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

esistance. A wire insert is often added for increased strength in these high
temperature, high pressure applications (OGJ 1986).
Graphite is an expensive material, but the addition of various fillers
helps keep the cost competitive with other substitute materials (Palmetto
Packing 1986). The cost of replacement gaskets made from graphite are
approximately two times that of the asbestos gaskets they will replace based
on fiber requirements and processing costs (Union Carbide 1987). The price of
the substitute material is, therefore, $11.38 per square yard. Industry
officials project this substitute’s market share to be 15 percent of the total
asbestos gasketing market (Palmetto Packing 1986, Union Carbide 1987, ICF
l986a).
4. Cellulose Fiber Mixtures
Cellulose
fibers are generally milled from unused or recycled
newsprint or vegetable fiber in the presence of additives which ease grinding
and prevent fires
during processing.
Manufacturers of sheet gaskets that contain cellulose fiber consider their
specific formulations proprietary. These producers, however, indicate that
these
fibers are generally used with a combination of clay and mineral
thickeners. The gaskets made from cellulose products have a content of
between 20 and 25 percent cellulose fiber and 50 to 55 percent fillers and
thickeners. The remaining 25 percent is usually an elastomeric binder (ICF
1986a).
Traditionally, cellulose fiber gaskets are only used at low pressure (