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An Expanded PTFE Gasket is a high-performance sealing material made from polytetrafluoroethylene (PTFE) that has been expanded to create a microporous structure. This expansion process enhances its flexibility, compressibility, and sealing capabilities, making it ideal for a wide range of industrial applications. Unlike traditional PTFE, expanded PTFE offers superior conformability to irregular surfaces, excellent chemical resistance, and long-term reliability in demanding environments.
| Parameter | Value | Test Standard |
|---|---|---|
| Density | 0.4 - 1.2 g/cm³ | ASTM D792 |
| Tensile Strength | 2.0 - 10.0 MPa | ASTM D638 |
| Elongation at Break | 50 - 400% | ASTM D638 |
| Compression Set | 10 - 40% | ASTM F36 |
| Thermal Conductivity | 0.05 - 0.08 W/m·K | ASTM C518 |
| Coefficient of Friction | 0.05 - 0.10 | ASTM D1894 |
| Maximum Service Temperature | 315°C (600°F) | ASTM D1710 |
| Minimum Service Temperature | -268°C (-450°F) | ASTM D1710 |
| Chemical Resistance | Excellent against most chemicals | ASTM D543 |
| Form | Standard Thickness | Standard Width | Custom Sizes Available |
|---|---|---|---|
| Sheets | 0.5mm - 6.0mm | 1000mm x 1000mm | Yes |
| Tapes | 0.2mm - 3.0mm | 12mm - 100mm | Yes |
| Rods | 3mm - 50mm diameter | 1000mm length | Yes |
| Cords | 3mm - 25mm diameter | Coiled or straight lengths | Yes |
| Pre-cut Gaskets | 0.5mm - 6.0mm | Custom diameters | Yes |
| Property | Expanded PTFE | Traditional PTFE | Rubber Gaskets | Compressed Fiber |
|---|---|---|---|---|
| Chemical Resistance | Excellent | Excellent | Good to Poor | Fair |
| Temperature Range | -268°C to 315°C | -268°C to 260°C | -50°C to 150°C | -40°C to 400°C |
| Compressibility | Excellent | Fair | Good | Good |
| Recovery | Excellent | Poor | Good | Fair |
| Creep Resistance | Excellent | Fair | Good | Excellent |
| Sealing Performance | Superior | Good | Good | Fair |
Expanded PTFE gaskets typically handle pressures up to 3000 psi (207 bar) depending on the specific grade, thickness, and application conditions. For high-pressure applications, reinforced versions or specific designs may be required. Always consult technical data sheets for pressure ratings specific to your application requirements.
Yes, expanded PTFE gaskets are suitable for oxygen service when properly cleaned and handled. They meet the requirements for oxygen compatibility when processed according to industry standards such as ASTM G93. However, proper cleaning procedures must be followed to remove any contaminants that could pose ignition risks.
Gasket thickness selection depends on several factors including flange type, surface condition, bolt load, and media being sealed. Generally, 1.5mm thickness works well for standard flanges, while thicker gaskets (3mm+) are used for irregular surfaces or higher compression requirements. Thinner gaskets (0.5mm-1.0mm) are suitable for smooth surfaces and low bolt loads.
Expanded PTFE gaskets are generally not recommended for reuse due to potential compression set and deformation during initial installation. While they exhibit good recovery properties, repeated use can compromise sealing performance. For critical applications, always install new gaskets to ensure optimal sealing integrity.
When stored properly in original packaging away from direct sunlight, moisture, and extreme temperatures, expanded PTFE gaskets have an essentially unlimited shelf life. The material does not degrade over time under normal storage conditions. However, it's recommended to inspect gaskets for damage or contamination before use, regardless of storage duration.
Yes, expanded PTFE gaskets excel in thermal cycling applications due to their excellent thermal stability and recovery properties. They maintain sealing performance through repeated temperature changes from cryogenic to elevated temperatures. The material's low coefficient of thermal expansion contributes to its stability during thermal cycles.
Expanded PTFE gaskets offer superior flexibility, better sealability on irregular surfaces, and higher purity compared to filled PTFE versions. Filled PTFE gaskets (containing glass, graphite, or other fillers) typically have higher mechanical strength but lower chemical purity and less conformability. Expanded PTFE is preferred for applications requiring high purity and excellent sealing on imperfect flanges.
Expanded PTFE gaskets perform well on flange surfaces with finishes between 125 and 500 Ra microinches (3.2 to 12.5 micrometers). While they can seal on rougher surfaces than many other gasket materials, optimal performance is achieved with properly prepared flanges following ASME B16.5 recommendations for gasket surfaces.
Expanded PTFE is resistant to virtually all chemicals except molten alkali metals, elemental fluorine, and certain fluorine compounds at high temperatures and pressures. It maintains excellent chemical resistance across the pH scale and against most organic solvents, making it one of the most chemically resistant sealing materials available.
Yes, expanded PTFE gaskets are suitable for vacuum applications due to their low outgassing properties and excellent sealing capabilities. They are commonly used in high-vacuum systems up to 10-9 torr when properly installed. The material's conformability ensures effective sealing even at low pressures, making it ideal for vacuum chambers and systems.
