Texas City Refinery explosion
On the 23rd, March 2005, a hydrocarbon vapour cloud explosion occurred at the ISOM isomerization process unit at BP's Texas City refinery in Texas City, Texas, killing 15 workers and injuring more than 170 others. The Texas City Refinery was the second-largest oil refinery in the state, and the third-largest in the United States with an input capacity of 437,000 barrels (69,500 m3) per day as of January 1, 2000. BP acquired the Texas City refinery as part of its merger with Amoco in 1999. 
BP's own accident investigation report  stated that the direct cause of the accident was “…heavier–than-air hydrocarbon vapors combusting after coming into contact with an ignition source, probably a running vehicle engine. The hydrocarbons originated from liquid overflow from the F-20 blowdown stack following the operation of the raffinate splitter overpressure protection system caused by overfilling and overheating of the tower contents.” Both the BP and the Chemical Safety and Hazard Investigation Board reports  identified numerous technical and organisational failings at the refinery and within corporate BP. Organisational failings included corporate cost-cutting, a failure to invest in the plant infrastructure, a lack of corporate oversight on both safety culture and major accident prevention programs, a focus on occupational safety and not process safety, a defective management of change process [which allowed the siting of contractor trailers too close to the ISOM process unit), the inadequate training of operators, a lack of competent supervision for start-up operations, poor communications between individuals and departments and the use of outdated and ineffective work procedures which were often not followed. Technical failings included a blowdown drum that was of insufficient size, a lack of preventative maintenance on safety critical systems, inoperative alarms and level sensors in the ISOM process unit and the continued use of outdated blowdown drum and stack technology when replacement with the safer flare option had been a feasible alternative for many years.
BP was charged with criminal violations of federal environmental laws, and has been named in lawsuits from the victims' families. The Occupational Safety and Health Administration gave BP a record fine for hundreds of safety violations, and in 2009 imposed an even larger fine after claiming that BP had failed to implement safety improvements following the disaster. In 2011 BP announced that it was selling the refinery as part of its ongoing divestment plan to pay for ongoing compensation claims and remedial activities following the Deepwater Horizon disaster in 2010. The sale of the refinery was completed at the start of 2013 to Marathon Petroleum Corporation for $2.5 Billion. 
The refinery was built in 1934, but had not been well maintained for several years. Consulting firm Telos had examined conditions at the plant and released a report in January 2005 which found numerous safety issues, including "broken alarms, thinned pipe, chunks of concrete falling, bolts dropping 60ft and staff being overcome with fumes." The report's co-author stated, "We have never seen a site where the notion 'I could die today' was so real." The refinery had also had five managers in the six years since BP inherited it in its 1999 merger with Amoco.
The ISOM plant isomerization at the site was designed for the conversion of low octane hydrocarbons, through various chemical processes, into higher octane rating hydrocarbons that could then be blended into unleaded petrol. One component of this ISOM site was a unit called the raffinate splitter. When operational, this 170-foot tall tower was used to separate out lighter hydrocarbon components from the top of the tower (mainly pentane and hexane), which condensed and were then pumped to the light raffinate storage tank, whilst the heavier components were recovered lower down in the splitter then pumped to a heavy raffinate storage tank. It had an operational capacity of 45,000 barrels per day (bpd).
Remedial works had started on the raffinate splitter from 21st, February 2005, two other turnaround  activities were also taking place at the adjacent Ultracracker Unit (UCU) and at the Aromatics Recovery Unit (ARU) at the same time.
