Wikipedia Commons, Walter Siegmund

The U.S. Chemical Safety Board has released its draft report on the investigation of the explosion at the Tesoro refinery in Anacortes, Wash., in April 2010, identifying a "high temperature hydrogen attack," or HTHA, as the cause of the incident.

HTHA causes damage to the heat exchanger, which results in cracks and weakens the carbon steel tubing. The report claimed that the company failed to identify the problem and this led to the rupture of the tubing, causing a fatal explosion and fire at the refinery. The board stated that the company had a "complacent" attitude towards occasional fires that had occurred prior to the explosion.

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The Chemical Safety Board not only found fault with Tesoro and its lack of action to prevent the incident. The report also made a series of recommendations to regulators, noting that the there are no requirements for refiners to address HTHA. It urged the U.S. Environmental Protection Agency and the Governor and State Legislature of the State of Washington to do more to protect communities and employees from chemical incidents.

One of the recommendations made by the board calls for the introduction of a safety oversight system similar to that implemented in the United Kingdom. British regulators require refineries to have the most up-to-date technology and implement rigid safety practices.

The board will vote on a final version of the report later this year.