The effect of general and localized corrosions on the collapse pressure of subsea pipelines

Abstract

The objective of this work is to estimate the collapse pressure of steel pipelines subjected to random non-uniform general corrosion and localized corrosion. Non-linear, large deformation and three-dimensional finite element analyses are employed to assess the reduction in collapse pressure of the offshore pipelines under external pressure. The numerical approach is validated against published experimental results of corroded pipe specimens. Finite element models with various levels of corrosion deterioration on the surface of pipelines are taken into consideration. General corrosion with a non-uniform thickness reduction with a mean value of 10% results in a 10–13% loss in the collapse strength of the corroded pipe. In another case of general corrosion with a mean value of 40% thickness reduction, there is a 45% reduction in the collapse strength of the pipe, which shows the necessity of considering the general corrosion in the evaluation of the residual strength of subsea pipelines. It is concluded that ovality plays an important role in the strength evaluation, whereas the effect of the eccentricity is insignificant. It is also shown that different collapse modes are induced in the pipe models with various locations of the corrosion.