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|  MIL-P-18682D(SH)
sleeve, and if there is a maximum allowed time between initial
wetting of that compound and final positioning of the mechanical
seal in the pump, then do not perform that final positioning
until the maximum allowed time has clasped.
After installation, the mechanical seal shall be run-in and the
(b)
pump operated for at least 4 hours at maximum rated speed with
the pumped fluid at maximum operating temperature and with pump
suction pressure as high as feasible without requiring pump test
loop modifications. The seal leak rate shall then be measured
and recorded. Also, the dynamic balance shall be measured and
recorded using a vibration indicator of the neon tube or similar
type capable of measuring vibrations of 0.001 inch or less.
During subsequent pump disassembly, the final axial position of
the mechanical seal shall be measured and recorded if the pump
design permits.
Acceptance criteria: Mechanical seal leakage shall not exceed 5 drops per
minute. The pump and drive shall exhibit no abnormal noises or roughness of
operation. Vibration shall not exceed the limits specified in MIL-STD-167-1,
type II, measured on the bearing caps. The mechanical seal shall have been
positioned at the axial position recommended by the mechanical seal vendor to
generate the proper amount of mechanical seal spring force. The mechanical seal
vendor shall provide in writing his recommendation regarding the axial position
in his concurrence that the mechanical seal alinement test results demonstrated
proper positioning of the seal. If it was not practicable to measure the axial
position of the mechanical seal, then the seal vendor shall concur that the
recorded force used to position the seal during assembly was acceptable and
shall state the technical basis for considering that force acceptable. A copy
of these mechanical seal vendor documents shall be provided as part of the test
report.
4.6.6.3 Packing and alinement test. The mechanical seal shall not be
installed during this test. The pump shall be packed and alined precisely in
accordance with the procedures stated in the proposed technical manual. The
packing shall then be run in the pump and operated for at least 4 hours at a
maximum rated speed with the pumped fluid at maximum operating temperature and
with pump suction pressure as high as feasible without requiring pump test loop
modifications. The time of day of each packing leakage measurement and of each
packing adjustment shall be recorded. The dynamic balance shall be checked with
a vibration indicator. After the tests, the packing and shaft sleeve shall be
inspected and the results recorded. If the rated maximum operating temperature
exceeds
and the normal operating temperature is less than or equal to
the packing and alinement test shall be repeated satisfactorily with the
pumped fluid at normal operating temperature.
Acceptance criteria: The stabilized packing leak rate, defined as that
measured at least 30 minutes after the last packing adjustment, shall be within
the limit recommended by the pump vendor. Vibration shall not exceed the limits
specified in MIL-STD-167-1, type II, measured on the bearing caps. There shall
be no smoking or scorching of packing and no scoring (vice polishing) of the
shaft sleeve.
40
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