Abstract: EMPLOYEE #1 WAS ATTEMPTING TO LIGHT A PROCESS HEATER (SIMILAR TO A LARGE FURNACE) AFTER COMPLETION OF A MAINTENANCE SHUT-DOWN. THE FUEL LINE HAD BEEN LEFT OPEN AND THE PILOT FUEL LINE LEFT CLOSED. THE EMPLOYEE WAS UNDER THE PLENUM, USING AN ACETYLENE TORCH, WHEN THE EXPLOSION OCCURED. EMPLOYEE #2 WAS SEVERAL FEET AWAY. EMPLOYEE #1 WAS STRUCK BY THE FLOOR OF THE PLENUM. THE CORONER'S REPORT STATED THAT THE CAUSE OF DEATH WAS A FRACTURE OF THE SKULL. EMPLOYEE #2 SUFFERED MINOR BURNS OF THE THROAT. CONTRIBUTING FACTORS: THERE WAS NO AVAILABLE METHOD OF "PROVING" THE PILOT. FUEL GAS WAS ALLOWED THROUGH THE LINES WITHOUT FIRST INSURING THAT THERE WAS A PILOT LIGHT.