Abstract: Employee #1 had been welding pipe joints on the ground while his helper was grinding the pipes. He was told by the construction supervisor to weld an extension onto a vent tube holder on a 500 barrel empty storage tank. His supervisor had been told of the project. Employee #1 climbed to the top of the tank with the extension and started to weld the section in place with an arc welder. Employee #2, the gang pusher, had been working on top of the 500 barrel water tank installing 2 1/2 in. lines over to the empty storage tank, and had just gotten on top of the empty tank to take a measurement. An explosion occurred and the empty tank flew up and landed on its side. Employees #1 and #2 were thrown off. Employee #1 landed on the ground, possibly breaking his neck, and died on impact. Employee #2 landed on his right side, breaking his right arm and leg, ankle, and left wrist. A 4 in. vent line filtered from oil and water tanks.