Selection and Material of Mechanical seal

In numerous industrial fields such as petroleum, chemical industry, and others, the working environment of pumps is exceptionally complex, including conditions of high speed, high pressure, high temperature, strong corrosion, high precision, and the presence of solid particles. To ensure safe, stable, long-term, fully loaded, and high-quality production, selecting suitable material of mechanical seal is crucial. Besides carefully choosing the seal structure and system, the selection of material of mechanical seal is equally important. This requires us to carefully select the materials for the seal faces, auxiliary sealing rings, spring elements, and other components based on specific applications, medium characteristics, and working environments. This precise selection is decisive in ensuring the stable operation of mechanical seals, extending service life, and reducing costs.

Selection and Material of Mechnical Seal

Mechanical seal materials, including the end face materials of the rotating ring and stationary ring, are the core of mechanical seal performance. Statistics show that 80% to 95% of mechanical seal leakage problems are related to the material of mechanical seal. Therefore, ensuring the parallelism of the sealing surfaces and choosing the correct materials are key to ensuring the long-term stable operation of mechanical seals.

Necessary Conditions for Material of Mechanical Seal

Qualified mechanical seal materials should possess the following characteristics: high mechanical strength to withstand pressure and deformation; good dry wear resistance and high load capacity with excellent self-lubricating properties; good compatibility with matching materials to avoid excessive wear and reciprocal corrosion; strong wear resistance for long life; excellent thermal conductivity and heat dissipation performance; high-temperature resistance and thermal crack resistance; corrosion resistance and impact resistance; low coefficient of linear expansion, resistance to thermal deformation, and good dimensional stability; ease of machining and forming; good airtightness and low density.

Classification of Mechanical Seals

According to different lubrication methods of the sealing surfaces, mechanical seals can be divided into four categories: traditional contact mechanical seals, which rely on the process fluid to lubricate the sealing surfaces; mechanical seals that use a flushing fluid separated during the process for cooling and lubrication; dry-running mechanical seals that depend on the self-lubricating properties of the material of mechanical seal ; and mechanical seals that rely on externally introduced gas to lubricate the sealing surfaces.

In most cases, for general media, we use a combination of soft to hard mechanical seal materials. Soft mechanical seal materials maintain through the wear and self-lubricating nature of the bearing table, while hard mechanical seal materials rely on the high precision of the wear-resistant table. For impregnated resin or metal graphite materials with excellent thermal conductivity and self-lubrication, they should be given priority. For strongly oxidizing media, ceramic materials are the first choice; for strongly corrosive media, filled PTFE is the ideal choice. Only when handling special media containing hard solid particles do we adopt the hard-to-hard mechanical seal materials combination, such as tungsten carbide to tungsten carbide.