Light colored ballast tank coatings are the result of the 1990s requirements from the International Association of Classification Societies, IACS and later the International Maritime Organization, IMO, of the United Nations To have more efficient inspection of the condition of the ballast tanks in connection with the increased number of surveys which became necessary due to more demanding rules and regulations.
Light colored ballast tank coatings replaced the black or dark brown coal tar epoxy coatings which were generally accepted as being excellent coatings for the corrosion protection of ballast tanks. This perception of the performance of coal tar epoxy coatings caused many interest groups, especially among ship owners, to raise the question: "Will light colored coatings perform to the same level as coal tar epoxy"?
Inspection of the ballast tanks of ships in service has convinced the authors that the service behavior of light colored ballast tank coatings is at least as good as that of coal tar epoxy.
The inspection results for ballast tank coatings are discussed in this paper. Typical failure causes are shown by examples. Dry film thickness distribution patterns and their characteristics are demonstrated.
The inspection results are used in a discussion of IMO's new Performance Standard, Protective Coatings1 (PSPC).
The use of light colored ballast tank coatings increased dramatically at the beginning of the 1990s. Light colored coatings had been used before, e.g. in countries like Germany due to a coal tar ban, but to a much more limited extent. However, major environmental catastrophes such as the grounding of the oil tanker Exxon Valdez in Alaska in 1989 and the abnormally high number of lost of bulk carriers highlighted the fact that corrosion determines the life time of ships. This led to the requirement for double hull tankers and for much more frequent and stringent surveys of the ballast tanks of all ships. Suddenly a requirement to the performance of ballast tank coatings was imposed: they must be in a GOOD or FAIR condition. Otherwise, if in a POOR condition, the coating must be repaired or the vessel must be surveyed annually2.
The traditional ballast tank coating before the 1990s was the dark coal tar epoxy coating. Some ballast tanks were even left uncoated and others coated with a variety of other - typically one-component - products. A survey in such dark tanks was far from effective, so the more intensive survey regime called for light colored tanks, preferably coated by epoxy and preferably a multi-coat system.
The marine coating industry adapted to the new requirements by introducing new light colored ballast tank coatings. Owner interests, in particular, those who were very satisfied with the performance of coal tar epoxy coatings, were not confident with the new coatings. However, new generations of light colored coatings were developed and evaluated in a vast number of tests in the paint maker's own laboratory and exposed to external laboratory tests, such as the MARINTEK/DNV test regime, before being marketed..
