Research Of Submarine Pipeline Protection Concrete Removal Technology Using High Pressure Water Jet

In China, increasing length of paved submarine pipeline as well as their reducing life time result heavier maintenance and repair workload, hence, the need for removing submarine pipeline protection concrete keeps increasing. It is urgent to accelerate the independent research and development of submarine pipeline protection concrete removal technology and equipment, which is not only significate meaningful to our country's submarine pipeline repair technology, but also an active response to the requirement for developing the offshore repair equipment and system in the 13th Five-Year Plan.Based on previous advanced technology abroad and the domestic existing technical conditions, this study explores the submarine pipeline protection concrete removal systems which are suitable for national conditions. It particularly complete the design of submarine pipeline protection concrete removal equipment, which is the key part of this system.The planning process of the submarine pipeline protection concrete removal engineering has determined at the very beginning, afterwards the feasibility experiment of broken concrete in submerged environment using high pressure water jet has been verified, and reasonable processing parameters are obtained, thus the functional requirements and the main parameters of protection concrete removal equipment have been determined.Based on the requirements proposed above, this paper accomplishes the mechanical structure design of protection concretes removal equipment for submarine pipeline, including the design of equipment framework, slewing mechanism and clamping mechanism, then conducts detailed mechanics analysis and calculation. Meanwhile, this paper devises the overall scheme of hydraulic system, also the calculation and selection for both hydraulic actuators and hydraulic control elements are given. It is able to rotate 360 degrees and crawl automatically on the pipeline to remove concrete completely, which fully meets requirements.Finally, using numerical analysis provided by FLUENT, effects on high pressure water jet caused by submerged environment is studied with respect to that caused by air ambient, also influences on submerged jet's dynamic pressure and velocity caused by nozzle diameter, ambient pressure and jet pressure are discussed, so that to provide theoretical support for using high pressure water jet to remove submarine pipeline protection concrete in different water depths.