The Williams Olefins Plant explosion occurred on June 13, 2013 at a petrochemical plant located in Geismar, an unincorporated and largely industrial area 20 miles (32 km) southeast of Baton Rouge, Louisiana. Two workers were killed and 114 injured. The U.S. Occupational Safety and Health Administration (OSHA) and the U.S. Chemical Safety and Hazard Investigation Board (CSB) launched investigations to determine how and why the heat exchanger failed. The Chemical Safety Board concluded that a standby heat exchanger had filled with hydrocarbon. This heat exchanger was isolated from its pressure relief; shortly after the heat exchanger was heated with hot water, the hydrocarbon flashed to vapor, ruptured the heat exchanger, and exploded.