Study on the sealing performance of high-pressure flanges by a magnetic measurement method of bolt axial force

Abstract

Under high-pressure conditions, flange sealing often fails due to inadequate bolt pre-tension, leading to unstable pressurization or leakage. Assessing the integrity of high-pressure flange sealing presents challenges, constrained by operational conditions, complex equipment integration, and associated costs. This study introduces a method to evaluate flange sealing using magnetic measurements of bolt axial forces. A novel device developed using the magnetoelastic method efficiently and conveniently measures these forces under various internal pressures. The results show a linear relationship between magnetic signals and bolt axial forces at nominal pressures, whereas excessively high pressures cause anomalous changes in magnetic signals, indicative of bolt plastic deformation. Finite element simulation analyzed the changes in bolt axial force and gasket contact stress due to internal pressures, leading to an empirical formula that correlates these variables under varying pressures. The study also explored the impact of uneven pre-tensioning and gasket material on sealing contact stress. A sealing contact surface model, established based on actual roughness profile parameters, enabled the simulation and formulation of an exponential relationship between contact stress and sealing clearance. This foundation facilitated the creation of a leakage prediction model that incorporates bolt axial force parameters, thus enabling a quantitative assessment of flange sealing performance. This research provides a practical approach to evaluating the sealing performance of operational high-pressure flanges.