Abstract: On March 10, 2009, Employee #1, a foreman, Employee #2, an engineer, Employee #3, a pipefitter, Employee #4, a welder, Employee #5, a welder's helper, Employee #6 a fire watch, and Employee #7, an equipment operator, were working at a pipeline/transportation facility in conjunction with an expansion, cutting an existing 4-in. pipeline and welding a new section into the existing pipeline. The pipeline was connected to a 4,500-gallon sump tank that contained 1-ft. of crude oil. Employees #4, #5, and #6 were standing in an excavation that measured 19-ft by 24-ft by 6-ft deep. Employee #7 was still sitting in the excavator after he dug the excavation. Employee #1, #2, and #3 were standing behind a 30-in. pipe that ran parallel to the excavation and 7 ft in front of the sump tank. A mud plug consisting of bentonite had been placed into the 4-in. pipe connected to the sump tank to isolate the hydrocarbon vapors in the sump tank from the hot work. Employee #4 positioned the oxygen/acetylene cutting torch attached to a hand cranked beveling machine approximately 4 in. from the end of the 4-in. pipe. Employee #4 made one pass around the area to be beveled using the oxygen/acetylene from the torch to remove the paint from the pipe. Once the paint was removed from the 4-in. pipe, Employee #4 turned off the oxygen on the torch and positioned the oxygen/acetylene torch to commence the beveling cut on the 4-in. pipe using only the acetylene. Employee #4 heated the surface of the pipe until it was red hot and then turned on the oxygen to create the right mixture to initiate the cut. At this time, the sump tank containing the crude oil exploded blowing the 9-ft. by 2-in. metal top off the sump tank. Employees #4, #5, and #6 were not injured by the explosion or the fire. Employee #7 jumped off the excavator because it was on fire and sustained a torn bicep to his right arm. Employee # 3 was hospitalized, where he was treated for second and third degree burns to the face and back. Employee # 2 was hospitalized, where he was treated for second and third degree burns to the back. Employee # 1 was killed, when he turned to run and fell into the burning sump tank.