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Tesoro Corp did not adequately maintain a heat exchanger at its Anacortes, Washington, refinery that exploded one year ago leaving seven dead, a safety board said.

Companies need to “make the investments necessary to ensure safe operations,” said U.S. Chemical Safety Board (CSB) Chairperson Rafael Moure-Eraso. “Companies that continue to invest in safety and recognize its importance will reap benefits far into the future.”

The CSB released a video that highlights the ongoing investigation into the April 2, 2010 incident. At the time of the incident a heat exchanger was coming online when the nearly forty-year-old piece of equipment catastrophically failed, spewing highly flammable hydrogen and naphtha which ignited and exploded.

Aerial view of the damaged heat exchangers following the April 2, 2010 fire

Aerial view of the damaged heat exchangers following the April 2, 2010 fire

Cyber Security

Microscopic cracks had formed in the walls of the exchanger in a common phenomenon seen in metal where hydrogen is present under high temperature called high-temperature hydrogen attack, said Moure-Eraso in a video.

“This led to a violent rupture of the exchanger followed by an intense fire as large volumes of naphtha and hydrogen were released,” Moure-Eraso said

A Tesoro spokesman said the company does not agree with the CSB’s assessment about maintenance at the refinery.

Tesoro spokesman Mike Marcy said the heat exchanger “was maintained and inspected in accordance with regulations and industry standards.”

In October, the Washington state Department of Labor & Industries fined Tesoro $2.38 million for safety violations in the blast including a failure to maintain and test the heat exchanger at the refinery.

Tesoro is appealing the fine before the Washington state Board of Industrial Insurance Appeals.

“Our position has been that had Tesoro conducted the appropriate and required testing, they would have found the cracking that led to the rupture,” said Hector Castro, spokesman for Washington Department of Labor & Industries.

A Tesoro spokesman said the heat exchanger was inspected in 2005, three years ahead of the required 10-year inspection, and was not due for re-inspection until 2015.

The United Steelworkers union, which represents hourly workers at the refinery, said the explosion was preventable.

“The industry has known that to prevent such an incident from happening any type of equipment in contact with high temperature hydrogen has to be maintained and inspected more so than in other processes,” USW spokeswoman Lynne Baker said in a statement. “This was a preventable accident.”

“The Tesoro accident is only one of several fatal incidents that occurred in the oil and gas production and refining sector in 2010 alone. Serious incidents at refineries continue to occur with alarming frequency,” Moure-Eraso said.

The video notes insurance industry statistics indicating the U.S. refining sector has more than three times the rate of property losses of refineries overseas.

To prevent accidents, companies should:
• Implement a robust mechanical integrity programs with an emphasis on thorough inspections of critical equipment
• Monitor process safety performance using appropriate leading and lagging indicators to measure process safety before major accidents occur
• Maintain an open and trusting safety culture where near-misses and loss of containment incidents are reported and investigated

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