PTFE is mainly used for its highly remarkable chemical resistance, both in the food and pharmaceutical industries. The usage of this material at high scale is though limited due to its predisposition to dilatation. Sintered or expanded PTFE is used for many applications that require sealing. Nowadays, the majority of sintered PTFE is being replaced by the so-called by-axial or stabilized PTFE.
Important characteristics in the sealing sector:
- Chemical resistance in almost every chemical environment, except melted alkaline metals and high temperature fluorine products
- Very low friction coefficient
- Chemically inert
- Very good thermic stability between -200ºC … +250º C
- Can be mixed with several elements for properties improvement (e.g.: glass, ceramics, carbon/graphite, bronze etc – for the increase in ageing, dilatation factor etc)
A wide variety of filling material is being used in order to ensure additional properties, but these have to be evaluated individually so as to not affect the compatibility with the working fluid and the hygienic requirements. The usual filling materials used are glass, graphite, bronze, silicon, barite and limestone flux.
- Fluids: all fluids
- Temperature: -200 up to 250°C
- Pressure: 60 bar (PTFE sintered), 30 bar ( PTFE expanded)