On the morning of August 14, 2002, 48,000 pounds of chlorine was released over a 3-hour period during a railroad tank car unloading operation at DPC Enterprises, L.P., near Festus, Missouri. The facility repackages bulk dry liquid chlorine into 1-ton containers and 150-pound cylinders for commercial, industrial, and municipal use in the St. Louis metropolitan area.

Chlorine is a toxic chemical. Concentrations as low as 10 parts per million are classified as “immediately dangerous to life or health” (NIOSH, 2003). Although the wind direction on the day of the release carried the majority of the chlorine plume away from neighboring residential areas, some areas were evacuated. Sixty-three people from the surrounding community sought medical evaluation at the local hospital for respiratory distress, and three were admitted for overnight observation. The release affected hundreds of other nearby residents and employees, and the community was advised to shelter-in-place for 4 hours. Traffic was halted on Interstate 55 for 1.5 hours. Three DPC workers received minor skin exposure to chlorine during cleanup activities.

This incident began with the failure of a chlorine transfer hose (CTH) connecting a tank car to the facility repackaging process. The U.S. Chemical Safety and Hazard Investigation Board (CSB) determined that the ruptured hose was constructed of stainless-steel braid rather than Hastelloy C, a metal alloy (CSB, 2002).

KEY ISSUES:
• MECHANICAL INTEGRITY
• EMERGENCY MANAGEMENT
• CHLORINE TRANSFER HOSE SUPPLY

ROOT CAUSES:
1. The DPC quality assurance (QA) management system did not have adequate provisions to ensure that chlorine transfer hoses met required specifications prior to installation and use.
2. Branham Corporation, the CTH fabricator/distributor, did not have a QA management system to ensure that fabricated hose complied with customer specifications or that its own certification of materials specifications were correct.
3. The DPC testing and inspection program did not include procedures to ensure that the process emergency shutdown system would operate as designed.

Image Credit: CSB