Erosion–corrosion of heat exchanger tubes

The shell and tube heat exchanger failed before 5 years of operation. The failure was caused by pits on the tube outside surface developing until its perforation. Inside the Cu-DHP tubes in soft temper a cooling agent circulated to cool down industrial water at the shell side from 16 to 4 °C. The cooled water was hard, rich in chloride ions with relatively low sulphate ions concentration and pH ranging from 4 to 7. The leaking tubes were subject to standard metallographic examination, hardness measurement, scanning electron microscopy and X-ray energy dispersion analysis. It was found that the tube damage was caused by erosion–corrosion induced by two factors: disturbed flow of water containing suspended solid particles and chemical composition of water rich in chlorides that resulted in loss of stability of protective cuprous oxide layer.