The Map Ta Phut petrochemical hub, in Rayong province is one of the larger industrial parks in Asia, having petrochemical and other hydrocarbon processing plants of several companies. The present accident occurred in the BST plant that produces various kinds of synthetic rubber including BR (Butadiene Rubber) and SBR (Styrene Butadiene Rubber).

The incident apparently occured as a storage tank was being flushed using Toulene, a solvent to remove material before a product changeover operation. It is not clear how the tank caught fire, nor the root cause of the explosion. Initial estimates of damage are in the region of  about Bt 1.7 billion (Thai Baht 1.7 billion) according to unconfirmed news reports. Officials from the Map ta Phut industrial park said that the ambient air was being monitored for contaminants and carcinogens and upto now, the levels were not alarming. Toluene is not carcinogenic although the vapors in sufficient concentration can cause eye and skin irritation. Locals who stay in the vicinity were concerned about the after effects.

Meanwhile, reports say that the Prime Minister of Thailand, Ms.Yingluck Shinawatra herself and other  top govt officials summoned a meeting , where the seniormost management of BST was present, apparently to carry out mitigation efforts and investigate the cause of the disaster. A tri-partie committee has been formed to inspect the site. Damage at the BST site, as well as at the adjoining facilities will be inspected. A review of the laws governing industrial facilities, disaster and emergency preparedness and other areas is also being proposed apparently as a result of the accident.

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.

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.”

A series of preventable safety shortcomings — including failure to maintain the mechanical integrity of a critical phosgene hose — led to a string of three serious accidents that occurred over a 33-hour period on January 22 and 23, 2010, at the DuPont Corporation’s Belle, West Virginia, chemical manufacturing plant, according to the draft report of the U.S. Chemical Safety Board (CSB) which was issued today. In one of the accidents, a worker died following exposure to phosgene, a gas used as a chemical weapon in World War I.

The report makes numerous safety recommendations. Among them, DuPont is urged to enclose all of its phosgene production and storage areas so that any releases of phosgene will be contained. The CSB recommends that the Occupational Safety and Health Administration (OSHA) update its compressed gas safety standard to include secondary enclosures for toxic gases such as phosgene.

 The draft report and recommendations remain subject to change and final approval by a vote of the presidentially-appointed board of the CSB.  That vote is expected to occur following a 45-day comment period which closes on August 22.

DuPont’s Belle facility occupies more than 700 acres along the Kanawha River, eight miles east of Charleston, the state capital.  The plant produces a variety of specialty chemicals.

The series of accidents began on January 22, 2010, when an alarm sounded leading operators to discover that 2,000 pounds of methyl chloride, a flammable gas, had been leaking unnoticed into the atmosphere for five days.  The next morning, workers discovered a leak in a pipe carrying oleum, producing a fuming cloud of the sulfur trioxide.  The phosgene release occurred later that day, and the exposed worker died the next day in a hospital.  
CSB Chairman Rafael Moure-Eraso said the three accidents particularly concerned CSB personnel given DuPont’s longstanding reputation for a commitment to safety.  Noting the company started as a gunpowder manufacturer in 1802, and became a major chemical producer within 100 years, Dr. Moure-Eraso said, “DuPont has had a stated focus on accident prevention since its early days. Over the years, DuPont management worked to drive the injury rate down to zero through improved safety practices.”

Dr. Moure-Eraso continued, “DuPont became recognized across industry as a safety innovator and leader. We at the CSB were therefore quite surprised and alarmed to learn that DuPont had not just one but three accidents that occurred over a 33-hour period in January 2010. 

CSB board member and former chairman John Bresland also spoke at the news conference:  “These kinds of findings would cause us great concern in any chemical plant – but particularly in DuPont with its historically strong work and safety culture. In light of this, I would hope that DuPont officials are examining the safety culture company-wide.”   

Member Bresland noted the CSB finding that the phosgene hose that burst in front of a worker was supposed to be changed out at least once a month.  But the hose that failed had been in service for seven months. Furthermore, the CSB found the type of hose involved in the accident was susceptible to corrosion from phosgene.

Team Lead Johnnie Banks said, “Documents obtained during the CSB investigation showed that as far back as 1987 DuPont officials realized the hazards of using the braided stainless steel hoses lined with Teflon, or PTFE. An expert employed at DuPont recommended the use of hoses lined with Monel, a strong metal alloy used in highly corrosive conditions.  The DuPont official stated: ‘Admittedly, the Monel hose will cost more than its stainless counterpart. However, with proper construction and design so that stresses are minimized…useful life should be much greater than 3 months. Costs will be less in the long run and safety will also be improved.’”

In fact, the Monel hose was never used.

Internal DuPont documents released with the CSB draft report indicate that in the 1980’s, company officials  considered increasing the safety of the area of the plant where phosgene is handled by enclosing the area and venting the enclosure through  a scrubber system to destroy any toxic phosgene gas before it entered the atmosphere. However, the documents show the company calculated the benefit ratio of potential lives saved compared to the cost and decided not to make the safety improvements. A DuPont employee  wrote in 1988,  “It may be that in the present circumstances the business can afford $2 million for an enclosure; however, in the long run can we afford to take such action which has such a small impact on safety and yet sets a precedent for all highly toxic material activities?”

