Stainless Steel Plug Valve Incident in High Pressure Oxygen: Delrin (R) Seat and Silicone-Based Lubricant

A fire occurred in a stainless steel plug valve after completing a high pressure oxygen filling operation. The incident plug valve was being used to manually limit pressurization rates to downstream oxygen cylinders up to 20.7 MPa (3,000 psi). Fire developed within the plug valve when the filling operation was being completed (valve closing) and proceeded to burn out a downstream flexhose. Following the incident, it was determined that the plug valve had a Delrin (R) (acetal) seat and silicone-based lubrication. An insightful observation from the incident was that the relatively large Delrin seat combined with the silicone-based lubrication did not kindle the stainless steel body or valve plug. This paper describes the incident and provides a summary of observations and discussion regarding this oxygen fire.