Factors Affecting Stray Currents Corrosion of Buried Pipeline

Abstract

Pipelines are becoming more and more familiar in modern society. Although they are effective seemingly, most of these pipelines are influenced by various corrosions. Stray current corrosion is the most severe form of corrosion because the metallic structure is forced to become an anode and the amount of current can be translated directly into metal loss. One ampere of DC current discharge from a pipeline/well casing for one year may consume 10kg of steel. Stray current is a key role in producing pipeline corrosion. However, it is very complicated to control stray current corrosion because many factors can affect the current flowing between the source and pipelines. Pipeline design and maintenance require factors influencing stray current corrosion. In this paper, soil resistivity, coating worn rate, buried depth and horizon distance have been studied. The specific factor influencing stray currents corrosion are studied by the method of keeping other elements fixed. The results show stray current can be influenced by soil resistivity, coating worn rate and buried depth in different degree. It is favorable to control stray current corrosion by increase soil resistivity, buried depth and horizon distance or decrease coating worn rate. There are boundary values in controlling stray current corrosion by increasing soil resistivity, buried depth and horizon distance. In this laboratory study, the boundary horizon distance is 200mm.