Ruhrpumpen VLT - Alignment

VLT
Vertical Process Pump
34 V1.090418
5.2 ALIGNMENT*
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.
*
Reprinted with permission of Riddle & Hubbel Company, Distributors of Rexnord Products.