MIL-DTL-917F(SH)
3.2.25 Utilization of standard tools. Insofar as practicable, equipment shall be designed so that only standard
tools, namely, those listed in the Federal Supply Catalog, are required for installation, adjustment, maintenance, and
repair. Tools other than standard tools are designated as special tools. Special tools may be used only when
approved by the contracting activity. Requests for approval of special tools shall be as specified in 3.13.1.3 in which
case "tool" shall be substituted for "part". Special tools shall be furnished by the contractor. Special tools required
for organizational level maintenance shall be mounted securely in each equipment in a convenient and accessible
place, or in a central accessible location for an equipment array requiring such tools.
3.2.26 Equipment insulation requirements. Unless otherwise specified (see 6.2), equipment shall pass
insulation and dielectric withstanding voltage tests required by 3.2.26.1 as follows:
a. The insulation resistance from conductor to conductor and conductor to ground shall be not less than 10
megohms at 77 °F (25 °C). User equipment shall tolerate the test voltage between each power conductor and ground
without equipment damage, arc-over, degradation, or abnormal operation.
b. The dielectric withstand voltage for each circuit shall be determined by the voltage rating of the circuit (or,
if it has no assigned rating, by the maximum voltage of that circuit considering all conditions of equipment operation
at rated voltage).
Equipment using active ground detection shall be tested in accordance with MIL-STD-1399-300. No
equipment damage or malfunction shall result from this dielectric test which insures compatibility with active
ground detectors which superimpose a DC voltage to ground on the normal supply voltage to measure insulation
resistance.
3.2.26.1 Required test. When insulation resistance and dielectric withstanding voltage tests are required, but
the tests and testing procedures are not otherwise specified in the individual equipment specification, the tests and
procedures shall be in accordance with 4.4.1 and 4.4.2. Regardless of whether or not other tests and procedures are
applicable to the internal circuit of equipment, all terminals intended for connection to the ship's power distribution
system at any point (generator feeder, bus feeder, feeder, main, sub-main, branch, sub-branch, and so forth) shall
3.2.27 Special shipboard environmental conditions. The following environmental conditions are applicable to
a limited number of equipment types. These requirements shall be selected for inclusion in those individual
specifications which cover equipment which will encounter these shipboard environments in their application as
specified (see 6.2).
3.2.27.1 Wind speed. Equipment, or portions thereof, exposed to the weather shall operate normally in winds
having a relative velocity of 75 knots (kn) and shall withstand, without damage, winds having a relative velocity as
great as 100 kn.
3.2.27.2 Ice. Equipment, or portions thereof, exposed to the elements, shall start and operate normally when
covered with an ice load of 4½ pounds per square foot (lb/ft2).
3.3 Materials. Insofar as practicable, each item of materials used in the construction of the equipment shall be
of a type, class, form, and grade which is readily available from normal sources of supply. These are standard
materials. Other or special materials may be used only when adequately justified taking into account both the
technical and economic aspects and considering maintenance and support requirements, as well as initial supply.
Technical justification for the selection and use of special materials shall be held by the contractor for inspection by
the Government.
3.3.1 Prohibited materials. Materials of the following types shall not be used:
a.
Toxic pyrolytic materials (see 3.3.1.1).
b.
Mercury (see 3.3.1.2).
c.
Asbestos (see 3.3.1.3).
d.
Silicone (see 3.3.1.4).
e.
Polychlorinate biphenyls (PCBs) (see 3.3.1.5).
f.
Polyvinyl chloride (PVC) (see 3.3.1.6).
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