pmipmbok,
2.2.5.2 (2006)states that fillet welds between parts...at an angle between 80-100 degrees, shop drawings shall show fillet weld leg size.
Figure 3.11 details prequalified skewed T-joints from 60 to 135 degrees. The fillet weld between 80-100 degrees would apply. A T-Joint is a 90 degree connection
3.9.1 doesn't exclude the T-joint it only gives limitations on the lap joint Fig. 2.1 and min. lap in Fig. 2.4
3.9.3 Skewed T-Joints falls under 3.9 Fillet Weld Requirements
Hope that makes sense. IMO the T-joint fillet weld is within the prequalified WPS requirements.