Flange Leakage & Equivalent Pressure (Kellogg) Calculator
Verify ASME B16.5 flange pressure-temperature ratings under concurrent external bending moments and axial tension to prevent gasket joint blowouts.
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The Kellogg Equivalent Pressure Method
Piping flexibility analysis often reveals large external bending moments and axial forces acting on flanged joints at pump nozzles and vessel connections. The M.W. Kellogg equivalent pressure formula converts these external mechanical moments into an equivalent internal hydrostatic pressure $P_{eq}$ to verify against ASME B16.5 pressure-temperature rating limits.
Kellogg Formula
P_eq = P + (16 · M) / (π · G³) + (4 · F_a) / (π · G²)
Where $G$ is the gasket reaction diameter, $M$ is resultant bending moment (in-lb), and $F_a$ is external axial tensile force (lbf). If $P_{eq} le P_{allow}$, the flange bolting and gasket maintain seating stress without leaking.