- Mechanical damage – e.g. seal face damage due to excessive loads caused by high pressure and damage to faces and other parts caused by incorrect fitting.
- Corrosion and chemical attack – e.g. crevice corrosion or pitting of metal parts due to exposure to excessive levels of chloride, H2S, etc. or cracked or swollen elastomeric o-rings due chemical incompatibility.
- Wear – e.g. accelerated face wear due to abrasives or wear of driving parts such as pins and keyways due to excessive misalignment.
- Thermal overload – e.g. seal rings may develop thermal cracks or blisters due to excessive heat at the seal faces due to poor heat dissipation. Elastomeric o-rings can become hard, brittle and cracked due to excessive heat.