Dear Carletes,

I've used the both calculation approaches.

In my understanding, the both methods were developed for "straight pipe - pipe trunnion" type junction.

However, in my opinion, ASME Case 392 method yields more conservative results than Kellog approach. Besides, ASME Case 392 regards the local stress states developed both in the pipe and in the trunnion wall, while Kellog method is applied (after my knowledge) only for the main pipe stress checking.

So, unless otherwise required by the Project specifications/procedures, I generally use ASME Case N-392 method, both for straight pipe and pipe elbow trunnions/dummies. This aaproach appears to be conservative enough for the both cases.

However, if overloading/overstress problems occur and the "pipe/elbow-trunnion" reinforcement possibilities are limited, it would be necessary to involve Finite Element Analysis approach (such as FE Pipe software) for an accurate analysis purpose.

If you still prefer to use Kellogg approach, be careful to superpose the local stresses developed by the attachment local loads over the initial stresses induced by the main pipe internal forces and moments.

In the past I saw some versions of Kellog method (developed as mandatory Project procedure) where the initial stresses developed by the main pipe internal forces and moments were ignored.
From this point of view, it should be noted that ASME Case N-392 takes into account explicitly the initial stress states of the main pipe.

Best regards,