Hot Tapping - Potential Hazardous Consequences

Potential Hazardous Consequences

Personal Injury (Safety / Human Health) 

• Hot work presents direct personnel hazards to those involved in the task, or to those 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 particularly sensitive to burning, including 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 not 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. 

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 resulting in the release of hydrocarbons, 

• Arc from welding, possibly setting off fire detection / mitigation systems (i.e., deluge systems, alarms resulting in possible unit shutdowns, 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 hot tap 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 prior to start of the job, backflow can happen if one cylinder goes empty during operation which can cause:  

      • A system pressure imbalance. 

      • Mixing of oxygen 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) 

Chemical Release / Environmental Impact (On-Site and Off-Site) 

In addition to the Personal Injury and Property Damage 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. 

• Injuries to on-site personnel not directly involved in the hot tap operation, or to emergency responders or members of the public (off-site) 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.