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Knowledgebase Article 1056
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Question:
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How does COMPRESS determine the UG-99 stress
ratio for flanges designed to Appendix 2? I
get a value different from what is reported
in the Hydrotest Report.
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Answer:
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According to UG-99(a)(2)(b), the MAWP is
multiplied by "the lowest ratio (for the
materials of which the vessel is constructed) of
the stress value S for the test temperature on
the vessel to the stress value S for the design
temperature (see UG-21)". For flanges, the
values for S also include the bolt material. This
is often overlooked.
(See http://www.codeware.com/support/faq/1033.html for discussion
of testing for standard ASME B16.5/B16.47 flanges)
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