1n 1995 and again in 2002, site-wide temporary siting analysis reports had been created at the facility which established the agreed layout of trailers and other temporary structures. The next siting analysis was due to take place in 2007 and therefore any siting changes before then would be under the management of change (MOC) process. Plans were made late in 2004 to accommodate contractors due to work on the UCU in 2005 in nine single trailers and a single double-wide trailer adjacent to the ISOM process unit. Although the team carrying out this assessment had identified that the double-wide trailer would be less than 350 feet from the ISOM plant (and therefore had the potential to be susceptible to severe damage in the event of an explosion), they did not have the expertise to complete the Amoco workboat siting analysis which was based upon the American Petroleum Institute standard ‘API 752’.  A number of action items were created from this assessment, and according to the procedure, these had to be closed before the MOC could be approved and prior to the double-wide trailer being used. These two actions were still pending in March, 2005 but nevertheless, the double-wide trailer had already been in use by contractors from November, 2004. The remaining nine UCU contractor trailers arrived on site at the start of 2005, but these had not been included in the 2004 MOC, so the additional exposure risk of these new trailers being occupied in close proximity to the ISOM plant was never assessed.
After works had been completed on the raffinate splitter, consideration was given to the impending start-up of the plant. One of the primary safety critical steps in the prestart-up process was the use of the BP Pre-Startup Safety Review (PSSR) procedure. The purpose of the review was to ensure that complete and thorough technical checks were carried out and that all non-essential personnel were clear during the start-up operation. Once completed, the PSSR would be signed off by refinery operations and safety managers, authorising the start-up work but this essential safety procedure was not completed.  In addition, there were a number of serious issues with items of safety critical equipment which had not been resolved prior to the start-up commencing including an inoperative pressure control valve (PV-5002), a defective high level alarm in the splitter tower (LSH-5102), a defective sight glass used to indicate fluid levels at the base of the splitter tower and the vital splitter tower level transmitter had not been calibrated.
Nevertheless, the start-up process commenced with the Night Lead Operator on the 22nd, March with the initial filling of the splitter tower. The level transmitter was designed to indicate the raffinate level within a 5 feet span from the bottom of the splitter tower to a 9 feet level (i.e. 72% level indication would be 7.6 feet from the bottom) but it was common practice to fill up to an indicated level of 99% even though the procedural requirement was stated as 50%. The Day Supervisor arrived late for work and didn’t have a hand-over with the night shift. During the morning meeting on the 23rd, March it was discussed that the heavy raffinate storage tanks were nearly full and therefore the second Day Supervisor was told that the start-up procedure should not continue but this information was not passed on. The start-up procedure resumed at just before 09:30am under instructions from the other Day Supervisor. Before recommencing the tower refill and circulation process, heavy raffinate was drained from the bottom of the tower via the level control valve into the heavy storage tank and was then shut off in ‘manual’ mode and not the required ‘automatic’ mode with a 50% flow rate. At just before 10:00am, the circulation process was restarted and raffinate was once again fed into the tower, even though the level was already too high. Since the level control valve was shut and therefore there was no circulation out of the tower (i.e. no heavy raffinate being transferred to the storage tank), the splitter tower inevitably began to fill up. The defective level transmitter continued to show the level at less than 100% and since the external sight glass was opaque, a visual check to verify the level in the splitter tower was not possible.
Burners in the furnace were turned on to pre-heat raffinate going into the tower and to heat the raffinate in the tower bottom, two more were lit at 11:16am. The required temperature for the tower reboiler return flow was 135°C at 10°C per hour but the procedure was not followed. During this start-up, this return flow temperature reached 153°C with a rate increase of 23°C per hour.  The erroneous 93% reading from the defective level transmitter still indicated an ongoing safe level condition in the tower but there was still no flow of heavy raffinate from the splitter tower to the storage tank as the level control valve remained closed; instead of the hydrocarbon liquid level being at 8.65 feet (93% level) as indicated, it had actually reached 67 feet. Just before midday, with heat increasing in the tower, the actual fluid level has risen to 98 feet. Pressure started to build up in the system as the remaining nitrogen in the tower and associated pipework became compressed with the increasing volume of raffinate. The operations crew thought that the pressure rise was a result of overheating in the tower bottoms as this was a known start-up issue, so the pressure was released.
