The pipeline industry is moving toward the implementation of reliability-based integrity management approaches, which account explicitly for the uncertainties associated with ILI data, material properties, and failure pressure modeling. The uncertainty associated with defect sizing has been shown to have a significant impact on reliability estimates and consequently the number of features requiring remediation, the re-inspection interval/frequency, and the number of digs needed to confirm the ILI tool performance.
While some guidance is available to assist operators in accounting for in-ditch sizing error in the context of verifying whether or not ILI tool performance is consistent with vendor claims (e.g. API 1163 – Appendix E), no explicit guidance is currently available to assist operators in accounting for in-ditch sizing error when field dig data is to be used to update the claimed measurement error. The aim of this project is to address this deficiency by accomplishing the following objectives:
The scope of this research was limited to external corrosion metal loss dimensions, specifically depth and length. Follow-on research (EC-4-3 & EC-4-5) will focus on assessing ILI tools’ sizing tolerances, understanding the relationship between the measurement error and the resultant predicted and actual burst pressures, and developing ways to work with the error.