HF Release at CIGTO refinery-CSB issues update on investigation
March16, 2012, Corpus Christi, TX- The CSB (US Chemical Safety Board) today released an update for the press concerning the status of the ongoing investigation into the hazardous release of Hydrofluoric Acid (HF) at the CITGO refinery in Corpus Christi, Texas, USA. Johnnie Banks, the CSB lead investigator tasked with the investigation released some details of the possible causes of the disaster.
For the original incident report, please read this.
Prima facie it appears that it was a problem of mechanical integrity and failure to replace a chronically troublesome flange that caused not only this particular leak, but previous ones too. Here is the statement reproduced below. For the original please visit http://www.csb.gov
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STATEMENT BY TEAM LEAD JOHNNIE BANKS
Good morning, and welcome to the Chemical Safety Board’s – the CSB’s – media availability.
The CSB is an independent federal agency charged with investigating serious chemical accidents at
refineries, chemical plants and fixed facilities.
My name is Johnnie Banks, Team Lead for the CSB. With me today are Investigators Steve
Cutchen and Mark Wingard.
This morning we will be providing you with an update on our investigation into the March 5,
2012, hydrofluoric acid – also referred to as HF – release at the CITGO refinery in Corpus Christi, Texas.
I would like to note that CITGO has been fully cooperative with the CSB’s investigation.
As most of you know, there were no injuries resulting from the accident but I would like to
emphasize that the CSB takes any accident involving the release of HF very seriously. HF is highly
corrosive and toxic. Absorption through the skin and underlying tissue can produce fatal cardiac arrest
and inhalation causes damage to the linings of the lungs.
Unfortunately, this is not the first time that the CSB has deployed to an incident involving the
release of HF at this facility. On July 19, 2009, an intense hydrocarbon flash fire resulted in a release of
hydrofluoric acid in the same process unit as the March 5th 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.
Since arriving in Corpus Christi on March 6th the CSB investigation teams have conducted about
20 interviews, examined the accident scene and designed testing to estimate the total amount of process
stream that was released to the atmosphere during the March 5th incident.
The March 5th leak occurred due to the failure of the seal on a 12 inch flange on a process vessel
in the Alkylation unit. These photos are a close-up of the flange that failed.
As you can see from the photos the flange is a distinct red color. The paint on the flange turns red
when it comes in contact with even a small quantity of acid. Following a maintenance activity the flange
is washed with a caustic solution which returns it to its original color so that subsequent leaks can be
identified.
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 5th.
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.
The CSB has determined that the March 5th incident resulted in the release of between 300 and
500 pounds of HF.
Eventually, the release was detected by sensors that triggered the alkylation unit’s automatic water
cannons, designed to capture airborne HF. Automatic water cannons are intended as the last line of
defense in the event of a release of HF.
Our investigative team has discovered that the water cannons were once again activated by an HF
release on March 10th and 11th as the refinery was restarting the unit.
The events that took place on March 10th and 11th were planned work activities AND the
company was aware that the water cannons might be triggered.
Although the two additional releases were small in quantity the CSB is concerned that
management accepted that the water cannons could be triggered. The facility is routinely using the water
cannons as release mitigation for maintenance activities when in reality they should only be used as the
last line of defense.
Moving forward the CSB will be examining commonalities between the 2009 HF release and the
March 5th incident. The facility’s continued reliance on the water cannons to “control” an HF release
raises serious concerns regarding the facility’s management systems and control.
The CSB’s investigations seek to identify the root cause of an accident. As new information
becomes available, we will keep the community, public officials and the industry informed. We do all
this, of course, in an effort to prevent serious chemical and refinery accidents that cause injuries, destroy
property, and jeopardize public safety.
Our ultimate product will include safety recommendations designed to prevent a recurrence of this
type of accident, here or at refineries located in cities across the country.
CITGO’s workers and its neighbors have a right to know that their safety is an important
consideration during the daily operations of this refinery.
