BP Texas City Refinery 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. An explosion and fire occurred at Texas City refinery on March 23, 2005. A series of explosions occurred at the BP Texas City refinery during the restarting of a hydrocarbon isomerization unit. It is one of the most serious industrial incidents in the past two decades.
2) OUTLINE OF THE ACCIDENT:
On 23 March, 2005, 15 people were killed and 180 people injured due to an explosion and fire in BP Texas City Refinery. The accident happened when refinery personnel tried to start up the raffinate splitter tower in the refinery's isomerisation unit after a maintenance shutdown. During the Start up Operation of the ISOM Unit, the operations personnel pumped flammable liquid hydrocarbons into the tower for over three hours without any liquid being removed. The operators of the high level in the tower failed to alert due to the false indications provided by the Critical alarms and control instrumentation.
Due to the accident refinery processes were damaged, the trailers were destroyed and the offsite property was also damaged. The incident occurred due to the overfilling of Tower and Blowdown Drum and the release of the Liquid Hydrocarbon. As a result of this explosion Vapour Cloud was formed and ignited. Due to the significance of the disaster, the U.S. Chemical Safety and Hazard Investigation Board (CSB) investigated not only BP'S safety performance at Texas City, but also the role played by BP Group. The Texas Disaster occurred due to the deficiencies in the Organisational and Safety procedures.
3) ENVIRONMENTAL IMPACT:
Environmental Justice is the right to a decent, safe quality of life for people of all races, incomes and cultures in the environments where we live, work, play, learn and pray. A shelter-in-place order was issued that required 43,000 people to remain indoors. Houses were damaged as far away as three- quarters of a mile from the refinery. There should be minimum exposure to the hazardous effects of the chemicals. Public has been evacuated to avoid danger in times of emergency. Sirens are used to inform the neighbours in case of any emergency in the refinery. The Community Warning System activates the Emergency Alert System, contacts with the media, and people with Weather Radios receive the message to shelter-in-place.
The gases that are released may cause a pre-existing breathing condition, like asthma. The health can have a long term impact which is based upon the direction of the wind and the flow of the air during the incident. The long term health impact has been found to be low due to the dilution of hazardous materials. An Investigation was held by the U.S. Chemical Safety and Hazard Investigation Board where 370 interviews were conducted and over 30,000 documents were reviewed. Various equipments and instruments were also tested during the investigation.
4) REASONS FOR THE CAUSE OF THE EXPLOSION:
The main reasons for the cause of the explosion are
- Human Errors
- Operators Deviated from the Procedures
- Supervisors and Managers did not correct Procedural Deviations
- Communications was ineffective between Operations Personnel
- Tower Instruments Malfunctioned
- Operators were likely Fatigued
- Supervisor and Operator Staffing was Insufficient
- Operator Training was not effective
4.1) Human Errors
Human Error was the cause for the overfilling of the Tower. Human Errors are the symptoms of underlying errors. The Operational Procedures were not followed correctly. The instrumentation also gave some misleading information.
4.2) Operators Deviated from the Procedures
The Operational Procedure is required that the Tower Level Control Level must be placed in automatic mode to control the level at 50 %.The board operator placed the tower level control valve in manual mode.
4.3) Supervisors and Managers did not correct Procedural Deviations
The procedure followed did not reflect the actual practice. The Start up Procedure lacked sufficient instructions. In the Operational Procedure the hazards of high tower level were not identified.
4.4) Communications was ineffective between Operations Personnel
There was no proper communications between the operational personnel. BP also had no policy for effective communication between the operational personnel.
4.5) Tower Instruments Malfunctioned
The Level Transmitter in the Tower was miscalibrated which gave the operators false readings. No other indications regarding the level were available to the operators.
4.6) Operators were likely Fatigued
The Operators worked 12 hrs shifts continuously for 7 days a week. There was no sufficient sleep for the operators. BP has no regulation for maximum shift work.
4.7) Supervisor and Operator staffing was Insufficient
The unit Start Up was hazardous and it required more Supervisors. No Supervisor or technically trained person with ISOM experience assisted during Start Up's.
4.8) Operator Training was not effective
There was no effective training given to the operators. The Simulation Technology was not available.
5) CLEAN UP:
When a Liquid Hydrocarbon is spilt in a refinery due to an accident, The 3 options which I use is
- Mechanical Recovery
- Chemical Dispersion
- Do Nothing
5.1) Mechanical Recovery
The Mechanical Recovery involves using Booms and Skimmers. We know that oil moves at 100% of current speed and 3% of wind speed. Booms are limited by wave and current conditions. Liquid can be recovered using skimmers. The Skimmers are subject to the equipment availability and disposal of the liquid.
The different types of skimmers used are
- Belt Skimmers
- Oleophilic Rope Skimmers
- Disc Skimmers
- Weir Skimmers
- Vortex Skimmers
- Air Suction Skimmers
5.2) Chemical Dispersion
Chemical Dispersion is by applying dispersants from aircraft and boats. Dispersants are said to be effective few days after the spill before the viscosity of the oil rises. Dispersants can cause toxicity to some habitats like coral reefs.
5.3) Do Nothing
Do nothing mean that the liquid itself will evaporate and we should wait for it.
6) PREVENTIVE MEASURES:
The preventive measures that should be adopted to prevent further accidents and disaster are
- Improve the training skills of the operator with face to face instruction and simulation technology.
- The Operational procedures should be updated reflect the actual process conditions.
- The Start Up, Shut Down and abnormal conditions require additional board operator staffing.
- During hazardous operation knowledgeable supervisors or other technically trained personnel should be present.
6.1) Inspection & Maintenance of process instrumentation
In process instrumentation and control systems various strict inspection strategies must be adopted. Many approaches like risk-based, reliability-based and availability-based inspection approaches must be maintained.
There should be a closed relief system that has maximum blow down capacity; harmful chemicals must be vented into the open atmosphere. Checking should be performed periodically as venting is a safety-critical process.
6.3) Interactive Risk Management
The unit experiences incidents or near misses can be determined through incident precursors or near miss data in risk estimation which will enable precise and dynamic risk values.
6.4) Process safety management (PSM)
Process safety management (PSM) system is used for process safety decisions and activities. Such systems must incorporate the essential management functions of plan, do, and check and act to be effective.
Any developments must be analysed with reference to occupied buildings, mobile equipment, temporary facilities, and emergency muster points to ensure that personnel are located appropriately. An emergency response plan should be developed and tested to ensure its ease of implementation.
6.6) Risk awareness
Risk awareness brings a better understanding of the need to identify, control and eliminate process-related risks. It also creates a safety culture appropriate for the activities that are undertaken.
6.7) Inherent safety awareness
This is a proactive approach to ensuring process safety. Undesired events can be prevented by safety principles in design and operations. The principles protect life, assets, production time, and the environment. The safety principles should be implemented in operations personnel's daily activities.
The core value of Oil and Gas Industry is Safety and reliability. Health Services should activate The Community Warning System should be regularly checked by Health Services for any of the refineries and many of the chemical plants in the country. The U.S. Chemical Safety and Hazard Investigation Board should conduct inspections in the companies about the safety measures, clean up process of the plant. It should even look to the protection mechanisms undertaken for the welfare of the workers and neighbours. Periodic reports can be generated to the public for the awareness.
2. http://www.csb.gov/completed_investigations/docs/BP_Public_Meeting_Ppt_03202007. Pdf