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| MIL-V-7501F(SH)
3.6.2.2 Actuation connections. Valves, except type I, class 1, l-inch size, shall have 3/8-inch
salver brazing union actuation connections. The type I, class 1, 1-inch size valves shall have 1/4-inch
silver brazing union connections. Valve union actuation connections shall be furnished complete
with union nuts and tailpieces with pre-inserted rings. Silver brazing actuation union connections
shall conform to the applicable requirements of MIL-F-1 183.
3.6.2.3 Flange finishes. The machine surface finish of gasket mating surfaces on flanges shall
be in accordance with the applicable requirements of MIL-STD-777.
3 . 6 . 3 Threaded parts. Threaded parts shall be in accordance with FED-STD-H28 and all
applicable detailed standards of FED-STD-128. Union threaded ends shall be as specified in
FED-STD-H28 and FED-STD-H28/7. Through bolting shall be the preferred method of joining
mating parts whenever possible. If not possible, the usc of studs is preferred to the use of
capscrews or tapbolts. Bolts and studs shall be of sufficient length to ensure that when nuts are
tightened, there shall be at least one thread projection above the outer face of each nut. Type I,
class 1 removable test fitting extension threads shall be as specified in 3.6.13.
3.6.4 Discs and stems. Valve discs and stems shall be positively guided to prevent binding or
seizing caused by ateral or angular thrust and to ensure proper seating.
3.6.5 Seats. Valve seats shall be integral with the valve body or of non-intergrated removable
design.
3.6.6 Spring. Springs shall be constructed so that they will not be fully compressed under
normal operation or adjustment within the working pressure range of the valve. When removed
from the valve and compressed solid, the springs shall not take a permanent set exceeding 0.10
inch per inch of face length of spring after a 10 minute period at the time the valve is submitted
for test. Springs for hydraulic actuated valves shall be sufficiently strong to close the valve under
no flow conditions with the firemain pressure in the valve. When carbon steel springs are used,
they shall be plastic or rubber coated.
3.6.7 Gaskets and washers. Gaskets and washers shall be constructed of materials suitable
for the services intended (see 6.1). Bearing surfaces of nuts and bolt heads and their respective
mating surfaces on the valves shall be machine finished.
3.6.8 Stuffing boxes. Internal packed stuffing boxes shall not be used.
3.6.9 Atmospheric vent. Type I, class 1, 4, and 5 valves shall have atmospheric vent holes to
provide visual indication of a ruptured diaphragm or leakage past O-rings.
3.6.10 Position indicator. Type I, class 1 valve construction shall incorporate a valve position
indicator. Valve position shall be easily identifiable. Valve full open to full closed positions shall
be within viewing range.
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