Failure Analysis of Furnace Tube

This article describes the findings of a detailed investigation into the frequent failure of ethylene furnace radiant tubes at a petrochemical plant. Thorough analyses including visual and stereoscopic examination, metallography, chemical analysis, and hardness testing show that the tube failure is attributed to creep accelerated by heavy carburization and uneven heating. The inability of the alloy to form a re-healing protective oxide scale led to accelerated carburization and nitridation. Possible factors that could adversely affect the scale protectiveness are discussed.