Abstract: Employees #1, the project engineer, and #2, a maintenance technician, were removing a drain plug on an inline filter (strainer) on a hot oil pump system. Valves were closed but not locked out and the pump was shut off. The oil was under pressure (30 to 40 psig) and at 450 degrees F. The plug was being slowly backed out over several minutes. Employees #1 and #2 reported that the plug suddenly popped out and hot oil was emitted, spraying Employee #1 primarily and, Employee #1 to a lesser extent. Employee #2 was able to run out of the area and call coworkers to help. The Forest Grove Fire Department was called and responded. Employees #1 and #2 were transported to Emmanuel Hospital. Employee #2 chose to be treated and released; Employee #1, who was more seriously burned, was admitted and treated in the burn unit. Given the amount of oil that sprayed out of the filter, it appears that at least one of the isolation valves was not completely closed. This incident occurred in an area that had the potential for a flammable atmosphere had the system been in production mode. Employee #1 was an employee of a foreign employer which was a parent company to the employer.