Review of the development history of mechanical seal industry at home and abroad

Mechanical seals first appeared in the form of patents in the United Kingdom in 1885, and began to be used in practice in the early 20th century. The simple end face mechanical seal solves the problem of shaft sealing in the machine manufacturing industry. Compared with conventional packing seals, mechanical seals have obvious advancements in terms of function and composition principles. However, due to the lack of suitable materials and processing machine tools at that time, although this sealing structure has many advantages, its effectiveness has not been fully utilized, and the application of mechanical seals is not much. It was not until the 1920s that with the emergence of new technologies and new materials, the reliability and life of mechanical seals were improved, coupled with the reduction of manufacturing costs, mechanical seals were gradually used in many refrigeration devices. After the 1930s, mechanical seals began to be used for shaft seals of internal combustion engine water pumps.

After the Second World War, mechanical seals have rapidly gained popularity in the United States. With the development of the petrochemical industry, the application of graphite, ceramic, cemented carbide and other materials in the manufacture of mechanical seal moving and static rings and the improvement of surface roughness control in processing technology, the PV value has reached 15MPa•m/s. In the 1950s, balanced mechanical seals and intermediate ring seals appeared in the mechanical seal structure. The PV value reached 30MPa•m/s, and in 1959 it reached 80MPa•m/s. In the 1960s, due to the requirements of the nuclear energy industry, hydrodynamic seals and hydrostatic seals appeared in the mechanical seal structure, and the PV value rapidly increased to 167MPa•m/s. In the 1970s, due to the special requirements of aerospace and nuclear power, the mechanical seal structure appeared multi-level sealing, silicon carbide and high-quality carbon graphite of different impregnated materials appeared on the material, and the PV value reached 360MPa•m/s. In 1977, due to special needs such as nuclear power, the use of spiral-mechanical seal combination seal, improved intermediate floating ring seal, and floating ring-mechanical seal combination seal, etc., the PV value reached 500MPa•m/s.

In the 1980s, as people's awareness of environmental protection increased, "zero leakage" mechanical seals were developed. Based on the principle of hydrodynamic pressure sealing, the thermohydrodynamic wedge mechanical seal and the upstream pumping mechanical seal were developed. While ensuring the sealing performance, in order to obtain a longer service life, using automatic control theory, people have developed a controllable mechanical seal. In the 1990s, the PV value reached 5,700MPa•m/s. After the 1990s, more and more mechanical seals were used under dry friction, high and low temperature, high pressure, high PV value, and extreme working conditions. Mechanical seal technology has appeared end face modification and modification techniques, such as the use of lasers to cut grooves and perforation on the seal end face, and strive to form a stable gas film and liquid film between the friction pairs; use diamond, diamond-like carbon, high The molecular material forms a coating on the friction pair to solve the problem of end face wear of the friction pair of the mechanical seal and prolong the maintenance cycle of the equipment. At the same time, the mechanical seal industry has successively promulgated standards and requirements related to design, manufacturing, and use. In 1994, the National Petroleum Institute issued the API682 standard, which regulates the selection, design, material selection, testing, manufacturing, installation, and leakage of mechanical seals, and has played a major role in promoting the development of the entire mechanical seal industry.