Drake CryoDyn®™ CT-200 stock shapes have been developed to provide a higher performance alternative to PCTFE for machined seals and related components that must operate reliably at cryogenic temperatures.
PCTFE, a fluoropolymer material, was Initially available under 3M’s discontinued Kel-F® brand and has been used as a material for seals for many years. It now carries the Neoflon® PCTFE trade name and is manufactured in Asia. PCTFE supply issues created the need for an alternative with no compromise in performance.
Drake extrudes CryoDyn® CT-200 stock shapes from Victrex CT™-200 resin in a range of sizes. The specially formulated polyaryletherketone-based polymer provides an upgrade to PCTFE in properties important to effective sealing in cryogenic applications. It also performs effectively in seals used at temperatures up to +302°F (+150°C) and beyond, where polyaryletherketones have a long history of proven performance.
Processing conditions are a key factor in achieving the CT-200 resin’s full performance capabilities in extruded stock shape form. Based on physical properties testing, Drake CryoDyn® CT-200 stock shape properties are directly comparable to Victrex’s CT-200 data sheet values. Because of this parity, Drake uses the Victrex grade designation as part of our CryoDyn® CT-200 brand, and customers can count on stock shapes with the performance they expect from this advanced polymer in every shipment they receive.
CryoDyn® CT-200 Performance
Victrex CT-200 resin used to produce CryoDyn® CT-200 shapes is specially formulated for improved bearing and wear properties. CryoDyn® CT-200 has a lower coefficient of friction than PCTFE, which can translate to lower actuation torque in properly designed components machined from CryoDyn® CT-200. Its wear resistance also affords longer service life for cryogenic ball seat valves and similar applications based on laboratory tests of CT-200 resin conducted at -321°F (-196°C).
For sealing integrity in any end-use environment, machined applications must maintain their dimensional stability over wide temperature swings. Two factors play significant roles: The CT-200 polymer’s inherently lower coefficient of expansion compared to PCTFE, and Drake’s technology for extruding stock shapes with minimal internal stress levels. High residual stresses can result in distortion in machined parts when exposed to temperature fluctuations, and also make it difficult to machine seals with the consistent precision tolerances they require.
Drake CryoDyn® CT-200 typically exhibits twice the mechanical strength of PCTFE. Its ability to maintain higher strength over a wide temperature range is a key asset in maintaining seal integrity. It also has the level of ductility necessary to replace PCTFE in seals based on testing from -321°F (-196°C) to +302°F (+150°C).
Design engineering note: PCTFE has a much higher elongation than CryoDyn® CT-200. As a result, some component design differences such as thinner sealing sections should be expected with CryoDyn® CT-200 as a PCTFE alternative for parts to function properly given CT-200’s higher strength and lower elongation.
Mechanical properties testing on CryoDyn® CT-200 shows that it has greater creep resistance than PCTFE, an advantage in maintaining sealing effectiveness longer under high loads especially as temperatures increase.
Thermal conductivity is another performance factor where CryoDyn® CT-200 excels as a higher performance alternative to PCTFE, a much more insulative material. Parts machined from CryoDyn® CT-200 shapes conduct heat faster and respond to temperature changes more uniformly to maintain their interface with mating surfaces for better sealing performance.
CryoDyn® CT-200 Applications
CryoDyn® CT-200 performance capabilities are ideal for static and dynamic sealing components exposed to a wide range of temperatures. Typical applications for CryoDyn® CT-200 as an alternative to PCTFE include pump and valve seals, turbine seals, and various static and dynamic cryogenic sealing components. The advanced polymer is a particularly effective solution for sealing components that must perform reliably in cryogenic environments such as those encountered in liquefied natural gas (LNG) facilities and transport, and in hydrogen sealing including liquid hydrogen.
CryoDyn® is a Trademark of Drake Plastics Ltd. Co.
Victrex CT is a Trademark of Victrex plc.
