Hello again IdanPV. I thank you very much for your opinions.
In your last post, you exclusively use references from ASME I, to reach the conclusion that this Section should be used to manufacture the completed boiler. We already agreed on this in previous posts.
However, if from the beginning we approach the question exclusively from VIII-1, it is found that U-1(g)(1) is an alternative way to build the completed boiler, since U-1 does not refer to the "pressure vessel boiler ", but to the "boiler" itself.
On the other hand, the two options are also included in ASME I, Preamble, fourth paragraph from the end, which says: "Unfired steam boilers shall be constructed under the provisions of Section I or Section VIII."