Lapping Metal Seats (C-Seal Constructions); Remachining Metal Seats (C-Seal Constructions) - Emerson Fisher EWD Instruction Manual

Instruction Manual
D100399X012
Figure 13. Lower (Valve Plug to Seat Ring) and Upper (C‐seal Plug Seal to Cage) Seating Surfaces
NOTE:
UPPER SEATING SURFACE IS THE AREA OF CONTACT BETWEEN
1
THE C‐seal METAL PLUG SEAL AND THE CAGE.
A6780
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 upper seating surface inside the cage where the C‐seal plug
seal contacts the cage, and inspect the sealing surface where the C‐seal plug seal makes contact with the plug
(figure 13).
9. Replace or repair trim parts according to the following procedure for lapping metal seats, remachining metal seats,
or other valve plug maintenance procedures as appropriate.
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 13) following appropriate procedures in the Lapping Metal Seats section of this manual.
Remachining Metal Seats (C‐seal Constructions)
See figure 14. A valve plug with a C‐seal metal plug seal features two seating surfaces. One seating surface is found
where the valve plug contacts the seat ring. 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.
RETAINER
C‐seal METAL
PLUG SEAL
VALVE PLUG
UPPER SEATING SURFACE
CAGE
PLUG
SEAT
RING
LOWER SEATING SURFACE
1
CAGE
EW Valve
July 2017
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