Abstract: On April 23, 1991, Employee #1, of R. C. Collett Asphalt, was on duty when the type of asphalt mix was being changed. This required the oil be drained from the system back into the heated storage tank. The valves on the alternate tank were then opened and the return pipe valve was double-checked. The pumping system to the mixer had one pump to send the oil from the tank and another to meter the oil to the mixer. Between the two pumps was a return-bypass pipeline with a surge tank mounted near the first pump. The pump system had no pressure relief valve. When the pumping began, the return pipe valve at the tank was not preventing the surplus oil from returning to the storage tank. This resulted in pressure building up in the return pipeline and surge tank, which was not designed as a pressure tank. After several minutes, the pressure in the surge tank exceeded its capacity and the tank burst, spraying hot oil over Employee #1. He suffered first- and second-degree burns on his face and chest. He would have sustained more severe burns if the oil in the surge tank had not cooled to below 200 degrees F.