Life Assessment of HP-40Nb Reformer Furnace Tube of a Petrochemical Plant

Reformer furnaces are an essential part of the petrochemical industry to produce hydrogen. Their most critical components are radiant tubes, where extreme temperature and pressure conditions require the high alloyed austenitic HP grade steels, owing to their excellent strength to creep rupture and corrosion resistance. Therefore, radiant tubes are the most critical components of reformer furnaces. Life assessment of cast 25Cr35Ni-Nb (HP-40Nb) reformer tube was performed. For this purpose, the nature of the damage and the experimental Larson–Miller diagram were used. The nature of damage of the tube in service was metallographically analyzed using optical and scanning electron microscopes. Samples from the serviced tube were cut and prepared for the stress rupture test at 900–1040°C under 20–30 MPa stress. Microstructure changes were observed with SEM. They included internal and external layer oxides, the network of carbides and isolated/ oriented cavities.