In case of GEA Bloksma coated coolers, the sea-chest is protected against galvanic corrosion by a coating covering all noble surfaces. A long lasting and (intrinsic) reliable insulating effect is ensured, because local damage to the coating results in a small galvanic drain only. Damage to larger surfaces can be taken care of by installing some sacrificial to anodes. The solution is not sensitive for corrosion caused by stray currents. ICCP (Impressed Current Cathodic Protecting) and ICAF (Impressed Current Anti Fouling) systems have no influence on the box cooler.
The unique combination of support baffles and anti-vibration-strips bonded by the coating has been proven to be a solid solution for this problem.
In case the coolers are uncoated, protection of the sea-chest is also a must. Here it is obtained by insulating the numerous joints between the ship and the bundle and it should be checked each time after (re-) assembling. Any fault results in complete failure of the protection mechanism. Sacrificial anodes can give only partial protection or are consumed fast. Stray currents may cause pitting attack of the bundle.
Corrosion occurs also when vibrations induced by uncontrolled flows of the outboard water or by mechanical sources can cause the tubes to rattle in their supports. The protective oxide layer of the tube will be scuffed away locally and as a result pitting corrosion will cause leakage.