Offshore structures comprise fixed platforms, mobile rigs, sub-sea pipelines, mooring buoys, harbours, and jetties; they are of steel, but sometimes of concrete. All categories need cathodic protection to prevent the steel corroding in sea water. Full cathodic protection requires that all points of the steelwork have steel/sea-water potentials more negative than--0.8 V wrt Ag/AgC1. The protective current necessary may be provided by the use of electronegative materials such as magnesium, zinc or aluminium (sacrificial-anode cathodic protection), or alternatively by the use of relatively inert anodes with an external direct-current power source (impressed-current cathodic protection). The advantages and disadvantages of both systems are mentioned and different types of anode materials compared. The use of retrofit anodes is briefly discussed; there is a definite requirement to design speedily attached underwater retrofit anodes. Special bracelet anodes designed for retrofit are an economical way of installing sacrificial-anode material. These bracelets have an added advantage in that they are more integral with the structure than an anode standing off from the members and this concept may be extended to new structures.

  • Corporate Authors:

    Morgan-Grampian Limited

    30 Calderwood Street
    London SE18 6QH,   England 
  • Authors:
    • MacKay, W B
  • Publication Date: 1980-1

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00314998
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Aug 27 1980 12:00AM