Four Major Reasons for Mechanical Seal Failure

There Are 4 Reansons Bellow

1. Mechanical seal failure can be caused by the loss of lubricating film on both seal end faces. Such leak often results from seal wear, highlighting one cause of mechanical seal leak.

• Due to the presence of end face sealing load, dry friction occurs when the pump is started due to a lack of liquid in the sealing chamber. This can further contribute to mechanical seal leak.
• The medium’s pressure below the saturation vapor pressure causes flash evaporation of the end face liquid film, resulting in loss of lubrication, which is a typical cause of mechanical seal leak.
• If the medium is a volatile product, scaling or blockage in the mechanical seal cooling system increases the saturated vapor pressure due to friction and agitation, leading to pressure below vapor pressure and film loss. This is known to cause mechanical seals to fail.

1. Mechanical Seal Failure Caused by Corrosion

• The sealing surface becomes corroded or even penetrated by external factors, inevitably resulting in mechanical seal leak.
• Tungsten carbide rings and stainless steel seats, due to the inlay process, are prone to intergranular corrosion at inlay positions. This specific type of corrosion can result in leak of the mechanical seal.
• Welded components such as bellows and springs may rupture under stress and corrosive media, leading to mechanical seal failure.

1. Mechanical Seal Failure Caused by High-Temperature Gas Effects

• Hot cracking is common in high-temperature oil pumps due to dry friction, cooling water loss, impurities, and seal evacuation. This causes radial cracks on the ring surface and subsequent mechanical seal failure.
• Graphite carbonization occurs in carbon graphite rings if temperatures exceed tolerance, leading to resin precipitation, foaming, and eventual seal failure. This situation exemplifies mechanical seal leak.
• Auxiliary seals (fluororubber, EPDM, etc.) rapidly age, crack, and lose elasticity when overheated. Flexible graphite resists high temperature but is brittle and damage-prone, causing mechanical seal leak.

1. Sealing Failure Caused by Wear on the Sealing End Face

• Poor wear resistance, high friction, and excessive end face pressure reduce seal lifespan. Wear resistance ranking: silicon carbide > hard alloy > ceramic > sprayed ceramic > silicon nitride ceramic > HSS > welded alloy. Wear often results in mechanical seal failure.
• Media with solid particles cause abrasiveness and wear. Seal clearance, balance, and evaporation affect end face opening and particle intrusion., leading to seal failure.
• The balance degree β affects wear. Typically, β = 75% is ideal. Lower β reduces wear but increases leakage. For high-load seals, β = 65–70%; for low-boiling hydrocarbons, β = 80–85% to limit vaporization effects. Wear and balance are critical factors in preventing mechanical seal leakfailures.