UNITED STATES
DEPARTMENT OF LABOR

Abstract: At 6:45 p.m. on September 20, 2022, the south area units of the refinery were ex periencing process upset conditions, including lifting pressure safety valves an d loss of pump arounds on the crude tower. Due to an incident earlier in the day , the NT/Sat gas unit and Coker gas plant were not in normal operating condition s. During work to troubleshoot and provide stability to the process units, the o pening of a flow control valve to the absorber stripper tower in the Coker gas p lant resulted in naphtha to flow downstream, eventually filling the TIU fuel gas mix drum with naphtha. This led to liquid in the refinery fuel gas system, whic h initiated the shutting down of some operating units. During outside employee r esponse to the high liquid level in the TIU fuel gas mix drum, naphtha was relea sed into the atmosphere, forming a flammable vapor cloud at ground level and in the oily water sewer at the refinery. At approximately 6:47 pm, the vapor cloud ignited at/near the TIU fuel gas mix drum, possibly due to nearby fired heaters, in the crude unit. Both of the outside employees who responded to the high liqu id levels were severely burned in the explosion. Both of the employees died due to their burn injuries in the early morning of September 21, 2022.