Modeling of mechanical behavior of corroded X80 steel pipeline reinforced with type-B repair sleeve

This work investigated stress response of a corroded X80 steel pipeline repaired by a type-B sleeve to internal pressure by finite element modeling. Firstly, a three-dimensional numerical model of corroded pipeline reinforced with type-B sleeve was developed, and its accuracy and reliability were verified by the burst test results and the theoretical analytical solution, respectively. Second, the von Mises stress of the pipe body, sleeve and fillet weld was simulated under various affecting factors, i.e., internal pressure, corrosion defect dimension (depth, length and width) and sleeve length. Finally, a parameter sensitivity study was conducted to determine the effects of corrosion geometry and sleeve length on the repair efficiency. The main investigation results show that the type-B sleeve repair method is effective to restore the pressure-bearing capacity of the pipeline at the corrosion defect, and the burst failure of repaired pipeline always occurs at the region far away from the defect and sleeve. At the limit state of burst, the local defective region shows the highest stress, followed by the fillet weld, and the repair sleeve has the smallest stress, thus the maximum equivalent stress of the corroded zone is suggested to be used for measuring the repair efficiency of the repaired pipe by type-B sleeve. The sleeve-repair effectiveness is affected by depth of the corrosion defect, a deep corrosion defect reduces the performance of the sleeve repair compared with a shallow defect. The effect of the corrosion defect length on sleeve repair depends on the defect depth. Furthermore, there exist a critical length of the defect that affect the repair efficiency. The corrosion defect width shows limited effect on stress level at the defect of the repaired pipe. At last, a new method based on stress analysis is proposed to optimize the sleeve length for repairing a corroded pipeline.