Common mistakes in the installation and maintenance of sacrificial anodes
Purchasing the correct sacrificial anodes is only half the battle. Many cathodic protection failures attributed to “poor quality material” are actually the result of installation or maintenance errors that prevent the anode from fulfilling its function.
Here, we review the most common mistakes we see in the field and how to avoid them so that your investment in sacrificial anodes truly protects your structure.
sacrificial anodes
The anode protects the structure because there is electrical continuity between the two metals. If the weld, rivet, or cable connection has rust, paint, or a loose connection, the current does not flow correctly and the anode ceases to protect, even if it is physically intact.
How to avoid it: Check electrical continuity with a multimeter after installation, and don’t just rely on visual inspection.
2. Paint or coating on the anode
This is a common mistake in general painting processes of the structure: if the anode (or its connection point) is covered with paint, it acts as an insulator and completely blocks its electrochemical function .
How to avoid it: Mask the anodes before any painting process and check that the contact core is completely free of coating.
3. Incorrect location in the structure
Installing anodes without technical criteria —for example, far away from critical areas such as propellers, pipes or welds— creates areas without effective protection , even if the total amount of material installed is adequate.
How to avoid it: follow the distribution plan designed according to the area and geometry of the structure, prioritizing points with the highest risk of corrosion.
4. Incorrect sizing (too few or too small)
Installing anodes that are smaller or fewer than required — often to “save” on the initial purchase — causes them to be consumed prematurely and leaves the structure unprotected in the medium term.
How to avoid it: calculate the sizing according to the area to be protected, the operating environment and the desired useful life, instead of installing standard quantities without prior analysis.
5. Lack of periodic inspection
One of the most costly mistakes: installing the anodes and not checking them again until signs of corrosion appear on the main structure. By that point, the protection has long since failed.
How to avoid it: establish a visual inspection schedule (ideally at each scheduled maintenance of the structure), checking consumption level, electrical continuity and physical condition of the anode.
6. Mixing anode materials that are incompatible with the environment
Using magnesium in seawater, or zinc in low-conductivity freshwater, drastically reduces the system’s efficiency, because each material is designed for a specific electrochemical environment.
How to avoid it: Select the material (Zinc, Aluminum or Magnesium) according to the actual operating environment, not solely based on availability or cost.
7. Not replacing on time
Waiting until the anode is almost completely consumed (or has already detached) before replacing it leaves the structure without effective protection during that final period.
How to avoid it: replace the anode when it reaches approximately 85-90% consumption, not 100%.
A system as good as its installation
Sacrificial anodes are one of the most reliable and cost-effective technologies for protecting metal structures, but their effectiveness depends directly on proper installation and consistent maintenance . Avoiding common mistakes is what makes the difference between genuine cathodic protection and a false sense of security.
At CONALSOL we not only supply high-performance sacrificial anodes: we support our clients in the correct selection, installation and monitoring, so that the investment fulfills its purpose throughout its life cycle.
Would you like us to check the condition of your current anodes or the design of your next installation? Contact us and we’ll advise you.
