Leak prediction through porous compressed packing rings: A comparison study

The Prediction of leak rate is a significant challenge in the design of bolted flange joints and valves. With the increase of the strict regulations on fugitive emissions appropriate leakage-based standard design procedures are required. Fluid flow through porous media is a very attractive theory that can be used to predict leak rates through gaskets and compression packings. Valves that are the major source of fugitive emissions in the category of pressurized equipment use compression packings and seals the design of which is not covered by a standard design procedure. In this study, three different models; capillary, concentric cylinders, and modified Darcy's models, are used to characterize the sealing behavior of graphite-based compression packing rings. Based on data from several experimental tests, the ability of each model to predict accurate leak rates is evaluated. The comparison between the predicted and the measured leak rates is conducted for different molecular size gasses and a wide range of gland stresses and gas pressures.