Abstract: THE PRESSURE RELIEF VALVE BETWEEN THE ISO STRIPPER AND THE BLOWDOWN LINE FAILED ON SUNDAY, DECEMBER 16. THE FAILED VALVE WAS REMOVED ON THE FOLLOWING TUESDAY. THE BLOWDOWN LINE ON THE ISO STRIPPER SIDE WAS TO BE CLOSED OFF WITH A BLOCK VALVE UNTIL THE RELIEF VALVE COULD BE REPLACED. THERE WAS A POWER OUTAGE AT THE PLATFORMER UNIT WHICH CAUSED THE SULFER UNIT TO SHUT DOWN. A BLOCK VALVE AT THE PLATFORMER WAS OPENED, CAUSING HYDROGEN SULFIDE TO VENT INTO THE BLOWDOWN LINE. HYDROGEN SULFIDE VENTED FROM THE OPEN END OF THE BLOWDOWN LINE AT THE ISO STRIPPER BECAUSE THE BLOCK VALVE HAD NOT BEEN CORRECTLY INSTALLED (NO BLIND WAS INSTALLED). THE LAST TIME THE TWO EMPLOYEES WERE SEEN BEFORE THE ACCIDENT THEY WERE WEARING THEIR AIR MASKS. WHEN THE EMPLOYEES WERE FOUND AFTER THE ACCIDENT, EMPLOYEE #2 HAD HIS MASK PARTIALLY ON AND WAS LOCATED APPROXIMATELY 8 FEET NORTH OF THE WORK AREA. EMPLOYEE #1 WAS ON THE RECEIVER, APPROXIMATELY 15 FEET NORTHWEST OF THE WORK AREA, AND WAS NOT WEARING AN AIR MASK. THE TEMPERATURE ON DAY OF THE ACCIDENT WAS 13 DEGREES F. THERE WAS NO SPOTTER ASSIGNED TO ASSIST THE EMPLOYEES IN THE EVENT OF AN EMERGENCY.