Abrasion Failure on ASTM A213 T12 Bottom Slope Tube of Supercritical Boiler

The bottom slope in a supercritical boiler system interface with the waterwall and plays a crucial role in converting liquid phase to superheated steam. Its design must factor in material strength, fluid flow rate, temperature, and pressure. The purpose of this failure analysis is to discern the primary cause of tube failure and avert future occurrences. Data collection involves examining the boiler’s design operation and nondestructive inspections. The macrograph revealed wall thinning due to impact from large slagging falling from the superheater division panel. This led to abrasion of the outer tube. Scanning Electron Microscope (SEM) testing highlighted abrasion fracture patterns, alongside metallographic findings of microstructural degradation. Consistent hardness test results showed values of 200–210 HV near the failure site. The chemical composition aligns with ASTM A213 T12 material standards. This analysis identifies falling slag abrasion as the primary damage mechanism in bottom slope tubes. The findings can aid in formulating effective strategies to prevent tube failures, optimize slagging cleaning frequency, and enhance boiler operation safety and efficiency through shutdown procedures and preventive measures.