Effect of Surface Roughness on Compressive Stress of Static Seals : 1st Report, Basic Experiment

The authors have investigated the effect of surface roughness, appearing on turned surfaces, on compressive stress for allowable gas leakage from static seals. The following results were obtained from gas leak tests in which sealing surfaces of both annealed copper and stainless steel or alloy tool steel were mated together. (1) In order to ignore the surface roughness and the combination of materials, the compressive stress for sealing had to be nearly equal to the tensile strength of annealed copper. (2) In the case of the combination of annealed copper having its surface polished by an emery paper and stainless steel having a turned surface, the compressive stress for sealing did not depend on the surface roughness and was almost constant. (3) In the case of both surfaces being turned, the value of maximum height roughness in which the minimum compressive stress for sealing exist was found in the region between 10 μm and 50 μm