HISTORY - (FOREWORD ASME B16.47-2006)
In November 1980, a task forcewas appointed within Subcommittee C of the American National Standards (ANSI) B16 Committee to develop a standard for pipe flanges in size NPS 26 through NPS 48. Every attempt was made to standardize those dimensions that existed within the industry for the materials covered by ANSI B16.5.
Prompted by suggestions received from committee members, the task force was authorized to increase the size range to NPS 60. The first draft was developed in December 1982 to include Class 75 through Class 1500 for the size range NPS 26 through NPS 60.
Flange dimensions were based on the Manufacturers Standardization Society Standard Practice (MSS SP) 44 flanges, except for Class 75 flanges that are ANSI/API 605 flanges.
At the request of the American Petroleum Institute (API), flange dimensions, in accordance with the API Standard 605, were included in the subsequent drafts.
Class 1500 flanges were deleted due to a lack of interest in using large size flanges in that pressure-temperature rating. The API-605 flanges for Class 150 and 300 and for sizes NPS 36 and smaller for classes higher than Class 300 are not compatible with the MSS SP-44 flanges.
Thus, the MSS SP-44 flanges are designated as Series A flanges and the API-605 flanges are designated as Series B flanges in this Standard. Materials covered in this Standard are as in ANSI B16.5, except nickel base alloys are excluded. Pressure-temperature ratings are in accordance with ANSI B16.5.
In 1982, American National Standards Committee B16 was reorganized as the American Society of Mechanical Engineers (ASME) B16 Committee operating under procedures accredited by ANSI. Following approval by the Standards Committee and ASME, approval as an American National Standard was given by ANSI on June 12, 1990.
The 1996 Edition allowed flanges marked with more than one material grade or specification, revised flange face finish requirements, revised pressure-temperature ratings for several material groups, added permissible flange facing imperfections, added blind flanges for Series B flanges, and included several other revisions. Following approval by the Standards Committee and ASME, Boiler and Pressure Vessel Committee, ANSI approved the previous edition as an American National Standard on October 3, 1996 with the new designation ASME B16.47-1996.
This 2006 Edition is presented in metric units, as primary units, with U.S. Customary units in either parenthetical or separate forms. Mandatory Appendix I has been provided after the main text for convenience to cover ratings and dimensions in U.S. Customary units.
Inch dimension bolt holes were retained for flanges manufactured to metric dimensions to avoid fit up problems. Development of metric dimensions was done to reflect the intended precision of the dimension rather than by numerical conversion.
For some materials pressure-temperature ratings have been revised to reflect revisions to material strength properties (tensile and yield) listed in the ASME Boiler and Pressure Vessel Code, Section II. Some materials have been assigned to different rating tables in order to minimize changes to ratings for commonly used materials. ASME B16.47-2006 was approved by the American National Standards Institute on November 6, 2006.