MIL-DTL-24643C
4.8.9.3 Procedure. One end of the cable specimen shall be secured to the curved surface of the cable mandrel
and one end of each insulated conductor specimen shall be secured to the curved surface of the insulated conductor
mandrel, such that all specimens are vertically suspended without obstruction and that free space exists on each
mandrel to accommodate the specimen wrapping to follow. A weight shall be attached to the opposite end of each
specimen such that the suspended portion of each specimen shall remain vertical during wrapping. The refrigeration
chamber doors shall then be closed and the specimen be subjected to an air temperature of minus 40±2 °C for a
period of not less than 20 hours. Prior to any change of chamber temperature the mandrels shall be rotated from
outside the chamber at a rate of 2.5±0.5 r/min, such that the specimens are wrapped around the mandrels for not
fewer than five closely spaced turns. The mandrels shall then be locked to maintain the specimens in their wrapped
position. The chamber doors shall be opened and the specimen secured to the mandrels to prevent the loosening or
unwrapping. The mandrels, with specimens attached, shall then be removed from the chamber and the entire
wrapped portion of each specimen shall be examined using the magnifying glass.
4.8.9.4 Observation. Specimen failure shall be construed if the specimen, upon inspection, exhibits distortion
or cracking of any specimen component or exhibits any other visible deterioration of such a nature or extent to
impair the performance of the cable in service.
4.8.10 Cold working (minus 20 °C). This test shall determine the ability of completed cable, which is not
intended to be flexed during use, to withstand a traveling bend at a reduced temperature, such as might be
encountered during shipboard construction or repair.
4.8.10.1 Specimen. The specimen shall consist of a 20±1 foot length of completed cable.
4.8.10.2 Special apparatus. Apparatus shall include the following:
a. A refrigeration chamber for supporting the requirements as specified in 4.8.10.3. The chamber air
temperature shall be measured in the immediate vicinity of the specimen.
b. Bending apparatus shall consist of two identical sheaves, as shown on figures 6 and 7, which are attached to
a fixed surface such that they are pivoted about their axles and at all times their axles are both horizontal and
parallel, the corresponding points on both sheaves are located in the same vertical plane, their bending surfaces are
separated by not more than four times the maximum specified cable diameter (see 3.1), and they support the
requirements as specified in 4.8.10.3. Each sheave shall have a bending surface width of not more than three times
the maximum specified overall cable diameter (see 3.1) and bending surface diameter of not more than 13 nor less
than 11 times the maximum specified overall cable diameter (see 3.1).
c. Two pieces of rope or twine, each of which shall have a length of not less than 25 feet and shall support the
requirements as specified in 4.8.10.3.
4.8.10.3 Procedure. One end of one piece of rope or twine shall be firmly attached to either end of the
specimen and one end of the second piece of rope or twine shall be firmly attached to the opposite specimen end.
Attachment may be either with a cable grip or by directly tying the rope or twine to the specimen. The specimen
with the rope or twine attached shall be placed within the refrigeration chamber and shall be subjected to a
temperature of minus 20±2 °C for a period of not less than 6 hours. Prior to any change of chamber temperature, the
specimen with rope or twine attached shall be removed from the chamber, and one rope or twine shall be wound
through the bending apparatus into a S shape as shown on figure 6 not more than 20 seconds after removing from
the chamber. The specimen shall be subjected to cold working as follows. The specimen shall be drawn completely
through the bending apparatus at a rate of 35±5 feet per minute by means of pulling on the rope or twine which
initially passes through the apparatus. Immediately thereafter, the specimen shall be drawn completely through the
bending apparatus in the opposite direction, at the same rate, by means of pulling on the opposite end of the rope or
twine. At all times during cold working, both ropes, or twine, shall be directed such that the bending surface of each
sheave is in contact with either the specimen or the rope or twine for an arc of not less than 170 degrees. Following
cold working the specimen shall be dissected for a distance of not less than 3 feet and each of the constituent
components visually inspected for deterioration.
4.8.10.4 Observation. Specimen failure shall be construed if the specimen, either during cold working or upon
dissection and inspection, exhibits distortion or cracking of any specimen component or exhibits any other visible
deterioration of such a nature or extent as to impair the performance of the cable in service.
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