Flowserve NAF-Duball ball valves - Manual (Page 7)

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10. Assemble the valve as described in section 9.3.
However, first assess whether the seat rings
should be replaced or whether the seat rings
and ball should be lapped together.
11. If possible, pressure test the valve, and retigthen
the bolted joint as described in section 9.3.
9.9 To inspect and replace the packing of
graphite type
The stuffing box usually requires inspection and
adjustment after the valve has been taken into service.
After a certain period of time in service, it may sometimes
also be necessary to repack the valve.
1. Remove the actuator as described in section 9.7.
2. Remove the nuts (26) and remove the gland
bush (23) and the packing (24).
3. Clean the surfaces of the the shaft, gland bush
(23) and the recess in the valve body.
4. Carefully examine the surface of the shaft which
must be completely free from marks and
scratches.
5. Grease the lower part of the shaft that is in
contact with the bushing (29) and the split ring
(27). Avoid to grease the boxpacking. Use a
suitable grease, such as Molykote Paste U or
Gleitmo 700.
6. Fit new packing (24). Then fit the gland bush
(23) and the nuts (26).
7. Tighten the nuts (26) sufficiently to ensure that
the packing is correctly seated and that it is in
contact with both the shaft and the valve body.
Note: Check the condition of the packing and, after the
valve has been taken into service, retighten the nuts (26),
if necessary.
10. Fitting the Actuator to the Valve
1. Fit the actuator. The actuator may be fitted either
in line with the connected pipes or transversely
to them. For fitting in line with the connected
pipes an intermediary plate is required.
2. Ensure that both the valve and the actuator are in
the closed position before fitting the actuator.
The valve is in the closed position when the
keyway in the stem faces in the direction of flow.
(An actuator which uses compressed air to close
the valve and a return spring to open the valve
should be fitted with the actuator and valve in the
open position.)
3. Before fitting a new actuator, check that the
actuator slides easily onto the stem when the
keys are not fitted. Also check that the keys fit
freely into the keyways in the hollow shaft of the
actuator. Deburr if necessary. Grease the hollow
shaft of the actuator and push it in over the
threaded sleeve. Fit the actuator onto the stem.
Fit the bolts and nuts, and tighten them.
4. Fit and adjust the valve positioner, if any
- Fi 41.82.
5. Check the operation and check that the end stops
have been correctly preset. If necessary, adjust -
but then adjust any limit switches at the same
time.
N.B. The direction of closure must always be
clockwise, as viewed from the actuator.