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Zur Umsetzung der wasserstoffbasierten Energiewende ist eine zuverlässige Transportinfrastruktur unverzichtbar. Hierfür ist die Nutzung großer Teile des vorhandenen Erdgasnetzes vorgesehen. Im Rahmen von Reparatur- und Wartungsarbeiten ist das Schweißen im Betrieb an Erdgaspipelines Stand der Technik. In Verbindung mit Wasserstoff wirft diese Technik jedoch Fragen der Materialverträglichkeit auf. Das im Vortrag vorgestellte Projekt H2SuD leistet Beiträge zur Aufklärung des Einflusses von Reparaturschweißprozessen auf die Wasserstoffaufnahme und Degradation im Betrieb befindlicher H2 Gasleitungen. Ein Schwerpunkt des Vortrages liegt auf der im Projekt erarbeiteten Prüfmethode für Modellversuche, mit denen der Einfluss von Schweißen im Betrieb an Pipelines auf die Wasserstoffaufnahme getestet wird. Die Durchführung erster Versuche und dabei erzielte Ergebnisse werden präsentiert.
As energy carrier of the future, green hydrogen can make a decisive contribution to a sustainable energy supply. In Europe concrete plans for a hydrogen pipeline grid already exist, as the so called “European Hydrogen backbone”. As building a completely new pipeline grid is economically not justifiable, a dual-way strategy of repurposing natural gas (NG) pipelines and newly built pipelines is intended. Long distance pipeline grids require regular maintenance and repairs. In that conection, for natural gas (NG) pipelines in-service welding is state of the art. Concepts such as hot-tapping (drilling into pressurized pipelines) and “stoppling” (sealing off pipeline sections after installing bypasses or pressure relieves) allow the repair of damaged pipeline sections or the installation of new branches without shutting the pipeline down. The EIGA 121/14 guideline already pointed out in 2014 that “a hydrogen hot-tap shall not be considered a routine procedure”. This shows that the determination of the transferability of these repair concepts to hydrogen pipelines is of utmost importance. Due to the degrading effects of hydrogen on mechanical proper-ties, commonly referred to as “hydrogen embrittlement” it is necessary to understand and investigate the occurring effects. In the special case of repair welding on in-service hydrogen pipelines an increased hydro-gen uptake due to a large heat input and microstructural changes in the material needs to be considered. For this reason, this paper gives an overview on existing weld repair concepts and its risks and limitations in terms of hydrogen absorption and possible embrittlement effects when transferred to hydrogen pipelines. The complexity lies in a large variety of materials (low alloyed steels), pipeline diameters and corresponding welded joints. The material compatibility of materials in used (repurposed NG-pipelines) and new condition must be investigated. Particularly for repurposed/used pipelines the effect of a pre-matured/corroded inner surface and sometimes insufficient documentation of the material “history” needs to be considered. An overview on ongoing and completed R&D-projects with respect to repair concepts for hydrogen pipelines and hydrogen effects on pipeline materials is given.
As energy carrier of the future, green hydrogen can make a decisive contribution to a sustainable energy supply. Particularly important is the decarbonization of heavy industry. Therefore, a reliable supply of hydrogen must be guaranteed. A hydrogen pipeline grid can achieve this purpose. In Europe concrete plans for a hydrogen pipeline grid already exist, as the so called “European Hydrogen backbone”. As building a completely new pipeline grid is economically not justifiable, a dual-way strategy of repurposing natural gas (NG) pipelines and newly built pipelines is intended.
Long distance pipeline grids require regular maintenance and repairs. For NG pipelines in-service welding is state of the art. Concepts such as hot-tapping (drilling into pressurized pipelines) and “stoppling” (sealing off pipeline sections after installing bypasses or pressure relieves) allow the repair of damaged pipeline sections or the installation of new branches without shutting the pipeline down, which in most cases isn’t possible from an economic standpoint.
The EIGA 121/14 guideline already pointed out in 2014 that “A hydrogen hot-tap shall not be considered a rou-tine procedure, […]”. This shows that the determination of the transferability of these repair concepts to hydrogen pipelines is of utmost importance. Due to the degrading effects of hydrogen on mechanical properties, commonly referred to as “hydrogen embrittlement” it is necessary to understand and investigate the occurring effects. In the special case of repair welding on in-service hydrogen pipelines an increased hydrogen uptake due to a large heat input and microstructural changes in the material needs to be considered. Therefore, material degradation must be investigated to determine whether modifications of repair procedures are necessary to ensure a reliable and safe hydrogen transportation via pipelines.
For this reason, this paper gives an overview on existing weld repair concepts and its risks and limitations in terms of hydrogen absorption and possible embrittlement effects when transferred to hydrogen pipelines. The complexity lies in a large variety of materials (low alloyed steels), pipeline diameters and corresponding weld-ed joints. The material compatibility of materials in used (repurposed NG-pipelines) and new condition must be investigated. Particularly for repurposed/used pipelines the effect of a pre-matured/corroded inner surface and sometimes insufficient documentation of the material “history” needs to be considered.
An overview on ongoing and completed R&D-projects with respect to repair concepts for hydrogen pipelines and hydrogen effects on pipeline materials is given.