Human error 'large part of gas explosion problems'

Gas explosions at refineries can often be caused by human error, it has been suggested.

Contractor Kris Hanson told KUOW that personal safety is most at risk during start-up and shutdown operations.

Commenting after the Tesoro refinery blast in Anacortes, just north of Seattle, he said workers in the industry "pray" that nothing will go wrong while these procedures are being carried out.

"I feel a little bit funny on a start–up, because I'm always thinking about human error," he said. "You're always wondering ... Did everybody do their job?"

The news provider noted that start-ups occur after maintenance is performed on oil processors and Mr Hanson admitted that accidents are more frequent at these times.

Originally killing six workers on April 2nd, the Tesoro incident claimed another life on Tuesday, according to a company spokesman.

KUOW noted that the detonation was the deadliest at a US refinery in the last five years.