Pressure Vessels — validation & limitations

What it calculates

• ASME VIII Div.1 UG-27 minimum wall thickness and back-calculated MAWP for cylindrical shells, with automatic switchover to the Mandatory Appendix 1-2 thick-wall equation above 0.385·S·E
• Lamé hoop and radial stress at every wall ratio (40-point through-wall profile with von Mises and maximum shear); longitudinal stress in the conservative membrane form below t/R = 0.10 and the exact closed-end value above
• All four ASME head types: ellipsoidal 2:1 (UG-32d), hemispherical (UG-32f), torispherical with M-factor (UG-32e), and flat plate (UG-34) with attachment-factor selector
• Nozzle reinforcement screening estimate (UG-45/UG-37 t_n_min) and ASME B16.5-2017 Class 150–2500 flange pressure ratings from −29 to 538 °C
• Creep utilisation (σ_θ / σ_creep) vs temperature and Miner's-rule thermal fatigue damage for four materials (carbon steel, 304 SS, 316 SS, Cr-Mo steel)
• Four built-in material allowables (SA-516-70, SS-304, SS-316L, Al-5083-O — the Al-5083 value is derived from the Code room-temperature criterion on ASTM B209 minimum properties for the O temper, not read from II-D, and this is stated in the results) plus a custom-allowable entry — each S is a single tabulated constant, NOT derated for temperature: above 300 °C for carbon steel (40 °C for the stainless and aluminium entries) the verdict reads CHECK until a temperature-derated allowable from ASME Sec. II-D is entered, and an unconfirmed full-RT joint efficiency (1.00) reads CHECK too

Standards this tool applies

• ASME VIII — ASME VIII Div.1 design-by-rule checks: UG-27 cylinder wall, MAWP, Lamé stresses, UG-32/UG-34 heads, nozzle screening (UG-45 + partial UG-37), B16.5 flange ratings.

Validation evidence — independent reference cases (1)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

• UG-27 shell, UG-32(d) 2:1 head thickness, MAWP, hoop SF

  Agrees

  Source: ASME BPVC Section VIII Div.1 UG-27(c)(1), UG-32(d), UG-32(e), UG-25(c); E. F. Megyesy, Pressure Vessel Handbook, shell/head examples; hand derivation

  Inputs: P 100 psi, R 48 in, S 17500 psi, E 0.85, CA 0.125 in, plate 0.5 in; torispherical case P 1 MPa, L 1500, r 90, S 138 MPa

  Quantity	Reference value	Tolerance
  shell t_min (mm)	8.250928	0.01 % relative
  2:1 head t_min (mm)	8.223175	0.01 % relative
  MAWP shell (MPa)	0.7954461	0.01 % relative
  torispherical head t_min (mm)	9.6299169	0.01 % relative

  tests/golden/REF-pressure-ug27-shell-ellipsoidal.golden.test.ts

Limitations

Not checked by this tool

• External-pressure (vacuum) buckling of the shell and heads (UG-28) — Never computed (a declared vacuum caps the verdict at REVIEW); check per ASME VIII Div. 1 UG-28 / UG-33
• Wind, seismic, support (saddle, skirt, leg) and local nozzle / attachment loads — Not combined; check the supports (e.g. Zick for saddles) and piping loads on nozzles (WRC 537 / 297)
• Temperature-derated allowable (ASME II-D) and MDMT / impact testing (UCS-66) — Built-in S is a room-temperature constant (hot service reads CHECK; enter the II-D value as Custom); the MDMT exemption is not determined
• Full UG-37 reinforcement and flanges other than B16.5 Group 1.1 (Appendix 2) — The nozzle panel is a conservative screen on Group 1.1 ratings only; do the full UG-37 calculation and design other flanges per Appendix 2
• Conical sections and cone-to-cylinder junctions — Not modelled; calculate per ASME VIII Div. 1 UG-32(g) and Appendix 1-5
• Cyclic pressure and weld fatigue — Static design only; screen for fatigue per ASME VIII Div. 2 Part 5 (5.5) or EN 13445-3 cl. 17/18 for start-stop or pulsating service
• UG-16(b) minimum thickness of shells and heads — No Code floor is applied to a very thin wall; confirm the UG-16(b) minimum (about 1.5 mm, exclusive of CA) and its exemptions
• Torispherical head limits beyond the knuckle proportions (crown vs skirt OD, App. 1-4) — r >= 0.06*L and r >= 3t cap the verdict at CHECK; crown radius vs skirt OD and the Appendix 1-4 rules are not checked