A PTFE envelope gasket is a composed gasket. The product consists of an envelope of PTFE with an inlay. The envelope gasket is mainly applied as a flange gasket in applications where a high chemical and high pressure resistance is required.

PTFE envelope gaskets are used in equipment handling chemicals and petrochemicals because they are resistant to corrosive fluids and extreme temperature extremes. Except for certain alkali metals and fluorine compounds, PTFE demonstrate resistance to most chemicals at various pressures and temperatures.