The U.S. Chemical Safety Board has released its draft report into the causes of a devastating 2010 explosion at a Tesoro refinery on Puget Sound. The accident killed seven workers, and the community has been increasingly upset by how long the investigation has dragged on.

Now the draft report is out, and it's accompanied by a fascinating computer animation that's quite instructive — especially to the uninitiated.

Watching the video below, you get a much better appreciation for how a witch's brew of chemicals can eat away at steel tanks, and the very real dangers faced every day by the people who refine the petroleum products that we take for granted.

The CSB is an independent investigative agency, and its recommendations aren't necessarily binding. But, given the death toll, there may be more pressure on the refinery industry to emulate the European system of aggressively identifying potential hazards, such as hydrogen-weakened steel, in order to minimize them.

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