MIL-DTL-81716A
4.5.2.3 Elongation. This test shall be in accordance with ASTM D1414 using two SAE
AS33931, MS3393-16 packings each for the unaged, air aged, and oil aged tests. The
elongation for the unaged specimen shall not be less than 125 percent. The elongations for the
air aged specimen (see 4.4.2) and oil aged specimen (see 4.4.3 and 4.4.3.2) shall be at least 70
percent of the value obtained for the unaged specimen.
4.5.2.4 Specific gravity. This test shall be in accordance with ASTM D792, except that three
SAE AS33931, MS3393-16 packings shall be used. The specific gravity shall be as determined.
4.5.2.5 Permanent set. Permanent set tests shall be conducted using a suitable tapered
cone and two SAE AS33931, MS3393-3 packings each for the unaged, air aged, and oil aged
tests. The original inside diameter of the packing shall be measured and the packing then shall
be stretched over a tapered cone lubricated with MIL-PRF-5606 fluid until the inside diameter of
the sealing surface has been increased 35 percent. The packing shall be held in the stretched
state for 10 minutes, removed from the cone, and the new inside diameter determined after
waiting 10 minutes. Permanent set (P.S.) shall be calculated as follows:
(I.D. stretched packing in inches (mm))-(I.D. unstretched packing in inches (mm))
P S (%) =
x 100
(I.D. unstretched packing in inches (mm))
There shall be no evidence of breaking or cracking of the test samples. The permanent set
for unaged, air aged (see 4.4.2), and oil aged (see 4.4.3 and 4.4.3.2) samples shall not exceed
3.0 percent.
4.5.2.6 Temperature retraction. This test shall be in accordance with ASTM D1414, except
that three SAE AS33931, MS3393-16 packings each for the unaged and oil aged tests shall be
used and shall be tested in a test set-up similar to Figure 1. The rate of warming shall be 1F
(.5C) per minute. The temperature retraction for both unaged and oil aged (see 4.4.3 and
4.4.3.1) samples at 50 percent elongation and 10 percent return (50/10 reading) shall occur at -
40F (-40C) or lower.
4.5.2.7 Volume change. The volume change of the test sample shall be determined using
three SAE AS33931, MS3393-16 packings and shall be conducted in accordance with FED-STD-
601, method 6211, after oil aging in accordance with 4.4.3 and 4.4.3.2. The volume of the test
sample shall not decrease and shall not increase in excess of 12.0 percent.
4.5.2.8 Corrosion and adhesion. Twelve SAE AS33931, MS3393-16 packings shall be
prepared for corrosion testing by prehumidifying the packings in a desiccator or similar humidity
chamber, maintained at 92 percent minimum relative humidity and room temperature for 72
hours. Metal plates used shall be polished to a surface roughness of 4 to 16 microinches (.1 to .4
micrometers) Ra finish in accordance with ASME B46.1. The edges shall also be polished to
reduce the formation of edge corrosion. Metal plates shall be washed with precipitation naphtha,
as specified in ASTM D91, or similar degreasing agent. The metal plates used shall be as follows
(a set of seven control plates, one of each of the metals tested shall be included):
Aluminum alloy
SAE AMS-QQ-A-250/4, Condition T62
Aluminum alloy
SAE AMS-QQ-A-250/12, Condition T651
Heat Treated to T73
Aluminum alloy
AMS 4029, 2014 Condition T6
Brass
ASTM B36/B36M, C23000
Phosphorbronze
ASTM B139/B139M, C51000
Steel
SAE AMS6345, Condition N
Steel
Cadmium plated per SAE AMS-QQ-P-416
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