Effect of Butterfly Valve Disc Shape Variations on （蝶阀阀瓣形状变化的影响）.pdfVIP

Effect of Butterfly Valve Disc Shape Variations on Torque Requirements for Power Plant Applications M. S. Kalsi, B. Eldiwany, Vinod Sharma, Aaron Richie Kalsi Engineering, Inc. ABSTRACT Tests performed by the U.S. NRC/INEL under the “Containment Purge and Vent Valve Test Program” in 1985 showed that manufacturers methods for predicting torque requirements had serious limitations. Under design basis conditions, torque requirements in single-offset valves with shaft downstream were found to be self-opening, instead of self-closing as predicted by valve manufacturers. It was also found that variations in butterfly disc shapes are quite large and the influence of disc shape, upstream piping configuration, ∆P and unchoked vs. choked flow conditions on torque requirements in compressible and incompressible flows had not been adequately addressed by the industry. EPRI, under its MOV Performance Prediction Program (1990-1994), developed analytical models and conducted tests to address some of these shortcomings. However, the models were based on simple analytical approaches with large conservatism to cover known uncertainties, and testing was limited to incompressible flow with only symmetrical and single-offset disc geometries. Furthermore, the EPRI methodology was developed for MOVs, which have a constant actuator output torque capability, and therefore, did require position dependent accuracy in torque predictions for margin evaluation. Torque prediction methodologies for AOVs need to have position dependent accuracy because AOV actuator output varies with stroke. Consequently, the MOV