SPECIAL CORROSION DAMAGE OF HEAT-SUPPLY PIPELINES

The causes of corrosion inside heat supply pipelines were considered. Electrochemical investigations suggest that the presence of scale on t he inner pipe surfaces leads to the appearance of corrosion pits owing to the formation of differential aeration cells in scale defects and pores. The thermal impact exerted during welding support on the pipes changes the structure and protection parameters of oxide layers on the inner surfaces and leads to nonuniformity of the oxide film thickness , which promotes corrosion damage. Polarization measurements of deaera ted and aerated pipeline water show that even a brief increase of the oxygen concentration may cause corrosion pits.