Washington – The Chemical Safety Board has released an animated video that examines the cause of last year’s ExxonMobil refinery fire, which severely burned four workers in Baton Rouge, LA.
The three-minute video shows how an older, “ill-advised” design involving a support bracket led to the release of about 2,000 pounds of pressurized isobutane on Nov. 22, 2016. CSB stated that the vapor cloud ignited after traveling about 70 feet toward an energized welding machine.
The fire occurred during maintenance in the refinery’s sulfuric acid alkylation unit. Workers could not open an inlet plug valve and get a spare isobutane pump into service because of a faulty gearbox. They removed the gearbox to turn the valve stem manually, but the four bolts on the support bracket also secured a vital pressure-containment piece known as a top-cap.
The valve came apart when a worker attempted to turn the stem with a pipe wrench, releasing the isobutane. That design, which was more than 30 years old, was used in only about 3 percent of the plug valves in the alkylation unit.
CSB’s investigation into the fire is listed as current.
