5. Cathodic Protection

5.4 Important Measurements in Cathodic Protection [1/3]

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

Table below shows the difference between the corrosive and non-corrosive soils.

Table 5.6: Corrosive and Non-Corrosive Soils



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