By 12:42pm, the furnaces had been turned down and the level control valve was finally opened, draining heavy raffinate from the splitter tower. The operators believed the level transmitter reading which was now down to 78% (7.9 feet) but the fluid level in the 170-foot tall splitter tower had now reached 158 feet. Although the raffinate flow in to and out of the tower were now matching (as the heated raffinate was now leaving the bottom of the tower), heat from this outflow was being transferred via a heat exchanger back into the liquid flowing into the tower from the feed pipe, raising the average temperature inside the column close to the liquids boiling point. The liquid, already close to the top of the tower but continuing to expand due to the heat, finally entered the overhead vapour line and flowed into the relief valve system.
Pressure built up in the system as fluid filled the pipework running to the safety relief valves and the condenser. At 1:13 pm, the three pressure relief valves were activated as the hydrostatic head pressure of the raffinate built to over 60 psig.  With the relief valves fully open, over 196,000 litres of heated raffinate passed directly into the collection header over a 6 minute period before closing, as pressure in the system dropped to their closing or blowdown pressure of 37.3 psig in the system.
Investigating this pressure spike, the Day Board Operator fully opened the level control valve to the heavy raffinate storage tank and shut off of the gas fuelling the furnace, but the raffinate feed into the splitter tower was not shut off. Hot raffinate flowed into the blowdown drum and stack and as it filled, some of the fluid started to flow into the ISOM unit sewer system via a 6-inch pipeline at the base of the blowdown drum. As the blowdown drum and stack filled up, liquid overflowed out of the top of the stack forming a 20 foot ‘geyser’  as hot hydrocarbon liquid vented directly into the air. It then ran down the side of the blow-down drum and stack and pooled at the base of the unit. A radio call was received in the control room that hydrocarbons were overflowing from the stack. A pick-up truck, with its engine running had been parked within 30 feet of the blowdown stack. The vapour cloud reached the vehicle, causing the engine to race. The cloud continued to spread across the ISOM plant, across the pipe-rack to the West and into the trailer area. No emergency alarm sounded and at approximately 1:20pm, there was a catastrophic vapour cloud explosion, probably ignited by the hot car engine.  The blast pressure wave struck the contractor trailers, the force of the explosion sent debris flying, causing fatal blunt force trauma to 15 people in and around the trailers, 180 others were injured. The pressure wave was so powerful it shattered windows off site up to a distance of three-quarters of a mile away. An area estimated at 18,581 square metres (approximately 200,000 square feet) was burned. 
The CSB report found that BP had failed to heed or implement safety recommendations made before the blast. Among them were:
- In 1991, the Amoco refining planning department proposed eliminating blowdown systems that vented to the atmosphere, but funding for this plan was not included in the budget.
- In 1992, OSHA issued a citation to Amoco for unsafe design of similar pressure-relief systems at the plant. However, Amoco successfully persuaded OSHA to drop this citation by relying on the less-stringent requirements in API Recommended Practice 521.
- In 1993, the Amoco Regulatory Cluster project proposed eliminating atmospheric blowdown systems, but again, funding was not approved.
- In 1995, a refinery belonging to Pennzoil suffered a disaster when two storage tanks exploded, engulfing a trailer and killing five 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 where most of the deaths happened was empty most of the year, the risk was low.
- Despite Amoco’s process safety standard No. 6, which prohibited new atmospheric blowdown systems and called for the phasing out of existing ones, in 1997, Amoco replaced the 1950s-era blowdown drum/vent stack that served the raffinate splitter tower with an identical system, instead of upgrading to recommended alternatives that were safer.
- In 2002, engineers at the plant proposed replacing the blowdown drum/vent system as part of an environmental improvement initiative, but this line-item was cut from the budget, due to cost pressures.
- Also in 2002, an opportunity to tie the ISOM relief system into the new NDU flare system was not taken, due to a $150,000 incremental cost.
- During 2002, BP’s Clean Streams project proposed converting the blowdown drum to a flare knock-out tank, and routing discharges to a flare. When it was found that a needed relief study of the ISOM system had not been completed due to budget constraints, the Clean Streams project proposed adding a wet/dry system to the ISOM instead.
