FAILURES OF BRASS CONDENSER TUBES
Biljana Bobić1, Bore Jegdić1, Branimir Jugović2, Jasmina Stevanović1, Bojan Gligorijević3, Alin Murariu4
1)University of Belgrade, Institute for Chemistry, Technology and Metallurgy, Belgrade, Serbia,
2)Institute of Technical Sciences, SANU, Belgrade, Serbia
3)University of Belgrade, Innovation Centre of the Faculty of Technology and Metallurgy, Belgrade, Serbia
4)ISIM, Timisoara, Romania
Causes of failure of brass condenser tubes (CuZn28Sn1) in a thermal power plant in Serbia are analysed. Results of testing by Fourier transformed infrared spectroscopy (FTIR) have indicated the presence of ammonia and nitrogen compounds on fracture surfaces and on the inner surface of the tubes. These compounds are specific agents that cause stress corrosion cracking (SCC) in brass. Analysis of fracture surfaces using scanning electron microscopy (SEM) has shown the brittle transgranular fracture due to the occurrence of SCC. The resistance of brass condenser tubes to other types of corrosion, such as erosion, general and selective corrosion (dezincification) is also considered. Some procedures are proposed to reduce the risk of SCC in the brass condenser tubes.
Keywords: condenser tubes, brass, stress corrosion cracking, dezincification