| 5. Cathodic Protection | |
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5.4 Important Measurements in Cathodic Protection [1/3] |
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Important Measurements in Cathodic Protection
The most important measurement for designing a cathodic protection system is soil resistivity. It is an important parameter for determining the current requirement of the system. The soil resistivity qualitatively signifies the corrosivity of the soils as shown below:
Table 5.5: Relationship of Soil Resistivity to Soil Corrosivity
|
Soil Resistivity (ohm-m) |
Soil Corrosivity |
| 0 - 500 | Extremely corrosive |
| 500 - 1,000 | Highly corrosive |
| 1,000 - 2,000 | Above-average corrosive |
| 2,000 - 4,000 | Average corrosive |
| 4,000 - 10,000 | Mildly corrosive |
| above 10,000 | Non-corrosive |
The resistivity of soils is not a property of a soil but an indication of its properties. It depends on
chemical content
moisture content
temperature
Table below shows the difference between the corrosive and non-corrosive soils.
Table 5.6: Corrosive and Non-Corrosive Soils
|
Corrosive |
Non-Corrosive |
| High moisture content | Low moisture content |
| High chemical content | Low chemical content |
| High acidity | Low acidity |
| Presence of Sulfphides | Presence of Sulphates |
| Low electrical conductivity | High electrical conductivity |
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