The centerline of the pump shaft has to be perfectly aligned with the centerline of the driver shaft (usually an electric motor). If it is not aligned properly you can have problems:
- Extreme heat can be generated in the coupling
- Misalignment can cause severe wear in gear couplings
- Cracked or failed shafts from the constant flexing of the rotating shaft.
- Too much load on the bearings, causing overheating and fatigue problems. Misalignment will cause an un-even face loading with stationary design mechanical seals.
- Excessive axial movement of rotating design seals.
A flexible coupling cannot compensate for pump to driver misalignment. The coupling is used to transmit torque to the pump and to compensate for axial movement of the shaft due to thrusting or thermal growth. Radial misalignment must be corrected by other means.
Prior to doing any type of alignment the pump must be leveled to insure that you have the correct level of oil in the bearings.
There are three popular alignment methods currently being used in industry:
With the reverse indicator method, alignment is done in three stages:
- Determine where the components are located in relationship to each other
- Calculate what has to be moved and how far, to make the centerline of the pump line up with the centerline of the driver. These calculations have to be made at operating temperature.
- Move the hardware, usually the driver
Laser equipment does an excellent job of making the measurements and calculating the amount of movement necessary, but you still have to move the hardware and that is always the most difficult part of alignment because of the lack of jack bolts on the smaller pumps.
All things considered, the C or D frame adapter is the easiest for most people. Many pumps are never aligned because of production’s insistence on getting the pump back on stream as soon as possible.
The “C” or “D” frame adapter lets you do that and still get a good alignment.