In order to get a good understanding of the potential uses for PTFE energized seals, this blog post will take a look at three specific areas these seals are commonly used:
- cryogenic media
- medical devices
- oil & gas operations
Well also look at what properties of PTFE make it so well adapted to these applications.
1. Sealing Cryogenic Fluids
Cryogenic applications require materials that remain functional at extremely low temperatures and are not subject to explosive decompression. In addition, many cryogenic designs prohibit the use of the lubricants, which makes a dry running lip material necessary. Another important design requirement is a polymer jacket material that is chemically non-reactive.
PTFE meets all of these requirements, making PTFE energized seals an excellent option for cryogenic applications. Typical places where you may find PTFE energized seals include the transportation of cryogenic liquids (such as LNG loading arms) and their use in aeronautics (working with hypergolic fluids and propellants).
2. Medical Devices
The medical industry requires energized-seal jacket materials that can be sterilized (e.g., harsh chemicals, hot water, steam), qualify as USP Class VI materials, and retains its strength over both a range of pressures and temperatures. PTFE is resistant to steam, hot water, and the majority of harsh sterilization chemicals used by the medical industry. There are PTFE grades that are both FDA approved and approved as USP Class VI materials. PTFE also retains its strength in the presence of extreme temperatures and pressures.
PTFE energized seals are used in a variety of medical devices, including both reusable and disposable applications. Such uses include:
- drug delivery systems
- surgical tools
- instrumentation
- pharmaceutical manufacturing equipment
3. Oil & Gas Operations
One of the key factors behind both elastomeric seal failure in oil and gas applications involves extreme temperatures, including steam. Over time, steam exposure can cause many materials to become brittle, crack, and fail — and failure is not an option when it comes to petrochemical processing.
There is also high pressure involved, with typical operating pressures ranging from 1,500 to 15,000 psi (and in some cases even reaching 25,000 psi). Such high pressure can drive down the glass transition temperature of materials, causing them to behave as a brittle material (a common occurrence in subsea applications). Another key issue is the corrosive media involved.
Once again, PTFE-jacketed energized seals are ideal for these types of oil and gas situations. PTFE can handle steam and hot water, as well as aggressive chemicals such as sour gas and acid gas. PTFE also works well even in the presence of high temperatures and extreme pressures. PTFE energized seals can be found in these typical oil and gas applications and more:
- turret swivels
- subsea equipment
- transfer systems
- pumps
- compressors
Conclusion
PTFE-jacketed spring energized seals are an excellent option when factors such as exposure extremely aggressive chemicals, extreme temperatures, high pressures, or FDA approval are design constraints. PTFE remains the first choice for many sealing applications because of its low friction, dry running capabilities, chemical resistivity, and strength.
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