f SIF Discovery Project - Hydrogen Barrier Coatings for Gas Network Assets, Technical Summary Report: Hydrogen Barrier Coatings

This report is the Technical Summary Report of the SIF Discovery project (10022648) Hydrogen Barrier Coatings for Gas Network Assets. This report summarises the hydrogen barrier coatings work packages undertaken in the project which were led by Ultima Forma Ltd with inputs from National Grid Gas Transmission.
Around 23 million homes in UK are currently heated by natural gas, supplied via the National Transmission System. Green hydrogen, generated via renewable energy, has potential to be a zero-carbon replacement for natural gas for heating. Re-purposing the existing National Transmission System for the transmission of hydrogen gas in lieu of natural gas would provide resilience and storage, rather than relying on transient production. However, hydrogen has been shown to embrittle certain pipeline materials thereby reducing allowable operating parameters. Hydrogen barrier coatings applied to the internal surface of the pipeline assets could prevent the need to replace the assets and/or enable the operation of the network in a flexible and optimised manner.
This report builds on and summarises the recommendations arising from project deliverables D1: Potential Coating Materials Their Properties And Application Technologies, D2: Use Cases Summary Report and D3: Analysis of Potential Coating Solutions. From D1, zinc, cadmium, copper, tin, aluminium and nickel were identified as strong candidate materials. From D2, pipework, girth welds, valves and filters were identified as high-priority assets able to provide diverse requirements. From D3, electroplating, metal spraying and hot-dipping were identified as candidate coating technologies. These are all therefore further explored within this report but brought together to find solutions for the use cases and the technologies best suited for the candidate materials. Additionally, due to the importance of the underlying surface quality prior to coating, a section within the report was devoted to looking at surface preparation methods. This included paint removal, chemical treatment and epoxy coating.
After bringing the various elements together it is clear that different technologies are suitable for different use cases. As zinc is suitable for all proposed coating technologies, coating zinc is very mature and zinc is cheaper than tin, it is recommended that further research be carried out on the hydrogen permeability of zinc. As hot-dipping is only suitable on the uncoated or paint striped steel and is unsuitable for many candidate materials it should likely not be a priority for further investigation and the focus should instead be on electroplating and cold spraying. For these technologies, copper, tin, cadmium and nickel are suitable. Cadmium has a risk of toxicity, tin is more expensive, and nickel has a risk of embrittlement when not part of an alloy, therefore, promoting copper as the next most suitable candidate material for further research.
This Discovery phase has identified a number of candidate materials and application processes in order to successfully mitigate the risk of hydrogen to the existing National Transmission System and to allow for a greener hydrogen transition. A detailed plan for validating these processes and technologies has been made and set out in the follow-on Alpha phase application.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.