Lapping Metal Seats (Bore Seal Constructions); Remachining Metal Seats (Bore Seal Constructions) - Fisher EHD Instruction Manual

EH Valves (NPS 8 through 14)
DEFORM THREAD TO
STAKE Bore Seal RETAINER
PISTON
RING
RETAINER
Bore Seal
METAL
PLUG
SEAL
FLOW DOWN
A6779 / IL
Figure 7. Stake the Threads of the Bore Seal Retainer
Use a drill with a 1/8 inch bit to drill out the staked
area of the thread. Drill approximately 1/8 inch into
the metal to remove the staking.
4. Locate the break between sections of the piston
ring(s). Using an appropriate tool such as a
flat-blade screwdriver, carefully pry out the piston
ring(s) from the groove(s) in the Bore Seal retainer.
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, the hole will be
found in the upper groove.
6. Select an appropriate tool such as a punch and
place the tip of the tool into the hole with the body of
the tool held tangent to the outside diameter of the
retainer. Strike the tool with a hammer to rotate the
retainer and free it from the valve plug. Remove the
retainer from the plug.
7. Use an appropriate tool such as a flat-blade
screwdriver to pry the Bore Seal plug seal off the
plug. Use caution to avoid scratches or other
damage to the sealing surfaces where the Bore Seal
plug seal makes contact with the valve plug
(figure 9).
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 Bore Seal plug seal contacts the
16
INSTALLATION
TOOL
Bore Seal
METAL
PLUG
SEAL
VALVE
PLUG
A6778 / IL
NOTE: PRESS THE INSTALLATION TOOL OVER THE VALVE PLUG UNTIL THE
TOOL CONTACTS THE HORIZONTAL REFERENCE SURFACE OF THE VALVE
PLUG.
cage, and inspect the sealing surface where the
Bore Seal plug seal makes contact with the plug
(figure 9).
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
(Bore Seal Constructions)
Before installing a new Bore Seal plug seal, lap the
lower seating surface (valve plug to seat ring,
figure 9) following appropriate procedures in the
Lapping Seats section of this manual.
Remachining Metal Seats
(Bore Seal Constructions)
A valve plug with a Bore 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 Bore
Seal plug seal contacts the upper seating surface in
the cage. The cage does not require any machining,
even when the plug and / or seat ring have been
machined.
Instruction Manual
FLOW DOWN
Figure 8. Installing the Bore Seal Plug Seal
Using the Installation Tool
April 2009
VALVE
PLUG
HORIZONTAL
REFERENCE
SURFACE