This document DIN CEN TR 17797 is written in preparation of future standardization and provides guidance on how injection of H2 into the gas infrastructure can impact processes from the input of gas into the on-shore transmission network up to the inlet connection of gas appliances.

For hydrogen transmission within the German gas grid, it is imperative to obtain a clearly defined assessment of steel components for hydrogen suitability and relevant implementation in the DVGW Codes of Practice. Within this context, DVGW Code of Practice G 409 (for the conversion of pipelines to hydrogen transmission) and DVGW Code of Practice G 463  (for the construction of new pipelines), for example, have been specifically aligned to hydrogen as a transmission medium. Both these codes of practice may require a fracture-mechanical assessment of pipelines and pipeline components, with fracture-mechanical parameters beingrequired as input variables. So far, it was only in ASME B 31.12 [3] that these parameters were specified in an international code of practice. They specifically involve minimum fracture toughness (KIc) and the description of crack toughness (da/dN) with hydrogen as a medium. However, the parameters specified in ASME B 31.12 were based on investigations on US materials which are verysimilar, but not identical, to the materials used in Germany and elsewhere in Europe. Furthermore, the conversion of existing older natural gas pipelines (comprising older materials) is of very considerable interest particularly for the scope of application of the DVGW Code of Practice, although a direct transferability of the US investigations was considered to be problematic. Hence, within the context of the DVGW’s extensive SyWeSt H2 research project, fracturemechanical investigations were performed specifically for the pipeline steel grades used in Germany (and, in some cases, elsewhere in Europe) with hydrogen as a medium. The objective of this project was to compare the established fracture-mechanical parameters with the results on which ASME B 31.12 is based for the purpose of validating their application to steel grades used in Germany and, where applicable, drawing up a modified correlation for crack growth.

This Technical Rule G 260 specifies the requirements for the quality of fuel gases used in the supply of the general public with gas and sets the parameters for gas delivery, gas transportation, gas distribution, gas storage, operation of gas plants/systems and gas appliances for commercial and industrial gas applications as well as for development, standardization, and testing. Gases transported in separate pipelines which are not used in the supply of the general public, or are used as energy carrier or resource, and/or are used in special gas appliances are not subject to the scope of this Technical Rule.

This guideline G 407 shall apply to the conversion of pipelines made from steel to hydrogen-containing, methane-rich gases (2nd gas family) or hydrogen (5th gas family) in accordance with DVGW Code of Practice G 260 up to an operating pressure of 16th and ends with the main shut-off valve, the custody transfer point to DVGW G 600 (A), respectively to G 614.1 (A) (including the additions detailed in DVGW Guideline G 655). This guideline can also be applied to the conversion of steel gas pipeline operated with gases that do not conform to the specifications of DVGW Code of Practice G 260 when taking into account the gases’ specific characteristics and, if applicable, other existing regulations. The respective guidelines on pipeline conversion shall be consulted for networks using different pipeline materials (e.g., plastic and steel).

This guideline G 408 shall apply to the conversion of pipelines made from plastic to hydrogen-containing, methane-rich gases (2nd gas family) or hydrogen (5th gas family) in accordance with DVGW Code of Practice G 260 up to an operating pressure of 16 bar and ends with the main shut-off valve, the thematic threshold to DVGW Guideline G 655. This guideline G 408 can also be applied to the conversion of plastic gas pipeline operated with gases that do not conform to the specifications of DVGW Code of Practice G 260 if the gases’ specific characteristics and, if applicable, other existing regulations are taken into account. The respective guidelines on pipeline conversion shall be consulted for networks using different pipeline materials (e.g., plastic and steel).

G 452‑2 Technical Rule ‑ Standard 08/2020

G 452‑3 Technical Information ‑ Guideline 03/2021

In conjunction with DIN EN 1594, this Technical Rule G 463 applies to the planning and construction of steel high pressure gas pipelines with a design pressure of more than 16 bar for supplying gas to the general public as well as to connected energy facilities on company premises and in the field of commercial gas application of gases of the 2nd and 5th gas family as defined by DVGW Code of Practice G 260. The scope of application has no upwards limitation in terms of the technical parameters nominal diameter and design pressure. This Technical Rule can be applied mutatis mutandis to the construction of high pressure gas pipelines which do not conform to the specifications of DVGW Code of Practice G 260, provided that the specific characteristics of the gases or, if applicable, other already existing technical sets of rules are taken into account.

This Guideline G 464 shall apply for the fracture mechanical assessment of steel gas pipelines that already exist or are projected for construction with a design pressure of more than 16 bar for the transportation or distribution of gases of the 5th gas family (hydrogen) as specified by DVGW Code of Practice G 260. This present Guideline G 464 addresses the assessment of an assumed defect; for the assessment of measured defects, the guideline can be applied analogously.