This has probably been raised on may occassions but I would appreciate some guidance on establishing SIF's for reinforced tees where the angle between the branch and header is less than 90 deg. If the most appropriate answer is that we have to do an FEA to establish the SIF's, are they established by ratio of maximum peak stress in the header and branch compared to the peak stress in a butt welded joint in each? Whilst this approach is defendable it remains a subjective assessment since the magnitude of peak stresses depend on issues such as final weld profile and the geometry tolerances to which any reinforcing pad is made.

There seems to be no guidance available in ASME III Div 1 NB-3680 and ASME VIII Div 2 App 4 Article 4-6 does not cover laterals with external reinforcement (pads).

Any feedback/recommendations would be appreciated. Merry Christmas to all readers!