ASME Sec. VIII Div.1, Appendix 13, Sketch (9) 3

[MHS1988]

Hi,
I have a problem understanding this clause from Appendix 13 of Sec VIII regarding the stress calculation for a rectangular vessel with more than 3 compartments. The part of the clause in question says:

13-9 (f) (2): "... For a vessel with more than two compartments, use geometry shown in Figure 13-2 (a), sketch (8) with three compartments having the maximum dimensions of the actual vessel (thus, a five- or six-compartment vessel for example would be analyzed as if it had only three compartments)."


I am confused about the interpretation as I think of two different approaches for an example problem.
Consider a 6-compartment vessel with an overall height of "H" and the biggest compartment height of "h":
- 1st Interpretation: Use sketch (8) with three compartments, each having a height of "h"
- 2nd Interpretation: Use sketch (8) with three compartments, each having a height of "H/3"

The wording seems to lean towards the 1st interpretation. However, my understanding of the code makes me wonder if it might lead to a non-conservative simplification. To add to my uncertainty, applying a similar approach to a sketch (8) vs sketch (7) vessel, which means using a 2-compartment sketch (7) vessel instead of a 3-compartment one with the maximum compartment height of the latter, results in stresses lower than that of a sketch (8). Therefore, I'm wondering maybe using a 3-compartment vessel instead of a 6-compartment one, with overall height of the former significantly less than the latter, results in calculated stresses being lower than what they actually are.

By the way English isn't my first language, which might be contributing to this clause appearing somewhat ambiguous to me. Any insights or clarifications would be greatly appreciated.

P.S.
I attached the sketches in question to this thread.

 

[DriveMeNuts]

In 13-9(f)(2), everything after "For example," is unintelligible English. Even the first half is confusing. I think with a small tweak to the wording, sense can be made:

13-9(f)(2) By selecting the compartment having the maximum 'h' dimension and then analysing the structure per (b) above for the case of a two‐compartment vessel and per (c) above for the case of a vessel with more than two compartments.

 

[SnTMan]

I would agree both with DriveMeNuts' interpretation and with the characterization of the language

EDIT: Having said that, I'd add that being able to parse out such language is a big part of what we get paid for

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MHS1988]

In 13-9(f)(2), everything after "For example," is unintelligible English. Even the first half is confusing. I think with a small tweak to the wording, sense can be made:

Quote:
13-9(f)(2) By selecting the compartment having the maximum 'h' dimension and then analysing the structure per (b) above for the case of a two‐compartment vessel and per (c) above for the case of a vessel with more than two compartments.

I would agree both with DriveMeNuts' interpretation and with the characterization of the language

Thank you very much, both you guys!
So as I understand the first interpretation in my original post is to be followed.

Again, your insight and input is very much appreciated.

 

[IdanPV]

The phrasing in VIII-2, 4.12.9 appears to be more optimal in my opinion.