Hot Work in Confined Spaces

There are a multitude of facilities that require welding, cutting, and other hot work. Some environments lack room and become confined spaces.
Confined spaces have the following characteristics:

  • Limited space, entry, or exit
  • Poor ventilation – lack of safe breathing air and possible buildup of hazardous gases, fumes, and particles.

    Examples of Confined Spaces

  • Small rooms
  • Pits
  • Vats
  • Storage tanks
  • Sewers
  • Degreasers
  • Reactor vessels
  • Compartments of ships
  • Unventilated room areas
  • Process vessels
  • Tunnels
  • Furnaces
  • Pipelines
  • Silos
  • Boilers
  • Utility vaults
  • Ventilation ducts
  • Conveyers
  • Reasons for Deaths and Injuries from Welding and Cutting in Confined Spaces

  • Fire
  • Electric shock
  • Exposure to hazardous air contaminants
  • Explosion
  • Asphyxiation

  • Actions Required Before Approving Hot Work in a Confined Space

  • Determine if special training or a permit is required to enter the space.
  • Open all covers and secure them from closing.
  • Test atmosphere for:
      (1) suitable oxygen content
      (2) combustibles or reactives
      (3) toxics
        Note: The testing requires special equipment and training.
  • Isolate lines by capping or double blocking and bleeding. Keep vents open and valves leak-free.
  • Lock out/tagout all systems not required during hot work.
  • Provide means for readily turning off power, gas, and other supplies from outside the confined space.
  • Protect or remove any hazardous materials or materials which may become hazardous when exposed to hot work.

  • Required Actions During Hot Work in a Confined Space
  • Continuously ventilate and monitor air to ensure fumes and gases do not exceed safe exposure limits.

  • 29 CFR 1910.252(c) and 1926.353(c) require the use of local exhaust ventilation or supplied air respiratory protection when hot work is performed in a confined space where there is a potential for exposure to fluorine compounds (fluxes and rod coatings), zinc, lead, cadmium, or mercury. When beryllium is present, use both local exhaust and a supplied-air respirator.

  • 29 CFR 1926.353(c) requires the use of local exhaust ventilation or supplied air respiratory protection when hot work is performed in a confined space where there is a potential for exposure to chromium or when Gas Metal Arc Welding is performed on stainless steel.

  • Use NIOSH/MSHA (National Institute for Occupational Safety and Health/Mine Safety and Health Administration) approved breathing device when required by code.

  • Keep unnecessary persons and equipment out of, and away from, the confined space.

  • Do not allow equipment to block exit or rescue efforts. Place as much equipment as possible outside the confined space.

  • Do not enter a confined space unless a watch person, properly equipped and trained for rescue, is outside. Maintain continuous communications with the worker inside.

  • When possible, provide means for readily turning off power, gases, and fuel from inside the confined space, even if outside turn-off means are provided.

  • Resource: AWS Health and Fact Sheet No. 11 - Hot Work in Confined Spaces