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........... i__;_]]] rr .... I IHH[H .................... Pump Maintenance

visually inspected for any signs of cracks, surface damage or other
evidence of distress. Particularly take note of erosion, corrosion or wear
patterns.
The pump casing should be examined in the impeller running surface
area, the wear ring area, the volute, the gasket surface and register fit. If
localized wear, pitting or grooving greater than 0.125 inches, deep is
evident, the casing should be replaced or repaired. All alignment and
gasket fits should be inspected for indications of surface damage.
With an open impeller pump, the wear pattern on the contoured
surface of the casing on which the impeller matches should be
considered for indications of shaft deflection or casing misalignment.
In a closed impeller pump, inspect the wear ring locking mechanism for
cracks or other signs of distress. The wear ring(s) should be replaced if
the clearance is greater than 150% of design. Consult the pump supplier
for the wear ring design clearance in that particular service.
The impeller must be inspected for excessive wear, pitting and impact
damage. This is particularly the case on the edges of the vanes of an
open impeller. Any grooving deeper than 0.060 inches, or an even wear
of more than 0.030 inches should require replacement or repair.
Once the visual inspection is complete, it may be appropriate to subject
the casing to non-destruction testing (NTD) procedures to identify any
cracks.
In the event that any weld repair is needed on the casing, it must be
conducted in accordance with the necessary standard and by qualified
personnel, in order to be classified as a long term repair.
When a casing has been damaged by erosion, the casing can be repaired
by applying a coating to reclaim the worn areas. As many aspects of the
coating and it's compatibility to the material are critical in the successful
completion of such a repair, it is recommended that this not be
considered a do-it-yourself job, and a qualified contractor be used. The
chemical compatibility of the coating must also be carefully checked for
compatibility with the process fluid. While the same procedures can be
used against corrosion, it is usually only considered a short term repair.

12.5 Casing and wear rings

The following recommendations and procedures are offered as general
guidelines only for the wet end of the pump. When available, the pump
manufacturer's operation and maintenance instructions are usually the
best source of information for pump assembly.

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