Numerical Evaluation of Mechanical Property Change and Collapse Strength of ERW Pipes Considering Manufacturing Process

Abstract

Along with the development of the energy industry, demand for oil and gas pipelines has increased, and as the low oil price era has been prolonged, more economical pipe design and construction are required. Typical examples are ERW pipes used as OCTG or reel-lay pipeline. The ERW pipe is made by passing the plate through continuous rollers, where repetitive loading and unloading causes unintentional plastic deformation and changes in initial steel properties. So, this study focused on both the change of mechanical properties during manufacturing process and collapse strength of ERW pipe considering the Bauschinger effect in order to produce more economical and high performance steel pipe. In this paper, the ERW manufacturing process was divided into three stages: forming station, sizing station, and flattening station. The ERW manufacturing process was simulated as 3D nonlinear finite element models using ABAQUS (6.14-1). Then, the change of mechanical properties at each process station was examined through finite element analysis and PEEQ, Alpha, and residual stress in each process station were evaluated for maintaining continuity of analysis. And flattening station where the reverse bending gives a large change in the mechanical properties was also performed. Finally, the collapse strength of the ERW pipe was evaluated in consideration of the change in compression strength during the manufacturing process. The ABAQUS analytical model was verified by showing analytical results to be identical with the outer diameter measured from the full-scale size pipes. Using the developed analytical model, it is possible to numerically predict the mechanical properties and collapse strength of ERW pipe.