Abstract: Employee #1 was welding a tank holding a class II combustible. He was standing on either the front side of the tank or on the ladder by the tank when the tank exploded. Employee #1 suffered fatal head injuries when he was struck by part of the tank and hurled into a concrete wall. The tank, which was shop-made from a cement truck mixer drum, was manufactured as an atmospheric tank that the company turned into a low pressure tank. The 8 yard mixer drum, model #232, was manufactured by Rexnord, Inc., Milwaukee, WI, and the valve, model #I-19816, was manufactured by Bendix-Westinghouse. The class II combustible was Thoco 50 truck wax, a blend of 80 percent kerosene, 18 1/2 percent Tenneco golden oil, and 1 1/2 percent Indopol. The low pressure tank was not built in accordance with acceptable standards (i.e., there were no vents or emergency relief devices).