Loose vs Option/Integral flange requirements per Appendix 2, 2-4 (3) ?

[bayardwv]

I have an old internal design memo stating that for vessels over 300 PSIG the flange has to be calculated as an INTERGRAL flange in accordance with App.2, 2-4(3).
I question the accuracy of this because ASME B16.5 Slip-On style flanges are rated greater than 300 PSIG yet are still attached using only fillet welds.

Does anywhere in Section VIII, Div.1 state when a loose type flange is not an allowable design?

 

[mk3223]

IMO, it should be acceptable if the bolting load and allowance stress of either loose or integral flanges meet the BPVC code requirements based on the vessel design pressure and temperature.
The internal design memo could be your company preference for the vessel design based on the operation experience.

 

[KVdA]

The memo did not state it is not allowed. The memo stated that the calculation must be performer d as You would do an integral. ASME is imo not that clear but iT is allowed to Calc loose type as integral. Difficult part is to define the hub thichknesses etc