Instruction Manual

Instruction Manual
D100390X012
ED Valve
October 2014
19
5. After removing the piston ring(s), locate the 1/4-inch diameter hole in the groove. In a retainer with two piston ring
grooves,theholewillbefoundintheuppergroove.
6. Selectanappropriatetoolsuchasapunchandplacethetipofthetoolintotheholewiththebodyofthetoolheld
tangent to the outside diameter of the retainer. Strike the tool with a hammer to rotate the retainer and free it from
thevalveplug.Removetheretainerfromtheplug.
7. Use an appropriate tool such as a flat-blade screwdriver to pry the C-seal plug seal off the plug. Use caution to avoid
scratches or other damage to the sealing surfaces where the C-seal plug seal makes contact with the valve plug
(figure 10).
8. Inspect the lower seating surface where the valve plug contacts the seat ring for wear or damage which would
prevent proper operation of the valve. Also, inspect the upperseatingsurfaceinsidethecagewheretheC-sealplug
seal contacts the cage, and inspect the sealing surface where the C-seal plug seal makes contact with the plug
(figure 10).
9. Replace or repair trim parts according to the following procedure for Lapping Metal Seats, Remachining Metal
Seats, or other valve plug maintenanceproceduresasappropriate.
Lapping Metal Seats (C-seal Constructions)
Before installing a new C-seal plug seal, lap the lower seating surface (valve plug to seat ring, figure 10) following
appropriate procedures in the Lapping Metal Seats section of this manual.
Remachining Metal Seats (C-seal Constructions)
See figure 11. A valve plug with a C-seal metal plug seal features two seating surfaces. One seating surface is found
wherethevalveplugcontactstheseatring. The second seating surface is found where the C-seal plug seal contacts
the upper seating surface in the cage. If you machine the seats on the seat ring and/or plug, you must machine an
equal dimension from the seating area in the cage.
CAUTION
If metal is removed from the seat ring and plug and a corresponding amount is not removed from the cage seating area, the
C-seal plug seal will be crushed as the valve closes and the C-seal retainer will strike the seating area of the cage, preventing
the valve from closing.
Trim Replacement (C-seal Constructions)
1. Apply a suitable high-temperature lubricant to the inside diameter of the C-seal plugseal.Also,lubricatethe
outside diameter of the valve plug where the C-seal plug seal must be pressed into the proper sealing position
(figure 6).
2. Orient the C-seal plug seal for correct sealing action based on the process fluid flow direction through the valve.
D The open interior of the C-seal plug seal must face up in a valve with flow-up construction (figure 6).
D The open interior of the C-seal plug seal must face down in a valve with flow-down construction (figure 6).
Note
An installation tool must be used to properly position the C-seal plug seal on the valve plug. A tool is available as a Fisher spare part
or a tool could be manufactured following the dimensions given in figure 7.
3. PlacetheC-sealplugsealoverthetopofthevalveplugandpressitontotheplugusingtheinstallationtool.
Carefully press the C-seal plug seal onto the plug until the installation tool contacts the horizontal reference surface
of the valve plug (figure 8).