Probabilistic estimation of remaining life of a pipeline in the presence of active corrosion defects

A methodology is presented for the assessment of remaining life of a pressurised pipeline containing active corrosion defects. A probabilistic approach is adopted to this methodology and the associated variables are represented by normal or non-normal probabilistic distributions. A failure pressure model based on fracture mechanics is adopted for the assessment of pipeline failure pressure and linear idealisation of the long-term corrosion growth rate is carried out. Because of the presence of nonlinearity in the limit state function and also of the presence of non-normal variables, the Level II advanced first order second moment iterative method is employed for carrying out reliability analyses. The methodology is applied to an example pipeline and the remaining useful life of this pipeline is assessed. Relative contribution of the random variables and the sensitivity of the reliability index to the change in variance of the random variables is also investigated.