Duty Conditions First: Why Material Selection is the Most Critical Decision in Any Hydrogen Project

The UK hydrogen pipeline is accelerating faster than many engineers expected. Specifying the wrong pipework material for the actual duty is the single most consequential error on a hydrogen project. Here is how to get the decision right from the outset.

The UK government has set a target of up to 10 GW of low carbon hydrogen production capacity by 2030, with at least half from electrolysis (DESNZ, 2024). The second Hydrogen Allocation Round has already shortlisted 27 electrolytic projects across England, Scotland and Wales, representing approximately 765 MW of production capacity (DESNZ, 2025). HAR3 and HAR4 are confirmed for launch in 2026 and 2028 respectively, with up to 1.5 GW of additional capacity expected to be awarded (gov.uk, 2025). These are not distant ambitions. They are funded, contracted projects moving towards final investment decisions now.

For consulting and specifying engineers, that acceleration creates an immediate problem. Hydrogen is not a straightforward medium. Its molecules are small, its permeation behaviour through non-metallic materials is distinctly different from water or conventional process fluids, and its interaction with metallic structures introduces embrittlement risk that has no parallel in most of the pipework sectors these same engineers have designed for previously. Getting material selection right at FEED stage is far less costly than correcting it during construction or, worse, during operation.

The principle that should govern every hydrogen pipework specification is simple: start with the duty conditions, not with a preferred material. Pressure, temperature, fluid state, purity requirements, exposure duration and the consequences of a leak are all inputs that must precede any material shortlist. There is no universally correct answer for hydrogen pipework.

For low-pressure electrolyte and process water duties within green hydrogen production facilities, PE100 has an established track record. Non-metallic pipes can effectively avoid the hydrogen embrittlement that affects metal pipework. PE100 is characterised by high resistance to slow crack growth and very good chemical resistance, and it is joined by butt fusion and electrofusion techniques that produce a continuous, joint-integrity-verified run. For larger diameter applications, AGRU XL PE100 pipework extends these properties to the high-volume flow duties found in major electrolysis plant and industrial cluster infrastructure.

Where the process stream involves aggressive ancillary chemicals, deionised water or high-purity media in ancillary systems, PVDF becomes the preferred candidate. AGRU PVDF combines good mechanical and thermal properties with excellent chemical resistance and can be processed without additives, which is critical for high-purity process integrity. The material's density and crystalline structure give it notably lower permeability to many gases compared with polyolefin alternatives, an important property where trace gas contamination of a sensitive process stream must be controlled.

Polypropylene offers a cost-effective solution for fume extraction, chemical drainage and lower-duty process lines within the same facility. PP-H and PP-R are standard materials for these duties and carry broad chemical resistance that suits the reagent streams present in electrolyser plant.

Valve selection demands the same rigour. In hydrogen and hydrogen-adjacent process duties, fugitive emissions are not merely an environmental concern: they are a safety-critical performance parameter. SwissFluid fully lined process valves carry TA-Luft (VDI 2440) and ISO 15848-1 certification, with leak-free performance across a pressure range of 1 mbar to 16 bar and a temperature range of -40°C to +200°C. That certification means the stem seal has been independently verified against an internationally recognised fugitive emissions standard, not simply tested to the manufacturer's own preferred conditions. For engineers writing performance specifications, named compliance to ISO 15848-1 is the verifiable standard to call up.

For closed and emission-free sampling on electrolysis plant and ancillary chemical handling lines, SwissFluid inline sampling valves carry the same ISO 15848-1 and TA-Luft stem sealing standard. Closed sampling eliminates the personnel exposure and potential release events that open sampling creates, directly reducing both safety risk and fugitive hydrogen loss.

The jointing method is as important as the pipe material itself. PE100 butt fusion and electrofusion, when carried out with calibrated, traceable equipment and formally trained operatives, produce joints whose long-term integrity has been demonstrated across decades of water and gas network service. For PVDF, infrared butt fusion is the appropriate technique. For PP, socket fusion and butt fusion are both well established. All of these techniques require the correct tooling and trained personnel. Specifying the material without also specifying the jointing standard and the installer competence requirement leaves a gap in the design intent that site conditions will fill unpredictably.

One final point for engineers writing specifications for hydrogen projects within industrial cluster programmes such as HyNet or the East Coast Cluster: the infrastructure delivery timescales are tight. HAR1 projects are expected to become operational between 2025 and the end of 2026 (gov.uk, 2024). Material and equipment lead times, particularly for specialist PVDF and large-diameter PE100, are a programme variable that must be held in the design risk register from day one. Deep UK stock, held domestically and available for next-day delivery, is not a procurement convenience: it is a schedule protection measure.

IPS Flow Systems holds substantial UK stocks across PE100 including AGRU XL, PVDF, PP and the associated valves and fittings needed to complete a hydrogen process system. A technical sales engineer with sector experience can review a duty register at FEED stage, confirm material compatibility and provide the documentation support that a well-managed specification requires.

References

1. Department for Energy Security and Net Zero (DESNZ), Hydrogen Net Zero Investment Roadmap (2024): UK government target of up to 10 GW of low carbon hydrogen production capacity by 2030, with at least half from electrolysis https://www.gov.uk/government/publications/hydrogen-net-zero-investment-roadmap/hydrogen-investment-roadmap-leading-the-way-to-net-zero
2. DESNZ / gov.uk, Hydrogen Allocation Rounds (2025): HAR2 shortlist contains 27 electrolytic hydrogen projects across England, Scotland and Wales representing approximately 765 MW of production capacity https://www.gov.uk/government/collections/hydrogen-allocation-rounds
3. Protium Green / gov.uk Industrial Strategy confirmation (2025): HAR3 and HAR4 confirmed for launch in 2026 and 2028 respectively with up to 1.5 GW of capacity expected to be awarded https://protium.green/what-are-the-hydrogen-allocation-rounds/
4. gov.uk, Hydrogen Allocation Rounds (2024): HAR1 projects confirmed in Autumn Budget 2024 with £90 million in capital grant support and over £2 billion of revenue support; expected to become operational between 2025 and end of 2026 https://www.gov.uk/government/collections/hydrogen-allocation-rounds
5. ResearchGate, Molecular dynamics investigations into the hydrogen permeation mechanism of polyethylene pipeline material (2022): Non-metallic pipes can effectively avoid the hydrogen embrittlement of metal pipes when transporting hydrogen https://www.researchgate.net/publication/365458774_Molecular_dynamics_investigations_into_the_hydrogen_permeation_mechanism_of_polyethylene_pipeline_material
6. AGRU, Plastic materials in AGRU production (2024): AGRU PE100-RC is characterised by very high resistance to slow crack growth and very good chemical resistance https://www.agru.at/en/company/materials
7. AGRU, Plastic materials in AGRU production (2024): AGRU PVDF is a highly crystalline non-reinforced plastic that combines good mechanical, thermal and electrical properties with excellent chemical resistance and can be processed without additives https://www.agru.at/en/company/materials
8. IPS Flow Systems knowledge base / Swissfluid SBV Ball Valve datasheet (2025): SwissFluid fully lined SBV Ball Valves are leak-free across the full pressure and temperature range of 1 mbar to 16 bar and -40°C to +200°C, with maintenance-free stem seal in accordance with TA Luft (VDI 2440) and DIN EN ISO 15848-1 https://www.ipsflowsystems.com/knowledge-base/what-is-swissfluid-and-what-products-do-they-offer-
9. Swissfluid AG, Sampling Valves and Systems brochure (2025): SwissFluid inline sampling valves feature zero stem leakage provided by an innovative stem sealing mechanism according to EN ISO 15848-1 and TA-Luft (VDI 2440 / VDI 3479) https://www.swissfluid.com/pdfs/brochure_swissfluid_sampling-valves-and-systems.pdf
10. Excelplas, Is polyethylene PE100 pipe really the best pipe for hydrogen transport (2023): Hydrogen molecules are small and have a high tendency to permeate through non-metallic materials https://excelplas.com/is-polyethylene-pe100-pipe-really-the-best-pipe-for-hydrogen-transport