An internal investigation finds the June 13 fire and explosion at the Williams Olefins' Geismar plant was the result of a vapor cloud released after a reboiler ruptured.
The company said in a news release Thursday received by The Advocate that, once the vapor cloud was released, it ignited within seconds from an unknown heat or flame source.
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.
Evaluations and testing on metals involved in the explosion continue so Williams Olefins cautioned that their preliminary findings could change.