Effect of axial length parameters of ovality on the collapse pressure of offshore pipelines

Axial length parameters of ovality are observed to have effects on the buckling capacity of a pipeline through a parameter analysis. The collapse pressure measured was considerably higher than that calculated by offshore standard DNV-OS-F101 (DNV) when the axial length of ovality was shorter. Effects of composite defects in the form of corrosion ovality on collapse pressure were examined through combined experimental and numerical efforts. We find that the final collapsed configuration and buckling capacity of a pipe are not only affected by the amplitude of maximum ovality and geometric parameters of corrosion but also by their positions. Finally, an improved formula and procedure for estimating the collapse pressure of a pipe with composite defects is established.