Why nozzle opening reinforcement formulas are different in AutoPIPE Vessel compared to ASME Section VIII Div. 1?
ASME Section VIII Div. 1, Fig UG-37.1 gives details only for nozzle opening in radial direction. We have to consider additional parameters for inclined and offset nozzles.
Formula given in ASME Section VIII Div. 1 for Area available in shell (A1) includes area at both side of nozzle center line. But AutoPIPE Vessel software calculates area available on both side of the nozzle center line separately because Area A1 can be different at both sides based on available length.
After calculating areas separately on both sides, finally adds them up to get the final area available. Hence software considers radius instead of diameter and still aligned with the code.
Refer first page of Isolated Openings sections (Attached below for reference) for more detailed image and notations like L1, α and β.
Refer below example, only for your reference only.
Bentley LEARN Server