Texas City Refinery (BP)

BP's Texas City Refinery in Texas City, Texas is the second-largest oil refinery in the state and the third-largest in the United States. It has an input capacity of 437,000 barrels per day (18,354,000 gallons or 69,477,448 litres) as of January 1, 2005. A major explosion occurred in an isomerization unit at the site on March 23, 2005, killing 15 workers and injuring more than 500 others.

Explosion

ummary

On Wednesday March 23, 2005, the startup of the isomerization (ISOM) unit (after a temporary downtime) led to an explosion, which killed 15 and harmed over 170 people at the Texas City refinery. It has been noted as one of the most serious industrial incidents in the past two decades. According to the report:

'Actions taken or not taken led to overfilling the raffinate splitter with liquid, overheating of the liquid and the subsequent overpressurisation and pressure relief. Hydrocarbon flow to the blowdown drum and stack overwhelmed it, resulting in liquids carrying over out of the top of the stack, flowing down the stack, accumulating on the ground, causing a vapor cloud, which was ignited by an abandoned white pickup truck with the ignition on.

The report identified numerous failings in equipment, risk management, staff management, working culture at the site, maintenance and inspection and general health and safety assessments.

Detail

The U.S. Chemical Safety and Hazard Investigation Board investigating the incident found that operators had started-up the raffinate splitter tower (which separates light and heavy gasoline components) of the ISOM unit (which increases the octane rating of gasoline) and begun filling it with hydrocarbon fluid (i.e. gasoline components) without beginning timely discharge of product.

The operators started the tower while ignoring open maintenance orders on the tower’s instrumentation system. The design of the level indicator meant that it only read a length of 3 metres; anything above that did not register. In addition, the design was such that any level above 3 metres could show on the screen as a drop in level. There was a secondary alarm which should have gone off if liquid exceeded 2.5m. However, no one heard it, since the alarm was reported as damaged before the accident and there were no records of it being fixed. Out of the two alarms, one was deactivated and the back-up never worked in the first place. The supervisor was not present for the critical start-up phase, as he went to see a family member who had an accident after receiving a phone call about it. Training had been perfunctory and did not include adequate simulation of off-nominal situations. Because of these issues, the operators lost situational awareness of conditions inside the tower and ignored available indications of impending mishap.

Once the lack of draw-down from the tower was recognised, operators opened the discharge valve. This worsened the problem because the hot discharges passed through a heat-exchanger that pre-warmed incoming fluids. The resulting increase in temperature caused the formation of a bubble of vapor at the bottom of the raffinate tower that was already overly full and overheated. The tower burped the vapor bubble and the liquid above the bubble into the overhead relief tube of the tower.

The relief tube was connected to a disposal system for relieved discharges. The particular type of disposal system serving the raffinate tower was a blow-down drum with an atmospheric vent stack rather than an inherently safer and more environmentally sound knock-out tank and flare system.

Because of the overfilling of the raffinate splitter tower and the burp of both vapors and liquids to the undersized blow-down drum with an atmospheric vent stack, a “geyser like” emission of hot flammable vapors and liquids was expelled from the vent stack. The next focus was on the trailer where most of the victims died. It was only 35m from the blow-down stack and it was not the first time workers died this way. In 1995, a refinery belonging to Pensoil suffered a disaster when two storage tanks exploded, engulfing a trailer and killing 5 workers. The conclusion was that trailers should not be located near hazardous materials. However, BP ignored the warnings, and they believed that because the trailer was empty most of the year, the risk was low. According to "Seconds From Disaster", there was a white diesel pick-up truck parked not far away from the blow down stack. The driver got out and left the engine running. When the liquid escaped from the blow down stack, it flowed under the pick-up truck and the vapor entered the engine's air intake, causing the engine to rev. A plant worker heard the seemingly mysterious revving of the truck's engine prior to the accident. A short while after, a spark in the engine set off the explosion that killed 15 and injured 170. The CSB recommended that the American Petroleum Institute (API) establish guidelines for locating occupied trailers away from hazardous areas.

Between 1994 and 2004 at least 8 similar cases occurred in which flammable vapors were emitted by the same blow-down drum vent stack. Effective corrective action was not taken.

The CSB found that BP continued to use blow-down drums with atmospheric vent stacks for disposal of flammables emitted by the ISOM unit pressure relief system instead of inherently safer and more environmentally sound alternatives such as properly sized knock-out tanks with a flare. Prior to the 2005 accident, BP operated 17 blow-down drums for disposal of flammable materials at its five U.S. refineries.

The CSB found BP safety standards adopted from AMOCO (the previous owner of the refinery) and in force since 1977 prohibited new blow-down drum / vent stack systems and called for replacement of existing blow-down drum / vent stack systems with inherently safer alternatives when modifications of the plant created an opportunity. In 1997 BP replaced the 1950’s era blow-down drum / vent stack that served the raffinate splitter tower with an identical system instead of upgrading to the inherently safer alternative. As of 20-Jan-2007 the reason for this decision has not yet been published.

In 1992 OSHA had cited a similar blow-down drum & vent system at the plant (then owned by AMOCO) for violations of the ASME Boiler and Pressure Vessel Code. OSHA abandoned the citation when AMOCO argued that their current practices conformed to API Recommended Practice 521 "Guide for Pressure-Relieving and Depressurizing Systems". During the accident investigation the CSB recommended that API RP521 be modified to better meet the intent of the ASME Boiler and Pressure Vessel Code regarding safe disposal of flammable liquids & vapors emitted by relief valve safety systems. They also recommended that OSHA undertake a “national emphasis” program to eliminate blow-down drum / vent stack systems in flammable service. As of 20-Jan-2007 these recommendations have not yet been acted upon.

