Design of Vacuum Vessel 1

[Outlaw500]

I need some help in determing allowable stresses on a large vessel.

I have a large diameter vessel: 15'-0"
Wall Thickness: .1875 inches
Height: 12 feet

Atmoshpheric pressure outside and a vacuum inside of about 25 in water.

I know I'm way overkill on hoop stresses what I'm concerned about is how do I check slight deformations and buckling of the cylinder?

Or any other ideas of how to go about this?

 

[jte]

Outlaw-

If this is an ASME VIII Div. 1 vessel, just use the code... UG-28 will get you started. If this is a non-stamped tank, you can still use the VIII method to check. Roughly 1 psi external pressure isn't much, but its not a bad idea to run the numbers...

jt

 

[MJCronin]

Agreed,

ASME-VIII is one method you can use to check for the slight vacuum conditions, but...

You may be very close to the allowable limits under ASME.

You also might consider use of the methods contained in the latest version of API-650 or alternately, discuss this case with a designer of atmospheric storage tanks.

To the best of my recollection, a numerical methodology for evaluating storage tanks under slight vacuum was to be included in the latest edition of API-650.

-MJC

 

[MJCronin]

Outlaw..

http://www.eng-tips.com/viewthread.cfm?qid=166872&page=1

-MJC