Lessons learned from a supercritical pressure BLEVE in Nihon Dempa Kogyo Crystal Inc.

• Demonstrated that cracking on the vessel compromised its capability of holding high pressure.
• Identified the incident as a supercritical pressure Boiling Liquid Expanding Vapor Explosion (BLEVE).
• Evaluated the accuracy of several BLEVE overpressure estimating models by comparing with investigation observations.
• Compared several blast fragment models with investigation observations.
• Recommended to improve the overall safety culture.

On December 7, 2009, a 50-foot-tall high-pressure vessel ruptured in the Nihon Dempa Kogyo Crystal, Inc. facility in Belvidere, Illinois. Several projectiles rapidly traveled outward from the facility, killing a truck driver 650 feet away and injuring an employee in another building 435 feet away. This paper summarizes the lessons learned from this incident both on causal and consequential aspects. Stress corrosion cracking was identified as the failure mechanism by the U.S. Chemical Safety and Hazard Investigation Board. After analyzing the operating conditions and the aftermath, this incident has been identified as a Boiling Liquid Expanding Vapor Explosion (BLEVE) under a supercritical pressure. A consequence analysis of the incident is performed where overpressure and fragment distance are calculated, together with safety distance estimation. Additionally, other safety-related problems, such as safety culture, management inside the corporation, and communication between this facility and the government are discussed.