CP Current Requirement Calculator
Pipeline engineers need rapid preliminary sizing for rectifiers and anode beds during the front-end design phase, specifically when applying the I = A * f_c * i_c formula and ISO 15589-2 degradation curves before committing to detailed surveys.
Final CP Current Demand, end of life (A)
Calculation based on: I = A * f_c * i_c incorporating coating breakdown factor f_c = a + bt per ISO 15589-2
Disclaimer: for preliminary estimation only, not a substitute for review by a qualified/licensed engineer.
How to Use This Tool
- Enter the total external surface area of the pipeline in square meters.
- Input the starting coating breakdown percentage and the expected annual increase rate.
- Set the design life in years along with your protective current density target.
- Read the auto-populated total current requirement in Amperes directly below the form.
- Cross-check the result against your project spec sheet; remember this is a preliminary estimator only.
FAQ
Q: How is the coating breakdown factor calculated according to ISO standards?
A: Per ISO 15589-2 and DNV-RP-B401, the final factor is f_cf = a + b × t and the mean factor is f_cm = a + b × t/2, where a is the initial breakdown, b the yearly increase and t the design life in years. Size galvanic anodes on the mean current; check the end of life with the final one.
Q: Can the coating breakdown factor exceed 1.0 in the calculation?
A: No. The model physically clamps f_c at 1.0 once the coating is fully degraded, preventing impossible current overestimations beyond bare-pipe requirements.
Q: What units should I use for current density?
A: Enter standard pipe industry units of milliampères per square meter (mA/m²); the calculator automatically converts to amperes during computation.
Q: Is this output suitable for final equipment specification?
A: This is strictly a preliminary estimator. For galvanic anodes, enter the mean current in the Sacrificial Anode Mass Calculator; for impressed-current systems the rectifier must also cover cable losses and stray currents, confirmed by a detailed corrosion survey.