Estimate sacrificial-anode consumption, required anode mass and service life from protection current, operating time, electrochemical capacity and anode utilization.
How the calculation works
Charge demand
Electrical charge required = protection current × operating time.
Theoretical anode mass
Theoretical mass = required ampere-hours ÷ electrochemical capacity.
Practical anode mass
Practical mass is increased to account for the selected anode utilization factor.
Design mass
The design mass adds the selected safety allowance to the practical mass.
Anode life
Life is estimated from available anode mass, utilization, electrochemical capacity and protection current.
The calculator uses electrochemical capacity in Ah/kg. For engineering design, use the capacity and utilization values applicable to the specific anode alloy and operating environment.
Sacrificial anode factors
- Protection current: higher current demand consumes anodes faster.
- Operating time: longer protection periods require more anode capacity.
- Anode alloy: zinc, aluminum and magnesium systems have different electrochemical performance.
- Utilization: practical anode replacement normally occurs before every last portion of metal is consumed.
- Environment: electrolyte chemistry, temperature, flow and salinity can affect anode performance.
- Current distribution: actual protection current may not remain constant over the entire service period.
- Safety allowance: additional capacity can provide design margin, but should follow the applicable engineering basis.
This is an estimation tool, not a complete cathodic-protection design. Actual anode selection and quantity should account for current-density requirements, coating condition, electrolyte/environment, anode spacing, electrical continuity and applicable standards.
Frequently Asked Questions
How is sacrificial anode consumption calculated?
Calculate the required ampere-hours from current and time, then divide by the anode's electrochemical capacity and adjust for practical utilization.
What is Ah/kg?
Ah/kg means ampere-hours of electrical charge delivered per kilogram of anode material. It is a useful measure for estimating electrochemical consumption.
Can I calculate zinc anode consumption?
Yes. Select zinc and enter the appropriate electrochemical capacity for the zinc anode system being evaluated.
Can I calculate aluminum anode consumption?
Yes. Select aluminum alloy and use the capacity applicable to the specific alloy and design basis.
Can I calculate magnesium anode consumption?
Yes. Magnesium can be selected, with its electrochemical capacity used for the estimate.
Why does anode utilization matter?
Anodes are generally not designed around complete physical disappearance. Utilization accounts for the portion of anode mass considered practically usable.
Can this calculate how long an existing anode will last?
Yes. Enter the available anode mass and current demand. The calculator estimates service life based on the selected electrochemical capacity and utilization.
Is this suitable for final cathodic-protection design?
No. Final design requires project-specific engineering analysis and applicable standards. This calculator is intended for estimation and preliminary planning.