Oct 27, 2005
CSB Issues Preliminary Findings in BP Texas City Refinery Accident; Investigators Present Data in Public Meeting
Texas City, Texas, October 27, 2005 - In preliminary findings set to be released at a public meeting here tonight, investigators from the U.S. Chemical Safety and Hazard Investigation Board have identified six key safety issues underlying the March 23 explosions and fire at BP's Texas City refinery, an incident which killed 15 workers and injured 170 others. The six identified safety issues were:
(1) Trailers were placed in an unsafe location, too close to an isomerization (isom) process unit handling highly hazardous materials. All the fatalities occurred in and around trailers that were as close as 121 feet from the release. One trailer located 600 feet from the explosions was heavily damaged, and 39 other trailers were either damaged or destroyed.
(2) The unit's raffinate splitter should not have been started up due to existing malfunctions of the level indicator, level alarm, and a control valve.
(3) The raffinate splitter tower had a history of abnormal startups that included recurrent high liquid levels and pressures.
(4) The day of the incident, a blowdown drum vented highly flammable material directly to the atmosphere. The drum was never connected to a flare since its construction in the 1950s. The previous owner of the refinery, Amoco Corporation, replaced the isom unit blowdown drum in 1997 with identical equipment; Amoco refinery safety standards recommended connecting the drum to a flare when such major modifications were undertaken but this was not done.
(5) Between 1995 and March 23, 2005, there were four other serious releases of flammable material from the isom blowdown drum and stack that led to ground-level vapor clouds; fortunately none ignited.
(6) In 1992 OSHA cited a similar blowdown drum and stack at the Texas City refinery as unsafe because it vented flammable material directly to the atmosphere, but the citation was dropped and the drum was not connected to a flare system.
The public meeting is scheduled for 6 p.m., Thursday, October 27, at the Doyle Center, 2010 Fifth Avenue North in Texas City. Following the investigators' presentation, the Board will call for comments by members of the public.
CSB Chairman Carolyn W. Merritt said, "The meeting tonight marks an important milestone in the Board's independent investigation of the tragedy at BP Texas City. The preliminary findings we present this evening should be reviewed throughout the industry, which shares the CSB's goal of safer operations in the future. I also commend BP for cooperating with our investigation. BP has provided witnesses and documents on a voluntary basis and has facilitated testing of critical equipment."
CSB investigators released three detailed computer animations of the startup of the isom unit, the vapor cloud formation, and the subsequent explosions. The simulations showed a vapor cloud that blanketed much of the nearly five-acre isom unit just before the cloud was ignited, most likely by an idling diesel pickup truck.
The process simulation depicts liquid hydrocarbon flows through a complex of piping connecting a heat exchanger, a furnace, the raffinate splitter tower, and the blowdown drum. As the temperature and fluid levels increase inside the tower, the animation shows pressure-relief valves directing overflow to the blowdown drum and attached vent stack. The drum rapidly fills, finally causing a geyser-like release of flammable liquids from the top of the vent stack. The vaporizing liquid falls to the ground, where it forms a vapor cloud.
CSB Lead Investigator Don Holmstrom said, "The first rule of oil refinery safety is to keep the flammable, hazardous materials inside piping and equipment. A properly designed and sized knockout drum and flare system would have safely contained the liquids and burned off the flammable vapors, preventing a release to the atmosphere." Mr. Holmstrom said investigators found evidence that BP evaluated connecting the raffinate splitter to a flare system in 2002 but ultimately decided against it. After the March 2005 incident, BP said it would eliminate blowdown stacks that vent directly to the atmosphere at all U.S. refineries.
Investigators presented new details on the 16 previous startups of the raffinate splitter from 2000 onward. They found eight startups with tower pressures of at least double the normal value, and thirteen startups with excess liquid levels. These abnormal startups were not investigated by BP. "Investigations of these incidents could have resulted in improvements in tower design, instrumentation, procedures, and controls," Mr. Holmstrom stated.
In his presentation, Mr. Holmstrom said that there was no supervisor with appropriate experience overseeing the startup at a critical time on March 23. Operators did not follow the requirements of startup procedures, including opening the level control valve for the splitter tower. This omission allowed the tower level to rise rapidly for three hours, to fifteen times its normal level. Operators were misled by the malfunctioning level indicator on the tower and a separate high-level alarm which failed to activate. The training and experience of the operators remains under investigation.
Investigators stated that a variety of equipment problems made it unsafe to start up the raffinate splitter on March 23. "Proper working order of key process instrumentation was not checked as required by the startup procedure. Managers turned away technicians and signed off on the instrument tests as if they had been done," Mr. Holmstrom said. Investigators also found that BP's traffic policy allowed vehicles unrestricted access near process units. On the day of the incident, there were running vehicles including a diesel pickup truck as close as 25 feet from the blowdown drum. A total of 55 vehicles were located in the vicinity of the drum, investigators determined, and one likely served as the ignition source for the explosions.
Based on findings from its BP investigation, the CSB earlier this week issued two new urgent recommendations to leading U.S. petrochemical trade organizations. The Board called on the American Petroleum Institute (API) to develop new safety guidance that establishes minimum distances for occupied trailers away from hazardous areas of process plants. The Board also called on API and the National Petrochemical & Refiners Association (NPRA) to immediately contact their members urging "prompt action to ensure the safe placement of occupied trailers away from hazardous areas of process plants," before the new API safety guidance is completed.
A final public report of the investigation is expected in 2006. Chairman Merritt said, "The investigation will continue with further equipment testing, witness interviews, and the analysis of root causes. Most importantly, we will be developing additional safety recommendations to prevent similar incidents at companies around the country. Investigation alone cannot bring back what has been lost, but we can learn from this tragedy and prevent the loss of life in the future."
The CSB is an independent federal agency charged with investigating industrial chemical accidents. The agency's board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in safety management systems, regulations, and industry standards.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. Visit our website, www.csb.gov.
For more information, in Houston contact Daniel Horowitz (202) 441-6074; Sandy Gilmour (202) 251-5496; Kara Wenzel (202) 577-8448; or Lindsey Heyl (202) 725-2204.