ANACORTES, Wash. – The U.S. Chemical Safety Board has released its final report on the April 2010 explosion that killed seven workers at the Tesoro refinery in Anacortes.
The report was approved Thursday night at a meeting at Anacortes High School, the Skagit Valley Herald reported.
It blames the facility’s safety culture, industry standards and state and federal oversight for the catastrophic rupture of a heat exchanger at the refinery.
The federal agency is calling for more conservative standards for the use of carbon steel and calls on the state of Washington to adopt more rigorous safety management standards.
The explosion was caused by what is called a High Temperature Hydrogen Attack that severely cracked and weakened carbon steel tubing, leading to a rupture.
A draft report detailing investigation findings and recommendations was released by the board in January.
After receiving input from the United Steelworkers, the American Petroleum Institute, the Western States Petroleum Association, American Fuel and Petrochemical Manufacturers and others in industry operations and regulation, the board made a few substantial revisions to the report in its final form.
Nelson Curves are industry guidance documents used to predict and manage High Temperature Hydrogen Attack damage based on the heat and pressure a material is exposed to.
The final report recommended establishing a much more conservative Nelson Curve for carbon steel, prohibiting the use of the material in processes that operate in temperatures above 400 degrees Fahrenheit and 50 pounds per square inch of pressure.
The final version also changed recommendations made to the state.