MIL-PRF-14442E(AT)
temperature for 24 hours, then weighed to check for excessive vapor loss. The bolts shall be
retorqued if necessary. The cup shall be inverted (test disk down) in a rack that permits free
access of air to the test disk. Cups shall be weighed at the end of the third, fifth, and eighth day
after inverting. Defective films or leaks caused by faulty assembly will usually be found when
weighing on the third day. The diffusion rate calculation shall be made on the fifth to the eighth
day period, and the permeability shall then be determined. Diffusion expressed in fl-oz per ft2 per
24 hours equals the gram loss of the test specimen per 24 hours multiplied by a factor K which is
defined as follows:
K=
144
(sp. gr.) (29.573) (3.1416) (R)2
Where:
sp. gr. = specific gravity of the test fluid at 77°F.
R
= inside radius of test cup expressed in inches.
4.8.4 Tensile strength. To determine conformance to 3.5.7, the tensile strength of a
sample of inner layer ply, without barrier, shall be determined in accordance with the test specified
in ASTM D412, when coated fabric liners are used. The sample shall then be immersed in water
at 180 + 4°F for 72 hours, after which the specified tensile strength test shall be repeated. The
change in tensile strength shall be reported as the after-immersion strength, calculated as a
percentage of the original value.
4.8.5 Seam adhesion. To determine conformance to 3.5.8, the seam adhesion of the inner
layer ply to itself shall be tested along the length of the seam in accordance with the test specified
in ASTM D413, using the strip specimen.
4.8.5.1 Seam adhesion (alternative procedure). To determine conformance to 3.5.8, the
seam adhesion of the inner layer ply to itself may be tested by cutting a strip of inner-layer
material one in. wide, having a seam made in the same manner as is used in the tanks submitted
under 4.3. This seam shall be perpendicular to, and midway in, the length of the strip. A tensile
load shall be applied parallel to the length of the strip, of sufficient magnitude to break the strip.
4.8.5.2 Wet seam adhesion. To determine conformance to 3.5.8.1, a specimen shall be
prepared in accordance with the test of 4.8.5 or 4.8.5.1, and soaked in a test fluid conforming to
referenced fuel B of ASTM D471, for a period of 48 hours, at 75 + 5°F. The specimen shall be
removed from the test fluid and wiped dry. No other means of drying shall be used. Within
4 hours after removing the specimen from the fluid, it shall be subjected to one of the above tests.
The value by the strip method shall be no less than 50% of the dry test value. The results using
the alternative procedure shall require the breaking of the strip outside of seam area.
10
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business