Finite Element Analysis And Optimization Of Lined Ball Valve Structure

The sealing surface of a Lined Ball Valve has a high hardness, capable of withstanding high operating temperatures and pipeline pressures. It offers excellent throttling and regulation performance, resists damage from solid particles, cavitation, and flash evaporation, and exhibits excellent sealing and wear resistance. It is widely used in coal chemical, polysilicon, oil refining, offshore platforms, and power plants. Metal-hard-seal ball valves are the preferred valve type for applications requiring tight shutoff, high temperatures and high pressure differentials, rapid switching, and media containing solid particles. Currently, hard-seal trunnion-mounted ball valves often experience sealing surface failure and leakage, stem fatigue wear, ball extrusion deformation, or ball coating damage. Theoretical design analysis of these valves has primarily focused on the optimized design of theoretical structures or the analysis of individual components. Component contact analysis, which is most likely to lead to local component failure, and the relationship between design dimensions and contact stresses are less explored. Therefore, in view of the above situation, this paper takes the three-piece hard-seal fixed ball valve produced by Fangzheng Valve Group as the research object, combines the nonlinear contact theory, and uses the numerical simulation method to conduct the following research and analysis on the contact components between the valve stem and the ball, and between the valve seat and the ball: 1. Taking the NPS 12 and CLASS600 hard-seal fixed ball valve as the research object, the Pro/E software is used to establish the three-dimensional model of each component and the assembly model of the hard-seal fixed ball valve, and the ANSYS software is used to simulate the contact components. Workbench software performs nonlinear contact analysis on the commonly used contact parts between the ball and the valve stem; 2. Three ball and valve stem contact optimization schemes are proposed, and models are established and loaded for analysis respectively to determine the maximum contact stress under different structures, and the most suitable scheme is selected by comparison; 3. For the selected optimal scheme, the maximum contact stress is used as the target parameter and the size of the contact part between the ball and the valve stem is used as the design variable, and a relevant sensitivity analysis is performed on it; 4. A nonlinear contact analysis is performed on the contact part between the valve seat and the ball, and the change law of the contact stress and maximum displacement deformation between the valve seat and the ball with the change of the opening is obtained; the equivalent stress and displacement deformation at the opening of 50% and the maximum stress opening are analyzed, and the valve seat with deflection and without deflection are compared, and the stress distribution law on the contact between the deflected valve seat and the ball at the maximum stress opening is analyzed; 5. The influence of the valve seat sealing surface width and the valve seat deflection angle on the maximum equivalent stress and maximum displacement deformation on the valve seat sealing surface is analyzed; the size of the valve seat and the ball contact part is improved to reduce the contact stress and meet the use requirements.