Study On Sealing Technology Of Seabed Pressure-retaining Sampling Device

With the continuous consumption of land resources,marine mineral resources have gradually become the direction of research and development in various countries.There are a lot of mineral resources in the ocean,and most of them exist in the geological soil at the bottom of the ocean.The environment is complex and the development is difficult.In order to accurately explore the content and distribution of seabed mineral resources,and to further study and analyze the collected mineral samples,the sealing device on the sampling equipment should have good sealing and pressure-keeping performance,so as to ensure that the samples are kept in the same storage environment as the seabed pressure conditions during the whole working process from the completion of collection to transportation to the surface investigation vessel,so as to avoid it.Because the pressure changes affect the physical and chemical properties of the sample.Based on the research results of sealing methods at home and abroad,this paper designs and studies the pressure-retaining pipe and the sealing device on the fast-clip pressure-retaining drilling tool in the seabed pressure-retaining sampling equipment.In this paper,the application of conical seal on pressure retaining pipe is studied,and the principle and condition of conical seal are determined.By establishing a three-dimensional simulation model of pressure-retaining pipe and using ABAQUS finite element software,the contact stress and strain of the metal contact surface of the conical seal of pressure-retaining pipe under the condition of design parameters were numerically simulated.The influence of two main parameters,the metal material of the contact conical surface and the inclination angle of the conical surface,on the sealing performance was analyzed.According to the simulation results,the maximum contact stress on the sealing contact cone decreases with the increase of the angle of the cone,and the sealing performance decreases gradually,so the cone angle of 60 degree is the most suitable one.In addition,the material of plug and core pipe is selected separately: copper and common carbon steel,the strength and mechanical properties of two different materials are different.Sealingeffect of lifting conical seal.In this paper,the three-dimensional model of local sealing structure at both ends of fast clamp pressure retaining drilling tool is established,and the stress on the sealing ring is numerically simulated by ABAQUS finite element software.It is concluded that the working pressure in the core pipe is less than 25 MPa,and the sealing rings at both ends can effectively seal the drilling tool.In addition,the structural strength of the main parts of the drill tool,such as the lower packing end cap,pin and bush,was checked,and the improvement measures were put forward.Based on the above theoretical design and analysis,the design and improvement of the sealing device on the pressure retaining pipe and the fast card pressure retaining drilling tool are completed.Processing and manufacturing are carried out according to the design results.Sealing performance of the three test and analysis devices is analyzed through step-by-step pressure test,holding time test and simulated holding pressure test of sediment environment.According to the test results,it is concluded that both the pressure-retaining tube test device and the fast-clamping pressure-retaining drilling tool test device have good sealing and holding capacity,which further confirms the reliability and tightness of the simulation results.The practical feasibility of the sealing device.