Analytical Study of Appropriate Design for the High-Grade Induction Bend Pipes Subjected to Large Ground Deformation

In this study, the deformability of induction bends made out of high-grade line pipe is analytically discussed. In order to clarify the significant parameters for the deformability, 30 cases of finite element analyses simulating the deformation behavior subjected to internal pressure and bending moment were carried out. The effects of the mechanical properties, the geometry of the “bend” part and the properties of the “transition” part on the deformability were investigated. Finally, the change in the integrity of the buried pipeline due to the quality of the induction bend was quantitatively examined. The results showed that the effects of the mechanical properties and geometry of the “bend” part on the deformability were small in the closing mode. On the other hand, the deformability was sensitive to such parameters in the opening mode. Especially, the properties of the “transition” part were significant. Consequently this study indicated that the mechanical properties, the dimensions and tolerance and the properties of the “transition” part should be appropriately designed in proportion to the amount of assumed ground deformation.