FAULT TREE ANALYSIS OF EXTERNAL FACTORS OF SOIL CORROSION FOR BURIED PIPELINE

The soil corrosion is a main form which results in corrosion failure of buried pipelines.Because of the complexity and variety of soil surroundings,the mechanism of electrochemical corrosion and process is complex correspondingly.This paper introduces the mechanism of electrochemical corrosion briefly.Oxygen is deoxidized and OH- ions are created in cathodic area;iron is oxidized and the products of Fe2+ ions are hydrated with water from soil in anodic area.The corrosion factors and structural importance are analyzed by fault tree analysis(FTA),and then the soil corrosion factors and status of anti-corrosive coatings and structural importance are obtained for the reasons of corrosion on buried pipelines.Some measures and proposals are presented for soil anti-corrosive methods.