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B16.5 Pressure Rating Question

B16.5 Pressure Rating Question

B16.5 Pressure Rating Question

(OP)
For the normal -20-100 DegF Temp Range, a few questions:  

MAWP is 285 psig..I know that.
Max HydroTest Pressure is 450 psig.  Is this correct?

I don't remember Max hydro being that much above MAWP.  

Also, do these ratings hold for plate flanges (ie flanges of specified the thickness, per 16.5 dimensions cut from plate, and double fillet welded...so they have no hub)?

Finally...FF vs RF.  I recall the ASME Section 8 (back when I actually had access to it...and was forced to actually use it) treated FF flanges in separate class, analytically, because the gasket extended out to and beyond the bolts...which makes calcs much harder.  Are FF flanged derated vs the RF flanges, which the 285 psig is based on.

Thanks in advance.   

RE: B16.5 Pressure Rating Question

If you could provide a few more details such as whether this is work associated with a pressure vessel or a piping system and what Design Code is in use it would be helpful.
 

RE: B16.5 Pressure Rating Question

I think you can ordinarily hydrotest a flange to 1.5 times its rating rounded to the next highest multiple of 25 psi; don't remember off hand where I saw that, though.
 

Regards,

SNORGY.

RE: B16.5 Pressure Rating Question

(OP)
Vertical pump discharge head design.  ASME does not apply.  Water piping system...up to 24".  Looking at some sub-component design issues..and prefer to make the ratings of these components match up to the flange ratings for consistency.  So I would envision a normal pressure series...that matches the 150# class...and a higher pressure series of components that matches 300# class.  Design MAWP and Hydro would match the -20-100 Def F ratings for std flanges....   

RE: B16.5 Pressure Rating Question

ASME B16.5 (in Clause 8.2.2) specifies that flanged fittings be pressure tested at a minimum of 1.5 times the pressure rating, rounded off to the next higher 25 psi increment.

Cheers,
John

RE: B16.5 Pressure Rating Question

(OP)
Thanks guys.  I was just making sure...

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