"The Milestone Gasket Test Program is part of the Long Range Flanged Joint Improvement Program of the Pressure Vessel Research Committee. In these tests complex load/ pressure sequences are used to determine leakage performance and deformation response at room temperature of four types of gaskets: (a) A Spiral- Wound asbestos-filled gasket with an outer compression ring; (b) A Compressed-Asbestos gasket with a rubber binding; (c) A flat stainless-steel Doubled- Jacketed asbestos-filled gasket; and (d) A soft-iron Oval-Ring joint gasket. This paper presents an overview of the test program@ provides details on the test set-up@ test procedure@ leak rate determination@ etc. It also presents some typical results of tests carried out under stress-controlled conditions using Nitrogen at pressures up to 2000 psi (13.8 MPa). The analysis of the results is carried out in terms of the ""Tightness Factor@'' Lp@ which lumps pressure and leak rate into a single parameter. Regression analysis results are presented for tests involving flange facing surface finishes ranging from 32 to 1000 micro-in. AARH (0.81-25.4 micro-m). As the test program nears completion and further analyses are performed@ more results will be published. It is anticipated that the main parameters affecting gasket performance will be identified which will serve as a basis for defining a simplified production test procedure. More meaningful gasket design factors should thus be forthcoming."