User Manual

Introduction

The GCS Oman Tools & Calculators is a free, browser-based set of 38 calculators across 10 HSE domains: lifting & rigging, LEEA inspection, LEEA hardware SWL, risk assessment, gas safety, electrical safety, work at height, fire safety, driving safety, and ATEX / hazardous areas. The site is built and maintained by Gulf Calibration & Safety Services in Muscat, Oman.

Each calculator is designed for training — it implements simplified or commonly-taught versions of recognised standards: ASME B30, ISO 31000 / 4309, IEEE 1584-2018, NFPA 10 / 13 / 70E / 291 / 1404, OSHA 1910 / 1926, IEC 60529 / 60079, EN 818 / 13889 / 13155 / 12811 / 131, BS 4278, LEEA COPSURE, LOLER 1998, IOGP 365 / 376. Engineered decisions must always be made by a competent person against the full current edition of the applicable standard.

Three of the ten domains follow the workflow of a Lifting Equipment Engineers Association inspector: Lifting & Rigging for planning, LEEA Inspection for in-service condition checks (LOLER, wire rope, chain, hooks), and LEEA Hardware SWL for accessory selection (eyebolts, shackles, lifters, clamps).

How the tools work

1. Open a category page from the navigation.
2. Adjust inputs — sliders, text fields, segmented controls. Most tools recalculate instantly as you type.
3. Read the result panel on the right (or below on small screens). A coloured status pill summarises whether the situation is safe / caution / danger / extreme.
4. Hover the small i circles for definitions of technical terms.
5. Use the action bar at the bottom of each tool for export (PDF, CSV, JSON), print, or reset.

Print, PDF, CSV, JSON

Light & dark themes

Use the sun/moon icon in the header to toggle dark mode. Your preference is saved locally and persists across pages and visits. The site also honours your system's prefers-color-scheme setting on first visit.

Searching

Hit Ctrl + K (Windows / Linux) or ⌘ + K (macOS) — or press / when not focused on a field — to open the instant search modal. Type a tool name, formula keyword, gas, vehicle type, or a recognised standard (e.g. NFPA 13, IEEE 1584, ASME B30). Use ↑/↓ arrows to navigate, ↵ to open. Or visit the dedicated /search results page.

Privacy & data

All calculations run entirely in your browser. No inputs, results, or exports are transmitted to GCS Oman or third parties. The only data we collect is anonymous traffic statistics (Google Analytics 4 with IP anonymisation), and only after you accept analytics cookies. See the full privacy policy.

Disclaimer

Lifting & Rigging

#1Sling Load Calculator Open →

Purpose: compute the tension on each sling leg given the load, number of legs, sling angle and hitch type. Confirms whether a sling's stamped Working Load Limit (WLL) is sufficient.

Formula: T = (W × HitchFactor) / (N × sin θ) with θ measured from horizontal. Hitch factors: vertical 1.00, choker 1.33, basket 0.50.

Inputs: total load weight (kg/t/lb) · number of legs (1–4) · sling angle (15–90°) · hitch type · WLL per leg (optional).

Reference: ASME B30.9 (slings). Per ASME, 3- and 4-leg bridles are conservatively designed assuming only 2 legs share the load.

#2Centre of Gravity Estimator Open →

Purpose: compute the combined centre of gravity (X, Y, Z) of a load made of multiple components. Useful to position lift points and avoid tipping during multi-point lifts.

Formula: mass-weighted average per axis: X̄ = Σ(mᵢ·xᵢ) / Σmᵢ.

Inputs: add components by name with mass (kg) and X/Y/Z coordinates (m). Use the preset buttons (Pipe, Skid, Vessel) for typical components.

#18Crane Load Chart Estimator Open →

Purpose: indicative allowable load for the chosen crane class, boom length, operating radius, setup and quadrant. Always cross-check against the manufacturer's actual load chart.

Inputs: crane size class (25–500 t) · boom length (m) · operating radius (m) · setup (outriggers / on rubber) · quadrant (over rear / side / front) · planned load (kg).

