Case Study: BP Texas City Explosion 23 March 2005
The flammable liquid flowed from the overhead vapor line through the safety relief valves into the collection header for 46 seconds then discharged into the blowdown drum.
Disaster Imminent – Flammable Liquid Flow Out of the Blowdown Stack
Once the blowdown system filled, flammable liquid discharged to the atmosphere from its stack as a geyser and fell to the ground. Shortly after the ISOM operators began troubleshooting the pressure spike, they received, via radio, the first notification that the blowdown drum was overflowing.
The ISOM operators stated they had insufficient time to sound the emergency alarm before the explosion. Hundreds of alarms registered in the computerized control system at 1:20:04 p.m., including the high level alarm on the blowdown drum; the flood of alarms indicates when the explosion occurred. Consequently, ISOM operations personnel did not have sufficient time to assess the situation and sound the emergency warbler alarm prior to the explosion.
Numerous eyewitnesses reported seeing the geyser at the top of the blowdown stack, which they estimated to be approximately 20 feet high. The list of in Unit Startup is provided as an appendix.
The most likely ignition point was an idling diesel pickup truck. This truck was parked about 25 feet from the blowdown drum, and several eyewitnesses reported seeing or hearing the truck’s engine over-revving when the vapor cloud reached it
Fatalities and Injuries
In the explosion, 15 contract employees working in or near the trailers sited between the ISOM and the NDU unit were killed. Autopsy reports revealed that the cause of death for all 15 was blunt force trauma, probably resulting from being struck by structural components of the trailers. Three occupants in the Quality Assurance/Quality Control (QA/QC) trailer perished, and 12 of 20 workers inside the double-wide trailer were killed; the others were seriously injured.
A total of 180 workers at the refinery were injured, 66 seriously enough that they had days away from work, restricted work activity, or medical treatment. The majority