Design per ASME VIII or ASME B31.3?

[beh188]

I have a small flow device that will be classified under CRN registration rules as a "fitting". The primary application of this device is flow measurement and fluid transport. What design code should be followed - ASME VIII, or ASME B31.3? I am assuming B31.3 because the primary purpose is fluid transport, but would it be acceptable to also use ASME VIII? Are there any guidlines here?

The "fitting" is a special class of application, and does not need to have an authorized inspector, even for ASME VIII design.

Thanks.

 

[Kiwi2671]

beh188,
This excerpt from ASME VIII Div 1 listing items not in the scope of this code.

(e) piping components, such as pipe, flanges,
bolting, gaskets, valves, expansion joints, fittings, and
the pressure containing parts of other components, such
as strainers and devices which serve such purposes as
mixing, separating, snubbing, distributing, and metering
or controlling flow, provided that pressure containing
parts of such components are generally recognized as
piping components or accessories;

Regards,
Kiwi

 

[trottiey]

As Kiwi points out ASME VIII may not be the best choice. But the preamble to Kiwi's quote is "Based on the Committee’s consideration, the following classes of vessels are not included in the scope of this Division; however, any pressure vessel which meets all the applicable requirements of this Division may be stamped with the Code U Symbol" So the ASME code permits it if you want it.

In Canada, it is CSA B51 that governs the choice of codes, and section 8.1 will normally point you to the ASME B31.X piping codes. You'll find that many odd Canadian fittings then default to ASME B31.1 section 104.7.2, ("Specially Designed Components,") which can then send you right back to ASME VIII - but Div. 2 only! So in the end, you have many options which will have to be winnowed down in negotiation with your provincial jurisdictional authority.

Beware that there are important caveats in the Canadian codes if your fittings are meant for a special application, such as natural gas, medical, or nuclear.