Irregular shapes under Section VIII, Div 1?
Irregular shapes under Section VIII, Div 1?
(OP)
I'm trying to create a calculation package for a pressure vessel that does not have a standard shape (i.e. not a shell, hemisphere, conical, etc.) Is there a way to perform this calculation under Division 1 rules? For instance, if I can fit a hemisphere entirely inside my part, can I design it as a hemihead knowing that my calculation is conservative? I would appreciate your reasoning either for or against using this approach.
My second question is regarding the 3000 PSI limit in U1(d). Is there any clarification about what the "additional design principles and construction practices" are for vessels rated above 3000 PSI?
Thanks,
My second question is regarding the 3000 PSI limit in U1(d). Is there any clarification about what the "additional design principles and construction practices" are for vessels rated above 3000 PSI?
Thanks,





RE: Irregular shapes under Section VIII, Div 1?
hhamza- Coupling your statement above of what you believe to possibly be factual with your prior query thread794-389325: ASME SECTION VIII, DIV 1, FIGURE UG-37.1 FORMULAS about how to calculate area of reinforcement for openings, I have a couple suggestions.
First, read the Foreword. Specifically, the fourth paragraph. I'll copy it in to here for easy reference:
Second, regarding your query about the 3000 psi note, I'll suggest you read ASME PCC-2 Article 5, Appendix II and III. Then re-read the fourth paragraph of the Foreword.
RE: Irregular shapes under Section VIII, Div 1?
RE: Irregular shapes under Section VIII, Div 1?
Within the rules contained in Division 1? No. Whatever your shape is, I can guarantee that the stresses will be more than that of an equivalent hemispherical head. Therefore, your contention that such a calculation would be more conservative is incorrect. My rationale is based on strength of materials and thin-shell theory.
At pressures above 3000psi, the thin-shell theory assumptions built-in to the Division 1 calculations are generally rendered invalid. Rather than trying to figure what these additional design principles and construction practices are, you be better off using Division 2. However, if your pressures exceed 10,000psi, then, as recommended by Division 2, paragraph 1.2.2.2, you would be better served by using Division 3.
RE: Irregular shapes under Section VIII, Div 1?
Also note that in some cases, it is advantageous to change the shape to match the design methods available, even if other shapes might actually be workable.