(93a) Flammable Vapor Explosion At Dupont Yerkes Facility

This case study examines a November 9, 2010, explosion at an E.I. duPont de Nemours and Co. Inc., Yerkes chemical plant in Buffalo, New York when a contract welder and foreman were repairing the agitator support atop an atmospheric storage tank containing flammable vinyl fluoride. The welder died instantly from blunt force trauma, and the foreman received first-degree burns and minor injuries. The explosion blew most of the top off the tank. The top and agitator assembly hung over the side of the tank supported only by a 2-foot section of the top (cover photo). The explosion caused minor overpressure damage in the tank farm area and the adjacent production building.

The U.S. Chemical Safety Board (CSB) determined that flammable vinyl fluoride (VF) vapor from interconnected, in-service process tanks flowed undetected into the tank and ignited when the welder was repairing the agitator support assembly. In February 2010, the CSB issued a “Hot Work Safety Bulletin” that summarized 11 similar fatal incidents. Like the incidents described in the bulletin, this was another example of improperly monitored hot work activities involving flammable conditions inside a container.