping located inside or outside of buildinJ,!;s may be placedabove or below ground. All piping shall be run as directly as practicahle,protected against physical damage, proper allowance heing made forexpansion and contraction, jarring and vibration. Pipe laid undergroundin earth shall be located below the frost line and protected againstcorrosion. After assembly, piping shall be thoroughly blown Ollt with air,nitrogen or carbon dioxide to remove foreign materials. For oxygl'n piping, only oil-free air, oil-free nitrogen or oil-free carhon dioxide shall heused.3.4.3.3 Only piping which has been welded or brazed shall he installedin tunnels, trenches or ducts. Shut-off valves shall Ill' located olltside suchconduits. Oxygen piping may be placed in the same tunnel. trench orduct with fuel-gas pipe lines, provided there is good natural or forc{'dventilation.3.4.3.4 Low points in piping carrying moist gas shl\l1 he dmincd intodrip pots constructed so as to permit pumpinJ,!; or draininJ,!; Ollt thecondensate at necessary intervals. Drain valves shall he illstalll'(\ for thispurpose having outlets nonnally closed with screw caps or plugs. Noopen-end valves or petcocks shall he used, except that in drips locatedout-of-doors, underground, and not readily accessible, valvt's may 1)('used at such points i f they are equipped with means to secltre them illthe closed position. Pipes leading to the surface of the p;round shall 1)('cased or jacketed where necessary to prevent loosening or hnaking.3.4.3.5 Gas cocks or valves shall he prOVided for all huildillJ,!;s at pointswhere they will be readily accessihle for shuttiTlJ,!; off the gas supply tothese buildings in any emergency. Underground valve hoxes or manholesshould be avoided wherever possihle. There shall also he providml ashut-off valve in the discharge line from the J,!;enmator, J,!;as holder, manifold or other source of supply.3.4.3.6 Shut-off valves shall not he installed in safety relief lines in sucha manner that the safety relief device can be rendered ineffective.


25/78

16 ! Safety in Welding and Cutting

3.4.3.7 Fittings and lengths of pipe shall be examined illt{'rnallyBEFORE ASSEMBLY and, if necessary, freed from scale or dirt. Oxygellpiping an d fittings shall be washed out witl) a suitabl(, sollltion whichwill effectively remove grease and dirt bu t will not react with ( ) x y ~ c n .

Non:: Hot wlitcr NOJUtiOIlS of caustic ~ ( ) d a or t r i ~ ( ) d i l 1 m p l l 1 l ~ p l H l t l ' liT(' dTI'l'liv('cleaning lIgcnts for this purpose.3.4.3.8 Piping shall be thoroughly hlov.!ll ou t after ass('mhly to rellloveforeign materials, Fo r oxygen p i p i n ~ , oilfree air, o i l - f r e ( ~ nitrogen or oilfree carbon dioxide shall be used. For other piping, air or int'rt !1:as maybe used.3.4.3.9 When flammable gas lines or other parts of l'quipllwnt art' 1wingpurged of air or gas, open lights or other sources of ignitioll slUlIl Jlot hepermitted near uncapped openings.3.4.3.10 The surface temperature of acetylenc pipe lilll's should Ilot heallowed to exceed 130F.3.4.3.11 No welding or eutting shall 1w lwrfonm'll 011 lUI t t e l ' t y l l ~ I l l ' oroxygen pipe line, including the attachment of h a l l ~ l ' r S (>r SlIpports, untilthe line has been purged. Ollly oil-free air, oil-free nitJ'Ogl'lI or oilfreecarbon dioxide shall be used to purp;e oxygen l i n e s ~3.4.4 Painting and Signs3.4.4.1 Underground pipe und tubing and outdoor ferrous pipl' l lmltubing shall he covered or painted \vith a suitable material for prott'CtiOIlagainst corrosion.3.4.4.2 Ahoveground piping systems shall 1)(' lllarJ..:(d ill Ht'("onlant'l'with the Scheme for the Idl'lIlifictlticlII of Piping SUS{C'TIIS, liSA StandardA13.1-1956,3.4.4.3 Statioll ontlets shall \)(' Illarkl,d tt l i l l l l i e a t < ~ tIl(' IHl l l l l ' of Ihl! ,.;tts.3.4.4.4 Signs clearly ('stahlishillg thl' locatiou a1ld identity of Sl'etiollshutoff valves should he provided.3.4.5 Testing3.4.5.1 P i p i n ~ systems shall be t{'sted and pro,,{!d gas-tight at OIw-andone-half times the maximum operating p n ' s s l 1 n ~ , ~ . l 1 I d shall hc! thoJ'OlIglllypurged of air before \wing placed in scrvice. Th e matt'rial IISI't! for h'st-in g oxygen lines shall he oil-free an d nOllcomJ)1Istihle. Flallll'S shall llothe used to detect leaks,3.4.5.2 When flammahle ~ l \ S lines or other parts of eqlliplIll'lIt


26/78


3.5 PROTECTIVE EQUIPMENT, HOSE, AND REGULATORS3.5.1 General3.5.1.1 Equipment shall be installed and used only in the service forwhich it is approved and as recommended by the manufacturer.3.S.2 Pressure Relief for Service Piping Systems3.5.2.1 Service piping systems shall he protected by p r t ' S S U f ( . ~ relief tll'vices set to function at not more than the design pressure of the systemsand discharging upwards to a safe location.3.5.3 Piping Protective Equipment3.5.3.1 The fuel-gas and oxygen piping systems, including portahl(,outlet headers shall incorporate the protective equipment shown, inFigures 1, 2, or 3.3.5.3.1 a When only a portion of a fuel-gas system is to he us('d withoxygen. only that portion need comply with 3.5.3.1.3.5.3.2 Approved protective equipment (designated P . ill F i ~ I I r < s 1. 2& 3) shall be installed in fuel-gas piping to prevent:(1) backBow of oxygen into the fuel-gas supply system:(2) passage of a flash hack into the f u e l - ~ a s supply system: and

(3) excessive back pressure of oxygen in the fud-gas supply system.NOTE: The three functions of th" protl't'tiVl' !'I\uipml'nt may hI' l'nmhilwt! illone device or may be provitll'll hy sf'paTah- ( 1 ( ~ v i l . ' l ' S , .

