The envelope gaskets are well suited for use in applications where the integrity of pure PTFE and the good mechanical properties of the gasket material inside the casing are to be combined.
Typical use cases are glass and reinforced plastic pipes in the pharmaceutical, chemistry and food industry.
Inside the envelope gaskets, in a PTFE shell, is a soft fiber seal. Depending on the application, the envelope gaskets can also be manufactured in many millimeters in thickness. Then, inside the shell are many soft rubber or fiber seals, and in between them, a corrugated metal plate.
There are several variations of the shell types, for example, fin and square types. Most often, we use a square-type envelope because the flow of the medium remains unchanged. The inner surface of the square type envelope has a deep PTFE area, which assures the soft seal within the interior to remain untouched despite minor interior damage.