A case study of a TFE explosion in a PTFE manufacturing facility



A 1999 explosion in the purification area of a fluorinated polymer manufacturing plant in the United States caused fatal injuries to three employees. Another employee was severely injured. The affected plant personnel were attempting to locate a suspected polymer plug in lines containing tetrafluoroethylene (TFE) monomer upstream of the polymerization plant. In an attempt to dislodge a possible plug in an elbow leading off a pressure vessel, one of the employees rapidly actuated a manually operated ball valve. High-pressure TFE upstream of the valve rushed into the downstream piping, which likely contained air at subatmospheric pressure. Adiabatic compression against a blind flange created temperatures sufficient to ignite a TFE/air mixture. The initial deflagration provided ample energy for a self-sustaining decomposition reaction to propagate within the TFE line into the upstream pressure vessel. Liquid TFE had been collecting in the pressure vessel as the result of a deliberate increase in the flow of cooling brine associated with a separate process. This allowed the decomposition to continue, causing a rapid increase in pressure inside the vessel, sufficient for the bolts on the upper flange to fail. The four employees were exposed to burning TFE sprayed from the pressure vessel and were also injured by shrapnel created by the explosion.

Exponent Failure Analysis Associates was retained to conduct an engineering investigation of the incident, including a technical analysis of the conditions leading to the explosion. We also reviewed the HAZOP performed by the employer that failed to note critical parameters that contributed to the incident. This article discusses findings from the investigation as well as lessons on handling TFE that can be learned from the incident. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2007