Instruction Manual
D100386X012
DandDAValves
June 2014
8
Table 5. Torque for Seat Ring (Key 2)
VALVE SIZE, NPS
RECOMMENDED TORQUE
NSm LbfSft
1 407 300
2 698 515
10. Slide the packing follower, upper wiper, and packing flange (keys 10, 21, and 12) into position. Lubricate the
packingflangestuds(key13)andthefacesofthepackingflange nuts (key 15). Install the packing flange nuts.
11. For spring-loaded PTFE V-ring packing, tighten the packing flange nuts (key 15) until the packing follower (key 10)
contacts the bonnet. For other packing arrangements, tighten the packing flange nuts (key 15) alternately in small
equal increments. Continue until one of the nuts reaches the minimum recommended torque shown in table 3.
Then tighten the remaining packing flange nut until the packing flange is level and at a 90-degree angle to the valve
stem.
12. Mount the actuator on the bonnet (key 5) and connect the actuator and valve plug stem according to the
procedure in the appropriate actuator instruction manual.Checkforleakagearoundthe packing follower when you
put the control valve assembly into service. Retighten the packing flange nuts as required.
Trim Maintenance
Refer to figure 4 and 5 for key number locations.
Disassembly
1. Remove the actuator and the bonnet as described in steps 1 through 3 of the Replacing Packing procedure.
CAUTION
Use care to avoid damaging the gasket sealing surfaces.
The stem surface finish of the valve plug/stem assembly (key 4) is critical for making a good packing seal. The seating
surfaces of the seat ring (key 2) and the plug of the valve plug/stem assembly (key 4) are critical for tight shutoff. Protect
these parts from damage if you plan to re-use them in the valve.
2. If you wish, remove the valve plug/stem assembly (key 4)andthepackingpartsfromthebonnet.Ifyouplanto
re-usethevalveplug,tapeorotherwiseprotectthevalveplugseatingsurfaceandthestemthreadstoprevent
damage. Remove the packing parts as described in the Packing Maintenance procedure.
3. Use a socket wrench to remove the seat ring (key 2).
4. Remove the seat ring (key 2) and seat ring gasket (key 3) from the valve body.
5. Inspect parts for wear or damage that would prevent proper operation of the valve body. Clean the gasket surfaces.
6. Replace trim parts as necessary or use the Lapping Metal Seats procedure.
Lapping Metal Seats
A certain amount of leakage should be expected with metal-to-metal seating in any valve body. If the leakage
becomes excessive, however, the condition of the seating surfaces of the valve plug and seat ring (keys 4 and 2, figures
4 and 5) can be improved by lapping. (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.
Partially assemble the valve so the seat ring and valve plug are in place and the bonnet (with bushing installed) is
screwed hand-tight into the body. Make a simple handle from a piece of strap iron locked to the valve plug stem with
(24 strony)
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