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Sacrficial anodes thruster tunnel

Design lifetime of sacrificial anodes

The amount of anode required to protect a metal structure corresponds directly to the surface area of the metal exposed. The better the coating, the less anode material is needed.

The arrangement of the anodes is planned so as to provide an even distribution of current over the whole structure. The shape and mass of the anodes are designed to protect the structure for the required time.

Typical design lifetime of anodes:

For ships: 1-5 years
For harbours: 15-30 years
For offshore subsea structures: 10-50 years

The design life of anodes is normally specified by owner.

Intact coating drastically reduces the mass of anode material required. You may learn more about design for ships system.

Maintenance and repair of anodes for fixed offshore structures are generally very costly and sometimes impractical. It is therefore normal practice to apply at least the same anode design life as for the protection object.

However, in certain circumstances planned retrofitting of sacrificial anodes may be an economically viable alternative to the installation of very large anodes initially. This alternative should then be planned such that necessary provisions for retrofitting are made during the initial design and fabrication.

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