Cubic Vessel Design

[obriend1]

Hi,

I have a small pressure vessel (3" x 3" x 3") that contains a centered 2" dia ID and square bolted end caps. I am assuming that the ASME minimum wall thickness formula in AD-201 still applies, but I am not sure because Section VIII Div 2 does not seem to mention anything about square or cubic vessels. Can someone please clarify the code when applied to non-circular vessels? Do I ignore the extra material that is on the corners and just take the thickness from the ID to the shortest distance on the outside of the vessel?

Thanks

 

[arto]

Look in Div 1 App 13 - Non-circular pressure vessels.
There's bending stress going on - can't just inscribe a circle & call it hoop stress

 

[obriend1]

Arto,

Thanks for your suggestion, but my vessel actually has a x-secton like a square nut (square outside with a hole centered in the middle) when looking into the vessel from the top. Unless I am missing something, the type of vessels in Div 1 Appendix 13 are non-circular ID's and x-sections. Does this still apply to my vessel? Does Div 2 deal with different vessel geometries not listed in D-2?

Thanks

 

[TGS4]

Your best bet would be to perform a Div 2 Appendix 4 design-by-analysis. You may also want to check out Div 3, I know that a number of their autoclave-type designs may not have circular external dimensions.

Good luck!

 

[prex]

If the inside of the vessel () is circular just take the minimum thickness all around and treat it as a circular shell.
Can't say anything about the square bolted end caps, as I don't know the geometry. If you can inscribe in it a flange that may be checked per App.2 then that's OK. Not sure to recall that correctly, but App.2 should have something also about non circular flanges.

prex

http://www.xcalcs.com

Online tools for structural design

 

[obriend1]

I would like to thank everybody for your advice and help.