Industry players are exploring ways of transporting hydrogen as an additive or replacement for natural gas, but currently, offshore pipeline codes insufficiently cover the transport of hydrogen or hydrogen blends by offshore pipelines. The DNV standard for submarine pipeline systems (DNV-ST-F101) includes hydrogen as a listed transport product, but additional considerations are required to meet the target safety level for an increased use of hydrogen. A special concern in this respect is the potential detrimental influence of hydrogen on resistance to cracking in carbon steels. To support the uptake of hydrogen as an energy carrier, it is imperative to update the standard, to reach design and material requirements that do not compromise pipeline integrity and safety.
To address these challenges, DNV started the first phase of H2Pipe in 2021: an initial test program looking into potential degradation of steel pipe mechanical properties was carried out to fill gaps in existing knowledge and to explore various test parameters as a preparation and narrow down the number of variables for the main test program planned for Phase 2. The first revision of the guideline was delivered to participants the same year. The guideline is currently at a high level, and more work is needed to develop more specific acceptance criteria.
Phase 2 of H2Pipe is planned to start in Q1 2023 and last 2 years. It will consist of a comprehensive experimental test program to enhance the understanding of the governing hydrogen embrittlement mechanisms and how hydrogen affects the integrity of the line pipe material. In addition to the experimental test campaign, Phase 2 will also include tasks such as a feasibility level design of offshore hydrogen pipelines and a risk assessment study to look at safety aspects of offshore hydrogen pipelines. The primary outcome of Phase 2 of the JIP is expected to be a detailed guideline offering specific guidance for use in design and re-purposing of offshore pipelines for hydrogen transport.
“The results from this JIP will allow us and our partners to further develop the guideline to a level where it can offer direct and detailed support in the design and re-qualification of offshore hydrogen pipelines,” said Jan Fredrik Helgaker, Senior Engineer and JIP Lead, Energy Systems at DNV. “With real design limitations, industry players will be able to design – or repurpose – pipeline systems fit for the safe transportation of hydrogen, and to implement adequate mitigation measures if necessary.”
