In order to investigate the steel grades currently used in Germany, fracture mechanics tests under pressurized hydrogen conditions were carried out as part of the DVGW research project SyWeSt H2. The aim was to compare the results found in the literature, such as those on which ASME B 31.12 is based, and to validate and, if necessary, optimize their applicability to the steel grades used in Germany.
The fracture mechanics tests with hydrogen were carried out on typical pipe steel grades used in high-pressure gas pipelines in Germany. The tests carried out confirm the results from the literature and show that the influence of the material structure and the associated different ductility properties have only a very minor effect on crack growth within the scope of the usual variations. The static fracture mechanics tests also performed show that the minimum fracture toughness required by ASME B 31.12 is clearly met by both current and older piping materials. Fracture mechanics calculations using the test results according to DVGW Code of Practice G 464 show sufficiently conservative results for typical primary static loads.
With the results of the fracture mechanics tests of the DVGW research project SyWeSt H2 and the fracture mechanics calculations according to DVGW Code of Practice G 464, the hydrogen suitability of high-pressure gas pipelines can be well demonstrated for typical, primarily static use, even for higher-strength materials.
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