Abstract
An internal corrosion (IC) threat assessment was performed on a transmission gas pipeline by conducting a thorough analysis of operational and historical data in early 2011. The outcome of this assessment was compared with the results of the pipeline integrity assessment conducted using an in-line-inspection (ILI) tool, later that year. The objective of this study was to evaluate the accuracy of the internal corrosion threat assessment when compared to actual data from an integrity assessment.
The IC threat assessment based on analysis of gas quality, failure history and pigging samples indicated minimal threat of internal corrosion in the pipeline. The ILI data confirmed this IC threat assessment results having no internal metal loss features. The wall thickness measurements made during anomaly investigations also indicated lack of metal loss and hence no internal corrosion.
A thorough analysis of operational and historical data can be used to accurately assess the threat of IC in dry gas pipelines. This approach is useful in assessing transmission pipelines for IC threat in between scheduled integrity assessments. It can also be used to assess the IC threat in un-piggable dry gas pipelines. It is important to compare and confirm IC threat assessment results with in-the-ditch data and inspections during direct assessment and other projects.
