Geismar plant explosion preliminary findings released Geismar plant explosion preliminary findings released Advocate staff report Oct. 04, 2013 Comments A June 13 fire and explosion at the Williams Olefins’ Geismar plant was the result of a vapor cloud released after a reboiler ruptured, according to preliminary findings from an internal investigation into the incident released Thursday. Once the vapor cloud was released, it ignited within seconds from an unknown heat or flame source, according to a news release from the company. Investigations by the Occupational Safety and Health Administration and the U.S. Chemical Safety Board continue. The incident killed two men and injured more than 100 others. The explosion and fire occurred because there was an unexpected hydrocarbon liquid in a reboiler, a specific type of heat exchanger, that was in standby mode. There was heat added to this standby reboiler and because the pressure relief system was isolated from the reboiler, the rupture occurred. Evaluations and testing on metals involved in the explosion continue so Williams Olefins cautioned that their preliminary findings could change.