DESIGN AND STRUCTURAL EVALUATION OF A LARGE-DIAMETER BUTTERFLY VALVE USING ELASTIC STRESS ANALYSIS

Abstract

This study presents the design, structural analysis, and validation of a large-diameter butterfly valve in accordance with ASME and MSS standards. The valve body wall thickness was determined using ASME B16.34 Mandatory Appendix VI and MSS SP-67, with corrosion allowances included, resulting in an effective thickness of 21.58 mm. The flange body was designed following ASME B16.47 requirements, while empirical equations were applied for body neck dimensions to ensure load-carrying capacity. The disc was designed with an elliptical profile to minimize deformation, with a final thickness of 80–180 mm to withstand pressure loading. The stem and pin were dimensioned using torque-based design equations, resulting in a stem diameter of 100 mm. A detailed 3D CAD model was developed and meshed for finite element analysis (FEA) to evaluate deformation and stress distribution. Maximum deformation of 3.54 mm occurred at the disc under a pressure of 2.94 MPa, while the body remained structurally stable due to sufficient thickness. Stress classification lines (SCL) were used to linearize equivalent stresses, with primary membrane and bending stresses evaluated against ASME Section VIII, Division 2 criteria. Results indicated that the valve design is safe up to 1.96 MPa, while operation at 2.94 MPa may lead to stress levels exceeding allowable limits. Overall, the proposed design demonstrates compliance with ASME code requirements under the recommended pressure range and provides a safe and efficient structural configuration for large butterfly valves.