Hot Work Ignition of Trapped Flammable Vapor

Welding, cutting, or grinding is done on or near a tank that still holds flammable residue or vapor. The sparks ignite the vapor space and the tank or piping ruptures.

CSB's Hot Work Safety Bulletin (2010) identified 60+ fatalities since 1990 from hot-work fires/explosions on or near tanks, and mandates hazard assessment plus atmosphere monitoring with a calibrated combustible-gas detector before and during work (CSB Hot Work Bulletin).

1. Consider alternatives to hot work first.
2. Do a hazard assessment; isolate/clean the tank and connected lines.
3. Gas-test with a calibrated detector — verify well below LEL.
4. Monitor continuously during the work, not just at the start.
5. Stop work the moment readings drift upward.

CSB counts 60+ hot-work fatalities since 1990 (~1.7/yr in its incident set) (CSB Hot Work Bulletin 2010); U.S. fire departments responded to an average 4,630 structure fires involving hot work per year (2013–2017) (NFPA via BHHC Safety Center,…

Tank/piping rupture and deflagration; multiple-fatality events are typical of the class — 3 killed at PCA Tomahawk alone (CSB).