Mechanical seal failure is commonly related to insufficient lubrication, corrosion, high temperature, and seal face wear. First, when the seal faces lose the lubricating film, dry friction can easily occur. For example, starting equipment without sufficient liquid in the seal chamber, or when the medium pressure falls below its saturated vapor pressure, may cause flashing of the liquid film and loss of lubrication. In addition, scaling or blockage in the cooling system can increase the medium temperature, resulting in vaporization of the liquid film and seal failure.
Corrosion is also a major cause of mechanical seal failure. Seal faces may suffer from pitting or even perforation. Intergranular corrosion can occur at inserted structures such as tungsten carbide rings and stainless-steel holders. Metal bellows and springs may also crack or break under the combined effects of stress and corrosive media.
High temperature can further reduce seal reliability. Under high-temperature conditions, dry friction, cooling interruption, or contaminants entering the seal faces may lead to thermal cracking. Carbon graphite rings may experience resin carbonization when the operating temperature exceeds the allowable limit, resulting in reduced sealing performance. Meanwhile, secondary seals may rapidly age, harden, or lose elasticity at elevated temperatures, causing leakage.
In addition, seal face wear is another important factor affecting seal life. Poor wear resistance of materials, excessive friction coefficient, and improper face pressure can all shorten service life. For media containing solid particles, particles entering the seal faces can cause severe abrasive wear. Furthermore, the balance ratio of a mechanical seal also affects wear and leakage performance. For high-load or low-boiling-point media, selecting a suitable balance ratio is essential to improve sealing stability and service life.