HISTORY - (FOREWORD ASME B16.20-2007)
Ring-joint gaskets and grooves probably originated in the boiler field, where they were used in various forms for manhole covers, autoclaves, and other closures; however, it was in the oil industry (both in the production and refining of oil) that they received the greatest recognition and were developed into their present form. Their use expanded steadily as temperatures and pressures were increased in steam plants. Tests examining their application in flanges and valves were conducted as early as 1928.
In June 1936, the American Petroleum Institute (API) issued Tentative Standard 5-G-3 on Ring-Joints for Steel Flanges and Flange Unions for use with API Tubular Goods. This standard was known as API Specification 6B, Ring-Joint Flanges. Following the acceptance of ring-joints for flanges and valves by API and the issuance of their standard, ASA B16e on Steel Pipe Flanges and Flanged Fittings was revised to include them, and the 1939 edition included standard dimensions for a full line of ring-joint flanges based on the API standard. Development work continued and API formulated Standard 6E, Specification for Wellhead Equipment, which included ring-joints not covered in ASA B16e-1939.
In 1949, the American Standards Association (ASA), Sectional Committee B16, Subcommittee 3, Steel Flanges and Flanged Fittings, assembled the available information on ring-joint gaskets into a single standard. ASA approval was granted on April 30, 1952, with the designation ASA B16.20-1952.
An updated version was submitted and ASA approval was granted on April 4, 1955, with the designation ASA B16.20-1955. Ring gaskets for Class 900 (900 lb at that time) in sizes NPS 26 through 36 were added and ASA approval was granted on April 2, 1956. The standard was reviewed in 1962 and approval was granted by the ASA on April 25, 1963.
The standard was again reviewed and approval was granted by the American National Standards Institute (ANSI) on April 25, 1973, with the designation of an American National Standard. API requested that ASME convert their gasket standard, API 601, into an ASME American National Standard. As a result of that request, the standard was expanded to include requirements for spiral-wound and jacketed gaskets that were formerly listed in API 601, 7th edition, 1988. Also, ring-joint groove dimensions were not included, because they were included in ASME/ANSI B16.5-1988, titled Pipe Flanges and Flanged Fittings, and ASME B16.47-1990, titled Large Diameter Steel Flanges.
The 1993 edition was approved by the B16 Standards Committee and, following approval by ASME, approval by ANSI was given on January 22, 1993, with the designation ASME B16.20-1993. In the 1998 edition of ASME B16.20, reference standards were updated, a quality system program annex was added, inner ring inside diameters for spiral-wound gaskets were revised, and several editorial revisions were made. Following approval by ASME B16 Subcommittee G and the B16 Main Committee, ANSI approved this American National Standard on November 20, 1998.
In 2007, the standard adopted metric dimensions as an independent standard to the U.S. Customary units; Mandatory Appendix I has been added to cover dimensional tables in U.S. Customary units. Following approval by B16 Subcommittee G, the Standards Committee, and ASME, ANSI approved this American National Standard on October 19, 2007.