The April 2010 fatal explosion and fire at the Tesoro refinery in Anacortes, WA was caused by damage to the heat exchanger, a mechanism known as “high temperature hydrogen attack” or HTHA, which severely cracked and weakened carbon steel tubing leading to a rupture, according to a CSB draft report. The draft report makes far-reaching recommendations to the EPA and the governor and state legislature of the state of Washington to more rigorously protect workers and communities from potentially catastrophic chemical releases.
Using sophisticated computer models, the investigation found the industry-wide method used to predict the risk of HTHA damage to be inaccurate, with equipment failures occurring under conditions the deemed to be safe from HTHA. It cited deficiencies in the company’s safety culture that led to a “complacent” attitude toward flammable leaks and occasional fires. Investigators also determined that during the unit startup, Tesoro did not correct the history of hazardous conditions or limit the number of people involved in the hazardous non-routine startup of the heat exchangers. But because of the reoccurring leaks and the need to manually open a series of long-winded valves that required over one hundred turns by hand to fully open, a supervisor requested five additional workers to help. All seven lost their lives as a result of the blast.