Employee #4 was cleaning the #6 chemical reactor on July 19, 1990, with a flammable mixture of solvents when the reactor burst its rupture disc and the mixture was expelled into the plant. The solvent ignited and the vapor cloud explosion resulted in the plant's 43 employees being injured by flying debris and/or being thrown by the force of the explosion. Employee #4 eventually died from his burns. Employee #1, a maintenance employee, was moving away from the area when he was struck in the head and killed by debris flung during the explosion.
Employees #3, #6, #7, #8, #9, #16, and #19 were located in the manufacturing offices in Building 4, about 75 ft south of the reactor. Employees #2, #10, #11, #12, #14, #15, and #17 all worked in Building G, 50 to 75 ft southwest of the reactor and were leaving when the explosion either threw debris at them or threw their bodies onto equipment or debris. Employee #5 was in the same building as the reactor and was thrown down by the explosion, sustaining burns and crushing injuries. Employee #13 sprained his knee while moving from the break room to the courtyard, about 100 ft southeast of the reactor. Employee #18 suffered a sprained left thigh and a bruised shoulder.
It appeared that the reactor was not vented to a safe location and had primitive temperature controls, and the company did not enforce the mandatory attendance of operators at the reactors during operation. All of these factors, including minimal operating procedures (none specifically for cleaning), led to the explosion and the resulting extensive injuries and property damage.
Source:Osha.gov
