Corrosion Damage of Heat Recovery Steam Generator Tubes in the Desalination Plants

Abstract The thermal desalination process uses high temperatures to remove salt from seawater. In these harsh environments, corrosion of materials is more likely at elevated temperatures. Multi-Stage Flash (MSF) system is one of the most common thermal desalination processes where a boiler generates steam to heat seawater, enabling the flash evaporation process under reduced pressure to produce desalinated water. Excessive corrosion was observed on the internal sides of carbon steel tubes of the heat recovery steam generator (HRSG)-economizer section of the boiler. This paper presents the failure case studies of a few economizer tubes, where the presence of copper in the feed water contributed considerably to the escalation of the corrosion process. Pitting due to flow-accelerated corrosion (FAC) was also identified. Thick-lipped cracking due to hydrogen-induced cracking was confirmed. Possible causes of FAC, Hydrogen-induced cracking, and the presence of copper in boiler feed water have been investigated and discussed. Based on this investigative work, few remedial measures have been suggested.