Review the types of water used in service
Discuss water constituents in relation to the corrosivity of water
Describe the impact of water pH on steel and aluminum
Summarize the various scaling indices used to characterize water corrosivity
This Module consists of four Web pages of required reading. The pagination is visible at the bottom of each page with direct links to adjacent pages.
Additional information can be found in sections 8.1 to 8.7 of the reference textbook (Corrosion Engineering: Principles and Practice).
A major use of water in industry is the transfer of heat and the production of steam. There is extensive use of cooling water in almost every manufacturing process, in commercial air conditioning, and even a substantial percentage in domestic air conditioning. Water is used in the passive sense for potable and for fire control purposes. Fossil and nuclear fuel steam plants are encountered in the heating and power generating fields.
According to the American Waterworks Association (AWWA)
industry database, there is approximately 1,483,000 km of municipal water piping
Water can be corrosive to most metals. Pure water, without dissolved gases (e.g., oxygen, carbon dioxide, and sulfur dioxide) does not cause undue corrosion attack on most metals and alloys at temperatures up to at least the boiling point of water. Even at temperatures of about 450oC, almost all of the common structural metals, except magnesium and aluminum, possess adequate corrosion resistance to high-purity water and steam. In summary, the factors influencing the corrosion of materials in water systems are:
Physical configuration of the system;
Chemistry of the water (hardness salts, chlorides, and dissolved gases being the most important);
Presence of solids in the water;
Temperature of the water;
Presence of bacteria.
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See also CCE 513: Corrosion Engineering