Meaning
Chemical or physical breakdown of polytetrafluoroethylene caused by extreme temperature and ionizing radiation. While generally inert, ptfe degradation leads to a loss of tensile strength and increased porosity. It limits the service life of valve seats and gaskets in harsh chemical environments.
Thermal Resistance
Exceeding the continuous service temperature of 260 degrees Celsius triggers the liberation of toxic hydrogen fluoride. This process of ptfe degradation results in the softening of the polymer and a subsequent loss of sealing pressure. Heat induced failures typically appear as distorted or extruded seal rings that no longer contact the metal surfaces correctly.
Radiation Exposure
Nuclear power and medical sterilization facilities subject materials to high energy gamma rays that sever the carbon fluorine bonds. When ptfe degradation occurs in these settings, the material becomes brittle and prone to cracking under vibration. Designers select alternative fluoropolymers or metallic seals when the cumulative dose exceeds ten kilograys.
Replacement Schedule
Preventive maintenance intervals for chemical processors depend on the predicted rate of material wear. Because ptfe degradation is irreversible, the components must be replaced before the leak rate exceeds the allowable limit defined in the piping class. Detailed logs of operating hours at peak temperatures allow managers to forecast parts procurement and labor requirements.
