WLD/Hazards/TBT-WLD-011

Welding in Confined Spaces

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Welding in Confined Spaces

Toolbox Talk Record

Ref: TBT-WLD-011  |  Issue: 1  |  Date: March 2026
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What?

  • Welding in confined spaces combines the hazards of hot works with the dangers of confined space working.
  • Welding consumes oxygen and produces toxic fumes that accumulate rapidly in enclosed volumes.
  • Shielding gases such as argon and CO2 displace oxygen and can reduce levels to dangerous concentrations.
  • Confined space welding requires both a hot works permit and a confined space entry permit.
  • Forced mechanical ventilation must supply fresh air to the welder and extract fumes continuously.
  • Portable gas monitors must be worn by the welder and monitored by the top person at all times.
  • The fire risk is amplified — sparks and spatter in a confined space ignite residues quickly.
  • Electric shock risk increases in confined spaces due to contact with conductive metal surfaces.
  • Emergency rescue procedures must account for the welder wearing equipment in a restricted space.
  • Only the minimum amount of shielding gas and filler materials should be taken into the space.

Why?

Oxygen depletionWelding processes and shielding gases deplete oxygen in confined spaces, causing unconsciousness and death within minutes.
Toxic fume build-upWelding fumes accumulate to dangerous concentrations far faster in enclosed volumes than in open air.
Combined hazardsThe simultaneous confined space, fire, fume, and electrical hazards make this one of the highest-risk welding activities.
Do Don't
  • Obtain both a confined space permit and hot works permit before starting
  • Provide continuous forced ventilation supplying fresh air and extracting fumes
  • Wear a personal gas monitor and ensure the top person monitors readings
  • Use 110V or battery-powered welding equipment to reduce electric shock risk
  • Keep shielding gas cylinders outside the confined space with hoses fed in
  • Maintain continuous communication with the standby person at the entry point
  • Position a fire extinguisher at the entry point ready for immediate use
  • Ensure the rescue plan accounts for the welder and all equipment in the space
  • Take regular breaks outside the space to recover from heat and fume exposure
  • Remove all welding equipment from the space during breaks and at completion
  • DON'T weld in a confined space without both required permits in place
  • DON'T rely on natural ventilation alone — forced extraction is essential
  • DON'T take gas cylinders inside the confined space under any circumstances
  • DON'T continue welding if the gas monitor alarm sounds — exit immediately
  • DON'T use mains voltage welding equipment inside confined spaces
  • DON'T leave the standby person's position unattended during the welding operation
  • DON'T ignore signs of dizziness, headache, or nausea while welding inside
  • DON'T start welding before confirming ventilation is operating and effective
  • DON'T allow combustible residues to remain in the space before hot works begin
  • DON'T re-enter after evacuation until the atmosphere has been re-tested and cleared

See also: Welding Safety Awareness (Comprehensive) | Hot Works in Confined Spaces
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