Thank you for attending today, and we will be happy to answer your questions.
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Ed Note: This underscores that risk assessment techniques such as HAZOP should be regularly used on an ongoing basis to identify risks. However mitigation measures should not become operational controls or protective/preventive measures. Additionally a SIL study should also be carried out. Gas Detection systems should also be regularly tested and calibrated so that their reliability is maintained. In fact if possible, they should be part of the facility’s Safety Instrumented System.
Hydrofluoric Acid release at CITGO facility in Corpus Christi-CSB investigates
UPDATE: Please see the post here for an update on this story
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.
(Ed Note: This is the reason that reliable Gas Detectors are a must in every industrial facility. The cost of the system is far less than the cost of the consequences, had the system not been installed)
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.
As a result of the 2009 accident 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.
(Ed Note again: This is why a proper consequence analysis and worst case scenario planning are a must.Risk assessment studies such as HAZOP and SIL study should take this into account).
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.”
Fieldbus and Safety Instrumented Systems-implementing Safety Instrumented Functions in Fieldbus
Miami Dec 19, 2011- There has been a lot of buzz lately about Safety Instrumented Systems utilizing Fieldbus technology, or rather having Fieldbus systems also have Safety Instrumented System functionality. As those of you in the process industries probably know, Safety Instrumented Systems are special automation and control systems that ensure that plants having hazardous processes will be adequately protected and can be shut down safely in case of any process upsets or untoward incidents. Safety Instrumented Systems protect people, assets and the environment, in case of unwanted deviations, failures of the main process control system or equipment and other undesirable and unplanned events. Safety Instrumented Systems (known as SIS for short) are also called by other names such as Safety Shutdown Systems, Emergency Shutdown Systems (ESD) and similar terms.
Till recently, the SIS and the main plant automation systems (also known as BPCS-Basic Process Control Systems, which could be DCS or PLC based systems) used to be completely separate systems. The hardware, software and programming of both systems (BPCS and SIS) used to be totally different, like chalk and cheese. Later on, we began to see the introduction of integrated BPCS-SIS systems, where the BPCS and SIS were not totally different, but shared some of the hardware, user interface, communications network, etc. Though the programming was similar, the SIS programming was kept secure and separate with the aid of special functions in software.
Now we are seeing an even more integrated approach, in Fieldbus systems. For example FOUNDATION Fieldbus (which is one of the many Fieldbus protocols in use today) has introduced special Safety Instrumented Functions, that could be implemented in FOUNDATION Fieldbus based systems. They call this FF-SIF and this concept was presented in the FOUNDATION Fieldbus general assemby held sometime back. It is being done in a pilot project in Saudi Aramco at their Dhahran site. FOUNDATION Fieldbus recently announced that updated device development solutions for its Foundation Fieldbus for Safety Instrumented Functions (FF-SIF) technology are available. The new release includes the FF-SIF Technical Specification, Foundation for SIF Interoperability Test Kit (SIF ITK), and DD Library.
As many of you know, Fieldbus technology is rapidly gaining ground in the process industries and if the FF-SIF concept is accepted by user industries, it will lend a new meaning to the word “integrated” BPCS-SIS. In fact the distinction will get blurred. What FF-SIF proposes is to have Safety Instrumented Function blocks that will be resident in the smart devices in the field (like a humble pressure transmitter for instance) and thus can be used to implement Safety functions.This means that plants who decide to implement Fieldbus even on a smaller scale can have the power of a Safety Instrumented System, without paying a steep price for creating a separate system, programming, wiring, etc,etc. All they have to do is to utilize the SIF blocks that will presumably be available. Since the user industries main aim is to implement Safety functions in an effective manner, this seems to be a good deal for them.
If all this sounds like being too complicated, you need not worry. Simply download the Fieldbus training course from Abhisam Software that we hear is being released in Q1 of 2012 and you will be fine, fully updated and conversant with all this new technology.
