B16.5 Flange Pressure - Temp Ratings

[brucegr]

Does ASME B16.5 allow for exceeding recommened pressure - temperature ratings, for a short, one-off period of time. ie. during pipeline hydrotesting.

I dont have a copy of the code handy, but if it does in fact address the above issue and someone could email the relavant pages, it would really get me out of a bind.

 

[TD2K]

Are you talking about the nominal MAWP for flanges?

For example, class 150 flanges are good up to 285 psig (290 psig if I remember correctly for some materials). We hydrotest these at 450 psig (assuming of course, the piping wt is good for this pressure which 99.999 times it is).

 

[owlscreech]

B16.5a-1998 Paragraph 8.3, Hydrostatic Shell Test, states:

"The hydrostatic shell test for flanged fittings shall be no less than 1.5 times the 100F rating rounded off to the next higher 25 psi increment."

This says that the manufacturer has tested them at 1.5 times 100F rating. You were talking about "pipeline hydrotesting." In that case the rules to apply are from pipeline code used for construction, e.g. B31.1, or the jurisdictional rules (e.g., State Rules). There may also be repair rules. For B31.1 the 1.5 is applied to piping design pressure but it cannot be more than the maximum allowable TEST pressure of any non-isolated component. The TEST pressure is the 1.5 times 100F rating rounded off.