To determine the cause of mechanical seal failure, it is first necessary to draw up an exact damage record. Fringe conditions such as the machine's mode of operation (intermittent mode, cyclic processing sequence), arrangement of supplementary and auxiliary equipment (accessories), effects of extreme climatic conditions and so on must be taken into account when assessing the damage.

Causes of damage:

• Chemical factors :
  corrosion, swelling of O-rings

• Mechanical factors :
  deposits, wear abrasion on O-rings, deflection on the torque transmission pin, erosion (abrasive jet wear), explosive decompression
  extrusion of secondary seals, torsion, wear, distortion of O-rings, warping, shaft wear

• Thermal factors :
  deposits, blistering, thermal shock, dry running, embrittlement of O-rings, warping, thermal stress cracks

• Other factors :
  material errors, production errors, assembly errors