ISSN:
1745-6584
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Geosciences
Notes:
Saline waters usually are more corrosive to metals than ordinary fresh waters. To predict whether saline ground water will be corrosive to steel, it is necessary to understand the effect of such factors as: (1) the salt content, (2) the dissolved gases, (3) the pH, (4) the temperature, and (5) the tendency to form mineral scale. If the water contains several thousand parts per million of sodium and other chlorides, it is likely to attack many metals, particularly steel and low-alloy steels. Stainless steels, copper alloys, aluminum alloys, and some nickel-base alloys also may be attacked, depending on conditions.Of the dissolved gases, oxygen is most important. The higher the oxygen content the more corrosive the saline water, particularly to steel. On the other hand, high-oxygen content tends to promote passivation of aluminum and stainless steels. If the saline water is acid (with a pH well below 5), direct attack of the metal accompanied by hydrogen evolution may be expected. Under these conditions, the rate of attack often is very rapid and oxygen is not needed for the corrosion reaction.As the temperature is increased, the corrosion rate usually is accelerated. However, if one considers a saline water at atmospheric pressure, an increase in temperature will reduce the oxygen solubility. It has been observed that high-temperature brines from anaerobic wells usually do not corrode steel. Also metastable waters, containing calcium and magnesium salts, may form mineral scale upon being heated. This scale, if it forms a tight coating, slows down or stops corrosion. Galvanic couples in equipment such as valves, pumps, screens, and well fittings in general, often are a serious corrosion problem in practice.It is recommended that pilot corrosion studies be made of candidate designs in a specific ground water at the pressure and temperature which exists in service. Many saline waters, particularly those containing oxygen, are found corrosive to common metals. Some of the factors which influence corrosion are described.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1745-6584.1963.tb01929.x
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