Article Archive
HF Release
CSB deploys to investigate hydrofluoric acid release at Corpus Christi, TX, refinery
Vol. 27 Spring 2012

UPDATE Washington, DC,  March 12, 2012 - Three CSB investigators will be returning to the CITGO East Refinery in Corpus Christi, TX, today to continue investigating the March 5 release of highly toxic hydrofluoric acid (HF) from the refinery’s alkylation unit.  A seven-person CSB team was deployed to the refinery last week following the release, which occurred at about 7 p.m. Monday, March 5. 

Investigators will be returning to the facility to conduct follow up interviews with plant personnel and further examine the unit. 

To date the team has determined that the incident occurred during a leak from a piping flange on a 12-inch line operating at 145 pounds per square inch gauge (psig).  The released process stream contained hydrocarbons and about 5% HF, according to refinery officials.  The release triggered the alkylation unit’s automatic water cannons, designed to capture airborne HF. 

Last week the CSB designed and conducted a test on the failed flange intended to determine the leak rate.  The line was pressured up with nitrogen gas and the rate of depressurization measured.  CSB investigators are currently calculating the estimated size of the release using the test data.  Investigators will also be examining several failed bolts that were recovered from the flange, reviewing key data from the process control system, and examining records of previous releases of HF from the flange and other locations in the alkylation unit.

Washington, D.C., March 6, 2012 - A seven-person investigation team from the U.S. Chemical Safety Board (CSB) is deploying to the site of an accident reportedly involving the release of hydrofluoric acid (HF) at the CITGO Corpus Christi, Texas alkylation unit.  

The team will be headed by Donald Holmstrom, director of the CSB’s Western Regional Office in Denver, and is expected to arrive tonight and begin work Wednesday.

According to media reports, no injuries were reported as detectors sensing the HF set off water cannons to contain the acid release.     

The alkylation unit in the 163,000 barrel a day refinery utilizes HF to make high-octane blending components for gasoline. HF is highly corrosive and toxic.  Absorption through the skin can produce fatal cardiac arrest and inhalation causes damage to the linings of the lungs.  

On July 19, 2009, hydrocarbons and hydrogen fluoride were suddenly released from the same unit. The hydrocarbons ignited, leading to a fire that burned for several days.  The fire critically injured one employee and another was treated for possible hydrogen fluoride exposure.

CITGO reported to the Texas Commission on Environmental Quality that approximately 21 tons (42,000 pounds) of HF released from alkylation unit piping and equipment, but was captured by the HF water mitigation system.

The CSB’s investigation into this accident is continuing.  Investigators early on determined that during the first day of response efforts, CITGO nearly exhausted the stored water supply for the water mitigation system, causing the refinery to begin pumping salt water as a backup.  Multiple failures occurred during the salt water transfer including ruptures of the barge-to-shore transfer hoses and water pump engine failures. 

In December 2009, the CSB issued urgent safety recommendations calling on CITGO to immediately improve its emergency water mitigation system in the event of another release hydrogen fluoride. The Board also called on CITGO to perform third-party audits to ensure the safety of its hydrogen fluoride units at its Corpus Christi, Texas, and Lemont, Illinois, refineries.  CITGO met the requirements of the recommendations and the Board closed them as “Acceptable Action” in 2011.

CSB Chair Rafael Moure-Eraso said, “We are launching an investigation into this accident as we continue our investigation of the 2009 HF release event, because of the toxic nature of hydrofluoric acid and the need to keep it contained, or to mitigate the consequences of a release. Approximately fifty of the nation’s refineries still use HF in their alkylation units, requiring great care in its handling.”    

The CSB is an independent federal agency charged with investigating serious 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 OSHA and EPA.


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