Coating New Ships: A Corrosion Basic That's Anything But

During the new construction of a seagoing vessel, surface prep and coating application compose a complex orchestration that requires the coordination of every department in a shipyard.

This is also one of the most expensive parts of building a new vessel. It is common to find that the cost of painting an oceangoing vessel is equal to the cost of the steel used to build it. Most owners are willing to take the extra step during painting and obtain the best possible materials and application job. This is because they are aware that corrosion prevention is the most expensive maintenance service required for their ship and the item that can cause extensive downtime for the vessel. If it is funded and managed properly, the coating department can be a highly profitable portion of the yard; otherwise, it can be the largest money loser. This is true for both new build and maintenance.

The work may require following a commercial customer's specification, a military specification, an international regulation, or, most commonly, a combination of standards, regulations, and specifications. The painting of the ballast tanks on an oceangoing commercial vessel must follow the procedures in the International Maritime Organization’s (IMO's) “Performance Standard for Protective Coatings (PSPC).” That rule covers every aspect of the project, from material selection and surface preparation to final inspection and documentation. If the PSPC must be followed, the major decisions for coating work are made by a tripartite group that includes the ship owner, the shipbuilder, and the coating supplier selected by the ship owner.

Just about every type of coating work is performed in a new build yard. Pipe hangers and other small parts are frequently powder coated. Metal parts subject to erosion are coated with molten metal in a metallizing operation. Liquid coatings are applied by both airless and conventional sprays, as well as by brush and roller. Airless spray painting includes the use of both plural-component and conventional single-piston spray equipment.

Surface preparation also includes just about every available type of equipment. Chemical cleaning of some small parts, abrasive blasting in the world's largest automatic blast machines, down to the smallest of glove boxes, as well as standard nozzle blasting, can all be found in a new build yard. Hand and power tools, such as the ubiquitous needle gun, are used every day for cleaning welds and hard-to-reach areas. Ultrahigh-pressure cleaning and even laser removal of coatings can be found in the world's shipyards.

For more information on corrosion and coating with respect to ships, see AMPP's  Maritime News .  

Source:  Previously appeared on materialsperformance.com; an article excerpted from The Marine Coating User’s Handbook, by L.D. Vincent.

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