The history in Japan of adopting corrosion control technologies for cooling water systems is not so long as in European and American countries. In Japan the use of phosphate corrosion inhibitors for carbon steel was the first commercial corrosion protection for cooling water systems. This was followed by the use of zinc, chromate, organic phosphate and the like corrosion inhibitors, which contributed greatly to the development of corrosion control technologies. During 1980's technologies for stabilizing corrosion inhibitors by the use of polymer dispersants were developed, which permitted operating circulating cooling water at higher cycles of concentration. This was quite a technical innovation. More recently, environmental hazards associated with phosphates and heavy materials (chromate, etc.) have led to the development of “nonphosphate and non-metal” programs in which waters soluble polymers play key rules in controlling corrosion. This new direction of corrosion control the technologies has got to be fully established. On the other hand, “non-chemical treatment programs” which do not use any chemical are under consideration. In this paper, special mention is also made of treatment programs for closed recirculating cooling water systems and copper corrosion inhibitors.
