Sealing Structure Design of High Temperature and High Pressure Eccentric Half Ball Valve

The eccentric half ball valve has the advantages of rapid opening and closing, light weight, small flow resistance, wedge-shaped principle can be used to remove fouling when closing, and is convenient for air control and electric control, etc., and has been widely used in various industries. A new self-sealing structure of the sealing pair is designed for the application of the eccentric half ball valve under high temperature and high pressure conditions.


Working Principle

The center of rotation of the eccentric half ball valve body and the half ball body (that is, the axis of the valve stem) is offset by a radial dimension from the geometric center of the half ball sealing spherical surface, and also has an offset dimension from the sealing surface of the valve seat on the axis of the valve body channel. The eccentric half ball valve relies on two eccentrics to realize self-locking closure, and the reasonable selection of eccentrics makes the self-locking angle smaller than the friction angle. If the self-locking angle is too small, it is easy to close, but it is difficult to open. If the self-locking angle is large, the opening force is small, but the closing torque is increased.


Sealing Structures

1. Seal preload. A certain pre-tightening force is generated by the bolt, and then transmitted to the spring by the valve seat gland, causing the spring to deform. In order to prolong the service life of the spring, the deformation of the spring should not exceed 75% of the free height, and the sealing pair can reach the designed sealing specific pressure through the transmission of a series of forces.

2. The sealing surface has high strength. In order to ensure that the sealing pair is not damaged under high pressure, it is necessary to surfacing hard alloy on the sealing surface of the hemisphere and the valve seat. Surfacing materials need to be adjusted according to working conditions.


The high-temperature and high-pressure eccentric half ball valve adopts a disc spring preloaded self-sealing sealing pair, and the sealing ring material is changed from rubber to V-shaped reinforced flexible graphite or braided flexible graphite ring to achieve reliable sealing of the valve under low pressure. Under the test pressure of 0-10MPa, the opening and closing torque of the valve is small and the sealing effect is good.


Related Products: Eccentric Butterfly Valve

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