Marine Cathodic Protection: Why ICCP Is Preferred for Vessel and Offshore Assets

Corrosion is the leading threat to the integrity of steel ship hulls and offshore platforms. While coatings and sacrificial anodes can provide initial protection, they rely on natural processes to maintain performance and do not last indefinitely. Impressed Current Cathodic Protection (ICCP) has thus emerged as the preferred active form of protection for ship owners and offshore operators, enabling consistent, controllable and long-term protection. The SME technical team has successfully completed over 500 retrofit and maintenance projects annually on board vessel and offshore assets in shipyards worldwide. Wherever a durable and low-maintenance approach to corrosion control is needed, ICCP is recommended.

What ICCP is: Defining Active vs. Passive Cathodic Protection

Understanding why ICCP outperforms sacrificial anodes (the passive counterpart) is the first step to appreciating its technical advantage.

Sacrificial Anodes-Passive, Galvanic Protection. Sacrificial anodes use dissimilar metals such as zinc, aluminum, or magnesium which have a lower potential than steel, and therefore, must corrode preferentially to protect the hull. Simple and cost effective for small craft, these systems deliver a finite amount of current as the anode sacrifices itself. The electrical potential of sacrificial anodes changes dynamically with the seawater resistivity and temperature, which affects current output.

ICCP-Active, Controlled Protection. ICCP employs a direct current power source that impresses an electrical current onto the steel hull, making it the cathode. High-rated inert anodes (like Mixed-Metal Oxide coated Titanium) are used to distribute current into the sea. Unlike sacrificial anodes, ICCP utilizes reference electrodes to monitor the hull's electrical potential and a sophisticated control panel to maintain optimal cathodic protection levels under changing environmental conditions such as ship speed, water temperature, and salinity.

Key Benefits for Ship Owners and Offshore Operators-Why ICCP is Preferred

Compared with passive sacrificial anode systems, ICCP provides significant operational advantages to the vessel or offshore owner:

Longevity of anodes: In ICCP systems, the anodes themselves do not corrode as their current is impressed from a power source. This means that properly designed ICCP anodes will last from 15-20 years compared with typical 3-5 years for sacrificial anodes. For expensive offshore infrastructure requiring less frequent, and significantly more expensive dry-docking cycles, such an improvement can be very significant.

Savings in weight and space: Sacrificial anodes add around 1-2% to the lightship weight of the vessel, and steel attachments required to house the anode are welded to the hull, producing a concentration of stress and also, at best, an obstacle to streamlining. ICCP utilizes small anodes that are flush welded to the hull, thus producing little or no increased drag. For performance oriented vessels, such drag reduction will have direct and significant impacts on the vessel's operational costs: increased speed at the same power, or reduced power at the same speed, which translates directly into fuel savings.

Automatic and adaptive operation: ICCP systems employ reference electrodes that measure the hull's potential in real-time. When changes occur—such as increased speed or in tropical water temperatures-the controller detects them immediately and alters current output accordingly, ensuring optimum protection is maintained automatically throughout. Sacrificial anodes offer no feedback and their output cannot be adjusted to account for any change.

Key Installation, Maintenance, and Service: Factors for Success

Although ICCP requires careful engineering, it is a robust solution which relies on a high level of service to deliver sustained performance.

Sizing and Design: A properly designed ICCP system matches the level of required protection to factors such as wetted surface area, vehicle speed and condition of protective coating. An undersized system will not be able to properly protect the hull, whereas an over-sized system may overprotect the coating, causing it to disbond or damage the steel via the creation of hydrogen. SME's team uses sophisticated engineering programs to correctly dimension the current output of its systems and distribute the anodes in optimum positions.

Installation Expertise: Accurate mounting of anodes, reference electrodes, junction boxes and system wiring is critical in maintaining efficient operation and must take electrical grounding and environmental resilience into account. SME's Nantong workshop, measuring 5,000 m², enables high quality, pre-fabrication and testing of components to be carried out before the installation stage, minimizing vessel on-hire time.

Ongoing Support: Although designed as a "set-and-forget" system, to ensure long-term reliability and efficient operation periodic checks on reference electrodes are recommended. SME’s global network ensures we can provide inspections, repairs, fault finding, and prompt replacement parts readily to any global location from a network spanning 5,000 service points worldwide; importantly, all SME work is covered by our full 12-month guarantee. We have performed hundreds of ICCP retrofits and refits on both vessel and offshore assets, on clients who require world leading standards and class certification with particular emphasis on work within the major shipyards throughout mainland China for an international client base.

Environmental considerations and classification compliance

ICCP is advantageous compared to sacrificial anodes in environmental regulations when considered against other options: Sacrificial anodes consist of metals, which if corrode to a degree which passes threshold values, do contribute to a heavy metal presence in water. ICCP utilizes non-corroding elements for the anodes. Oxygen and hydrogen are the only by-products of an ICCP system.

SME is ISO 9001, ISO 14001 and ISO 45001 certified and systems supplied are ANAB, IAF and UKAS approved.

Conclusion: SME Provides Dependable ICCP Solutions Globally

For owners of vessels, offshore structures and their operations teams, ICCP represents the pinnacle of modern corrosion protection; active, automatically controlled and cost effective. At SME, with the advantage of over one hundred technical professionals, a high-tech 5,000 m² workshop and a truly global service support network, we are best placed to deliver turnkey ICCP solutions, from initial design and prefabrication, through installation and into a comprehensive lifetime service commitment. Having completed over 500 projects annually with spare parts support for over 1,000 vessels, SME’s international reputation has earned it the trust of major ship owners and operators across worldwide shipyards, particularly in mainland China.

Our guiding principle "Aim Beyond Your Concern" guarantees responsive and effective service and we back every project with a full 12-month guarantee. Contact SME today to discuss your specific needs for cathodic protection.