Proposals should:

• Deliver a preliminary inventory of non-steel metallic materials constitutive of the European distribution natural gas grid and deliver a priority ranking analysis to evaluate the most cost-efficient strategy (adaptation or replacement) for each of them;
• Propose a testing approach covering most relevant non-steel metallic grades (cast iron, copper, brass, lead, aluminium) constitutive of European distribution natural gas grids and their different operating conditions (maximum pressure, pressure cycling, etc.). Proposals should cover an extensive range of natural gas/hydrogen blends with a focus on hydrogen contents up to 20%, and 100%. This approach should combine mechanical tests and modelling, e.g. using first principles calculations or fracture mechanics method of hydrogen interaction with the materials. A preliminary bibliographic review should be conducted to identify the gap analysis at the start of the action, taking into account existing results from former and other ongoing projects;
• Propose harmonised protocols and run material tests to measure the mechanical properties affected by the presence of hydrogen and critical for its integration into networks (should include e.g. crack propagation, fatigue, toughness, and impacts on welds and heat affected zones (HAZ)) and impact of chemical composition for grid components. The protocols should be made available to the public and should ensure that all results are comparable between the different testing laboratories involved. It should also, serve as a standardised reference guideline for future investigations.

Following the testing activities proposals should make available a database of gas grid metallic materials’ behaviour in the presence of hydrogen associated with network operating conditions, assessing the compatibility of vintage and new gas pipes. There should also be a plan that ensures the that the database is updated after the project is finished with future testing results. Projects should also identify acceptance criteria including the allowed size of defects, depending on the pressure and hydrogen concentration.