On the dynamic propagation and arrest of buckles in pipe-in-pipe systems

Abstract

Experiments and large scale numerical simulations are used to study the dynamics and the arrest of propagating buckles in pipe-in-pipe systems. In the first set of experiments the velocity of buckles initiated in a constant pressure environment is measured as a function of pressure using first water and then air as pressurizing media. For the outer and inner pipe parameters used, the buckle velocities correlated well with values measured in single pipes. The dynamic propagation experiments in air were then simulated numerically. Calculated buckle velocities followed the same trend as the measured values although they were somewhat higher. In the second set of experiments the effectiveness of internal ring buckle arrestors designed with previously developed quasi-static design procedures is re-evaluated under dynamic buckle propagation. In all cases examined the dynamic arresting efficiency was found to be higher than the quasi-static one. The same behavior was also observed in corresponding numerical simulations. This indicates that design of such devices using quasi-static design criteria should be conservative.