MIL-PRF-23653D
4.4.4 Fuel and water resistance. Six specimens, each measuring 1 by 3 inches, shall be cut from one tile. Three
samples shall be immersed in JP-5 jet fuel in accordance with MIL-DTL-5624, and three samples shall be immersed
in distilled water. At least 1 liter of test fluid shall be employed and each specimen shall be isolated so that all
surfaces are exposed to the test fluid and each specimen is completely immersed. The samples shall be weighed to
the nearest 0.01 gram prior to immersion. Immersion shall continue at 80±9 °F (27±5 °C) for 96±½ hour. Upon
completion of this period, the specimens shall be removed from the immersion media, excess fluid wiped off, and
the sample weighed again immediately. Percent weight change shall be computed from the following equation:
final weight - initial weight
Percent weight change =
× 100
initial weight
The results from the three specimens for a given immersion medium shall be averaged.
4.4.5.1 Specimen preparation.
4.4.5.1.1 Specimen components. Three large and three small mild-steel disks shall be prepared in accordance
with figure 1. The large steel disks shall be ½ inch thick, have a 4-inch diameter and a centrally-located ½-20 UNC
threaded stud approximately 1 inch long on one face. The threaded stud may be machined as part of the disk or may
be a separate stud threaded into an appropriately tapped hole. Three small steel disks shall be similarly prepared and
shall be ½ inch thick and be 1.597±0.005 inch in diameter. The studs shall be normal to the disk faces. Three discs,
each 4 inches in diameter, shall be cut from one of the damping tiles.
4.4.5.1.2 Specimen assembly. Each damping tile disk shall be cleaned with PF Degreaser (formerly known as
PF-145HP, available from PT Technologies, 4647 Hugh Howell Road, Tucker, GA 30084) or equal degreaser and
allowed to dry thoroughly in ambient conditions. The face of the steel disks without the stud shall be cleaned with
PF Degreaser or equal, then abrasive blasted to SSPC-SP 10 and cleaned with PF Degreaser or equal after blasting.
The degreaser shall be allowed to dry completely before blasting and before specimen assembly. The final
degreaser cleaning shall occur immediately prior to specimen assembly. MIL-A-24456 adhesive shall be mixed in
accordance with manufacturer's instructions and shall be applied with a notched trowel. The notches in the trowel
shall be equilateral triangles 3/16±1/32 inch deep. The triangles shall intersect each other. A damping tile disc shall be
pressed firmly down onto the prepared surface of a large steel disc. Then a small steel disc shall be pressed firmly
down onto the damping tile disc. Excess adhesive shall be removed from the sides of the tile disk where the steel
disks are bonded. Repeat this process for the remaining tile and steel disks (for a total of three sets of adhered
disks). The assembled specimens shall be allowed to set at 80±9 °F (27±5 °C) for not less than 96 hours prior to
testing for adhesion. A drawing of an assembled test specimen is shown on figure 1.
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