Leg Calculations 1

[PVGuy]

Can someone suggest a method to analyze the localized stresses on a shell wall from its leg supports (just the local stresses, the leg design is ok)? I considered WRC-107 but I do not think that it applies if the welds do not form a closed shape. FEA is NOT a possibility.

 

[solinar]

An acceptable non-FEA solution for shell stresses due to legs can be found in "Pressure Vessel Design Handbook" by Bednar (not to be confused with the "Pressure Vessel Handbook" by Megysey).

The book goes for about 100$ if I recall correctly.

The information you are looking for can be found in section 5.1.

 

[PVGuy]

Solinar,

Thanks for the quick feedback. Fortunately I have that here already. Unfortunately I did not realize it.

 

[codeeng]

In addition to Bednar you should still check shell stresses per WRC since there is a small moment to consider. Compress (if you have it) does this by default.

 

[PVGuy]

Codeeng,

Is WRC ok to use even when the welds only make three sides of a rectangle? Can you assume that the it is a rectangular attachment with dimensions of the weld along the top of the leg by the weld along the length of the leg?

 

[JStephen]

I remember seeing years ago a program available (for free, if I remember right) that designed leg attachments for tanks. If I recall right, it was a self-contained program that used FEA for the tank. At that time, it was shareware available through ASME. I don't think ASME has the shareware stuff anymore, but if you could locate that program, or an updated version, it might be a handy way to do it.

 

[chicopee]

one method for stress calculations is to determinee average shear stress thru throad and along entire length of welds; and compressive/tensile stresses due to bending momemts from external loads on legs. Then combine these stresses vectorially to determine resultant stress