Carrying out welding, cutting, or grinding inside confined or enclosed spaces creates a dangerous combination of toxic fumes, oxygen depletion, and fire risk in an area with limited ventilation and escape routes. The accumulated hazards make this one of the highest-risk activities on any construction site. Both a hot works permit and a confined space entry permit are typically required.
Key Hazards
Toxic fume buildup from welding in a poorly ventilated enclosed space
Oxygen depletion from gas shielding and combustion consuming available air
Fire or explosion from flammable residues or gases igniting in the space
Heat stress from working in an enclosed area with high radiant temperatures
Control Measures
Obtain both a hot works permit and a confined space entry permit before work begins.
Provide forced ventilation with fresh air supply at the worker's breathing zone throughout.
Monitor the atmosphere continuously for oxygen, flammable gases, and toxic fumes.
Use fume extraction positioned at the weld point to capture contaminants at source.
Remove or protect all combustible materials inside the space before hot works begin.
Ensure a trained standby person is positioned at the entry point at all times.
Limit the duration of hot works sessions and schedule regular breaks in fresh air.
Keep fire extinguishing equipment inside the space and at the entry point.
Brief all persons on the combined emergency procedures for fire and confined space rescue.
Emergency / Rescue
If the atmosphere alarm sounds or a fire starts inside the space, evacuate immediately. The standby person must not enter without breathing apparatus. Call 999 stating both confined space and fire emergency. Activate the rescue plan.
Remember
Both a hot works permit and a confined space entry permit are required for this work
Forced ventilation must supply fresh air to the worker's breathing zone at all times
Monitor the atmosphere continuously for oxygen, flammable gases, and toxic fumes
A trained standby person must remain at the entry point throughout the operation
Limit session duration and take regular breaks in fresh air to prevent heat stress