Thermally sprayed aluminium and Zinc coating for Tidal Zone Cathodic Protection of Offshore Platform Pile Legs

摘要

The sprayed zinc and the aluminum-zinc coatings provided effective CP on the tidal zone areas of the marine platform pile legs. The substrate was protected from corrosion even when the organic paint on the surface peeled off. Aluminum coating alone did not provide effective protection. The organic paint used to seal the sprayed metal coating must have high cohesive affinity and penetration. Among the three organic sealer coatings, the chlorinated rubber paint was the best sealer for the metallic coating. The two-year experiment in the open sea showed that the most effective protective method is to spray zinc coating first, then aluminum coating, and then seal the metal coatings with an organic coating. The preparation of the substrate surface is crucial for corrosion prevention by thermally sprayed metallic coating. The blasted surface should have a white metal blast appearance with an anchor-tooth surface profile of 50 to 75 um. The surface preparation must achieve more than Sa 2.5 grade.