Emerson Fisher EHD Instruction Manual page 27

Instruction Manual
D100394X012
3. Place the C‐seal plug seal over the top of the valve plug and press it onto the plug using the installation tool.
Carefully press the C‐seal plug seal onto the plug until the installation tool contacts the horizontal reference surface
of the valve plug (figure 12).
4. Apply a suitable high‐temperature lubricant to the threads on the plug. Then, place the C‐seal retainer onto the
plug and tighten the retainer using an appropriate tool such as a strap wrench.
5. Using an appropriate tool such as a center punch, stake the threads on top of the plug in one place (figure 13) to
secure the C‐seal retainer.
6. Replace the piston ring(s) following instructions in the Trim Replacement section of this manual.
7. Return the seat ring, cage, plug/retainer assembly, and stem to the valve body and completely reassemble the valve
package following the appropriate instructions in the Trim Replacement section of this manual.
CAUTION
To avoid excessive leakage and seat erosion, the valve plug must be initially seated with sufficient force to overcome the
resistance of the C‐seal plug seal and contact the seat ring. You can correctly seat the valve plug by using the same force
calculated for full load when sizing your actuator. With no pressure drop through the valve, this force will adequately drive
the valve plug to the seat ring, thus giving the C‐seal plug seal a predetermined permanent set. Once this is done, the
plug/retainer assembly, the cage, and the seat ring become a matched set.
8. With full actuator force applied and the valve plug fully seated, align the actuator travel indicator scale with the
lower end of valve travel. Refer to the appropriate actuator instruction manual for information on this procedure.
Figure 15. Example of Machining the Lower (Valve Plug to Seat Ring) and Upper (C‐seal Plug Seal to Cage) Seating
Surfaces
NOTE:
REMOVAL OF 0.254 mm (0.010 inch) FROM THE VALVE PLUG
1
REMOVAL OF 0.254 mm (0.010 inch) FROM THE SEAT RING
PLUS
2
MUST EQUAL
3 REMOVAL OF 0.508 mm (0.020 inch) FROM THE
UPPER SEATING SURFACE IN THE CAGE
4. THESE VALUES ARE FOR EXAMPLE ONLY. REMOVE ONLY THE
MINIMUM AMOUNT OF MATERIAL REQUIRED TO REFURBISH THE SEATS.
A6781 / IL
C‐seal
RETAINER
0.508 (0.020)
MACHINING OF THE UPPER
SEATING SURFACE MUST
EQUAL THE TOTAL MACHINING OF
THE LOWER SEATING SURFACE
(PLUG PLUS SEAT RING). IF NOT, THE
RETAINER MAY STRIKE THE UPPER
SEATING SURFACE BEFORE THE
VALVE PLUG PROPERLY SEATS ON
THE LOWER SEATING SURFACE.
PLUG
CAGE
(4)
1 0.254 (0.010)
SEAT
RING
(4)
0.254 (0.010)
LOWER SEATING SURFACE
EH (1-1/2x1 through 8x6)
UPPER SEATING SURFACE
(4) 3
2
mm (inch)
July 2017
27