Research On Seabed Pipeline Mechanical Expanding Machine

Seabed Pipeline is the necessary key technology equipment of offshore oil and gas development and transportation. Seabed Pipeline requires extremely high mechanical performance due to special marine environments such as long-term sea tide, waves impact, seabed geological subsidence, high pressure against outside of the tube and seawater corrosion. Seabed Pipeline is adopting step-wise stamping forming, is constructed by double-sided submerged arc welding process, which not only easily to form the bauschinger effect in the molding process, to lower the yield strength of the material, but also severely to affect the roundness and straightness of Seabed Pipeline. Therefore, we need to use mechanical expanding machine to expand the Seabed Pipeline, to reduce the bauschinger effect, and to raise the yield strength and dimensional accuracy. At the same time, the welding quality could be examined.At present, the domestic Seabed Pipeline mechanical expanding machine mainly depends on foreign imports. In order to break the international technology monopoly and blockade to the mechanical expanding machine, a design for Seabed Pipeline mechanical expanding machine unit with a diameter 406-1422 mm, wall thickness 6-40 mm, tube length 9000-18400 mm, the highest material X100(?s?840MPa) is made according to market demand. The main contents in my thesis are as follows:Firstly, overall parameters are designed to mechanical expanding unit according to the mechanical expanding objects and goal; also functional design is made to mechanical expanding unit components such as steel tube input, output roller, steel tube flushing device before and after expanding, steel tube sliding car device, the main expanding device, etc. according to overall parameters.Secondly, according to the operation principle and structure form of mechanical expanding machine head, numerical simulation is made to Seabed Pipeline mechanical expanding forming process by use of finite element analysis software. A stress & change rule analysis is made in the process of mechanical expanding. Meanwhile, an optimization design is made to expanding head referring to failure reason of expanding head in the process of engineering application, then to verify the application effect of optimization design by applying the experiment.Finally, the calculation formula of expanding rod force and expanding unlock force is elicited and the effectiveness is tested according to force analysis of pull rod in the process of Seabed Pipeline mechanical expanding. Meanwhile, an optimization design is made to pull rod referring to failure reason of pull rod in the process of engineering application, and to verify the bearing capacity of pull rod by fatigue life experiment under environmental load effective of rod gap style.