Utilizing In-Line Inspection Data and Structural Reliability Analysis to Set a Defendable Corrosion Re-Assessment Interval

A quantitative pipeline integrity analysis based on structural-reliability methods has been used to establish corrosion re-assessment intervals from in-line inspection data. This process, as implemented in a simulation-based software package, incorporates in line inspection (ILI) data, physical and operation characteristics of the pipeline, corrosion growth rate projections, and the uncertainties inherent in this information, to estimate the probability of failure (POF) as a function of time. Using this approach, the POF value is calculated on a joint-by-joint basis and the calculated values are then compared with an acceptable POF level to verify the integrity of each joint in any given year. Based on this information a re-assessment interval is established and selected joints are targeted for excavation and repair to ensure that the acceptable POF level is not exceeded.