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Pump Installation 8 Piping

PI.#1 Pl.~ PI.~ Pt.#4

6.0" J.. 3.9" 12.0"
"-I-" p- -.q ~.-

+31.0
m m
Pump Shaft r-7.0 "~ -"'-
+3.8 mils/"

Poh~t I Offset - Poh~t 2 Offset
SLOPE in mils./inch -
Distance be~ccn points
Figure 10.12: Angular misalignment diagram

and then dividing the result by the axial distance between the two
points. This misalignment should be measured and calculated in both
the vertical and horizontal planes.

10.3.3 High temperature corrections
When a foot mounted process pump is required to operate at elevated
temperatures, some adjustment will be necessary to allow for the
thermal growth that takes place between the cold condition and the
high operating temperatures. As the pump heats up, the shaft ccnterline
will be moved up by the thermal growth of the pump, creating an offset
with the motor shaft.
One method of handling this situation is to misalign the motor by the
amount of growth anticipated from the pump prior to starting the
pump. Most pump manufacturers can provide the cold setting figures
corresponding to the higher operating temperatures. This will require
the pump and motor shafts to run in a misaligned setting until the
pump is fully up to temperature, by which time, the expansion of the
pump will raise the pump into position to align with the motor.
A second method is to start the pump and motor following a cold
alignment without any adjustment. As the pump heats up and expands,
it will gradually move up, out of alignment with the motor. When the
pump is fully up to temperature, the unit is stopped and hot alignment
takes place.

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