Design CAV4
10
Figure 7. TSO (Tight Shutoff) Trim, Detail of Protected Soft Seat
INNER PLUG
OUTER PLUG
CAGE
SEAT RING
PROTECTED SOFT SEAT
A7088 / IL
2. Pull the valve plug and stem assembly (key 4) out
of the cages. Lay it on a protective surface in a safe
location.
3. For stem-balanced valve plugs, proceed to step 4.
For seal ring valve plugs, work the retaining ring (key
10) off the valve plug with a screwdriver. Carefully
slide the backup ring (key 9), two-piece anti-extrusion
ring (key 37), and seal ring (key 8) off the valve plug
(key 4).
For piston-ring valve plugs, the graphite piston rings
(key 11) are each in two sections. If the rings are worn
and need to be replaced, remove the sections from the
grooves in the valve plug (key 4).
For TSO (tight shutoff) trim, perform the following
steps (refer to figures 7 and 8):
Remove the piston ring, anti-extrusion rings,
backup ring, and retainer.
Remove the set screws that lock the outer plug to
the inner plug.
Using a strap wrench or similar tool, unscrew the
outer plug from the inner plug. Do not damage the out-
er plug guide surfaces.
Remove the protected soft seat seal.
Inspect the parts for damage and replace if need-
ed.
4. The upper cage (key 3) has two tapped holes to aid
in removal. Refer to table 7 for the hole diameter and
thread type. Install eyebolts or similar devices into
those holes, then carefully lift the upper cage out of the
valve body.
5. Remove the lower bonnet gasket (key 6).
If removal of the lower cage assembly is necessary,
use a cage retainer tool (figure 6) to remove the cage
retainer (key 5) as follows:
a. Insert the tool into the valve body. Be certain the
tool lugs are engaged in the corresponding re-
cesses in the retainer.
CAUTION
Do not use an impact wrench to remove
or install the seat ring retainer. Damage
to cage retainer, valve body threads, and
lower cage could result.
b. Use a power torque wrench having torque capa-
bilities equal to or greater than those shown in fig-
ure 6. Connect the power torque wrench to a stan-
dard socket wrench extension or other suitable tool.
This extension or tool must fit snugly into the
square hole or hex head of the cage retainer tool.
Refer to figure 6 for square hole and hex head
sizes.
c. Insert the extension into the cage retainer tool.
d. Use the stud bolts (key 28) to prevent the power
torque wrench from rotating.