Instruction Manual

Instruction Manual

D100390X012

ED Valve

October 2014

Valve Plug M aintenance

Except where indicated, key numbers in this section are referenced in figure 19 for standard NPS 1 through 6

constructions, figure 20 for Whisper Trim III detail, figure 21 for the NPS 8 ED valve, and figures 22 and 23 for

WhisperFlo trim. Some valve plug constructions require three piston rings (key 6).

CAUTION

To avoid the piston ring (key 6) not sealing properly, be careful not to scratch the surfaces of the ring groove in the valve

plug or any of the surfaces of the replacement ring.

1. With the valve plug (key 2) removed according to the Disassembly portion of the Trim Maintenance procedure,

proceed as appropriate:

For the carbon-filled PTFE piston ring, The ring is split in one place. If there is visible damage, spread the ring slightly

and remove it from the groove in the v alve plug.

To install a carbon-filled PTFE piston ring, Spread the ring apart slightly at the split and install it over the stem and into

thegrooveinthevalveplug.Theopensidemustfacealongthe stem, depending on flow directions, as shown in view

Aoffigure19.

For the graphite piston ring, The ring can be easily removed since it is in two pieces. A new graphite piston ring is

furnished as a complete ring. Use a vise with smooth or taped jaws to break this replacement ring into halves. Place the

new ring in the vise so that the jaws will compress the ring into an oval. Slowly compress the ring until it snaps on both

sides. If one side snaps first, do not try to tear or cut the other side. Instead, keep compressing the ring until the other

side snaps. Be sure to match the broken ends when installing the ring in the valve plug groove.

CAUTION

Never reuse an old stem or adaptor with a new valve plug. Using an old stem or adaptor with a new plug requires drilling a

new pin hole in the stem (or adaptor in case an ENVIRO-SEAL bellows seal bonnet is being used). This drilling weakens the

stem or adaptor and may cause failure in service. However, a used valve plug may be reused with a new stem or adaptor.

Note

For plain bonnets and style 1 extension bonnets, the valve plug (key 2), valve stem (key 7), and pin (key 8) are available completely

assembled. Refer to the Key 2, 7, and 8 Valve Plug and Stem Assembly tables in the Parts List.

2. Toreplacethevalvestem(key7),driveoutthepin(key8).Unscrewthevalveplugfromthestemoradaptor.

3. To replace the adaptor (key 24, figure 18) on ENVIRO-SEAL bellows seal bonnets, place the plug stem 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 the pin (key 36, figure 18). Reverse the plug stem assembly and valve plug 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 valve plug/adaptor assembly (key 24, figure 18) from the valve stem assembly (key 20, figure 18).

4. Screw the new stem or adaptor into the valve plug. Tighten to the torque value given in table 5. Refer to table 5 to

select the proper drill size. Drill through the stem or adaptor, using the hole in the valve plug as a guide. Remove

any chips or burrs and drive in a new pin to lock the assembly.

5. For ENVIRO-SEAL bellows seal bonnets, grip the flats of the stem extending out of the top of the bellows shroud

with a soft-jaw chuck or other type of vise. Screw the valve plug/adaptor assembly onto the valve stem. Tighten as