.
Replacing Packing Continued,
4. Unscrew hex nuts (key 8) and remove the
bonnet off the valve stem. Ensure the valve
plug and stem remain in the body and on the
seat. This will prevent damage to the seating
surfaces as a result of the assembly dropping
from the bonnet after being lifted out.
5. Should the valve plug and stem assembly start
to lift out, use a brass hammer on the end of
the stem and tap it back down. Set the
bonnet on a cardboard or wooden surface to
prevent damage to the bonnet gasket surface.
6. Upon removing the bonnet gasket (key 5),
cover the opening in the valve body to protect
the surface and prevent any debris from
getting into the valve body.
7. Remove the packing flange nuts, packing
flange, upper wiper and packing follower
(keys 18, 16, 20 and 21). Carefully push the
remaining parts out from the body side of the
bonnet. Take care not to scratch the packing
box wall. Clean the box and metal parts.
8. Inspect components such as valve stem
threads and packing box for any sharp edges
that may damage the packing. If the surfaces
cannot be improved by light sanding, replace
the damaged parts. Scratches or burrs may
cause packing leakage.
9. Remove the protective covering from the
valve body. Install a new bonnet gasket (key
5). Ensure the gasket seating surfaces are
clean and clear of debris. Check that the M-
Flat valve plug, and stem assembly are
oriented as shown in Figure 5 when replacing
the bonnet to the valve body. Slide the
bonnet over the stem onto the stud bolts.
10. Replace the packing hex nuts (key 18)
10a. For pre lubricated hex nuts
(identified by black film coating on the
nut threads) tighten the hex nuts finger
tight.
10b. For all other nuts, CVS Controls
recommends that you lubricate the stud
threads with Never Seez pure Nickel
special lubricant or equivalent.
11. To center trim, the valve will need to be
stroked several times. Using proper bolting
procedures tighten the nuts to no more than
1/4 of the torque values specified in Table 4.
12. Increase the torque on each nut by an
additional 1/4 of the torque value using the
standard crisscross pattern. Repeat this
pattern until the torque values in Table 4 have
been reached. Apply the final torque value
again and if any bolts turn, all of the bolts will
require re-tightening.
13. Using the appropriate packing arrangement,
install new packing and metal packing box
parts. It may be necessary to pre-lubricate
packing parts with a silicone based grease.
14. Using a smooth edged pipe, cautiously tap
each soft packing part into the packing box.
To prevent trapping air between the rings,
add one ring at a time, without forcing them
below entrance chamber of the packing box.
With each additional ring the stack should
only be pushed down the thickness of one
ring.
