| New offshore oil and gas reserves are increasingly contributing to the growth of the world’s oil and gas reserves,especially the exploitation of oil and gas in deep-water.Subsea pipeline is an economic,reliable and safe way to transport offshore oil and gas resources.Flange connection is the most common method for subsea pipelines connection.The bolt flange connecting tool is an essential equipment in the process of deep-water pipeline bolt flange connection.The research is sourced from national major research and develop project and ministry of industry and information technology(MIIT)project.It is required to design a set of bolt flange connection equipment for pipelines in 1500 meters water depth,break the technical blockade of foreign countries,improve our national technical level in the field of deep-water oil and gas development,and reduce the cost of offshore oil and gas explotitation.The paper reviewed the current situation of domestic and foreign research on deep-water bolt flange connecting tool.The technical requirements and corresponding technical parameters of connection of pipe flange have been determined.The general design method of the tool is proposed.The modules of bolt magazine,nut magazine and tensioner magazine are analyzed and studied.The operation flow of the tool was proposed.Aimed at the alignment of bolts,nuts and tensioners,a position adjustment mechanism is designed to realize the synchronous circumferential rotation of bolt library,nut library and tensioner library,so as to ensure that the bolt,nut and tensioner remain coaxial at all times.The hydraulic cylinder and hydraulic motor are designed and selected,and the strength and stiffness of important components are checked to ensure the rationality and reliability of the structure.A nut-carrying fixture is designed that combined with the requirements of pipeline flange connection and the complex operating environment of deep-water.It can fix the nut and realize the accurate docking of the bolt and nut.Using the theory of multi-rigid body kinematics,the error model of the bolt-flange connection tool for deep-water pipelines is established,and the error simulation calculation is carried out to obtain the influence of each structural parameter on the alignment accuracy of the bolt and nut,and the optimization sequence of each structural parameter is determined.The error matching design method carries out the error matching design of the deep-water bolted flange connection equipment.The error matching design reduces the machining accuracy on the premise of ensuring the centering accuracy of the bolt and nut,and improves the economy of the connecting machine.In order to verify the correctness of the error matching design,the bolt and nut offset measurement was carried out after the assembly of the deepwater pipeline bolt flange connection machine,and the measurement times were 20 times,all is consistent with the calculated results.The bolt lead-in nut process process is analyzed,and the mathematical model of process of the bolt-nut collision is established.The dynamics simulation software is used to simulate the dynamics of the operation process,and the data related to the speed and displacement curve of the nut-carrying fixture and the collision force curve of the nut and the bolt during the bolt preload process are obtained,and the minimum distance of the nut from the edge of the nutcarrying fixture in the initial state is determined.The synchronization of the drive motor in the bolt preload process is studied,and an adjacent cross-coupling synchronization control scheme is determined.A mathematical model of the valve-controlled motor position servo system is established,and the controller is designed by a new exponential convergence law sliding mode control method.A set of prototype of the tool was developed,and the test system of prototype was built to conduct experimental research on the tool,including land test,tank test and sea trial.The results of the land test showed that the tool can complete the accurate connection of the pipe flange,and the connected pipe flange can maintain a reliable seal;the tool can complete the reliable connection of the pipe flange in the under-water environment under the monitoring of the remote video system and the operation of the diver is shown as the results of the tank test;the results of the sea trial had been showed that the tool can complete the reliable connection of pipe flanges in the complex marine environment only with the operation of ROV. |
