Demonstrating in-line inspection (ILI) to monitor cracks assuring compatibility for operation with hydrogen in new and re-purposed offshore natural gas pipelines

Expected Outcome:Current existing natural gas grids are expected to form a substantial part of the future hydrogen transport and distribution system. Current industry initiatives such as the European Hydrogen Backbone Initiative of major TSOs and Ready4H2[1] of the European DSOs is showcasing how this could progress.While the work to assure the integrity of the pipelines and components in the grid have progressed in previous projects and activities, the main focus has been on onshore infrastructure. Offshore pipelines have specific design rules and different operating conditions and cannot be excavated for maintenance or service purposes in the same manner as onshore pipes. This means that existing infrastructure should maintain longer, without service or exchange of segments. The consequences of fatigue and cracks could endanger the complete business case of the pipeline. Similarly, it is very expensive to retrieve inspections tools if they get stuck and this situation should be avoided by design and by the way of operating and handling the tool. Also, the offshore pipelines have a larger diameter and are operated under higher pressure. Although, it is in the common interest of both onshore and offshore transport grid operators to have In-line Inspection tools that can operate in hydrogen pipelines, higher standards apply for the offshore use case. It has been observed that the most critical points in offshore pipeline integrity are the circumferential welds and seam welds. Therefore, their accurate detection is a key factor in advancing research on the repurposing of gas pipelines for hydrogen transport. The integrity of offshore pipelines for hydrogen transport cannot currently be guaranteed due to hydrogen's detrimental effect on fracture toughness, ductility as well as the increase of fatigue crack growth rate, especially in regard to stress concentration areas and required performance of ILI-tools are not fully established.The project results are expected to c