Four workers were severely burned at the ExxonMobil refinery in Baton Rouge, Louisiana last year because the facility operators failed to conduct a safety hazard analysis, according to the U.S. Chemical Safety Board (CSB), which investigated the incident.
How it happened
The fire occurred during maintenance activities when operators inadvertently removed bolts that secured a piece of pressure-containing equipment to a plug valve. When the operators attempted to open the plug valve, the valve came apart and released flammable hydrocarbons, which formed a vapor cloud that quickly ignited.
Chairperson Vanessa Allen Sutherland said, “Our investigation found that these accepted practices were conducted without appropriate safety hazard analysis, needlessly injuring these workers. It is important to remember that good safety practices are good maintenance practices and good business practices.”
A key safety lesson discussed in the bulletin is the “hierarchy of controls.” This is a method of evaluating safeguards to provide effective risk reduction. Within the hierarchy of controls, an engineering control, such as improved valve design, is more effective than a lower level administrative control, such as a sign warning workers that the gearbox support bracket connects to pressure-containing components.
The CSB reports concludes that updating all of the older valves to the safer valve design, as was done to approximately 97% of the valves in the unit, would have ultimately prevented the incident
Investigator Mark Wingard said, “Our investigation also revealed a culture at the refinery that was accepting of operators performing maintenance on malfunctioning plug valve gearboxes without written procedures or adequate training, which in this instance, resulted in a hazardous event.”
The CSB is issuing Key Lessons to address the shortcomings revealed by the investigation:
1. Evaluate human factors - humans associated with operational difficulties that exist at a facility in relation to machinery and other equipment, especially when the equipment is part of a process covered by the Occupational Safety and Health Administration’s Process Safety Management (PSM) standard. Apply the hierarchy of controls to mitigate the identified hazards.
2. Establish detailed and accurate procedures for workers performing potentially hazardous work, including job tasks such as removing an inoperable gearbox.
3. Provide training to ensure workers can perform all anticipated job tasks safely. This training should include a focus on processes and equipment to improve hazard awareness and help prevent chemical incidents.
The CSB is an independent, non-regulatory federal agency charged with investigating industrial chemical accidents. The agency's board members are nominated by the president and confirmed by the Senate. CSB investigations examine all aspects of chemical accidents, including physical causes such as equipment failure or inadequacies in regulations, industry standards, and safety management systems.
The Board does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. www.csb.gov.