Specifying Pipework for Hydrogen Plants: Getting Material Selection Right Before It Costs You

The UK hydrogen sector is accelerating fast. Engineers specifying process pipework for electrolyser plants and associated chemical handling systems face a narrow window to get material selection right. A wrong call early in design locks in risk for the life of the plant.

The scale of what is being built is significant. The UK government's target is up to 10 GW of low carbon hydrogen production capacity by 2030 (DESNZ, 2024). HAR2 alone shortlisted 27 projects across England, Scotland and Wales representing approximately 765 MW of green hydrogen production capacity, with the potential to secure close to £1 billion in private sector investment by 2029 (DESNZ, 2025). HAR3 and HAR4 are set to launch in 2026 and 2028, with up to 1.5 GW of additional capacity between them (DESNZ, 2025). Every one of those projects contains process pipework. Every metre of it must be correctly specified for the chemical environment it will live in.

The chemical challenge is not trivial. Alkaline electrolysers use a liquid KOH aqueous solution of 20 to 30 per cent as electrolyte, operating at temperatures of 70 to 80°C (IEA TCP H2 Task 43, 2025). Process temperatures in next-generation alkaline plant are expected to rise to 120°C as efficiency improves (AGRU, 2024). PEM electrolysers, meanwhile, require ultrapure water at 60 to 80°C and pressures of 6 to 10 bar (AGRU, 2024). Each technology imposes a distinct and demanding chemical duty on every pipe, valve and fitting in the system.

Material selection is not a procurement decision. It is an engineering decision with long-term consequences. Specifying the wrong material for KOH service, ultrapure water circuits or chemical dosing lines does not simply shorten component life. It creates unplanned downtime, fugitive emission risk and, in the worst case, a safety incident. The four materials that matter most on a hydrogen plant are polypropylene, PVDF, ECTFE and PE100, and each has a distinct role.

Polypropylene is the workhorse of the alkaline electrolyser. It handles dilute and moderate-concentration alkalis and inorganic acids well, and it performs reliably across the temperature range of most internal KOH circuits. Where PP meets its limits, typically at elevated temperature or with highly concentrated or aggressive media, PVDF takes over. PVDF has excellent chemical and physical properties even at low temperatures and is resistant to most inorganic acids and bases, aliphatic and aromatic hydrocarbons, organic acids, alcohols and halogenated solvents, with safe working temperatures from -40°C to +140°C. It is also non-toxic and suited to high-purity applications. For the most aggressive duties, ECTFE offers even better resistance to chemicals than PVDF, especially in alkaline solutions and at higher temperatures, and is highly impact-resistant with virtually no property changes over a wide temperature range.

IPS Flow Systems stocks AGRU industrial piping systems in PP, PVDF and PE across the range relevant to hydrogen plant. AGRU supplies pipes and fittings to large electrolysis plants across Europe and the USA. Their AGRUCHEM industrial piping systems are designed specifically for chemical duties including KOH, acids and ultrapure water circuits. For ultrapure water distribution in PEM plant, AGRU's PURAD system in PP-Pure or PVDF provides the ultra-low leach-out behaviour that ion-sensitive processes demand, manufactured under ISO Class 5 cleanroom conditions.

The valve selection question is equally critical, and it is one that is too often deferred. Process valves handling KOH, chemical dosing streams and corrosive effluent streams must provide zero fugitive emissions. Valves account for a significant proportion of a facility's fugitive emissions, and as regulatory scrutiny tightens, the stem sealing standard is non-negotiable. SwissFluid fully lined ball valves and butterfly valves carry live-loaded, maintenance-free stem seals in accordance with TA Luft VDI 2440 and ISO 15848-1, rated leak-free from 1 mbar to 16 bar across -40°C to +200°C per EN 12266-1 and API 598. Liner options include PTFE, PVDF and PFA to match the chemical duty precisely. These are not premium upgrades. They are the correct specification for a plant where fugitive emission compliance and long-term operator safety are not optional.

For process monitoring and closed sampling, SwissFluid sampling valves provide zero stem leakage in accordance with EN ISO 15848-1 and TA Luft, with no dead space and a design suited to representative sampling from corrosive and aggressive media. This removes the risk of operator exposure during routine sampling operations, which matters operationally and for regulatory compliance under UK COSHH and HSE obligations.

Feed water and bulk water circuits, particularly in coastal and port-adjacent electrolyser projects such as those on the HAR2 shortlist, will call for large diameter PE100 pipework. AGRU XL large diameter PE100 piping handles bulk water transport reliably, jointed by butt fusion and electrofusion in accordance with established standards. Where water quality demands a step up, the transition to PURAD PVDF or PP-Pure is straightforward within the same supplier ecosystem.

