Integral buckle arrestors for offshore pipelines: Enhanced design criteria

Integral buckle arrestors are relatively thick wall rings periodically welded in an offshore pipeline at intervals of several hundred meters in order to safeguard the line in case a propagating buckle initiates. They provide additional circumferential rigidity and thus impede downstream propagation of collapse, limiting the damage to the length of pipe separating the two arrestors. The effectiveness of such devices was studied parametrically through experiments and numerical simulations in Park and Kyriakides [On the design of integral buckle arrestors for offshore pipelines. International Journal of Mechanical Sciences 1997;39(6):643–69]. The experiments involved quasi-static propagation of collapse towards an arrestor, engagement of the arrestor, temporary arrest, and the eventual crossing of collapse to the downstream pipe at a higher pressure. The same processes were simulated with finite element models that included finite deformation plasticity and contact. The experimental crossover pressures enriched with numerically generated values were used to develop an empirical design formula for the arresting efficiency of such devices. A recent experimental extension of this work revealed that for some combinations of arrestor and pipe yield stresses, the design formula was overly conservative. Motivated by this finding, a new broader parametric study of the problem was undertaken, which demonstrated that the difference between the pipe and the arrestor yield stress affects significantly the arrestor performance. The original arrestor design formula was then modified to include the new experimental and numerical results producing an expression with a much wider applicability.