America's worst industrial disaster - Texas City Oil Refinery explosion disaster

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• published: 29 Feb 2016
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The Texas City Refinery explosion occurred on March 23, 2005, when a hydrocarbon vapour cloud exploded at the ISOM isomerization process unit at BP's Texas City refinery in Texas City, Texas, killing 15 workers and injuring more than 170 others. The Texas City Refinery was the second-largest oil refinery in the state, and the third-largest in the United States with an input capacity of 437,000 barrels (69,500 m3) per day as of January 1, 2000. BP acquired the Texas City refinery as part of its merger with Amoco in 1999. BP's own accident investigation report stated that the direct cause of the accident was " heavier–than-air hydrocarbon vapors combusting after coming into contact with an ignition source, probably a running vehicle engine. The hydrocarbons originated from liquid overflow from the F-20 blowdown stack following the operation of the raffinate splitter overpressure protection system caused by overfilling and overheating of the tower contents." Both the BP and the U.S. Chemical Safety and Hazard Investigation Board reports identified numerous technical and organisational failings at the refinery and within corporate BP. In 2011 BP announced that it was selling the refinery as part of its ongoing divestment plan to pay for ongoing compensation claims and remedial activities following the Deepwater Horizon disaster in 2010. The sale of the refinery was completed at the start of 2013 to Marathon Petroleum Corporation for US$2.5 billion. Investigating this pressure spike, the Day Board Operator fully opened the level control valve to the heavy raffinate storage tank and shut off of the gas fueling the furnace, but the raffinate feed into the splitter tower was not shut off. Hot raffinate flowed into the blowdown drum and stack and as it filled, some of the fluid started to flow into the ISOM unit sewer system via a 6-inch (15 cm) pipeline at the base of the blowdown drum. As the blowdown drum and stack filled up, liquid overflowed out of the top of the stack forming a 20-foot (6 m) "geyser" as hot hydrocarbon liquid vented directly into the air. It then ran down the side of the blow-down drum and stack and pooled at the base of the unit. A radio call was received in the control room that hydrocarbons were overflowing from the stack. A pick-up truck, with its engine running, had been parked within 30 feet (9 m) of the blowdown stack; the vapor cloud reached the vehicle, causing the engine to race. The cloud continued to spread across the ISOM plant, across the pipe-rack to the West and into the trailer area. No emergency alarm sounded, and at approximately 1:20 p.m., there was a catastrophic vapor cloud explosion, probably ignited by the overheating truck engine. The blast pressure wave struck the contractor trailers. The force of the explosion sent debris flying, causing fatal blunt force trauma to 15 people in and around the trailers. 180 others were injured. The pressure wave was so powerful it shattered windows off site up to a distance of three-quarters of a mile (1.2 km) away. An area estimated at 200,000 square feet (19,000 m2) was burned.