When should I perform pump alignment 1

[ghensky]

Is it necessary at all to perform the shaft alignment if only I remove the spool either from the suction or the discharge or both?

I need to disconnect the pumps from the piping by removing the discharge spools and jacking up the suction line without actually touching/moving the volute or motor. I don't see any reason why I need to perform shaft/motor-pump alignment. Couldn't find any reliable resource to backup my gut feelings, hence this post. Thanks for any feedback.

 

[Artisi]

YES,alignment is necessary.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[jari001]

When in doubt, assume the alignment is out.

 

[MikeHalloran]

At least >check< the alignment while you have the pump down and the skilled labor available.


Mike Halloran
Pembroke Pines, FL, USA

 

[ghensky]

Thanks to all for feedback. Once the spool is connected back, I'd ask to check the shaft alignment test, if it passes, I'd give it a go, else perform alignment.

 

[Artisi]

Good idea, coupling mis-alignment is one of the most overlooked but very important aspects for trouble free pump operations and should form part of regular maintenance checks, either by physical checking or by vibration analysis.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[CouplingGuru]

Depending on the type of coupling, alignment checks can be quite easy. If you have a spacer style coupling taking a width measurement across the flex element at 90 degree intervals. This measurement will give you a very clear picture on how aligned the system is. Obviously the more aligned the system is the better it will perform. But I firmly believe that it is process of diminishing returns. A proper system design with an adequate distance between shaft ends can greatly increase the tolerance of alignment accuracy. For instance consider two identical couplings, one connecting two shafts that only are 2" apart from one another compared to another connecting two shafts 6" apart. The coupling connecting the the shafts 2" apart requires 300% greater alignment accuracy to achieve the same restoring force as the coupling connecting the shafts 6" apart. To equate that to real world values, typically we like to see no more than 0.25 degrees at install per flex plane. Assuming perfect angular alignment at 2" shaft spacing that would be 0.0087" parallel misalignment. At the 6" spacing it would allow for 0.0262" of parallel misalignment. That could drastically lower alignment costs and prevent you from trying to avoid the procedure.

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