In April 2, 2010 at the Tesoro refinery in Anacortes, Washington, the accident occurred during startup of the refinery’s “naphtha hydrotreater unit” after a maintenance shut down. A nearly forty-year-old heat exchanger violently ruptured causing an explosion and fire that fatally injured seven workers.
The CSB’s investigation found an immediate cause of the tragedy to be long-term, undetected High Temperature Hydrogen Attack (HTHA) of the steel equipment, which led to the vessel rupture, and found the industry’s standard for determining vulnerability of equipment to HTHA, to be inadequate.
The complexity of the start up prodedure typically required more than just the one outside operator. Yet operating procedures were not updated to account for the role of additional personnel during the hazardous non-routine work.'
"Behind the Curve” includes the 3D animation of the events that led up to this tragic accident.