3.5.3.2a The protective eqwpment shall he lomtl.'d in the main supplyline, as in Figure 1; or at the head of each branch lillt', as in Figure 2; orat each location where fuel-gas is withdrawn, as ill F i ~ u r c :3. When'branch lines are of 2-inch pipe sir.e or larger or of subShlutial length,protective equipment (designated as P f.) shall be locatNI as shown ineither Fig. 2 or Fig. 3.3.5.3.2b Backflow protection shall be provided by an approved cll'vie('that will prevent oxygen from flowing into the fud-gas system or filI.'Ifrom flowing into the oxyp;cn system (See S." Figs. 1 & 2).3.5.3.2c Flash-hack protection shall be provided hy an approved devicethat will prevent flame from passing into the fuel-gas system.3.5.3.2d B a c k ~ p r e s s u r e protection shall be provided hy an approvedpressure-relief device set at a pressure not greater than the pressure rating of the bacldlow or the Bash-back protection device, whichever is


27/78

18 1 Safety in Welding and Gutting

lower. The pressure-relief device shall be located on the downstream sideof the backHow and flash-back protection devic.-es. The vent from thepressure-relief device shall he at least as large as the relief device inletand shall be installed without low points that may collect moistmc. I flow points are unavoidable, drip pots with drains closed with screw.plugs or caps shall be installed at the low points. The vent terminus shallnot endanger personnel or property through gas discharge; shall helocated away from ignition sources; and shall tenninate in a hood orbend.3.5.3.3 If pipeline protective equipment incorporates a liquid, thl'liquid level shall be maintained, and a sWtable antifreeze may he llst'd toprevent freezing.

FUELUELGA S OXYGEN GAS

TO TORCHOR MACHI NE

Figure 1LEGEND

FUELOXYGEN GAS

TO TORCHOR MACHINE

FigUre 2

OXYGEN

TO TORCHOR MACHINE

F!ture 3

P, - ProrecdYe equipment In fuel a . plplDav, - Fueill.' ltatlon outlet ftlftVo - Osyllen .Itatfon outlet ft lf t

8. . - Backflow pre,eDdoll de9ice(a)at fuel au aUtioD outletSo - Back80w pre'NDtion dmce(a)a t O:l)'iell ltadoD outlet

Figures I, 2, & :} - Schematic Arrans.wm(!nt:; of Pipins,: and SlatillJlOutlet Protective Equipment. (Sl'f' Sl'ctions 3.5.3. and 3.5.4)


28/78

Safety in Welding and C IItting ! 193.5.3.4 Fuel-gas for use with equipment no t requiring ( ) X y . ~ l ' T I ~ h a n hI'withdrawn upstream of the piping protective devices.3.5.3.5 Where a compressor or booster pump is used in n fuel-gussystem requiring oxygen an d where this fuel-gas is withdrawn from nsource that also supplies !l system not requiring oxygen, the lattl'r $y!;temshould incorporate a check valve to prevent possible backflow.3.5.4 Station Outlet Protective Equipment3.5.4.1 A check valve, pressure regulator, hydralllic seal, or comhina-tion of these devices shall be provided at each station outlet. includingthose on portahle headers, to prevent backHow, a!; shown in Figur('s 1.2,and 3 and deSignated as S . an d So.3.5.4.2 When approved pipeline protective I"qllipment (dcsi.l.!;natrd P,,,)is located at the station outlet as in Figure 3, no additional cht'ck valv(',pressure regulator, or hydraulic seal is required.3.5.4.3 A shutoff valve (designated Vf' and VI)) shall be installed at eachstation outlet and shall be located on the upstream side of other stationoutlet equipment.3.5.4.4 If the station outlet is equipped with a detachahl!' f{'glllator.the outlet shall tenninate in a union connection that complics with tIl('Regulator Connection Standards, 1958, Compressed Gas Association.3.5.4.5 If the station outlet is connect('(1 directly to a host, tIl


29/78

20 [ Safety in Welding and Cutting

3.5.5 Hose and Hose Connections3.5.5. J Hose for oxy-fueI gas serviCi:.' shan comply with the SlJl!cificationfor Rubber Welding Hose, 1958, Compressed Gas Association anelRubber Manufacturers Association.3.5.5.2 The generally recognized colors are red for acetylene and otherfuel-gas hose, green for oxygen hose, and black for inert-gas and air hose.3.5.5.3 When parallel lengths of oxygen and acetylene host' an ' tupedtogether for convenience and to prevent tangling, not more than fonTinches ou t of twelve inches shall be covered by tape.3.5.5.4 Metal-clad or armored hose is not recommended. How{'vel', aspart of a machine or an appliance when conditions of lise m a k l ~ metalreinforq,ing a d v a n t a ~ e o u s , hose may he used in which sllch mc'tal reinforcing is exposed to neither the inside gases no r the outside atmosphere.3.5.5.5 Hose connections shall comply with tht' Standard 11 l , ~ ' l . ' (;OnfWC-tion Specifications, 1957, Compressed Gas Association.3.5.5.6 Hose connections shall he clamped or otherwis(' s('cllfl'ly fastened in a manner that will withstand, without leakage, twit-I' tIll' pressnre to which they are normally suhjected in service, bu t ill IlO ease lessthan a pressure of 300 psi. Oil-free air or an oil-free inert gas shall heused for the test.3.5.5.7 Hose showing leaks, hums, worn places, or otlwr dd(,ets rendering it unfit for service shall he repaired or r c p l a c ( ~ d .3.5.6 Pressure-Reducing Regulators3.5.6.1 Pressure-rcdudng r e ~ \ 1 l a t o r s shall he u s ( ~ d only for the ~ l \ S amIpressures for which they are intended. The regulator inlet contwctionsshall comply with Regulator Connection Slandards, 1958, (;ompn',prfonnot1 hy skilll'd I l H ( h ~ \ l l i c swho have lwen properly instnlcteu.3.5.6.4 Gages on oxygen regulators sha)] he marked "USE NO OIL."3.5.6.5 Union nuts and connections on regulators shall 1)(' inspectedbefore use to detect faulty seats which may cause 1eakage of whenthe regulators arc attached to the cylinder v111v(lS. Dmnaged Tluts or connections shall be destroyed.


