US - Testing is in 83569. 8339 includes possibly detection and control programs.
Australia - Agree that "corrosion detection" should be in 8339. May need an exclusion in 83569.
RB - The difference between 8339 and 83569 seems to be the type of object tested, rather than the method used. With this, corrosion testing would be correct in both classes. However, "dams" are included in both classes (83392, 83569), creating a problem. Looking at the type of object tested, it seems that "dams" should be removed to 83569.