Abstract: At approximately 12:30 a.m. on May 17, 1990, an explosion and flash fire occurred on the 51 ft 4 in. high Tuyere service platform at the L blast furnace at Bethlehem Steel Corp. Although the natural gas had been turned off, it apparently leaked from a main valve on one of the 35 2 in. diameter downleg pipes that encircled the furnace. Employee #1 was sitting on a parked forklift truck below the gas downleg pipe. He was killed. Employees #2 through #9 were hospitalized. The explosion may have occurred from various sources, including welding sparks, a forklift motor, etc. The cause of the downleg pipe's disconnection from the pipe is unknown.