Failure analysis of a superheater pipe based on microstructure/mechanical properties study

Abstract

The fundamental role of superheater pipes in turbines is to produce superheated steam and direct it to the turbine. These parts are subjected to damage due to the creep, corrosion and oxidation resulting from combustion exhaust. In this research, the affecting factors of failure in a plantain superheater pipe was investigated. Wet chemistry and SEM/EDS analysis were used to investigate the combustion exhaust deposits and a scanning electron microscope (SEM) was used to study the fracture surfaces in order to determine the mechanisms of the fracture. The results showed that exposure of the superheater pipes at temperatures higher than the standard limits caused strength reduction and occurrence of plastic deformation. Furthermore, the combustion exhaust deposits, caused reduction in heat transfer, in addition to severe corrosion as well as cavity formation due to the presence of hydrogen were the main reasons of the pipes failure.