Research on Relationship between Fractal Parameters and Compressive Stress of Metallic Gaskets

Metallic gasket seals are widely used in pressure vessels and piping. The failure of sealing systems is mostly caused not by the strength of flanges or bolts but by the leakage of the connections. The topography of sealing surface has a major influence on the leakage of the bolted flange connections. Based on the fractal geometry theory, the fractal characterization of the sealing surface topography of metallic gaskets was studied. The profile curves of metallic gasket surface under different compressive stresses were measured by the AF-LI type stylus profilometer. The fractal dimension, scale coefficient and characteristic length scale of surface profiles were calculated by structure function method. The influence of the compressive stress on the fractal parameters was also analyzed. Itpsilas found that the sealing surfaces of metallic gaskets were fractal, and the fractal dimension and the scale coefficient can be used to characterize the sealing surface topography of metallic gaskets under various compressive stresses. The formulae expressing the relationship between the fractal parameters and the compressive stress were obtained by the regression analysis of the test results. The results are helpful for the study on the sealing performance of metallic gaskets.