According to BP, the report confirms that the failure of BP personnel to follow established policies and procedures which led to the overfilling of the raffinate splitter tower in the refinery's isomerization unit was one of the critical factors that led to the March 23 explosion and "greatly increased its consequences."
The overfilling and overheating of the liquid contents of the raffinate splitter tower resulted in the overpressuring of one of its relief valves the blow down stack which spewed flammable liquid and vapor like a geyser just prior to the explosion. An estimated 50 barrels of liquid overflowed the tower and led to the formation of a hydrocarbon vapor cloud at ground level, according to the report.
The venting of heavier-than-air hydrocarbon into the atmosphere was one of the four critical factors identified in both BP reports.
'It's Not Clear Why' BP Personnel Failed to Sound a Warning
The failure of personnel to remove liquid from the tower the liquid level was at least 20 times higher than it should have been, according to BP or initiate any emergency action "were indicative of the failure to follow many established policies and procedures," the report says.
"Supervisors assigned to the unit were not present to ensure conformance with established procedures, which had become custom and practice on what was viewed as a routine operation," according to the report.
Another critical factor that exacerbated the severity of the incident, according to BP, was the presence of workers in and around mobile trailers within 150 feet of the blow down unit.
Both BP and the U.S. Chemical Safety and Hazard Investigation Board (CSB) have acknowledged that situating trailers so close to the blow down stack greatly increased the number of deaths and injuries, and CSB on Oct. 25 issued an urgent safety recommendation to the American Petroleum Institute to develop a new industry guideline for the positioning of trailers.
Still, BP's final report asserts that refinery personnel who were aware of the trouble brewing in the raffinate splitter could have prevented many injuries if they had warned nearby workers to leave the area.
"It is not clear why those aware of the process upset failed to sound a warning," the report says.
Use of Antiquated Equipment a Critical Factor
The fourth critical factor involved in the accident, according to BP, was the continued use of a blow down unit "for light-end hydrocarbon service" when "inherently safer options" were available.
CSB lead investigator Don Holmstrom on Nov. 10 said BP's use of obsolete equipment including a blown down unit that Holmstrom said was "half-century-old technology" is an issue BP needs to analyze at all of its U.S. refineries. (For more, read "CSB Lead Investigator to Panel: All is Not Well at BP.")
Neither BP nor CSB has conclusively determined what ignited the hydrocarbon vapors that were released into the atmosphere on March 23, although BP in its final report speculates it likely was a running vehicle engine.
Report Points to Systemic, Long-Term Safety Problems at Refinery
While the final report reiterates BP's conclusion that personnel failures played a major role in the March 23 tragedy, the investigation team says it "found no evidence of anyone consciously or intentionally taking actions or decisions that put others at risk."
However, "the team found many areas where procedures, policies and expected behaviors were not met."
"The underlying reasons for the behaviors and actions displayed during the incident are complex, and the team has spent much time trying to understand them," the report says. "It is evident that they had been many years in the making and will require concerted and committed actions to address."
The underlying causes of the March 23 accident, according to the BP investigation team, point to a number of long-term breakdowns in morale, communication, management oversight and the safety culture.
According to the BP investigation team:
- Over the years, the working environment at Texas City "had eroded to one characterized by resistance to change and lacking of trust, motivation and a sense of purpose."
- Process safety, operations performance and systematic risk-reduction priorities had not been established or consistently reinforced by management.
- Many changes in a complex organization led to a lack of clear accountabilities and poor communication, which together resulted in confusion among workers as to their roles and responsibilities.
- A poor level of hazard awareness and understanding of process safety on the site resulted in people accepting levels of risk that are considerably higher than similar operations for example, not questioning "the established industry practice" of placing mobile trailers within 150 feet of a blow down stack.
- Given the poor vertical communication and performance management process, there was neither an adequate early warning system of problems nor any independent means of understanding the deteriorating standards in the plant.
"The report clearly describes the underlying causes and management system failures that contributed to the worst tragedy in BP's recent history," BP Products North America President Ross Pillari said. "We accept the findings, and we are working to make Texas City a complex that attains the highest levels of safety, reliability and environmental performance."
CSB: 'BP's Report is a Sober Look in the Mirror'
CSB, which in October released a preliminary report from its investigation of the March 23 accident, will review BP's final report over the next several weeks, CSB Chairman Carolyn Merritt said today.
"I commend BP for making its final report public, for cooperating with CSB's independent investigation and for pledging corrective actions in the aftermath of this tragedy," Merritt said. "BP's report is a sober look in the mirror that reveals an ineffective safety culture at the Texas City refinery. I urge the company to draw upon this report and enact any needed changes not just in Texas City but at all facilities worldwide. The CSB plans to request an update from BP on its implementation of the report's recommendations over the next few months."