The Evolution and Determination of Mechanical Properties During the Manufacturing Process of High Strength Spirally Welded Pipe

During the development of high strength and high toughness spirally welded pipe with improved weld heat affected zone toughness, the evolution of the mechanical properties were studied by testing at different stages of the manufacturing process. The mechanical properties were measured in the as-welded condition after the spiral seam welding, after the hydrostatic test and after the aging cycle simulating the external pipe coating process. The tensile properties of the pipe body in the transverse-to-pipe-axis (TPA) orientation, as required by the CSA Z245.1 and API 5L standards, were determined using different test methods and different specimen geometries, such as flattened strip specimen, non-flattened round-bar specimen and ring-expansion specimen. The investigation results provided some insights into the development of the mechanical properties of the final pipe products and the methods for more realistically and reliably determining the tensile properties of the pipe along the circumferential direction.