Underwater burst tests for evaluating unstable ductile crack arrestability in offshore pipelines

We conducted a series of short pipe burst tests with and without water backfill to investigate the difference in crack arrestability between offshore and onshore pipelines. The results clearly showed that the crack arrest lengths in underwater pipes were shorter than those of pipes with no backfill. Although underwater pipes have characteristics that both enhance and suppress crack arrestability, the effects of arrest-enhancing factors are considerably greater in water as shallow as 2.0 m. Analytical results using the HLP method show that the effect of the surrounding water is equivalent to making the material 1.6-2.8 times tougher.