1. For the design of static sealing system, the sealing products made of plant fiber and asbestos are gradually eliminated, but for the sealing of chemical polymer materials, they are not generally used in some liquid static sealing devices. The current domestically produced hydraulic rubber Seals and anaerobic rubber seals can be used in hydraulic mechanical sealing system equipment. There are few domestic seal brands, and the level of process manufacturing and quality stability are very different from imported seals.

2. For the shaft rotary dynamic sealing system, most of the market still uses ordinary standard oil seals. When the shaft rotary dynamic sealing equipment has pressure design requirements, the pressure level provided by the domestic pressure-resistant oil seal seals is from 1 to 3 Megapascals, while imported seals can provide a pressure level of 10 megapascals, at least more than three times that of domestic products. For dynamic hydraulic pressure oil seals, there is currently no universal application in mechanical shaft rotary seal systems .

Third, for the reciprocating motion sealing system of the hydraulic cylinder, most of the domestic engineering hydraulic machines on the market, and the design of the main seal of the dynamic sealing system of the hydraulic cylinder are generally U-shaped seals. In the engineering hydraulic machinery after the 1990s, the design of the reciprocating dynamic sealing system of the hydraulic cylinder began to use a more complex U-ring and coaxial seal assembly. At present, the more mature designs in the world are 5 combination rings, 4 combination rings, 3 combination rings, 2 combination rings, etc., which are applied to the piston belt support ring of the hydraulic cylinder block. The combination ring is used as a sealing component. It is relatively complicated, and the domestic design and manufacturing capabilities are not yet capable of mass production, and the quality level of the combination ring is still relatively poor.