April 8 Explosions and Fire at Giant

CSB to Pursue Full Investigation of April 8 Explosions and Fire at Giant Industries Refinery near Gallup, NM Washington, DC, April 19, 2004 – The U.S. Chemical Safety and Hazard Investigation Board (CSB) has decided to pursue a full root-cause investigation of the recent explosions and fire at the Giant Industries Ciniza gasoline refinery east of Gallup, New Mexico, board member Rixio Medina announced today in Albuquerque. CSB accident investigations typically take 9 to 12 months to complete. The accident on April 8 seriously injured four workers with burns and trauma-related injuries. Two other plant personnel suffered minor injuries fleeing the area of the explosions. All nonessential plant personnel were temporarily evacuated from the refinery. The accident occurred in the refinery’s alkylation unit, which produces highly flammable gasoline components known as “alkylate.” The alkylation unit uses highly toxic hydrofluoric acid as a process catalyst, but investigators have not found evidence of any significant release of the acid. On April 7, workers discovered a malfunction in a pump connected to a distillation column that separates alkylate from lighter hydrocarbons and residual hydrofluoric acid. This steam-powered pump was connected to the bottom of the column where hot alkylate accumulates. The distillation column operates at high temperature and pressure. On the morning of April 8, an operation was undertaken to remove the malfunctioning pump for repairs. An alkylation unit operator attempted to shut off valves connecting the pump to the distillation column and to the pump’s steam supply. The operator and a maintenance mechanic then padlocked the valves in position. Maintenance personnel loosened the pump from its connected piping. A short time later there was a sudden rush of hot alkylate from the open pipe end that led from the distillation column. The alkylate immediately formed a flammable vapor cloud. The release of the liquid and gas made a screeching sound loud enough to be heard at various locations throughout the refinery. A short time after the release began, at about 9 a.m., there was a large explosion as the alkylate vapor cloud ignited, followed by smaller secondary explosions. Injured personnel included the alkylation unit operator, who suffered critical burns; two maintenance mechanics; and a refinery safety officer, who rushed to the scene at the sound of the initial release and was then injured in the explosion. The explosions resulted in a fire that was controlled within an hour by plant personnel, assisted by equipment from a local fire department. Following the accident, investigators examined valves leading to and from the pump. Investigators are focusing on a particular valve that controlled the flow of heated alkylate from the column to the pump. Preliminary information suggests that the position of the valve’s two-foot-long bar-shaped handle may have erroneously indicated to workers that the valve was closed, when the valve was actually open. An open valve would have allowed the release of the heated alkylate that caused the explosion. The valve, piping, and other evidence have now been removed from the alkylation unit and are awaiting further testing and examination by the CSB.