Compressed non-Asbestos Fibre Materials (CNAF) Gasket Materials: Uses and Applications

24 May 2018

This gasket family is commonly referred to under its truncated label, CNAF. In its entirety, Compressed Non-Asbestos Fibre materials are exactly that, a gasket type that doesn’t rely on an asbestos base. However, the easily classifiable materials list ends right there, for this is an umbrella term. Many different fibre types and binder groups occupy the CNAF category, and they’re all gifted with their own unique sealing features.

The Principal Material-Defining Factor 

Straight to the point, Compressed Non-Asbestos Fibre gaskets are best-suited for extreme processing conditions. If there are hydrocarbons and oils in the vicinity, or there are solvents and caustic chemicals around, then sheets of CNAF can be cut to fit while they guarantee a fatigue-free seal. Imagine a 0.25 mm thick product functioning as an acid pipe seal. Alternatively, if temperature extremes and high pressures are part of the application’s daily runnings, then an upscaled 3 mm thick sheet will do the job.

Table Selection Methods 

The CNAF category is organized tables. The categorized list, framed in a tabulated form, incorporates glass and aramid fibres, nitrile and other synthetic rubber binders, and all kinds of metallic inserts. As a finger runs down the listed materials, application attributes come to mind. There’s the need for a maximum processing temperature, a matching need for outstanding performance, and a reserved area of the rows and columns that states which hazards are best handled. Typically, the gaskets will maintain their features when solvents and petrochemical oils are the source flow medium. However, this general purpose build adapts to include fibre types that hold strong when steam, refrigerants, and specific chemicals are flowing.

The Multiplicity Factor 

Imagine all of the active chemicals and fluid conditions that dominate countless industrial and commercial applications. A single gasket type will likely satisfy the stringent codes that are enforced by one or two of these sites, but there’s no way they’ll fit every process. That’s the real power of CNAF, the group’s nearly unlimited number of gasketing options. Glass and aramid fibres dominate, but then there are carbon fibres, Kevlar and several other mineral bases. The key, therefore, is to stop this strength from being perceived as a weakness.

The best way to take advantage of CNAF is to be familiar with the material/features tables. Begin by learning about the various mineral bases, refine that approach by assessing mechanical strength. That latter feature could be woven into the fibre or be incorporated as a mild steel ring. Finally, select a binder, a synthetic rubber, that won’t be the weak link in this compounded non-asbestos gasketing solution.

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