On November 22, 2016, an isobutane release and fire seriously injured four workers in the sulfuric acid alkylation unit at ExxonMobil’s Baton Rouge refinery.  Recently, the U.S. Chemical Safety Board determined that an “insufficient safety culture”, which allowed maintenance to be done without proper instructions and training, caused the fire.

During removal of an inoperable gearbox on a plug valve, an employee removed critical bolts securing a pressure-retaining component of the valve which came apart and released isobutane which formed a vapor cloud.  The isobutane ignited within half a minute, causing the fire and burning the workers who were unable to exit the vapor cloud in time.

The Chemical Safety Board’s report stated that updating older valves to newer ones with safer designs would have prevented the fire.  OSHA issued $164,775 in fines to ExxonMobil in connection with the November 2016 fire. It issued nine violations, including a repeat citation for failure to follow recognized engineering practices for process safety management inspection and testing procedures. A serious violation was also issued for failure to complete written safety information before conducting any process safety hazard analysis required under OSHA’s standard.