30/78

3.6 ACETYLENE GENERATORS3.6.1 Approyal and Marking


3.6.1.1 Generators shall be of approved construction and shall beplainly marked with the maximum rate of acetylene in cubic feet perhour for which they are designed; the weight and size of carbide necessary for a single charge; the manufacturer's name and address; and thename or number of the type of generator.3.6.1.2 Carbide shall be of the size marked on the generator nameplate.3.6.2 Rating and Pressure Limitations3.6.2.1 The total hourly output of a generator shall not exceed the ratefor which it is approved and marked. Unless specifically approved forhigher ratings, carbide-feed generators shall be rated at one cuhic footper hour per pound of carbide required for a single complete charge.3.6.2.2 Relief valves shall be regularly operated to insure pJ'Oper functioning. Relief valves for generating chamhers shall be set to open at apressure not in excess of 15 psig. Relief valves for hydraulic hack pressurevalves shall he set to open at a pressure not in excss of 20 psig.3.6.2.3 Nonautomatic generators shall not he used for generating acetylene at pressures exceeding 1 psig, and all water overflows shall bevisible.3.6.3 Location3.6.3.1 Stationary generators should preferably hI' plac('(l ol1tside ofbuildings in generator houses constructed and locatl'd in compliance withthe applicable sections of 3.6.6, but the installation of approved p;enerators within buildings in accordance with the applicahle sections of :l.6.6of this standard is pennissible.3.6.3.2 The space around the generator shall he amp)(' for frel' , unobstructed operation and maintenance and shall pennit ready adjustmentand charging.3.6.4 Stationary Acetylene Generators(Automatic and Nonautomatic)3.6.4.1 Installation3.6 ... 1a The foundation shall be so arranged that t h ( ~ ~ e m ' r a t ( ) r will belevel and so that no excessive strain will he placed on the genf'rator or itsconnections. Acetylene generators shall he grounded.3.6.4.1 b Generators shall he placed where water will not freeze. Theuse of common salt (sodium chloride) or other corrosive chemicals forprotection against freezing is not pennitted. (For heating systems see3.6.6.3.)


31/78


3.6.4.1 c Except when generators are prepared in accordance with3.6.7.6, sources of ignition shall be prohibited in outside generator hOllsesor inside generator rooms.3.6.4.1d Water shall not be supplied through a continuous connectionto the generator except when the generator is provided with an adCCplateopen overflow or automatic water shutoff which wi1l effectively preventover:6lling of the generator. Where a noncontinuous connection is used,the supply line shall terminate at a pOint no t less than 2 in. above theregularly provided opening for filling so that the water can be ohservedas it enters the generator.3.6.4.1e Unless otherwise specifically approved, generators shall Hot hefitted with continuous drain connections leading to sewers, bllt shalldischarge through an open connection into a suitably vented outdoor~ e c e p t a c l e or residue pit which may have such connections.

NOTE: An open connection for the ~ l u c . l g e draw-off is c.lesirahh to enahle thl'generator Opt'rator to ohserve ll'ukage of gent'rating water from thl'drain vulve or S I U t l g l ~ cock.3.6.4.2 Vent Pipes3.6.4.2a Each generator shall be provided with a vent pipe of Schedule40 galvanized iron or steel, except that outside of buildings, V{'nt pip{'slarger than 4 inches in diameter may be not less than 14 gage galvanizedtubing or sheet steel.3.6.4.2b The escape or relief pipe shall he rigidly installed withouttraps and so that any condensation will drain hack to the generator .3.6.4.2c The escape or relief pipe .shnll he carried full sizt' to a sllitahltpoint outside the building. It shull terminate in n hood or lwnd locatl,dat least 12 ft. above the ground. prdl'rably above the TOof, and as faraway as practicable from windows or other openings into huildillJ,!;s andas fa r away as practicahle from sources of ignition sllch as 11tH'S O fchimneys and tracks lIsed hy locomotiws. Generating chamh('r Tt']idpipes shall not he interc.'onnected hut shall be separately led to tht out-side air. The hood or hend shall be so constructed that it will no t lw oh-structed by rain, snow, ice, insects or hirds. The outlet shall Ill' at jt'ust3 (t. from combustible construction.3.6.4.3 Gas Holders3.6.4.3a Gas holders shall beconstntcted on the gasometer principle.the bell being suitably guided. The gas bell shall move fnely withouttendency to bind and shall have a c1earanc!e of at last 2 inches from theshell.


32/78


3.6.4.3b The gas holder may be located in the generator room, in aseparate room or out-of-doors. In order to prevent collapse of the gasbell or infiltration of air due to a vacuum caused by the compressor orbooster pump or cooling of the gas, a compressor or booster cut-off shallbe proVided at a point 12 inches or more above the landing point of thebell. When the gas holder is located indoors, the room shall be ventilatedin accordance with 3.6.6.2 and heated and lighted in accordance with3.6.6.3 through 3.6.6.4.3.6.4.3c When the gas holder is not located within a heated huilding.gas holder seals shall be protected against freezing.3.6.4.3d Means shall be provided to stop the generator-feeding mechanism before the gas holder reaches the upper limit of its travel.3.6.4.3. When the gas holder is connected to only one generator, thegas capacity of the holder shall be not less than one-third of the hourlyrating of the generator.3.6.4.3f I f acetylene is used from the gas holder without increase inpressure at some points but with increase in pressure by a compressoror booster pump at other points, approved piping protective devices shallbe installed in each supply line. The low-pressure protective device shallbe located between the gas holder and the shop piping, and the mediumpressure protective device shall be located between the compressor orbooster pump and the shop piping. (see Figure 4.)

