What is the basis for achieving ball valve sealing?

The sealing of ball valves mainly relies on the tight fit between the ball and the valve seat. The sealing principle and implementation method are as follows:

The sealing structure of a ball valve revolves around the design of the fit between the ball and the valve seat. When the ball valve is in the closed state, the through-hole of the ball is perpendicular to the centerline of both ends of the valve body, and the surface of the ball is in close contact with the sealing surface of the valve seat to form a sealing barrier, preventing medium leakage. According to the different sealing materials, ball valves can be divided into two types: hard seals and soft seals. Hard seal ball valves use metal (such as stainless steel, hard alloy) as the sealing surface material, and achieve sealing through mechanical compression or spring loading between metals. They are suitable for high temperature, high pressure, and highly corrosive media environments; Soft sealed ball valves are made of elastic materials such as rubber and polytetrafluoroethylene (PTFE), which use medium pressure to cause elastic deformation of the soft material, thereby tightly adhering to the surface of the ball to form a seal. They perform well under low pressure and room temperature conditions.

The sealing performance of ball valves is affected by multiple factors. The hardness, wear resistance, and corrosion resistance of sealing materials directly affect the sealing life. For example, the surface hardness of metal sealing surfaces needs to be improved through processes such as spraying hard alloys or laser cladding; In terms of processing accuracy, parameters such as sphere roundness and sealing surface roughness need to be strictly controlled, and the sealing surface roughness Ra value is usually required to be ≤ 0.8 μ m; Assembly quality is equally critical, improper control of preload force can lead to excessive wear or leakage of the sealing surface. In addition, the characteristics of the medium (such as corrosiveness, temperature, pressure) and operating conditions (such as opening and closing speed) can also have a significant impact on the sealing effect.

To maintain the sealing performance of the ball valve, it is necessary to regularly check the wear of the sealing surface, clean impurities in a timely manner to prevent scratches, and lubricate moving parts such as the valve stem. Selecting suitable sealing structures and materials for different working conditions, such as using metal hard seal ball valves for high-temperature environments and fluorine or ceramic coating sealing surfaces for corrosive media, can effectively extend the service life of ball valves and ensure sealing reliability.