BigTank,
Suggest you design the flange as 'ring type integral', not 'ring type loose'. If you try 'ring type loose' you will have a problem defining the flange ID in COMPRESS since it will be smaller than the shell OD. For 'ring type integral' the design calculations are the same as Fig. 2-4 Sketch (8)thru (10a) but you will need to be sure the attachment weld meets the referenced requirements of Sketch(11). You may need to adjust the weld size in COMPRESS.
Don Kurle PE
Codeware Technical Support