J Line Pump
Horizontal Double Suction Centrifugal Pump – API 610 Process Pump
29 V1.032818
In the following pages, alignment procedures are explained with dial indicators. Laser alignment is also
possible. The specific method in laser alignment will depend on the manufacturer’s instructions;
however, the basic principles and rotation of the shafts apply, as in the Reverse Indicator Alignment
Method. Therefore, for laser alignment, you may follow the steps detailed on the next pages, mounting
a laser bracket with a measurement device on each shaft and then proceed with the rotation of the
shafts to obtain the readings to determine the misalignment and correct it.
A. ALIGNMENT OF EQUIPMENT
Correct alignment is mandatory for the successful operation of rotating equipment. A flexible coupling is
no excuse for misalignment. The relationship between shaft centerlines can easily be determined by 1)
two step dial indicator method, 2) reverse indicator alignment, 3) across the disc pack alignment. These
can all be solved by a graphical approach. This procedure will discuss methods 2 and 3. Method 1 is
covered in Rexnord's Manual MT-SS-04-001, "Two Step Dial Indicator Method". Before we get into this
alignment procedure, several items should be considered at this point.
1. Indicator Set-Up
No matter what arrangement you use, indicator sag must be determined. This can easily be determined
by clamping the set-up onto a rigid piece of pipe, rolling the indicator from top to bottom, and reading
the difference. Once the indicator sag set-up has been determined, this number can be algebraically
subtracted from the alignment readings obtain at the bottom. There is no need to be concerned about
the side to side readings as the sag is equal on both sides.
2. Taking Alignment Readings
It is suggested that the dial indicator be zeroed at the top. For convenience, you should mark your
coupling at 0°, 90°, 180°, and 270° with a reference mark on the case so that you can be sure to turn the
unit exactly 90°. Both shafts should be turned an equal amount if the coupling is not put together. Now
rotate the coupling in 90° increments recording all readings. It is important to keep your side to side
readings straight. A suggestion is to show compass orientation so that you know which reading to use.
After you have made your four position check and have returned back to the top, it is absolutely
necessary that the indicator return to zero where it started. If it did not, repeat your readings. It is also
advisable to check the readings several times to make sure that they are repeatable.
3. Thermal Growth
If there are thermal growth considerations on the piece of equipment, it is a good idea to get these
numbers so that they can be added to or subtracted from the graphical solution before the equipment
move is made, this is known as “Hot alignment”.