A complete externally mounted PTFE seal with exchangeable face & Non exchangeable insert for use in extremely corrosive applications such as high concentrations of acids, salts, strong oxidizing and reducing agents and chemically active organic compounds. with Hylem Flange it is used instead of SS for extremely corrosive applications such as high concentrations of acids, etc. and also with Ceramic sleeve and Ceramic stationary seat which is completely suitable for extremely corrosive applications.