Abstract: Employee #1 was assisting a fleet manager in introducing compressed air into a steel above-ground horizontal fuel storage tank. They were testing for leaks before the tank was returned to service.The tank was pressurized to 15 psi and left overnight; during that time all pressure leaked out. The next day Employee #1 and the fleet manager pressurized the tank to 10 psi in order to perform a soap and air leak test. Employee #1 was passing in front of the tank end when the welds failed, blowing off the tank's end and propelling the employee 65 feet. Employee #1 suffered a closed head injury resulting in partial brain damage; a broken left arm; broken right pelvis; perirenal and periduodenal hematomas; and lacerations.