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|  MIL-P-18547A(SHIPS)
3.6.13 Couplings.-
3.6.13.1 Unless otherwise specifically approved by the bureau or agency concerned, a flexible coupling of
all metal construction, of a design satisfactory to the bureau or agency concerned, shall be installed between
the pump and the driving unit.
3.6.13.2 Extension shafts when used shall be rigidly coupled to the pump shaft and shall be connected to ,
the transmission drive by a flexible coupling.
3.6.13.3 All coupling hubs, which are to be fitted to driven shafts larger than 1 inch in diameter, shall be
fitted to the shafts on a taper, shall be secured against turning on the shafts by keys fitted parallel to the taper,
and shall be secured on the shafts by lock nuts.
3.6.13.4 Horizontal flexibly coupled units with bedplates shall have coupling guards provided. Guards
shall be designed to permit ready access to the coupling for lubrication and inspection.
3.6.14 Stuffing boxes and packing.-
3.6.14.1 Stuffing boxes shall be of adequate depth and so designed that when properly packed leakage is
reduced to a minimum under all operating conditions.
3.6.14.2 Pump gland packing shall conform to the applicable specifications listed on Drawing B-153. Suf-
ficient space shall be provided between the bearings and stuffing boxes to permit ready renewal of packing and
inspection and overhaul of the bearings.
3.6.14.3 Where a stuffing box is subject to discharge pressure, the design of the box shall be such as to
trap the leakage therefrom by the use of a seal ring, or other method approved by the bureau or agency con-
cerned, and return same by drain piping to the suction side of the pump, with needle valve to control the flow
where necessary. Where a stuffing box is subject to suction pressure, suitable means shall be provided by
seal rings and seal piping connected to the discharge of the pump for sealing the packing to prevent leakage of
air into the pump suction. The sealing piping shall-be fitted-with a needle valve o-r valves as necessary for
proper control.
3.6.14.4 Glands and seal rings, if used, shall be split in halves with the halves secured together in a
manner to form solid rings for setting up.
3.6.14.5 All stuffing box glands shall be set up by nuts threaded on gland swing bolts or studs secured
the casings.
3.6.14.6 Seal rings shall be constructed insofar as practical, so that lantern gland extracting tools in ac -
cordance with GGG-E -950 may be used.
3.6.14.7 Mechanical shaft seals shall be used in all pumps intended for installation on ships having
nuclear powered main propulsion plants and for installation on other ships when specified (see 6.1). Pumps
equipped with mechanical shaft seals shall also have a back-up stuffing box to accommodate a minimum of two
rings of packing for use in the event of mechanical seal failure.
3.6.15 Pump drivers. -
3.6.15.1 Pump drivers shall be of the types, have the characteristics, and be in accordance with the
specifications specified (see 6. 1).
3.6.15.2 Pumps may be direct, geared, or chain connected to the driving units as specified (see 6.1).
3.6.15.3 The continuous duty horsepower (hp.) rating of each motor shall be not less than that required by
the pump when handling the fluid at the temperature and viscosity extremes indicated in 3.5. In addition, the
motor shall be suitable for short time duty rating of one hour driving a pump handling 7000 Saybolt seconds
universal (SSU) viscosity oil. The actual motor rating shall be in accordance with the Navy standard motor
ratings as indicated in the applicable motor specification.
3.6.15.4 Motor controllers. - Motor controllers shall have the characteristics and be in accordance with
the specifications specified (see 6.1).
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