There is a misconception among some Certificate Holders that small nozzles and fittings are exempt from UG-45 (or UG-44) calculations. Small openings that comply with the requirements of UG-36(c)(3)(a) are only exempt from reinforcement calculations and UW-15 weld strength calculations.
All nozzles are required to have UG-45 nozzle neck calculations and B16.9 and B16.11 fittings are required to be calculated as straight seamless pipe per UG-44.