Gaskets are materials used to seal one compartment of a device ...

Aramid gaskets are usually composed of 20 percent aramid fiber, by weight,
and 60 to 65 percent fibers and fillers such as silica and clay. The
remaining 20 to 25 percent is the binder which keeps the fibers in a matrix.
Typical applications include off-highway equipment, diesel engines, and
compressors. These applications require a very strong gasketing material that
will withstand moderate temperatures (A.W. Chesterton 1982).
Aramid gaskets as a substitute for asbestos sheet gaskets are used because
of the fiber’s strength and high temperature resistance. Formulations also
include mineral fillers and elastomeric binders. Aramid product costs 1.7
times as much as the asbestos product for some applications, resulting in
gaskets
that cost $9.72 per square yard.
Industry officials project 30 percent of the total asbestos market will be
captured by this substitute (ICF l986a, Palmetto Packing 1986).
2. Fibrous Glass Mixtures
Fibrous glass is generally coated with a binder such as neoprene, TFE,
or graphite in the manufacturing process to make gaskets. Glass fibers are
relatively easy to handle and reduce the costs
of product formulation.
Fibrous glass gaskets are usually divided into two groups, “E” glass gaskets,
and “S” glass gaskets, depending upon the type of glass fiber used in the
formulation. “E”, glass is one of the more common glass fibers, and is
occasionally manufactured into a gasketing which is
used as a jacket around a
plastic core of carbon or aramid fibers and other materials (OGJ 1986).
“E” glass gaskets are suitable for general service applications where the
operating temperature is below 1000°F. Above this temperature, the gasketing
loses 50 percent of its tensile strength. The materials can be used with most
fluids except strong acids and alkalies (A.W. Chesterton 1982).
The second type of glass fiber, “S” glass, was developed by NASA and is
recognized as the superior glass fiber in use today (OGJ 1986). This material
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