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|  MIL-V-18683A(SHIPS)
3.3.4.2 The use of ball bearings shall be subject to the speed limitations of FF-B-171 except where prior
approval of the command or agency concerned has been granted.
3.3.4.3 Installation.
3.3.4.3.1 Bearings shall be installed in housings separate from and independent of the stuffing boxes and
with adequate protection from gland leakage. Suitable means shall be provided-to prevent escape of lubricant
around the shaft. All baffles, wipers , and related parts shall be readily renewable.
3.3.4.4 Lubrication of the ball bearings shall be in accordance with FF-B-171.
3.3.5 Motors.
3.3.5.1 All motors for driving pumps shall be of the types and characteristics specified (see 6.1), and
shall conform to MIL-M-17413 or MIL-M-17556 for direct current (d.c.) motors, or MIL-M-17059 or MIL-M-17060 for
alternating current (a.c.) motors.
3.3.5.2 The horsepower rating of each motor shall be not less than the maximum brake horsepower of the
driven pump under any condition from shut-off to free delivery. The actual motor rating shall be in accordance
with Navy standard motor ratings, If the maximum brake horsepower of the pump is less than 2, and if there is
a possibility of an unpredictably high frictional load due to improper adjustment of the gland or to some other
cause, then the maximum brake horsepower shall be multiplied by a safety factor 1.5 -
before select-
ing the next larger Navy standard rating,
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3.3.6 Controllers. All motor controllers shall be of the characteristics specified (see 6.1) and shall
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conform to MIL-C-2212 for both a.c. and d.c. controllers,
3.3.7 Shockproofness.
3.3.7.1 The design of all complete pumping units shall be such that they are capable of passing the grade
A, hull mounted, class I, medium weight, type A-shook requirements specified in MIL-S-901 (see 4.4.7).
3.3.7.2 Shockmounts shall not be used unless command or agency approval of the mount and its proposed
application is given.
3.3.7.3 The determination of stresses resulting from the shock tests is accomplished by the application
of the usual methods of analytical mechanics. The allowable stress in parts due to shock shall be the yield
strength (0.2 percent offset of the material. Normal stresses in parts, such as the tensile stress in a bolt
due to initial pull-up shall not be added to the shock stresses. It is of paramount importance that the max-
imum accelerations possible under the shock tests be utilized in the design of holding down bolts, supporting
feet or lugs, and main structural members of the equipment, and that no failure or permanent deformation occur
as a result of shocks. Parts of an assembly mounted on a common rigid base need not be designed for higher
accelerations than the values for which the whole assembly is designed unless the designer has reason to
believe that higher accelerations will be experienced by the parts.
3.3.7.4 Bolts designed to be stressed in shear shall be installed in holes with a minimum of clearance.
Hole diameters shall be no more than 1/32 inch larger than the bolts for sizes UP to and including 3/4 inch,
and no more than l/16 inch larger than bolts of 3/4 inch size.
3.3.8 Painting.
3.3.8.1 For pumps operating at a temperature of
or lees, all external unmachined surfaces of ungal-
vanized ferrous metal parts shall be thoroughly cleaned and coated with one coat of pretreatment, in accordance
with MIL-P-15328, and one coat of zinc chromate primer in accordance with TT-P-645, or one coat of red lead
primer in accordance with MIL-P-17545, followed by a finish coat of light gray equipment enamel in accordance
with MIL-E-15090.
3.3.8.2 Painting of external surfaces of nonferrous parts of pumps will not be required,
3.3.9 Threaded parts such as bolts, studs and nuts shall conform to MIL-B-857 and Handbook H28.
3.3.10 Welding shall be in accordance with MIL-STD-278 except for the welding of the seal tank.
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3.4 Detail requirements.
3.4.1 Casings.
3.4.1.1 The easings of all pumps shall be designed giving maximum consideration for accessibility and
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ease of replacement of packing, mechanical scale, bearings, and wearable parts such as rotors.
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