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Copper occurs naturally with elements such as lead, nickel, silver and zinc. It is widely used in industry both as a pure metal and as an alloying material. The copper industry is composed of two segments: producers (mining, smelting and refining industries) and fabricators (wire mills, brass mills, foundries and powder plants). The end products of copper producers, the most important of which are refined cathode copper and wire rod, are sold almost entirely to copper fabricators. A modern and comprehensive document on the subject is the second edition of the classic CORROSION BASICS textbook.
The end products of copper fabricators can be generally described as mill products and foundry products, and they consist of wire and cable, sheet, strip, plate, rod, bar, mechanical wire, tubing, forgings, extrusions, castings and powder metallurgy shapes. These products are sold to a wide variety of industrial users.
The resistance of all grades of copper to atmospheric corrosion is good, hence their wide usage for roofing and for contact with most waters. The metal develops adherent protective coatings, initially of oxide, but subsequently thickening to give a familiar green patina on roofs and the dark brownish color of bronze statuary. Because copper is largely unaffected by potable water, its is widely used for tubes carrying domestic and industrial water. In the following broad classifications, copper and copper alloys have demonstrated superior corrosion performance:
Atmospheric exposure such as roofing and other architectural applications
Plumbing systems with superior corrosion resistance to both potable waters and soils
Marine applications involving supply lines, heat exchangers, and hardware where resistance to seawater and biofouling are mandatory
Industrial and chemical plant process equipment involving exposure to a wide variety of organic and inorganic chemicals
