-6-
Replacing Packing Continued,
12.
Place the bonnet over the stem and onto the
stud bolts (Figure 4, Key 38) and lubricate with
an appropriate lubricant. If factory lubricated
stud bolt nuts will be used, additional lubrication
is unnecessary. Follow standard bolting
procedures and install the stud bolt nuts (Figure
4, Key 39), ensuring that the body-to-bonnet
joint will withstand test pressures and
application service conditions. Refer to
Table 1 for bolt torque guidelines, unless
accepted bolting procedures demand
otherwise.
13.
Refer to Figures 1 and 2 and install new packing
and metal packing box parts. Using a smooth-
edged pipe placed over the pipe stem,
gently tap each soft packing part into the
packing box. Ensure that air is not trapped
between adjacent soft parts.
14.
Slide the packing follower, upper wiper and
packing flange (Figure 2, Keys 3, 2 and 20) into
position. Lubricate the packing flange
studs (Figure 2, Key 21) as well as the packing
flange nuts (Figure 2, Key 16), and replace the
packing flange nuts.
15.
If using spring-loaded TFE V-Ring packing,
tighten the packing flange nuts using accepted
bolting procedures.
16.
Install the actuator onto the valve body assem-
bly and refer to the actuator instruction
manual for directions on reconnecting
the actuator and valve stem.
Trim Removal
Unless otherwise indicated, key numbers in this section
reference Figure 3 for Design EWD and Restricted Trim,
Figure 4 for Mark EWS and Figure 5 for Mark EWT con-
structions, as well as Class 900 12 x 6-inch construction.
1.
Remove the actuator and bonnet, referring to
Steps 1 through 8 in the Replacing Packing
section.
Note: When lifting the valve plug stem (Key 30) and
the attached valve plug (Key 25) from the valve body,
ensure that the cage (Key 26) remains in the body
(Key 24). If the cage were to drop out of the body after
being lifted partially out, cage damage will result.
Use caution to avoid damage to the gasket sealing
surfaces.
The graphite piston ring(s) (Key 29) in a Mark EWD body
is brittle and in two pieces. Handle with care to avoid
dropping or rough handling of the piston ring(s).
The surface finish of the valve stem (Key 30) is criti-
cal for creating a good packing seal. Also,
the inside surface of the cage (Key 26) is important for
smooth valve plug operation and for creating a seal with
the piston ring (Key 29) or seal ring (Key 50). Seating
surfaces of the valve plug (Key 25) and the seat ring
(Key 32) on a metal-seat construction are important for a
tight shutoff. Protect these parts and their surfaces, and
include them in any inspections.
2.
If packing parts require replacement, remove
them at this time according to instructions in the
Packing Replacement section of this manual.
Remove the cage adaptor (Key 27)
for any restricted trim body through 8 x 4-inches.
Wrap these parts for protection.
3.
Remove the valve plug and stem assembly from
the valve body, setting it on a clean surface. If
the valve plug is being reused, protect the valve
plug seating surface from scratches.
4.
Remove the cage (Key 26) and associated gas
kets (Keys 33, 34 and 35). If the cage becomes
stuck in the valve body, tap the exposed
portion of the cage around the circumference,
using a rubber mallet.
5.
Remove the following parts:
a.
Seat ring (Key 32)
b.
Disc seat (Key 44)
c.
Seat ring gasket (Key 36)
d.
Seat ring adaptor (Key 28)
e.
Adaptor gasket (Key 37)
6.
The Mark EWS and EWT TFE-seat construction
use a disc (Key 45) placed between the
disc seat and disc retainer (Key 43).
7.
Inspect all parts for wear or damage that would
interfere with operation of the control
valve. If replacement or repair of trim parts is
necessary, refer to Lapping Metal Seats or Valve
Plug Maintenance procedures in this manual.
M
ark
EW S
EriES
G
lobE
S
tylE
C
ontrol
V
alVES