Research On The Grouting And Baglaying Device For The Treatment Of Submarine Pipeline Suspended Span

Submarine pipeline is the lifeline of offshore oil and gas fields, but due to the complexity of the marine environment, the submarine pipelines are often carved out the cover and form the suspension under the action of wave, current, seabed geological conditions and other factors. Suspended span not only makes the pipeline to bear a greater additional bending moment load, but also is easy to form vortex induced resonance with the flow action, which will speed up the damage pipeline. Therefore, before the suspension span forming and achieving the maximum allowable length, it needs to take measures to control the span.This topic originates from the sub project of CNOOC Tianjin about the research on monitoring and treatment technology of submarine pipeline span - the design of processing device for submarine pipeline suspended span. The purpose of the project is to design a kind of processing device, which is based on the research of pipeline suspension technology.In this paper, it introduced the influencing factors on the submarine pipeline suspended span and the processing technology of submarine pipeline suspension at home and abroad.Through the analysis and comparison of spanning processing technology and combined with the design of the subject requirements, it was ultimately decided to select the grouting bag method to process the pipeline suspended span, and proposed the overall scheme design of the processing device of grouting bags.Due to the grouting bag is the most important bearing member in this designing scheme,the Morison equation was adopted to analyze the wave flow load characteristics around the grouting bag under the water, and mechanical model of the grouting bag has been established.It has also analyzed the various elements influencing on the load of wave and the stability of the grouting bag when it is under the condition of the maximum load. Meanwhile, a structure was designed to make the routing bag can be raised again, and the scour law was analyzed,which provides the research foundation for its undersea applications.In this paper, the main structure of the processing device was designed, and the bearing capacity of the key parts of the mechanism was analyzed and calculated. Also the strength of these parts was checked by the finite element software. In view of the problem of the stress concentration of components, the optimization design of the structure was performed. In addition, motion performance of the support and locking mechanism was simulated.According to the design scheme of the processing device of grouting bags, the engineering prototype was finished. Also the experimental results were carried out, and the time was measured for the device to complete some actions, which provide the experimental basis for the sea test. Moreover, the air test of the grouting bag was carried out, which verified the pressure capacity of the grouting bag and ensured the reliability and safety of the work.