Design Of The Casing Pipes Centering Equipment

The casing pipe is widely used in offshore oil exploration and other offshore activities. Its main function is to insulate sea water so as to form circulation channel for drilling fluid. At the same time, it serves as the bearing structure of wellheads. With the development of offshore oil enterprise, the number of the projects carried out in deeper water is highly increasing; consequently a high efficient approach to installing the casing pipes on the vessel frame equipped in deeper water is urgently needed. In order to lower the requirement for the sea state conditions and enhance the working efficiency, Ocean Casing Pipes Centering Equipment has already been designed and implemented. The equipment is a device which is used to weld the casing pipe in segments. It can automatically carry out clamping and centering two casing pipes, then welding of two pipes is operated in the middle part of the equipment. The centering equipment can effectively resist the impact against the pipes and wellheads due to wind, ocean current, waves and etc.. Furthermore, it provides much convenience in installment, taking-down and centering.The equipment comprises three parts:main-machine, hydraulic system and electronic control system. In the development of the equipment, the digital design method is made use of. All the parts and asembly 3D model are constructed applying ProE software which is parametrization modelling. The structure of main-machine mainly includes frame-work, right clamp holder, left clamp holder, guiding plate, supporting block. The frame-work is composed of four semiannular beams, three steel pipes, two arch plates and some ribs, and it's strength and stiffness have to be adequate so as to the centering precision can be guaranteed. For the equipment being applicable for clamping different size casing pipes, there are three kinds of supporting blocks which can replace each other while clamping different size pipes(diameter respectivelyφ762mm,φ610mm,φ508mm). Being a large-sized welding steelwork, the main-machine is 5620mm high, and maximal cross section diameter is 2400mm.Tthe finite element model of non-linear contact of 3-D elastic-plastic feature of the ocean casing pipes centering device is constructed. Since the ProE and ANSYS can link together seamlessly, the model custructed in ProE can be transformed to ANSYS preprocessor directly. Owning to symmetry of the model, only a quarter of the model is analysed. In conclusion, the centering equipment meets the design requirements. Design of the hydraulic and control system was fulfilled in this paper. The hydraulic system contains eight cylinders, two pairs of cylinders which are in charge of opening and closing the clamp holders. The hydraulic system has two control modes, manual and semiautomatic mode. The electronic control system is simple correspondingly, and the hydraulic system under the control of PLC CPM2A can implement all kinds of action needed in operating.