ACETYl.ENEHOLDER

l.OW - PRESSURE PIPINGPROTECTIVE DEVICE

SHOP PIPING

ACETYl .ENE COMPRESSOROR BOOSTER PUM P

MEDIUM -PRESSUREPIPING PROTECTiVe: DEVICE

Figure 4 - Protective devices for gasholders, compressors and booster pumps.


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NOTE; Approved protective equipment (designated p . ) is used to prf.>vent;( 1) backflow of oxygen into the fuel-gas supply system;(2 ) passage of u Hash hack into thl' fuel-gas SIlPP Iy systt'm; lind(3) excessive hack pressure of oxygen in the ft1t'1 gtL, supply sysltm.The three functions of the protective equipment mny ht c()mhinl'd inone device Of may be provided by ~ e p a r u t e deviet:;.3.6.4.4 Compressor or Booster Pumps3.6.4.4a The compressor or booster system shall be of an approvedtype.3.6.4.4b Wiring and electrical equipment in compressor or hoosterpump rooms or enclosures shall conform to the provisions of the NationalElectrical Code, USA Standard Cl-l965, Article 501, for Class I, Division2 locations.3.6.4.4c Compressors and booster pump eqUipment shall be located inwell-ventilated areas away from open flames, electrical or mechanicalsparks, or other ignition sources.3.6.4.4d Compressor or booster pumps s11a11 he provided with pressurerelief valves which will relieve pressure exceeding 15 psig to a safe outdoor location as provided in 3.6.4.2, or by returning the gas to the inletside or to the gas supply source.3.6.4.4e The booster pump should be water-cooled with visible watersupply or arranged with an interlocking device to shut down the hoosterpump in case of failure of the cooling-water supply.3.6.4.4f Compressor or booster pump discharge outlets shall he provided with approved protective equipment. (See Section 3.5)3.6.5 Portable Acetylene Generatars3.6.5.1 General3.6.5.1 a All portable generators shall he of a type approved for portable use.3.6.5.1 b Portable generators shall not be used within 10 feet of combustible material other than the floor.3.6 s.1c Portable generators shall no t be used in rooms of total volumeless than 35 times the total gas-generating capacity pe r charge 0 of allgenerators in the room. Cenerators shall not be used in rooms having aceiling height of less than 10 feet.

eTo obtain the gas-generating capacity ill cubic ittt pt'f charge, multiply tht' poundsof carbide per charge by 4.5.


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Safety in Welding and Cut ting I253.6.5.1d Portable generators shall be protected against free:t.ing. Theuse of salt or other corrosive chemical to prevent freezing is prohibited.3.6.5.2 Operation and Maintenance3.6.5.2a Portable generators shall be cleaned and recharged and theair mixture blown off outside buildings. In large, well-ventilated, onestory buildings, exceptions to this rule may be granted by the properauthorities.3.6.5.2b When charged with carbide, portable ~ e n e r a t o r s shall not bemoved by crane or derrick.3.6.5.2c When not in use, portable generators sh!111 not be stored inrooms in which open flames are used unless the generators contain nocarbide and have been thoroughly p u r ~ e d of acetylene. Storage roomsshall be well-ventilated.3.6.5.2d When portable acetylene generators arc to he transp()rted andoperated on vehicles, they shall be securely anchored to the vehicles. Iftransported by truck, the motor shall he tnrned off during charging,cleaning and generating periods. .3.6.5.2. Portable generators shall be located at a safe distance fromthe welding position so that they win not be exposed to sparks, slag, ormisdirection of the torch flame or overheating from hot materials orprocesses.3.6.6 Out.lde Generator Houses ond Inside Generator Rooms forStationary Acetylene Generators3.6.6.1 Con.truction3.6.6.1 a No opening In any outside generator house shall he locatedwithin five feet of any opening in another building.3.6.6.1 b Walls, Boors, and roofs of outside generator houses shall he ofnODC.'ombustible construction.3.6.6.1c When a part of the generator house is to he used fol' the storage t>r manifolding of oxygen cylinders. the space to he so ( ) c c l l p i t ~ d shaHbe separated from the generator or carhide stonlp;e section partitionwalls continuous from floor to roof or ceiling, of the tY[l(\ of constmctionstated in 3.6.6.lh. Such separation waHs shall be without openings andshall be joined to the floor, other walls and ceiling or roof in a manner toeffect a permanent gas-tight joint.3.6.6.1d Exit doors shall be located so as to be madily accessible incase of emergency.


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26/ Safety in Welding and Cutting

3.6.6.1e Explosion venting for outside generator houses and insidegenerator rooms shall be provided in exterior walls or roofs. Th e ventingarea shall be equal to not less than one square foot per 50 cubic feet ofroom volume and may consist of anyone or any combination of thefollowing: walls of light. noncombustible material preferably singlethickness, single-strength glass; lightly fastened hatch covers; lightlyfastened swinging doors in exterior walls opening outward; lightly fastened walls or roof designed to relieve at a maximum pressure of 25pounds per square foot.3.6.6.1f The installation of acetylene generators within buildings shallbe restricted to buildings not exceeding one story in height; Pfovid(d,however, that this will not be construed as prohibiting such installatiollson the roof or top Hoar of a bUilding exceeding such height.3.6.6.1g Generators installed inside buildings shall be enclosed in aseparate room of ample size.3.6.6.1h The walls, partitions, Hoors, an d ceilings of inside generatorrooms shall be of noncombustible constnlCtion having a fire-msistancerating of at least one hour. The walls or partitions shall be cOlltinuousfrom Hoor to ceiling and shall be securely anchored. At least onc wall ofthe room shall be an exterior wall.3.6.6.1 f Openings from an inside generator room to other parts of thebuilding shall be protected by a swinging type, self-closing fire door for aClass B opening and having a rating of at least one hour. Windows inpartitions shall be wired glass and approved metal frames with fixedsash. Installation shall be in accordance with the Standard fOT the In-stallation of Fire Doors and Windows, NFPA No. 80.3.6.6.2 Ventilation3.6.6.2a Inside generator rooms or outside generator homit's shall bl:'well-ventilated with vents located at Hoor and c e i l i n ~ levels.3.6.6.3 Heating3.6.6.3a Heating shall be hy steam, hot water, enclosed dl'ctricallyheated elements or other indirect means. Heating hy Hnmes or fires shallbe prohihited in outside generator houses or inside genemtor rooms, Ofin any enclosure C9mmunicatinp; with them.3.6.6.4 lighting3.6.6.4a Generator houses or rooms shall have natura11i!l:ht during daylight hours. Where artificial lighting is necessary i t shaH he restricted toelectric lamps installed in a fixed position. Unless specifically approvedfor use in a tmospheres (!ontaining acetylent!, such lamps shall he provided


