IM-P150-07
ST Issue 4
10
Note:
Before actioning any maintenance programme observe the 'Safety information' in
Section 1.
Warning
The cover gasket contains a thin stainless steel support ring which may cause physical
injury if not handled and disposed of carefully.
6.1 How to fit the disc:
-
Unscrew the four nuts (
8
) and remove the top cover.
-
Lift off the disc (
2
).
-
Fit a new disc making sure that the body seating surface (
6
) is not unduly worn. If the body
seating surface is only slightly worn it can be refaced by lapping individually on a flat
surface such as a surface plate.
If the wear is too great to be rectified by simple lapping, the seating faces on the body must
be ground flat and then lapped. The total amount of metal removed in this way should not
exceed 0.25 mm.
-
Reassemble the cover using a new gasket (
7
), making sure that the gasket faces are perfectly
clean. Ensure that the name-plate is placed over the studs prior to reassembling nuts.
-
Retighten the cover nuts (
8
) to the recommended tightening torques (see Table 1).
-
After 24 hours in service, and when reassembling, the nuts should be tightened in a diagonally
opposite sequence.
-
Open the isolation valves slowly until normal operating conditions are achieved.
-
Check for leaks.
6.2 How to clean or replace the strainer:
-
Access to the strainer screen can be obtained by undoing the nuts (
8
) and removing the
bottom cover.
-
Remove the strainer screen (
4
).
-
Fit the new or cleaned strainer screen into the recess on the underside of the cover.
-
A new gasket (
7
) should be fitted and the cover refitted.
-
Retighten the cover nuts (
8
) to the recommended tightening torques (see Table 1).
-
After 24 hours in service, and when reassembling, the nuts should be tightened in a diagonally
opposite sequence.
-
Open the isolation valves slowly until normal operating conditions are achieved.
-
Check for leaks.
6.3 To replace the cover studs:
-
After removing the old cover studs, fit new cover studs until the studs bottom out. The use
of a thread lubricant is recommended.
Note:
Two sets of studs are included when the spares are supplied. For traps with flat topped
covers, the long studs should be used. For traps with profiled forged covers, the shorter
studs should be used.
6. Maintenance