pdf file too large to upload but here is the web link for those interested...

http://www.tsocorp.com/stellent/groups/corpcomm/documents/gt_contribution/001347.pdf

I have worked this facility years ago and living in Oregon it hits close to home.  The report is very informative and provides the origin of failure as being HTHA high temperature hydrogen attack in the Naphtha Hydrotreater unit at the Tesoro Anacortes Refinery.

"On April 2, 2010, at approximately 12:35 a.m., a heat exchanger, E-6600E, in the
Naphtha Hydrotreater unit at the Tesoro Anacortes Refinery ruptured, releasing a mix of
hydrogen and naphtha. The dispersed material auto-ignited, causing an explosion and
fire which fatally injured seven employees who were in the area while a parallel bank of
E-6600s were being placed in service." (excerpt from report)