Initial alignment Of The Vertical Turbine Pumps (VTP pumps)

A. Thermal expansion

The Vertical Turbine Pump and motor will normally have to be aligned at ambient temperature and should be corrected to allow for thermal expansion at operating temperature. In The Vertical Turbine Pump installations involving high liquid temperatures, the unit should be run at the actual operating temperature, shut down

and the alignment checked immediately.

B. Preparation before alignment

To ensure proper alignment the following items are very important.

a) All machined mating surfaces (such as the mating flanges of pump and motor) must be clean and free of burrs and nicks.

b) Exterior strain must not be transmitted to the pump. The most common cause of trouble is forcing the piping to mate with the pump. It is recommended that flexible connectors be installed in the piping adjacent to the pump.

c) All threads should be checked for damage and repaired if necessary. Lubricate all threaded connections with a suitable thread lubricant (an anti-galling compound).

C. Alignment methods

Ensure pump and driver are isolated electrically and the half couplings are disconnected.

The alignment MUST be checked. Although the Vertical Turbine Pump will have been aligned at the factory it is most likely that this alignment will have been disturbed during transportation or handling. If necessary, align the motor to the Vertical Turbine Pump, not the pump to the motor.

Adding or removing shims between the motor and the discharge head helps alignment in the vertical direction. The motor assembly may also have to be adjusted in the horizontal direction to line up the driver and shaft centers. Alignment screws are provided to lock the motor assembly in its final aligned position.

See final coupling alignment for solid shaft.

Before bumping motor make sure that the coupling halves are not touching and that the driver can rotate freely without rotating the Vertical Turbine Pump. Driver half coupling must be in proper position so the circular key will not come out.

D. Angular and parallel misalignment

Check the direction of pump rotation before the coupling is fully connected. The power supply to the driver to be connected only after the final alignment is complete.

a) Angular Offset: 

The median lines of shaft intersect halfway between the ends of the two shafts.

b) Axial Offset: 

Another offset is the displacement of one or both of the shafts. A typical example is thermal expansion.

c) Parallel Offset: 

The median lines run parallel. The maximum allowable parallel offset depends on the size of coupling and is indicated in the instruction manual of manufacturer of coupling.

For couplings with narrow flanges use a dial indicator as shown in the detail to check both parallel and angular alignment.

a) Vertical Turbine Pumps with thick flanged non-spacer couplings can be aligned by using a straight-edge across the outside diameters of the coupling hubs and measuring the gap between the machined faces using feeler gauges, measuring wedge or calipers.

b) When the electric motor has sleeve bearings, it is necessary to ensure that the motor is aligned to run on its magnetic centerline.

Refer to the motor User Instructions for details. 

A button (screwed into one of the shaft ends) is normally fitted between the motor and pump shaft

ends to fix the axial position.

If the motor does not run in its magnetic center the resultant additional axial force may overload the Vertical Turbine Pump thrust bearing. If the Vertical Turbine Pump is handling hot liquid, the alignment must be rechecked in warm condition of the unit. The alignment of the unit shall be checked again after 200 service hours.