Depends, what kind of repairs are we talking about? If you're just changing out a seal you probably don't need any. If you had to weld a crack in the casing I'd look at radiography/UT testing & hydrotesting, if you installed a new impeller I'd think about a performance test, if you installed a new electric motor you'd might be as simple as bump test to make sure it was wired in right, not to mention alignment checks. If it was some modifications done to the rotor of a high speed or multistage pump, you might be looking at vibration & torsional testing again. There's a lot of different tests to be run, really depends on what you did.
You may want to consider conducting a number of dial indicator tests on each rebuild (higher priority if you are running mechanical seals instead of packing.) Try to record the same dial indications while the failed pump is being dissasembled; it should help to determine failure modes if they are not immidiately evident.
-Concentricity of seal gland face
-Stuffing box face perpendicularity
-Shaft run-out (check if shaft is straight and round)
-Radial Deflection (condition of bearings and their fit in housing)
-Shaft end-play
Flowserve has a great form available - Centrifugal Pump Repair Data Form (pg. 229-232 of their Seal Specialist 1 course)
If you are having the impeller rebuilt (either buildup with devcon or trimming), you may want to specify criteria for the rebuild. I dont have any data in front of me, but API might have a balancing specification.
