Hello all,

I am doing the stress calculation of a horizontal header with 36" Sch.10 that it has a short vent branch 8" Sch.10s in the top of the pipe section of the header with reinforcing pad.

In the first approach we have modeled that branch directly from the center of the header and we have inputed the SIF as reinforcing pad in the intersection between header and branch. The result obtained for expansion case was 90% of allowable.

How can be that possible? This branch with a free end in expansion case should have almost free expansion with no stresses and the stress value obtained in the intersection should be just the stress value of the header pipe (13% approx.)

We will change the model in order to avoid this result. We will model a rigid from the centerline of the header pipe to the wall and we will add a FEA SIF in the node of the branch element. But.., I would like to understand the 90% stresses in expansion case obtained from the first approach.

Than you very much in advance

Regards