Valve Plug Maintenance - Emerson Fisher ET Instruction Manual

Instruction Manual
D100398X012
Except with respect to the ENVIRO‐SEAL Bellows Seal Bonnet assembly, with metal‐seat constructions, lapping seating
surfaces of the valve plug and seat ring or liner (keys 2 and 9, figure 16, 17, or 20) can improve shutoff. (Deep nicks
should be machined out rather than ground out.) Use a good quality lapping compound of a mixture of 280 to
600‐grit. Apply the compound to the bottom of the valve plug.
Assemble the valve to the extent that the cage and the cage retainer and bonnet spacer (if used) are in place and the
bonnet is bolted to the valve body. A simple handle can be made from a piece of strap iron locked to the valve plug
stem with nuts. Rotate the handle alternately in each direction to lap the seats. After lapping, remove the bonnet and
clean the seat surfaces. Completely assemble as described in the Assembly portion of the Trim Maintenance procedure
and test the valve for shutoff. Repeat the lapping procedure if leakage is still excessive.
Figure 7. Typical Balanced TSO Trim
A7096

Valve Plug Maintenance

Except where indicated, key numbers in this section are referenced in figure 16 for standard NPS 1 through 6
constructions, figure 17 for Whisper Trim III, figures 18 and 19 for WhisperFlo trim, and figure 20 for Cavitrol III detail
and the NPS 8 ET valve.
CAUTION
To avoid the valve plug seal ring (key 28) 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:
VALVE PLUG SEAL
PROTECTED SOFT SEAT
ET Valve
November 2017
13