Pipelines can show imperfections at the longitudinal weld. These imperfections are often introduced by the welding process in the pipe mill and can differ from mill to mill and welding technology. Some of those imperfections are acceptable variations within the manufacturing specifications of the longitudinal seam, either on the internal or external weld trim or cap. Others may exceed acceptable tolerances and introduce a risk for safe operation. In addition, sometimes radial offsets, misalignment, peaking and flat spots can occur. All those variations can lead to signals wrongly classified as crack-like defects, leading to unnecessary repair activities or shading of real flaws. A phased array based ILI tool can map and accurately measure localized wall thicknesses and surface variations. Phased array elements typically have a width of 0.4 mm (16 mils) to 0.8 mm (32 mils), which enables high circumferential resolution compared to the latest generation of traditional single sensor ultrasonic tools of 2 mm (79 mils), while the ILI industry standard has a circumferential resolution around 4 mm (158 mils). This increase in resolution can be used to reconstruct the inner surface, the wall thickness and outer surface of the long seam itself and the vicinity. This includes misalignment, the weld cap height and width, potential trim issues, and similar effects. The authors will show and explain the robustness of the measurement methodology based on laboratory/test data and real-world pipeline inspection. Furthermore, the benefit of knowing accurately the local seam wall thickness will be discussed, as a higher wall thickness reduces the severity of defects. For a selected set of anomalies, it can be shown that a significant number that may exceed acceptable limits (actionable anomalies) can be treated as non-critical considering the ILI measured local WT. Finally, the authors show how the gathered data can be used to build 3D models and perform simulations with different flaws to further optimize the inspection tool and utilize the phased array tool to its maximum benefit.
Ultrasonic crack inspection services have become a standard solution for pipeline integrity programs, especially for liquid pipelines. ILI tools provide reliable and accurate data for assessment of axial and circumferential cracking defects to derive educated decisions on the integrity and maintenance of the asset. This technology inspects common media such as crude and light oils, water, diesel, benzene, or similar. Running tools in mediums used for commercial operations does not affect the throughput of the line. Crude and light oils, water, diesel, benzene etc. have relatively constant ultrasonic characteristics with varying pressures and temperatures and are very suitable for ultrasonic inspections, therefore called common media within the context of this paper. If the medium in the pipeline does not fall within the common media, the situation changes. These media are called challenges media. Especially for liquefied natural gases (LNG) or liquefied petroleum gases (LPG) where temperature and pressure have a significant impact on the ultrasonic characteristics of speed of sound, density, and attenuation. LNGs and LPGs typically contain high amounts of propane, butane, and some other higher order alkanes. Due to the high variability of these components to external boundary conditions, inline inspections in these type of pipelines are usually performed by replacing the medium with a more feasible one, e.g. water or diesel. This causes significant impact to productivity and throughput and increases costs and efforts. The authors will present the work performed to overcome and solve this workaround and run an ultrasonic crack inspection tool in LNG. This paper highlights the challenging aspects considered to successfully perform inline inspections in LNGs. We will present a standardized and systematic approach to overcome limitations of the technology in such media. Starting with the challenges and ideas for enhancement of the service, the paper will discuss the design of the experiment, the experiment itself, the results, and present the conclusions that resulted in the tool development and the analysis procedure. Finally, the authors will present the application of the enhanced service in a customer pipeline, including ILI preparation, execution, analysis, and in-the-ditch verifications. The structured and systematic approach allows the inspection company to perform successful and reliable crack detection inspections in LNG lines. This includes axial and circumferential cracking threats.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.