Neelam, I think that if you had SIF values for the elements that intersect, you could build the model in CAESAR II with the trunnion, and apply the SIFs in the appropriate locations. The main problem with this is that the codes don't give us the SIFs for this type of intersection.
I would recommend looking into FE/Pipe. It is a relatively inexpensive FEA program that has tools specifically dedicated to trunnions and a variety of other piping/vessel components. It will give you the stress results, as well as code allowables and SIFs.
For more information, here is a web link: http://www.codecad.com/PRG.htm
The following images were captured from the program: