Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

Alignment 507
bearing motors because they have an elastic centering characteristic that
Is easy to apply to end float limitation and geometric centering of the motor
rotating element.
Alignment Access. As in many fields, forethought is helpful when it
comes to alignment access. A common problem, easily avoided in the
specifying stage, is insufficient exposed shaft between front of bearing
housing and back of coupling for concealed hub couplings. At least one
inch of exposed shaft is desirable to allow alignment bracket attachment.
It is helpful to visualize the radial space requirements of alignment brackets
for full shaft rotation and to avoid placing piping or other interferences
in this circular path. Access for moving and monitoring moves on
the machine element to be adjusted for alignment (usually the driver)
should also be considered. As mentioned earlier, a 2-inch vertical jacking
access beneath each end of a motor will allow insertion of hydraulic jacks
or alignment positioners [9]. Access to install and remove shims and
place horizontal move monitoring dial indicators is also important. Access
for applying and turning wrenches on hold-down bolts should not be
overlooked. Aligning a machine that has one side immediately adjacent
to a wall, or blocked by a maze of pipes, can require acrobatic maneuvers
with a degree of difficulty directly proportional to the age, size, weight,
and arthritic tendencies of the aligner.
Pre-Alignment Steps
It may seem to some readers that we are taking a long time to get into
the ostensible subject—shaft/coupling alignment. This may be true, but
there is good reason for it. One thing builds upon another. Without certain
prealignment steps, the alignment itself is likely to be dangerous, difficult,
or ineffective. Nobody knows exactly how the pyramids were
built, but it is a pretty sure bet that they were not done from the top down.
Pre-alignment steps will now be described.
Work Permit and Power Lockout. This is basic and is usually the first
step. It is essential that all concerned agree on which pump/driver combination
is to be aligned, and that it will be effectively prevented from
starting under power during the alignment.
Personnel Coordination. Sometimes the work area is crowded, and several
categories of work are to be done. Alignment is the type of work that
suffers if non-alignment personnel, such as electricians and pipefitters,
are doing their own jobs in the same vicinity and inadvertently lean
against a jacked-up machine, kick a foot-move-monitoring dial indicator.