Instruction Manual

Instruction Manual

D100394X012

EH (1-1/2x1 through 8x6)

December 2014

Figure 7. Typical Balanced TSO Trim

VALVE PLUG SEAL

PROTECTED SOFT SEAT

A7096

Valve Plug Maintenance

Key numbers used in this procedure are shown in figure 17 for the EHD valve, in figure 18 for the EHS valve, and in

figure 20 for the EHT valve.

1. With the valve plug (key 3) removed according to the Trim Removal procedure, proceed as appropriate:

For the EHD valve, the piston rings (key 8) are each in two sections; remove the sections from the grooves in the valve

plug.

For the EHS valve, proceed to step 2.

For the EHT valve, work the retaining ring (key 10) off the valve plug with a screwdriver. Carefully slide the backup ring

and seal ring (keys 9 and 8) off the valve plug. For an NPS 6 valve with a level D Whisper Trim III cage, also remove the

piston ring (key 30) from the grooves in the valve plug.

2. Toreplacethevalveplugstem(key4),driveoutthepin(key5),andunscrewthestemfromthevalveplug.

CAUTION

Never reuse an old stem with a new valve plug or reinstall a valve stem after it has been removed. Using an old stem with a

new plug requires drilling a new pin hole in the stem. This weakens the stem and may cause the stem to fail in service. If a

new valve plug is required, always order a valve plug, stem, and pin as an assembly. Specify the correct part number of each

of the three parts, but state that the parts are being ordered as an assembly.

A used valve plug may be reused with a new stem. An exceptionistheCavitrolIIIplug/stem assembly which must be

ordered and replaced as a unit.