Minimum Design Pressure of Vessel

I don't recall that ASME specifies such a minimum. It has been some time since I was a vessel designer, and I'm not sure about this. However, since no one else has replied as yet, I'll venture this tentative opinion.

Read through the first part of Section VIII. Vessels with less than 15 psi are not considered pressure vessels per Section VIII. So I guess technically that's your answer.

Theo,

Clearly, this is a "rule of thumb" and an expert opinion.

The 50 psi minimum design pressure is suggested in order to ensure a reasonable minimum strength design for vessels that are frankly subject to other types of loadings.

ASME VIII is a mature, tested and verified set of rules that can be used to design safe vessels......but it starts at 15 psig !!

The ASME and other codes use the design pressure to size wall thicknesses for PV shells and heads. For large vessels that are subject to low pressures ( slightly greater than 15psig) this does note ensure a robust construction that will sustain other reasonable loads.

Suggesting 50 psig minimum is a way to make up for the fact that the USA does not have an acceptable code of construction for containers that are operated from 2.5 up to 15 psig

My opinion only.....