Failure investigation on reheater pendent tubes due to external scale exfoliation and internal scale formation

Abstract

This paper presents failure investigation on reheater pendent SA213-T22 tubes through visual inspections, steam-side scale and tube wall thickness measurements, metallurgical examinations, and creep analysis. The investigations were carried out following subsequent tube failures of the reheater pendent region of a boiler unit. Interaction event of significant internal scale formation causing the higher metal temperature and external scale exfoliation as a result of high-temperature corrosion is identified to cause the failure of the reheater pendent tube. Prevention actions are recommended to avoid similar failures in the future. © 2011 American Society of Mechanical Engineers.