Multi-scale contact characteristics and leakage prediction of flange seal based on fractal geometry

Abstract

Flanges serve as the sealing and connecting components in nuclear power plant pipelines and pressure vessels. The contact gaps between flanges and gaskets can lead to flange sealing failure. Therefore, optimal flange sealing surfaces are essential for ensuring the safety and reliability of airtight pipeline systems. This paper examined the flange sealing surfaces in a nuclear power plant. A sealing contact model was established according to the characteristic parameters of the surface contours measured during the experiment, while the finite element method was used to determine the sealing contact characteristics and predict the leakage of the rough sealing contact surface. The results indicated that the surface roughness had a multi-scale effect while the sealing state was related to the sealing characteristics scale. The sealing surface morphology, material properties, and operational conditions directly affected the sealing interface structure and sealing performance. In addition, the contact clearance of the sealing surface decreased in conjunction with increased applied load, normal compression displacement, and surface roughness, while the surface leakage rate increased at a higher surface contact clearance and pipeline conveying pressure.