AFC header design by UG-34 1

[fonti1977]

I am checking an AFC header calculation that uses UG-34 instead of Appendix 13 to get the thickness. I am thinking of requiring an ASME U stamp. This is because I saw a footnote in UG-34 (a).

Footnote 20 says "Special consideration shall be given to the design of shells, nozzle necks or flanges to which non circular heads or covers are attached [U-2(c)]." The AFC header is non circular.

U-2(c) says to mark vessel as per UG-116. And UG-116 seems to require U stamp.

Is my understanding correct? Is a U stamp required for a non circular header designed using UG-34?

 

[gr2vessels]

Sorry Fonty,
I have to confess that I don't know what an AFC header is, but a pressure vessel designed in accordance with ASME VIII require U stamp if operated within US (and Canada?). Outside US is meaningless. Including the non-circular headers designed using UG-34.
Cheers,
gr2vessels

 

[fonti1977]

Hi Gr2vessels, AFC stands for Air Fin Cooler. I'm still unclear what that special consideration in footnote 20 stands for. But thanks for the reply. If you can go thru the passage and give me your interpretation on it I'd really appreciate it.

 

[muld0020]

Not knowing all the details, I would say you should make sure that your vessel falls within the scope of ASME in Section U-1 since you are questioning the application of the "U" stamp. If there is a "U" stamp then applicable code calculations are required, however, if the vessel is not stamped it can still be built using the ASME calculations if applicable.

As far as footnote 20 goes, it just means you need to provide a safe design (which is essentially U-2(g)). You should provide some kind check on the bolting/gasket seating stresses / deflections. I would think this would come into play if you have higher pressures, temperatures, or long unsupported spans. If the vessel is hydro-tested (UG-99) this should proove footnote 20 has been accounted for.