Sealing applications involving low temperatures can be problematic to service. Gaskets for low temperature applications have to surmount two problems:
At low service temperatures, many standard gasket materials harden, stiffen and become less compliant, meaning that the gasket will not deform once a load is applied. This lack of deformation reduces the gasket’s ability to conform to the sealing surfaces of a joint or flange and compromises the sealing performance of the gasket.
Low service temperatures can alter a gasket’s compression set. In low temperature environments, a gasket can acquire a compression set and, should the service temperature rise, the gasket can consequently leak.
What are low temperature applications?
In Canada, winter outdoor temperatures can go down to -30°C to -40°C (-22°F to -40°F) or even lower. Gaskets used to service sealing applications in Canada where there will be outdoor exposure should be capable of supporting these temperatures.
In industrial applications, cryogenic processes and those involving liquefied gases and refrigerants can have service temperatures at or below -150°C (-238°F). The term “cryogenic gasket” is given to gaskets that have to seal in an application temperature below 0°C (32°F).
What gasket materials can service low temperature/cryogenic applications?
Gasket elastomers tend to become harder or softer as the ambient temperature decreases/increases. Different elastomers have varying responses to temperature ranges and extremes. For this reason, not all general-purpose elastomers are suitable for producing gaskets that need to service low temperature applications.
For servicing low temperature and cryogenic applications, two types of gasket materials are preferred: silicone and PTFE. Because each material has different grades and variants, it is always wise to check carefully with a gasket supplier as to which grade is best for a specific low temperature application.
Silicone gaskets will generally remain flexible and compliant at application temperatures down to -60°C (-76°F), while some types, such as phenyl-based silicone, will service application temperatures as low as -90°C (-130°F). Fluorosilicone (FVMQ) gaskets can be used in oil and fuel applications with service temperatures down to -75°C (-103°F).
PTFE (Teflon™) gaskets are the preferred choice for cryogenic service. PTFE gaskets will service temperatures down to -185°C (-300°F). While PTFE gaskets will not harden or stiffen at these low temperatures, the material can tend to creep.
When choosing gaskets for low temperature applications, it is important to consider the temperature range to be serviced, and not just the lowest extreme of the service temperature range. In every case, you will want to choose a gasket material that can service both the lower and upper temperatures that will be experienced within an application.
If you are seeking gaskets for low temperature applications, CRG can help. We carry an extensive range of gasket materials and can advise on the preferred material for your low temperature application. All gaskets we produce are manufactured under controlled conditions in our ISO 9001-certified facility using the latest CNC production equipment.
To find out more about how we can service your low temperature sealing needs, please contact our sales team at email@example.com.