(205d) U.S. Chemical Safety Board's Final Investigation Report on the Chevron Richmond Refinery Pipe Rupture and Fire

On August 6, 2012, the Chevron U.S.A. Inc. Refinery in Richmond, California (Chevron Richmond Refinery) experienced a catastrophic pipe rupture in the #4 Crude Unit.  The incident occurred from piping referred to as the “4-sidecut” stream, one of several process streams exiting the refinery’s C-1100 Crude Unit Atmospheric Column.  The pipe rupture occurred on a 52-inch long component of the 8-inch 4-sidecut line.  The rupture of the 4-sidecut piping was the result of the 52-inch component being extremely thin due to unidentified, accelerated sulfidation corrosion in the low-silicon piping component. 

The ruptured pipe released a flammable, 640°F light gas oil, which then partially vaporized into a large, opaque vapor cloud that engulfed 19 Chevron employees.  Approximately two minutes after the release, the flammable portion of the vapor cloud ignited. Eighteen of the employees safely escaped from the cloud just before ignition; one employee, a Chevron refinery firefighter, was inside a fire engine that was caught within the fireball when the vapor cloud ignited.  Because he was wearing full body fire-fighting protective equipment, he was able to make his way through the flames to safety.  Six Chevron employees suffered minor injuries during the incident and subsequent emergency response efforts.  The leak resulted in a large plume of vapor which traveled across the Richmond, California, area. The ignition and subsequent burning of the hydrocarbon process fluid created a large cloud of  particulates which also swept across the Richmond area.  In the weeks following the incident, approximately 15,000 people from the surrounding communities sought medical treatment at nearby medical facilities for ailments including breathing problems, chest pain, shortness of breath, sore throat, and headaches.  Approximately 20 of these people were admitted to local hospitals as inpatients for treatment.