Concepts of Underground Corrosion

Abstract

Corrosion in soil is a complex phenomenon, but there are some basic concepts that are useful in understanding the process. Underground corrosion is electrochemical in character, and this fact is used to describe the corrosion process in terms of an ordinary dry cell. The differences between corrosion in disturbed and undisturbed soil are discussed, and data are presented to emphasize these differences. The results reveal that soil composition is less important than soil resistivity, but both are subordinate in importance to oxygen availability. Thus, corrosion is negligible in undisturbed soils where oxygen concentration is low.

Corrosion by Soils

“…Soil conditions aggressive to steel buried under disturbed conditions were not corrosive to steel pilings in undisturbed soil. Corrosion was found to be variable but not serious above the water table [34,35] and negligible below the water table. Correlations between soil properties and corrosion developed for buried steel structures were of no practical value in predicting the corrosion of pilings.…”

Evaluation of Corrosivity of Soil Collected from Central Part of Kathmandu Metropolis (Nepal) to Water Supply Metallic Pipes

“…36 and 37) are considered to be less corrosive, because they have the resistivity more than 20000 Ohm.cm. These results revealed that about 52 % of the soil samples collected from the central parts of Kathmandu metropolis are considered to be mildly and moderately corrosive, while about 44 % of the soil samples are considered to be corrosive to the buried-metallic pipes based on the soil resistivity value according to the ASTM classifications as summarized in Table-1 [29,30]. Oxidation-reduction potential of soil: It was found that the oxidation-reduction potential of all soil samples analyzed in this study was found in the range of +158 to +537 mV vs. saturated hydrogen electrode as shown in Fig.…”

Evaluating the soil corrosion of Bushehr, Iran, based on a new classification system for corrosive soils

“…The redox potential is a measure of the degree of aeration in a soil. Very high corrosion rates have been observed in poorly aerated (reducing) soils where anaerobic bacteria often thrive (Escalante, 1989). Starkey and Wight (1945) observed a relationship between redox potential and soil corrosion as shown in Table VI.…”