US CSB cites human error in Formosa vinyls explosion

Houston (Platts)--6Mar2007

The US Chemical Safety Board Tuesday issued its final report on the
explosion and fire that destroyed the Formosa Plastics plant in Illiopolis,
Illinois, on April 23, 2004, concluding that the accident occurred when an
operator overrode a critical valve safety interlock on a pressurized vessel
making polyvinyl chloride.

As a result, vinyl chloride liquid and vapor discharged into the plant
and was ignited resulting in a massive explosion. The CSB found 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 PVC reactor. The
investigation further determined that the measures both companies
took were insufficient to prevent human error or minimize its consequences.

The accident resulted in the deaths of five workers and serious injuries
to three others. The facility was heavily damaged and has been permanently
closed.

A 1992 Borden hazard analysis recommended safeguards which were never
adopted. Later, in 1999, another Borden analysis again identified the same
potential consequences -- a massive release of vinyl chloride -- but
determined that the existing safety interlock was sufficient to prevent a
serious accident.

In 2003, an operator at the Formosa plant in Baton Rouge, Louisiana,
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 but the company determined changes were not needed in Illiopolis because
the valve controls were different.

In February 2004, 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, the company did not act quickly enough. The
fatal explosion occurred just two months later.