Analysis of Boiler Tube Failures and Root Causes Using Macroscopic Characterization Techniques

This research investigates the boiler tube failure that was exposed to high-temperature service in the Arjo Didessa sugar factory, Ethiopia. The study aims to analyze the root cause and failure mechanisms of the water tube boiler exposed to high-temperature service for over eight years. Using a field-emission scanning electron microscope fitted with an energy-dispersive X-ray spectroscope and X-ray diffraction, the surface morphology and chemical composition of service-exposed boiler tube surface layers have been characterized. In addition, the research included the investigation of microstructural and micro hardness testing for both high-temperature service-exposed and virgin (new) tube samples. The composition analysis indicated the presence of calcium, magnesium, silicon, sodium, chlorine, and manganese, and deposit layers such as calcite and hematite (Fe₂O₃) were identified. This result revealed that the surface corrosion emerged from the interaction between the boiler tube surface wall materials and the boiler working environment. The metallurgical analysis result also confirmed the microstructural degradation in a boiler tube sample that was due to high-temperature service exposure for a long period. These microstructure changes brought on by exposure to high temperatures with surface oxidation during service deteriorate the mechanical strength of the material.