Share this page by mail Up to what maximum temperature can expanded graphite gaskets be used?
Expanded graphite gaskets have excellent thermal resistance. However, their temperature resistance depends heavily on the working environment.
In a non-oxidising atmosphere (vacuum or inert gases), expanded graphite can be used at temperatures of up to approximately 3,000°C. However, in the presence of oxygen (air) graphite is subject to oxidation, which lowers its maximum service temperature to around 450–500°C. Above this temperature, degradation will be accelerated.
Final Advanced Materials will use the following criteria to recommend the material best suited to your needs: temperature, pressure, and environment (gaseous, liquid).
If you are seeking a material with high compressibility (>40%) and excellent chemical resistance, graphite is the perfect solution for your needs. It is resistant to over 60 bars of pressure, 550°C in a normal atmosphere, and up to 3,000°C in an inert atmosphere.
However, if you are seeking a material which can resist temperatures ranging between 900–1,000°C in a normal atmosphere and 6 bars of pressure, mica will be a better option. It is both an effective electrical insulator (20 to 80 kV/mm) and an effective thermal insulator (≈ 0.3 to 0.7 W/m·K).
Mica sheets have a good resistance to many solvents, oils and organic chemical agents, as well as high-temperature oxidising environments, making them particularly effective for extreme thermal applications.
However, their resistance is generally limited in the presence of strong bases and strong acids, which can attack the mica structure and degrade the gasket's mechanical properties.
In summary, mica gasket sheets have an excellent overall chemical resistance, especially in moderately acidic environments, but their compatibility depends on concentration or temperature.
Generally, the more irregular the surfaces, the thicker the gasket must be to ensure proper conformability and a tight seal.
However, increasing the thickness also reduces the rigidity of the gasket and may require a higher tightening load to achieve a satisfactory seal. Therefore, it is important to find a balance between defect compensation capability and mechanical strength.
Furthermore, at high temperatures it is important to take both creep and relaxation processes into account: it is often preferable to choose a moderate thickness combined with a compressible and thermally stable material, rather than excessively increasing the thickness.
If the irregularities are too important, Final Advanced Materials can advise you on a textile solution.