Hello friends.

I have a query regarding the SIF for butt welded fittings

Background:-
Appendix D of ASME B31.3 states:-
The designer is cautioned that cast butt welded fittings may have considerably heavier walls than that of the pipe with which they are used. Large errors may be introduced unless the effect of these greater thicknesses is considered.

ASME B16.9:-
No positive value for the fitting thickness

Practical methods of Fitting manufacturing:-
Based on my experience from visiting a lot of fitting manufacturers, the manufacturer start with a thicker plate so that they can achieve required thickness(with specified under tolerance). They have to use a thicker plate/pipe as the raw material since thinning is expected at the extrados.

Query:-
I don't have experience of using SIF's different from ASME B31.3 even though I know that fittings which I am using are thicker than required.
So should I just ignore B31.3 warnings considering that Code calculations are conservative enough to ignore such warnings.

Thanks