Materials Aspects Associated with the Addition of up to 20 mol% Hydrogen into an Existing Natural Gas Distribution Network

The introduction of hydrogen into the UK natural gas main has been reviewed in terms of how materials within the gas distribution network may be affected by contact with up to 80% Natural Gas : 20 mol% hydrogen blend at up to 2 barg. A range of metallic, polymeric and elastomeric materials in the gas distribution network (GDN) were assessed via a combination of literature review and targeted practical test programmes.
The work considered:

• The effect of hydrogen on metallic materials identified in the network
• The effect of hydrogen on polymeric materials identified in the network
• The effect of hydrogen exposure on polyethylene pipeline techniques (squeeze off and collar electrofusion)

The trials concluded that the majority of metallic materials showed no significant deterioration in mechanical (tensile) properties when stored in hydrogen environments compared to those stored in analogous methane or blended gas atmospheres up to 2barg. Polymeric materials showed no deterioration to efficiency of squeeze-off nor collar electrofusion in socket or shoulder orientations following soaking in hydrogen, methane or hydrogen blends.