MARTINEZ -- An 84,000-pound spill of sulfuric acid that burned two workers at Tesoro's Golden Eagle refinery in February resulted from insufficient tightening between a tube and a compression joint in the facility's alkylation unit, according to a report released by the U.S. Chemical Safety Board on Friday.
The incident occurred when the operators opened a block valve to return an acid sampling system back to service; soon after, the tubing directly downstream of the valve came apart, spraying two operators with acid, according to a CSB news release.
The Feb. 12 incident was followed by another a month later in which two more workers were burned. The workers in both incidents were treated at hospitals and released.
"Four workers burned by sulfuric acid in less than a month clearly demonstrates there are significant opportunities within the refinery for improvement in safety performance," CSB Chairman Rafael Moure-Eraso said in a statement.
In an email, Tesoro spokeswoman Megan Wright said, "It is unfortunate that these incidents occurred; however, we are fortunate that there were protective measures in place that helped ensure that the injuries were minor."
The CSB is an independent federal agency charged with investigating chemical accidents but does not have the power to issue penalties. The state Division of Occupational Safety and Health, or Cal/OSHA, is conducting a comprehensive inspection at the Tesoro refinery with an emphasis on mechanical integrity and operating procedures, according to the CSB.