Common materials for heat exchanger tube bundles: 304, 316L, 2205, titanium.

Selection basis: - Cooling water side: 304/316L for circulating water; seawater requires 2205 or titanium (titanium is the most reliable but costly). - Process side: select according to the corrosiveness of the medium; note that one cannot simply choose based on one side alone. - Flow velocity: seawater-side flow velocity is recommended to be ≥1 m/s to reduce deposition, but excessively high velocity will increase erosion-corrosion.

Corrosion protection measures: control water treatment chemicals, clean regularly, avoid crevices and deposits; pay attention to galvanic corrosion at the connection between the tubesheet and tube bundle.

Failure case: 316L tube bundles perforated within 1-2 years under seawater cooling; after switching to 2205, service life was significantly improved.