Corrosion and Corrosion Inhibition of Steel Pipelines in Montmorillonitic Soil Filling Material.

Buried steel pipelines pass through different soils therefore; it could be subjected to dissimilar soil corrosion. A possible way to overcome this problem is using one kind of soil as filling material. The investigated filling materials were collected from Faiyum depression. XRD analyzes revealed that the soil composed mainly from montmorillonite, kaoilinite, illite and potassium chloride. The corrosion behavior of mild steel in the clayey soil was investigated by electrochemical techniques in correlation with moisture level. The results showed that, there are an increase of the corrosion rate with moisture content up to 40% by wt and a further increase in the moisture had no significant effect. Minor additions of CaO up to 0.5% by wt were added to the filling material to reduce its corrosivity. The results showed that the corrosion rate of steel is highly reduced with CaO. The reduction was related to the role of CaO in reducing moisture level and increasing clay alkalinity. [ABSTRACT FROM AUTHOR]