What is PTFE?
Discovered by accident in 1938 by American chemist Dr Roy J. Plunkett in the DuPont™ laboratory, Polytetrafluoroethylene (PTFE) is a thermoplastic polymer with a linear chain of carbon atoms, surrounded by fluorine atoms. High performing as a virgin material, PTFE can also be filled with many other elements to bolster its appeal and usage.
Ceetak’s expert team of engineers work with customers to ensure the right material is selected for the needs of each valve application, let’s explore more about the chance discovery of PTFE and its benefits.
Why choose PTFE for your valve applications?
Due to its versatility, PTFE is widely used in sealing applications for valves in industries with high usage and demands.
Its unique ability to withstand contact with virtually all known chemicals (only a few media are known to react with PTFE), and its composition and properties, give PTFE a thermal stability and excellent high to low temperature rating. The high melting point (342 °C) and structural characteristics allow seals (virgin PTFE) to be constantly used at temperatures of up to 260 °C. In contrast, PTFE seals can withstand cryogenic temperatures and aggressive chemicals such as liquid nitrogen and liquid helium.
Thanks to this unintentional innovation nearly 100 years ago, industries including oil & gas, petrochemical, and CPI can benefit from the qualities of valves fitted with PTFE sealing systems, seats, and linings. A great choice due to its resistance to harsh environments and extremely corrosive chemicals including cleaning and sterilisation fluids, and its inherent biocompatibility makes it safe for food & beverage, water and pharmaceutical applications. Many grades carry well known institutional approvals relevant to individual markets, including FDA, USP, UL and NORSOK standards.
PTFE seals: Benefits and considerations
Benefiting from an unlimited shelf life, PTFE is a synthetic self-lubricating polymer offering continuous dry running capabilities in dynamic sealing applications. Additional lubrication is infrequently required because in some cases, the use of a lubricant can introduce hard wear particles to the seal interface. Dry assembly of PTFE seals is commonly recommended to avoid this risk.
Despite the existing advantages of virgin PTFE, its qualities are amplified by the addition of fillers to strengthen and improve its physical properties such as creep and wear rate. Fillers include glass, carbon, bronze, and graphite. Although the cost of PTFE is generally higher than elastomer moulded seals, PTFE is moulded into cylindrical billets and machined to manufacture seals; this is advantageous to customers to produce lower volume prototypes and allows rapid lead times.
Working with Ceetak: the right material for your valve application?
Here at Ceetak, we understand the challenges, technical demands and the need for long service life and minimal maintenance needed for valve application sealing. Our extensive expertise means we can quickly identify and specify the optimal seal solution. We have recently worked with a customer who was using elastomer seals on the stem of a quarter turn valve which was failing due to operation at low temperatures after long periods of inactivity. We worked with this customer to replace the seals with a low friction PTFE seal, this solved the stick-slip problem, and the customer is satisfied their application is now working to its maximum performance.
Our range of PTFE seal products include back-up rings, rod and piston seals, slipper seals and spring energised seals in a wide variety of sizes and can be virgin or filled PTFE.
For more information about how Ceetak’s products and services can benefit your organisation, visit www.ceetak.com, or to speak to one of our expert team, phone +44 (0)1234 832200.
Telephone: +44 (0)1234 832200