WLD/Hazards/TBT-WLD-011

Welding in Confined Spaces

Welding & Fabrication › Hazards › Welding in Confined Spaces

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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.

Oxygen depletion	Welding processes and shielding gases deplete oxygen in confined spaces, causing unconsciousness and death within minutes.
Toxic fume build-up	Welding fumes accumulate to dangerous concentrations far faster in enclosed volumes than in open air.
Combined hazards	The simultaneous confined space, fire, fume, and electrical hazards make this one of the highest-risk welding activities.

Don't

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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