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The following tips are presented for consideration for when “the going gets tough”, meaning that problems like residual soft foot or “bad geometry” or becoming bolt-bound impede your ability to easily obtain an excellent alignment. First, a few definitions:

  • Residual Soft Foot present: A bit more soft foot than you are comfortable with, but that you can’t do anything about, perhaps from slightly angled feet or a bit of pipe strain. Learn about our Rotalign ULTRA Soft Foot Wizard.
  • Bad geometry: Equipment whose distance from – coupling center to front foot- is equal to or greater than the distance from front foot to back foot.
  • Becoming bolt-bound or base-bound: You must still move a little but have run out of room in the anchor bolt holes in the feet, or must still come down a bit but have no shims left under the feet to remove. Learn about our Rotalign ULTRA Move Simulator.

Final Vertical Misalignment Correction (Horizontal Misalignment already “close”)
1. Get front feet position close to offset tolerance. Finish the alignment by correcting the rear feet only.
2. Final feet position should make offset at the coupling center decrease. To achieve this:
Front feet position 
Positive 
Negative 
Examples: 

-2
Back feet position
More Positive
More Negative
Examples: 
4
-3 etc.
3. It is bad to leave feet positions with opposite signs, even if the values are very small.
Examples:
Front feet position


-2 
Back feet position
-1
-2
1 etc.
4. It is bad to leave the value of the front feet position higher than the backfeet position even if they have the same sign.
  
Examples:
Front feet position

-2 
Back feet position
1
-1 etc.
Final Horizontal Misalignment Correction (After vertical is within tolerance)
The above rules apply for the Horizontal corrections also.  For small equipment remember to torque in steps.

Filed under:
, by Pedro Casanova CRL