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Page Title:
Suction and discharge connections |
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|  MIL-P-17639F(SH)
3.3.3.12 Venting. Pump casing shall be self-venting or be provided with
casing vents. Those portions of the casings which might trap air, but are not
vented , when the pump is secured, shall be. rapidly cleared of air by flow during
pump operation. Special attention shall be paid to the vent location so that
the seal lubrication requirements of 3.3.8.5 are met during pump start-up and
operation.
3.3.3.13 For pumps with suction and discharge connections which are pre-
pared for welding to the system piping, the vent connections shall be located
on parts of the pump which do not need to be removed for repair or maintenance
and shall be configured for welding the system venting piping directly to the
pump. If, in order to perform its intended function, the vent connection must
be located on a removable part of the pump, then the vent connection shall be
flanged for mating with flanges.
3.3.3.14 The bottom of drip pockets shall be tapped for drain connections.
3.3.4 Suction and discharge connections.
3.3.4.1 Unless otherwise specified (see 6.2.1), suction and discharge
connections shall be flanged for mating with flanges in accordance with
MIL-STD-777 or MIL-STD-438 for the applicable system.
3*3.4.2 Suction and discharge connection of split case pumps shall be
on the fixed half of casing except on close-coupled pumps.
3.3.5 Impellers.
3.3.5.1 Unless otherwise specified in the contract or order (see 6.2.1),
impellers shall be of the closed type. Outside surfaces of impellers shall be
smooth finished.
3.3.5.2 Impellers shall be keyed on the shaft and securely held against
lateral movement by locked nuts or other means approved by the design review
agency.
3.3.5.3 Impellers shall not be furnished with wearing rings. Impeller
hub wearing surfaces shall have material thickness to permit reducing the
diameter of the impeller hubs by as much as 0.050 inch to accommodate undersize
casing wearing rings to restore design running clearance.
3.3.5.4 Each impeller shall be dynamically balanced in accordance with
MIL-STD-167-1.
3.3.5.5 For seawater pumps, O-rings and gaskets are prohibited from being
in contact with highly-alloyed corrosion resistant steel parts.
3.3.6 Shafts.
3.3.6.1 Shaft threading, except threading for rolling contact bearing
locknuts, shall be counter to the direction of rotation. Shaft threading for
rolling contact bearing locknuts may be clockwise or counterclockwise.
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