Inspection strategy for optimizing subsea pipeline integrity management
Proceedings Publication Date
Dr. Manuelle Corbani Romero
Manuelle Corbani Romero, Rafael Wagner Florencio dos Santos, Pedro Addor
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Petrobras currently operates over 4.000 kilometers of subsea rigid pipelines across Brazilian waters. To ensure safe transportation of hydrocarbons, the integrity management (IM) plan of pipelines involves periodic inspections. However, inspection of subsea pipelines is a challenging task. Not only are the pipelines manufactured with insulating layers which hinder external inspection, but also flaws can be found randomly distributed along the entire length. Intelligent pigs have been used as the preferred inspection method, but approximately 50% of the global pipeline network are not fitted for in-line inspection due to several factors, including multi-diameters design, tight bends, and Y-connections. Modifying pipelines to include pig’ launcher/receiver is often not cost-effective. This paper presents Petrobras’ inspection strategy to enhance IM of both, piggable and unpiggable pipelines. Two categories of inspection tools, i.e. screening and localized, are under qualification to operate in 2000 m water depths. Screening tools are designed to inspect the entire length at at least a 1 m/s rate, locating the defects. Then, localized tools are sent to those locations, to quantitively characterize the defect, allowing precise fitness for service analysis to be ran. The screening strategy for piggable pipelines is to add DMR (Direct Magnetic Resonance) technology to low-cost cleaning pigs frequently run. If no defect is identified, intelligent pig run can be postponed. Unpigabble pipelines require a different approach. ROV deployed tools externally inspect through the insulating layers. MMM (Metal Magnetic Memory) technology can be used for screening. Localized tools are split into two categories depending on the type of defect, corrosion defects or cracks. Qualified localized tools use Acoustic Resonance Technology (ART) and ultrasonic techniques, such as Phased Array and TOFD. These tools can also be deployed in piggable pipelines to improve accuracy of flaw characterization by cross-checking results with pig data.

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