#26Sling Mode Factor (LEEA) Open →

Purpose: formal LEEA Mode Factor (M) lookup that returns the effective WLL of a sling system from the rated single-leg WLL. Replaces the simplified hitch factors of tool #1 with the recognised LEEA terminology used on data plates.

Formula: Effective WLL = WLL_single × M × cos β. Single 1.0, choke 0.8, basket 2.0, parallel 2.0, U-lift 1.0, two-leg 2.0, three/four-leg 2.0 (LEEA conservative — only 2 legs assumed sharing). β is each leg's angle from vertical; LEEA caps β at 60° (120° included) for routine lifts.

At rated effective WLL each leg sees: T_leg = WLL × M / N — i.e. exactly its single-leg rating.

Reference: LEEA COPSURE 1.6, EN 13414-1.

#27Lift Plan Categorisation Open →

Purpose: score-based classifier returning the lift category (Cat 1 routine / Cat 2 non-routine / Cat 3 critical) with the documentation, approval level and pre-lift requirements that follow from each.

Inputs: load weight, crane chart capacity at planned config, lift mode (single / tandem / multi), personnel exposure, visibility, environment and load criticality. The score (0–20) drives the category boundary.

Reference: LEEA Lift Planning guidance; IOGP 376. Site rules may override — defer to your Appointed Person.

#28D/d Ratio Calculator Open →

Purpose: compares the bend radius (D) of a sheave, drum, shackle pin or plate edge against the wire rope / chain diameter (d). Below LEEA-recommended ratios, rope efficiency drops and the WLL must be derated. The chart shows efficiency vs D/d from 1 to 40.

Recommended minima: hoist drums & sheaves D/d ≥ 18 · sling around shackle pin ≥ 6 · sling around a plate edge ≥ 1 (with softener / thimble).

Efficiency model: η ≈ 1 − 0.45 / √(D/d), capped at 95% upper, 50% lower — matches LEEA published table values within ± 2%.

Reference: LEEA COPSURE 1.4 / 4.6, ISO 4308.

LEEA Inspection

Tools used by LEEA-trained inspectors during the in-service check or thorough examination of lifting equipment. None of these tools issue an Examination Certificate — they help a competent person reach a defensible discard / monitor / pass decision faster, with the binding criterion clearly recorded.

#29LOLER Thorough Examination Scheduler Open →

Purpose: compute the next required thorough-examination date for a piece of lifting equipment based on the LOLER 1998 statutory interval, the equipment type, and any exceptional circumstance during the period.

Intervals: 6 months for equipment used to lift people and for lifting accessories · 12 months for other lifting equipment. Out-of-cycle exam required after overload / shock load, modification, ≥ 6 months idle, or harsh-environment exposure.

Reference: LOLER 1998 reg. 9, LEEA COP-LOLER. A written scheme of examination prepared by a competent person can vary the default intervals.

#30Wire Rope Discard Criteria Open →

Purpose: screen a rope sample against the four LEEA inspection categories — broken wires (per 6d and 30d), diameter loss, corrosion grade and deformation. Returns discard / monitor / pass with the binding criterion.

Broken-wire limits (subset of ISO 4309 table for M-class service): 6×19, M3 — 6 in 6d / 12 in 30d · 6×36 IWRC, M3 — 8 in 6d / 16 in 30d · Rotation-resistant, M3 — 4 in 6d / 8 in 30d.

Other absolute discards: diameter loss ≥ 10% (or ≥ 7% for some constructions), kink / dog-leg, basket distortion, birdcaging, strand protrusion, crushing, heat / arc damage, heavy corrosion (grade 3+).

Reference: ISO 4309:2017, LEEA COPSURE 4.

#31Chain Sling Discard Criteria Open →

Purpose: screen a grade T (8) or grade V (10) chain sling against the EN 818 / LEEA discard rules.

Cross-section wear: % = (1 − (d_meas / d_nom)²) × 100; mandatory discard at > 10%. Measure two perpendicular diameters at the link bearing surface and average.

Pitch elongation: measure 11 links inside-to-inside, divide by 11. Mandatory discard at > 5% above nominal pitch.

Other absolute discards: any cracks, twist / bend / opened links, damaged welds, heat or fire damage. Sharp nicks and heavy corrosion → monitor / repair.

Reference: EN 818-2 (grade 8) and EN 818-4 (grade 10), LEEA COPSURE 2.

#32Hook Throat-Opening Inspection Open →

Purpose: check a hook against the four LEEA inspection criteria — throat opening increase, saddle wear, twist, and latch operation.

Throat opening: % = (A' − A) / A × 100. Discard at > 5% for standard / clevis hooks · > 10% for self-locking hooks where the manufacturer permits.

Other discards: saddle / load-bearing wear > 10% · twist of the hook tip > 10° from plane · missing or damaged latch.

Reference: LEEA COPSURE 5, ASME B30.10.

LEEA Hardware SWL

Working-Load-Limit and selection tools for the most common lifting accessories. Each tool follows the relevant LEEA COPSURE chapter and the cited EN / BS / ASME standard. Outputs are working SWL values — manufacturer's data plate is always authoritative.

#33Eyebolt / Eyenut SWL Derating Open →

Purpose: derate the axial SWL of an eyebolt for off-axis loading and warn against prohibited configurations. Distinguishes standard (no collar), collared / shouldered, and dynamic (rotating swivel ring) eyebolts.

Standard (non-collared): axial pull only. Even small misalignment costs ~35% capacity. Lateral pull (90°) is prohibited.

Collared: BS 4278 angle-pull table — 0° = 100%, 30° = 50%, 45° = 30%, 60° = 20%, 90° = prohibited. Linearly interpolated between table points.

Dynamic ring: rated 100% at any angle (per manufacturer).

Reference: BS 4278, LEEA COPSURE 1.5.

#34Shackle SWL Lookup Open →

Purpose: look up the rated SWL of a D-shackle (chain) or bow / anchor shackle by body diameter and grade, then apply a side-loading derate.

Sizes: 6 mm (¼″) to 100 mm (4″). Grades: M (G4 — basic) × 0.5 · S (G6 — standard high-strength) × 1.0 · T (G8 — alloy steel) × 1.4.

Side-load: 0° = 100%, 45° = 70% (both shapes). Beyond 45°, D-shackles fall steeply (60° = 50%, > 60° prohibited); bow shackles tolerate to 90° = 50%.

Reference: EN 13889:2003, US Federal Specification RR-C-271, LEEA COPSURE 6.4.

#35Vacuum Lifter Capacity Open →

Purpose: compute the allowable mass for a vacuum lifter from the achieved vacuum level, total pad area, surface efficiency and safety factor.

Formula: F = ΔP × A_total; m_allowable = (F × η_surface) / (g × SF).

Surface efficiency η: smooth non-porous 1.00 · rough machined 0.70 · porous (concrete / wood) 0.35 · oily / contaminated 0.25.

Safety factor: 2 minimum routine · 3 public area / overhead · 4 EN 13155 personnel-exposure.

Reference: LEEA COPSURE 8, EN 13155.

#36Magnetic Lifter Derating Open →

Purpose: derate a permanent or electro-permanent magnetic lifter's rated SWL for the actual load — plate thickness, material grade, surface roughness / air gap, and shape factors all combine.

Combined factor: eff = SWL_rated × (t/t_ref) × M_mat × (1 − air) × M_shape × (3 / SF_user).

Material factors: low-carbon 1.00 · medium-carbon / cast iron 0.65 · high-carbon / hardened 0.50 · stainless / non-ferrous 0 (cannot be lifted).

Surface factors: polished 1.00 · smooth machined 0.90 · rough mill scale 0.75 · pitted / corroded 0.55 · visible gap > 0.2 mm 0.30.

Shape factors: flat 1.00 · curved sheet 0.70 · round bar / pipe 0.50 (point contact).

