Does this worksheet calculate pressure-vessel wall thickness to ASME or EN 13445?

No. It deliberately does not reproduce licensed code formulas. It only checks arithmetic between thickness values already established and documented by an approved code calculation.

What is documented calculation thickness?

It is the thickness value taken from the identified approved calculation at the stated component location and basis. Its exact definition is controlled by that calculation and governing code.

What belongs in additive allowance?

Only thickness that the controlled calculation explicitly instructs you to add arithmetically to the documented calculation thickness. Do not invent a generic corrosion or wear allowance.

What is minimum credited thickness?

It is the minimum thickness the approved calculation permits you to credit at the same location and basis after every applicable non-additive deduction or tolerance has been handled by the controlled process.

Does an above or equal comparison prove code compliance?

No. The relation is only arithmetic. Code applicability, inputs, formulas, load cases, materials, fabrication, examination, testing, jurisdiction and approval remain outside this worksheet.

Evidence-controlled arithmetic · not code sizing

Controlled Pressure-Vessel Thickness Record Comparator

Compare a thickness already established by an approved licensed-code calculation, plus only its explicitly authorized additive allowances, with a minimum credited thickness on the same documented basis.

No ASME/EN formulas reproducedExact mm ↔ in routeNo compliance verdict

Thickness unit

Governing record basis

Component / calculation location

Approved calculation / document reference

Documented calculation thickness t_calc (mm)

Authorized additive allowance c_add (mm)

Minimum credited thickness t_credit (mm)

I confirm that t_calc, c_add and t_credit come from the identified approved calculation/process for the same component location, edition, geometry basis and units; c_add contains only explicitly additive items; t_credit already handles every applicable non-additive tolerance/deduction as required by that process; and I will not treat this arithmetic relation as code compliance.

Arithmetic comparison

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Documented arithmetic total tcalc + cadd

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Minimum credited thickness

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Arithmetic margin tcredit − total

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Arithmetic ratio tcredit / total

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Not code acceptance: “above”, “equal” or “below” describes only the entered numbers. It does not validate their definitions, the original code calculation, nominal plate selection, tolerances, load cases, fabrication, examination, test or legal conformity.

Same-basis record comparison

t_{documented,total} = t_calc + c_add
margin = t_credit − t_{documented,total}
ratio = t_credit / t_{documented,total}

All three thickness inputs must refer to the same physical component location and compatible thickness definition. The worksheet converts inches to millimetres internally with exactly 1 in = 25.4 mm, performs addition/subtraction/division, and returns the selected display unit.

A positive margin means only that the entered credited value is numerically above the entered arithmetic total; zero means equal; a negative margin means below. No safety factor, allowable stress, joint coefficient, head coefficient, pressure formula or code acceptance rule is applied.

Do not substitute nominal plate thickness blindly: t_credit is the minimum thickness the approved process permits you to credit at the comparison location and basis. Nominal thickness may require mill tolerance, forming thinning, corrosion/erosion treatment or other deductions that this page cannot infer.

The former page claimed minimum shell and head thicknesses to EN 13445 and ASME Section VIII from pressure, outside diameter, a fixed material value, a generic weld factor and corrosion allowance. That claim was not supportable.

Former component	Confirmed problem
Design temperature	Collected but never used. Hard-coded allowable stresses therefore did not change with temperature.
Material presets	Fixed values were shown without a verified edition, product form, temperature row, notes or code-source traceability; ASME SA material labels were also offered under the EN route.
Joint / weld factors	Generic 1.0, 0.85 and 0.7 choices were applied to both code systems without verified joint category, examination scope or licensed rule.
Cylindrical formula	The displayed ASME inner-radius equation differed from the outside-diameter equation executed by JavaScript. The worked example used another radius approximation while the default route was EN.
Heads	Hemispherical and ellipsoidal equations were labelled code formulas while runtime comments called them approximations or simplifications. Flat-head coefficients 0.33 and 0.35 were hard-coded as “typical” without geometry/attachment scope.
Corrosion and plate recommendation	Universal service allowances and “use 12 mm plate minimum” ignored the controlled corrosion basis, negative tolerance, forming, other loads and code-specific requirements.

Changing one coefficient would conceal rather than fix these root causes. The unsupported formula engine, presets, automatic results and code-compliance language were removed.

This list is a scope reminder, not a substitute for either code. The responsible approved calculation must determine what applies, including:

jurisdiction, exact governing code/edition/addenda and component scope;
design, operating, test and external pressures; temperatures and coincident load cases;
component geometry, diameter/thickness convention, heads, openings, nozzles, supports and discontinuities;
material specification, product form, temperature-dependent allowable basis and degradation mechanisms;
joint category, weld details, examination extent, applicable coefficient and fabrication route;
corrosion/erosion allowance, design life, negative material tolerance, forming thinning and credited minimum thickness;
external-pressure stability, local loads, wind/seismic/dead weight, thermal effects, fatigue, creep, fracture and cyclic service as applicable;
reinforcement, inspection, nondestructive examination, pressure testing, overpressure protection, documentation and authorized approval.

Definitions control: whether an allowance is added to a calculated thickness, deducted from an available thickness, embedded elsewhere or handled by another rule cannot be decided by this page. Follow the licensed code and the approved project calculation exactly.

ASME BPVC Section VIII, Division 1

The official ASME BPVC.VIII.1-2025 product page describes requirements for design, fabrication, inspection, testing and certification of vessels within its scope, with material/fabrication requirements and mandatory and nonmandatory appendices. This public scope confirms why a few generic equations cannot establish conformity; detailed rules require authorized access.

EN 13445-3

The official national-standards-body page for NBN EN 13445-3:2026 identifies it as active from 2 July 2026, replacing NBN EN 13445-3:2021+A1:2026. Its scope is design of unfired pressure vessels covered by EN 13445-1:2026 and constructed of steels under EN 13445-2:2026. Detailed rules remain licensed, and the applicable national adoption/jurisdiction must be confirmed.

Length conversion

NIST SP 811 Appendix B.8 lists 1 inch = 0.0254 metre and marks exact factors in bold. Therefore 1 in = 25.4 mm and the official unit check 0.5 in = 12.7 mm is exact.

Sources and lifecycle status accessed 13 July 2026. No ASME/EN clause number, table value or formula is asserted without the licensed text.

No. The former unsupported formula engine was removed. Enter only values already established by the identified approved licensed-code calculation.

Only items the controlled calculation explicitly requires to be added arithmetically at the same component location and thickness basis. Zero is valid. Do not insert generic corrosion values.

Only if the approved process explicitly permits that exact value to be credited after all applicable tolerance,forming and other deductions. This page cannot make that determination.

No. It is only the relation between three entered thickness records. The code calculation and every governing design,fabrication,inspection,test and approval requirement remain external.

Their correct values depend on exact code edition,material/product form,temperature,joint/examination scope and other licensed rules. Generic presets created false certainty.