What is hot work?

Where it happens on ordinary properties

Not only in fabrication shops. A contractor cutting bolts on a rooftop unit at an apartment community, a plumber sweating pipe in a hotel mechanical room, a crew torching down a roof on a strip center, a millwright grinding a bracket in a warehouse, a steel erector welding on a high-rise frame, a maintenance tech soldering in a plenum. Each throws sparks and slag that travel well beyond the work and lodge in insulation, dust, cardboard or the void behind a wall, where they smolder before flaming, often after the crew has left.

Why it is controlled

Because the fire starts later and elsewhere. OSHA’s 29 CFR 1910.252(a)(2)(iii) requires a fire watch during hot work where combustibles are within 35 feet, or further away but easily ignited, or exposed through wall or floor openings, and requires the watch to be maintained at least 30 minutes after the work ends. NFPA 51B, which most permit systems follow, requires the permit, the inspection of the area and a watch for at least an hour after completion. The permit is the paper; the watch is the person.

What the fire watch does

Stays where the sparks land, which may be the floor below a deck or the far side of a wall. Keeps extinguishers within reach and knows how to use them. Keeps the area clear of new combustibles and of people. Stays for the post-work period, when most hot work fires actually start, walking the area and the spaces heat could have reached. Logs it all for the permit file.

Booking a watch

Contractors who cannot spare a trained crew member contract the watch; the hot work fire watch page explains how, and the hot work fire watch checklist lists the checks in order.