sacrificial Anodes on ships

How to Assess if the Anodes are Working Properly or Not?

During the inspection of heat exchangers or sea chest, if the condition of anode is same as it was installed then it indicates that the sacrificial anodes are ineffective.

The main reason for this is that the electrical continuity between the parent materials is not made. Because of this the parent metal starts getting corroded instead of the anodes. It is therefore important to check the electrical continuity during installation.

 

Frequency for Changing of Anodes

The frequency for changing of anodes depends on the application where the anodes have been used. If sacrificial anodes are used for heat exchangers and it is found during inspection that the anode left is only 10% then also it has to be changed.

In case the anodes are attached to the ship’s hull, then they are to be checked during dry dock which takes place after 2 to 3 years. If the anodes are found completely corroded then anodes of bigger size should be fitted, for fully corroded means that the material used was of poor quality or a large amount of material is required to protect the hull. Generally, sacrificial anodes are changed at every dry dock.