CSB issues urgent recommendations in probe of Citgo refinery fire

The US Chemical Safety Board issued urgent safety recommendations to Citgo Petroleum Corp., calling on the refiner to immediately improve the emergency water system at its Corpus Christi, Tex., refinery and to perform third-party audits of hydrogen fluoride (HF) units there and at its Lemont, Ill., refinery.

Nick Snow
OGJ Washington Editor

WASHINGTON, DC, Dec. 10 -- The US Chemical Safety Board issued urgent safety recommendations to Citgo Petroleum Corp., calling on the refiner to immediately improve the emergency water system at its Corpus Christi, Tex., refinery and to perform third-party audits of hydrogen fluoride units there and at its Lemont, Ill., refinery.

Citgo said in a statement the same day that it appreciated CSB’s “thorough and ongoing investigation” and that it has already taken action on the board’s recommendations.

The federal agency took the action as it continued investigating a July 19 explosion and fire from hydrocarbons that were released along with potentially deadly HF vapor. CSB issues urgent recommendations before final investigations are completed in cases where board members determine an imminent hazard may be present and it has the potential to cause serious harm unless promptly rectified.

It noted that on the day of the accident, hydrocarbons and HF were suddenly released from the HF alkylation unit at Citgo’s 163,000-b/d Corpus Christi plant. The hydrocarbons ignited, leading to a fire that burned for several days and critically injured one employee.

CSB said its 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, which broke threaded pipe connections and released a hydrocarbons cloud. That cloud reached an adjacent unit and ignited, causing multiple additional fires and the release of approximately 42,000 pounds of HF from equipment and piping within the unit.

CSB said the refinery used a water spray system to absorb the released HF, but added that at least 4,000 lb likely escaped into the atmosphere. Citgo said its own engineering calculations of how much HF was released were based on thousands of its own air monitoring samples as well as US Environmental Protection Agency data and a rigorous mass balance.

Supply ran low
Investigators determined that during the first day of response, Citgo nearly exhausted the water mitigation system’s stored supply and began pumping salt water from the ship channel into the refinery’s water supply about 11½ hr after the initial release, according to CSB. It said that investigators found that multiple failures occurred during the saltwater transfer, including ruptures of the barge-to-shore transfer hoses and water pump engine failures.

“Investigators found that the Citgo water mitigation system serves as the last line of defense to protect the Corpus Christi community from an HF release,” CSB Investigations Supervisor Robert Hall said.

CSB’s urgent recommendations call on Citgo to develop and initiate plans within 30 days to ensure that the refinery’s HF mitigation system has an adequate emergency water supply. They also ask the company to report planned or completed actions to the refinery terminal fire company and local emergency planning committee every 30 days until all planned activities are fully implemented.

An additional urgent recommendation called on Citgo to commission independent, third-party audits of its two HF alkylation units at the Corpus Christi refinery and its 167,000 b/d plant in Lemont. CSB said the audits should compare safety practices at the alkylation units to those recommended by the American Petroleum Institute. Investigators said Citgo has never conducted such an audit of the units despite an existing industry recommendation for audits every 3 years.

Video released
The federal agency 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,” said CSB Chairman John S. Bresland. “It shows just how severe the release and fire were during this incident.”

He noted that the company objected, saying that releasing the information would raise substantial national security issues and sensationalize the accident. CSB subsequently received affirmation from the US Department of Homeland Security that the video did not fall under classifications requiring protection from disclosure. It is available online at CSB’s web site, www.chemsafety.gov.

Bresland cited a law passed by Congress following secrecy claims by Bayer CropScience in Institute, W.Va. The American Communities’ Right to Public Information Act, he said, “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.”

Contact Nick Snow at nicks@pennwell.com.

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