On June 24, 2005, fire and explosions swept through the Praxair Distribution, Inc., gas cylinder filling and distribution center in St. Louis, Missouri. The accident occurred when gas released by a pressure relief valve on a propylene cylinder ignited.
The U.S. Chemical Safety Board (CSB) investigators noted the accident occurred on a hot summer day with a high temperature of 97 degrees F in St. Louis. At Praxair, cylinders were stored in the open on asphalt, which radiated heat from the direct sunlight, raising the temperatures and pressure of the gas inside the cylinders. At approximately 3:20 p.m., a propylene cylinder pressure relief valve began venting. CSB investigators believe static electricity, created by escaping vapor and liquid, most likely ignited the leaking propylene.
The CSB issued Safety Bulletin listing several best practices for cylinder storage at gas repackaging facilities, including fire protection systems to cool cylinders and limit the spreading of fires, adding barriers to contain exploding propylene cylinders within the facility, and gas detection systems that can sound alarms and activate fire mitigation systems.
The following video shows the initial fire spreading quickly to other cylinders. Exploding cylinders – mostly acetylene – flew up to 800 feet away, damaged property, and started fires in the community. The fire could not be extinguished until most of the flammable gas cylinders were expended. An estimated 8,000 cylinders were destroyed in the fire, which took five hours to control.
We can all learn from other people’s mistakes.
We can all learn from other people’s mistakes. The following paragraphs are taken from a press release on its investigation of a major chemical accident by the U.S. Chemical Safety Board:
The Point Comfort complex, on the Texas Gulf Coast, is the largest Formosa facility in the U.S., employing 1,400 full-time workers and 400 contactors. The accident occurred in the plant’s Olefins II Unit, which converts either natural gas liquids or naphtha into products such as propylene and ethylene. The accident began when a vehicle – a forklift towing a trailer loaded with cylinders of breathing air used in maintenance – snagged a valve, pulling it out of the system. This caused the release of a large volume of propylene which then ignited, creating a large fire. The initial explosion knocked several operators to the ground and burned two men, one seriously. Fourteen workers sustained minor injuries evacuating the complex.
The CSB Case Study concludes that had the Olefins II unit been equipped with automated shutdown valves it may have been possible to stop the propylene flow, limiting the size of the fire. Operators were unable to reach manual valves to stop the release due to the presence of the growing vapor cloud.
The investigation noted that the valve hit by the trailer was unguarded, and vulnerable to being hit by vehicles. The Case Study also noted that some steel supports were not fireproofed, and collapsed. This caused the failure of pipes designed to carry flammable hydrocarbons to the unit’s flare system, where they could be safely burned in the atmosphere. Without this safety system in place, pressurized flammable gases continued to feed the fire, which burned for five days. In addition, the CSB found that flame resistant clothing was not required for all employee activities within the Olefins II unit where there were large quantities of flammable liquids and gases.
CSB Board Member John Bresland said, “This began with a seemingly minor event, in which a trailer bumped into a drain valve. But the incident had disastrous consequences because the facility was not better prepared for a large chemical release. The fires and explosions at Formosa’s Point Comfort plant provide compelling reasons to analyze vulnerabilities that could lead to a major chemical accident.”
What follows is a short video from the CSB on its investigation and findings:
Here is a short video from California’s DTSC on the training requirements for hazardous waste generators: