A hot work permit is a written authorization for welding, cutting, brazing, grinding, torch-applied roofing or any other work that produces flames, sparks or heat outside a designated hot work area. It forces a check, before the work starts, that combustibles are cleared or protected, fire protection works, and someone is watching for fire during and after the job. Many building fires start hours after the hot work crew has left.
What counts as hot work
- Arc and gas welding, and thermal cutting.
- Brazing and soldering with open flame.
- Grinding and abrasive cutting that throws sparks.
- Torch-applied roofing and thawing pipes with a torch.
- Any other task that could ignite materials or a flammable atmosphere.
A designated shop area built for welding, with non-combustible construction and controls in place, often does not need a permit for each job. Everywhere else, including maintenance work in occupied buildings, should.
The rules behind it
The National Fire Code of Canada, as adopted by each province, includes requirements for hot work. NFPA 51B is the widely used standard for fire prevention during welding, cutting and other hot work, and insurers often require their own permit process. Provincial OHS laws add requirements for hazard assessment, flammable atmospheres, ventilation and worker protection. Check the edition adopted in your province and any conditions in your insurance policy.
Before the permit is issued
The person authorizing hot work should visit the site and confirm:
- Hot work is necessary, and a cold method (mechanical cutting, bolting) is not practical
- Combustibles are removed from around the work, or covered with fire-resistant blankets or shields
- Openings in floors and walls, ducts and conveyors that could carry sparks are covered
- Combustible walls, ceilings and roofs, including hidden spaces, are protected or the work is moved
- Flammable liquids, gases and vapours are absent; atmospheric testing is done where they could be present
- Sprinklers and fire alarm are in service, and any temporary impairment is managed with the building's fire safety plan
- Suitable portable extinguishers are at the work location
- Containers, tanks and piping that held flammables are cleaned and tested, or not worked on
- A trained fire watch is assigned
Work on tanks, vessels and pits may also be confined space work, which needs its own entry permit and atmospheric monitoring.
What the permit records
A typical permit form records the location and description of the work, the date and valid time period, the precautions checked, the names of the person doing the work and the fire watch, and the signature of the person authorizing it. The permit is posted at the work location while the work is under way. It should be valid only for a defined period, often one shift, and re-issued if conditions change.
The fire watch
The fire watch is a trained person whose job is to watch for fire during the work and for a period afterwards. They should:
- Have an extinguisher at hand and know how to use it.
- Know how to raise the alarm and call the fire department.
- Watch both sides of walls and floors where sparks or heat could travel.
- Have authority to stop the work if conditions become unsafe.
- Not be given other tasks that distract them.
Fires often start after the crew leaves. Smouldering material in a wall cavity or roof assembly can take a long time to flare up. NFPA 51B and many insurers require the fire watch to continue for a set period after work ends, followed by further monitoring. Follow the standard and your insurer's terms, and never cut it short.
Closing out
When the fire watch period ends, the area is inspected again, the permit is signed off and filed, and any fire protection that was impaired is confirmed back in service. Keeping completed permits helps with audits, insurance reviews and investigations.
Making the system work
Permits fail when they become paperwork filled in at a desk. Keep the form short and tied to the site walk. Train the people who issue permits, the people who do hot work and the people who stand fire watch. Make sure contractors follow your permit system on your premises, not just their own; see managing contractor safety. Review a sample of completed permits periodically to check that precautions are being verified, not just ticked.
The welding itself carries other hazards too: fumes, UV radiation, burns and electric shock. These need their own controls, including ventilation and respiratory protection where required.
How ehZee can help
ehZee helps building owners and employers set up hot work permit procedures that fit their buildings and fire protection systems, and trains staff on using them. See safety program development and review.
Common questions
Who should sign a hot work permit?
A person designated by the owner or employer, trained in hot work hazards and the permit process, and with authority to refuse or stop work. On construction sites, the prime contractor's procedure usually decides who that is.
Do we need a permit for a small grinding job?
If it is outside a designated hot work area, yes. Grinding sparks travel a long way and can ignite dust, packaging and building materials.