Franck L, I don't see any limitations noted. By "torque" I assume you mean bending imposed on the tubesheet.
I don't have a detailed understanding of Part UHX, but I see definitions of and the use of the various diameters in various calculated terms, leading to calculations of shear and bending stress in the tubesheet. I see the calculations performed for the various loading conditions. I see that the worst case governs.
So, I'd say that the effects of the non-alignment of diameters is handled by complicated and voluminous calculations.
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand