Innovation under pressure
Published by Alfred Hamer,
Editorial Assistant
World Pipelines,
Niels Pörtzgen and Gerard van der Steen, Applus+, Netherlands, outline the evolution of pipeline girth weld inspection.
In the dynamic world of oil and gas, where operational efficiency and safety must go hand in hand, the integrity of pipeline infrastructure is critical. As pipelines serve as the arteries of energy distribution across vast distances and terrains, their constant exposure to extreme environments makes maintenance and repairs a top priority. Over time, pipelines naturally degrade, sometimes under the pressure of water for pipelines installed on the seabed. When damage to such pipelines is observed, a repair system is required that can be used under submerged conditions. Likewise, an inspection strategy under the same conditions is needed to ascertain the adequate repair of the pipeline.
A hallmark of technological advancement in the energy sector is the Pipeline Repair System (PRS), developed by Equinor and Applus+, which is designed specifically for subsea pipeline welding for repairs but also for tie-ins of pipeline extensions. The PRS consists of several pieces of equipment that can be deployed on the seabed for operations like cutting, bevel preparation, and positioning of pipe ends, as well as welding and weld inspection. As part of the PRS system, a novel technology for ultrasonic inspection, the IWEX system, has recently been validated and used to verify the integrity of the girth weld with high reliability and precision.
This article will explore the challenges of pipeline repair and tie-in operations under deep submerged conditions on the ocean or sea floor. Furthermore, requirements resulting from these challenges, as well as from client specifications and industrial standards, will be discussed. We will present and illustrate how the IWEX system has met these requirements.
Operational conditions on the seafloor
When pipelines installed on the seafloor are damaged and require a repair, in principle, the damaged section must be removed, and a new section must be installed. Economically, the operation is usually more attractive than installing a new pipeline. However, since the line has already been installed on the seafloor, it is typically not practical to lift the pipe for repair operations. Consequently, this must be done on the seafloor. The same scenario applies to existing pipelines that require an extension, whereby a tie-in weld connects the existing line with a new section.
Pipeline operations under submerged conditions are obviously more challenging than on land. Any technology applied should be water-resistant, or alternatively, a water-free room must be created, such as a diver’s bell, i.e. a habitat, in which the technology can be used. Not only does the water itself introduce a challenge, but at deep depths, the pressure due to the water will also be very high. Therefore, the technology should be able to perform under high pressure, i.e. hyperbaric conditions.
Typically, technology requires a power supply and communication lines. Such lines should be long and robust enough to secure reliable performance and avoid data loss. Moreover, the technology may require separate parts or tools, which must be supplied to the location below.
In cases where the technology can only be controlled by humans, a diver is required to wear a special suit and breathing gear, which may consist out of a mixture of breathing gases. A diver will have a limited time window to perform activities, which will also introduce a challenge. Furthermore, due to the bulky divers’ suit, the technology should be easy to handle without the need for refined manipulations.
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Read the article online at: https://www.worldpipelines.com/special-reports/20012025/innovation-under-pressure/
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