removal. If the coupling is to be removed, the packing box
flange and follower can be removed completely.
3. Using a narrow hook or bent wire, pull the old packing
rings and lantern ring or spring out of the packing box.
CAUTION: WHEN REMOVING PACKING RINGS FROM THE
PACKING BOX, USE A HOOK, BENT WIRE, OR TOOL MADE
FROM A MATERIAL THAT IS SOFTER THAN THE BONNET
MATERIAL. THIS WILL PREVENT SCRATCHING OR MAR-
RING OF THE PACKING BOX SURFACES.
4. Replace packing referring to Figures 4–8 for correct
amount of packing and the correct sequence of instal-
lation.
NOTE
: A thin film of silicone lubricant will ease assembly.
CAUTION: AVOID DAMAGE TO PACKING RING WHEN
SLIPPING THEM OVER THE STEM THREADS.
5. Slide the packing follower over the stem.
6. Place the packing flange, flat side up, over the stem and
flange studs to rest on the packing follower.
7. Screw the packing flange nuts onto the studs and
tighten them evenly to avoid cocking the flange.
NOTE:
Finger tightening of the packing flange nuts should
provide ample sealing pressure to the packing rings. When
the valve is placed in service this adjustment should be
checked, and the nuts tightened just enough to prevent
any leakage. Excessive tightening will bind the valve stem
and prevent sensitive response.
NOTE:
For PTFE V-rings spring loaded, tighten the packing
flange nuts evenly until the packing follower shoulder con-
tacts the top of the bonnet, Figure 4. No further packing
adjustment is required because packing spring compression
maintains the proper sealing pressure on the chevron rings.
8. In some applications, packing boxes are designed for
use with a lubricator. The lubricator is provided with a
ball check valve to prevent back flow of the process
fluid. On some valves, an isolating valve is added for
positive protection against back flow. The lubricator
should be kept filled with the specified lubricant and
turned in firmly but not tightly. One or two turns of the
lubricator once every two weeks should suffice to pro-
vide the desired seal.
3.10 Bellows Sealed Valves
CAUTION: THE TOP OF THE BELLOWS IS WELDED TO THE
STEM AND THE BOTTOM OF THE BELLOWS IS WELDED TO
THE BELLOWS FLANGE. ANY TWISTING OF THESE TWO
PARTS WILL RESULT IN DAMAGE TO THE BELLOWS.
1. Disassembly of a bellows sealed valve follows the same
procedure as Valve Body Disassembly on page 2.
2. Damaged bellows assemblies are replaced as a com-
plete unit.
3. If plug removal becomes necessary, carefully inspect the
portion of the plug shank that can be seen below the
guide bushing. If the pin can not be seen, the bellows
assembly must be held in a vice and the stem moved
downward slightly until the pinned connection is visible.
CAUTION: IN THE RELAXED CONDITION THE BELLOWS
WILL BE AT MID TRAVEL. THE STEM MAY ONLY BE MOVED
DOWNWARD 1/2 OF THE VALVE TRAVEL LISTED IN TABLE 2.
4. If lapping of the plug and seat ring is required, the seat
ring must be removed from the body and hand lapped
to the plug/bellows assembly.
5. Reassembly of a bellows sealed valve follows the same
procedure as Valve Body Assembly.
4
VALVE BODY ASSEMBLY
After completion of the required maintenance the valve
should be reassembled using the following procedures:
4.1
Plug/Stem Assembly
1. Screw the stem solidly into the plug.
2. Place the plug shank on a V-block and using a suitable
size drill-bit, drill the stem using the hole in the plug as
a guide.
3. Remove any burrs from the plug guide by making a
slight counterbore.
4. Select the correct size pin, apply a small amount of
grease on it and press into the hole.
NOTE:
The pin must be recessed approximately 1/16"
below the plug guide surface.
5. After the plug has been pinned, it should be placed in a
lathe to insure it is running "true." If it is not, strike the
plug with a soft-faced mallet to straighten.
4.2
Body Assembly
1. Clean gasket surfaces. Place gasket on gasket surface
on body bridge. Insert seat ring and cage into body.
2. Lower the plug and stem assembly into the body.
3. Place new bonnet gaskets on the body, and lower the
bonnet carefully over the plug stem and body studs to
its place on the body.
NOTE:
The bonnet must be positioned so the packing
flange studs are at a right angle to the flow center line.
4. Install the stud nuts and tighten them evenly to finger
tight only.
5. Insert packing.
NOTE:
Refer to Figures 4–8 to determine correct amount of
packing to install.
6. Slip the packing follower over the stem to rest on the
packing and check to see that it enters the packing box
at least 1/8".
7. Place the packing flange flat up over the stem and
flange studs to rest on the packing follower.
8. Screw the packing flange nuts onto the studs and
tighten them evenly to avoid cocking the flange. Finger
tightening is sufficient.
9. Using the stem, move the valve plug up and down
through the rated travel.
NOTE:
If there is any evidence of binding, loosen the body
stud nuts and reposition the bonnet until the binding dis-
appears.
10. Tighten the body stud nuts to the proper torque listed
in Table 2 using the tightening sequence in Figure 9.
NOTE
: Tighten in 1/3 increments stopping after each
6
