Class notation to ensure a higher corrosion prevention standard.
Purpose
The notation is intended to ensure a higher corrosion prevention standard, aimed at extending the useful life of a ship's tanks and holds.
Benefits
The notation implies that the ship may have less need for maintenance. However, this will depend on proper surface preparation and the selection and application of the coating system. Through the COAT-2 notation, the owner can specify a good corrosion prevention system for its newbuilding. During construction, the yard, ship owner and paint manufacturer can utilise the coating system specification to ensure that the intended quality is obtained.
The benefits of the COAT-2 notation are:
Problem areas known to be susceptible to corrosion, such as ballast tanks, are given a high quality protection
Well defined protective coating systems
Market appreciation of a well-protected ship
Features
The notation is aimed at preventing the provide corrosion of important areas on board the vessel. Areas regarded as critical with respect to corrosion are selected, such as water ballast tanks and crude oil cargo tanks. For instance, in double hull crude oil tankers, bacterial corrosion has been experienced. The notation therefore specifies that the inner bottom and area below deck are to be coated. These are important corrosion prevention areas, particularly due to cost-demanding access during a ship's operational phase.
DNV does not perform any inspections or verification of the surface preparation and coating application at the yard. Documentation of deviations from specification is, however, to be provided to DNV as the basis for the notation.
The coating systems relevant for COAT-2 are described in Classification Note 33.1.
Coating systems II and III aim at a useful life of 10 and 15 years, respectively.