Flowserve Cast Flex Wedge Gate Valve - Manual (Page 14)

Cast Flex Wedge Gate Valves FCD ADENIM0010-02
14
5.0 VALVE MAINTENANCE
(Continued)
5.3
Cleaning
The frequency and extent of cleaning will depend on the valves' location and service conditions. It is important that
the stem and packing gland parts be kept clean and free of foreign material. Do not allow water or dirt to collect in the
body neck bore area above the pressure seal of pressure seal valves. The build up of corrosion or extraneous
material may interfere with removal of the bonnet. For the same reason, excessive rust should not be allowed to
build-up on the body-bonnet bolting of bolted bonnet valves
.
5.4 Packing
Most grafoil Anchor/Darling gate valves are supplied with packing with braided graphite end rings unless otherwise
specified.
1. Unbolt gland bolts and raise gland flange and gland. These two parts may be held out of the way with wire or twine.
To prevent the loss of the two gland nuts, thread back on the gland bolts.
2. If the valve is being repacked, remove the old packing with a packing hook. The lantern ring in double packed
valves should also be removed with the packing hook, utilizing the holes drilled in the top of the lantern ring, which, in
the case of larger valves, are threaded. This feature permits the use of threaded rods for removal in difficult cases.
During these operations take care not to scratch the stem.
3. After the old packing is removed, inspect the stuffing box for cleanliness. Blowout with compressed air if available.
4. Install new rings one at a time in the sequence shown on the valve assembly drawing (Fig. 12). Be careful that the
cut ends of the rings butt together and do not overlap. This is particularly important when packing is cut from roll
stock. Install the rings with the butt joints offset 180° from each other. Do not use a pointed instrument to push the
rings into position. A packing iron should be used for this purpose. The ability of packing to seal the stem is
dependent on the amount of loading that each individual ring receives. It is particularly important for the bottom rings
in the stuffing box to be forced tightly into place. This is most easily accomplished by ramming the rings into place
with the packing iron. When packing double packing boxes with leak-off, it is essential that sufficient rings of lower
packing be installed to position the lantern ring at the level of the leak-off. When the stuffing box is full, tighten the
gland nuts evenly to ensure that the gland is concentric with the stem. Cocking of the gland or gland flange can cause
binding and scoring of the stem.
5. Operate the valve once to verify that the packing is not too tight and binding the stem.
Figure 6