MECHANICAL SEALS FAILURE,CAUSES AND ITS REMEDIES

On-Site Failure Analysis

• Inspect equipment for excessive shaft movement

– Axial deflection

– Radial deflection

– Run-out

• Inspect seal gland mounting surface to shaft Perpendicularity

• Confirm shaft to box bore Concentricity

Axial Shaft Movement

• Axial shaft movement ( end play ) is usually held within 0.001” to 0.004” T.I.R.

Exceptions: Machines with tilting pad type bearings can have axial thrust

bearing clearance of up 0.020”, machines with tapered roller bearings can

have axial thrust clearance of up to 0.008”

• Measurement usually requires the removal of the seal chamber. Install the dial

indicator support onto the power end portion of the pump, with the dial

indicator pointer against shaft shoulder, adjust to 0. Gently tap the shaft in the

axial axis from the coupled end, then readjust the dial indicator to 0, then

repeat the opposite direction, to obtain total axial end play. Warning:

excessive axial loading on most type of bearings can result in surface

deformation of the bearing races, and possible failure

Handbook Of Heat Exchangers