72-01: Fundamentals of Corrosion in Cooling Water Systems

In a recirculated cooling water system, corrosion of the various metal components of the system is usually a problem. This really isn't too surprising since cooling water systems contain many opportunities for corrosion to occur. 
The water is usually somewhere between "warm" and "hot"; is fully aerated; is relatively high in conductivity; is a fairly good biological nutrient medium; is sometimes loaded with suspended solids; etc. 
This list of potentially corrosive conditions is a rather heterogeneous one; what is it about corrosion that allows all these factors - many apparently unrelated - to be possible causes? To understand this, we must look into the basic mechanism of corrosion of metals and see how all these factors can in­fluence the basic reaction.