Pipe Spring System: The MFL Identification, Characterization, and Assessment of Both Defects and Sleeve

Abstract A full encirclement laminated steel sleeve system has been designed, developed, tested, vetted by the industry, and utilized on North American regulated pipelines for permanent repairs of pipeline integrity threats. Pipeline integrity practitioners requested verification of various aspects of MFL based ILI inspections. This paper briefly reviews the details of the technology regarding the material, the mechanics and mitigation principles, and the field installation of the thin layer laminated steel sleeve system. We then address the MFL based ILI inspection topics. Three major topics have been investigated. These are: Verification that MFL based ILI can readily identify the volumetric metal which comprises the laminated steel sleeves system. Sleeves which were comprised of 2,4 and 8 layers of steel were temporarily installed on a pipeline system prior to a scheduled ILI run. The ILI provider was not informed prior to data collection. The pipeline operator maintains the in-house ability to quickly review vendor ILI data and provided initial assessment and analysis. This data has been collected the results are presented. Determination of the ability of MFL ILI based inspection to assess metal loss defects which have been permanently repaired with this technology. An ILI service provider created a series of various known calibration type defects and collected initial pull test data on unrepaired spool pieces. These defects were then repaired with the thin layer laminated steel sleeve system. The change in magnetic response between unrepaired and repaired runs has been evaluated for the various calibration type defects. The targeted goal of the effort is to build the algorithm or model to assess known defects after repair and installation of this sleeve system. These results are presented and discussed. Determination of the ability of MFL based ILI to inspect or verify that the magnetic response or magnetic signature of the laminated steel sleeve system can be assessed with sufficient consistency to indicate that that the sleeve displays no significant changes during service. This would provide confidence that the sleeve continues to effectively perform its intended mitigation. The results are presented and discussed.