Do insert flanges conform to the requirements of ASME B31.3?

The answer to this question is YES. Process Piping, ASME B31.3, provides guidelines for the design of flanges which are not included as standards in Table 326.1 of this specification. These requirements are found in paragraph 304.5.1 of the code. This specifically says, “flanges may be designed in accordance with the Boiler Pressure Vessel Code, Section VIII, Div 1, Appendix 2 or Appendix Y, depending on whether the gasket OD is inside or outside the bolt circle. Flanges may be qualified by the requirements of paragraph 304.7.2. This paragraph applies when Appendix 2 or Appendix Y are not applicable and states that the design is to be based on calculations consistent with the design criteria on B31.3 and substantiated by one or more of the following:

  • a) Extensive & successful service experience under comparable conditions with similarly proportioned components.
  • b) Experimental stress analysis similar to that described in BPV Code, Section VIII, Div 2, Appendix 6.
  • c) Proof testing in accordance with ASME B16.9, MSS SP-97, or BPV Code Section VIII, Div 1, UG-101.
  • d)Detailed stress analysis such as finite element.” (passage taken from the ASME Code)

Insert flanges are based on ASME/ANSI B16.5 flanges, and contain the same ring-type elements. Insert flanges can be reliably designed to Appendix 2 of the BPV Code, Section VIII, Div 1. Insert flanges have passed the test of successful years of service since they have been used for over 75 years.