Research Of Deformation Of X70 Pipeline In-service Welding

With the development of finite element and the progress of computer technology, many scholars are using numerical analysis technology and analysis software is used to solve the problem of welding. To avoid the risk of actual experiment and saving the cost, numerical simulation has a great advantage. The large commercial finite element software named SYSWELD is used to simulate in-service welding in this paper, and 3D finite element is established to the simulate the affect of influence factors in in-service welding process, analyze the influence of various factors of the welding in-service.The influence factors of In-service welding heat source is simulated, and compared the size of deformation of three kinds of welding heat source model, changing different cases, The deformation of Double ellipsoid heat source model of the welding is closer to actual situation. When choosing welding method and the device should try to choose the heat source of the double ellipsoid heat source model.3D finite element model is established, after load the heat source model, thedeformation of in-service welding was simulated under the conditions of different thicknessand pressure, draw a conclusion of relation schema among deformation, pressure and thewall thickness. Simplifies the model of in-service welding, and presented non-dimensionalparameters, obtained the scope of in-service welding safety through measurement andcalculation.The influence of some influence factors of in-service welding deformation issimulated and compared. The increase of welding speed, internal medium pressure, thedecrease of flow velocity makes welding deformation increases, the relative safety isdecline; Compared two kinds of molten pool shape to elaborate the influence of Moltenpool shape of in-service welding. relatively narrow and deep molten pool is better to adaptto the environment that pressure is larger, and is not easy to burn through, relatively wideand shallow molten pool is more prone to instability. Compared with actual weldingexperiment, the simulation results is relatively consistent with the actual situation, and the results is reliable.