Here are the Wilson Walton International Principles of Cathodic Protection
The Problem: Natural Electrochemical Corrosion
- When two dissimilar metals are in contact within an electrolyte (e.g., seawater), a corrosion cell forms: one metal acts as the anode and corrodes, while the other becomes the cathode and remains intact.
- Even within a single metal structure, microscopic variation (composition, stress, coating, oxygen exposure) create localized anodic and cathodic zones, accelerating corrosion..
The Solution: Controlling the Corrosion Process
- Cathodic protection involves introducing a more electro-negative metal as a sacrificial anode. That anode corrodes instead of the protected structure, effectively turning the structure into a cathode
- Common materials used include zinc and aluminum:
- Zinc anodes: ≥99.995% purity, per US Mil Spec A-18001K, yielding ~780 Ah/kg.
- Aluminum anodes: mercury-free alloy, yielding ~2700 Ah/kg — lighter and longer-lasting
Two Main Cathodic Protection Systems
Galvanic (Sacrificial) Cathodic Protection
- A passive system exploiting the natural electrochemical potential difference between the sacrificial metal and the structure.
- Anodes (zinc, aluminum, or magnesium) are attached directly; current flows naturally to protect the structure.
Impressed Current Cathodic Protection (ICCP)
- Active system using an external DC power source to drive protective current via inert anodes (e.g., mixed-metal oxide on titanium).
- Wilson Walton’s Aquamatic® ICCP systems:
- Hull-mounted anodes and reference electrodes feed into a Control Power Unit (CPU) that monitors potential and adjusts current to maintain the set polarization level.
- Systems are autonomous, maintenance-light, and optimize protection as seawater resistivity changes.
Typical Applications & System Components
- Galvanic: small vessels, outboard motors, localized protection areas (< pipeline segments)..
- ICCP: large structures such as ship hulls, offshore platforms, long pipelines, or high-resistivity environments (where sacrificial anodes aren’t enough).
- Wilson Walton manufactures its own sacrificial anodes and full ICCP systems, including hull-mounted anodes, reference electrodes, junction boxes, cables, and CPUs
Summary
- Identify: Understand that corrosion stems from electrochemical cells between anodic and cathodic areas.
- Protect: Use either sacrificial anodes or powered ICCP to shift anodic reactions away from the structure.
- Maintain: Continuously monitor electrical potential and adjust current—especially in ICCP systems—for optimal, long-term protection.
SPECIFICATIONS for Wilson Walton’s Zinc vs. Aluminum sacrificial anodes, plus more info on their Aquamatic ICCP systems:
Zinc (Zincoline) Anodes
- Composition & Compliance: High-purity zinc cast to U.S. Mil-Spec A-18001K standards; also available in Special High Grade alloy
- Performance: Approximately 780 Ah/kg capacity, with a solution potential of –1050 mV vs. Ag/AgCl in seawater
- Applications: Ideal for hulls, ballast tanks, sea chests, piers, buoys, and areas where aluminum is restricted (e.g., tank tops)
- Cost: Pricing is provided via quote; stock is available for immediate bulk supply
Aluminum (Aloline) Anodes
Change to “Wilson Walton doesn’t prominently list aluminum specs online, but typically aluminum has around 2,700 Ah/kg, making it lighter and longer-lasting than zinc. It’s often used where zinc is forbidden (upper tanks). For detailed alloys, weights, or sizes please submit an RFQ for a prompt answer on how Wilson Walton can serve you.
Aquamatic ICCP (Impressed Current Cathodic Protection) Systems
Components & Specs
- Change to “Controller Power Unit (e.g., Aquamatic IV):
- Switch-mode, single-phase AC input (85–264 VAC, 47–63 Hz).
- Outputs up to 2 A per channel × 4 anodes (0–12 V range).
- Sensitive regulation (±0.01 A), diagnostics, anode life estimation, and FLOW/NO FLOW detection
- Networked, Monitoring & Recording:
- Aquamatic 4 system integrates sensors, MODBUS connectivity, USB data-logging, and remote reporting.
- Anodes:
- Platinized titanium ICCP “C-Max” or large 225 A units.
- Larger anodes reduce hull penetrations and cut installation weight/cost by ~12% vs smaller ones .
Comparison Summary
| System/Anode | Performance | Weight Efficiency |
|---|---|---|
| Zinc Anodes (780 Ah/kg | Proven, reliable, mil spec | Medium |
| Aluminum Anodes (≈2,700 Ah/kg) | Higher capacity, lighter | Best |
| Aquamatic ICCP (Control Unit) | Precise current up to 2 A/channel ×4 | Compact |
| Aquamatic 4 Complete System | Full hull protection upgrade | Variable |
Next Steps
If you’re considering retrofitting or specifying new protection systems, I recommend:
- Requesting official quotes from Wilson Walton for zinc/aluminum anodes tailored to your vessel’s geometry and required amp-hours.
- Clarifying which Aquamatic versions are current with new unit pricing and service agreements.”
- Evaluating used vs. new systems, verifying warranty status, availability of spare parts, and compatibility with your hull configuration.