Safety and Integrity of Hydrogen Transport Pipelines

Rørledningsnettverket på havbunnen av den norske kontinentalsokkelen (NCS) blir i økende grad anerkjent som en mulighet for storskala transport av hydrogen fra Norge til Europa. Bruk av eksisterende naturgassrørledninger til transport av hydrogengass medfører flere utfordringer, spesielt risikoen for hydrogensprøhet. For å ivareta sikkerheten ved hydrogentransport er det viktig å forstå hvordan hydrogenet påvirker rørledningsmaterialene. Nyere resultater fra RCN-prosjektet HyLINE (2019-2023) viser at selv om hydrogen påvirker de mekaniske egenskapene til undersøkte rørledningsstål negativt, kan de fortsatt oppfylle eksisterende designstandarder. Den varmepåvirkede sonen i sveisene ser imidlertid ut til å være mer sårbar. For å håndtere dette problemet vil HyLINE II spesifikt fokusere på materialintegriteten i sveiseforbindelser i undervannsrørledningene og undersøke hvordan de påvirker rørledningens integritet. Tre doktorgradsstipendiater og en forsker skal jobbe i prosjektet. Forskningspartnere SINTEF, NTNU og Kyushu University (Japan), vil samarbeide med nasjonale og internasjonale industripartnere som omfatter hele verdikjeden for hydrogenøkonomien. Disse partnerne inkluderer Equinor, Gassco, Total E&P, TechnipFMC, Tenaris Dalmine og AS Norske Shell.

The subsea pipeline network on the Norwegian Continental Shelf is gaining traction as an opportunity for large scale transport of hydrogen from Norway to Europe, supporting a long-term and sustainable development of the energy system and contributing to the transition to a zero-emission society. The safety and integrity of the pipelines exposed to internal pressurized hydrogen gas must however be ensured. Pipeline steel welded joints are generally of higher strength than the adjacent base metal, featuring complex microstructures, potential flaws and residual stresses which in sum renders them more susceptible to being embrittled by hydrogen, so called hydrogen embrittlement. The existing Norwegian pipeline infrastructure consists of approximately 740,000 girth welded joints, all requiring special attention to ensure structural integrity in a hydrogen gas environment. HyLINE II will therefore address the follow key research questions: •How different microstructures, surface oxides and charging conditions affect uptake, diffusion and trapping of hydrogen globally and locally in the welded area? •How hydrogen influence the local mechanical properties of microstructures in the HAZ and what are the critical local damage and fracture mechanisms? •What is the susceptibility of hydrogen induced fracture in welded joints under static and cyclic loading in hydrogen conditions? •How to best represent and simulate hydrogen diffusion and trapping and the interplay between hydrogen, material and mechanical response on a local and global scale using numerical tools for fracture assessment? The project consortium includes the pipeline operator Gassco, the energy companies Equinor, Total E&P and Norske Shell and the technology provider Technip FMC. The research will be performed by SINTEF, NTNU and Kyushu University (JP) in collaboration with Imperial College (UK), Fukuoka University (JP) and Max Planck Institute for Iron Research (GER).