Research On Safety Performance Of Deep Water Riser Coupling Flange System

Deepwater drilling riser flange, which is an important equipment underwater pipelines connection, will directly affect the stability and safety of offshore drilling vessel or platforms. To keep the risers and other equipment of flange connections operating safely, the strength of the overall structure, sealability of connection, and the capability of assembling and disassembling must be ensured. However, drilling environmental conditions becomes more complex with the water depth increasing, and riser flange stress state is also more severe and complex. The issue of the connect device’s strength and stability whether adapt deepwater drilling has not been systematically studied in the country. Therefore, the further study of the safety performance of deepwater drilling riser flange system is very important for reducing production safety accidents on drilling platforms, and drop losses on offshore drilling work.The research started from mechanical properties. We have tested the flange connection joints under three types of situation. To research riser joints of stress levels under different preload conditions and sealability and deformation properties under hydrostatic test pressure conditions. Therefore, we have launched a series of finite element analysis, experiment measuring and a comprehensive comparative analysis.First, through the analysis of load acting position of flange test., considering the stress level and welding process and the rated load tensile test and hydrostatic test requirements, design two test device to meet the test requirements. And test the devices by finite element simulation, and the strength and stability will also be checked. Though the three aspects of device stress distribution, manufacturing process, manufacturing cost, conducted comparative analysis of test equipment to find the relatively suitable test device structure.Secondly, build the 3D model of riser flange joints by using SOLIDWORKS. Through the stress calculations of flange and bolt, analyse the distribution of stresses in the flange preload test, tensile test and hydrostatic test by Finite Element Simulation. Select the section position of the stress strength check, and select Assessment path in the flange area of stress concentrated and flange wall thickness change region. Compare the flange linearized stress results in different paths with the corresponding allowable stress.Finally, through field trials which are test for preloading load test, tensile test and hydrostatic test. analyse riser joints of stress levels under different preload conditions and sealing and deformation properties under hydrostatic test pressure conditions. According to the test results of comparative analysis of the measured and finite element simulation, considering the simulation and the reasons for the existence of errors in the trials, find the main error of the difference between the simulation and the trials results. The obtained results show that the experimental data and numerical simulation results have good consistency. FEM simulation calculations can replace the flange test with riser flange test device, and the safety performance research is substantive significance, and can provide confirmatory guarantee on safe reliability in deepwater pipe flange system.