go to top scroll for more


Projects: Projects for Investigator
Reference Number NIA_CAD0094
Title Effect of 100% hydrogen on cast iron assets
Status Started
Energy Categories Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas) 50%;
Hydrogen and Fuel Cells(Hydrogen, Hydrogen transport and distribution) 50%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
Cadent Gas
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 May 2023
End Date 31 December 2024
Duration ENA months
Total Grant Value £641,333
Industrial Sectors Energy
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , Cadent Gas (99.996%)
  Other Investigator Project Contact , Cadent Eastern (0.001%)
Project Contact , Cadent North London (0.001%)
Project Contact , Cadent North West (0.001%)
Project Contact , Cadent West Midlands (0.001%)
  Industrial Collaborator Project Contact , Cadent Gas (0.000%)
Web Site https://smarter.energynetworks.org/projects/NIA_CAD0094
Objectives "The gas networks recognise the importance of determining the suitability of iron based materials for use with hydrogen and have developed a programme to undertake this assessment. The programme contains 3 elements: 1. Materials Science Programme – which aims to close the gap in substantive scientific evidence thats available today to contradict existing standards and guidance2. Risk assessment of operating iron pipes with hydrogen – which will re-evaluate the methodology used to manage the risk of iron mains for use with hydrogen Peer Review – where the evidence produced by the programme will be peer reviewed by an appropriate technical panel " "The scope of assessment is relevant to all gas facing iron based assets within the gas distribution networks. The project is utilising an asset identification process which has identified that gas facing iron based assets could be operating up to 7 bar(g). " "Materials Science The scope of this research will assess the suitability of all iron based assets that could be exposed to hydrogen within the GB distribution networks. A robust methodology of identifying gas facing iron based assets has found that iron pipework is only present operating up to 2 barg, components such as ductile and malleable iron valve bodies are operating up to 7 barg, and no iron gas facing components have been identified operating above 7 barg, bounding the scope of the assessment to all iron gas facing components operating up to 7 barg. The question being addressed by this programme is:Are iron based pipes and components operating under their associated distribution pressures more likely to fail in hydrogen service than natural gas?To answer this question, the networks will generate evidence and provide discussion in relation to the following sub-questions: 1. How could hydrogen gas interact with iron?a. Is it mechanistically possible for hydrogen to enter the iron based materials and potentially change its mechanical properties?This will be addressed using calculations of the diffusion behaviour of hydrogenb. At what rate could hydrogen be realistically expected to enter the material? Building on the point above, data will be collected to identify the concentration of hydrogen already present in cast irons found on the network. These values can then be used to calculate the possible rates of hydrogen uptake more accurately into the material. a. Which parts of the metallographic structure does the hydrogen interact with (cast iron is more complex structure than steels and therefore the interaction of hydrogen with different phases of the structure may have implications on an effect on the mechanical properties of the material)  Using Secondary Ion Mass Spectrometry, it is possible to visualise the presence of hydrogen within the metallographic structure of the cast iron. It is also then possible to determine whether more hydrogen is detected in the iron or carbon based phases of the material. b. What is the maximum possible uptake of hydrogen by iron based materials?Literature is available which discussed the electrochemical charging of iron based samples and has characterised the hydrogen content achieved in these conditions.2. Do the mechanical properties of iron based materials change in the presence of hydrogen?a. Experimental test data will be available that investigates the tensile and fatigue behaviour of ex-service cast iron pipe and malleable iron inair and in hydrogen If no significant change in properties is observed, it can be concluded that the presence of hydrogen has had no noticeable effect on the material. The expected hydrogen uptake of the material during these tests can also be calculated and compared to the theoretical values mentioned previously.Risk Assessment It is proposed to model the incident risk of operating cast iron, ductile iron and unprotected steel mains containing hydrogen.The current Iron Mains Risk Reduction Programme (IMRRP) is replacing all iron mains operating at low and medium pressure that are up to and including 8” in diameter that are within 30m of a property, however it is only replacing a small proportion of larger diameter iron mains and does not include within its scope the replacement of steel mains or iron mains that are further than 30m from premises. Some steel mains benefit from cathodic protection and have characteristics similar to high integrity high pressure pipelines however others are unprotected and so are more prone to damage by corrosion and have mechanical as opposed to welded joints. Steel mains are not subject to replacement under the IMRRP.The IMRRP is expected to be completed by the end of 2032, which means that from that date the only iron mains that will be in operation are mains that are larger than 8” in diameter and mains that are more than 30m from property.With a possible large scale transition to hydrogen occurring after 2032 it is important to understand what risk the likely mains population at that date might pose were it to be required to convey hydrogen. Once this is known the information can be used to inform both the hydrogen roll out and future investment plans. There is an existing risk model that is used to assess the iron and steel mains population. It is called the Mains Replacement Prioritisation System (or MRPS). It uses a large amount of asset, asset performance and asset location data to predict the expected incident frequency of individual iron and steel mains enabling replacement work to be targeted on those mains which pose greater risk.It is proposed to adjust the model so that it is able to predict the risk that would be posed were the mains to contain hydrogen instead of natural gas. The modelling process will look at the current 30m distance to property limit as well as the risk posed by pipes of different operating pressure, material, size and operating history and determine how substituting hydrogen for natural gas would change the risk exposure for people occupying premises exposed to iron and steel mains.The modelling will examine all deterioration and ground movement related pipeline failure modes that could result in gas entering premises and potentially igniting.It will look at the risk posed to individuals and to society as a whole of making the change to hydrogen. It will determine whether hydrogen is likely to increase the risk posed. It will quantify this risk and also identify the cause of any increase in risk so that potential mitigations may be identified. This information can be used to inform a potential future investment programme. It will inform decision makers in respect of the trade-off that may be required, of minimising costs that impact consumer bills vs the benefit of maintaining or improving the level of safety.Peer ReviewTo support ongoing hydrogen heat policy decision and trials, the HSE require this evidence to: be in line with the type and weight of demonstration submitted to develop a new standard; include the breadth and depth required of a new standard; be developed with wider industry and technical consultation; and be delivered in a format and made available for wider technical review.The project will arrange for the evidence to be peer reviewed by an appropriate technical panel. "
Abstract "In the UK, cast iron was the material of choice for the gas distribution network pipework up until the 1970s. At this time, it was acknowledged that the susceptibility of cast iron to corrosion was greater than polyethylene or steel pipelines which were available as alternative construction materials. Since 1974, there has been a national strategy to replace cast iron mains with alternative materials, however its scope does not cover all iron mains present within the networks. DESNZ are committed to making a policy decision on hydrogen for heating in 2026. Therefore, there is a need to understand the interaction of cast iron and iron based materials with hydrogen to determine the risks associated with re-purposing cast iron for hydrogen service"
Publications (none)
Final Report (none)
Added to Database 18/10/23