Pump Alignment Dilemma
As the owner of a small business, and as a retired construction millwright and industrial mechanic, occasionally I am asked to instruct millwrights in the proper use of alignment lasers and precision ...
December 1, 2008 | By MRO Magazine
As the owner of a small business, and as a retired construction millwright and industrial mechanic, occasionally I am asked to instruct millwrights in the proper use of alignment lasers and precision optical equipment.
On one occasion, a customer, a large Ontario industrial contractor, was installing a line of various size pumps in a new processing plant. I was asked to go over the proper procedures for using an alignment laser with its millwrights.
The pumps and motors to be installed were sent to the site as pre-assembled and pre-aligned, a common practice these days. All that was supposed to be necessary was to hook up the piping and electrical. The contractor wisely decided to have the millwrights use the alignment laser to check the alignment after the pipefitters hooked up the units.
After the initial training session, we took the alignment laser to a completed pump and motor assembly. The millwrights had no problem setting up the laser, but the first readings showed major misalignment.
The millwrights then followed normal procedures to re-align the motor, but found that the unit was in a ‘bolt bound’ scenario, whereby there was absolutely no room to move the motor. To further complicate matters, there was no room to relocate the bolt holes.
Problem: How can this be possible on a pre-assembled and pre-aligned pump-motor assembly?
Solution: I looked down the line and saw pipefitters installing intake pipes on a pump. They were using a chain come-a-long to force the pipe into position! This was the problem.
In forcing the pipe into position to fit the pump, great strain is placed on the pump and pipes, and this in turn often moves the pump and destroys the alignment.
This unfortunately is a common circumstance, simply because engineers, managers, foremen or workers are not knowledgeable about the proper procedures to use.
Also, pipefitters are often required to locate the piping prior to the pumps being installed and occasionally the drawings get changed, so the information is incomplete or simply different.
When installing piping on a pump, the millwright should have two dial indicators on the tail end of the pump to show X and Y deviation. As the pipefitter tightens the bolts, the indicators will show deflection of the pump. If the indicator should move more than 0.005 of an inch (five thousandths), the pipefitter must move to the opposite side of the flange bolt to tighten. This procedure must be followed on both the intake and output of the pump.
This removes the possibility of strain and misalignment and saves large amounts of money for everybody. Mr. O’s thanks for this tip go to Brian Boese of Precision Equipment Rental Inc., which rents Pruftechnik alignment lasers. See www.precisionequipmentrental.com.
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