Pressure vessel design with dimpled jacket

[RIMACH]

Design engineers... I need your help!

I have been designing a non-circular pressure vessel based in ASME code but I have some problems(doubts) 'cause this pressure vessel has a inner shell (a plate) & a jacket (dimpled plate).

We used to designing this type of vessel with some reinforcements, instead of use a dimpled plate and my main question is to know how the change affects or how to validate the safety of the new vessel?

Data of importance:

Internal pressure: 32 lb/in2 @ constant volume.
Material: SA-240-316L (inner shell)
Material: SA-240-304 (jacket)

Someone could help me with the design? to be more specific with the calculations?
Thanks!

RIMACH
ingrimach@hotmail.com

[AndrewNew]

Hi,

If you have the ASME codes they should give you details of the stress analysis you need to do. I believe there are a couple of methodologies, design by rule and design by analysis, and you might need to go down the design by analysis route because yours is a previously untried design (I am guessing). You will have to perform various design checks, including checks against failure by gross plastic deformation, incremental collapse and fatigue. If you are using FEA, you can find several useful publications on the NAFEMS website (www.nafems.org), e.g. Warrior, N A, and Durrant, J C, The Application of Finite Element Modelling to Pressure Vessel Design Codes (search for "pressure vessel" using the search box on the home page).

Hope this helps!

Cheers

Andrew

[hmck57]

I agree with Andrew - the ASME codes should cover the design requirements. However it would be best to do some modeling of the design, whatever code requirements you decide to use (design by rule or design by analysis) so that you can be sure you understand how it carries load. If you are competent in FEA this would be the best alternative. Some hand analysis could be useful but it must account for the bending stresses.

Is the vessel cylindrical (constant cross-section)? A non-round cross-section will "try" to become round under pressure. For instance, an elliptical section will become less elliptical (more round) under pressure. Again take note: In any non-round cross-section there will be bending effects which must be accounted for.

Is the inner shell attached to the outer jacket? If so, how? I presume the dimples run in the circumferential direction - if so they should act as a flange or ring stiffener by providing section depth. Hoop direction stiffeners will develop bending stresses as well. If the dimple stiffeners run in the axial direction they will try to straighten out and have some very high stresses indeed.

Hope this helps - if you need more help provide more details and I'll be glad to help.

[rushinpatel]

you go with this link and checked it,


thank u...,

http://www.pveng.com//Sample/Vertical/Vertical.php.