The need for an enclosure was reiterated in a 2004 process hazard analysis conducted by DuPont, but four extensions were granted by DuPont management between 2004 and 2009, and at the time of the January 2010 release, no safety enclosure or scrubber system had been constructed.   CSB investigators concluded that an enclosure, scrubber system, and routine requirement for protective breathing equipment before personnel entered the enclosure would have prevented any personnel exposures or injuries.

The CSB investigation found common deficiencies in DuPont Belle plant management systems springing from all three accidents:  Maintenance and inspections, alarm recognition and management, accident investigation, emergency response and communications, and hazard recognition.

CSB Team Lead Banks said, “The CSB found that each incident was preceded by an event or multiple events that triggered internal incident investigations by DuPont, which then issued recommendations and corrective actions. But this activity was not sufficient to prevent the accidents from recurring.”

The CSB draft report recommends that the DuPont Belle facility revise its near-miss reporting and investigation policy to emphasize anonymous participation by all employees so that minor problems can be addressed before they become serious. The CSB report also recommends the Belle plant ensure that its computer systems will provide effective scheduling of preventive maintenance to require, for example, that phosgene hoses get replaced on time.
 
The CSB draft recommends that the DuPont Corporation require all phosgene production and storage areas company-wide have secondary enclosures, mechanical ventilation systems, emergency phosgene scrubbers, and automated audible alarms, which are at a minimum consistent with the standards of the National Fire Protection Code 55 for highly toxic gases.

 Industry groups have established various good practices for the safe handling of phosgene and other highly toxic materials in compressed gas cylinders.  The draft report concluded that the most comprehensive guidelines are those set forth by the National Fire Protection Association, or NFPA. 
 
The draft report recommends that industry-organizations such as the Compressed Gas Association (CGA) and the American Chemistry Council (ACC) adopt the more stringent guidelines of the NFPA for the safe handling of phosgene and other highly toxic gases.  

The report recommends the Occupational Safety and Health Administration (OSHA) update its compressed gas safety standard to include modern safeguards for toxic gases such as phosgene.  These improved safeguards include: Secondary enclosures for units using phosgene, mechanical ventilation systems, emergency phosgene scrubbers, and automated audible alarms. 

Chairman Moure-Eraso said, “Adoption of the CSB recommendations by OSHA,  the Compressed Gas Association and the American Chemistry Council and, would greatly increase the safe handling of toxic gases  nationally, and will protect  workers from the deadly exposures.” 
 
     Dr. Moure-Eraso noted that he welcomes today’s release of the draft report and invites public comment on it.  “Comments concerning the draft report will be carefully considered following the public comment period, after which Board Members will vote on the findings and recommendations.  The report is not final until the vote is taken.”

The video is entitled “Fire in the Valley,” a reference to the Kanawha River valley where numerous chemical facilities are located, including the Bayer plant that manufactures insecticides, near Charleston, West Virginia.
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The video features a detailed computer animation showing how a series of errors and deficiencies during a lengthy startup process resulted in a runaway chemical reaction inside a residue treater pressure vessel. The CSB’s investigation found that operators were not adequately trained, new computer process equipment had not been fully checked out, and a critical safety interlock was bypassed to begin a chemical reaction.

Investigations Supervisor John Vorderbrueggen, P.E. discusses the CSB’s findings, “We found serious deficiencies in the company’s process safety management program. This resulted in a series of critical omissions during the startup that led to a runaway reaction and violent explosion.”
These events contributed to the over pressurization of the residue treater which ultimately exploded and careened into the methomyl pesticide manufacturing unit, leaving a huge fireball in its wake.  Pieces of the vessel struck a steel-mesh covering surrounding a large tank of methyl isocyanate, a highly toxic chemical of concern to residents of the valley since 1984 when an accidental release of MIC in Bhopal, India, killed thousands.
In the video, CSB Chairperson Rafael Moure-Eraso says, “The communities surrounding Bayer CropScience have been concerned for decades about the MIC stored there.  Its presence added even more gravity to the series of safety lapses the CSB investigation found to have preceded the tragedy.   And when the accident occurred, the company refused to give out critical information to responders and the public.”
Ultimately, 40,000 area residents were requested to shelter-in-place the night of the accident. The video features comments by county and state officials on the initial refusal of Bayer to provide information to Metro 911 emergency response operators as well as resident’s concerns about chemical plant safety in the area. “Fire in the Valley” also details the key CSB safety recommendation that Kanawha Valley county authorities emulate the regulatory regime of Contra Costa County, California. There, chemical process safety experts regularly inspect the multitude of facilities throughout the county in a program that is paid for by a proportional levy on the plants. The program’s director, Randy Sawyer, comments in the CSB video on the success of the program.
Chairperson Moure-Eraso concludes the video saying, “Good communications between chemical plants, responders, and community leaders can help assure the safety of workers and residents during an emergency. But preventing accidents requires companies to have effective process safety management programs. The fact that accidents continue to occur shows the need for improved inspections and oversight whether at the federal or local levels.”