SAMPLE
Piping Toolset — Calculation Report
generated by calc-core · 2026-07-21
ProjectSample Project — Demonstration Only Job No.SAMPLE-001 Client—
CalculationFlange Equivalent Pressure Calculator (Kellogg Method) Calc byPiping Toolset (calc-core) Checked byUNCHECKED — sample
Date2026-07-21 Rev0 BasisKellogg equivalent-pressure flange check

1 · Design inputs

NPS 6 Class 600 flanged joint on a hot line. Design pressure 500 psi, the flexibility analysis reports 50,000 in·lb resultant bending moment and 2,000 lbf axial tension at the flange. Gasket reaction diameter G = 6 in; the applicable B16.5 table gives a rating of 1,975 psi at the design temperature.

Design pressure P500psi
Axial force F2,000lbf
Bending moment M50,000in·lb
Gasket reaction diameter G6in
Rated pressure (user-supplied)1,975psi

2 · Method

The Kellogg equivalent-pressure method replaces the external loads with the internal pressure that would produce the same net hydrostatic end force and the same flange moment about the gasket reaction circle:

Pe = P + 16·|M| / (π·G3) + 4·F / (π·G2)

utilization = Pe / Prated  —  PASS when Pe ≤ Prated

where P is the internal design gauge pressure, M the resultant external bending moment on the joint, F the external axial force (tension positive), G the gasket reaction diameter, and Prated the flange pressure–temperature rating at the design temperature. The moment is taken as an absolute value — direction does not relieve the joint. A compressive (negative) F reduces Pe, so the calculator warns when that happens; the tensile case must then be screened separately.

3 · Calculation

  1. Moment term: 16·50,000 / (π·63) = 800,000 / (π·216) = 800,000 / 678.584 = 1178.926 psi.
  2. Force term: 4·2,000 / (π·62) = 8,000 / (π·36) = 8,000 / 113.097 = 70.736 psi.
  3. Equivalent pressure: Pe = 500 + 1178.92550 + 70.73553 = 1749.661 psi (the two terms are displayed rounded to three decimals, but Pe is formed from the unrounded values).
  4. Utilization: 1749.661 / 1,975 = 0.8859 — below 1.0, so the joint passes the screen.
  5. Sensitivity: with the same loads against a 1,500 psi rating the utilization becomes 1.1664 and the joint fails — the external moment alone consumes more of the rating than the design pressure does.

4 · Results PASS

Moment term 16M/(πG³)1178.926psi
Force term 4F/(πG²)70.736psi
Pe — equivalent pressure1749.661psi
Utilization Pe/Prated0.8859—

5 · Verification statement

The result values above are locked as fixture flange-equivalent-pressure.json, case “P=500, M=50000 in·lb, F=2000 lb, G=6 in vs rated 1975 -> pass”, tolerance 0.001, in the calc-core continuous verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are user-supplied inputs; citations: ASME B16.5, Pipe Flanges and Flanged Fittings — ¶2.1, pressure–temperature ratings (rating value user-supplied, not embedded). · ASME B16.47, Large Diameter Steel Flanges — ¶2.1 ratings, for NPS 26 and larger joints. · ASME BPVC Section VIII Division 1, Mandatory Appendix 2 — ¶2-3, gasket reaction diameter G and effective gasket seating width. · ASME B31.3, Process Piping — ¶303 ratings of listed components and ¶304.5.1 flanges; ¶319.4.1 for the flexibility analysis that produces M and F. · M.W. Kellogg, Design of Piping Systems — equivalent-pressure method (public-domain engineering method; not an ASME Code equation).

SAMPLE REPORT — auto-generated from a verification fixture to show the report format. Not a project calculation. ⚠ Engineering-aid tool. Public code equations; allowable-stress and factor data are user-supplied. Results MUST be independently verified and reviewed by a qualified/licensed engineer before any design, fabrication, or operation decision.