Heat exchangers are crucial within process industries such as refineries, petrochemical, and chemical plants. They are necessary to decrease or increase the temperature of the process stream. The most common type of industrial heat exchanger is the shell-and-tube type.
The process fluids in the heat exchangers can be highly corrosive and proper material selection is critical for reducing failures, maintenance, and repair costs. A corroding heat exchanger can also cause contamination, which can lead to expensive purification of the products.

A petrochemical plant was using super-austenitic alloy UNS S31254 seamless tubes for a heat exchanger cooling a stream with heavy hydrocarbons. Condensation of hydrochloric acid caused rapid corrosion of the tubes, which gave a lifetime in the range of 6-12 months for the tube bundle. Austenitic UNS N08028 has a better resistance against hydrochloric acid when compared to UNS S31254 and was therefore suggested as a better material solution for the tube bundle. After two years of service, the N08028 tubes showed no signs of corrosion and the process stream after the heat exchanger showed almost no detectable levels of metal ion contamination.

This paper will compare the corrosion properties of UNS S31254 and UNS N08028 in hydrochloric acid and the long-term cost savings achieved by changing tube material in the heat exchanger.