Gasket Types – Part II

Basic Non-Metallic Gasket Material


Compressed Fiber Sheet MaterialsCompressed gasket materials make up the vast majority of gaskets most commonly used. This is primarily due to the fact that gaskets made from compressed materials can be easily fabricated to fit any shape and size flange in a wide range of application, making these types of gaskets very common and cost effective.

Compressed gasket material generally falls within one of the following three categories. Keep in mind that gasket material manufacturer’s have different names for equivalent gasket materials within each of the three classes of gasket sheeting material.

Compressed Synthetic Gasketing (CSG)PTFE (Teflon) Sheet, and Flexible Graphite Sheet.

Compressed Synthetic Gasket (CSG) Material

A very popular sheet material in this category is made with Aramid Fibers/NBR Binder.  The aramid fiber is also known as Kevlar.  Gasket material made from aramid fibers have good wear resistant qualities with a very high tensile strength.  The binder (which is the material used in the hot calendaring process that helps bond the fibers together) is nitrile rubber (NBR).  Compressed Synthetic Gasket material is a very good general service gasket material that has numerous applications in the process industries and in the water and wastewater industry. It is also commonly used in equipment such as valves and pumps.

Other popular fibers used in compressed sheet material is carbon, cellulous or vegetable fibers.

PTFE (Teflon) Sheet

PTFE is generally used because of its outstanding chemical resistance. Note that it can be prone to relaxation and creep. Therefore, expanded or filled grades such as are often employed to overcome some of these effects.  PTFE can be used as a cover around the inside edge of a fibre joint, to produce what is known as a PTFE envelope gasket, as well as being used as a filler in spiral-wound gaskets, and as a covering surface layer for Kammprofile gaskets.

Flexible Graphite Sheet

A commonly used style of flexible graphite sheet comes reinforced with a 316ss foil, .002” thick.  The flexible graphite sheet is made from exfoliated graphite flake which is compressed into foil by a carefully controlled calendaring process. In this process, the expanded flake particles are mechanically locked together without the use of fibers, binders or other additives. Sheets of foil are then adhesive bonded and laminated to the required thickness with the 316ss foil core in the center.

Flexible graphite sheet has pressure-temperature sealability capabilities that are far superior to all asbestos reinforced and non-asbestos reinforced sheet products. It is resistant to chemical attack by virtually all organic and inorganic fluids with the exception of concentrated, highly oxidizing acids.

Steven Liparoto -Denver Regional Sales Manager


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