The material of seawater pipeline (circulating water pipeline, open water pipeline and oil cooler inlet and outlet pipeline) usually is Q235A or 10CrMoAl. The inside wall of pipe is exposed in the seawater, corroded by seawater. Meanwhile, for the equipment of high potential material in the system including condenser, water heat exchanger, oil cooler, secondary filter screen, ball collector-strainer and valve, the materials are nickel-chromium cast iron, 316L and 317LN stainless steel. The seawater pipe with quite low potential is connected with the equipment with high potential. The macro primary battery and pipeline in the system must suffer the serious galvanic corrosion. Usually, the pipe wall becomes thinner due to corrosion, even perforating and leaking.
typical corrosive damage of equipment before cathodic protection