Design And Characteristic Research Of Submarine Pipeline Repair Connector

Submarine pipeline is the main component of offshore oil and gas development and production system,and once submarine pipeline failure occurs,it will not only cause transportation interruption and shutdown,but also destroy the marine ecological environment.At present,domestic submarine pipeline repair field relies heavily on foreign technology and equipment.Therefore,this paper focuses on the deep-water pipeline repair technology,and designs a new submarine pipeline repair connector with water depth of 1500 m and 12 in pipe diameter.According to the technical specifications of submarine pipeline repair connector and the characteristics of deep water environment,a new type of submarine pipeline repair connector structure scheme suitable for deep water pipeline replacement and maintenance process is proposed.The design of connector anchoring mechanism,sealing mechanism and driving locking mechanism are completed.On the basis of static analysis,the specific relationship between driving force and anchoring pressure is established,and the formula for calculating the embedded depth h of anchoring clamping teeth is deduced based on the theory of elastoplastic mechanics.According to the special working environment of the connector,the equivalent friction coefficient is introduced to check the strength under the condition of maximum external load.The orthogonal test method is used to optimize the key parameters of the anchoring mechanism,and the optimal parameter combination is obtained.The maximum equivalent stress of the pipe at the bite of the tooth tip is reduced by 16.5%compared with that before optimization.According to the special working environment and sealing performance requirements of the connector,nitrile rubber is selected as the material of sealing ring,and the sealing ring structure is designed;based on the theory of elasticity,the mechanical model of sealing ring free deformation and constraint deformation stage is established,and the relationship between sealing driving force and sealing contact stress is obtained.Two improved schemes of inverted angle and fillet combined sealing ring are proposed,which can effectively improve the sealing performance,and the inverted fillet combined sealing structure has better comprehensive characteristics.Based on the theory of fluid mechanics,the vortex-induced phenomenon caused by the change of fluid flow pattern inside and outside the pipeline is studied.The flow state is determined by analysis,and the vortex shedding frequencies f_k and f_s of the fluid inside and outside the pipeline are calculated.The modal analysis of the whole pipe section repaired by the connector are carried out by using ANSYS software.The results show that the whole pipe section repaired by the connector will not resonate with the external excitation,and the connector has excellent working performance.The new submarine pipeline repair connector developed can be installed in deep water without submersible,has the characteristics of safety and high efficiency,can meet specific working conditions,and plays a guiding role in the subsequent development of a series of submarine pipeline repair connectors.