Study and Evaluation of the Failure of Boiler Tubes under External Erosion

Abstract

Boiler tubes are critical components in power generation systems, operating at 400–600°C and pressures up to 15 MPa. Continuous exposure to erosive agents such as fly ash, soot, and high-velocity flue gases (20–35 m/s) leads to external erosion and premature material failure. This study presents a comprehensive quantitative evaluation of boiler tube failure under external erosion, emphasizing the correlation between metal loss, micro-structural degradation and mechanical integrity. A relationship rarely integrated in previous research, which often focused solely on visual or thickness assessments. Visual inspection, ultrasonic testing, metallographic analysis and hydrostatic testing were performed on degraded super-heater tubes. The results revealed wall thickness reduction from 4.8 mm to 2.9 mm (38% material loss), an average erosion rate of 0.12 mm/year and a hardness decrease from 185 HV to 148 HV. Hydrostatic evaluation showed that eroded sections retained 90% of design pressure capacity, with a projected remaining service life of 3.5 ± 0.3 years. The distinctive approach of this work lies in its integrated diagnostic approach and data-driven life prediction model, which jointly assess the mechanical, metallurgical, and operational aspects of tube degradation. The findings provide actionable insights for predictive maintenance, material upgrading, and operational optimization, directly supporting safer, more efficient, and longer-lasting industrial boiler operation.