Dezincification assisted cracking of yellow brass tubes in a heat exchanger.

• Failure analysis of a tube and shell heat exchanger was studied. • The yellow brass tubes leaked after five years of service. • The brass tubes suffered severe plug and line dezincification. • Failure of the tubes was dezincification assisted corrosion cracking. Failure analysis was carried out on yellow brass tubes that leaked after five years of service in a heat exchanger. The leaked tubes had numerous longitudinal cracks. The service fluid inside the brass tubes was cooling water, used to exchange the temperature with hot steam at the shell side. Microscopic examinations and energy dispersive spectroscopic analyses were carried out on the brass tube inside and outside surfaces to understand the root cause of the failure. A thin layer of deposits was also observed on the internal and external surfaces of the tubes. Microscopic examinations of the tubes at the fracture edges and cracked areas revealed that the cracks initiated and propagated from the regions that suffered dealloying. Both the plug and line types of dezincification were operative on tube surfaces. The failure investigation suggested that the brass tubes suffered severe dezincification, and the failure of the tubes was dezincification assisted corrosion cracking. [ABSTRACT FROM AUTHOR]