Under special circumstances a fast propagating crack can be triggered in pipelines by just a small local damage. In order to assess the safety with regard to this type of catastrophic failure, an analytical model was established to describe the process of large ductile tearing mathematically. Using a simplifying kinematical model and the hypothesis that the tearing fracture process is governed by a constant CTOA, the total energy dissipation rate can be quantified and compared to the available fracture energy. Since the Charpy fracture energy KV is often the only available toughness-related material parameter of existing pipelines, the toughness parameters used in the model, particularly CTOA, has to be determined from KV. This was achieved by using the same 2-parameter model of ductile tearing to analyse the fracture process in bending. A closed form relationship was obtained between the minimum pressure required for fast ductile crack propagation and the system and material parameters. It could be shown that rapid ductile tearing requires the hoop stress to exceed a certain limit, which depends on the geometrical parameters of the pipeline and KV of its material. The analysis was verified by comparison of the results with the experimental data of full-scale burst tests available in the literature. Unlike empirical correlations, the derived analytical formula seems to be universally valid, regardless of pipe dimensions or steel grades.

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