Abstract: At the direction of the maintenance supervisor, Employees #1 and #2 were replacing a collar on top of an 8,800 gallon acid storage tank. The tank had been drained of sulfuric acid but had not been cleaned, and 9 inches of acid sludge remained in the bottom of the tank. Employee #1 used an oxygen-propane torch to begin cutting the collar out of the tank. As he applied the torch, the tank exploded and he was thrown 50 feet to a rooftop southeast of the tank. He died as a result of his injuries. Employee #2, acting as a fire guard, was standing on a catwalk on the east side of the tank. He was killed when he was struck by the tank lid.