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TM 5-3825-220-13&P
6-4.13 Aluminum Gate Valves
a.
Aluminum gate valves are used thru out the TPT system. See para.'s under 2-5.3 for technical descriptions.
See Appendix A for manufacturer's data on the valves furnished (Milwaukee Valve Co. and Morrison Bros. Co.). Fig.
6-19 shows a cross section of a typical aluminum gate valve for maintenance instructional purposes.
b.
Recommended corrective maintenance actions are as follows.
1.
Packing gland leakage that is not stopped by tightening the packing nut indicates that repacking is
necessary. To repack (after making sure the valve is depressured or alternatively removed from system), unscrew the
packing nut completely. Remove the old packing. Clean out the gland and insert new packing rings. These are split
rings and they can be installed without removing the hand wheel. The hand wheel may be removed first if desired. This
will permit the packing nut to be removed and the packing rings may be slipped over the stem without spreading the
rings. When repacked, replace and tighten the packing nut. Replace the hand wheel and return the valve to service.
2.
When repacking, inspect the stem for scoring or wear. If either is present, this could be the cause of
packing wear and leakage. In this case, the stem should be replaced. It is recommended that this be done in a qualified
shop. See 4 below.
3.
If the bonnet joint leaks and the leakage cannot be stopped by tightening the bonnet bolts, the valve must
be partially disassembled to replace the bonnet gasket. To do so, remove the bonnet bolts and turn the hand wheel
counterclockwise until the upper stem disengages from the lower stem. Lift off the bonnet together with the upper stem
and hand wheel. Clean the bonnet seating surfaces and replace the bonnet gasket. Replace the bonnet and engage the
upper stem to the lower stem threading (worm) turning the hand wheel clockwise until fully engaged. Replace and
tighten the bonnet bolts.
4.
If the valve will not close tightly, open fully, leaks past the valve seat, or leaks at the gland in spite of
repacking, it must be removed from service, disassembled and repaired. It is recommended that valves in this condition
be replaced and that the faulty valve be passed up thru maintenance channels for internal inspection, overhaul, or other
disposition.
5.
If valve leaks at the flanges, treat it as in para. 6-4.12.
6-4.14 Ball Valves
a.
The ball valves supplied with the system are specified in para.'s 2-5.3h, j and m. Complete maintenance
instructions are contained in Appendix A (Pittsburgh Brass Mfg. Co.) and will not be repeated in detail here. For
maintenance convenience, a cross section of a typical ball valve is shown in Fig. 6-20.
b.
Other than repacking or tightening the body tie bolts, maintenance of ball valves in the field is not recommended.
Fortunately, the service life of ball valves is good.
1.
To repack, remove the valve from service and proceed as described in the Pittsburgh Brass Co. literature
in Appendix A.
6-20
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