MIL-DTL-20078D
ASTM INTERNATIONAL
D 429 - Standard Test Methods for Rubber Property - Adhesion to Rigid Substrates. (DoD
adopted)
D 2240 - Standard Test Method for Rubber Property - Durometer Hardness. (DoD adopted)
(Copies of these documents are available from www.astm.org or ASTM International, 100 Barr Harbor
Drive, PO Box C700, West Conshohocken, PA 19428-2959.)
2.4 Order of precedence. In the event of a conflict between the text of this document and the references
cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes
applicable laws and regulations unless a specific exemption has been obtained.
3. REQUIREMENTS
3.1 First article. When specified (see 6.2), a sample shall be subjected to first article inspection in
accordance with 4.2.
3.2 Material. The material shall be as specified hereinafter.
3.2.1 Rubber. Rubber shall be in accordance with MIL-PRF-900 and shall be suitable for vulcanizing to
steel strip (see 4.4). The hardness shall be 45 plus or minus (±) 5 durometer units (see 4.4.2).
3.2.2 Metal strip. The imbedded metal strip shall be 3/64 by 1 inch hot rolled commercial quality steel
strip, plated as necessary to secure adequate adhesion to rubber.
3.2.3 Adhesion (types A-1 and A-2). The adhesion of the rubber to the steel shall be such that the steel
will bend or the rubber will tear before the rubber can be separated from the steel. It shall not be possible to strip
the rubber cleanly from the steel without the use of solvent when tested as specified in 4.4.3.
3.2.4. Sealing pressure. The sealing pressure of the rubber shall be 95 pounds per square inch (lb/in2)
when tested in accordance with 4.4.4.
3.2.5 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or
environmentally preferable materials should be used to the maximum extent possible provided that the material
meets or exceeds the operational and maintenance requirements, and promotes economically advantageous life
cycle costs.
3.3 Design and construction.
3.3.1 Type A-1 straight section. Straight sections shall conform to Figure 1.
3.3.1.1 At 5-inch intervals along the center of the strip and in the center of the 1/2-inch diameter
recesses in the gasket, there shall be 1/4-inch diameter holes, countersunk for American National Standard No. 10
countersunk head machine screws as shown on Figure 1.
3.3.1.2 Tolerances. The spacing of the holes in the metal strip shall be such that the distance between any
two centers in a strip shall not vary from a multiple of 5 inches by more than ± 1/64 inch. A tolerance of ± 1/4
inch in length will be permitted. Tolerances in width and thickness will be permitted as follows:
Width: plus 1/16 inch, minus 0.0 inch.
Thickness (total): plus 1/16 inch, minus 0.0 inch.
Thickness from un-grooved surface of rubber to metal strip: ± 1/2 inch.
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