In-situ observation of thermally sprayed metal coatings for protection of the pile legs of the Center No. 2 platform in the Shengli oil field in Chengdao showed good results for zinc and aluminum-zinc. The substrate was protected from corrosion even when the organic paint on the surface had peeled off. Aluminum coating alone did not provide good protection. A two-year experiment in the open sea showed that the most effective protective method is to spray a zinc coating first, then an aluminum coating, and finally seal the metal coatings with organic coating.