In most circumstances, a customer request for a 14” pipeline inspection over 15 kilometers which meets ROSEN’s high-resolution MFL specifications is one that is executed successfully countless times. In this case, however, there were multiple unique challenges to overcome, including:
- Heavy black powder deposits
- Low pressures of approximately 15 bar
- First-time inspection resulting in many unknowns
Black powder is a solid deposit found in gas pipelines which becomes present through a variety of sources, including mill scale from the pipe manufacturing process, internal pipeline corrosion, or even directly from gas gathering systems. Without the much needed pre-inspection cleaning, the low-pressure inspection technology could not be properly applied. The operator’s goal was to complete a corrosion survey that met all government regulations.
Initial cleaning runs indicated the line was clean enough to commence the geometry service, which includes technology based on eddy current combined with a specially modified low-pressure kit. Although the geometry inspection went well, the tool was retrieved showing still a significant amount of debris present in the line, and therefore a more vigorous cleaning approach was needed.
A customized heavy-duty cleaning tool was devised using the ROSEN Toolbox method. The tool was adapted from an MFL-based system, fitted with fewer magnets than a typical tool, and descaling cups were added to combat the low-pressure operating conditions. Hereby creating a completely tailored system from existing components, which functioned as expected.
Following the successful cleaning campaign using this specialized tool, the on-site team was convinced the metal loss inspection could take place with a low-friction MFL-based technology. In the case of low-pressure pipelines, a dominant challenge is to overcome speed excursions which normally occur during inspection runs as a result of passing bends, wall thickness variances, welds, or the presence of debris. In this case, the MFL-based system was optimized for these conditions by utilizing the following elements:
- Low-friction wheeled magnetizer yokes
- Enhanced cup design for reduced and constant friction
- Customized yoke support system
- Friction reducing odometer unit
- Ultra-compact and light weight design
The tailored approach allowed for optimized adaptations in regards to cleaning and inspecting the pipeline. In addition, the solution was completed during regular operation with no loss in production or impact on operations.
Compliance & Safety
Complete data sets allowed for a full assessment of the pipeline condition, and played a vital role in the pipeline integrity management plan. This ensures compliance with safety standards and regulations.