Comparison of Numerical Results and Design Criteria for Buckle Propagation and Buckle Arrestor Design

Buckle propagation is a relevant design criterion for deep-water offshore pipelines. Imposed by external impact or local bending, e.g. during laying, a local buckle can be initiated, thereby decreasing the collapse strength of the pipeline. As a result of the high ambient external pressure, the buckle can start to propagate. Several design criteria for buckle propagation exist. This paper compares different design criteria with numerical results to obtain an impression of the levels of conservatism applied in the various codes. In most design cases, it is not suitable to avoid buckle propagation by using an increased wall thickness over the entire pipeline. Therefore, buckle arrestors are installed to stop the propagation. The common technical solution is to install sections of thicker pipeline, which requires that the buckle arrestor wall thickness and the length of the buckle arrestor have to be determined during design. A distinction is drawn between short and long buckle arrestors. Both cases are considered here. The design of the buckle arrestor can be carried out by using well-known criteria, such as the criteria developed by Kyriakides, Langner or Torselletti et al. These criteria are compared with experimental data. Numerical calculations are carried out and the results are compared with the design criteria.