Abstract: Employee #1, an operator, and a coworker, a process operator, were removing coke trap vessel SP-6 from service so that maintenance could be done in a refinery. Employee #1 was being trained by his coworker, who was working on the coke trap as he watched. The coworker had prepared to drain the coke trap by opening the flushing oil line. The procedure called for employees to open the top atmosphere vent to depressurize the trap. The flushing oil line contained cold coker gas oil, which operated at 140 psi. After opening the flushing oil line, the coworker cracked open the bottom 4 in. drain valve to drain condensate or oil that remained in the coke trap. A thick toothpaste-like material came out of the drain. The drain was then closed by the coworker so that it could be cleared of the material. The coworker again cracked open the drain valve and again this thick material came out. The coworker then asked Employee #1 to continue opening the valve while he went to view the drain at a better position. When the valve was about 50 percent open, a sudden expulsion of hot condensate, oil, and coke fines came out of the drain line. The pressure caused the splash guard to lift out of place and hot material sprayed upward toward Employee #1's legs and groin. He was hospitalized with first- and second-degree burns to his lower extremities.