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Finite element analysis of JCO-E fabrication process and its influence on the material properties and collapse capacity of offshore pipelines

I. Gavriilidis ∗ , A. G. Stamou, S. A. Karamanos

Department of Mechanical Engineering, University of Thessaly Volos 38334, Greece

∗ ilgavrii@uth.gr

Keywords: cold-forming process, offshore pipeline, collapse

The JCO-E process is a commonly used process for fabricating large diameter thick-walled line pipes through cold forming/expanding processes. In particular, the initial flat configuration (plate) is deformed significantly in the inelastic range to obtain the circular configuration (line pipe) of the final product through a sequence of steps which involve: (a) crimping of plate edges, (b) “J”, C” and “O” steps where a punch is used to deform the plate and obtain a minimum distance (gap) between the plate edges (c) welding of plate ends to obtain a semi-circular geometry and (d) expansion to improve the geometry of the final product. The cold forming steps of the process (JCO steps) and the final expansion step affect the geometric (i.e., cross-sectional ovality, wall thickness) and material properties of the final product. The effect on the geometric and the material properties are important for the resistance to collapse of the fabricated pipe in the presence of extreme external pressurization, compared to seamless pipes [1], [2]. In the present work, the JCO-E fabrication process is numerically simulated using advanced finite element tools for the case of a thick-walled 30-inch-diameter pipe, which is candidate for deep water installation. Subsequently, the structural performance of the line pipe is investigated under external pressure in a unified approach. Uniaxial tests are performed to obtain the material properties used in the finite element model, which are representative of the loading history that the plate is subjected during the process. The effects of the forming parameters on the properties of the final product are investigated through extensive parametric studies. The results have shown that there exists an optimum expansion range for achieving the minimization of the geometric imperfections of the final product and the maximization of the collapse capacity of the pipe. The numerical predictions on the material properties and the collapse performance of the fabricated pipe are also compared with analytical-simplified methodologies. References [1] Herynk, M. D., Kyriakides, S., Onoufriou, A. and Yun, H. D. (2007). Effects of the UOE/UOC pipe manufacturing processes on pipe collapse pressure. International Journal of Mechanical Sciences, Vol. 49 (5), pp. 533-553. [2] Antoniou, K., Chatzopoulou, G., Karamanos, S. A, Tazedakis, A., Palagas, C. and Dourdounis, E. (2019). Numerical Simulation of JCO-E Pipe Manufacturing Process and Its Effect on the External Pressure Capacity of the Pipe. Journal of Offshore Mechanics and Arctic Engineering, Vol. 141 (1):011704

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