Corrosion can occur on external and internal surfaces of pipes, tanks and radiators. In the design phase various issues have to be considered such as pipe material, insulation, medium, humidity and air purging etc.

Internal corrosion can occur if there is oxygen in the pipe or if there is very fast flow in the fittings. To prevent corrosion, system speeds should not be too high, and air must be prevented from getting into the system, e.g. do not use pipes into which air can diffuse. Air vents can be added if required as this will limit the amount of oxygen in the water. 

External corrosion occurs when a steel pipe is fitted in a humid environment or when condensation occurs on the surface of a pipe used to transport a cold medium. Thus, the outer surfaces of cooling system pipes need to be protected from corrosion or to be made from non-corrosive materials such as plastic. Because air can diffuse through plastic, plastic pipes should not be used together with steel pipes.
Corrosion can occur in a tank or radiator when slurry precipitates in the bottom or when air accumulates in the top.