1. The role of the flat seal
Flat seals prevent, for example, liquids or gases from escaping from pipe connections and systems. They compensate for unevenness between two sealing surfaces and so ensure reliable sealing. The right choice depends on various factors, which are examined in detail below.
2. Key selection criteria
To find the right flat seal, you should consider the following aspects:
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Temperature: Determine the minimum and maximum temperature range of the application. Materials such as graphite or PTFE are suitable for extreme temperatures. Peroxide-cured elastomers also withstand higher temperatures than sulphur-cured ones.
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Pressure: Determine the application and operating pressure. High-pressure applications require more resistant materials such as elastomers with a fabric insert, high-pressure gasket material or fibre composites.
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Medium: Pay attention to the chemical media the flat seal comes into contact with. Aggressive chemicals require highly resistant materials such as ePTFE or special elastomers such as EPDM. As this is a very complex subject, please talk to us if necessary and we will find the suitable material together with you.
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Mechanical load: Take static, dynamic and mechanical loads into account, such as vibrations, oscillations, rotations or flange movements.
3. Material options and their properties
The choice of material is a central aspect when selecting a flat seal. Here are some of the most common materials and their properties:
3.1 EPDM (ethylene propylene diene rubber)
EPDM seals are ideal for sanitary applications. They offer:
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Excellent resistance to water and steam.
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Outstanding resistance to weathering and UV.
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Temperature range: -40 °C to +120 °C.
3.2 Graphite
Graphite seals are suitable for high temperatures and pressures and offer:
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Temperature resistance up to +600 °C.
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Outstanding chemical resistance.
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Very good sealing performance under changing temperatures.
3.3 PTFE (polytetrafluoroethylene)
PTFE seals are suitable for aggressive chemicals and applications with high purity requirements. They are characterised by:
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Temperature range from -200 °C to +260 °C.
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Excellent chemical resistance.
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Low friction and non-stick properties.
3.4 Fibre composites
Seals made from fibre composites offer a good combination of pressure and temperature resistance. Typical applications are found in the petrochemical and automotive industries.
4. Taking norms and standards into account
Compliance with standards is crucial when selecting a flat seal. Here are some of the most important ones:
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DIN EN 1514: Requirements for flat seals for flange connections.
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KTW-BWGL and DVGW: Specifications for drinking water applications.
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ASME B16.21: International standard for flat seals in piping systems.
Conformity with these standards ensures the safety and reliability of flat seals in specific applications.
5. Installation and maintenance tips
Even the best flat seal can only perform optimally if it is installed correctly. Note the following:
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Flange preparation: The sealing surfaces should be clean, dry and free from damage.
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Tightening torque: Use the correct torque to compress the seal evenly.
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Maintenance: Check the seal regularly for wear, cracks, embrittlement, discolouration or other damage and replace it if necessary.
6. Custom flat seals
Sometimes standard seals are not enough to meet the specific requirements of an application. In such cases, custom-made flat seals can be the solution. Siegel Dichtungen, your manufacturer of flat seals of all kinds, offers you:
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Individual adaptation to flange geometries.
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A choice of a wide variety of materials and thicknesses.
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Additional coatings for special requirements.
Conclusion
Choosing the right flat seal is a complex process that requires technical know-how and a precise analysis of the requirements. By taking temperature, pressure, medium and material properties into account and complying with the relevant standards, you can ensure that your flat seal is optimally suited to your application. Contact us for tailor-made solutions that meet your requirements.