Safety factor: 3:1 is the EN 13155 baseline (already in the rated SWL); selecting 4:1 for personnel exposure applies an additional 0.75 reduction.

Reference: LEEA COPSURE 9, EN 13155.

#37Plate Clamp Working Load Open →

Purpose: selection check for vertical (and horizontal-rated) plate clamps. Verifies the plate falls inside the clamp's jaw thickness range, that the load is within the per-clamp WLL, and warns when the surface is painted or rusty.

Per-clamp share: 1 clamp carries 100% of load; 2 clamps each assumed to carry 100% of load (LEEA conservative). Plate must be lifted directly over its centre of gravity for single-clamp lifts.

Reference: LEEA COPSURE 16. Vertical clamps must NEVER be used horizontally — different tool.

#38Beam Clamp / Trolley Flange Check Open →

Purpose: verify a beam clamp, plain trolley or girder clamp against the actual beam — flange thickness range, flange width range, side-pull envelope and parallel vs taper compatibility.

Side-pull envelope: typical clamps allow up to 6° from vertical at full WLL. Beyond 6°, capacity drops 5% per degree (floored at 40%). Effective vertical pull F_eff = F / cos α.

Compatibility: most plain trolleys require parallel-flange beams (UB / W-section). RSJ / classic I-beams have tapered flanges and need a clamp specifically rated for them.

Reference: LEEA COPSURE 13, EN 13155.

Risk Assessment

#3Interactive Risk Matrix Open →

Purpose: click a cell on the 5×5 Likelihood × Severity grid to record a hazard and get an automatic Low / Medium / High / Extreme rating with the suggested hierarchy of controls.

Reference: ISO 31000, ANSI Z10. Site-specific definitions vary; defer to your HSE management system.

#4Hierarchy of Controls Scorer Open →

Purpose: drag the five control levels into priority order. The tool scores against the recognised order (Elimination → Substitution → Engineering → Administrative → PPE) and warns when PPE is placed above engineered controls.

#19Bowtie Threat–Control Viewer Open →

Purpose: build a simple bowtie around a top event with threats (left), consequences (right), preventive (P) and mitigative (M) controls. Used in major-accident hazard reviews and IOGP-style barrier analyses.

Inputs: top event description · threats list (one per line) · consequences list · preventive control list · mitigative control list. The diagram redraws live.

Gas Safety

#5Gas Unit Converter Open →

Purpose: convert between ppm, %LEL, mg/m³, %Volume for the most common industrial gases (H₂S, CH₄, CO, O₂, NH₃, propane, hydrogen) plus a custom gas option.

Maths: molar volume Vm = R·T / P (R = 8.314 L·kPa/(mol·K)). The default conditions are 25 °C, 101.325 kPa per NIOSH; override for hot-process or high-altitude conditions.

#6SCBA Duration Calculator Open →

Purpose: estimate the working duration and the safe-escape duration of a Self-Contained Breathing Apparatus.

Formula: [(P_cyl − P_res) × V_cyl / P_atm] / RMV where RMV scales with work intensity (light 30, moderate 40, heavy 60, max 85 L/min).

Reference: NFPA 1404 — 33% reserve for escape.

#7Confined Space Ventilation Calculator Open →

Purpose: compute the airflow needed to deliver the target air-changes-per-hour (ACH) for a confined space.

Formula: Q (m³/h) = V × ACH; Q (CFM) = Q (m³/h) × 0.5886.

Reference: OSHA 1910.146 typically calls for ≥ 20 ACH pre-entry; hot-work or H₂S work often requires 30–60 ACH.

#20TWA / STEL Exposure Calculator Open →

Purpose: sum exposure intervals during a shift and compare against the 8-h TWA and STEL for the selected gas.

Formula: TWA₈ = Σ(Cᵢ·tᵢ) / 8 h. STEL is checked against any 15-minute interval peak.

Electrical Safety

#8Arc Flash Boundary Calculator Open →

Purpose: simplified illustration of the arc-flash incident energy at a working distance and the boundary at 1.2 cal/cm² (onset of 2nd-degree burn). Suggests a NFPA 70E PPE category.

