Cathodic protection is what keeps hulls, pipelines and offshore units from corroding. Here is how sacrificial anodes work and where the DNV RP-B401 standard fits in.
What cathodic protection does
Steel in seawater corrodes. Cathodic protection prevents this by making the structure the cathode of an electrochemical cell. With sacrificial anodes, a more reactive metal, typically aluminium, zinc or, for fresh water, magnesium, corrodes preferentially and is consumed instead of the protected steel.
Where the DNV RP-B401 standard fits
For offshore structures, the recommended practice DNV RP-B401 sets out how to calculate cathodic protection, covering current demand, anode mass and distribution, over a design life that can span decades. Designing to this standard is what allows anodes to be sized correctly for demanding applications such as deep-water pipelines.
MGPS and custom anodes
Beyond hull protection, marine growth prevention systems (MGPS) use copper and aluminium anodes to keep seawater pipework clear of biofouling. Custom Ferro, aluminium and copper anodes are produced to suit specific vessels and structures.