Theoretical analysis of elastic collapse in metallurgical clad pipes under external pressure

Metallurgical Clad Pipes (MCPs), due to their unique manufacturing process and excellent corrosion resistance, are key equipment for transporting highly corrosive oil and gas in offshore systems. However, the high external hydrostatic pressure in deep-sea environments poses significant risks of collapse, threatening the structural safety of MCPs. In this research, the elastic collapse performance of MCPs under external pressure is investigated by deriving a novel analytical formula based on Donnell shell theory and the Ritz method. The proposed formula considers the perpendicularity of pressure during deformation and is validated through comparisons with the DNV-ST-F101 formula and FEM simulations. The findings demonstrate that the elastic post buckling equilibrium path of MCPs follows the same pattern as that of conventional single-metal pipelines. Moreover, the proposed formula shows improved accuracy and greater applicability to various geometric properties and materials. Research works may provide a theoretical basis to improve the design and safety of MCPs and contribute to the ongoing development of offshore pipeline engineering.