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with enclosures of glass or other noncombustible material so designN)and constructed as to prevent gas vapors from r c a c h i n ~ the' lamp orsocket and to resist breakage. Rigid conduit with threaded connectionsshall be used.3.6.6.4b Lamps installed outside of wired-glass panels set in gas-tightframes in the exterior walls or roof of the generator house or room arl'acceptable.3.6.6.5 Electrical Equipment3.6.6.5a Electric switches, telephonl's and all other Il'ctrical apparatuswhich may cause a spark, unless specifically approved for use inside'acetylene generator rooms, shall he located outside the gt'nerator hot1s('or in a room or space separated from the generator room hy a gas-tightpartition, except that where the generator system is d e s i ~ m ' d so that nocarbide fill opening or other part of the ~ ( ' n ( : ' r a t o r is open to the g('lwratorhouse or room during the operation of t h ( ~ gt.'l1l'ratoT. and so that. residlll'is carried in closed piping from the residlH.' discharge' valV!' to 11 pointoutside the generator house or room. electrical l'({lIipnwnt in t h ( ~ gellerator house or room shall confonn to the provisions of the NationalElectrical Code. USA Standard Cl-1965. Article 501. for Class I, Division2 locations.3.6.7 Maintenance and Operation3.6.7.1 Unauthorized persons shall not be pem1ittt,d in o,ltside gmlt'rator houses or inside generator rooms.3.6.7.1 a Operating instnICtions shall hl' postl'll in a cOllspicllo11s plac('near the generator or kept in a suitahle plnc(' : l v : l i l a h l t ~ for f('lHly I'd('rence.3.6.7.1 b When r e c h a r g i n ~ ~ t ' n e m t o r s thl' ordl'r of olwratiolls Slwdil,din the instructions supplied by the manufadurer shall 1)(' followed.3.6.7.2a .In the case of hatch-type ~ l ' n ( ' r a t ( ) r s . wll('n tlw charge ofcarbide is exhausted and hefore additional carhide is added. tIl(' g('n


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28 ISafety in Welding and Cutting3.6.7.3 The carbide added each time the generator is recharged shallbe sufficient to refill the space provided for carbide without ramming thecharge. Steel or other ferrous tools shall not be used in distributing thecharge.3.6.7.4 Generator water chambers shall be kept fiUed to proper levelat all times except while draining during the recharging operation.3.6.7.5 Whenever repairs are to be made or the generator is to becharged or carbide is to be removed, the water chamber shall be filledto the proper level.3.6.7.6 Previous to making repairs involVing welding, soldering orother hot work or other operations which produce a source of ignition,the carbide charge and feed mechanism shall be completely removed. Allacetylene shall be expelled by completely flooding the generator shellwith water and the generator shall be disconnected from the pipingsystem. The generator shall be kept filled with water, if possible, orpositioned to hold as much water as possible.3.6.7.7 Hot repairs shall not be made in a room where there are othergenerators unless all the generators and piping have been purged ofacetylene. Hot repairs should preferably be made out-of-doors.3.7 CALCIUM CARBIDE STORAGE3.7.1 Packaging3.7.1.1 Calcium carbide shall be contained in metal packages of sufficient strength to prevent rupture. The packages shall be provided with ascrew top or equivalent. These packages shall be constructed watcrand air-tight. Solder shall not be used in such a manner that the packagewould fail if exposed to fire.3.7.1.2 Packages containing calcium carbide shall he conspicuouslymarked "Calcium Carbide - Dangerous If Not Kept Dry" or with equivalent warning.3.7.1.3 CA UTION: Metal tools, even the so-called spark resistant typemay cause ignition of an acetylene and air mixture when opening carbidecontainers.3.7.1.4 Drums should be handled so that they will not be pUllctured orruptured. FujI drums of calcium carbide should be used in rotation nsrec.'eived from the supplier.


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Safety in Welding and Cutting I293.7.1.5 A conspicuous sign should be posted on all ealcium carbidestorage rooms or buildings reading "Danger - No smoking, matches oropen lights. In case of fire do not use water," or other equivalent wording. (See Specifications for Industrial Accident Prevention Signs, USAStandard Z35.1-1959.)3.7.1.6 Sprinkler systems shall not be installed in carhide storage rooms.3.7.2 Storage Indoors3.7.2.1 storoge - Under 600 Lbs.3.7.2.1a Calcium carbide in quantities not to exceed 600 pounds maybe stored indoors in dry, waterproof and well-ventilated locations.3.7.2.1 b Calcium carbide not exceeding 600 pounds may he storedindoors in the same room with fuel-gas cylinders.3.7.2.1 c Packages of calcium carbide, except for one of each size. shallbe kept sealed. The seals shall not he broken when there is carhide inexcess of one pound in any other unsealed package of the same size ofcarbide in the room.3.7.2.2 Storage - 600 Lbs. to 5000 Lbs.: Calcium carbide exceeding600 pounds but not exceeding 5000 pounds shall be stored:3.7.2.20 In accordance with 3.7.2.3; or3.7.2.2b In an inside generator room or outside generator house; or3.7.2.2c In a separate room in a one-story building which may containother occupancies, bu t without cellar or basement heneath the carhidestorage section. Such rooms shall be constructed in accordance with3.6.6.1h and 3.6.6.li and ventilated in accordance with 3.6.6.2a. These'rooms shall be used for no other purpose.3.7.2.3 Storage - Over 5000 Lbs.3.7.2.3a Calcium carbide in excess of 5000 pounds shall he stored inone story huildings without cenar or basement and llsed for no otherpurpose, or in outside generator hOllses. The location of sl1ch storagebuildings shall he away from congested m('rcantile and manufactnringdistricts. I f the storage huilding is of noncombustihle constntction, it mayadjoin other one-story buildings if separated therefrom hy l 1 n p i c r c t ~ d firewalls; i f it is detached less than 10 feet from stich building or huildings,there shall be no opening in any of the mutually exposing sides of such


