PCTFE Seals
When a seal has to hold under high pressure at cryogenic temperatures, PCTFE is the fluoropolymer engineers rely on. Its rigidity, resistance to cold flow and near-zero gas permeability make it the go-to material for cryogenic valve seats and low-temperature seals, where softer polymers deform or leak. Vanéflon produces PCTFE seals, valve seats and near-net seal blanks, machined to tight tolerances and ready for the most demanding sealing applications.
You will sometimes see this material referred to by its trade names Kel-F, Neoflon or Aclon. Whichever your drawing specifies, it is the same base polymer, and Vanéflon can supply it as a seal blank, a finished seat or a fully machined part.
What is PCTFE?
PCTFE stands for polychlorotrifluoroethylene, a high-performance fluoropolymer in the same family as PTFE. The difference lies in the molecule: PCTFE replaces one fluorine atom with chlorine, which makes it harder, more rigid and far more dimensionally stable, with the lowest gas and moisture permeability of the common fluoropolymers. For a sealing material, that combination is exactly what counts.
Why PCTFE for seals
In a sealing application PCTFE brings a set of properties that few materials match:
- High rigidity and resistance to cold flow, so seats and seal rings keep their shape and their seal under sustained load and pressure.
- Excellent cryogenic performance, holding mechanical strength and elastic recovery down to extremely low temperatures.
- Outstanding gas and moisture barrier, with the lowest water vapour transmission rate of the common fluoropolymers.
- Near-zero moisture absorption, which keeps dimensions stable in humid and vacuum conditions.
- Excellent chemical resistance and non-flammability, with a high limiting oxygen index.
- Food contact compliant, meeting FDA and EU 10/2011 requirements.
Two honest points help you specify correctly. PCTFE has a higher coefficient of friction than PTFE, which makes it ideal for static seats and seal rings rather than fast dynamic seals. And while its upper temperature limit is lower than PTFE or PEEK, it is stronger and more stable in the cold, which is precisely why it dominates cryogenic sealing.
Technical specifications
- Material: PCTFE (polychlorotrifluoroethylene)
- Also known as: Kel-F, Neoflon, Aclon
- Temperature range: −273 °C to +170 °C
- Chemical resistance: Excellent
- Moisture absorption: Near-zero
- Gas permeability: Very low (lowest water vapour transmission rate of the common fluoropolymers)
- Hardness: High (rigid, low creep)
- Food contact: FDA compliant, EU 10/2011
Need the full technical detail?
Values are indicative and depend on grade. Download the complete PCTFE datasheet for full specifications, or ask our team to recommend the grade that best suits your application.
PCTFE valve seats
The single most common use for PCTFE in sealing is the valve seat. Its stability at low temperature makes it the standard choice for ball valve and butterfly valve seats in cryogenic service.
PCTFE seats stay strong, do not crack and keep sealing gases such as hydrogen, oxygen, nitrogen and natural gas, which is why they are trusted for LNG storage and transport. Their rigidity and low friction also help prevent the seat from seizing in extreme cold, a common failure point for less suitable materials.
Vanéflon machines PCTFE valve seats to your drawing, with tight and repeatable tolerances and full traceability.
Cryogenic and high-pressure sealing
PCTFE seals are at home wherever temperatures drop far below zero and pressures run high. Typical service includes liquid oxygen, liquid nitrogen and LNG handling, oxygen service, and other cryogenic and high-pressure systems in the oil and gas, aerospace and chemical industries. Because PCTFE absorbs virtually no moisture and has very low outgassing, it also performs reliably in vacuum and high-humidity environments.
Seal types in PCTFE
PCTFE is machined into a range of static sealing components:
- Valve seats for ball and butterfly valves.
- Seal rings and seat rings for cryogenic and high-pressure service.
- Back-up rings supporting elastomer or PTFE seals under high pressure.
- Gaskets for low-temperature, aggressive-media sealing.
For spring-energised seals, the jacket is more commonly PTFE, PEEK or UHMWPE, while PCTFE is chosen for the rigid seat or seal ring. If you are not sure which construction fits your operating conditions, our specialists are happy to advise.
Near-net seal blanks and semi-finished stock
Alongside finished seals, Vanéflon presses PCTFE seal blanks, seat blanks and near-net rings using compression moulding. Moulding gives uniform, ultra-low residual stress across the blank, which means tighter, more stable tolerances once machined and significantly less scrap.
With hundreds of moulds in house, we press blanks as close to final seal dimensions as possible, and we can produce our own moulds at short notice for a size we do not already hold.
Every blank comes with full traceability and certification, ready for you to finish-machine or for us to machine for you.
PCTFE compared to PEEK and PTFE for seals
Choosing a seat material is a trade-off.
- Against PEEK, PCTFE is the better choice for cryogenic seats and oxygen service, where its low-temperature stability and resistance to seizure win out, while PEEK takes over when very high pressure and high temperature dominate.
- Against PTFE, PCTFE is harder, more resistant to cold flow and holds tighter tolerances under load, which makes it the stronger sealing material at low temperature, though PTFE offers lower friction and a higher temperature ceiling.
If you are weighing up seat and seal materials, we can help you make the right call for your operating window.
Industries
PCTFE seals and valve seats from Vanéflon are trusted across:
- Oil and gas, including LNG storage and transport
- Aerospace
- Chemical processing
- Semiconductor manufacturing
- Cryogenic and industrial gas handling
Why choose Vanéflon for PCTFE seals
45+ years of expertise
High-performance plastics produced from our base in the centre of Flanders, Belgium, with deep experience in liners, coated discs, valve seats and chevron seals.
A design partner, not just a supplier
Customers rely on us for material selection as much as for reliable, flexible delivery.
From powder to final product
Full in-house know-how, with every order traceable and certified.
Reliable supply, made to your drawing
Flexible VMI systems and everything from near-net seal blanks to finished PCTFE valve seats machined to spec.
Frequently asked questions
Request a quote
Looking for a reliable partner for PCTFE seals and valve seats? Vanéflon supports you from material choice through to the finishing of the most complex sealing components.
Request a quote or reach out to our team, and we will come back with the right solution, tolerances and lead time.
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