| Abstract |
The influence of acidification on the external corrosion of pipes buried in the soil, was studied in a damage frequency analysis, but no connection was found. The corrosion in soil appears to be mainly dependent on other factors than acidification, such as the type of soil. With respect to the position of the pipe in the soil three cases can be distinguished: (i) Pipes in aerobic soil high above the groundwater level suffer from corrosion due to rich oxygen supply. The corrosion is, however, gradually stifled by precipitation of iron oxides. (ii) Pipes in anaerobic soil below the groundwater level may corrode due to the absence of protective corrosion products. However, depending on the H(sub 2)S/Fe(sup 2+)-ratio a protective layer of FeS may precipitate. (iii) On pipes just above the groundwater level corrosion by the action of aeration cells may occur due to good oxygen supply combined with a fairly low resistivity. Laboratory experiments simulating aeration cell corrosion were carried out with two parallel cells, of which one was sprayed with acidified and the other with non-acidified water. In another investigation the geographical distribution of corrosion induced water damages was compared with the distribution of acidification effects, and a significant correlation was observed. Due to changes in the supply water quality, primarily the pH value, the alkalinity and the sulphate content, the acidification of the groundwater may lead to increased internal corrosion of water pipe installations in buildings. (30 refs., 8 figs.). |
