Sure ARG,

The clue is in the interpretation that I referenced, VIII-1-89-287

There are 2 types of flanges quoted in this interpretation, the 1st one is the custom flane, meaning that you would perform an ASME Appendix 2 analysis to check the flange.

The 2nd one is a standard flange, such as B16.5 or B16.47, where you select the flange based on class, grade and get pressure rating from a table.

Per this interpretation, the answer is to consider the bolt stress ratio for a custom flange and not for a standard flange

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(1) bolted flange connections designed per Appendix 2?
(2) bolted flange connection which comply with an ANSI product standard or a Manufacturer's standard as permitted in UG-11?

Reply:
(1) Yes.
(2) No; the limiting hydrostatic test pressure shall be established in accordance with the applicable standard

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