Abstract: AT APPROXIMATEKY 5 PM ON MARCH 20, 1986, EMPLOYEE #1 WAS USING A TRUCK MOUNTED HOT OIL UNIT TO PUMP HOT (260 DEGREES) CRUDE OIL, UNDER ABOUT 600 PSI PRESSURE, INTO THE CASING HEAD OF AN OIL AND GAS PRODUCING WELL. THE HOT OIL WAS BEING USED TO MELT PARAFFIN IN THE WELL. AS EMPLOYEE #1 WAS ENGAGED IN THIS OPERATION, ANOTHER EMPLOYEE (EMPLOYEE #2) ARRIVED WITH ANOTHER HOT OIL UNIT AND PARKED ADJACENT TO THE HOT OIL UNIT IN USE. SUDDENLY A DISCHARGE HOSE RUPTURED AND HOT OIL STARTED FLOWING BACK FROM THE WELL. THE HOT OIL WAS IGNITED BY FLAMES FROM THE FIRE BOX OF THE HEATER ON THE UNIT IN USE. EMPLOYEE #1 WAS BURNED OVER 97% OF HIS BODY. EMPLOYEE #2 RECEIVED ONLY MINOR BURNS ON HIS FINGERS WHICH HE SUFFERED WHEN HE WENT TO ASSIST EMPLOYEE #1. BOTH EMPLOYEES WERE TRANSPORTED TO THE HOSPITAL. EMPLOYEE #2 WAS RELEASED THE SAME DAY, BUT EMPLOYEE #1 DIED ON APRIL 17TH AS A RESULT OF THE SEVERE BURNS HE SUFFERED. CAUSAL FACTORS: THE HOT OIL UNIT HAD NO PRESSURE RELIEF DEVICE ON THE PISTON PUMP; THERE WAS NO CHECK VALVE IN THE OIL LINE TO PREVENT BACK FLOW FROM THE WELL; THE DISCHARGE LINE WAS NOT PRESSURE TESTED BEFORE USE.