Hydrogen is routinely and safely distributed as an industrial gas across the world and in the UK today. An important part of HyDeploy is to make sure that using a blend in existing gas infrastructure which delivers to homes and businesses, is also safe. How blended gas interacts with materials (such as gas pipes) is one of the risk areas that are being assessed.
There is already a good evidence base for many materials, most of which have no chemical interaction with hydrogen. Specific areas under assessment:
- Hydrogen embrittlement of high strength steel is recognised to be a potential issue in materials operating at high pressures and temperatures. At Keele, however, we are dealing with a gas blend of relatively low hydrogen concentration at low pressure and being delivered at ambient temperature. Under these conditions this phenomenon is not considered to be a risk, but a programme of testing is being undertaken to validate this.
- Much of the UK gas network uses plastic (typically polyethylene) pipes, and there are no adverse chemical interactions with hydrogen in these materials. Although very low levels of permeation of gases occurs through such materials, the rates are lower than the regulated safety levels for leakage from pipework and installations. HyDeploy will be building on existing data, developing this current understanding even further. For example, it is working with pipeline specialists to assess how a hydrogen blend could impact on jointing and repair work on plastic pipes.
HyDeploy includes a survey of the materials on the Keele gas network. This will be combined with information from equipment suppliers and existing research into materials interactions. Where further information is required, specific laboratory tests are being undertaken, including work by Keele University materials department. This evidence base will form part of the information supplied in the safety case to the HSE who will decide if HyDeploy can go ahead to a live trial.