Lined Ball Valve Sealing Pressure Specificity Analysis

1. Overview
COSMOSWORKS is a design and analysis system fully integrated into SOLIDWORKS. It provides pressure, frequency, constraint, thermal, and optimization analysis, offering designers a comprehensive analytical tool within the SOLIDWORKS environment. This article focuses on the Lined Ball Valve seat. In the valve seat engineering design process, the total force acting on the seat sealing surface and the sealing pressure ratio are calculated using empirical or modified formulas in actual design. These two parameters are difficult to accurately measure using existing methods. By using COSMOSWORKS finite element analysis software to calculate the sealing pressure ratio of a trunnion-mounted ball valve under simulated operating conditions and comparing it with theoretical calculation formulas, this provides a relatively accurate reference for valve design.
2. Solid Modeling
Taking the design of a DN239mm, PN25MPa trunnion-mounted ball valve as an example, the various components of the trunnion-mounted ball valve are first solid modeled in SOLIDWORKS and assembled (Figure 1). Interference checking is performed on the assembly to obtain an assembly with no interference between parts.
3. Finite Element Analysis
3.1. Sealing Mechanism
A fixed ball valve uses an inlet seal. At this time, the ball valve pressure differential (P-P1) is greater than 0 (P and P1 are the fluid pressures in the valve inlet and center chambers). When the pressure differential reaches a certain level, resulting in a certain compression ratio on the sealing surface, this pressure ratio will cause elastic-plastic deformation of the valve seat, filling microscopic irregularities on the sealing surface and preventing fluid from passing through the seal. When the pressure differential is small or the valve seat is made of metal, a complete seal cannot be achieved solely by the pressure differential. In this case, an external sealing force must be applied to increase the compression ratio. The empirical formula for calculating the required sealing pressure qb based on the operating pressure is qb = 1.2PN = 30MPa. To ensure a reliable ball valve seal, a sufficient pressure ratio should exist on the contact surface between the ball and the valve seat, but it must not exceed the allowable pressure ratio [q] of the sealing material.