Summary
The 2010 Tesoro Anacortes Refinery disaster occurred on April 2, 2010. Seven workers received fatal burns in an explosion and ensuing fire when a heat exchanger violently ruptured after a maintenance restart.
Key Learnings / Issues
- HTHA not identified as a credible damage mechanism during reviews as design (rather than operating) conditions were used.
- HTHA is very difficult to inspect for; therefore, inspection is not sufficient to ensure mechanical integrity and an inherently safer design is needed.
- Frequent hydrocarbon leaks were normalised and not investigated.
- The supervisor requested five additional operators to assist with the startup (exposing more personnel to risk) due to the frequent leaks.
- The refinery’s process safety culture required proof of danger rather than proof of effective safety implementation.
Quote
“The NHT heat exchangers frequently leaked flammable hydrocarbons during startup, sometimes resulting in fires. Tesoro management had been complacent about these hazardous leaks and did not always investigate the cause of the leaks.”
From the CSB’s investigation report.