Reference: IEEE 1584-2018 (simplified) and NFPA 70E. Not a substitute for a stamped engineering study.

#9LOTO Step Sequencer Open →

Purpose: training drill — drag the eight Lockout/Tagout steps into the correct sequence and get scored. Steps follow OSHA 1910.147.

#21Cable Voltage Drop Calculator Open →

Purpose: compute voltage drop and percentage drop across a copper / aluminium cable run with temperature correction. Suggests the next size up if the configured limit (3% lighting / 5% power) is exceeded.

Formulas: single-phase V_d = 2·I·L·R/1000; three-phase V_d = √3·I·L·R·cos φ /1000.

Reference: IEC 60364 / NEC 215.

Work at Height

#10Fall Clearance Calculator Open →

Purpose: compute the required clearance below the anchor and compare against the available distance to the next lower level.

Formula: Required = Lanyard + Deceleration + Worker height + Harness stretch + Safety margin.

Reference: ANSI Z359, OSHA 1926.502.

#11Scaffold Load Calculator Open →

Purpose: compare planned scaffold load (workers + tools + materials) against the duty rating used.

Reference: OSHA 1926.451 (Light 25 psf, Medium 50 psf, Heavy 75 psf), EN 12811-1 (Class 1 = 75 kg/m² up to Class 6 = 600 kg/m²).

#22Ladder Angle (4:1) Calculator Open →

Purpose: set up an extension ladder at the recognised 1:4 ratio (~75°). Reports base setback, minimum length and required overlap above the landing.

Reference: OSHA 1926.1053 (≥ 0.9 m / 3 ft above landing; tied off if > 7.3 m), EN 131.

Fire Safety

#12Fire Extinguisher Selector Open →

Purpose: pick the correct extinguisher class for the fuel involved and warn against dangerous mismatches (e.g., water on a Class C electrical fire).

#13Muster Time Calculator Open →

Purpose: estimate full evacuation time from detection lag, walking distance, route flow capacity and crowd density. Compare against the site's emergency-response plan target.

Reference: NFPA 101 (~1.3 persons/m/s flow capacity at pinch points).

#23Hydrant Flow & Sprinkler Density Open →

Purpose: two practical fire-water tools side-by-side. Hydrant pitot test: Q = 29.83·C·d²·√P (gpm); sprinkler design: Q = density × area (NFPA 13).

Driving Safety

#14Stopping Distance Calculator Open →

Purpose: compute thinking + braking distance by speed, road surface friction (μ), gradient and load.

Formula: d_b = v² / (2·g·(μ + sin θ)) with thinking distance d_t = v·t_react.

#15Journey Risk Assessment Open →

Purpose: structured journey-risk score from distance, hours, weather, time of day, driver and vehicle. Recommends mitigations.

#24Convoy Spacing & 2-Second Rule Open →

Purpose: compute the safe spacing between convoy vehicles, total convoy length and recommended radio-check cadence.

Reference: IOGP 365 land transport safety. Time-gap rule: 2 s dry, 3 s wet, 4 s fog/HGV, 6 s towing.

ATEX / Hazardous Areas

#16IP Code Decoder Open →

Purpose: decode IP enclosure ratings (IP44, IP54, IP65, IP67, IP68…) — the first digit is solids/dust, the second is water.

Reference: IEC 60529.

#17Zone Classification Guide Open →

Purpose: indicative Zone 0 / 1 / 2 boundaries around typical leak sources (pumps, flanges, vents, road-tanker filling).

Reference: IEC 60079-10-1. Indicative only — site DSEAR / area-classification drawings govern.

#25Ex Equipment Marking Decoder Open →

Purpose: build and decode an Ex marking (e.g. II 2 G Ex db IIC T6 Gb) into Group, Category, EPL, gas group, temperature class, and verifies suitability for the chosen Zone.

Reference: IECEx / ATEX, IEC 60079-0.

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