Page 104 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Installation, Maintenance, and Repair of Rrtical Pumps 89

Figure 2-13. Greasing a suction bell bearing. (Courtesy Byron Jackson Pump Division,
Borg-Warner Industrial Products, Inc.)

units can be up to two points higher because of reduced disk friction and
more accurate and better finished water passages. The high efficiency
can be sustained by periodic axial adjustment of the rotor without dis-
mantling the pump. Closed impellers are necessary, however, when
pumping hot liquids, because of the axial thermal expansion of the pump,
and generally when the pumps are more than 100 ft in length.

Maintenance and Repair of Wear Rings

Although most users specify wear rings on newly installed pumps, this
is not economically justified as long as the pumps are designed for future
installation of wear rings. When they can be utilized, deepwell turbine
pump components are economical and readily available both as complete
bowl assemblies and as spare parts. Leading manufacturers will furnish
machining dimensions, in a format such as Figure 2-14. When these
pumps require service the impeller wear surfaces can be turned to a pre-
determined diameter and the bowls machined to receive wear rings of
matching dimensions. Original clearance is restored by installing only
one wear ring per stage. These machining and assembly operations are