CSB: Human Error Caused Formosa Blast

March 7, 2007
A report issued by the Chemical Safety and Hazard Investigation Board (CSB) concludes that human error was the cause of a 2004 explosion that killed five workers and seriously injured three others at a Formosa Plastics chemical plant in Illiopolis, Ill.

According to CSB, the blast occurred when a Formosa operator mistakenly opened a valve while a pressurized vessel was making polyvinyl chloride. CSB determined that both Formosa and Borden Chemical – the company from which Formosa purchased the plant in 2002 – were aware of the possibility of serious consequences of an inadvertent release of chemicals from an operating reactor but took insufficient steps to prevent human error.

CSB Chairman Carolyn Merritt said that companies should regularly train for emergency situations.

“People do make mistakes,” Merritt said. “And that is why it is all the more important for chemical plants to design systems that take into account the possibility of such errors. This accident occurred because the companies involved did not look closely enough at the potential for catastrophic consequences resulting from human error.”

Formosa spokesman Rob Thibault said that the company completed an internal investigation about a year after the 2004 explosion. He added that Formosa has “already started or completed many of the recommendations the Chemical Safety Board has recommended.”

CSB: Evacuation Training Might Have Saved Lives

After interviewing survivors and examining physical evidences, CSB surmised that the operator became confused about which of the plant's reactors he was cleaning. When he opened up the valve on the reactor that was in operation, according to CSB, he neglected to ask someone why the valve wasn't opening and instead attached an air hose to override a safety interlock. As a result, vinyl chloride sprayed onto the floor and vapor filled the room, prompting the explosion.

The operator and four others perished in the blast.

According to CSB, the operators had time to evacuate the building after the release but chose to remain in the area in a vain attempt to mitigate the release.

CSB lead investigator Lisa Long said that in addition to not implementing steps to minimize potential for human error, Formosa did not “adequately train and drill its employees to immediately evacuate in case of a major release of hazardous chemicals.”

“Such an evacuation would have saved lives,” she said.

The report suggests that safeguards such as locks or other devices to secure the interlock system could have prevented critical valves from being opened when the reactor was pressurized.
Investigators also noted that the reactors were grouped into similar sets of four, increasing the possibility of human error. Yet, according to CSB, there were no gauges, indicators or warning lights to inform operators on the lower level of a reactor's operating status. Operators on the lower level, where the valves were, did not carry radios or have intercoms to communicate with the upper level panel operators.

CSB: Formosa Dealt with Same Issue Before

CSB noted that Formosa has dealt with the same issue before. In 2003, an operator at the Formosa plant in Baton Rouge, La., opened the bottom valve on the wrong reactor, releasing 8,000 pounds of vinyl chloride into the atmosphere. Some safety improvements were made in Baton Rouge, according to CSB, but the company determined changes were not needed in Illiopolis because the valve controls were different.

In February 2004, according to CSB, an operator at the Illiopolis plant bypassed a bottom valve safety interlock, releasing a significant amount of vinyl chloride. After that incident, the company determined that additional controls were needed on the interlock. However, CSB asserted, the company did not act quickly enough. The fatal explosion occurred just 2 months later.

CSB Recommendations

CSB is recommending that Formosa review the design and operation of all of its U.S. PVC facilities. CSB also is urging Formosa to:

  • Ensure chemical processes are designed to minimize the consequences of human error.
    Improve control of safety interlocks.
  • More thoroughly investigate high-risk hazards.
  • Consider all consequences in near-miss investigations.
    Improve emergency planning and conduct periodic drills, emphasizing prompt evacuations.

In addition to the final report, CSB released a safety video that details key findings and recommendations and contains a computerized animation of the likely scenario of events leading to the explosion. The video will be available late in the week of March 5 on CSB's Web site.

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