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Note: Before actioning any maintenance programme observe the 'Safety information' in Section 1.
6.1 General information
As with all mechanical devices, regular maintenance is the most efficient means of ensuring continued
operational efficiency.
Regular scheduled inspection of all valves is essential, especially on valves which are operated only
occasionally.
6.2 General maintenance
Isolate the unit - Before removing the M33 ISO ball valve from the pipeline to action any maintenance work,
isolate it both upstream and downstream and wait for the unit to reach ambient temperature before handling.
The complete body assembly can then be removed and any new parts fitted - See Section 7.
6.3 How to replace the stem seats:
-
Remove the ball valve from the pipeline observing the 'Safety information' in Section 1.
Warning: Isolate the ball valve both upstream and downstream and wait for the unit to reach ambient
temperature before handling.
-
Remove the nuts (20) from the studs (19) and split the main body (1) from the insert (2).
-
Remove the seats (4) and the ball (3).
-
Withdraw the stem (6) and replace the lower stem seal (7) and the 'O' ring (8).
-
Reassemble the unit using a new body gasket (5). The nuts and studs (19, 20) and gland nut (13) should
be tightened to the recommended torque, see Table 1, page 12.
Please note - When the seats and lower stem seal have been replaced and the valve has been reassembled
it is advisable to conduct a cold hydraulic test to the valve body as follows:
-
ASME 150
28.5 bar g
-
ASME 300
76.5 bar g
It is also advisable to conduct a seat leakage test using compressed air at 7 bar g (101 psi g).
After 24 hours in service, retighten nuts (20 and 13) and check for leaks.
10
6. Maintenance
(410 psi g)
(1010 psi g)
IM-P133-65 CMGT Issue 2
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