Even after manually overriding SIFs of a header-branch connection in all the connecting elements, bending stresses differ with respect to whether i define the type of branch.

For your information am using WRC 329 and Class 1 branch flexibility. and am manually overriding the Code SIFs since its a 45°branch.

Do i need to define the branch type even if i have defined the SIFs manually.

Yes you have to define an intersection type. If you don't make a selection CAESAR II can't determine "in-plane" versus "out-of-plane". The actual tee type you select really doesn't matter since you're overriding the SIF values.

Dear Sir
Do you mean to say that CAESAR II will be able to understand the direction of Bending moment (inplane or outplane) only by defining the branch type.
If possible could you please explain.

Thanks

The stresses on a pipe element are determined from the forces and moments on the ends of the element (think free body). If you're looking at a single pipe, what is in-plane and what is out-of-plane? You can't tell. However, for a single piece of pipe this isn't important because different SIFs are not applied.

We only need to know what is in-plane and what is out-of-plane when dealing with a Code that applies different SIFs. In order to figure this out, a tee fitting must be specified, otherwise CAESAR II never bothers to determine in-plane versus out-of-plane.