Polytetrafluoroethylene (PTFE) is almost chemically inert being attacked only under extreme conditions by molten
alkali metals, certain fluorine compounds at elevated temperature and nuclear radiation. In this respect PTFE is very
useful as a gasket material, but unfortunately, the material has a tendency to creep under load and has limited use in
Modified PTFE materialsallow the benefits of PTFE to be utilized at higher compressive loads and higher temperatures. Expanding the PTFE, for example, produces a softer material with a higher strength than conventional PTFE. Whereas the addition of a filler such as silica, silicon carbide or barium sulphate lends the material better hot and cold flow resistance without negatively affecting the chemical resistance.
PTFE can also be used as an envelope to a more conventional compressed fibre gasket material insert. This combines the chemical resistance of the PTFE with the stress retention and recovery properties of the insert and reduces the negative effect of the PTFE on the joint’s mechanical stability.
General Properties of PTFE
Outstanding chemical resistance
Suitable for use with foodstuff and pharmaceutical applications
Insoluble in solvents, even at increased temperature
Stable to light
Does not absorb water
Excellent electrical insulating capacity
Low thermal conductivity
Expanded PTFE materials has good creep resistance and bolt torque retention properties allowing it to be used to
higher temperatures and to seal higherinternal pressures.
Expanded PTFE tape form with a pressure sensitive adhesive backing strip to assist with installation. Since the material is available in roll form it offers asolution to jointing needs without the need to maintain large stocksof cut gaskets.
Good mechanical properties at low to medium temperatures
Excellent chemical resistance
Available in sheet form and as cut gaskets
PTFE Envelope with compressed fiber insert
Excellent chemical resistance.
PTFE envelope gaskets comprise a compressed synthetic fibre gasket material insert with a PTFE envelope. The PTF Eenvelope protects thegasket from chemical attack. The insert provides the strength and resilience needed for demanding sealing operation.
This gasket offers excellent chemical resistance under moderate conditions of temperature and pressure.