Abstract:For the purpose of solving the problem of fatigue failure caused by the submarine pipeline of phenomenon of free span, the research of grouting bags device was done, and its overall plan that once hoisting working can fill several suspended span was put forward and introduced the work principle. By using three dimensional (3D) modeling, stress analysis and the finite element method (FEM), the lift mechanism used for pallet was designed to determine the hydraulic cylinder parameters. According to the synchronization requirements of the hydraulic cylinders on both sides of the device, the synchronous circuit design and simulation analysis of the hydraulic cylinders controlled by propotion integral and differential (PID) were carried out, and the PID parameters were determined by the method of trial and error. In the end, the prototype was made, and the experiments of the lift mechanism of stretching out and pulling back were carried out. The results verify the rationality and feasibility of design. The device can replace divers to fill several submarine pipelines of suspended span parts once at a time, and improves the working efficiency; therefore, it will have a definite meaning in engineering application under the sea.