The inspection of the vertical section of an offshore pipeline, known as the riser, plays a critical part of any integrity management program. This section connects the pipe that runs on the seabed to the production facility, be it a floating platform or a FPSO. Hanging from the platform over deep waters, risers are subject to very extreme operating conditions such as high loads and underwater currents. Corrosion, fatigue, abrasion and damages caused by stray object collisions are factors that must be taken into account, so that oil and gas production are not compromised. A flexible pipeline, a well engineered solution used in most riser installations, provides high reliability while requiring little maintenance but, in spite of advances in project and installation, the inspection of riser pipelines is an immature field where technology has not yet met the user’s demands. In the search for better riser inspection techniques, a project was started to design a new inspection tool. The basic concept consists of an autonomous vehicle, the Autonomous Underwater Riser Inspection tool (AURI), that uses the riser itself for guidance. The AURI tool can control its own velocity and is suited to carry different types of inspection devices. The first AURI prototype is designed to perform visual inspection with an built-in camera system, covering 100% of the external riser surface. The AURI can reach water depths up to a thousand meters. It was built with several embedded security mechanisms to ensure tool recovery in case of failure and also to minimize chances of damage to the pipeline or other equipment. It uses two electrical thrusters to push it along the riser. The mission is set to a maximum depth to be inspected and is considered complete when one of the following conditions is met: (1) maximum pressure on depth sensor is reached or (2) the length of the run is achieved or (3) maximum mission duration is exceeded or (4) maximum allowed tilt is detected by the inclinometer. Thanks to its positive buoyancy, the AURI will always return to the surface even if the electronics fail or the batteries get exhausted. This paper presents the first AURI prototype as well as the preliminary test results.
- International Petroleum Technology Institute and the Pipeline Division
Autonomous Underwater Riser Inspection Tool
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Camerini, C, Freitas, M, Langer, RA, von der Weid, JP, & Marnet, R. "Autonomous Underwater Riser Inspection Tool." Proceedings of the 2010 8th International Pipeline Conference. 2010 8th International Pipeline Conference, Volume 3. Calgary, Alberta, Canada. September 27–October 1, 2010. pp. 673-679. ASME. https://doi.org/10.1115/IPC2010-31485
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