- Between 1994 and 2004, at least eight similar cases occurred in which flammable vapors were emitted by a blowdown drum/vent stack. Effective corrective action was not taken at the BP plant.
As a result of the accident, BP said that it would eliminate all blowdown drums/vent stack systems in flammable service. The CSB, meanwhile, recommended to the American Petroleum Institute that guidelines on the location of trailers be made.
OSHA ultimately found over 300 safety violations and fined BP $21 million—the largest fine in OSHA history at the time.
Legal action 
On February 4, 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. The judge gave no timetable on when she would make a final ruling.
On October 30, 2009, OSHA imposed an $87 million fine on the company for failing to correct safety hazards revealed in the 2005 explosion. In its report, OSHA also cited over 700 safety violations. The fine was the largest in OSHA's history, and BP announced that it would challenge the fine.
On August 12, 2010, BP announced that it had agreed to pay $50.6 million of the October 30 fine, while continuing to contest the remaining $30.7 million; the fine had been reduced by $6.1 million between when it was levied and when BP paid the first part.
Subsequent incidents 
After the March explosion, other safety incidents occurred at the plant:
- On July 28, 2005, a hydrogen gas heat exchanger pipe on the resid hydrotreater unit ruptured, causing a release of hydrogen that erupted into a large fireball. One person received minor injuries. The Chemical Safety Board found that a contractor had accidentally switched a carbon steel pipe elbow with a low-alloy steel elbow during maintenance, causing a failure mode known as “high temperature hydrogen attack” (HTHA).
- On August 10, 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 valve that handles high-pressure gas and oil.
- On January 14, 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.
- On September 21, 2010, an incident in the Pipestill 3B unit left two workers with serious steam burns. The details of this incident are still under investigation.
Baker panel 
Following the 2005 incidents, on August 17, 2005, the CSB recommended that BP 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 January 16, 2007.
The Baker report cited a weak safety culture, and reported that BP did not adequately follow the Department of Energy's published safety recommendations. The report suggested that cost-cutting and production pressure from BP executives may have resulted in a lack of needed safety measures across the board Carolyn W. Merritt, Chairman and Chief Executive Officer of the CSB stated, "The combination of cost-cutting, production pressures, and failure to invest caused a progressive deterioration of safety at the refinery. Beginning in 2002, BP commissioned a series of audits and studies that revealed serious safety problems at the Texas City refinery, including a lack of necessary preventative maintenance and training. These audits and studies were shared with BP executives in London, and were provided to at least one member of the executive board. BP's response was too little and too late. Some additional investments were made, but they did not address the core problems in Texas City. In 2004, BP executives challenged their refineries to cut yet another 25% from their budgets for the following year." In addition, inadequate safety improvements between 2002 and 2005 were "largely focused on personal safety - such as slips, trips, falls, and vehicle accidents, rather than on improving safety performance," according to Supervisory Investigator Don Holstrom.
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, located in Birch Bay, Washington, had the best process safety culture. The survey results also showed that managers and white-collar workers generally had a more positive 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.
Popular culture 
- The explosion was featured on History Channel's series Modern Marvels, on Season 12, episode 47 "Engineering Disasters 20."
- The explosion was also featured on National Geographic's television series Seconds From Disaster, on the episode "Texas Oil Explosion".
See also 
- "U.S. Refineries* Operable Capacity". Department of Energy, Energy Information Administration. July 2008.
- The merger date is variously listed as either 1998 and 1999 depending on the source. The reason for this confusion is that the deal was signed at 21:00 hours GMT on the 31st, December, 1998 in London but the new stock wasn't traded until start of business on the 4th, January 1999. In reality the newly formed company started its operations at the start of 1999.
