**4. Discussions**

Pipeline is an important part of equipments, which is widely used in petrochemical, aerospace, and other industrial applications, and is extremely important in safe production. There are unavoidable erosion and corrosion during applications, which maybe lead to leakage of the pipeline because of harsh working environments [14–18]. The main reasons of leakage are erosion, electrochemical corrosion, turbulent and chemistry, and their interactions. Corrosion is one of the most damaging mechanisms in many engineering materials and structures. Erosion of the pipelines may result in the failure of the piping system, which can be extremely dangerous and expensive. Erosion may enhance corrosion and corrosion may enhance the erosion rate through preferential dissolution and this is the so-called synergistic effect. It is well-known that, because of the synergistic effect, the possibilities of leakage are generally much higher than the sum of pure electrochemical corrosion and pure mechanical erosion. Moreover, elbows are the weak parts of gathering and transferring pipelines. In studies of erosion–corrosion there are no models available which attempt to combine the effects of particle erosion, electrochemical corrosion, chemistry, and fluid flow [19]. Nowadays, because of a strong demand for the analysis of erosion–corrosion problems, this study focuses on the following aspects: numerical study on the fluid flow, erosion, and corrosion along the axial direction of the pipeline for the real field cases and the related phenomenon of erosion–corrosion expecting to provide detailed and reasonable analysis of the failure incurred by the erosion–corrosion.
