Project Hydrogen-dependent mechanical properties of the welding microstructure of low-alloy steels for long-distance gas pipelines

31/05/2024

• Challenge
• Objective
• Methods
• Partners

Green hydrogen from renewable energy sources will be a key factor in the achievement of the Paris climate goals. Its effectiveness as an energy carrier depends largely on how hydrogen gets transported. Due to a lack of regulation, safety aspects are a challenge as standardised test procedures do not yet exist. A major problem is the clarification of material compatibility in the existing and new gas infrastructure.

The research project aims to clarify the suitability of low-alloy pipeline steels for hydrogen transport. Insufficient knowledge of weld sensitivity and a lack of standardisation of welded pipeline testing have hampered previous investigations. The project will systematically develop the prerequisites for accurately predicting hydrogen material behaviour.

The methodology involves a series of tests on pipeline materials. The first step is to physically simulate the microstructure of the weld zones. The tests are then carried out under a pressure and an electrochemical hydrogen load, and the diffusion rate of the hydrogen in the microstructures is determined. The characteristic values obtained will be available for use in future FE simulations. The materials will then be subjected to mechanical testing for the effects of hydrogen exposure.

Federal German Ministry for Economic Affairs and Climate Action (BMWK)

Long-distance gas pipelines made of steel are a central component of the sustainable energy industry and are used for the large-scale technical transport of generated hydrogen to consumers. In addition to the conversion of existing natural gas pipelines for hydrogen transport, the construction of new pipelines is being promoted. Almost all pipeline components are welded. However, the hydrogen resistance of weld structures when exposed to gaseous hydrogen environments has not yet been fully clarified. This applies equally to steels in existing pipelines and to new high-strength steel grades. The lack of standardisation of corresponding tests for welded pipelines also does not yet allow an exact prediction of the general suitability of low-alloy pipeline steels for hydrogen transport.

The basis for this is therefore to be systematically developed in this research project. Typical base materials - and for the first time weld structures (HAZ) - are specifically exposed to different hydrogen pressures and then subjected to a tensile test. The physical simulation enables individual microstructures of a weld joint to be analysed separately. The analysis of the respective hydrogen transport behaviour subsequently provides information as to whether simple electrochemical loading can be used to qualify the piping materials for the new hydrogen technologies instead of complex autoclave technology.

In addition to providing reliable properties for materials in general, the project creates the conditions for practical testing in order to quickly assess the behaviour of materials, including welded joints. In addition to material selection, this is also important for the quality assurance of new steels. By transferring the intended research results into technical regulations and guidelines, concrete measures and guidelines for the implementation of the hydrogen infrastructure will be provided.

Partner organisation

Federal Ministry for Economic Affairs and Climate Action (BMWK)

Funding

AiF as part of the programme Industrielle Gemeinschaftsförderung (IGF) of the German Federal Ministry of Economic Affairs and Climate Action