The In-service Welding Experiments And Simulation Of Oil-and-gas Pipeline Pipelines

Pipeline distribution is the main measures of distributing oil and gas. As the service time increases, it will produce localized corrosion thinning or damage, There will be significant economic losses,casualties and environmental pollution once the pipeline failure accidents happed, so strengthening and welding on damaged parts of pipeline on the spot is necessary. Compared to the traditional pipeline pressure relief outage repair, in-service welding takes the advantage of short repairing time,fast speed and no pollution. It takes great economic benefits, social benefits and broad application prospect.Therefore, in-service welding repair has important theoretical significance and application value.In this paper, 06Cr19Ni10 material is the research object. This paper researched burnthrough which is the main problems of in-service welding, using numerical simulation method, combined with test. This paper studied the pipe pressure and the influence of welding parameters for welding burn by creating a static in-service welding test device and choosing different pipeline thickness. The study found 3mm wall thickness is the limit thickness of in-service welding. In this thickness, the impact and penetration of the welding specifications burn is greater than the internal pressure of the medium. This research simulated the 3mm security wall thickness of in-service welding by using ANSYS finite element software and found when the welding current is 110 A, the burn occurs, the results are consistent with the experimental results. By using SYSWELD finite element analysis software for 6mm wall thickness of the pipeline, this paper studed the stress on the in-service multi-pass welding temperature field-strain field impact and hardness of welded joint. To prevent intergranular corrosion, the temperature between layers need to be controlled. During the welding process the weld central portion of the steady-state stage of the tensile stress occurring mutations prone to burn, under internal pressure. For 6mm wall thickness of the pipe in service welding,SMAW and TIG welding molten pool model is established. The study found the critical pressure of burn of narrow and deep molten pool in TIG welding is 8MPa, while the wide and shallow molten pool type of SMAW still didn't burn through when the tube wall pressure reaches 8MPa. The research results can be used to determine the feasibility of in-service welding repair and guide the selection of welding parameters.