PR-244-093703-R01 Uncertainties of In-line Inspection Crack Detection Tools Phases 1-2

This project was carried� to develop better approaches to deal with in line crack inspection tool uncertainty. The primary objectives of the project were as follows: To develop practical and defendable methodologies to quantify the de facto tool accuracy for a specific pipeline, taking into account the limitations associated with field excavation programs.� To develop methodologies that can be used to incorporate the above mentioned tool characterizations into the crack management process. The objectives were addressed in two parts: first by estimating the number of defects in the pipeline, and second by estimating the reliability of the pipeline given the defect count and size distributions. Sections 2 and 3 of this report detail the models used to estimate the number and size of defects in the pipeline. Section 4 details the reliability models used as a basis for crack management. API Standard 1163 titled �In line Inspection System Qualification Standards� provides performance based requirements for in line inspection (ILI) systems, including procedures, personnel and equipment. The standard provides a starting point and terminology for discussions on in line tool performance and is referred to throughout this report. In line tool accuracy is defined in API 1163 in terms of probability of detection (POD), probability of identification (POI), probability of false call (POFC) and sizing accuracy. Models for each of these performance measures is developed and exercised using four operator ILI and excavation data sets for stress corrosion cracking (SCC) defects. The model results are then applied to a crack management process that utilizes pipeline reliability as a basis for decision making. An overview of the models developed for POD, POI, POFC and sizing, as well as key results from the crack management process, is presented.