Abstract
This study collected and analyzed field data to validate the probabilistic model developed previously for predicting internal corrosion threats resulting from condensed water from nominally dry natural gas. Model-predicted wall loss was compared to actual measurement to validate the model. One past failure case from the National Transportation Safety Board(1) due to internal corrosion and in-line inspection (ILI) data from five pipeline operators were collected and used to validate the Model. Two of the data sets indicate wall loss that is either evenly distributed at all locations around the circumference of the pipe or predominantly at the top of the pipe, which is in agreement with the negligible wall loss predicted by the Model. Another two sets of data show significant wall loss occurring at the bottom of the pipe, which is in agreement with non-negligible risk of internal corrosion predicted by the Model. The 5th data set confirmed the analysis of ILI data uncertainty and corroborated the validation results. For the failure case, the prediction is in good agreement with the post-failure examination. Although uncertainties exist in both Model predictions and ILI measurements, the wall loss predictions from the Model are in good agreement with trends seen in the ILI measurements.
