Effect of multi-steps expansion on UOE pipe quality through production process

The UOE manufacturing process is a widely utilized method for producing large-diameter steel pipes to meet the growing global energy demands. In the final stage of UOE pipe forming, the multi-steps process of the expansion creates overlap areas, leading to nonuniform distributions of residual stress, ovality, and plastic deformation along the pipe's longitudinal direction. This study aims to analyze the effects of two critical expansion parameters—overlap length and expansion ratio—on the structural performance of UOE pipes. A 3D finite element model of the UOE process was developed to simulate the nonuniformities caused by overlap areas. The model was validated using equivalent plastic strain (PEEQ) distributions from reference studies and employed to conduct collapse analyses using the Riks method. The findings suggest that, although the overlap length has a relatively smaller effect on collapse performance compared to the expansion ratio, the overlap areas exhibit significantly higher stress levels under external pressure. This highlights the importance of precise parameter control to enhance pipeline reliability.