Pump Alignment

[dross56]

After pump alignment, will torqueing of flanges upstream of the inlet or downstream of the outlet cause stress or shaft misalignment? The pumps in question are in a refinery, various sizes and services.

 

[Scipio]

It's possible, but unlikely unless the piping wasn't properly aligned with the pump, or the torquing was done by a pipefitter weighing in around 300 lbs with a four foot snipe on the torque wrench. I'd do my pipe strain alignments after everything was bolted up anyway, just to be on the safe side.

 

[Kawartha]

dross56,

If you are talking about the pump suction and discharge flanges, the answer is yes. Any significant out of alignment between the pump and piping flanges will be reflected in misalignment of the shaft. The greater the flange loads, the more misalignment. API 610 provides allowable flange loads. Even these limits result in seal misalignment which as I recall is limited (by API 610) to about 0.002" with maximum flange loads.

If you are referring to upstream and downstream flanges, the same maximum allowable flange loadings (at the pump flange) will also apply.