Materials

The era of asbestos gaskets, from the perspective of unacceptable health risks, is long gone. Non-asbestos sealing materials have become the unquestionable standard and represent a complex engineering challenge, where it was necessary to replace the unique properties of asbestos (high thermal stability, tensile strength, low price) with sophisticated composites.

Composition of Modern Non-asbestos Composites

Modern non-asbestos sheet materials are vulcanized composites where the interaction between the elastomer binder (matrix) and the inorganic/organic fiber component (dispersed phase) plays a key role. These sealing sheets are manufactured by a calendering-rolling process followed by thermal vulcanization.

1. Fibrous Reinforcing Component

This component ensures mechanical tensile strength, dimensional stability, and resistance to extrusion.

• Aramid Fibers: Provide exceptional tensile strength and modulus of elasticity. They significantly contribute to the high temperature and pressure resistance of the gasket.
• Carbon Fibers: Used for high-end applications requiring extreme chemical resistance (especially against strong acids and alkalis) and increased thermal stability.
• Glass Fibers: Used for applications requiring extreme chemical resistance.
• Mica: Used for applications requiring extreme thermal resistance.
• Mineral Fibers: Primarily serve for thermal insulation and filling, carefully selected for their chemical compatibility with the given medium.

2. Inorganic Fillers

Fillers (powder materials) optimize compressibility, recovery, and chemical resistance.

3. Stainless Steel Reinforcement

To achieve extraordinary mechanical strength of non-asbestos sealing materials, reinforcements (steel mesh, tang core, expanded metal) are used in some types. The material is vulcanized onto the reinforcement during the calendering process.

4. Polymer Binder Matrix (Elastomer Binder)

The binder is an elastomer that functions as a matrix and ensures the homogeneity of the composite, flexibility, and chemical resistance.

• NBR (Nitrile Butadiene Rubber): Excellent resistance to non-polar solvents (oils, lubricants, fuels). The most common binder.
• HNBR (Hydrogenated NBR): Increased thermal and oxidative stability. For hot oils and acidic steam.
• EPDM: Resists polar media (hot water, steam, ketones, alcohol) and weak acids/alkalis.
• CSM (Hypalon): For applications with aggressive media, strongly oxidizing acids, and hot alkalis. Characterized by excellent resistance to ozone, weathering, and low gas permeability.

At ENTRECHAUX, we manufacture custom non-asbestos flat flange gaskets that fully comply with the strictest environmental and safety standards while providing maximum operational reliability.