(73c) Tracing Source of Ethylene Oxide Gas House Explosion Using Damage Indicators and Thermal Modeling

An explosion destroyed a small ?Gas House? in which aerosol cans were being filled with ethylene oxide on June 24, 1997. At issue was whether the ignition occurred in the Gas House or from a remote catalytic converter. Our investigation of the pattern of blast damage supports ignition at the catalytic converter that generated a burn-back through the ducting. A strong jet ignition reached a flammable atmosphere in the Gas House and ignited an explosion that well exceeded the yield strength of the prefabricated metal Gas House in spite of the vent panels and access doors being released and discharging of the fire suppression system. One of the doors from the Gas House flew off of the building as hazardous debris, which impacted and catastrophically failed a second door located in an adjoining occupied building. This resulted in the only fatality associated with this event.

This paper illustrates the damage patterns that indicate the direction of the initial explosion wave. These damage indicators included the thin plates on a heat exchanger that were distorted in a distinct pattern, debris that was lodged in the heater coils, plenum chamber panels that were distorted and ruptured, and the end-caps from a 24-inch header that were also distorted and ruptured. This and other steel component distortion patterns were pieced together and in some instances modeled to infer the magnitude of the explosion and its direction. The catalytic converter exhibited a color pattern in the sheet metal, indicative of heat damage. Modeling of this converter established that the temperatures generated from combustible gas concentrations in the flammable range were consistent with the metal color patterns.