Claim: In the 2010 Tesoro Anacortes Refinery disaster, the pressure-containing shell of the heat exchanger burst at its weld seams; the ensuing explosion was so violent that many in Anacortes felt the shock wave across Fidalgo Bay (an island in Skagit County, Washington).
Evidence: The pressure-containing shell of the heat exchanger burst at its weld seams, expelling a large volume of very hot hydrogen and naphtha, which spontaneously ignited upon contact with the surrounding air. The ensuing explosion was so violent that many in Anacortes felt the shock wave across Fidalgo Bay. Fidalgo Island is an island in Skagit County, Washington, located about 60 mi (97 km) north of Seattle.