Loose pipe fittings are to blame for a sulfuric acid release that seriously injured two workers in early February at the alkylation unit of Tesoro Corp.’s 161,000-b/d Golden Eagle refinery near Martinez, Calif., according to an Aug. 15 report released by the US Chemical Safety Board (CSB) (OGJ Online, Feb. 24, 2014).
Prepared by California-based engineering and laboratory testing firm Anamet Inc., the report details findings from a technical examination of stainless-steel tube assembly recovered by the California Division of Occupational Safety and Health (Cal/OSHA) following the Feb. 12 incident.
According to the report, the spill of 84,000 lb of sulfuric acid immediately resulted from the insufficient tightening upon installation of a tube and a compression joint located at a sulfuric acid sampling station in the refinery’s alkylation unit.
The insufficient tightening between the tube, which was being pressurized at the time of the incident, and the compression joint allowed the tube to be forced from the joint, most likely by internal pressure, the report says.
“This incident highlights the need for strong process safety management at facilities that ensures mechanical integrity is verified prior to the introduction of hazardous chemicals into equipment,” CSB Chairperson Rafael Moure-Eraso said in a statement.
The need becomes all the more necessary, says Moure-Eraso, given another incident on Mar. 10 in the same sulfuric acid alkylation unit at the Golden Eagle refinery, when two additional contract workers were sprayed with sulfuric acid while conducting planned maintenance.
“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,” Moure-Eraso said.
Cal/OSHA—who ordered the Golden Eagle alkylation unit shut from Feb. 18-28 based upon testimony from refinery workers that they were afraid to operate the unit prior to the Feb. 12 incident amid safety concerns—is continuing a separate regulatory investigation at the refinery.
Cal/OSHA’s investigation at Golden Eagle is focusing on the refinery’s mechanical integrity and operating procedures, according to CSB.