The Importance of Proper Pump Installation and Alignment

Pump alignment is a critical step in properly installing a pumping system. The process ensures that the shafts of two or more rotating machines are properly aligned. This is important for several reasons:

• To reduce vibration and noise. Misaligned pumps can cause excessive vibration and noise, which can be disruptive. In some cases, vibration can also damage the pump.
• To extend bearing life. Misaligned pumps can cause premature bearing wear, leading to costly repairs or replacements.
• To prevent seal leakage. Misaligned pumps can cause seal damage and leakage, which can contaminate the process fluid and lead to costly downtime.

There are several different methods for aligning pumps. Laser alignment is a common practice but at times a dial indicator is still used. To align a pump using a dial indicator, you need to:

• Disconnect the coupling between the pump and the driver
• Mount the dial indicator(s) on one of the shafts
• Zero the dial indicator
• Turn the other shaft until the dial indicator shows the maximum misalignment. Check this value against the recommended values from the pump manufacturer. Note the shaft position where misalignment occurs to adjust horizontal or vertical alignment (or both).

• Adjust the alignment of the motor until the misalignment is within the acceptable tolerances.

Once the pump is properly aligned, connect the pipe to the pump and recheck the alignment to ensure it is still within acceptable tolerance. If the pump is out of tolerance, the pipe must be modified to reduce the amount of stress applied to the pump casing and the alignment process should be repeated. If the pump operates at high temperature, an initial cold and final hot alignment may have to be completed.

Several factors that can cause pump misalignment, including:

• Improper pump installation. If the pump is not installed correctly, it can become misaligned. This includes improper baseplate installation where it flexes or moves during alignment and installation.
• Pipe improper installation. If the pipe is not installed correctly, it can cause misalignment when connected to the pump casing.
• Excessive vibration can cause the pump to become misaligned over time.
• Thermal expansion. As the pump heats up, the components can expand, causing misalignment. A final hot alignment may have to be performed for high-temperature pumps.
• Mechanical shock, such as severe water hammer, can cause the pump to become misaligned. After severe process upsets, pumps should be checked to ensure alignment.

Lessons Learned

While checking the installation of pumps on a project, we were told that the pump had been aligned and signed off. The contractor executing the work did not have extensive pump installation experience, so we asked to spot-check several pumps. A very quick-and-easy spot check of proper installation for pipe stress is to loosen the bolts on the flanges of the pump when loosened, they should move freely in the mounting holes and no excessive movement of the pipe or pump should be observed. During a check of one of the vertical split-cooling tower pumps, an excessive gap was observed between the 16-inch pipe and the pump flange. When the alignment was rechecked, it was observed to be out of tolerance. An NCR was written, and the realignment and correction of the pipe fit-up were observed. Once the pipe was adjusted and alignment redone, the installation was accepted.

Observations can be made to easily check whether proper installation and alignment steps have been taken. If installation steps are done out of order, this is a clear flag that the complete installation should be checked for compliance.

A second example of lessons is when we observed that the pumps were set in place and connected to the pipe with shipping protection still in place—a clear indication that alignment had not been performed before anchoring the pump or connecting to the pipe system. This was flagged and the installation had to be reversed and then redone, leading to rework and delays for the contractor. While this is the correct course of action, this was not immediately caught. Being actively involved in walking a site and observing the actions of construction engineers can help catch these deviations early and minimize the amount of rework created for a project.

Improper installation is possible, even with pumps that are directly coupled and sealless. Proper installation steps should still be taken and checked.

During the installation of a set of mag drive pumps in acid service, excessive movement of the pump was observed. Closer inspection revealed that the pumps were to have a “floating” installation, meaning they would not be anchored to the concrete—they were literally floating. The CPVC pipe was installed so it supported the pumps off the ground, putting undue stress on the plastic pipe, leading to premature failure. The contractor was forced to redo their work under supervision for a proper installation.

Proper pump alignment is just one part of properly installed pumps. Factory alignment should not be relied upon; field alignment is always required and often needs supervision. It is essential for ensuring the safe and efficient operation of the pumps. All installation practices should be closely followed and checked where possible. Field engineers should be active in observations to assist contractors, and the project, to stay on schedule and avoid costly rework. By following the steps outlined here, you can ensure that your pumps are properly installed and extend the equipment life of installed pumps and components.

REFERENCES

[1] Flowserve Durco Mark 3 ISO pump installation Manual

About the Author

Scott Stellern is an office rotating SME and rotating Protégé in Fluor working out of the Greenville office. Scott holds a Mechanical Engineering degree from Clemson University and is a registered Professional Engineer in South Carolina. Fluor designs and builds projects in the engineering, procurement, and construction industry, executing projects around the world.