In flanged connections, all gaskets have some level of fluid leakage, depending on gasket type and other factors. Using published Room Temperature Tightness (ROTT) test data and draft PVRC (Pressure Vessel Research Council) equations, a simple model to calculate the predicted tightness / leak rates of various gasket materials has been previously documented. The model assumes a set of draft empirical equations previously published by ASME / PVRC but with an incorporated stress loss factor. Tightness at flange assembly as well as following unloading can be estimated with the model. The EN 13555 test standard includes measuring the test gas leak rates for a series of gasket stresses but at a single operating pressure for each test. Correlation of EN 13555 data with PVRC model predicted leak rates over a range of manufactured gasket materials is demonstrated. The leak rate data for specific gasket materials have been found to compare favorably with the leak rates at assembly as determined in using the PVRC model. The application and corresponding limitations of certain EN 13555 gasket parameters are discussed. The end user may wish to consider the use of the PVRC empirical approach to estimate predicted long-term leak rates of competing gasket materials as a key factor in the gasket selection process.