The U.S. Chemical Safety Board today issued urgent safety recommendations calling on refiner CITGO to immediately improve its emergency water mitigation system in the event of another release of potentially deadly hydrogen fluoride vapor, as occurred following an explosion and fire July 19, 2009, at the company’s Corpus Christi refinery, according to a news release.

The CSB also called on CITGO to perform third-party audits to ensure the safety of its hydrogen fluoride units at its refineries in Corpus Christi and Lemont, Illinois.

The CSB issues urgent recommendations before completion of final investigation reports in cases where 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 accident last July, hydrocarbons and hydrogen fluoride were suddenly released from the refinery’s hydrogen fluoride or HF alkylation unit. The hydrocarbons ignited, leading to a fire that burned for several days. The fire critically injured one employee, while another was treated for 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 hydrogen fluoride, but the CSB cited scientific literature to conclude that 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.

Approximately 11-1/2 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 call on CITGO to develop and initiate plans within 30 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 30 days until all planned activities are fully implemented.

“Our investigation closely examined emergency response actions related to this accident,” said investigations supervisor Robert Hall. “Investigators found that 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, Texas, HF water mitigation system.”

The Board also recommends that CITGO commission independent, third-party audits of the safety of its two HF alkylation units at refineries in Corpus Christi and Lemont. The audits should compare safety practices at the alkylation units to those recommended by the American Petroleum Institute. Investigators said that 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 and fire as captured by two refinery surveillance cameras. Bresland noted that the camera footage shows the release and spread of the flammable vapor cloud and the moment when the flammable vapor was ignited. It shows just how severe the release and fire were during the incident.

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 regulations, industry standards, and safety management systems.

The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as Occupational Safety and Health Administration or OSHA and the Environmental Protection Agency or EPA.