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30 I Safety in Welding and Cuttingbuildings within 10 feet. If the storage building is of combustihle construction, it shall be at least 20 feet from any other onc- or two-storybuilding. and at least 30 feet from any other huildill/!: ('xcl'l!ding twostories.3.7.3 Storage Outdoors3.7.3.1 Calcium carbide in unopened metal containers mny he storedoutdoors.3.7.3.2 Carbide containers to be stoTed outdoors . ~ h n l l 1)(' examilled tomake sure that they are in good condition. Periodic r('-exnrninatiolls shallbe made for nIsting or other damage to a container that might aff('et itswater or air tightness.3.7.3.3 Containers should be stored horizontallv in singll' or clol1hkrows. Ample space should be provided between rO'ws or puil:s of rows tofacilitate periodic re-examination and th( r('moval of eontaiw'rs fOl1nddefective. The bottom tier of each row shall Ill' ph\t'(d Oil wood('l! planking or equivalent. so that the cont,ainers will not come ill c . . ~ > 1 l t a c t with thl'ground or ground water.3.7.3.4 Storage areas shall be at least 10 ft'ct frolll lim's of adjoiningproperty that may be built npon.3.7.3.5 Containers of carbide which have heen ill storagl' the' IOllw'stshall be used first.3.8 PUBLIC EXHIBITIONS AND DEMONSTRATIONS3.8.1 General3.8.1.1. These rC(luircments an ' intended to promotl! tIll' safl' IIsagl' ofoxygen-fuel-gas systems in welding and cutting operations at plIlllie exhibitions, demonstrations, displays: and tradt shows )'(+('I"1'l'(\ to hpl'l'illafter as the "site:'3.8.1.2 Installation and opl'ratioll of w d d i n ~ , clltting and n'laft,dtqllipment shall he dOnl' by, or IIndl'r tIll' supervisio1l of, a t'lIlllpt'll'ntoperator to insure the p(rsonal prot('('tioll of viewers HIl l I d('lllollstratorsas well as the protection from fin'. of matt'rials in aIHI arolilHI tit! sill' nndthe building itself.3.8.1.3 Prucedures3.8.1.3a Cylindt'fs containing comprpss('d gaSl'S for l l . ~ l ' at tht Sitl' shallnot he charged in ('xc('ss of one-half thl'ir maximlllll IWl'l11issihll' C()Jltt 'llt.(Cylinders of nonli'llJ(,n(d gas('s ancI acctyI('I1l' shnl1 1)(' ('''nrw'(I to notmore than one-half their maximllm lwnnissihlP e 1 l l 1 r / ! : l ~ l l pn'sslln' il l psi/!:.Cylinders of liqlwn(d gast's shall 1)(' charge!1 to lIot lIIor(' thall IIlIl-haHthl' maximum p(mnissihlt, capacity ill pOllnds.)


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..


3.8.1.3b Cylinders located at the site shall be connected for useexcept that enough additional cylinders may be stored at the site tofurnish' approximately one day's consumption of each gas used. Othercylinders shall be stored in an approved storage urea, preferahly outdoors, but this storage area shall not be located near a bUilding exit.3.8.1.3c Cylinders in excess of 40 pounds total weight heing transported to or from the site shall be carried on a hand or motorized truck.3.8.1.3d The site shan be constructed, equipped and operated in sucha manner that the demonstration will be carried out so as to minimize thepossibility of injury to viewers.3.8.1.3. Sites involving the use of compressed gases shall be locatedso as not to interfere with the egress of people during an emergency.3.8.1.3f The Fire Department shall be notified in advance of such UStof the site.3.8.1.39

(1) Each site shall be provided with a portable fire e x t i n g t 1 i s h ( ~ r ofappropriate size and type and with a pail of water.(2) The public and combustible matt'rials at the liite shull he pro-tected from flames, sparks, and molten metal.

3.8.1.3h Hoses shall be located and protected so that they will not hephysically damaged.3.8.1.31

(1) Cylinder valves shall be closed when t'quipmC'nt is unattended.(2) Where caps are provided for valve protection. snch caps shall hein place except when the cylinders are in service or conncch,dready for service.(3) Cylinders shall be loclltecl or secured so that they ('anllot heknocked over.

4. Application, Installation and Operationof Arc Welding and Cuffing Equipment

4.1 GENERAL4.1.1 Welding equipment shall be chosen for safe application to thework to be done as specified in 4.2.4.1.2 Welding equipment shall be installed safely as specified hy 4.3.


