In seawater service, heat exchanger tubes must withstand corrosion when exposed to high chloride concentrations. Which degradation mechanism is the primary concern?

• A. Corrosion
• B. Erosion
• C. Fouling
• D. Cracking

Answer: (A)

Chloride ions in seawater drive electrochemical attack on the tube metal, making corrosion the dominant degradation concern. Chlorides destabilize protective oxide films and promote localized dissolution, leading to pitting and crevice corrosion that can thin tube walls rapidly even if the overall metal loss seems small. Erosion is a mechanical wear process from fluid flow and is not the primary chemical risk in this environment. Fouling affects heat transfer more than the material integrity, and cracking, while possible, is typically a consequence of corrosive attack under stress rather than a separate primary mechanism. So, the main threat in high-chloride seawater is corrosion driven by electrochemical reactions at the metal-water interface.