RELIABILITY-BASED EVALUATION OF PIPELINES USING ABOVE GROUND INSPECTION METHODS FOR EXTERNAL CORROSION

摘要

Above ground inspection methods such as Close Interval, AC Current Attenuation, Direct Voltage Gradient and Pearson surveys are often employed to examine pipelines for external corrosion, especially when in-line inspection and hydrotesting are not feasible. Compared to in-line inspection, these methods can be superior in identifying general areas of corrosion, however, they generally have a higher probability of missing significant defects. This paper examines the use of quantitative reliability-based methods for assessing the integrity of pipelines that have been inspected using above ground methods where these inspections are followed up by a selective excavation and defect sizing process. Special consideration is given to the inference of the size distribution of undetected defects when the number of detected defects is small.