Preparation and testing

Safety is at the heart of everything we do, therefore, to determine whether we could use the Grangemouth to Granton pipeline to transport hydrogen, we carried out surveys and checks of the pipeline. We are working closely with the HSE, andhave submitted our Case for Safety (CfS) which has undergone the same review process as our natural gas safety case. Read on to find out more about the tests we did in advance of the live trial below. 

First, we carried out a survey to understand how deep it is and to check the condition of the coating on the pipeline. 

Then, we put pipeline inspection gauge (PIG) traps both ends of the pipeline. The traps allowed us to push a PIG through the pipeline using compressed air, clearing debris and checking for any damage or dents. 

Watch a pipeline inspection gauge being inserted into the Grangemouth to Granton pipeline.

Switching from natural gas to hydrogen will require some changes to the way Local Transmission System (LTS) pipelines are operated and managed. 

Typical natural gas network activities such as live welding, drilling and venting are incredibly important to maintain an uninterrupted supply to customers. Changes to the procedures for these operations are required because hydrogen has different properties than natural gas. 

To find out what needs to be changed, we carried out development and testing at The Welding Institute (TWI) in Cambridge and DNV Spadeadam test site. 

We examined how hydrogen gas impacts pipeline materials, welds, and defects of various ages and conditions. By comparing tests in both inert and hydrogen environments, we can understand how hydrogen affects pipeline steel, which has improved design and operational standards before the live trial begins. 

Testing at TWI

In a TWI lab in Cambridge, 700 tests were being carried out on three different LTS pipe samples. These tests helped us understand if the pipeline material is affected by exposure to hydrogen, and if so, in what ways. 

Testing at Spadeadam

Meanwhile, at DNV's facility in Cumbria (pictured) we conducted the following full-scale testing to understand how pipelines and fittings behave with 100% hydrogen vs natural gas.

Burst and fatigue testing involves adding defects into pipe sections and increasing the pressure until they fail. This helps us understand the safety margins and maintenance needs for LTS pipelines.

Vent and flaring tests check how noise and thermal behaviour change when venting hydrogen compared to natural gas.

Performance testing of existing pressure reduction equipment will help us understand if these systems can work with hydrogen which is less energy dense. This lower density means more hydrogen will need to flow through to meet today’s demand.

Fatigue testing of small-bore connections checks how small connections hold up to hydrogen exposure and vibration, guiding how we design fittings on pipelines.

A hot works trial tested how we can safely make new connections on live hydrogen pipelines. This includes installing welded or grouted tees, which are important because they connect pipes together and can change the direction of where the gas is flowing, allowing new connections or communities to be connected to the network.

The purpose of these tests is to develop safe procedures which we’ll later be able to prove during our live trial of LTS Futures.

Summary

We are pleased to confirm that all these tests have been carried out successfully and have allowed us to progress to the live trials in Summer 2025.   

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