In 2002 Engineers at the plant proposed replacing the blow-down drum / vent system as part of an environmental improvement initiative but this line item was cut from the budget due to cost pressures.

As a result of the accident BP has stated that it will eliminate all blow-down drums / vent stack systems in flammable service. This author does not know the status of progress on this commitment as of 20-Jan-2007.

On Monday, 4-Feb-2008, U.S. District Judge Lee Rosenthal heard arguments regarding BP's offer to plead guilty to a federal environmental crime with a US$50 million fine. At the hearing, blast victims and their relatives objected to the plea, calling the proposed fine "trivial." So far, BP has said it has paid more than US$1.6 billion to compensate victims. [cite news |first=Lisa |last=Baldwin |title=BP Explosion Victims' Relatives Oppose Plea |url=http://www.click2houston.com/news/15210120/detail.html |publisher=Click2Houston.com |date=2008-02-04 |accessdate=2008-02-04 ] The judge gave no timetable on when she would make a final ruling.cite news |first=Juan A. |last=Lozano |title=Judge mulls BP plea in Texas plant blast |url=http://www.businessweek.com/ap/financialnews/D8UJSQ880.htm |publisher=Associated Press |date=2008-02-04 |accessdate=2008-02-05 ]

ubsequent Incidents

After the ISOM unit explosion three other major safety incidents occurred at the plant.

Unit ruptured causing a release of hydrogen that erupted into a large fireball. One person received minor injuries. There were no fatalities from this incident. The Chemical Safety Board found that had accidentally switched a carbon steel pipe elbow with a low alloy steel elbow during maintenance. The carbon steel elbow was therefore, improperly used in an application that involved exposure to hydrogen gas at temperatures above 500F and pressures above 100psia (possibly as high as 3000psig). In that environment carbon steel is susceptible to a failure mode known as “High Temperature Hydrogen Attack” (HTHA). In such an environment low alloy steel is normally used to avoid HTHA. The physical dimensions and bolting patterns of the two types of elbows were identical (i.e. interchangeable) even though the material requirements were different. The CSB found that BP had not informed the maintenance contractor that the elbows were different, the maintenance contractor had not used any procedure (such as tagging) to ensure that the elbows were re-installed into their original locations. The CSB also noted that the Positive Material Verification (PMI) program at the plant only required PMI testing (using x-ray fluorescence or other non-destructive testing techniques) of materials when initially purchased and when being dispensed for use in new construction but PMI testing was not required for materials dispensed for re-installation following maintenance. The CSB recommended that maintenance contractors track components to ensure proper re-installation and that the PMI program be expanded to include testing of maintenance items dispensed for re-installation.

On 10-Aug-2005 there was an incident in a Gas-Oil Hydrotreater that resulted in a community order to shelter. This incident occurred when a hole developed in the bottom of a vale that handles high pressure gas and oil.

On 14-Jan-2008, William Joseph Gracia, 56, a veteran BP operations supervisor, died following head injuries sustained as workers prepared to place in service a water filtration vessel at the refinery's ultracracker unit. [cite news |first=Mary |last=Flood |title=Agency to investigate death at BP refinery |url=http://www.harriscountytx.net/cache/5465436.pdf |publisher=Houston Chronicle |date=2008-01-17 |accessdate=2008-01-18 ]

Baker Panel

On 17-Aug-2005 the CSB recommended that BP Headquarters commission an independent panel to investigate the safety culture and management systems at BP North America. The panel was led by former US Secretary of State James Baker III. The Baker panel report was released on 16-Jan-2007. The principal finding was that BP management had not distinguished between “occupational safety” (i.e. slips-trips-and-falls, driving safety, etc.) vs “process safety” (i.e. design for safety, hazard analysis, material verification, equipment maintenance, process upset reporting, etc.). The metrics, incentives, and management systems at BP focused on measuring and managing occupational safety while ignoring process safety. BP confused improving trends in occupational safety statistics for a general improvement in all types of safety.

Additionally the panel created and administered to all five of BP’s North American refineries an employee survey focusing on various aspects of “process safety”. From the survey results they concluded that the Toledo and Texas City plants had the worst process safety culture while the Cherry Point refinery had the best process safety culture. The survey results also showed that managers and white collar workers generally had a rosier view of the process safety culture at their plants when compared with the viewpoint of blue collar operators and maintenance technicians. The director of the Cherry Point refinery was promoted to oversee better implementation of process safety at BP. While the head of BP (Lord John Browne) retired early amid the various problems plaguing BP in 2005 and 2006 (including the problems at Texas City, the shutdown of the Alaska pipeline, allegations of propane market manipulation, and start-up delays of the Thunderhorse project in the Gulf-of-Mexico).

ee also

*National Geographic "Seconds From Disaster" episodes

External links

* [http://www.csb.gov/ US Chemical Safety Board]
* [http://www.bpresponse.org/ BP: Texas City Refinery Incident - March 23, 2005]
* [http://www.bp.com/liveassets/bp_internet/us/bp_us_english/STAGING/local_assets/downloads/t/final_report.pdf BP Accident Investigation Report]
* [http://www.bp.com/bakerpanelreport Baker Panel Report]
* [http://www.csb.gov/index.cfm?folder=current_investigations&page=info&INV_ID=52 Chemical Safety Board Investigation Status Page]
* [http://www.chron.com/content/chronicle/special/05/blast/index.html Special Report: 2005 Texas City Explosion.] "Houston Chronicle".
* [http://www.untcip.net/alfredo/Daniel/GEIP/11/Explosion.pdf BP Refinery Explosion] Pictures and captions (PowerPoint Presentation in Spanish)

References