Exceeding ANSI/ASME B16.5 Flanges pres/temp ratings

[Diborane]

Hello,

ASME B31.3 gives specific exceptions which allow the pressure in process piping to exceed the recommended rating. Such as 20% for no more than 50 hr at one time or 500 hr/yr.

Does such an exception exist for ANSI/ASME B16.5 code? I did not see such an exception in code book I have (albeit outdated 1981). Can the ASME B31.3 exceptions be safely used for B16.5?

 

[TD2K]

B31.3 includes the B16.5 standard so yes, the 20% ad 33% exemptions allowed per B31.3 includes piping with flanges, it would be a pretty useless exemption if it didn't.

Look at Design Criteria, General, section 302.1 (mine is an old copy so the numbers may not match exactly) and 302.1.1 "Listed components having established ratings". Section 202.1.1 goes on to reference table 326.1 which refers to B16.5 for flanges.

Back to 202.1.1, this section states:

"The provisions of this Code may be used at the owner's responsibility to extend the pressure/temperature ratings of a componet beyond the ratings of the listed standard".

Be sure all the provisions of B31.3 allowing excursions are met, it's just not an automatic 'this is okay'.