At approximately 1:20 p.m. on Wednesday, March 23, 2005 a series of explosions and fire occurred at the BP Texas City oil refinery during the start-up of an isomerization (ISOM) process unit. Fifteen workers were killed and about 170 other people were injured. Many of those killed were working in or around office trailers located near a blowdown drum and stack open to the atmosphere. The U.S. Chemical Safety and Hazard Investigation Board (CSB) found that because of problems that began during the ISOM process unit start-up, a sudden, geyser-like release of flammable hydrocarbon liquid and vapor discharged from the atmospheric vent stack. This release created a flammable vapor cloud, which ignited, causing as many as five explosions and fire in and around the ISOM unit. CSB identified multiple possible ignition sources in and around the blowdown drum area, including idling vehicles; however, the exact ignition source remains unknown.
CSB deployed a team of investigators to BP Texas City to conduct a root-cause investigation immediately after the incident. This team examined blast patterns to determine the explosion origin; reviewed the design of the isomerization unit equipment; and examined plant safety and operating procedures, past accidents, maintenance procedures, and oversight and inspection. Investigators also reviewed the adequacy of applicable regulations and industry standards for the placement of temporary structures such as trailers in refineries. This article presents the preliminary findings from the CSB investigative team regarding the technical and underlying causes of the incident and discusses three urgent recommendations issued by the CSB stemming from the BP incident. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006