Abstract: Failure-induced leakage occurred at the downstream spool of the AIC2502 primary valve in the catalyst regeneration system of an aromatics complex, which affected its safe operation. To prevent unplanned shutdowns or safety incidents caused by similar equipment failures, a systematic failure analysis was conducted through macroscopic examination, thickness gauging, process medium analysis, spectrographic analysis, material hardness testing and metallographic examination. The analysis results indicate that the primary damage mechanism involved welding-induced material degradation. Grooving corrosion and cracks were observed in the heat-affected zones (HAZ) of weld joints at both pipe ends, where stress concentration at welded regions facilitated further crack propagation. Based on the analytical conclusions, the paper proposes recommended measures such as material upgrades and welding process optimization to ensure the long-term safe operation of the aromatics complex.

Key words: catalyst regeneration, corrosion, failure analysis, damage mode