MIL-DTL-24643C
a. Rotary clamp stoppage caused by the circuit continuity monitor (indication specimen conductor breakage),
prior to completion of the specified number twisting cycles (see 3.1).
b. Rupture of the specimen jacket prior to completion of the specified number of bending cycles (see 3.1).
Specimens exhibiting no failure shall be tested further, as specified in 4.8.21.5.
4.8.21.5 Further procedure (may not be required, see 4.8.21.4). The specimen shall be allowed to return to
room temperature and shall be subjected to the voltage withstand test as specified in 4.9.8, using the specified
voltages (see 3.1). Following this, the portion of the specimen which had been between the specimen clamps of the
twisting machine shall be dissected, and each of its constituent components visually inspected for deterioration.
4.8.21.6 Further observation. Either of the following shall constitute specimen failure, except that specimen
damage within 2 inches of the location where either specimen clamp had been fastened shall not constitute specimen
failure, but shall require a complete retest of twisting endurance using a different specimen from the same length of
cable.
a.
Specimen fails the voltage withstand test (see 4.9.8).
b. Specimen, upon dissection and inspection, exhibits visible distortion or cracking of any specimen
component, including strand breakage on any conductor, or exhibits any other visible deterioration of such a nature
or extent as to impair the performance of the cable in service.
4.8.22 Watertightness. This test shall determine the ability of completed cable, which is intended to pass
through watertight bulkheads, to prevent the longitudinal flow of low-pressure water.
4.8.22.1 Specimen. The specimen shall consist of a 60±2 inch length of completed cable. The specimen shall
be cut to length using a scissors-action cable cutter. Saws shall not be used.
4.8.22.2 Special apparatus. Apparatus shall include the following:
a. A source of pressurized water, which shall be provided at a regulated pressure of 27.5±0.5 lb/in2 and which
shall be for use with the terminal fitting (see b) as specified in 4.8.22.3. If swellable water-blocking tapes or yarns
are used within the cable, substitute ocean water mixed according to ASTM D1141 must be used. Otherwise,
normal tap water may be used.
b. A metal terminal fitting which applies the source of pressurized water to one end of the specimen, which
supports the requirements as specified in 4.8.22.3, and which shall be fabricated as specified in the following.
Figure 13 shows one possible arrangement for the terminal fitting. The fitting shall admit the specimen end for the
distance specified in 4.8.22.3, and shall have an i.d., where it fits over the specimen, of not greater than the
measured overall specimen diameter plus ½ inch. The fitting shall have a means for introducing the source of
pressurized water to the specimen end, and means for bleeding off any air which might be trapped between the
specimen end and the source of pressurized water. The fitting shall also have an aperture for introducing a
hardening sealant (see c), to produce a pressure-tight bond between the fitting and the specimen jacket. A plug
(such as a thick wrapping of rubber tape around the specimen) shall be provided at the place where the specimen
enters the fitting, to prevent sealant loss and to approximately center the specimen within the fitting.
c. A liquid hardening sealant which shall be for producing a pressure-tight bond between the fitting and the
specimen jacket, when applied as specified (see 4.8.22.3) and allowed to harden. The sealant shall be at a
temperature of not greater than 100 °C when poured into the terminal fitting, and shall not expand in volume while
hardening. An appropriate metal alloy is recommended as a sealant since it can be remelted and reused. Any metal
alloy used shall have a melting point of not greater than 88 °C.
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