Ductile Fracture Propagation and Arrest in Offshore Pipelines

The problem of ductile fracture propagation in pipelines, already extensively studied in the past in the case of buried pipelines, has been receiving the close attentions of research institutes and companies in the last decade or so for offshore pipelines too; the aim is to allow a correct choice of toughness levels of the steels employed for such applications. The first studies in the field consisted essentially in model tests; more recently full-scale tests were performed, while at the same time the first attempts were made to interpret and model marine backfill. As a result the main effects of marine backfill on ductile propagation were put into evidence and quantified. In particular, because of the overpressure field generated around the pipe subsequently to fracture initiation, the marine backfill comes out to be more effective than soil in arresting a running fracture, and consequently very low toughness levels are required for offshore pipelines.