Abstract
Corrosion assessment is essential for future pipeline integrity and for planning safe and cost effective rehabilitation strategies. The application of deterministic corrosion growth assessment procedures to prediction of fitness for purpose (FFP) requires the use of data that are often subject to uncertainty. The use of upper bound or extreme values for the relevant parameters such as the upper bound of a reported corrosion size or the maximum corrosion growth rate can lead, in some circumstances, over-conservative predictions of pipeline integrity. An alternative approach is to use statistically based structural reliability methods to allow for the uncertainties in the parameters and to assess the probability of failure of pipelines containing flaws. This paper describes a systematic approach that incorporates statistical analysis with mechanistic understanding of corrosion to minimize uncertainty in determining representative corrosion growth rate and to quantify probability of failure along the pipeline. The methodologies include Decision Tree Analysis and Probability of Exceedance (POE). Application of methodologies and comparison with deterministic approaches for future integrity assessment are discussed.
