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|  MIL-P-18682D(SH)
3.3.8.5 The design shall insure that positive liquid pressure is supplied
to the seal faces under all conditions of operation and that there is adequate
circulation of the liquid at the seal faces to minimize the deposit of foreign
matter on the seal parts. The pump certification data shall contain certifi-
cation by the seal manufacturer that there will be adequate circulation of liquid
and adequate lubrication at the seal faces when the seal is installed as shown on
the drawing.
3.3.8.5.1 Submarine pumps shall be fitted with mechanical seals and cyclone
separators. Surface ship pumps shall be fitted with cyclone separators when the
pump discharge pressure is 30
gage or above.
3.3.8.6 Stuffing box glands shall be set up by nuts threaded on studs
secured in the castings.
3.3.9 Coupling.
3.3.9.1 For horizontal units, an all metal flexible coupling shall be
installed between the pump and driving unit. Flexible couplings shall be in
accordance with type II, class 2 of MIL-C-23233.
3.3.9.2 Vertical units shall be fitted with a rigid spacer-type coupling
between the pump and driving unit. The design of the pump and coupling shall
permit mechanical seal replacement by removing the spacer without unbolting,
lifting, or otherwise disturbing the driver, the pump cover, or the pump casing.
3.3.9.3 Flexible coupling hubs shall be keyed to the shafts and secured by
lock nuts. The hubs shall be fitted on a taper with keys parallel to the taper.
3.3.9.4 Rigid couplings shall have fitted bolts and the coupling flanges
shall be marked at assembly to insure proper reassembly after overhaul of the
unit.
3.3.9.5 Horizontal flexibly coupled units with bedplates shall have
coupling guards provided. Guards shall permit ready access to the coupling
for lubrication and examination.
3.3.10 Material. The materials of the pump shall conform to the materials
specified in table I. However, this specification is not intended to be restric-
tive provided proposed alternative materials will give equal or better service
than the material specified. Proposed alternative materials shall be subject
to approval by the design review agency. Components of the pump for which the
specific materials are not specified shall be materials best suited for the
intended service. Materials which can be sensitized and are subjected to heat
treatment in the sensitization range during fabrication shall be capable of
passing the intergranular corrosion tests of the base material specifications.
Particular attention shall be given to avoiding sensitization of materials during
hard facing, stress-relieving, or repair welding.
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