Shaft deflection. The problems it causes


Excessive shaft deflection can cause a lot of problems including:

  • Opening up the mechanical seal faces when the rotating portion of the seal contacts a stationary component.
  • Overloading of the bearings, especially the radial bearing.
  • A change in the seal face loading
  • A change in the flow direction of a dual seal convection tank.
  • Damage to the impeller and volute.
  • Excessive wear ring wear and loss of pump efficiency as the gap increases. This is a major concern with “vertical, in line” designs.
  • Excessive shaft fretting (wear and damage) at the bearing seal locations.
  • Damage to the bearing seals.
  • Packing sleeve wear.
  • Excessive packing leakage.
  • Overheating of the packing.
  • Damage to the stuffing box throat bushing.
  • Damage to an API (American Petroleum Institute) gland disaster bushing.
  • The breaking of a stationary seal face.
  • Axial movement can change the seal face loading
  • Impeller clearance will be altered. In some cases the impeller could contact the volute or pump back plate.


  • On February 17, 2018