Tesoro Accident Report Finalized

A controversial proposal that recommended an overhaul in how U.S. refineries are regulated has been stripped from a final Chemical Safety & Hazard Investigation Board (CSB) report that was released at a public meeting on May 1 in Anacortes, Wash.

The final report presented the results of CSB’s investigation of the Tesoro refinery accident that killed seven workers four years ago. Because of the severity of the Tesoro accident and the frequency of other U.S. refinery accidents, the board had proposed in a draft report a new “safety case” regulatory approach for refineries. The technique is used in the U.K. and other countries and requires companies to work with regulators to develop regulatory requirements. Once developed, the performance-based regulatory system is overseen by government officials, according to CSB.

Although CSB staff, backed by Chairman Rafael Moure-Eraso, worked on the safety case proposal for a year, it was opposed by the two other members of the three-person board as well as by the United Steelworkers union and refineries (C&EN, Feb. 17, page 25). CSB first presented the approach as part of a draft report for another refinery accident—this one at a Chevron facility in Richmond, Calif., in 2012—at a January meeting. At that time, CSB members Beth Rosenberg and Mark Griffon voted down that draft because of the safety case recommendation. A final Chevron accident report has yet to be released.

At the Tesoro meeting earlier this month, the final report was made public. The safety case provisions had been removed. The change was supported by Rosenberg and Griffon, and the long-delayed report was finalized and released with unanimous board approval.

Most other draft report provisions and recommendations remain in the final report. Also remaining is the finding of the cause of the accident, which the board says was the largest U.S. refinery accident since the 2005 BP Texas City, Texas, explosion that killed 15 workers and injured 180.

The immediate cause of the Tesoro tragedy, the report says, was long-term, undetected “high-temperature hydrogen attack” (HTHA) of carbon steel equipment in a heat exchanger. The conditions on the day of the accident led to corrosion and vessel rupture and a massive, deadly release of a highly flammable combination of hydrogen and naphtha, a mix of liquid hydrocarbons.

“We found the industry’s standard for determining vulnerability of equipment to HTHA to be inadequate,” Moure-Eraso says. “We also found Tesoro’s safety culture to be lacking, which led to a complacent attitude toward flammable leaks and occasional fires over the years.” In the report, he notes, CSB makes strong recommendations in these areas both to the American Petroleum Institute (API), an oil industry trade association, and to Tesoro.

In its investigation, CSB found that Tesoro, like other refineries, uses API-prepared “Nelson curves” to predict susceptibility of carbon steel piping and equipment to HTHA damage. CSB found the curve data to be unreliable because they are based on historic data that do not reflect actual operating conditions.

API is now reexamining its requirements for carbon steel used in high-temperature conditions, says the association’s spokesman, Carlton Carroll. In 2011, it acknowledged the problem and sent an alert to its refinery members warning that welds that are not heat treated are more susceptible to HTHA than previously thought. “We are collecting data to make improvements in the next edition of the standard,” Carroll adds.

Because of the Tesoro and other refinery accidents, CSB says it is recommending “sweeping changes” to the regulatory system, aside from the safety case approach.

For example, the Tesoro report stresses the importance of inherently safer design, an analytical tool used to compare options within a given manufacturing process. The goal is to encourage substitution for or minimization of hazardous chemicals as well as to simplify complex industrial processes that use hazardous chemicals.

“We are calling on the Environmental Protection Agency to revise rules in its Chemical Accident Prevention Provisions to require the use of inherently safer systems analysis,” Moure-Eraso says. “CSB is also encouraging use of what is called the ‘hierarchy of controls’ to the greatest extent feasible when facilities are establishing safeguards for identified process hazards.” The hierarchy of controls is a risk-based ranking of options to limit hazards.

The report also calls for the state of Washington to conduct comprehensive process hazard analyses and to use inherently safer systems analysis. The board urges the state to hire more process safety management inspectors, noting that currently the state has just four such specialists to regulate and inspect some 270 facilities, including five refineries.

The United Steelworkers union, which represents most Tesoro workers, has concerns about CSB’s recommendations. Particularly, according to Kim Nibarger, a union health and safety specialist, the report downplays the importance of frequent inspections.

Pointing to the rupture, Nibarger says normally HTHA damage is microscopic, but the crack that led to the accident was 4 feet long and quite advanced. “It could have been found through more rigorous inspection,” he says.

“Our people are literally living and dying from equipment that is not being inspected and maintained adequately and is failing,” Nibarger says.

“We are certainly not opposed to inherently safer approaches, and it is a mistake not to do this,” he adds. “But U.S. refineries are 50, 60 years old, and the time to do inherently safer analyses is during design and construction.” After plants are built, regulators should rely more on inspections, he says.

On the other hand, Nibarger is pleased that CSB backed off its call for a safety case approach. United Steelworkers, Nibarger says, has discussed the safety case with Unite, a large U.K. union similar to the United Steelworkers.

“Some things in the safety case could work well in the U.S. and could be used to strengthen our process safety management regulations,” Nibarger says. But there are significant differences, which he believes could hurt U.S. workers. For example, the U.K. has many more inspectors for some seven refineries in the country, he explains.

“Once a year, an inspector will visit a U.K. refinery,” he says. “In the U.S., refineries are inspected only when something happens in the plant or someone files a complaint. For the safety case to work in the U.S., we would need to hire a whole lot more competent safety inspectors, and I don’t think that is likely to happen.”

When asked by C&EN about its response to the report, Tesoro issued a statement disagreeing with many findings.

“Most importantly, we take exception to CSB’s inaccurate depiction of our process safety culture,” a Tesoro spokeswoman says, adding that it has already taken some actions to improve safety.

CSB and Tesoro have had a difficult relationship. Last February, two employees at Tesoro’s Martinez, Calif., refinery suffered first- and second-degree acid burns and were briefly hospitalized. When CSB staff attempted to investigate the accident, they were blocked from entering the facility. CSB complained, but the disagreement was not resolved.

In the months ahead, CSB says, it will continue to examine application of a more rigorous regulatory regime for refineries, including application of the safety case, as the board finalizes its Chevron accident report.