Dear all,

I want to model a fabricated tee with a reinforcing pad in Caesar II and have some doubts when calculating SIF for branch connection.I don´t know what are exactly these two parameters: the fitting outside radius and the crotch radius.

I have looked for it in ASME B31.1 Appendix D and it doesn´t appear. There are examples for weldolets or similar but not for reinforced fabricated tees with a pad. Any help?

Thank you in advance.

Compared to a non-reinforced fab. tee, to model a reinforced fabricated tee you only need to add pad thickness to the Caesar II input. This will allow correct calculation of the sif's.

Thank you.

I had already tried it but if I only introduce the pad thickness the SIF of the branch (not the header) doesn´t change when I introduce a reinforcing pad, I change its thickness, etc
That´s why I think it´s necessary to introduce this two parameters in order to obtain a more accurate result.

Perhaps the SIF of the branch is not affected by the fact of installing a reinforcing pad or not?

Regards

The sif's for branch and header should be the same, in accordance with ASME B31.3 App D, which I assume you are using.

Caesar only needs the branch type to be defined once. I have tried on a test model, specifying a reinforced tee + pad thickness only on the header, and only on the branch. In both cases the sif in results were correct for all three legs.

If you enter want to manually enter sif's, you must do so on all three legs of the branch.

Maybe you should try a few tests on a simple model ?

I am using B31.1 in Appendix D there is a specific equation for SIF of branch connection in which I don't know how affects the reinforcing pad.

Thank you.

The fitting outside radius is rp in Fig. D-1 of B31.1 Appendix D. If omitted in Caesar II this defaults to the branch outside radius, which is conservative except in Fig. D-1(d) which is the same. The branch SIF (for reduced intersections) is inversely proportional to the value of rp, so as this is increased the SIF will decrease. There is no crotch radius for reinforced fabricated tees. The Pad thickness is only used in the Run pipe flexibility characteristic calculation so does not affect the branch SIFs.

So the SIF of the branch acc/B31.1 can not be reduced by installing a bigger or thicker reinforcing pad?

How is possible then to reduce the SIF of the branch without increasing the schedule of the branching pipe?
Thanks.

If you want to force Caesar II to ignore the branch equation and instead use the same SIF equations for the branch as the header (not necessarily a bad assumption for an RFT as MoverZ points out) then you can do that. Go to the SIFs and Stresses tab in Configure/Setup and activate the directive entitled "No RFT/WLT in reduced fitting SIFs." Then your branch SIFs will be affected by your pad thickness the same as your header SIFs are.

Sorry,but ASME B31.1 allows that? I think that the SIF equation to be used for the branch is clearly stated in B31.1 but what is not so clear is if it is affected by installing a reinforcing pad.

Thanks again.

Installing a reinforcing pad does not affect the branch equation, which I think is clear. As to what the code allows, I will let you decide that for yourself. The option is there in Caesar II because some people do believe that the branch equation is not applicable to RFTs.