SIF on miter bend where D/t.>100

Dear members,
Using Table D300 from B31.3 for calculating SIF and Flexibilty F, equations are no longer valid since D/t is over 100.
I would appreciate any guidelines for performing these calculations, in order to have a realistic approach.
NB: Hoop stresses are the primarly stressesand are not not within the allowble.

Thanks in Advance.
Yani.

Yani,

This one has already done the rounds. Have a read through Caesar - II & ANSYS with PIPE16