On the Leak Through a Spiral-Groove Metallic Static Ring Gasket

The diffusive and viscous leaks through a model spiral groove static ring gasket are studied analytically. This system is characterized by a transition from a leak through radial passages to a leak following the spiral groove as the load increases. The study concentrates on the transition. The results indicate a sharp (“critical”) transition with variations of several order of magnitudes in the leak flow rates for small changes in the contact area, i.e. the applied load. It is also shown how results for a diffusive leak and a viscous leak can be combined for identifying the transition. The influence of surface errors of form (waviness) is also considered. Although generally detrimental to tightness, it is however shown that errors of form could be beneficial to tightness for the high loads if their amplitudes are slightly smaller than the groove average depth.