Instruction Manual
D100425X012
YD and YS Valves
July 2017
19
can be installed. If the existing valve plug is reused, and the adaptor is in good condition, it may also be reused. However,
never reuse an old adaptor with a new valve plug. Using an old adaptor with a new valve plug requires drilling a new pin
hole in the adaptor. This drilling weakens the adaptor and may cause failure in service. However, a used valve plug may be
reused with a new adaptor.
3. Inspect the existing valve plug and adaptor. If they are in good condition, they can be reused with the new
stem/bellows assembly and they do not need to be separated.
CAUTION
When removing/installing a valve plug on the ENVIRO‐SEAL stem/bellows assembly, the valve stem must not be rotated.
Damage to the bellows may result.
Do not grip the bellows shroud or other parts of the stem/bellows assembly. Grip only the flat areas on the stem where it
extends out of the top of the bellows shroud.
Note
The ENVIRO‐SEAL stem/bellows assembly has a one‐piece stem.
4. If the valve plug and adaptor are not in good condition and must be replaced, first remove the valve plug/adaptor
assembly from the stem/bellows assembly; then remove the valve plug from the adaptor. First, place the
stem/bellows assembly and valve plug in a soft‐jaw chuck or other type of vise so that the jaws grip a portion of the
valve plug that is not a seating surface. Drive out or drill out the pin (key 6, figure 9, 10, or 11. Drive out the pin (key
36, figure 15).
Table 6. Recommended Torque for Fisher ENVIRO‐SEAL Bellows Seal Packing Flange Nuts
VALVE
SIZE,
NPS
VALVE STEM DIAMETER
THROUGH PACKING
MINIMUM TORQUE
MAXIMUM TORQUE
N
S
m
Lbf
S
in
N
S
m
Lbf
S
in
1/2 ‐ 2
1/2
3
24
5
48
3 ‐ 4
1
7
60
10
84
5. Reverse the stem/bellows and plug/adaptor assembly in the soft‐jaw chuck or vise. Grip the flat areas on the valve
stem just below the threads for the actuator/stem connection. Unscrew the plug/adaptor assembly from the
stem/bellows assembly. Unscrew the valve plug from the adaptor.
6. To attach either the existing valve plug or a new one to the stem of the new ENVIRO‐SEAL stem/bellows assembly,
first attach the plug to the adaptor (if the valve plug was removed from the adaptor) as follows:
D
Locate the adaptor. Notice that a hole has not been drilled in the threads where the plug screws onto the adaptor.
D
Secure the valve plug in a soft‐jaw chuck or other type of vise. Do not grip the plug on any seating surface. Position
the plug in the chuck or vise for easy threading of the adaptor.
D
Thread the adaptor into the valve plug and tighten to the appropriate torque value.
7. Complete the installation by following steps 7 through 9 and steps 12 through 15 of the ENVIRO‐SEAL Bellows Seal
Bonnet installation instructions given above.
Purging the ENVIRO‐SEAL Bellows Seal Bonnet
The ENVIRO‐SEAL bellows seal bonnet can be purged or leak tested. Refer to figure 15 for an illustration of an
ENVIRO‐SEAL bellows seal bonnet, and perform the following steps for purging or leak testing.
