Hot Work & Fire Prevention
Welding, Cutting
& Fire Hazards
& Fire Hazards
OSHA 1926.352 · NFPA 51B · NYC FC §105.6 · 35-Foot Clearance · 60-Min Fire Watch
Welding and cutting sparks travel farther than most workers expect — hot slag has been found igniting fires over 35 feet from a welding arc and falling through floor penetrations to levels below. On NYC construction sites with multiple trades working simultaneously, a welding fire can spread through an unfinished building in minutes.
Spark Travel — The Distances That Surprise People
- Hot slag from cutting operations can travel horizontally 35+ feet and remain hot enough to ignite paper, cardboard, or foam for several seconds after landing
- Sparks travel through floor openings, open stud bays, HVAC penetrations, and around corners — they go where you don't expect
- UV radiation from arc welding can ignite flammable vapors at a distance without visible sparks — never weld near open containers of solvent
- Welding on steel embedded in concrete: concrete conducts heat farther than you think and can char wood on the other side
The Hot Work Clearance Zone
- Remove all combustibles within 35 feet of the welding/cutting location — move them or cover with fire blankets
- Seal all floor openings, wall penetrations, and gaps within 35 feet with fire-resistant material
- Wet down wooden floors and formwork within the clearance zone when they cannot be removed
- Post one worker as Fire Watch with unobstructed sight lines to the entire work area and all adjacent spaces
- Fire Watch continues for 60 minutes after the last arc or flame — the fire may not start immediately
FDNY Hot Work Permit Requirements
- FDNY Hot Work Permit required before any welding or cutting — no exceptions, regardless of duration
- Permit must be displayed at the work location, not kept in the field office
- CSFSM issues and logs all hot work permits daily in PL-002
- Expired permit found during FDNY inspection = immediate stop-work order + $5,000+ penalty
Discussion Questions
- How far can welding slag travel horizontally, and what does this mean for material storage near your work area?
- You finish welding at 2:00 PM. Fire Watch can stop at what time, and what must they be doing during that period?
- There is a stack of cardboard boxes 30 feet from your welding location. Do you need to move them? Why?
- Who issues the FDNY Hot Work Permit on this site and where must it be located during the work?
Sign-Off
Project Address
Date
Time
Foreman / Supervisor
SSM / SSC Name & License No.
Worker Attendance
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