Work Package 3: Durability

Leader: Gaz de France

Partners

Commissariat à l’Energie Atomique, CMI, CSM, DBI-GUT, DEPA, Ecole Nationale des Ingénieurs de Metz, GASUNIE, Institut Français du Pétrole, IGDAS, ISQ, STATOIL, TNO, TOTAL and TUBITAK.

Aims and Objectives

The global aim of this Work Package is to establish the acceptable hydrogen (H2) percentage that can be mixed with natural gas (NG), given its effects on the characteristics of each element of the existing natural gas infrastructure, including transmission, distribution and user appliances. This will enable estimates of lifetime for the different networks, identify bottlenecks, as well as solutions to remove bottlenecks, and provide operational guidelines, with the aim of developing sufficient knowledge in order to produce assessment tools.

Current Status

The activities of WP3 are divided into 6 tasks and their current status can be summarised as follows:

• Task 3.1 (State of the Art) details the current state of knowledge on effects of hydrogen on existing materials used in gas carrying infrastructures. (Reported in Deliverable D6 (State of the Art)).

• Task 3.2 (Transmission pipelines) is focussed on the embrittlement by hydrogen of 2 steels (X52 and X70) used for transmission pipelines in the conditions identified by this risk, e.g. in presence of corrosion defects and sharp defects located in the welds. Fatigue behaviour is the main concern. The results will be transferred to WP4 “Integrity”.

  • Some mechanical properties of both steels X52 and X70 were measured. The values of fracture toughness are important parameters. The permeability to gaseous H2 of steel was also measured.

  • The fatigue behaviour of both steels were partly studied (crack initiation and crack propagation) on laboratory samples, either in gaseous H2 or in electrolytic solutions. The intermediate conclusions that 50% H2 in natural gas may not catastrophically damage the steels should be confirmed in the near future. Moreover, the positive effect of O2 in the gas was confirmed.

  • No difference was observed on the values of the burst pressures between burst tests on short pipes with 100% H2 and 100% NG. Moreover, the presence of H2 in the NG had a positive effect on the ductile fracture unstable propagation: increasing the hydrogen content produces a reduction of the toughness requirements to arrest a ductile fracture in the gas pipeline.

• Task 3.3 (Distribution network) is mainly focused on permeability of PE (polyethylene) (PE80 and PE100) and PVC (high impact PVC) and the ageing of PE in presence of H2 in methane, and on reliability of domestic gas meters.

  • The permeability testing on PE laboratory samples is completed. The results were used to calculate the leakage rates on PE pipes at 4 bar distributing a mixture of 80% NG + 20 % H2 as an example; the leakage rates are: 2.3 litre/km/day for H2 and 1.1 litre/km/day for CH4.

  • Ageing tests on PE laboratory samples continue. Intermediate results (ageing tests for 3 months) didn’t show significant effect of H2 on the residual properties of the PE. The slight changes will be confirmed with longer aged samples and compared to actual dispersion on un-aged samples.

• Task 3.4 (Inner grids) studies the hydrogen effect on materials used in houses, like flexible pipes, connections and valves. The work is focussed on the impermeability assessment of these devices.

• Task 3.5 (Durability assessment tool) will start in June 2007, using data from the tasks T3.2 and T3.3.

• Task 3.6 (Coordination) aims to ensure progress with the Tasks and completion of the Work Programme by planning details of specific activities, liaising with Work Package participants, checking milestones, organising deliverables, and assisting integration with other related Work Packages (mainly WP2, WP4 and WP6). The WP3 has also exchanges of information with the HYWAYS European project, with the “H2 delivery programme” of the Department Of Energy (USA) and within the International Partnership on Hydrogen Economy (IPHE).