Welding, Cutting, and Brazing Techniques

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1. Welding, Cutting, and Brazing MODULE 16 2. Hazards of Welding Operations  Fire hazards  Metal splatter  Electric shock 2 ©2006 TEEX  Electric shock …
  • 1. Welding, Cutting, and Brazing MODULE 16
  • 2. Hazards of Welding Operations  Fire hazards  Metal splatter  Electric shock 2 ©2006 TEEX  Electric shock  Explosion hazards  Released gases  Radiant energy  Where would these hazards be found on oil and gas well sites?
  • 3. Three Basic Types of Welding  Gas – Slower and easier to control than electric arc. Uses gas flame over metals until molten puddle is formed. Most popular fuels used with oxygen include acetylene, mapp gas, and hydrogen. 3 ©2006 TEEX gas, and hydrogen.  Arc – Two metals are joined by generating an electric arc between a covered metal electrode and the base metal.  Oxygen and Arc Cutting – Metal cutting in welding is the severing or removal of metal by a flame or arc.
  • 4. Oxygen and arc cutting  Most common cutting processes :  Oxygen Cutting: Metal is heated by gas flame and an oxygen jet does the cutting. 4 ©2006 TEEX  Arc Cutting: Intense heat of electric arc melts away the metal.
  • 5. Regulations  29 CFR 1910 Subpart Q  General Industry  29 CFR 1926 Subpart J 5 ©2006 TEEX  29 CFR 1926 Subpart J  Construction  API RP 54 Section 20  Hotwork, Welding, and Flame Cutting Operations
  • 6. General Requirements 29 CFR 1910.252
  • 7. Fire Prevention Safeguards  Fire Hazards should be removed if the welded object cannot be readily moved.  Guards should be used if removing fire 7 ©2006 TEEX  Guards should be used if removing fire hazards is not possible.  Restrictions apply (no cutting or welding allowed) if none of the above is possible.
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  • 9. Special Precautions  Protect nearby combustible materials from sparks that might escape through openings in floors or walls.  Fire Extinguishers must be ready for instant 9 ©2006 TEEX  Fire Extinguishers must be ready for instant use.  Fire Watch lasting at least 30 min after welding or cutting operations is required if more than a minor fire might develop and if certain combustible materials are present.
  • 10. Special Precautions  Authorization: A responsible individual must inspect the area and designate precautions, preferably by written 10 ©2006 TEEX permit.  Floors: Combustible materials must be swept 35 feet away; combustible floors must be wetted or protected (while preventing arc welding shock)
  • 11. Special Precautions  Prohibited areas for welding:  Unauthorized by management  Where sprinklers are impaired  Explosive atmospheres 11 ©2006 TEEX  Explosive atmospheres  Near storage of large quantities of readily ignitable materials  Relocation of Combustibles: Combustibles shall be moved 35 feet away or properly protected or shielded.
  • 12. Special Precautions  Ducts: Ducts & conveyor systems that might carry sparks must be shut down.  Combustible walls must be shielded or guarded. 12 ©2006 TEEX guarded.  Noncombustible walls, partitions or ceilings (when welded) require opposite-side moving of combustibles or a fire watch.  Combustible cover: No welding on certain metal building components having combustible covers or layers.
  • 13. Special Precautions  Pipes (or any metal) close enough to combustibles to cause ignition by conduction may not be cut or welded. 13 ©2006 TEEX  Management responsibilities:  Establish proper areas and procedures  Designate responsible individual  Ensure training  Advise contractors of hazards
  • 14. Special Precautions  Supervisor responsibilities:  Safety of equipment & procedures  Determine combustibles & hazardous areas  Protect combustibles from ignition through 14 ©2006 TEEX  Protect combustibles from ignition through moving, shielding and scheduling  Secure authorizations  Give go-ahead to cutter or welder  Ensure fire protection  Ensure fire watches if required
  • 15. Welding or Cutting Containers  Used containers must be cleaned of flammable materials or other materials that could release toxic of flammable 15 ©2006 TEEX vapors when heated.  Venting & purging is required for hollow spaces or cavities.
  • 16. Confined Spaces  Precautions must be taken during long* pauses in arc welding to prevent  accidental contact of electrodes 16 ©2006 TEEX  accidental contact of electrodes  torch valve gas leaks in gas welding. *During lunch or overnight
  • 17. Protection of Personnel  Railing or other suitable fall protection must be provided as required.  Welding cable and other equipment must be kept clear of passageways, 17 ©2006 TEEX must be kept clear of passageways, ladders and stairways.  Eye protection and protective equipment of specific appropriate types must be worn. Nearby workers must be protected from arc welding rays.
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  • 19. Protection of Personnel  Work in confined spaces requires consideration of:  Ventilation  Securing cylinders and machinery 19 ©2006 TEEX  Securing cylinders and machinery  Lifelines  Electrode removal (arc welding)  Gas cylinder shutoff (gas welding & cutting)  Warning signs for hot metal
  • 20. Health Protection & Ventilation  General requirements for protecting welders are based on 3 factors:  Dimensions of space (especially ceiling 20 ©2006 TEEX  Dimensions of space (especially ceiling height) in which welding is to be done  Number of welders  Possible evolution of hazardous fumes, gases, or dust according to the metals involved.
