Abstract: Employee #1 was at an establishment that repairs bulk fuel transport trucks, repairing a small leak on the rear bulkhead of an aluminum tanker that had last contained an asphalt emulsion. Employee #4 was assigned as his helper. Other welders recommended opening and venting the tanker and then entering the tank to repair the leak from the inside. The company had no specific procedures for "safing" asphalt tankers, and Employee #1 apparently chose to try to repair the leak from the outside. Once the tanker was backed into the workbay, Employee #1 attempted the repair with an arc welder. The repair failed because of product contamination around the leak. Employee #1 then lowered the tanker at the front to force the remaining product to the front and away from the leak, and used an oxygen/acetylene torch in an attempt to melt the asphalt emulsion away from the leak, but did not open the top hatches and vent the tank. An explosion occurred and Employee #1 suffered fatal head injuries. Employee #4, who was next to the tanker, was knocked to the floor and suffered from ringing in the ear, dizziness, and headaches from inhalation of asphalt fumes and smoke. Employee #2 sustained bruises to his ribcage when thrown into a work bench by the explosion. Employee #3 sprained his left knee when the explosion knocked him from the top of a nearby tanker. The building was heavily damaged and the tanker was destroyed. Causal factors include: a lack of established procedures for safing an asphalt tanker before cutting/welding; inadequate supervision of welding operations; absence of employee hazard training and unsafe work practices.