Abstract: Employees of a tank-cleaning contractor were removing the cover from the hatchway of a 10,000-gallon underground storage tank. The tank contained approximately 2,200 gallons of flammable liquid with a 50-degree-Farenheit flashpoint. One of the employees entered a 4-foot-deep concrete manhole to access the hatch cover. He took an oxyacetylene cutting torch into the manhole to cut heads off of the bolts that secured the cover. He had cut between four and seven bolt heads when the tank exploded. He was propelled from the manhole and over an adjacent building. The employee was found deceased approximately 120 feet from the manhole.