Detecting, characterizing, and assessing mechanical damage (MD) to operating energy pipeline systems is an important component of an operator’s Integrity Management Plan (IMP). In the process of selecting ILI technologies that are best suited for detecting and sizing the types of mechanical damage (MD) that may pose integrity concerns, it is critical to understand the capabilities of current ILI technology. Data and information provided by participating ILI vendors, in conjunction with the extensive volume of previous work and studies on ILI tools and techniques, provided the basis for determining the capabilities and deficiencies of the current MD ILI technologies, and for validating performance claims. The performance measures evaluated were dent depth sizing accuracy, probability of detection, and sizing tolerance for gouge and metal loss within dents.
The methods and procedures specified in API 1163, namely, Binomial Distribution Analysis, Binomial Confidence Interval Analysis and Least Square Linear Regression Analysis, were used for the analysis and evaluation. The capabilities of current technologies were evaluated in terms of their sizing and probabilities of detection, identification and false call (POD, POI and POFC) based on the available data. Most of the plain dents that require repair or evaluation by the current PHMSA/OPS Integrity Rules can be detected and sized by commercially available ILI tools specialized to detect either deformation or metal loss. Mechanically induced gouges without dents can also be reliably detected and sized by some of the MFL tools.