How Sacrificial Anodes Protect Ships and Tanks from Rust
Sacrificial Anodes
Sacrificial anodes made of zinc or aluminum are designed to stop rust on underwater ship hulls and in tanks. The number and size of anodes needed depend on the quality of the coating and the area that needs protection.
Sacrificial Anodes for Hulls
Anodes can be customized to fit different designs and needs. See our full range of sacrificial anodes. Below are common anode models used on the submerged parts of a ship’s hull.
Common Sacrificial Anode Models for Ship Hulls
The size and type of anodes depend on several factors: the condition of the coating, the type of construction (hull, rudder, azimuth, sea chest, thruster tunnel, etc.), and the time the vessel will be afloat before the next maintenance.
Choosing Between Aluminum or Zinc Anodes
The durability of anodes depends on their grade and composition, whether the ship has an ICCP (Impressed Current Cathodic Protection) system, and how that system is set up.
Ships without ICCP systems need more sacrificial anodes. If ICCP systems are installed, fewer anodes are required.
Sacrificial anodes made of zinc or aluminum are designed to stop rust on underwater ship hulls and in tanks. The number and size of anodes needed depend on the quality of the coating and the area that needs protection.
Ballast and Water Tanks
When coatings in ballast tanks are damaged or break down, sacrificial anodes are the only way to prevent rust.
Different Tank Anode Designs and Fixing Methods
There are various designs and ways to fix anodes in ballast tanks. Aluminum anodes are generally better than zinc because they offer technical and economic advantages. However, in some tanks, aluminum anodes may spark if they fall off.
Anodes in Ballast Tanks with Residual Water
If residual ballast water is expected to stay at the bottom of the tank, place anodes low, like pitguard anodes on the bottom longitudinals. This ensures higher anode consumption as needed.
Cargo Tanks
In oil and chemical cargo tanks, a saline water layer at the bottom can cause local corrosion, especially if there are noble metals like heating coils and pump units. These metals make the structural steel anodic, leading to quick rusting at bare steel spots.
High-Temperature Conditions
Standard anodes may fail at high temperatures. For tanks carrying liquid cargo at high temperatures, use special HT-Anodes, designed to work consistently up to 90 °C.