Answer: 

According to the ASME VIII Div.1 the minimum thickness shall be the greater thickness as given by the circumferential stress UG-27(c)(1) or longitudinal stress (c)(2).
The thickness due to the circumferential stress is always the greatest (see below) consequently APV uses only the first formula (NOTE: in Div.2 there is only one formula: circumferential stress).

To be strictly conform to the code, APV should print out the both formulas but this will not change the result.

A new enhancement has been logged: 

Enhancement 184810:Report both wall thickness results from Circ. Stress and Long. Stress Eq.