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32 ISafety in Welding and Cutting

4.1.3 Worlanen designated to operate arc welding equipment shallhave been porperly instnlcted and qualified to operate such equipment asspecified in 4.4.4.2 APPLICATION OF ARC WELDING EQUIPMENT4.2.1 Genera'4.2.1.1 The safety aspects of welding should be given considerationwhen choosing arc welding equipment for the job to be done. Assuranceof consideration of safety in design is obtainahle hy c h o ( ) s i n ~ apparatuscomplying with the Requirements for Electric Arc-Weldin.g Al)]JlIrlItlls,USA Standard CB7.1-196.'3, National Electrical Manufa cturers Associationor the Safety Standard fOT Transformer-TYlJe Arc-Welding M l l C l l i l l l ' . ~ ,USA Standard C33.21956, Underwriters' Lahoratories. Spt'cial purposemachines not covered by these standards should confonn in all applicahlerespects to these standards. .4.2.2 Environmental Conditions4.2.2.1 Standard machines for arc w e l d i n ~ s('rvic(' shall he d('sigJl('dand constructed to carry their rated load with ratN1 h'mpl'rat1lJ'e riseswhere the temperature of the c o o l i n ~ air docs llot ('xct'pd ..lODe (104F)an d where the altitude does not cxceed 3300 feet, and shall he suitablefor operation in atmospheres containing gas('s, dust and l i ~ h t rays produced by the welding arc.4.2.2.2 Unusual service conditions mav exist, an d in such cirCI1111stallC(,Smachines shall be especially designed safely n l ( ' ( ~ t the T('qnin'mt'nts ofthe service. Chief among these conditions an':

1. Exposure to unusually corrosive fumes.2. Exposure to steam or excessiwhllmidity.'3. Exposure to excessive oil vapo)".4. Exposure to f1ammahl( p;asts.5. Exposure to almonlU11 vihration or shock.6. ExpoSUT!' to excl'ssive dust.7. Exposure to wcather.R. Exposure to unusual seacoast or shipboard comlitions.

4.2.3 Voltage4.2.3.1 Open circlIit (No load) v ( ) l t a ~ ( ' s of arc w('\


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Safety in Welding and Cuttin{!, I33(b) Direct-current Machines1. Manual arc welding and cutting - 100 volts.2. Automatic (machine or mechanized) arc welding and cutting-100 volts.(c) When special welding and cutting processes require values ofopen circuit voltages higher than the above, means shall be providea toprevent the operator from making accidental contact with the high voltage by adequate insulation or other means.(d) For AC welding under wet conditions or wann surroundingswhere perspiration is a factor, the use of reliable automatic controls for

reducing no load voltage is recommended to reduce the shock hazard.4.2.4 Design4.2.4.1 A controller integrally mounted in an elt'ctric motor drivenwelder shall have capacity for carrying rattd motor current. shall becapable of making and interrupting stalltd rotor current of the motor,and may serVe as the running overcurrent device if provided with thenumber of overcurrent units as specified hy the NatiorUil Ele(.'triclll Code,USA Standard Cl-1965, Table 430-146. 04.2.4.2 On all types of arc welding machines, control apparatl1s shall hl'enclosed except for the operating wheels, levers or handks. Controlhandles and wheels should be large e n o u ~ h to 1)(' easily graspt'cl hy agloved hand.4.2.4.3 Input power tenninals, tap chang


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34 ISafety in Welding and Cutting4.2.4.5 No connections for portable control devices such as pushbuttons to be carried by the operator shall be connected to an AC circuitof higher than 120 volts. Exposed metal parts of portable control devicesoperating on circuits above 50 volts shall be grounded by a groundingconductor in the contro] cable.4.2.4.6 Auto transfonners or AC reactors shall not be used to drawwelding current directly from any AC power source haVing a voltageexceeding 80 volts.4.2.5 Equipment Loading4.2.5.1 Care should be taken in applying arc welding equipment toinsure that the current rating chosen is adequate to handle the joh. Wdding machines should not be operated above their ClIrrent ratings andcorresponding rated duty cycles listed in the standards or ahove thelimits specified by the manufacturer. Consideration should he given tothe fact that actual welding currents may be higher thun shown by imlicators on the machines i f welding is done with short leads or low arcvoltages; particularly high over-currents are likely on general-purposewelding machines when using low arc voltage prOCCSSl'S sitch us aircarbon-arc cutting, oxygen-arc cutting or gas tungstt'n-arc w t ' l d i n ~ .4.2.5.2 Welding cables should be of the extra flexihl(, typt' dl'si!-,(nt,despecially for the rigors of welding service and of size LHbltlate forcurrent and duty cycles reasonahly to be expected. Special ath'ntiollshould be paid to insulation of cables 11sed with C'C}uipnwnt which includes high voltage high frequency oscillators. For a V ( ' r a ~ ( ' manualshielded metal-arc w d d i n ~ duty cycles. the f o n o w i n ~ tahle ma y he \ls('(.\as a guide for curn'nt capadty; for automatk or semi-automatic: illstullations where duty cydcs approach l O O ~ : ~ " cahles should he in accordancewith Chapter 3, Tahles 310-13 und 310-15. of the Nl/ti01Ull l ~ l e c t r i c a lCode. USA Standard CI-HJ65. These r n t i n ~ s an' for op('ratiol) withcables exposed to air sil1g1y and not hundled. Clldos(,(l ill { . ~ ) I l d l l i t orcoiled.Table l-Cahlt.' Sizes for Arc Welding Machilles Bas(,


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Safety in Welding and Cutting 13S

4.3 INSTALLATION OF ARC WELDING EQUIPMENT4.3.1 General4.3.1.1 Installation including power supply shall be in accordance withthe requirements of the National Electrical Code, USA Standard (;1-196,5.4.3.2 Grounding4.3.2.1 The frame or case of the welding machine (except enginc driV


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36 ISafety in Welding and Cutting4.3.2.6 When during construction or modification, a building or anyother fabricated metal stnlCture is used for a welding current returncircuit, it should be checked to ascertain whether proper electrical contact exists at all joints. Sparking or heating at any point shall cause rejection of the structure as a return circuit.4.3.2.7 Where a structure, conveyor, or fixture is regularly employed asa welding current return circuit, joints shall be bonded or provided withadequate current collecting devices and appropriate periodic inspectionshould be conducted to ascertain that no condition of electrolysis orshock, or fire hazard exists by virtue of such use.4.3.2.8 All ground connections shall be checked to detennine that theyare mechanically strong and electrically adequate for the required current.4.3.2.9 When it becomes necessary to carry cables some distance fromthe machines, they should be substantially supported overhead, if practicable. I f this cannot be done, and cables are laid on the floor or ground,they should be protected in such a manner that they will not be damaged,entangled or interfere with safe passage. Special care should he taktm tosee that welding supply cables arc not in proximity to power snpplycables or other high voltage conductors.4.3.3. Supply Connections and Condudors4.3.3.1 A disconnecting switch or controller shall bf' provided at 0) 'near each welding machine which is not equipped with snch a switch orcontroller mounted as an integral part of the machine. The switch shallbe in accordance with the National Electrical Code, USA StandardCl-1965. Over current protection shall he provid('(] as speclfi('(l in theNational Electrical Code, USA Standard Cl-1965, A r t i d ( ~ 630. A d i s c o n ~nect switch with overload protection or equivalent disconnl'ct and protection means, pennitted by the National Electrical Code, shall h(, providedfor each outlet intended for connection to a portahle welding machine.4.3.3.2 For individual welding machines, the ratcd cl1rrt'llt-enrryingcapacity of the supply conductors shan be not less than t]le rattd primarycurrent of the welding machines.4.3.3.3 For groups of welding machines, the rated current-carryingcapacity of conductors may he less than the sum of the rnh'd primarycurrents of the welding mnchines supplied. The conductor r a t i n ~ shallbe detenninccl in each case according to the machine l o a ( l i l l ~ hascd onthe use to he made of each welding machine nnd the n l 1 o w a l l l . ' t . ~ pC'mlis-sible in the event that all the weldirlg machines supplied by the COll-


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Safety in Welding Cutting 137

ductors will not be in use at the same time. The load value used for eachwelding machine shall take into account both the magnitude and theduration of the load while the machine is in use. Conductor ratings, basedon 100% of the rated primary current of the two largest welding machines, 85% for the third largest welding machine, 70% for the fourthlargest welding machine, and 60% of the rated primary current for all theremaining welding machines, should provide an ample margin of safetyunder high production conditions with respect to the maximum permissible temperature of the conductors. Percentage values lower than thosegiven are permissible in cases where the work is such that a high operatingduty cycle for individual machines is impossible; conversely, for groupsof simultaneously operating automatic welding machines higher percentage values may be required.4.3.3.4 In operations involving several welders on one structure, DCwelding process requirements may require the use of both polarities; orsupply circuit limitations for AC welding may require distribution ofmachines among the phases of the supply circuit. In such cases no loadvoltages between electrode holders will be 2 times normal in DC or 1,1.41, 1.73 or 2 times normal on AC machines. Similar voltage differenceswill exist if both AC and DC welding are done on the same structure.Care should, therefore, be taken to eliminate the probability of welderstouching two electrode holders simultaneously. I f this cannot he donemachines shall be connected as follows: .

(1) All DC machines shall be connected with the same polarity."(2) All AC machines shall be connected to the same phase of thesupply circuit and with the same instantaneous polarity."4.4 OPERATION AND MAINTENANCE4.4.1 Workmen assigned to operate or maintain arc w c l d i n ~ equipmentshall be acquainted with the requirements of Section 4. especially thefollowing parts of Section 4; also the requirements of Section 6, Fin'Prevention and Protection; Section 7, Protection of Personnel and Sf.'ction8, Health Protection and Ventilation; if doing gas-shielded arc welding,also Recommentlecl Safe Practices for Gas-Shielded Arc Welcling, A6.1-66,American Welding Society.4.4.2 Before starting operations all connections to the machine shall ht:checked to make certain they are properly made. The work lead shall hefirmly attached to the wor\


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Safety in Welding and Cutting I394.4.9.2 The welder should never pennit the live metal parts of anelectrode holder to touch his bare skin or any wet covering of his body.He should also protect himself from electrical contact with the work orground by dry insulating material; particularly, he should be protectedagainst large area contacts by insulation when working in a sitting orprone position. Adequately dry gloves are also recommended. He shouldnot use electrode holders for manual shielded metal-arc welding withoutwell insulated; jaws in good repair. Electrode holders must not be cooledby immersion in water. Water-cooled holders for gas tungsten-arc andgas metal-arc welding must not be used if any water leak exists. Thewelding machine supplying power to the arc must always be turned offwhenever changing electrodes in gas tungsten-arc electrode holders, orwhenever threading coiled electrodes into gas metal-arc equipment. Special precautions should be taken to prevent shock-induced falls when thewelder is working above ground level. The welder should not coil orloop welding electrode cable around parts of his body. Cables withsplices within 10 ft. of the holder shall not be used.4.4.10 Maintenance4.4.10. , All arc welding equipment should be maintained in safe working order at all times. Periodic inspections are strongly recommended . .The operator should report any equipment defect or safety hazard to hissupervisor and the use of the equipment shall be discontinued until itssafety has been assured. Repairs shall be made only hy qualified personnel.4.4.10.2 Welding equipment should be maintained in good mt'chanicaland electrical condition to avoid unnecessary huzards. Commutatorsshould be kept clean to prevent excessive Hashing. Flllmmahl(' li1lllitisshould not he used for cleaning commututors; fine sand paper such asNo. ()() or commutator polish should he used. Rectifiers should he frequently inspected to detect accumulutions of dust or lint that wouldinterfere with ventilation. Electrical coil ventilating ducts should hesimilarly inspected and cleaned. It is a good practice to hIow Ollt theentire welding machine with clean dry compressed nir. Fuel syst('ms onengine driven machines should be inspected and checked for p ( ) s s i h l ( ~leaks and accumulations of water that might cause rusting. Rotatinf,!; andmoving components should be kept properly lubricated .4.4.10.3 Welding equipment used in the oplm should 1)(' prohch.dfrom inclement weather conditions. Protective cover shan not ohstnlCt theventilation necessary to prevent overheating of the machine.

Documents

ANSI Z49-1 (1967) Safety in Welding and Cutting