  • 21. Natural and Mechanical Ventilation  Must not be restricted by screens  Sufficient to keep concentrations <PEL  Mechanical ventilation required for: 21 ©2006 TEEX  Mechanical ventilation required for:  Metals not described here  Spaces <10,000 feet per welder  Rooms with ceilings lower than 16 feet  Confined spaces or areas with barriers to natural cross ventilation
  • 22. Dilution Ventilation  Contaminant should travel away from breathing zone. 22 ©2006 TEEX breathing zone.  Local exhaust ventilation may be more effective. Poor Fair Good Best
  • 23. Ventilation  Confined space: ventilation first; respirators if ventilation impossible  Specific rules for specific chemicals 23 ©2006 TEEX  Specific rules for specific chemicals  Outdoors: Just stay below PEL
  • 24. Transmission pipeline  Special rules in 1910.252(d)(1)  Special electric shock protection for wet conditions  Pressure testing: Worker and public 24 ©2006 TEEX  Pressure testing: Worker and public protection against blowing out or loose dirt  Construction: API Std. 1104-1968  Flammable substance lines: API Std. PSD No. 2201-1963  X-ray inspection: ANSI Z54.1-1963
  • 25. Oxygen-Fuel Gas Welding & Cutting  General Requirements  Flammable mixtures of fuel gases and air or oxygen must be guarded against. 25 ©2006 TEEX  Maximum pressures of 15 psi for acetylene must be observed (with certain rare exceptions).  Approved apparatus.  Competent personnel in charge of supply equipment
  • 26. Cylinders & Containers  Approval & Marking:  DOT compliant  Legibly marked  ANSI compliant connections 26 ©2006 TEEX  ANSI compliant connections  Valve protection
  • 27. Cylinders & Containers: Storage  Away from heat sources (such as radiators)  When inside buildings:  Well-protected, ventilated, dry location at least 20 ft from combustibles 27 ©2006 TEEX ft from combustibles  Assigned storage spaces, protected from damage & tampering  When empty: closed valves  When not in use: hand-tight valve protection caps
  • 28. Oxygen Storage  Protect oxygen cylinders from fire hazards such as acetylene: 28 ©2006 TEEX  Distance: 20 ft from fuel-gas cylinders or combustibles, or  Barrier: 5 ft high noncombustible partition with half-hour fire- resistance rating
  • 29. Arc Welding & Cutting  Use compliant equipment  Special design for exposure to weather, flammable gases, marine conditions… 29 ©2006 TEEX flammable gases, marine conditions…  Workmen who operate or maintain arc welding equipment shall be acquainted with the requirements of 1910.254 and 1910.252
  • 30. Arc Welding & Cutting  Electrode holders when not in use must be kept from shocking people and objects.  Protect against electric shock:  Never use cables with splices within 10 feet (3 m) 30 ©2006 TEEX  Never use cables with splices within 10 feet (3 m) of the holder  The welder should not coil or loop welding electrode cable around parts of his body  Maintenance must ensure safety:  Damaged cables & equipment must be replaced.  Work and cables must be joined properly and have adequate insulation.
  • 31. Operating procedures  Cylinders, cylinder valves, couplings, regulators, hose, and apparatus kept free from oily or greasy substances 31 ©2006 TEEX  Oxygen cylinders shall not be handled with oily hands or gloves  A jet of oxygen must never be permitted to strike an oily surface, greasy clothes, or enter a fuel oil or other storage tank
  • 32. Operating procedures When transporting cylinders by a crane:  Use a cradle or suitable platform  Never use slings or electric magnets 32 ©2006 TEEX  Never use slings or electric magnets  Valve-protection caps always in place
  • 33. Operating procedures  Never use valve-protection caps to lift cylinders from one vertical position to another 33 ©2006 TEEX another  Never use bars under valves or valve-protection caps to pry cylinders loose  may use warm (not boiling) water
  • 34. Operating procedures Before cylinders are moved:  Regulators shall be removed  Valve-protection caps, when 34 ©2006 TEEX  Valve-protection caps, when provided for, shall be put in place  Unless cylinders are secured on a special truck
  • 35. Operating procedures  Cylinders without fixed hand wheels shall have keys, handles, or nonadjustable wrenches on valve 35 ©2006 TEEX stems while cylinders are in service
  • 36. Operating procedures  Fuel-gas cylinders shall be placed with valve end up whenever they are in use  Liquefied gases shall be stored and 36 ©2006 TEEX  Liquefied gases shall be stored and shipped with the valve end up
  • 37. Operating procedures  Before connecting a regulator to a cylinder valve:  Open the valve slightly; close immediately  Open the valve while standing to one 37 ©2006 TEEX  Open the valve while standing to one side of the outlet; never in front of it  Never crack a fuel-gas cylinder valve near other welding work or near sparks, flame, or other possible sources of ignition
  • 38. Operating procedures  Always open the cylinder valve slowly  Never open an acetylene cylinder valve more than 1.5 turns of the spindle, and 38 ©2006 TEEX more than 1.5 turns of the spindle, and preferably no more than 3/4 of a turn
  • 39. Hose and hose connections  Replace hose with leaks, burns, worn places, defects  When parallel lengths of oxygen and 39 ©2006 TEEX  When parallel lengths of oxygen and fuel hose are taped together, not more than 4 of 12 inches covered by tape
  • 40. Test Your Knowledge  How long must a fire watch continue?  A radius of 35 feet. How far away must combustible materials be kept from welding?  At least 30 minutes. 40 ©2006 TEEX be kept from welding?  Who is responsible for making fire watchers available?  During work in confined spaces, what must be left outside?  Gas cylinders & welding machines.  Supervisor.
  • 41. Examples & Diagnosis 41 ©2006 TEEX
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