Hot Work - Potential Hazardous Consequences

Property Damage (Fire / Explosion)

• Creating an ignition source (flame, heat, sparks, non-intrinsically safe equipment, molten metal or direct flames) in a combustible atmosphere (flammable materials/vapors) leading to fire or explosion.
  • Caution must be taken when working near openings or cracks in walls, flooring, open doorways and windows.
• Impinging heat to surrounding process equipment, causing possible thermal expansion re-sulting in the release of hydrocarbons,
• Arc from welding, possibly setting off fire detection / mitigation systems (i.e., deluge sys-tems, alarms resulting in possible unit shut downs, etc.)
• Interference with other simultaneous work in close proximity (e.g., work involving breaking containment and potential release of combustible gases while hot work is present.)
• Hazards associated with welding equipment:
  • Damage and defective parts, if not replaced prior to start of the job
  • Improper grounding
  • Oxy-fuel equipment
    • If oxy-acetylene cylinders do not have sufficient material in the cylinders pri-or to start of the job, backflow can happen if one cylinder goes empty during operation which can cause:
      • A system pressure imbalance.
      • Mixing of oxy and fuel inside the hose.

• Flashback caused by reverse flow of gas through the torch and back through to the hose, regulator and/or cylinder, potentially causing an explosion
• Fire or explosion caused by ignition of flammable/combustible vapors/materials present in processing equipment such as tanks, vessels and piping, etc., that have void spaces or liners (i.e., double-walled tanks and piping, double-bottom tanks)

Personal Injury (Safety / Human Health)

Hot work presents direct personnel hazards to those involved in the task, or working nearby.

• Skin/eye burns and electric shock are potential direct hazards.  A hot surface or a spark can burn skin, either by contact or from radiated heat. The eyes are particular-ly sensitive to burning, including that from light radiation - “arc eye”.
• Potential of personnel overexposure to welding or flame cutting fumes, especially:
  • If ventilation is inadequate.
  • Inappropriate or insufficient PPE.

• Injuries from sparks, etc., to personnel working in the area or passing nearby (or at a lower level below the work) may occur if the area is not properly isolated or access is restricted and there is no additional protection such as a fire blanket.
  • While the direct hazards of hot work are important, the risks from fires and explosions are typically more significant, especially in operational areas.

Chemical Release / Environmental Impact (On-Site)

In addition to the Property Damage and Personal Injury consequences stated above, facilities must also consider the potential for escalation that could result in environmental damage or additional personal injuries occurring on-site.

• Environmental damage due to releases to the air, soil, or bodies of water resulting from hot work related fires, explosions, equipment damage, etc.
• Personnel injuries due the release of flammable, combustible vapors, or toxic materials due to products of combustion resulting from hot work related fires.
• Personal injuries due to fire escalation or explosions resulting from hot work related fires.

Chemical Release / Environmental Impact (Off-Site)

In addition to the Property Damage and Personal Injury consequences stated above, facilities must also consider the potential for escalation that could result in environmental damage or additional personal injuries occurring on-site.

• Environmental damage due to releases to the air, soil, or bodies of water resulting from hot work related fires, explosions, equipment damage, etc.
• Personnel injuries due the release of flammable, combustible vapors, or toxic materials due to products of combustion resulting from hot work related fires.
• Personal injuries due to fire escalation or explosions resulting from hot work related fires.