Mica Gaskets

Mica gasket material has the capacity to withstand elevated temperatures.

Mica is an alternative to Flexible Graphite in applications over 950 F

High temperature mica gaskets

Mica Gaskets – This material has outstanding resistance to high heat. You may not use Grafoil® or flexible graphite in applications reaching temperatures over 900°F. At high temperatures like such (900°F to1850°F Grafoil and flexible graphitewill cook when oxygen is present. Mica gasket material has the capacity to withstand these elevated temperatures.

American Seal & Packing is now stocked with FMI Micatherm. Our FMI Micatherm product is a mica bound gasket with stainless steel to enhance strength. Our mica gasket material is the best alternative in applications exposing high temperatures up to 1800°F. The presence of oxygen in applications reaching 1800°F allows the mica gasket material to provide a tight seal without failure, time and time again.

This specific gasketing material is special because the main element, Mica, is a mineral which allows it to provide a broad range of useful and abstract properties.

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.

The properties offered by mica have made it a solution to several different applications and could improve the variety of products in your range. Mica is originally formed as flakes. This mineral is completely harmless and executes very high thermal and mechanical performances. The abilities of mica allow it to successfully substitute asbestos gasket material in a number of applications.

Mica Cut Gaskets – Mica cut gaskets are used to fill the space between two objects, typically to obstruct leakage between the two objects while under compression. Cut gaskets allow you to save money through using less precise mating surfaces on machine parts which utilize mica cut gaskets to fill irregularities. The most common production method of mica gaskets is by cutting from mica sheet. Phlogopite mica and muscovite mica are two primary forms of mica.

When phlogopite or muscovite mica is infused with a superlative high temperature resistant silicone resin, the result is a softer and more comfortable gasket.

It is generally a preference that the gaskets be created from a material that is fairly compressible, allowing it to tightly fill the space it’s designed for, including any minor irregularities. The most common mistake made in selecting the appropriate thickness for cut gaskets is choosing a size too thick. This is a problem because if the material is too thick then the material being contained is more susceptible to weeping through the pores of the cut gasket itself. This miscalculation has greater repercussions for some materials than others. A technique frequently used is to have the material thick enough to compensate for any surface face irregularities and to allow some compression. The required compression for your cut gaskets is dependent upon many factors, including:

    1) Mica Gasket Surface Area
    2) Pressure Being Sealed by Mica
    3) Size of Bolts (assuming bolts are being used)
    4) Number of Bolts
    5) Condition of the Bolts
    6) Lubrication on the Bolts

*It is critical to consider these factors in determining torque.

It is common that torque data will be difficult to gather due to staffing and the fear of lawsuits. The exception to this pitfall is if the gasket is a standard ANSI or API Flange using Ring or Full Face. In most cases, it is generally acceptable to tighten it tightly enough to prevent any leaks but not overly tight where the gasket is completely crushed.

A frequent problem to be aware of is over-compression of cut gaskets with metal gaskets, which have mechanically designed recovery built into the gasket. This mishap is applicable to mica filled spiral wound gaskets. When over-compressionoccurs, this removes the cut gaskets ability to recover.

When using elastomeric materials, it is common to use a “The more compressive load exerted on the gasket, the longer it will last” strategy because elastomers are not compressible but instead deflect compression. Many materials such as non-asbestos compressed cut gaskets and beater addition (i.e. Armstrong) materials contain elastomers in the mix of the material they are produced from, making them difficult to over-compress.

The ability to endure high compressive loads is a property that makes mica gaskets one of the most desired in industrial applications. Additionally, due to the fact that most industrial gasket applications incorporate bolts exerting compression well into the 14 MPa (2000 PSI) range or higher, this makes mica cut gaskets one of the most used in industrial cut gaskets applications.

At American Seal & Packing, we understand how specific these applications can be and how important it is to use the correct material. We offer a robust variety of gasket materials to satisfy the requirements and design of your well-defined application. For any assistance in determining which mica gasket material (or other material) corresponds best to your application, please contact the staff at American Seal & Packing today!



    Operates effectively at temperatures as high as 1850°F (1000°C)
    Combats fire without burning
    Low heat conductivity


    Insulation ability stronger than 25 kV/mm
    Quality resistance against arcing and arc erosion
    Permeability to microwaves


    Mica remains immovable by most chemical agents, in particular solvents, acids and bases and mineral oils.


    Superior compression resistance
    Reliable tensile and bending strength
    Significant elasticity modulus


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