Abstract: Employee #1, a chemist, Employee #2, and two coworkers were assigned to unplug a feed line to a chemical reactor that was used to form thio-bis as an intermediate product. The plug had occurred on the night shift; the day shift crew began the cleanout operation by flushing the line with toluene after nitrogen pressure failed to free the line. The toluene cleared the line, but the sulfur dichloride still would not feed, so the employees added toluene to the feed tank that was used to feed sulfur dichloride into the reactor. After the first of two 55 gallon drums was added through an air pump Employee #1 went to the tank to feel if it were heating, which would have shown a reaction inside. The blow-out disk released and within one or two seconds the tank exploded, killing Employee #1. Employee #2 was injured by debris and fire. The tank had contained approximately 900 lb of sulfur dichloride and approximately 35 gallons of toluene.