Research On Subsea Pipeline Repair Coupling

Subsea oil pipeline fast repair technology is an important research topic to ensure normal production of offshore oil and gas, foreign countries have successfully applied this technology to engineering, developed a variety of couplings, which can be competent to various pipeline's repair. The research for China's subsea oil and gas pipeline repair couplings is of great strategic significance, which will be helpful to improve energy economic efficiency, and promote the development of relevant marine engineering technology as well.This paper focuses on the research of subsea oil pipeline repair couplings, including seal principle, structural design and optimization, connection reliability, etc. Firstly, with contact seal theory, couplings'seal problem has been solved. Seal theory also is the basis of connection reliability analysis and structural optimization. External impact factors which affect couplings'seal capacity in practice also is discussed in this paper. The approximate elasticity solution of pipeline with pressure ring is obtained using axisymmetric elasticity theory.8-inch subsea oil pipeline repair coupling structure is designed and optimized with CAE, the best couplings'seal capacity and minimum press force are obtained successfully by changing structure dimension.Finally, the probability of reliability is researched because of the randomness of pipeline. Based on theory of reliability, the seal capacity and maximum press force's sensitivity to pipe diameter, wall thickness and material yield stress is calculated using Probability Design System in ANSYS. The couplings'reliability is obtained with stress-strength interference theory, as well as the reliability of entire oil pipeline.