Spirax Sarco Spira-trol K Series, Installation And Maintenance Instructions Manual

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IM-S24-42 CTLS Issue 10
54
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TRANSLATION RUN OVER
20
3 mm
Fig. 23
11
5.6 Refitting the bonnet
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Fit a new bonnet gasket ( 15 ).
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Using appropriate lifting equipment, carefully lower the bonnet into place over the valve stem. Care must
be taken not to damage the new gland packing at this stage. Note: that the actuator mounting hole
orientation should be in line with the valve flow axis.
-
By hand tightening only, refit the bonnet nuts ( 21 ) to secure the bonnet in place.
-
Raise the plug and stem assembly fully and forcefully push it back into the seat to align the internal
components. Repeat a further two times. Re-tighten all bonnet nuts, hand tight.
-
Apply a load to the stem (preferably replace the actuator), then re-tighten the bonnet nuts in sequence
(see Figure 15 and Table 2).
-
Tighten the bonnet nuts to 30% of required torque setting following a diametrically opposed sequence
(see Figure 15 and Table 2).
-
Repeat the above, using 60% of the required torque.
-
Repeat the above, apply maximum torque value for the appropriate valve size.
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Raise the plug and stem assembly fully and forcefully push it back into the seat, repeat a further two
times.
-
Tighten the gland nut (
11
) until:
i) PTFE gland assembly: metal-to-metal contact with the bonnet is achieved.
ii) Graphite gland assembly: a gap of 3 mm between the underside of the gland nut and the bonnet is
achieved. See Figure 23.
-
Refit the lock-nut ( 20 ).
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Reinstall the actuator.
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Bring the valve back into service.
-
Check for leakage at the gland.
Note: Recheck the graphite seals and retighten the gland if necessary after a few hundred cycles as
the seals fully bed in.