Failure Analysis of B30 Alloy Tube Used for Vessel Auxiliary Condenser in Seawater

Early failure happened in large areas of B30 alloy tube used for vessel auxiliary condenser. The failure reasons were analyzed through corrosion morphology, corrosion products and polarization curves. The results indicate that selective corrosion happened to B30 alloy, and the most serious corrosion in local area of inner surface was de-nickel corrosion because of pitting. The acidic environment in the pitting pits made de-nickel corrosion more serious. Potential of copper is more positive than that of nickel,so copper could deposited on grain boundaries.