Cathodic protection design and installation
Cathodic protection (CP) is added to steel structures to help prevent or slow the rate of corrosion. Within the maritime environment this is a common means of improving the durability of structures.
Cathodic protection systems will either be a sacrificial or active CP system. A sacrificial system will work by placing metals with higher electro-potential than steel next to the structure and then ensuring the two metals are electrically coupled. The sacrificial metal then takes the role of anode in the electro-chemical process.
Constructex has worked with its clients to install cathodic protection systems to a variety of structures, including: sheet pile walls, bearing piles, jetties, vessels and boat hoists.
Anodes will typically be installed below lower water level (although sometimes the seabed will not permit this - as shown in the adjacent picture). The anode will ideally then remain submerged at all states of tide. The anode will help protect the steel within the intertidal zone and the submerged zone. The intertidal zone area will still sufffer from corrosion and the area above the tidal zone will require separate protection by other means (e.g. a coating system - see Constructex marine coating services).
Sacrificial anodes will have a design life and will then need to be replaced. It may be possible to reuse the existing fixing brackets which, if well designed, can reduce the cost of installation.