Analyzing a storage tank corner weld

[IFRs]

Has anyone recomendations for using FEA to look at the fatigue life of the weld joint between the bottom and shell of a large high temperature storage tank?

 

[prex]

The stress there is well known and easily calculated by formula. I don't see what you would get with FEA that's useful to your analysis.

prex

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[corus]

prex may be right, but if the tank is high temperature then you may need to consider the stresses due to differential thermal expansion, and hence the temperature distribution in the tank and its supports first.

corus

 

[IFRs]

The tank is at 650 DegF. Does that help forumlate some FEA suggestions?

 

[corus]

I guess the bulk of the tank will be at 650 F, but that other parts may not be. Supports, for instance will be cooler, and hence you're likely to get localised cooling, and hence differentail thermal expansion. The variation in stress due to this will add to the variation in mechanical loads you'll get, and contribute to fatigue damage.

corus

 

[IFRs]

Corus -
Do you have a suggestion for any particular FEA software?

 

[TGS4]

I would NOT recommend that you - yourself - use FEA to solve this problem. It is far more complex than you can imagine. Hire a consultant with ample experience in this field.

Note that you may want to ask them to consider the use of the Structural Stress Method for Fatigue of Weldments regardin the fatigue of welds.

 

[corus]

In general fatigue assessment is based upon elastic stresses so you'd need a package that allowed thermal analysis with linear stress analysis, together with temperature dependent properties. Of course, calculating the stresses is one thing, interpreting the stresses for fatigue assessment is another.


corus

 

[IFRs]

TGS4 - any suggestions for a consultant?