Page 177 - Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

Fiaure 11-2

direct and indirect associated costs of its failure and replacement can be
substantial. For example, a pump bearing may only cost $20.00 to buy,
but its failure could also take out a mechanical seal. Now, besides the
cost of the bearing and mechanical seal, is the cost of disassembly and
reassembly of the pump. And, there will be other replacement parts to
change although they may or may not have failed. Some of these would
be the casing gaskets, pipe flange gaskets, set screws, snap rings, clip
rings, wear bands, shims, oil seals, nuts and bolts, not to mention the
oil or grease lost. Then there is the time dedicated to the repair, which
is also the time lost from production.
Most often, the bearing or the lubricant is blamed for the failure. This
is like blaming the hse for an electrical failure. The failure is most likely
a result of some abnormal operating condition, or lack of proper
maintenance. In short, something causes the bearing to fail
prematurely.
Among the most common causes of premature bearing failure are the
following:
1. Improper mounting.
Improper procedure when mounting the bearing on the shaft is one
of the most common causes of premature failure. Roller bearings
and ball bearings are precision devices, and correct installation

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