A Fuzzy Decision Support System for Predicting Gasket Constants and Minimum Seating Stress of Polytetrafluoroethylene GYLON® 3504

Abstract

Abstract. This study presents a fuzzy decision support system (FDSS) for predicting leakage behavior and deriving Pressure Vessel Research Council (PVRC) gasket constants and minimum seating stress for polytetrafluoroethylene (PTFE) GYLON® 3504 gaskets using limited modified room-temperature operational tightness (ROTT) test data. A multiple-input, single-output fuzzy inference model was developed from modified ROTT measurements at fixed helium pressures of 200 psig (1.38 MPa) and 800 psig (5.5 MPa), platen surfaces [Ra ≈ 20 μin. (0.5 μm) and Ra ≈ 900 μin. (22.9 μm)], nine gasket stress levels per cycle, and two test cycles representing seating (Cycle A) and operating/unloading (Cycle B). The FDSS maps pressure, roughness, gasket stress, and loading cycle to mass leakage rate within the measured test domain. Missing intermediate Cycle B values were estimated by Lagrange interpolation for rule-based completion. Predicted leakage values were converted to the tightness parameter and used to regress PVRC constants through standard log–log relationships. Results show good agreement for the seating parameters Gb and a, whereas the operating parameter Gs is more sensitive to the limited Cycle B dataset and regression consistency.