Study on erosion wear mechanism of natural gas elbow pipe with uneven corrosion defects

Due to erosion and corrosion, natural gas pipelines can be easily damaged, causing uneven corrosion defects on the inner surface of the elbow. The existence of uneven corrosion defects will affect the surface structure of the inner arch of the elbow. In this paper, the influence of uneven corrosion defects on the further corrosion of elbow was studied by computational fluid dynamics (CFD). The results show that the particles are distributed in a regular V-shape after hitting the outer arch of the non-defect elbow. However, part of the particles bounced irregularly after hitting the defect elbow, forming an irregular particle trajectory region. The uneven corrosion defects that have been created can affect the particle trajectory distribution. When the axial angle α is 45°–55° and the hoop angle φ is between 60° and 120°, the erosion of defect elbow is easily affected by corrosion pits. In addition, the maximum erosion rate of non-defect elbow can be increased with the increase of particle diameter. However, in terms of the impact of particle diameter on erosion, there are two inflection points in the maximum erosion rate of the defect elbow, showing the trend of “increase,”“decrease” and “increase.” The research can provide a theoretical support for subsequent engineering applications.