A serious calculator
for preliminary lug design.
Single-plate lifting lugs and padeyes — sized in seconds, with transparent assumptions, traceable sources, governing-check logic, and a printable report you can send to a colleague. Not a replacement for FEA. Not pretending to be.
Every active check is guarded by a hand-computed benchmark derived from the published clause equations.
Preliminary design, done properly.
The tool covers the checks you'd do by hand in the first pass of a lug design — faster, with clearer traceability and a report you can actually share.
Every implemented check prints the assumptions it relies on — load in plane, linear-elastic, user-supplied allowables, single-plate geometry. No hidden factors.
Every check links to a source reference with edition and clause number. Mechanics identities are labelled public-domain; ASME BTH-1-2020, EN 1993-1-8:2005 §3.13 and DNV-ST-N001:2020 §16 are each guarded by a hand-computed benchmark.
All applicable checks run on every input change; the governing failure mode is selected from the methodology you pick, and the other families appear alongside as cross-checks.
Edge distance below d_hole, large lifting angle, unusual pin-hole clearance, offshore scenario — out-of-scope cases are flagged automatically with a recommendation to use a detailed method or FEA.
Structured report with project metadata, inputs summary, assumptions, result table, source traceability, timestamp, and revision — not a screenshot.
Inputs live in the URL and in your browser. Share a link, reload, hand it off. The app doesn't need to own your data.
We don't claim "all standards supported." We tell you exactly which clauses are implemented, which route drives the governing utilisation, and what's out of scope.
Net-section tension, double-plane shear-out, pin bearing, pin double shear, and a full angle-aware fillet weld group (throat resultant + von Mises). Classical identities used as cross-checks and for the live report.
Pin-connected plate static strength (§3-3.3.1 – §3-3.3.4) and fillet-weld allowable (§3-3.4.3) extended to a combined-stress interpretation, with Design Category Nd and static/rotating service-class bearing allowables.
Pin-plate geometry (Table 3.9), pin shear and plate bearing (Table 3.10), pin bending + combined shear/bending (Figure 3.11, Table 3.10). New: directional and simplified fillet-weld methods on the lug base weld group (§4.5.3.2 / §4.5.3.3), β_w and γ_M2 user-editable.
Fillet weld nominal strength with the directional increase and ASD . Runs alongside the mechanics weld checks; uses the same electrode value as the BTH-1 allowable.
Weld-symbol convention used by the schematic: the fillet leg is shown on the symbol, closed-perimeter groups get the weld-all-around circle, and the schematic side view carries the throat dimension.
Dynamic amplification and skew-load factors from Section 16. Applied on the demand side of every resistance check — including all weld checks — when the DNV route is selected; project values can override the defaults.
A report that reads like engineering, not like marketing.
Structured sections: project metadata, inputs summary, assumptions, result table with demand / capacity / utilisation per check, governing check, warnings, source traceability, and a timestamped revision note. PDF export is rendered as structured pages — not a blurry screenshot.
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Calculators have aged badly. This one doesn't.
Honest answers, before you trust the number.
No. The tool is for preliminary sizing and quick verification within its supported scope. It does not replace a full engineering review, specialist lift procedures, or FEA where the geometry or loading demands it. The app says so in the UI and on the report.
Four methodology routes are active. The public-domain mechanics route uses the classical identities (net-section tension, double-plane shear-out, pin bearing, pin double shear, fillet weld throat) against your allowables. The ASME BTH-1-2020 route implements the pin-connected plate checks of §3-3.3 and the fillet-weld allowable of §3-3.4.3. The EN 1993-1-8:2005 route implements the §3.13 pin-connection geometry and resistances. The DNV-ST-N001:2020 route adds the Section 16 dynamic amplification and skew-load factors on top of the resistance checks.
Each code route ships with at least one hand-computed benchmark derived from the clause equations and any worked example in the standard. Every time the site is built, the calculator is re-run against those benchmarks. If a computed value drifts outside the stated tolerance, the release is stopped. You can see the full table on the validation page.
Automatic rules catch cases like edge distance below d_hole, lifting angles above 30°, large pin-hole clearance, offshore scenarios, and high utilisation. Each fires an explicit warning on-screen and in the report, and the overall status becomes indeterminate rather than a misleading pass.
No. Inputs live in your browser and in the URL. There is no account and no database in v1. You can share a calculation by copying the URL.
No. The report is a structured, printable summary of the engineering decisions you entered and the transparent checks performed against your allowables. It is a communication artefact, not a certification.