Hello friends.

I have a query regarding the SIF for lateral connections.

Background:-
BP's spec on flexibility analysis states:-
Stress intensity at 45 degree fabricated tee is the same as for 90 degrees Tees provided the header thickness at the opening complies with paragraph 304.3.3 of ASME B31.3 using an enhanced design pressure as per the standard equivalent pressure calculation.
Otherwise the branch shall be checked for pressure containment(area containment) to ASME B31.3 para 304.3.3 using the design pressure, as per the line list, and checked for flexibility stresses sing the following enhanced stress raisers:-
90= SIF from B31.3 X1
60= SIF from B31.3 X1.25
45= SIF from B31.3 X2.25

Query:-
If my understanding is correct then,

1. We can use the same SIF for branch connections(other than 90 degree) if we evaluate the branch connection at pressure higher than design pressure.
However, I don't know the method of calculating "enhanced design pressure as per standard equivalent pressure calculation". Any ideas about this calculation?

2. We can evaluate the branch connection at design pressure only but we have to increase the SIF's with factors specified. Any rationale to increase the code SIF's? Maybe these modified values are coming based on BP's experience and verified by fatigue testing of branch connections per ASME B31J.

Neeraj
"The harder I work, the luckier I become"