Environments
`The corrosion resistance of any metallic material depends on the environment to which it is exposed. There are different types of environment that can cause the corrosion such as:
- Atmospheric Corrosion
- Natural Waters
- Seawater
- Corrosion in Soils
- Reinforced Concrete
- Microbes and Biofouling
- Rural: It means that this type of corrosion does not contain chemical pollutants, but it contain organic and inorganic particulates. The main corrodents are moisture, O2, and CO2.
- Urban: this type of corrosion is very similar to Rural but some little addition pollutants such as SO2 and NO2 are in the pollutants too.
- Industrial: These atmospheres have heavy industrial Pollutants such as SO2, chlorides, phosphates, and nitrates.
- Marine: Marine Corrosion is Corrosion resulting from exposure to saltwater or the air at locations near the sea, especially at temperatures above 21oC. Marine atmospheres are usually highly corrosive, and the corrosion ability is dependent on wind direction, wind speed, and distance from the coast.
Atmospheric corrosion can be defined as the corrosion of materials exposed to air and its pollutants; it can be classified into dry, damp, and wet categories. Atmospheric corrosion can be classified as following:
Natural Water: A major use of water in industry is such as 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 can be corrosive to most metals. Pure water, without dissolved gases (e.g., O2, CO2, and SO2) does not cause unnecessary corrosion attack on most metals and alloys at temperatures up to at least the boiling point of water.
Seawater: Seawater systems are used by many industries, such as shipping, offshore oil and gas production, power plants, and coastal industrial plants. Seawater is one of the most corroded and most abundant naturally occurring electrolyte. The corrosively of the seawater is reflected by the fact that most of the common structural metals and alloys are attacked by this liquid or its surrounding environments.
Soil Corrosion
Soil corrosion is a geologic hazard that affects buried metals and concrete that is in direct contact with soil or bedrock. Soil corrosion is a complex phenomenon, with a multitude of variables involved. Pitting corrosion and stress-corrosion cracking (SCC) are a result of soil corrosion, which leads to underground oil and gas transmission pipeline failures.
Concrete
Concrete structures such as bridges, buildings, elevated highways, tunnels, parking garages, offshore oil platforms, piers, and dam walls all contain reinforcing steel (rebar). The principal cause of degradation of steel-reinforced structures is corrosion damage to the rebar embedded in the concrete. The scale of this problem has reached alarming proportions in various parts of the world.
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