Abstract: At the shift change, employees reported a butane leak that had started approximately 10 minutes before shift change. The shift foreman had initiated an approximately three-hour shut down for the unit, including the F3 drum. At the time of the accident, supervisors were communicating end of shift information. Employee #1, who was starting his regular shift in the area of the leak, was independently trying to hook up a relief line to attempt to divert some of the pressure to the flare line. Employee #2 (who was not assigned to the area) came to assist him. While they were finding fittings and preparing to hook up the diversion line, the butane ignited, causing an intense fire. Employee #1 was killed and Employee #2 was hospitalized for burns.