Welding

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1. Slide 1

   Welding, Cutting, and Brazing

   • MODULE 16
2. Slide 2

   Hazards of Welding Operations

   • Fire hazards
   • Metal splatter
   • Electric shock
   • Explosion hazards
   • Released gases
   • Radiant energy
   • Where would these hazards be found on oil and gas well sites?
3. Slide 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.
   • 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. Slide 4

   Oxygen and arc cutting

   • Most common cutting processes :
   • Oxygen Cutting: Metal is heated by gas flame and an oxygen jet does the cutting.
   • Arc Cutting: Intense heat of electric arc melts away the metal.
5. Slide 5

   Regulations

   • 29 CFR 1910 Subpart Q
   • General Industry
   • 29 CFR 1926 Subpart J
   • Construction
   • API RP 54 Section 20
   • Hotwork, Welding, and Flame Cutting Operations
6. Slide 6

   29 CFR 1910.252

   • General Requirements
7. Slide 7

   Fire Prevention Safeguards

   • Fire Hazards should be removed if the welded object cannot be readily moved.
   • 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.
8. Slide 8

   FOR EXAMPLE…

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9. Slide 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 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. Slide 10

    Special Precautions

    • Authorization: A responsible individual must inspect the area and designate precautions, preferably by written permit.
    • Floors: Combustible materials must be swept 35 feet away; combustible floors must be wetted or protected (while preventing arc welding shock)
11. Slide 11

    Special Precautions

    • Prohibited areas for welding:
    • Unauthorized by management
    • Where sprinklers are impaired
    • 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. Slide 12

    Special Precautions

    • Ducts: Ducts & conveyor systems that might carry sparks must be shut down.
    • Combustible walls must be shielded or 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. Slide 13

    Special Precautions

    • Pipes (or any metal) close enough to combustibles to cause ignition by conduction may not be cut or welded.
    • Management responsibilities:
    • Establish proper areas and procedures
    • Designate responsible individual
    • Ensure training
    • Advise contractors of hazards
14. Slide 14

    Special Precautions

    • Supervisor responsibilities:
    • Safety of equipment & procedures
    • Determine combustibles & hazardous areas
    • 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. Slide 15

    Welding or Cutting Containers

    • Used containers must be cleaned of flammable materials or other materials that could release toxic of flammable vapors when heated.
    • Venting & purging is required for hollow spaces or cavities.
16. Slide 16

    Confined Spaces

    • Precautions must be taken during long* pauses in arc welding to prevent
    • accidental contact of electrodes
    • torch valve gas leaks in gas welding.
    • *During lunch or overnight
17. Slide 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, ladders and stairways.
    • Eye protection and protective equipment of specific appropriate types must be worn. Nearby workers must be protected from arc welding rays.
18. Slide 18

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19. Slide 19

    Protection of Personnel

    • Work in confined spaces requires consideration of:
    • Ventilation
    • Securing cylinders and machinery
    • Lifelines
    • Electrode removal (arc welding)
    • Gas cylinder shutoff (gas welding & cutting)
    • Warning signs for hot metal
20. Slide 20

    Health Protection & Ventilation

    • General requirements for protecting welders are based on 3 factors:
    • 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. Slide 21

    Natural and Mechanical Ventilation

    • Must not be restricted by screens
    • Sufficient to keep concentrations <PEL
    • 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. Slide 22

    Dilution Ventilation

    • Poor
    • Fair
    • Good
    • Best
    • Contaminant should travel away from breathing zone.
    • Local exhaust ventilation may be more effective.
23. Slide 23

    Ventilation

    • Confined space: ventilation first; respirators if ventilation impossible
    • Specific rules for specific chemicals
    • Outdoors: Just stay below PEL
24. Slide 24

    Transmission pipeline

    • Special rules in 1910.252(d)(1)
    • Special electric shock protection for wet conditions
    • 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. Slide 25

    Oxygen-Fuel Gas Welding & Cutting

    • General Requirements
    • Flammable mixtures of fuel gases and air or oxygen must be guarded against.
    • Maximum pressures of 15 psi for acetylene must be observed (with certain rare exceptions).
    • Approved apparatus.
    • Competent personnel in charge of supply equipment
26. Slide 26

    Cylinders & Containers

    • Approval & Marking:
    • DOT compliant
    • Legibly marked
    • ANSI compliant connections
    • Valve protection
27. Slide 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
    • Assigned storage spaces, protected from damage & tampering
    • When empty: closed valves
    • When not in use: hand-tight valve protection caps
28. Slide 28

    Oxygen Storage

    • Protect oxygen cylinders from fire hazards such as acetylene:
    • Distance: ≥20 ft from fuel-gas cylinders or combustibles, or
    • Barrier: ≥5 ft high noncombustible partition with half-hour
    • fire-resistance rating
29. Slide 29

    Arc Welding & Cutting

    • Use compliant equipment
    • Special design for exposure to weather, 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. Slide 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) 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. Slide 31

    Operating procedures

    • Cylinders, cylinder valves, couplings, regulators, hose, and apparatus kept free from oily or greasy substances
    • 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. Slide 32

    Operating procedures

    • Before connecting a regulator to a cylinder valve:
    • Open the valve slightly; close immediately
    • 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
33. Slide 33

    Operating procedures

    • Always open the cylinder valve slowly
    • Never open an acetylene cylinder valve more than 1.5 turns of the spindle, and preferably no more than 3/4 of a turn
34. Slide 34

    Hose and hose connections

    • Replace hose with leaks, burns, worn places, defects
    • When parallel lengths of oxygen and fuel hose are taped together, not more than 4 of 12 inches covered by tape
35. Slide 35

    Test Your Knowledge

    • How long must a fire watch continue?
    • At least 30 minutes.
    • How far away must combustible materials be kept from welding?
    • A radius of 35 feet.
    • Who is responsible for making fire watchers available?
    • During work in confined spaces, what must be left outside?
    • Supervisor.
    • Gas cylinders & welding machines.
36. Slide 36

    Examples & Diagnosis

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