Controlling the Spark: Essential Fire Prevention in Hot Work Zones

Welding, cutting, grinding and brazing all throw sparks and hot metal, and they travel further than most people expect. They bounce, roll and drop through gratings and gaps into places nobody thought to check. If there's anything flammable within reach, including vapour leaking from equipment that "should" be sealed, a routine repair can become a fire or an explosion.

The rule for hot work is: control the area before you strike an arc or light a torch.

What that looks like on the job

• Work under a hot work permit that considers what's around, above, below and behind the job, not just the job itself.
• Remove or protect anything that can burn, and cover gaps and drains where sparks could fall.
• Test for flammable gas before you start and, where vapours could build up, keep monitoring while you work.
• Provide a dedicated fire watch where required, with suitable firefighting equipment, during the work and for the monitoring period your procedure sets afterwards, because smouldering fires can take a while to show.
• Ask whether hot work is necessary at all. Cold cutting or bolting can sometimes do the same job without the ignition source.

Real-World Impact

In July 2001, at the Motiva refinery in Delaware City, Delaware, a contract crew was repairing a catwalk above a farm of sulfuric acid storage tanks. A spark from their hot work ignited flammable vapours in one of the tanks below, which had holes in its roof and shell from corrosion. The tank exploded and collapsed. One worker was killed and eight others were injured, and more than a million gallons of acid were released, some of it reaching the Delaware River. The Chemical Safety Board concluded that hot work should never have been authorised above a corroded tank known to contain flammable vapours.

Source: U.S. Chemical Safety and Hazard Investigation Board (CSB), Motiva Enterprises investigation (2002)

Reflective Questions

• Before your last hot work job, did anyone check what was below you, not just around you?
• Is our fire watch genuinely watching, or doing three other tasks at the same time?
• Which of our hot work jobs could be done with a cold method instead?