PTFE Based Gaskets

PTFE -based gasket materials are able to withstand significantly more aggressive chemical environments (including highly oxidizing environments) than standard non-asbestos gasket materials. However their temperature, pressure and mechanical performance is inferior to standard non-asbestos gasket materials. Metal inserted and expanded PTFE are able to operate at higher pressures. 

Mercer carries Garlock, Thermoseal and Gore-Tex brands of PTFE -based gasket materials. These materials are available in thicknesses 1/32" through 1/4".

Material Max T 
Max P 
Creep Rel'n 
Pure PTFE 450 800 35 - 55 Excellent chemical resistance.
Filled PTFE 450 1200 11 - 40 Excellent chemical resistance.
Filled PTFE - Metal Inserted 450 2500 20 Excellent chemical resistance. 316 SS perforated core.
Expanded PTFE 450 3000 30 Excellent chemical resistance. Highly compressible.

PTFE® -based gaskets
There are three basic types of PTFE® gasket materials. Virgin PTFE® , filled PTFE® and expanded PTFE® .

PTFE is principally used as a gasket material because of it's capability to remain unaffected by the majority of chemicals used in industry. It is also classified, in most cases, as a food grade material, making it acceptable to both medical and food production industries. There are three basic types of PTFE gasket materials. Virgin PTFE , filled PTFE and expanded PTFE .

Virgin PTFE is by far the least expensive of the three varieties, and is used in most general applications. Filled PTFE is a gasket material with a virgin PTFE base to which a substance is added during manufacture to improve the sealing characteristics of PTFE . This "filler" usually is glass or graphite particles although ceramics has sometimes been used. The resulting gasket material is strong, yet highly compressible with very good, though not universal, chemical resistance.

Expanded PTFE is virgin PTFE to which a stress resistance has been added by means of molecular rearrangement during manufacture. This process ensures that the molecular chains from which the PTFE is constructed, do not arrange themselves into set patterns. This means that expanded PTFE possesses no structural weakness (grain) and expands and contracts equally in all directions. Because no additives are required, expanded PTFE also possesses the unique chemical resistance of virgin PTFE .

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