Corrosion of Steel and Metal-Coated Steel in Swedish Soils—Effects of Soil Parameters

Abstract

This report presents a systematic long-term field study of corrosion in soil of carbon steel and steel coated with zinc and an aluminium-zinc alloy (55% Al/Zn). Exposure is taking place in seven localities with different types of soil. In the report, the effects on corrosion of the groundwater table, embedment in sandfill, soil pH, type of soil, specimen size, and time of exposure are evaluated. The results are based on up to four years of exposure.

Empirical models for long-term localised corrosion of cast iron pipes buried in soils

“…Ground water was observed at only a few sites and then usually below the pipe (Table 1). However, Swedish studies concluded that for pipes below the water table corrosion was mainly 'uniform', with limited evidence of pitting or localised corrosion [25]. This is consistent with other observations for immersion corrosion, including in marine conditions [17].…”

Electrochemical Monitoring of Steel/Soil Interfaces during Wet/Dry Cycles

“…The average corrosion rate deduced from residual thickness measurements in the other strongly corroded areas was actually found between 300 and 500 μm yr −1 . These values are consistent with average pitting rates measured in Swedish natural sites after three years in a muddy clay soil (up to 450 μm yr −1 ), 7 or after 10 years in silt loam soils (up to 460 μm yr −1 ). 19 Shallow broad pits are also visible in the less degraded parts of the metal surface.…”

“…Accordingly, corrosion of steel in soils has been studied and the influence of numerous parameters such as aeration, moisture, electrical resistivity, pH, composition or microbiological activity already has been addressed e.g. [2][3][4][5][6][7][8][9][10][11][12][13] It is generally agreed that soil moisture is the most important parameter because it governs the crucial process of transport of O 2 from the atmosphere to the steel surface. 11 In soils close to saturation, the corrosion rate remains low because the cathodic reaction rate is controlled by the diffusion of dissolved O 2 in the electrolyte filling the pore network of the soil.…”

A Probabilistic Model for the Failure Frequency of Underground Gas Pipelines

“…Rupture models currently under development use both rates, and these models may be encorporated at a later time (Hopkins et al, 1992). Given these factors, the corrosion rate is assumed constant in time (Camitz et al, 1989).…”