Experimental and simulative failure analysis of reformer furnace outlet manifolds serviced in aromatic plant

Reformer furnace hot outlet manifold is a critical component in aromatic plants. Unfortunately, a hot outlet manifold used in Nanjing YPC Refining & Chemical Co., Ltd. failed after it has been in service for only 2. years. In the present paper, a failure analysis of the failed hot outlet manifold was performed by careful visual observation, mechanical properties tests, chemical content examination, microstructural analysis and microchemical analysis of fine precipitates. Finite element method (FEM) considering creep effect was also employed to define the evolution of critical region. Experimental results showed that the failure was a combination of overheating and high stress concentration. Exposing it to excessive temperatures at high stress significantly accelerated the creep rate, thus, leading to the premature failure. FEM analysis showed that hoop stress generated by the work inner pressure was the main reason leading to the crack initiated and propagated along axial direction of the manifold. Moreover, sequence of the failure region achieved by the simulation correlated well with the experimental analysis. To prevent the failure, better control of operating temperature was strongly recommended.