In summer 2025 we completed a first-of-a-kind demonstration on the Grangemouth – Granton pipeline, carrying out the same operational activities on a hydrogen pipeline as we do on our natural gas pipelines today.
We commissioned our pipeline with hydrogen and undertook a series of flow trials confirming all equipment worked as expected. We then started our Live Hot Works demonstrations.
Hot works
The natural gas transmission networks supplies energy to millions of customers in the domestic, commercial, and industrial sectors. An uninterrupted supply of gas to customers is required, and maintenance operations can require live hot works, including welding and drilling.
Following on from our trials at DNV Spadeadam, we successfully added a new welded tee to our pipeline under flowing hydrogen conditions – a world first. In addition to this, a grouted tee was installed and both connections were successfully drilled under pressure (‘hot tapped’) and plugged. The trial has demonstrated that both connection methods currently used on the natural gas network are suitable options for a hydrogen network.
Several project partners supported this body of work and have contributed to its success, including ROSEN, TD Williamson, STATS Group and Pipeline Integrity Engineers (PIE).
Figure 15: Live Welding by TD Wiliamson using ROSEN and PIE welding procedures
Figure 16. Live Welding by TD Wiliamson using ROSEN and PIE
Figure 17: Live Trial Flow Stopping Operation with Stats Group
Figure 18: Live Trial Drilling Operation with TD Williamson
Capacity assessment
An important function of the LTS is to store gas within the pipeline when gas demand is low. This storage is called linepack and gives us a resilient supply to ensure we have enough gas to meet demand during colder periods, when demand is high. During the live trial, we collected data which will be compared against existing models for hydrogen to assess the potential capacity of the Grangemouth to Granton pipeline. This will enable us to understand any storage differences between hydrogen and natural gas.
The outcome of all this work, including a desktop analysis of other selected pipelines throughout the UK and a cost assessment, will give us a blueprint for repurposing the entire LTS to hydrogen, helping to achieve net zero.