Failure Analysis of Two HP-Nb Heat-Resistant Tubes after 46,000 h Exposure to Reformer Service Conditions

This study presents a failure analysis in two reformer tubes used for hydrogen production petrochemical industry. These (Tube A and Tube B) were made by the centrifugal casting of HP-Nb alloy such way that one contained titanium as micro-element, other was free from its chemical composition. Although subjected to similar creep conditions, failed after only 46,000 h operation against design life 100,000 h. SEM images showed initiation growth pores next chromium carbide particles, well formation microcracks Cr23C6 carbides. Pore occurs result grain boundary sliding is strongly dependent on structural morphology. The tube containing higher thermal stability resistance than without A), which due finer more discrete particles. final fracture A) occurred coalescence creation cracks.