HOT/General/TBT-HOT-009

Hot Works in Confined Spaces

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Hot works in confined spaces combine fire, fume, oxygen depletion, and explosion risks in an enclosed area.
Welding, cutting, and grinding consume oxygen rapidly, reducing breathable air in the confined space.
Flammable vapours and gases in confined spaces can be ignited by sparks, creating instant explosion.
Welding fume concentration in confined spaces is far higher than open-air operations due to poor ventilation.
Both a hot works permit and a confined space entry permit are required for this combined high-risk activity.
Forced ventilation must supply fresh air and extract fume continuously throughout the hot works operation.
Continuous atmospheric monitoring for oxygen, flammable gas, and toxic fume must be maintained.
A fire watch and a top man must both be present; these must be separate dedicated persons.
The Confined Spaces Regulations 1997 and the Joint Fire Code both apply to hot works in confined spaces.
Rescue equipment must be in place and the rescue plan must account for fire and atmosphere hazards.

Explosion risk	Sparks from hot works ignite flammable gas or vapour in a confined space, causing fatal blast injuries and burns.
Oxygen depletion	Welding and cutting consume oxygen rapidly in enclosed volumes, causing unconsciousness and asphyxiation within minutes.
Fume concentration	Welding fume in a confined space reaches toxic levels far faster than in open air, causing acute poisoning.

Don't

Obtain both a hot works permit and confined space entry permit before starting.
Provide continuous forced ventilation supplying fresh air and extracting fume.
Monitor oxygen, flammable gas, and toxic fume levels continuously during the work.
Appoint separate persons as fire watch and top man; never combine these roles.
Test the atmosphere before, during, and after hot works in the confined space.
Have rescue equipment in place that accounts for fire and atmosphere emergencies.
Position a fire extinguisher inside the space within reach of the hot works operator.
Remove all flammable materials and residues from the confined space before starting.
Continue the fire watch for 60 minutes after hot works are completed.
Brief the entire team on the combined risks and the emergency rescue plan.

DON'T start hot works in a confined space without both permits signed and issued.
DON'T weld or cut in a confined space without forced ventilation running.
DON'T combine the fire watch and top man roles into one person.
DON'T ignore atmospheric monitoring alarms; evacuate the space immediately.
DON'T use oxy-fuel equipment in a confined space without extreme caution and controls.
DON'T store gas cylinders inside the confined space; keep them outside.
DON'T leave hot works fume extraction off because it feels draughty.
DON'T assume the atmosphere is safe after hot works; test before re-entering.
DON'T end the fire watch early; maintain it for the full 60 minutes.
DON'T proceed if any residual flammable material remains inside the space.

See also: Confined Space Entry Procedures | Hot Works Permit Requirements

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