- BP completes Texas City refinery sale to Marathon Petroleum http://www.bizjournals.com/houston/news/2013/02/01/bp-completes-texas-city-refinery-sale.html
- BP Fatal Accident Investigation Report -Isomerization Unit Explosion Final Report, Texas City, Texas, USA. 9th, December 2005, Executive Summary
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005,
- "OSHA Fines BP Products North America More Than $21 Million Following Texas City Explosion". US Department of Labor. 22 September 2005. Retrieved 23 March 2013.
- "US Department of Labors OSHA issues record-breaking fines to BP". US Department of Labor. 30 October 2009. Retrieved 23 March 2013.
- BP Completes Sale of Texas City Refinery and Related Assets to Marathon Petroleum http://www.bp.com/genericarticle.do?categoryId=2012968&contentId=7084789
- "BP's Troubled Past". The Spill. Frontline, PBS.org. 26 October 2010. Retrieved 23 March 2013.
- Lyall, Sarah. In BP’s Record, a History of Boldness and Costly Blunders. New York Times, July 13, 2010.
- A turnaround in general terms is a planned large scale maintenance operation, normally closing down an entire process unit whilst remedial works, modifications and upgrades are carried out.
- API 752 – “Management of Hazards Associated with Locations of Process Plant Buildings, 1995”
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005, para 18.104.22.168, p47
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005, para 2.5.6, p55
- Psig is defined as ‘pounds per square inch gauge’ which indicates a pressure relative to atmospheric pressure.
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005, para 2.5.11, p62
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005, para 2.5.13 Ignition Source, p66
- U.S. Chemical Safety and Hazard Investigation Board. Investigation Report - Refinery Fire and Explosion and Fire. BP Texas City March 23, 2005, p64
- Baldwin, Lisa (February 4, 2008). "BP Explosion Victims' Relatives Oppose Plea". Click2Houston.com. Retrieved February 4, 2008.
- Lozano, Juan A. (February 4, 2008). "Judge mulls BP plea in Texas plant blast". Associated Press. Retrieved February 5, 2008.
- Greenhouse, Steven (October 30, 2009). "BP to Challenge Fine for Refinery Blast". New York Times. Retrieved November 1, 2009.
- "BP agrees to pay record $50.6m fine for Texas explosion". BBC News. August 12, 2010. Retrieved August 15, 2010.
- Flood, Mary (January 17, 2008). "Agency to investigate death at BP refinery". Houston Chronicle. Retrieved January 18, 2008.
- "CSB Issues Urgent Safety Recommendation to BP Global Board, Calls for Creation of Independent Panel to Examine Corporate Safety Management, Oversight, and Safety Culture". US Chemical Safety Board. 17 August 2005. Retrieved 23 March 2013.
- "U.S. Chemical Safety Board Concludes "Organizational and Safety Deficiencies at All Levels of the BP Corporation" Caused March 2005 Texas City Disaster That Killed 15, Injured 180". US Chemical Safety Board. Retrieved March 23, 2013.
- Mufson, Steven (17 January 2007). "BP Failed on Safety, Report Says". The Washington Post. Retrieved 23 March 2013.
- "Safety Culture Weakness Cited in BP Accident, Department of Energy Office of Health, Safety, and Security Safety Advisory No. 2007-02". Department of Energy. April 2007. Retrieved March 23, 2013.
- "CSB Final Investigation Report on the BP Texas City Refinery Explosion and Fire, Section 1.6 Key Organization Findings, Pg. 25". CSB Final Investigation Report on the BP Texas City Refinery Explosion and Fire. ProPublica. January 2007. Retrieved 23 March 2013.
- US Chemical Safety Board
- BP: Texas City Refinery Incident – March 23, 2005
- BP Accident Investigation Report
- Baker Panel Report
- Chemical Safety Board Investigation Status Page
- Brent Coone website – hosts documents released to the public by BP as one of the terms of settlement with Eva Rowe
- Special Report: 2005 Texas City Explosion. Houston Chronicle.
- Lessons from Texas City: A case history, Loss Prevention Bulletin, Issue 192, 2006, IChemE, UK.
- Remember the 15 Memorial site for those lost in the explosion with ongoing info on the aftermath.