A key consideration associated with injecting hydrogen into our network is ensuring the materials used across the network are not impacted by the change in transported gas.  Hydrogen is a smaller molecule than natural gas and can permeate into materials and impact their properties. If utilising the current pipeline design codes, changes in operating parameters would be required if the material capability in hydrogen environments cannot be proven.

It's important that we can operate the network at the same pressures utilised today, to maximise the energy we can transport from producer to user. One of the key operating parameters is pressure and without specific in-hydrogen material testing, current pipeline design codes only allow for the network to be run with hydrogen at reduced pressures.

We’re running this project to evaluate the pipe grades that have been used to construct the NTS, including X42, X46, X52, X60, X65 and X80, to see how they perform with high-pressure hydrogen.

A range of tests are being carried out on the pipes, including on the seam and girth welds, to determine their fracture toughness and fatigue crack growth rates. The tests will use 100% hydrogen at a pressure of 69 bar, and the outputs will be used to demonstrate that the National Transmission System (NTS) can be operated with hydrogen at full NTS pressures.

The project will provide vital data on the performance of carbon steel pipe when exposed to 100% hydrogen and will also provide an understanding of what aspects are essential to safely maintain and operate a hydrogen NTS.

The FutureGrid test facility will be used to demonstrate the ability to convert our network to carry hydrogen. The facility is constructed from decommissioned assets taken from the NTS and the materials tests undertaken in this project has provided the evidence required to enable the test facility to operate at NTS pressures.