Purpose
Hot work (welding, cutting, grinding, brazing, soldering, and any operation producing sparks, flame, or heat) is the leading cause of fire in buildings under maintenance or construction. This SOP establishes the controls required before, during, and after hot work in occupied buildings.
Applicable Standards
- NFPA 51B — Standard for Fire Prevention During Welding, Cutting, and Other Hot Work
- OSHA 29 CFR 1910.252 — Welding, Cutting, and Brazing
- ISO 45001 — Occupational Health and Safety
- BNBC 2020 Part 4 — Fire Protection
Activities Classified as Hot Work
- Arc welding, MIG/MAG welding, TIG welding
- Oxy-acetylene cutting and brazing
- Angle grinding, disc cutting
- Soldering (above 400 degrees C)
- Bitumen/tar heating and application
- Heat shrinking with open flame
- Any operation that produces sparks, open flame, or temperatures capable of igniting combustibles
Pre-Work Requirements
| Requirement | Detail | Responsible |
|---|---|---|
| Hot work permit | Issued by authorised person, valid for maximum 8 hours, specific to location and task | Permit Issuer |
| Risk assessment | Site-specific, identifying combustibles, fire spread paths, escape routes | Performing Authority |
| Combustible clearance | Remove all combustibles within 11 metres (35 feet) radius. If cannot be removed, cover with fire-resistant blankets. | Performing Authority |
| Floor/wall openings | Seal or cover all openings within 11m where sparks could travel to other areas | Performing Authority |
| Fire detection | Isolate specific detector heads (document which ones). DO NOT isolate entire zones. | FM/Fire System Engineer |
| Sprinkler impairment | If sprinklers must be impaired, notify insurer and fire monitoring company | FM Manager |
| Fire extinguisher | Minimum one appropriate extinguisher at the work location (ABC dry chemical or CO2) | Fire Watch |
| Fire watch assigned | Dedicated person whose sole job is fire watch. They must not perform any other task. | Permit Issuer |
During Hot Work
- Fire watch must maintain continuous observation of the work area and adjacent areas (above, below, behind walls).
- Fire watch must have fire extinguisher immediately available and know how to use it.
- Fire watch must have means to raise the alarm (radio, phone).
- Welding screens must protect nearby workers from UV radiation and sparks.
- Ventilation must be adequate for fume extraction (especially in enclosed spaces).
- PPE: welding helmet/goggles, fire-resistant gloves, leather apron, safety boots.
Post-Work Fire Watch
This is the most critical control. Most hot work fires start AFTER the work is completed, when no one is watching.
| Standard | Post-work fire watch duration |
|---|---|
| NFPA 51B | Minimum 60 minutes after hot work ceases |
| Insurance (FM Global) | 60 minutes minimum, many require 120 minutes |
| Best practice for buildings | 60 minutes minimum, 120 minutes for concealed spaces |
During post-work fire watch, the fire watch person inspects the work area and all adjacent areas (above, below, behind walls and ceilings) for signs of smouldering, smoke, or heat.
Detector and Sprinkler Reinstatement
- Isolated detectors must be reinstated immediately after post-work fire watch is complete.
- Sprinkler impairment must be restored immediately.
- Fire alarm monitoring company must be notified of reinstatement.
- FM Manager must verify reinstatement is logged.
References
Insights & Guidance
- Hot work is the leading cause of fire during building maintenance. Every hot work activity requires a permit.
- Remove all combustibles within 11 metres (35 feet). If they cannot be removed, cover with fire-resistant blankets.
- Dedicated fire watch person during work AND for 60 minutes minimum after work stops. This is the most critical control.
- Isolate specific detector heads only (not entire zones). Reinstate immediately after post-work fire watch.
- Most hot work fires start AFTER the work is completed. Post-work fire watch is not optional.
Unpermitted and uncontrolled hot work is the number one cause of fire during building maintenance worldwide. A single spark from grinding can smoulder for hours before igniting a fire in concealed spaces.
- No fire watch — sparks ignite combustibles after the welder has left.
- Entire zone isolated — a real fire in another part of the zone goes undetected.
- Combustibles not cleared — sparks travel up to 11 metres and through floor/wall openings.
- Completed hot work permits with fire watch sign-off
- Detector isolation and reinstatement log
- Pre-work inspection checklist (combustible clearance)
- Fire watch person training records
- Is there a dedicated fire watch person during hot work?
- Are combustibles cleared or covered within 11m?
- Is a fire extinguisher at the work location?
- How long is fire watch maintained after hot work stops?
- Who is authorised to issue hot work permits?
- How are detector isolations tracked and reinstated?
- Fire risk assessment — fire safety consultant.
- Sprinkler impairment protocol — insurer and fire engineer.
- Welding safety training — certified welding body.