A ruptured elbow in the piping associated with a hydrocracking unit air cooler released hydrocarbons and hydrogen to the atmosphere, creating a flammable vapor cloud and liquid pool. The vapor cloud migrated to an ignition source, exploded and ignited the liquid pool. The explosion and subsequent fire caused many more piping ruptures, supplying additional hydrocarbons that fed the fire.

A multidisciplinary team from Exponent analyzed the process conditions within the air cooler piping, performed a metallurgical analysis on the fractured piping, and characterized the release of flammable hydrocarbons from the original and subsequent piping ruptures. To accomplish these tasks, we reviewed process data from before and during the incident, laboratory data from samples drawn prior to the incident, process design material and heat balances, mechanical drawings for all of the vessels in the unit, photographs of the damage, and other damage assessment information.

Posted in Piping Design