Applicability of mandrel elbows to high pressure gas pipelines is discussed in this paper taking into account the seismic integrity to withstand liquefaction-induced permanent ground deformation. Bending test and FE analysis of X65, 45 deg. mandrel elbow with diameter of 24-in were conducted in order to evaluate the seismic integrity for lateral spreading due to liquefaction.
Local buckling behaviors of the closing-mode test was simulated by FEA and calculation of existing seismic design code for high pressure pipelines can estimate maximum bending angle as limit state of the mandrel elbow conservatively. The results clarify that mandrel elbows can be applied to high pressure pipelines using conventional design method including the design code and FEA. In addition, buckling behaviors of the mandrel elbow were similar to those of high-frequency induction bends which have been used for high pressure pipelines in Japan.
