POLYTETRAFLUOROETHYLENE (PTFE)
PTFE is used as a filler material in Flexitallic gaskets where extreme chemical inertness is required. PTFE is unaffected by any known
chemicals except molten alkali metals and fluorine precursors. Because of its low permeability, PTFE is also frequently used as a filler
material on FLEXITALLIC gaskets in vacuum applications. Gaskets wound with PTFE should be fully confined either by fitting in a
groove or providing both an external and internal ring.