Plan cathodic protection materials with confidence. Choose alloy capacity, utilization, and efficiency. See recommended anode count and reporting tools for projects large small sites.
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This calculator estimates the sacrificial anode mass needed to supply a design protection current for a chosen design life.
Where:
Practical note: Current density, coating breakdown, utilization, and current output limits depend heavily on environment, installation, and specifications. Treat presets as starting points.
| Scenario | Area (m^2) | Current Density (mA/m^2) | Breakdown | Life (years) | Capacity (Ah/kg) | Efficiency (%) | Utilization | Safety | Result Mass (kg) | Suggested Anodes |
|---|---|---|---|---|---|---|---|---|---|---|
| Coated steel, moderate soil | 50 | 10 | 0.20 | 20 | 780 | 90 | 0.85 | 1.10 | ~2.57 | 1 × 10 kg |
| Higher breakdown, longer life | 120 | 15 | 0.35 | 30 | 2000 | 90 | 0.85 | 1.20 | ~5.18 | 2 × 10 kg |
| Conservative current limit per anode | 200 | 12 | 0.30 | 25 | 1200 | 50 | 0.80 | 1.25 | ~13.69 | 7 × 2 A limit |
Examples are illustrative; adjust to your specification and environment.
Buried steel, sheet piles, ground anchors, tanks, and temporary works can lose metal quickly when soils are aggressive or coatings are damaged. Sacrificial anodes supply a protective current that shifts the steel potential and slows corrosion. Correct mass selection reduces maintenance visits, avoids premature replacements, and supports predictable project schedules.
Area is often underestimated when weld seams, cut edges, fasteners, and connections are ignored. Use drawings, takeoffs, and field measurements to capture the real wetted or buried surface. When in doubt, apply a small uplift to the area rather than forcing a high safety factor later.
Current density depends on moisture, resistivity, oxygen availability, and coating quality. Lower values fit well-coated structures in stable soils, while higher values are common for damaged coatings, tidal exposure, or variable backfill. Keep units consistent; the calculator converts to a common basis to reduce mistakes.
Coating breakdown is a planning fraction that represents the portion of the surface expected to become exposed over time. For robust coatings, a modest breakdown may be reasonable; for temporary coatings, field joints, or abrasion risk, increase it. This factor directly scales the protection current and the resulting charge requirement.
Capacity (Ah/kg) is how much charge a kilogram of alloy can deliver, while efficiency represents how much of that charge is practically realized. Utilization reflects the fraction of anode mass that can be consumed before it becomes ineffective. Using manufacturer data is best; presets are only starting points for scoping.
Design life converts current into total ampere-hours over years of exposure. Safety factor covers uncertainties such as seasonal moisture swings, coating damage during installation, and variability in backfill. A moderate safety factor paired with careful inputs is usually more transparent than extreme multipliers.
Mass alone does not ensure performance if too few anodes are installed. The calculator provides a count check based on unit anode mass and a conservative current limit per anode, helping spread current distribution. Use this as a planning signal; final spacing should match drawings and field constraints.
Record the input assumptions, conversions, and outputs so reviewers can reproduce decisions. The CSV and PDF reports support submittals, toolbox talks, and change control. Always cross-check against project specifications, environmental surveys, and supplier datasheets before procurement.
It is the planned fraction of surface expected to be exposed over time. A higher value increases required current and anode mass, reflecting coating damage, field joints, abrasion, or aging effects.
Select based on environment and specifications. Zinc and aluminum are common in many soils and waters, while magnesium is often used where higher driving voltage is needed. Confirm with supplier recommendations and standards.
Not all anode mass can be consumed usefully. Geometry changes, passivation, or core exposure can limit performance. Utilization represents the practical fraction available, so it lowers effective ampere-hour delivery per kilogram.
Use project guidance or corrosion surveys when available. As a screening step, consider coating quality, soil resistivity, moisture, and oxygen access. More aggressive environments generally require higher current density values.
It is a conservative limit for how much current one anode can deliver without poor distribution or rapid depletion. Using a lower limit increases anode count, improving current spread and redundancy.
Yes, for planning. Set design life to the expected exposure duration and adjust breakdown for handling damage. Final design should consider retrieval, electrical continuity, and installation practicality on site.
Mass is proportional to current and life, and current depends on area, density, and breakdown. Small shifts in those drivers compound over years. Document assumptions and use sensitivity checks for critical scopes.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.