External Design pressure or FV

[darrenyee88]

I read this statement specifiying " if a vessel is designed for ess than 15 psi , and the external pressure condition is not going to be stamped on the nameplate, the vessel does not have to be designed for external pressure condiiton. Where can I find this in ASME Sec VIII 1 in order to support this statement?

 

[Nfroh]

You do not need to stamp a pressure vessel if the internal/external design pressure is less than 15 psi (U-1(c)(2)), but it does not mean that you should not perform a design calculation. As soon as there is over/under pressure it’s MF responsibility to assure that the vessel is safe.