EGray Iron Foundry
In February 1999, a dust explosion occurred in the shell mold building of a gray iron foundry in Massachusetts killing three workers and seriously injuring nine other workers. In the shell mold process, a mixture of sand and phenolic resin was heated to form molds for casting iron parts. A team of engineers from Exponent’s Massachusetts and California offices determined that the explosion was fueled by phenolic resin dust that had accumulated in the ductwork of an odor control system and on elevated surfaces throughout the building. During cleaning and maintenance at the time of a shift change, a small fireball was created in one shell mold station and sucked into the odor control system. This caused a dust deflagration that propagated through the ductwork and spread to other shell mold stations. This deflagration dislodged additional phenolic resin dust that had collected on surfaces throughout the building, fueling additional explosions. Exponent found that the foundry was generally unaware of the dust explosion hazard of the phenolic resin and had not complied with the applicable standards for the prevention of dust explosions. It was determined that the manufacturer of the phenolic resin powder had failed to adequately communicate the dust explosion hazard of their product to the foundry.