Fisher NPS 12 Instruction Manual page 15

Instruction Manual
D103553X012
Secure the seat ring (key 9) with the cap screws (key 49). Tighten the cap screws in a criss-cross pattern to a torque of
39 NSm (29 lbfSft) for NPS 12, 14, and 16 valves.
2. Install a cage gasket (key 11) into the valve. Temporarily install screws or bolts into the tapped holes in the top of
the cage assembly (key 3) to help while installing this piece into the valve. Any rotational orientation of the cage or
assembly with respect to the valve is acceptable.
For ET valves, use care to avoid damaging the seat ring seal ring and cage seating surfaces while handling the heavy
parts. To help insert the cage or assembly into the valve, lubricate the outside diameter of the seat ring seal ring with
lithium grease.
3. Slide the valve plug (key 2) and stem assembly into the cage.
For valves with a seal ring, make sure the valve plug seal ring (key 28) is evenly engaged in the entrance chamfer at the
top of the cage or cage assembly to avoid damaging the ring.
For valves with piston rings, make sure the rings are fully engaged into the piston ring groove and flush with the
outside diameter of the plug.
4. Install the bonnet gasket (key 10).
CAUTION
If the packing is to be reused and was not removed from the bonnet, use care when installing the bonnet to avoid
damaging the packing with the valve stem threads.
5. Mount the bonnet on the valve, and complete assembly according to steps 15 through 19 of the Replacing Packing
section, omitting steps 16 and 17 if new packing is not being installed and being sure to observe the note before
step 15.
Large ET and ED Valves
July 2014
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