The material of the sealing pair, the quality of the sealing pair, the specific pressure of the seal, and the physical characteristics of the medium are just a few of the many other elements that might affect how well cryogenic ball valves seal. The effectiveness of the valve will be significantly impacted by these variables. Influence. To ensure the valve’s regular operation, it should be designed with the influence of these aspects in mind as much as feasible.

Sealing material

The sealing material’s potential for distortion at low temperatures needs to be taken into account. The metal substance will shrink and deform as the temperature drops, creating a gap at the seal and a drop in the seal’s specific pressure, which will affect the sealing performance. Therefore, it is essential to select a suitable sealing material while developing the sealing structure in order to secure the sealing. In order to reduce friction when a valve is opened and closed and extend the life of the valve, as well as to lower cost and improve sealing performance, the soft sealing method, which combines metal and non-metal materials, is typically used in LNG working conditions.Since polytetrafluoroethylene will produce cold flow at low temperatures, it is not suited for use, while polytrifluorochloroethylene has strong sealing performance regardless of the type of working fluid it is employed in.

Secondary quality of sealing

The sphere’s surface processing quality and the sealing surface’s surface roughness are the major indicators of the sealing pair’s quality. The torque required to open and close the valve can be decreased, the valve’s service life can be extended, and the sealing performance of the valve can be enhanced by making the sphere more rounded and smoothing off its surface. Therefore, it is crucial to enhance the sealing pair’s surface processing quality during design.

Seal specific pressure

The pressure applied to the sealing surface per square inch is known as the sealing specific pressure. The sealing efficiency, dependability, and lifespan of the ball valve are all directly impacted by the size of the sealing specific pressure. However, the valve ball’s sealing specific pressure is not as high as it may be. In some cases, a higher sealing specific pressure is helpful for sealing, but as the sealing specific pressure rises, the torque required to operate the valve will also rise, which is not good for sealing. The valve is operating normally. So, another crucial component of the sealing design of ultra-low temperature ball valves is the choice of sealing specific pressure.

physical properties of the medium

The seal will be affected to some extent by the physical characteristics of the medium, such as its viscosity and temperature. First off, a medium’s penetrability decreases with increasing viscosity, making it harder to leak. Low temperature conditions are when the medium’s temperature has the greatest impact on the seal. Leakage results from the modification of the sealing structure brought on by the sizing change of some sealing components. The seal will be destroyed at the same time as the sealing area’s sealing pressure changes. As a result, the effect of temperature must be taken into account when constructing the sealing structure.