CITGO refinery fire investigation

Monday, May 10, 2010 @ 03:05 PM gHale


A July 19 fire last year in the alkylation unit at CITGO’s 163,000 barrel per day Corpus Christi, TX, refinery resulted in a worker suffering from critical burns and the release of hydrofluoric acid (HF). The alkylation unit makes high-octane blending components for gasoline.
The U.S. Chemical Safety Board (CSB) issued urgent safety recommendations calling on CITGO to immediately improve its emergency water mitigation system in the event of another release of potentially deadly hydrogen fluoride (HF) vapor, as occurred following an explosion and fire last July. The CSB also called on CITGO to perform third-party audits to ensure the safety of its hydrogen fluoride units at its Corpus Christi, TX, and Lemont, IL refineries.


The CSB issues urgent recommendations before completion of final investigation reports in cases where CSB Board Members determine an imminent hazard may be present and has the potential to cause serious harm unless rectified in a short timeframe.
On the day of the July accident, hydrocarbons and hydrogen fluoride suddenly released from the refinery’s HF alkylation unit. The hydrocarbons ignited, leading to a fire that burned for several days. The fire critically injured one employee and another suffered from possible hydrogen fluoride exposure.
CSB investigators determined that a blockage of liquid caused by the sudden failure of a control valve led to violent shaking within the process recycle piping. The shaking broke threaded pipe connections resulting in the release of hydrocarbons. The cloud of hydrocarbons reached an adjacent unit and ignited. The ensuing fire caused multiple additional fires and the release of approximately 42,000 pounds of hydrogen fluoride from equipment and piping within the unit.
The refinery used a water spray system to absorb the released HF, but the CSB cited scientific literature to conclude at least 4,000 pounds of HF likely escaped from the unit into the atmosphere and left the facility. Investigators determined that during the first day of response efforts CITGO nearly exhausted the stored water supply for the water mitigation system. About 11½ hours after the initial release, before the water supply was completely exhausted, the refinery began pumping salt water from the ship channel into the refinery fire water supply. Multiple failures occurred during the salt water transfer including ruptures of the barge-to-shore transfer hoses and water pump engine failures.
“It is imperative that refineries have the proper emergency response resources available to control a release of hazardous materials and protect against impact on the surrounding community,” said CSB Chairman John Bresland.
The CSB’s urgent recommendations called on CITGO to develop and initiate plans within thirty days to ensure an adequate water supply to the refinery’s HF mitigation system. The company should also report planned or completed actions to the Refinery Terminal Fire Company and the Local Emergency Planning Committee every thirty days until all planned activities are in full implementation.
“Our investigation closely examined emergency response actions related to this accident,” said Investigations Supervisor Robert Hall, P.E. Investigators found the CITGO water mitigation system serves as the last line of defense to protect the community from an HF release. The CSB’s urgent recommendation aims to improve the reliability of CITGO’s Corpus Christi, TX, HF water mitigation system.”
A second urgent recommendation called on CITGO to commission independent, third-party audits of the safety of its two HF alkylation units at refineries in Corpus Christi and Lemont, IL. The audits should compare safety practices at the alkylation units to those recommended by the American Petroleum Institute (API). Investigators said CITGO had never conducted such an audit of the units, despite an existing industry recommendation for audits every three years.
The CSB also released video of the initial pipe failure, release, ignition, and fire as captured by two refinery surveillance cameras. “The camera footage shows the release and spread of the flammable vapor cloud and the moment when the flammable vapor was ignited,” Bresland said. “It shows just how severe the release and fire were during this incident.”


CSB investigation video

The company, Bresland said, objected to the CSB’s release of the video, saying doing so would “raise substantial issues of national security” and would “only sensationalize this unfortunate accident.” The CSB subsequently received affirmation from the Department of Homeland Security the video did not fall under certain classifications requiring protection from disclosure.
“We found this claim disturbing and believe that it is contrary to the intent of a recent law passed by Congress … ,” Bresland said. “This law, the American Communities’ Right to Public Information Act, states that national security classifications may not be used to conceal corporate errors, prevent embarrassment, or improperly delay the release of information to the public. An important part of this CSB investigation is to ensure all relevant information and visual materials regarding this accident are made available to the residents of Corpus Christi.”
The CSB is an independent federal agency charged with investigating industrial chemical accidents. The President of the United States appoints the agency’s board members and then the Senate confirms them. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems.



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