High Temperature Gaskets

High Temperatures are Difficult to seal. 

Flexible Graphite high temperature gaskets are commonly used in exhaust applications up to 950 F. But what do you do if your application is beyond what flexible graphite can do? First, you need to recognize that flexible graphite temperature capabilities increase as the level of oxygen present decreases. Exhaust applications by design burn up much of the oxygen allowing flexible graphite to be used in exhaust applications beyond 950 F. However unless you get the level to zero oxygen, it’s likely flexible graphite may max out at 1200 F. So, if your exhaust is at 1400 F or above what do you do?  The answer is Mica.

Mica comes in several forms but  Phlogopite mica and muscovite mica are the two primary forms of mica. Micatherm Mica is a naturally occurring group of silicate minerals. Most sheet mica was produced in India. Flake mica comes from several sources: the metamorphic rock called schist as a byproduct of processing feldspar and kaolin resources, from placer deposits, and from pegmatites. Depending on the grade and type of mica, the conductivity and temperature capabilities can vary. Mica is often blended with silicone which acts as a binding agent to form a gasket material that can later be cut into custom shapes and dimensions. Mica operates effectively at temperatures as high as 1850°F (1000°C) 

Both flexible graphite and mica are added between the windings of spiral wound gaskets. The metal windings combined with metal inner and or outer rings provide the pressure resistance required for high pressure, high-temperature applications.

Mica is available in multiple forms: Laminated, Flexible, or Rigid. For example, you may use a product that is a laminated mica and a tanged stainless steel combination, which is premium grade for high pressures. A flexible mica sheet is produced by combining mica with a polymer by heat treatment. Alternatively, mica is also available as a rigid product.

Both mica and flexible graphite do not have great tensile strength so they can be fragile when a large gasket is cut. This issue is overcome for both materials using the same process of adding a stainless steel tang or foil to the core of the material.

High Temperature Gaskets and Graphite Gasket Material

AS&P HOMOGENEOUS FLEXIBLE GRAPHITE MATERIAL – SWGTB

Flexible graphite sheet made from material typically 98% graphite. Leachable chloride typically less than 50 ppm.  Compressibility: 35%. Recovery: 18%. Creep relaxation: 12%. Density: 62.4 lbs/ft. Minimal tensile strength. Available laminated up to 1/4″ thick.

AS&P 316 S.S. FOIL INSERTED FLEXIBLE GRAPHITE MATERIAL – SWGHR

Flexible graphite sheet reinforced with a 316 stainless steel foil (0.002” thick) made from material typically 98% graphite. Leachable chloride typically less than 50 ppm. Sulfur content: 400 ppm. Compressibility: 35%. Recovery: 18%. Creep relaxation: 12%. Density: 62.4 lbs/ft. Tensile strength: 5000 PSI. Temperature range (oxidizing atmosphere): -400°F to 750°F.

AS&P 316 S.S. TANG INSERTED FLEXIBLE GRAPHITE GASKET MATERIAL – SWGHE

Flexible graphite sheet laminate gasket material with tang 316 stainless steel insert (0.004” thick) made from material typically 98% graphite. Leachable chloride typically less than 50 ppm. Sulfur content: 400 ppm. Compressibility: 35%. Recovery: 18%. Creep relaxation: 10%. Density: 62.4 lbs/ft. Tensile strength: 5000 PSI. Temperature range (oxidizing atmosphere): -400°F to 750°F.

Mica Gasket Material For High Temperatures

AS&P HOMOGENEOUS MICA – ASP-710

A soft conformable phlogopite mica impregnated with silicone. Ensures sealing in applications up to 1000 C (1832 F). Rated to a pressure of 72 psi.

AS&P 316 S.S. TANG INSERTED MICA SHEET MATERIAL – MICATHERM S-15

Micatherm s-15 is a flexible mica sheet bonded with a special resin and tanged insert of 316L stainless steel. The addition of the tang insert helps to improve the pressure rating and handling of the sheet (and large gaskets). Temperature rating to 1,652 F (900 C) Max. Rated to a pressure of 870 psi (60 bar).

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