In this study, dynamic analysis and model tests were performed for the installation of a flare tower using two floating cranes. The dynamic analysis system is developed based on the multibody equations of motion by considering external forces such as wave, wind, current, mooring, and wire rope forces. Numerical integrator for solving equations and static analysis for finding the initial position and orientation are provided in the system. The user interface including modeling function, scenario setting function, and result analysis tool is provided. The dynamic analysis was validated by the model tests for the same installation equipment and procedure. The installation is to turn-over the flare tower by controlling boom angle and wire rope length using two different sized floating cranes. We compared the both results of the dynamic analysis and the model tests about the 6-DOF motions of the floating cranes and the flare tower, and the tension of the wire ropes and the mooring lines.
Offshore cranes are being used for the purpose of installing, dismantling and maintaining offshore plants. The weight of the offshore plants are increasing as the scale of the offshore plants grow. Therefore, large offshore crane or multiple offshore cranes must be used to install offshore plants. In case of using one large-sized offshore crane, there is an advantage that the installation operation can be performed stably, however, there is a disadvantage that it is difficult to move and a large installation space for mooring is required. Therefore, in areas where it is difficult to use a large offshore crane, two small offshore cranes should be used for the operation. In the case of using multiple offshore cranes, it is advantageous that it is easy to move and a small installation space for mooring is possible. However, safety is more important than the operation of large crane because two floating cranes should be cooperated. Therefore, it is necessary to perform the analysis work to evaluate and verify the safety in advance for the cooperation operation of multiple offshore cranes.
