How would I go about building a CII-model of a cone/reducer that on one side is 28" and on the other 16"? WT = 6 mm.
Perpendicular to the centerline of this reducer is a nozzle of 28" diam.
Is modelling a pipe of average diameter (22") with a rigid element (represented by RRR)between centerline and the intersection of cone and the 28" nozzle a correct approach?

Thank you in advance.

Hello,

I think the described geometry is too complex to evaluate with a beam theory model. You seem to be describing a fabricated "Tee" fitting with a reducing leg exiting from the "run". Calculated beam bending stresses in such a construct would be meaningless.

In general, you must be very careful when you get systems with relatively large D/t ratios. At the supports you will have local membrane stresses (the pipe will ovalize and/or there may be very local depressions at the point of contact with the support) and none of these stresses will be calculated by a beam model. Just a few of the things you should think about.

Regarding large reducers: perhaps the best approach is to model it in several (maybe like four) "steps", reducing the OD and WT in each step as appropriate. It would be interesting to know what SIF one would use with such a component.

If the component you describe is included in a fairly sizable piping model, perhaps you could model it as a (several step) reducer with the 28 inch outlet nozzle modeled as a "rigid link". Make all the piping (OD's and WT's)in and out of the component be as designed. Then have CAESAR II calculate the overall system forces and moments. Then look at the calculated forces and moments at each of the three "ends" (larger OD end, smaller OD end and end of the 28 inch nozzle). Take those forces and moments into an FE/Pipe (or equal finite element) model to calculate all the stresses and use Section VIII, Div,. 2 rules to evaluate the results. This would probably give you the best approximation.

Just a thought.

regards, John.