Currently, AutoPIPE calculates the gasket seating width (N) using the gasket outside diameter (OD) and inside diameter (ID), N=(Gasket OD-Gasket ID)/2.

As per ASME Section VIII (Sketch 1a), the gasket seating width should be calculated based on the actual seating contact area, not simply the gasket OD.

Correct formulation:

N=(min⁡(R, OD) − max⁡(B2, ID))/2

Where:

• R = Raised face outside diameter (actual seating diameter)

• OD = Gasket outer diameter (may represent centering ring)

• ID = Gasket inside diameter

• B2 = Effective inner seating boundary

For raised-face flanges, R should typically govern, not OD.