Submarine pipelines are prone to developing flaws, such as ellipticity and depression during the manufacture, burying, and use processes. The local buckling characteristics of submarine pipelines with initial imperfection must be studied since the initial imperfection have an impact on local pipeline buckling. In this study, the local buckling of submarine pipelines with varying depression depths and ellipticity is simulated using the finite element program ABAQUS, and defect sensitivity of submarine pipelines with varying shape ellipticity, varying depression depths, and varying pipe radius-thickness ratios is examined. Meanwhile, research is being conducted on the combined load buckling of a submarine pipeline with initial imperfection caused by bending, axial force, and external hydrostatic pressure. The results indicated that the critical external pressure of the pipeline is sensitive to the imperfection, although the buckling propagation pressure is not. The buckling morphology is influenced by the shape and size of the imperfection. Additionally, the ability to withstand external hydrostatic pressure of the pipeline reduces after it has been bent.

Storage tanks with partition plates are widely used in the petrochemical industry. However, relevant standards do not propose corresponding design criteria and methods for this type of structure, and theoretical design formulas cannot be applied to ensure the reliability of its structure. Therefore, it is necessary to analyze and design the storage tank with a partition plate by using finite elements. This paper studies the problem of buckling depression and cracks in the welded parts of the S-shaped tank with a partition plate during its operation. We used the finite element software ANSYS to analyze the overall strength and stability of the structure and obtain the larger stress area. Based on this, a safe and economical optimization plan is proposed: under the condition of strictly controlling the liquid level difference on both sides of the partition, the tank structure is optimized by adding stiffeners and tie rods. The study revealed that the measure effectively improves the overall rigidity of the tank body and reduces the maximum stress of the structure and enhances the safety performance of storage tank. Additionally, it provides a reference for the structural strength design of storage tanks with partition plates.

When the buried pipeline passes through the permafrost zone, the phenomenon of frost swelling occurs in the permafrost zone, which causes a certain degree of bending and deformation of the pipeline. As a result, the pipeline’s structural safety is compromised, and the pipeline finally fails during operation, posing a serious hazard to the natural gas pipeline’s operation. Whereas the theoretical research on soil frost heave is relatively comprehensive, the applied research on engineering problems is not yet complete. Therefore, it is necessary to predict frost heaving through experiments and numerical simulation, and put forward reasonable control measures for existing or potential problems. For the problem of pipeline damage caused by frost swelling of soil in the natural gas high-pressure regulator station in a river and creek region, the Drucker–Prager elastic-ideal plastic model of soil was selected for finite element analysis, and a reasonable finite element model of pipe-soil was established in this paper. Through the temperature field analysis, it was found that the soil around the buried pipe is affected by the pipeline and is lower than its freezing temperature, which makes the soil freeze and swell. Furthermore, through the thermal–structural coupling analysis, it was found that the buried pipe is affected by the freezing and swelling of the soil and the structure is greatly likely to be damaged. In addition, by analyzing the temperature distribution and frost heave deformation of the soil around the pipeline, as well as the deformation and force of the pipeline at different pipe temperatures, this paper also determined the ideal temperature for preventing frost heave damage to natural gas at high-pressure regulator stations as −1 °C. Finally, based on the results of the abovementioned analysis, the heating method was determined to improve the frost damage phenomenon at the high-pressure regulator. The results of the anti-frost and swell study were used to conduct field trials at natural gas high-pressure regulator stations where frost and swell had occurred. By adding heating furnace to increase inlet temperature, frost heaving of gas transmission pipeline can be effectively prevented. The results of the research provide a reference for both existing and new natural gas pipelines, and also accumulate experience for winter maintenance design and construction of pipeline engineering in seasonally frozen soil areas.

In this paper, the spatial and temporal damage evolution was described during crevice corrosion through developing a two-dimensional (2-D) model. COMSOL code was used to simulate the crevice corrosion regulated by the I∙R voltage of nickel (Ni) metal in sulfuric acidic. The electrode deformation, potential and current curves, and other typical characteristics were predicted during crevice corrosion, where results were consistent with published experimental results. Then, based on the Ni model, the damage evolution of X100 crevice corrosion in CO₂ solution was simulated, assuming uniform distribution of solution inside and outside the crevice. The results showed that over time, the surface damage of Ni electrode increased under a constant applied potential. As the gap increased, the critical point of corrosion (CPC) inside the crevice moved into a deeper location, and the corrosion damage area (CDA) gradually expanded, but the threshold value of corrosion damage remained almost unchanged. The CDA inside the crevice extended toward the opening and the tip of crevice. Since the potential drop in this region increases with increasing current, the passivation potential point moved towards the opening. As the gap increased and the electrolyte resistance decreased, the critical potential for reaching the maximum corrosion rate moved into a deeper location. It is significant for predicting the initial damage location and the occurrence time of surface damage of crevice corrosion through the 2-D model that is not available through the one-dimensional simplified model.