Refinery Acid Leaked for 5 Months

Tuesday, March 20, 2012 @ 06:03 PM gHale

An alkylation unit at Citgo Petroleum Corp.’s Corpus Christi refinery was leaking for five months before spilling as much as 500 pounds of the hydrofluoric acid on March 5, the U.S. Chemical Safety Board (CSB) said.

Leaks from a flange on the unit occurred as early as September, said Johnnie Banks, lead investigator for the board. The release persisted after maintenance and the unit was kept online while a clamp underwent a redesign, he said.

Hydrofluoric Acid Leak at Citgo Plant
Worker Dies after Refinery Flash Fire
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Over Pressurized Pipe Blows Up

Water cannons automatically went into action to contain the chemical release, Citgo said March 6.

“The facility is routinely using the water cannons as release mitigation for maintenance activities when in reality they should not be used as the last line of defense,” Banks said in the statement.

“Unfortunately, this is not the first time that the CSB has deployed to an incident involving the release of HF at this facility,” Banks said. “On July 19, 2009, an intense hydrocarbon flash fire resulted in a release of hydrofluoric acid in the same process unit as the March 5 incident. The fire, which burned for several days, critically injured one employee and another was treated for possible HF exposure. As a result of the 2009 accident, Citgo reported to the Texas Commission on Environmental Quality that approximately 21 tons of HF released from alkylation unit piping and equipment.

“To date, our investigation has found that the March 5th release can be traced to leaks at this flange reported as far back as September 2011. In late January of this year, maintenance was performed on the flange, tightening the existing bolts, but the leak persisted. Further maintenance was performed on February 10 – over three weeks prior to the actual incident. At that time workers replaced the flange bolts and a work order was submitted to order a clamp to enclose the leak.

“The unit was not shut down; rather the clamp was ordered in the hopes that its installment would stop the leak. The proposed design of the new clamp was rejected three times over the next three weeks and had not been installed by March 5.

“On the day of the incident the leak from the piping flange on the 12-inch line worsened. Process liquids containing hydrocarbons and about 5% HF were released in a steady stream which worsened through the late afternoon.”

Citgo was not immediately available for comment.

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