March 9, 2023

CSB Highlights Hazards of Emergency Discharges from Pressure Release Valves

In a safety alert released on Monday, the Chemical Safety and Hazard Investigation Board (CSB) urged companies to adopt safer practices for emergency discharges from pressure release valves. Pressure-relief systems are designed to protect equipment from unexpectedly high pressures by transferring hazardous materials to a safe location. But CSB’s safety alert highlights four incidents in which the venting of flammable, toxic, or hazardous materials resulted in 19 fatalities and more than 200 injuries.

In one incident, horizontal piping at a chemical plant in Pasadena, Texas, discharged flammable ethylene vapor near workers. Some were forced to jump from the second or third stories of the plant, while others were injured during the evacuation. In another incident, methyl mercaptan was released from a chemical manufacturing facility in LaPorte, Texas, causing the deaths of four workers. A third incident, in West Carrollton, Ohio, stemmed from the release of highly flammable vapor from a waste recycling process and led to a series of explosions. The fourth incident occurred at the BP refinery in Texas City, Texas, when a release of flammable hydrocarbons led to an explosion that killed 15 workers and seriously injured 180 people.

CSB’s safety alert recommends that facilities follow guidance from American Petroleum Institute Recommended Practice 521, Pressure-Relieving and Depressuring Systems, and API RP 14C, Analysis, Design, Installation, and Testing of Safety Systems for Offshore Production Facilities, and points to resources from the American Institute of Chemical Engineers. Facilities should also determine safe discharge locations for hazardous chemicals.

For more information, read the CSB press release and download the safety alert (PDF).