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

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major categories according to the type of non-asbestos substitute used (Table 3 presents properties of the substitute fibers): a aramid mixtures, a fibrous glass mixtures, • graphite mixtures, • cellulose mixtures, and • PTFE mixtures (ICF l986a, Palmetto Packing 1986). The current market share of the different substitute formulations is estimated to be as indicated in Table 4. Industry experts have indicated that asbestos sheet gaskets account for approximately 50 to 60 percent of the current market. It is evident, however, from the survey that the market share of asbestos free sheet gaskets is increasing rapidly, as companies replace asbestos in some applications. One obstacle to complete replacement of asbestos gaskets by substitute products is military contract specifications that stipulate the use of asbestos gaskets. This includes aerospace and Naval specifications. A 100 percent asbestos-free market is impossible to achieve if military specifications continue to require asbestos products. 3 1. Arainid Mixtures Aramid fiber products are produced by numerous companies from DuPont’s Kevlar(R) and Nomex(R) fibers. Kevlar(R) and Nomex(R) were introduced in late 1980 to act as reinforcing fibers in asbestos free gaskets and other materials. They are highly heat resistant and strong (ten times stronger than steel, by weight). They are about twenty times more expensive than asbestos, by weight. Because it is less dense and stronger, however, less is needed for reinforcement purposes. At high temperatures (above 800°F),the fiber physically degrades, but it is very strong and can withstand very high pressure up to the temperature limit (A.W. Chesterton 1983). ~ Department of Defense branches seem willing to follow EPA requirements and reconunendations for new equipment, but for existing equipment, revalidation with a new gasketing material would be very costly (DOD 1986). -6-
Table 3. Substitutes for Asbestos Sheet Gasketing Product - Advantages Disadvantages Remarks References Aramid Very strong. Year resistant. High tensile strength. Hard to cut. Wears out cutting dyes quickly. 80O~Ftemperature limit. ICF 1986a, ICF 1985, Mach. Des., July 10, 1986 Fibrous Glass Good tensile properties. Chemical resistant. More expensive than asbestos. Often used in the auto industry. ICF 1986a, ICF 1985, Mach. Des., July 10, 1986 Graphite Expensive Heat resistant to 5000’F. Chemical resistant. Light weight. Brittle. Frays. Fastest growing substitute in the auto market in high temperature seals. ICF 1986a, ICF 1985, Mach. Des., July 10, 1986 Cellulose Inexpensive. Good carrier web. Not heat resistant. Useful to 350’F. Not chemically resistant. Useful for low temperature applications only. ICF 1986a, ICF 1985, Mach. Des., July 10, 1986 PTFE Low friction. Chemical resistant. FDA approved to contact food and medical equipnent. Not as resilient as asbestos. Deforms under heavy loads. Used primarily in the chemical industry. ICF 1986a, Palmetto Packing 1986 a Ceramic High temperature limit. Flexible. Inccmipatible with sone binders. No test data. Secret Filler. ICF 1986a
Page 1 and 2: XXVII. SHEET GASKETS A. Product Des
Page 3 and 4: Table 1. Fluid and Pressure Ranges
Page 5: $20.5 million in 1985, based on an
Page 9 and 10: Aramid gaskets are usually composed
Page 11 and 12: esistance. A wire insert is often a
Page 13 and 14: 6. Ceramic Fiber Mixtures Ceramic f
Page 15 and 16: REFERENCES Carborundum. 1986. Produ
Page 17 and 18: Bulk Square braád Rolled (over cor
Page 19 and 20: Table 1. Standards of Asbestos Yarn
Page 21 and 22: A. ‘I’ A. ‘-I PRESSURE ~ Movi
Page 23 and 24: Table 2. Operating Conditions and U
Page 25 and 26: Table 3. Production of Asbestos Pac
Page 27 and 28: een forced to replace the asbestos
Page 29 and 30: Table 4. Estimated Market Share for
Page 31 and 32: useful temperature limit of approxi
Page 33 and 34: 6. Other Substitute Fibers Other fi
Page 35 and 36: Table 6. Data Inputs for Asbestos R
Page 37 and 38: TSCA Section 8(a) submission. 1982.
Page 39 and 40: a viscosity control for waterproofi
Page 41 and 42: Table 1. Production of Asbestos Roo
Page 43 and 44: or talc. The additives ease grindin
Page 45 and 46: Table 2. Manufacturers of Cellulose
Page 47 and 48: Cellulose bodied roof coatings and
Page 49 and 50: equivalent basis, they are favored
Page 51 and 52: compounds. These formulations have,
Page 53 and 54: . Other Roof Coatings and Cements O
Page 55 and 56: Table 4. Data Inputs for Asbestos R
Page 57 and 58:
ATTACHMENT B PROJECTED PRICES ANALY
Page 59:
ICF Incorporated. 1986 (July-Decemb
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