Api tank with an intermediate cone API 650/API 620/ EN14015.

[Luike]

Dear Colleagues:

At this moment , i'm designing a tank using European standard to perform all calcs. But when I try to obtain results for conical course with apex angle equal to 30 or less.

The exactly problem is to find an method using referred codes to determine requires thickness in above cone. Using certain softwares, I can reach to introduce their geometry and materials but unfortunatelly , I can't get a logical way by means of equations.

Could anybody to recommend me any code (diferente to ASME) or simmilar to get reasonably results, ways of reinforcement (use of some courses to fabricate cone with different thickness from bottom to top. Any advise will be apreciated.

The shape of this tank aprox is 5 meter diam, cone 5.2 m length (from 5 m to 10 mm ) 10 meter diameter part and conical roof.
Total elevation of top part of upper course is 42 mm from base (0 meters)

Best regards and thanks in advance.

 

[JStephen]

First off, I'm not sure I understand exactly what your shape actually is.

The methods in API-620 can be applied to a variety of shapes with an axis of symmetry. If it's a standard tank shape, it's fairly straight-forward. If it's not a standard tank shape, it may take additional terms and careful considerations of the signs and of the weights in the free-body to get the appropriate answers. This analysis won't give you bending stresses at the junctions, so it may or may not satisfy some other code (for example, can't be use for ASME vessels).

I believe Roark's Formulas for Stress and Strain and Timoshenko's Theory of Plates and Shells go into the bending and deflections of cones under different loading, and could be used for a solution if bending stresses were also required. It's likely to get complicated.

API-620 and similar codes will give you allowable stress for axial load in a cylinder, which can be applied to a cone shape. API-620 does not address circumferential compressive stresses, though.