The scope of this recommended practice (RP) concerns the corrosion protection of the hull of floating production and storage units with a service life of 15 years or longer. The corrosion protection measures covered by the RP are based on a combination with cathodic protection on a coated steel surface.

The RP covers protection of the steel hull structures against seawater and the marine atmosphere. Ballast tanks and other tanks exposed to seawater are known to be most susceptible to corrosion and are thus of prime concern and are also covered in this RP. External areas such as decks and superstructure will also be susceptible to corrosion and other areas subjected to corrosion are also considered.

The aspects of inspection, maintenance and repair are outside the scope of the present RP. However, in the case that corrosion protection is applied in a manner which does not comply with the requirements in the present RP (e.g. corrosion protection systems with a service life shorter than 15 years) this will lead to increased total life cycle costs of inspection, maintenance and repair (IMR) tasks as compared to total life costs based on the present RP. Useful practices can be found in IACS Recommendation 87, Guidelines for coating maintenance & repairs for ballast tanks and combined cargo/ballast tanks on oil tankers.

Detailed design of anode fastening devices for structural integrity is not included in the scope of this RP. Considerations related to safety and environmental hazards associated with galvanic anode manufacture and installation are also beyond its scope.

The requirements to manufacture of galvanic anodes are not addressed in this RP. For this item, reference is made to the more detailed recommendations in DNVGL-RP-B401.

The present document does not include any consideration of possible effect of CP on the fatigue life of the hull.