The whole-life cost case for getting material selection right at FEED stage is clear. Rework after construction is expensive. An unplanned shutdown on an electrolyser plant that is on a 15-year Low Carbon Hydrogen Agreement revenue contract is far more expensive than that. Consulting engineers who specify the correct thermoplastic at the outset, with verified chemical resistance data, matched standards and a supplier who holds UK stock for delivery when the programme demands it, are the engineers who protect their clients' investments.

IPS Flow Systems has more than 30 years of experience supplying thermoplastic piping systems to chemical, energy and process sectors across the UK and Ireland. The hydrogen sector is a natural extension of that expertise. If you are working on a hydrogen plant specification and want to talk through material selection, approvals or product availability, our sales engineers are ready to help.

References

1. Department for Energy Security and Net Zero (DESNZ), Hydrogen Strategy Update to the Market (2024): UK government target of up to 10 GW of low carbon hydrogen production capacity by 2030 https://assets.publishing.service.gov.uk/media/6761915126a2d1ff18253493/hydrogen-strategy-update-to-the-market-december-2024.pdf
2. Department for Energy Security and Net Zero (DESNZ), HAR2 shortlist announcement (2025): HAR2 shortlisted 27 projects across England, Scotland and Wales representing approximately 765 MW of green hydrogen production capacity, with the potential to secure close to £1 billion in private sector investment by 2029 https://www.energyvoice.com/renewables-energy-transition/hydrogen/uk-hydrogen/569076/uk-green-hydrogen-projects-secure-government-backing-allocation-round-har2-sarah-jones/
3. DESNZ, Hydrogen Update to the Market, July 2025 (2025): HAR3 and HAR4 set to launch in 2026 and 2028 with up to 1.5 GW of additional capacity https://assets.publishing.service.gov.uk/media/6880b2139fab8e2e86160efe/hydrogen-update-to-the-market-2025.pdf
4. IEA TCP H2 Task 43, Recommendations for Safety Distances Methodology for Alkaline and PEM Electrolyzers, Hydrogen Safety Journal (2025): Alkaline electrolysers use a liquid KOH aqueous solution of 20 to 30 per cent as electrolyte at operating temperatures of 70 to 80°C https://hysafejournal.org/articles/10.58895/hysafe.18
5. AGRU, Hydrogen applications page (2024): Process temperatures on next-generation alkaline plant expected to rise to 120°C; PEM electrolysis uses ultrapure water at 60 to 80°C and 6 to 10 bar https://www.agru.at/en/news/innovations/innovations-and-new-products/hydrogen-agru
6. IPS Flow Systems, PVDF product page (2024): PVDF safe working temperatures from -40°C to +140°C, resistant to most inorganic acids and bases, non-toxic and suited to high-purity applications https://www.ipsflowsystems.com/pvdf
7. AGRU, Materials page (2024): ECTFE offers even better chemical resistance than PVDF especially in alkaline solutions and at higher temperatures, highly impact-resistant with virtually no property changes over a wide temperature range https://www.agru.at/en/company/materials
8. AGRU, Hydrogen applications page (2024): AGRU PURAD piping manufactured under ISO Class 5 cleanroom conditions; AGRU supplies pipes and fittings to large electrolysis plants in Europe and the USA https://www.agru.at/en/news/innovations/innovations-and-new-products/hydrogen-agru
9. IPS Flow Systems, SwissFluid knowledge base page (2024): SwissFluid fully lined ball valves carry live-loaded maintenance-free stem seals compliant with TA Luft VDI 2440 and ISO 15848-1, rated leak-free from 1 mbar to 16 bar across -40°C to +200°C per EN 12266-1 and API 598 https://www.ipsflowsystems.com/knowledge-base/what-is-swissfluid-and-what-products-do-they-offer-
10. SwissFluid AG, Sampling Valves and Systems catalogue, via DirectIndustry (2024): SwissFluid sampling valves provide zero stem leakage in accordance with EN ISO 15848-1 and TA Luft, with no dead space https://pdf.directindustry.com/pdf/swissfluid-ag/sampling-valves-systems/105539-1042577.html
11. DESNZ, Hydrogen Update to the Market, July 2025 (2025): Over £400 million of private capital investment committed by hydrogen projects upfront between 2024 and 2026, with over 700 direct jobs created in construction https://assets.publishing.service.gov.uk/media/6880b2139fab8e2e86160efe/hydrogen-update-to-the-market-2025.pdf