(32bg) Formosa Plastics Vinyl Chloride Explosion

On April 23^rd, 2004, a catastrophic release, explosion, and fire occurred at the Formosa Plastic Corporation polyvinyl chloride production plant in Illiopolis, Illinois (Formosa-IL), killing five workers and severely injuring three others. The explosion destroyed much of the plant area and day-shift offices of the plant, while the resulting fire ignited polyvinyl chloride (PVC) resins in an adjacent warehouse, covering the surrounding community in a thick cloud of acrid smoke. As a result, the households within a mile radius of the facility were evacuated, and after extensive testing, little to no hazardous materials were present in the surrounding environment. The facility was completely destroyed and did not reopen.

The explosion was caused by the total release of a reacting mixture of flammable, highly hazardous vinyl chloride monomer (VCM) from the bottom of a reaction vessel, creating a flammable vapor cloud that soon detonated. The Chemical Safety Board (CSB) later found that an operator had inadvertently opened the reacting vessel by manually overriding a safety bypass without supervisor permission. The operator had mistaken the reacting vessel for one that he had been cleaning.

Upon investigation of the root causes of the incident, the CSB identified the presence of a single procedural safeguard to prevent a catastrophic release as the main cause of the fatal incident. The bypass of the pressure safety valve relied only on verbal permission from a supervisor, which was not obtained. The risks of such a system were largely ignored by Formosa Plastics despite previous release events at another plant as well as the destroyed plant. Furthermore, it was found that the previous operator of the plant, Borden Chemical, failed to implement findings of severe consequences for opening the safety interlock in a process hazard analysis, and Formosa Plastics failed to complete a thorough hazard and safety analysis upon acquiring the plant. Formosa-IL’s reliance on written procedures for a hazard with potentially deadly consequences stood in clear contrast with the Process Safety Management guidelines set for by the AIChE’s Center for Chemical Process Safety (CCPS), indicating a lack of sufficient layers of protection.

In response to this incident, the Chemical Safety Board issued a variety of recommendations to Formosa Plastics as well as relevant regulatory bodies. Primarily, they called for a company-wide, continuous audit of Formosa’s United States vinyl chloride plants to establish procedures and authorization levels for bypassing safeguards, implementing a safety philosophy to minimize risk of catastrophic incidents, promptly correcting risks found in hazard analysis and near misses, the implementation of layers of protection analysis, and a complete rework of emergency response protocols and training. The members of the board called upon the NFPA to edit its standard regarding water deluge systems for mitigating flammable vapor releases, and they also directed the EPA to consider the lessons learned from this incident in its future investigations. Finally, the CSB directed the Vinyl Institute to distribute a warning about the incident to its member corporations, and it recommended that the CCPS release guidelines regarding safety analysis after the acquisition of facilities from other companies.

The CSB’s recommendations were far-reaching and more than sufficient to prevent vinyl chloride plant releases and explosions in the future.