Project Overview
We recently completed a successful project for a client with a 60m diameter, 20m high storage tank storing kerosene. The tank exhibited severe ground-side pitting corrosion on the annular plate, particularly in the critical zone, affecting large areas. The client contacted us to assess whether the tank was still fit for service and to determine if it could continue operating at full capacity. If not, the goal was to establish an operating liquid height to keep stresses within acceptable limits and develop a repair strategy.
FEA Approach
Using SolidWorks Simulation, we conducted a detailed Finite Element Analysis (FEA) of the tank’s shell and bottom plate. Given the large diameter-to-thickness ratio, shell elements were employed for the tank walls to ensure computational efficiency and accuracy. To optimize computation further, only a pie-section of the tank was modeled, incorporating foundation interactions to accurately capture uplift effects at the annular ring area.
Several sensitivity analyses were performed to evaluate the influence of foundation stiffness, nozzle effects, adjacent plate thickness, and seismic uplift on the tank’s structural behavior.
Key Findings from the Analysis
The analysis confirmed that the annular plate required immediate repair due to the high corrosion rate, and that the tank would not survive the next three years without intervention. The structural integrity of the tank could not be maintained until the next scheduled inspection. While lowering the operating liquid height could reduce stresses, it was not a viable long-term solution.
Conclusion
Through Finite Element Analysis (FEA), we provided the client with a clear assessment of the tank’s condition and actionable insights for continued safe operation. By integrating advanced contact modeling and sensitivity analysis, we proposed effective strategies based on industry standards such as API 579. This project highlights the power of FEA in evaluating fitness-for-service (FFS) and ensuring proactive maintenance for large storage tanks.