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
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
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).
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.