Study on the design of ball valve based on elastic ring valve seat structure and fluid characteristics and fatigue strength

Abstract

Aimed at the technical problems such as the influence of granular medium on spring pre-tightening force sealing, a new ball valve based on elastic ring valve seat structure is studied. The spring plate type valve seat structure is designed to cooperate with the ball core for sealing, and the blade spring coil is used to cooperate with the ball core for sealing in the spring plate type valve seat structure. Wherein the supporting back ring supports the blade leaf spring on the outer side to enhance and protect the role of the blade spring coil. The design without the spring cavity avoids the problem of sealing failure caused by medium entering into the spring cavity and affecting the compression spring, and avoids the situation that the valve seat can be sealed with the ball core by pre-tightening the compression spring, thus avoiding the problem of sealing failure caused by the valve seat sticking on the valve body. The mechanical and flow characteristics are studied and analyzed by the ball valve characteristic test system. The stem torque, unbalance torque, flow characteristics and flow coefficient variation at different nominal diameters are analyzed. The seal allowable squeeze stress and seal surface pressure are analyzed, and the seal is stable and reliable with the seal pressure meeting the seal design criteria. The fluid dynamics simulation analyzes the velocity, pressure and flow traces of the fluid flowing through the ball valve under three opening degrees: fully closed, half open and fully open, the maximum velocity-pressure and opening degree variation curves of the inlet and outlet, the maximum velocity-pressure and opening degree variation curves of the inlet and outlet under different nominal diameters and the flow resistance coefficient curves. Static strength analysis was done for the ball core and spring plate seat structure to obtain the stress, displacement, strain and safety factor. The fatigue strength of the ball spool and spring-loaded plate seat structure was analyzed, and the total number of lives (cycles) and load factors were obtained, and the results show that the fatigue strength of the ball spool and spring-loaded plate seat structure is safe and the fatigue strength meets the requirements. Ball valve pressure test, low pressure sealing test and high pressure sealing test, valve body strength and ball valve sealing performance all meet the requirements.