Introduction
Hydrogen and carbon capture are no longer on the horizon. They’re active project categories now — in India and globally.
The government’s National Green Hydrogen Mission has set targets that require serious industrial infrastructure. Carbon capture feasibility studies are underway at Indian refineries, fertiliser plants, and power generation facilities. Green hydrogen corridors are being planned. Blue hydrogen projects tied to CCS are in early engineering phases.
The procurement activity that follows this project pipeline will include thousands of valves. And here is where the industry faces a challenge it hasn’t fully reckoned with yet: the specifications for hydrogen and carbon capture valves are genuinely different from the specifications that experienced oil and gas buyers have used for decades. Different in ways that aren’t obvious from a standard catalogue review. Different in ways that can result in valve failures that are expensive, hard to diagnose, and in some cases dangerous.
This guide is written for project engineers, procurement managers, and technical teams who are beginning to encounter these requirements. It covers the service conditions, the material and design implications, the standards that apply, and the qualification questions that every buyer must raise with a supplier before committing to a purchase order.
Part 1 — Hydrogen Service: Why Standard Specifications Fall Short
What Makes Hydrogen Different
Hydrogen is the smallest molecule in existence. That single fact drives most of the specification complexity.
Because hydrogen molecules are so small, they permeate through materials that hold other gases completely. Standard elastomer seals that perform reliably in natural gas or nitrogen service allow hydrogen to pass through at rates that create real fugitive emission problems. Standard O-rings that seal perfectly under pressure can suffer explosive decompression damage when pressure is rapidly reduced — the hydrogen dissolved in the elastomer under pressure expands faster than the material can accommodate, causing blistering, cracking, or rupture.
The same permeability affects metallic materials. High-strength steels that perform perfectly in general oil and gas service can absorb hydrogen atoms and become brittle — a phenomenon called hydrogen embrittlement or hydrogen-induced cracking (HIC). This doesn’t happen at low concentrations under low pressure, but as hydrogen partial pressures increase, the risk to standard carbon steel and some alloy steels becomes real and well-documented.
Material Requirements for Hydrogen Service Valves
Body and pressure-containing components: Standard WCB carbon steel is not automatically disqualified for hydrogen service, but it requires careful evaluation. For high-pressure hydrogen — particularly above 100 bar — the risk of hydrogen embrittlement increases with hardness, and some heat treatments used to achieve high strength create microstructures more susceptible to cracking. Material selection should follow ASME B31.12 hydrogen piping guidelines, which categorise allowable materials and hardness limits.
Austenitic stainless steels — CF8 (SS 304) and CF8M (SS 316) — are generally more resistant to hydrogen embrittlement than carbon steels and are commonly specified for hydrogen service. However, they are not completely immune, particularly at very high pressures and in the presence of stress concentrations.
Duplex and super duplex stainless steels require careful evaluation for hydrogen service. Their high strength comes partly from their ferrite content, which is more susceptible to hydrogen embrittlement than the austenite phase.
Stem and fastener materials: Bolting and stem materials in hydrogen service should avoid high-strength alloys with hardness above the limits specified in NACE MR0175 for sour service — the hydrogen embrittlement risk mechanism is similar enough that the same hardness limits are a reasonable conservative starting point.
Seat and seal materials: This is where hydrogen service catches many buyers by surprise. Standard PTFE performs well in hydrogen service — its chemical resistance is good and hydrogen permeability, while present, is manageable. RTFE (filled PTFE) also performs adequately in most hydrogen service conditions.
Elastomeric seats and seals — EPDM, NBR, Viton — require individual evaluation for the specific hydrogen partial pressure and operating conditions. RGD (rapid gas decompression) resistance is not a standard property of general-purpose elastomers. Some specifically formulated grades are available with improved RGD resistance, but this needs to be specified explicitly with the supplier — it is not a default.
Fugitive Emissions Requirements
Hydrogen’s low molecular weight makes stem seal fugitive emissions a real concern. The same seal design that achieves ISO 15848 Class B performance in hydrocarbon service may not meet the same classification in hydrogen service, because hydrogen’s permeability through the stem packing is fundamentally higher.
For hydrogen pipeline and storage applications where leak minimisation is a safety requirement, stem seal performance must be evaluated and tested specifically for hydrogen service — not assumed from natural gas or nitrogen test data.
Part 2 — Carbon Capture and Storage: The Supercritical CO₂ Challenge
Why CO₂ Valves Are a Specialised Category
Carbon capture projects involve compressing captured CO₂ to supercritical conditions — above 73.8 bar and above 31°C — for transport by pipeline and injection into geological storage. In this supercritical state, CO₂ behaves as a dense fluid with properties of both a gas and a liquid. It’s an excellent solvent. And that solvent behaviour creates problems for valve materials that aren’t obvious from CO₂’s reputation as a relatively benign gas at ambient conditions.
Elastomer degradation: Supercritical CO₂ penetrates elastomers and acts as a plasticiser — it softens and swells standard rubber compounds significantly more than natural gas or nitrogen at equivalent pressures. Nitrile (NBR) rubber, which performs well in oil and gas service, swells substantially in CO₂ service. EPDM also swells. Viton (FKM) performs better but still requires evaluation at specific operating conditions. FFKM (perfluoroelastomers) and specially formulated CO₂-resistant grades are available but significantly more expensive.
Rapid gas decompression: When a valve or vessel is depressurised after being under supercritical CO₂, the CO₂ dissolved in elastomeric seals expands. If the depressurisation rate is too fast, this expansion can blister, crack, or destroy the seal — potentially on the first cycle. Valves for CCUS service must use either CO₂-qualified elastomers with documented RGD resistance, or non-elastomeric seals (PTFE or metal-to-metal designs) that avoid this failure mode entirely.
CO₂ corrosion with water: Dry CO₂ is relatively benign for carbon steel at moderate temperatures. Wet CO₂ — CO₂ in the presence of water — is corrosive because it forms carbonic acid. In carbon capture pipelines, the CO₂ stream coming from the capture unit may carry moisture until it’s dried downstream. Valves in the wet CO₂ section need body materials that resist carbonic acid corrosion — typically stainless steel or internally coated carbon steel bodies.
Impurities in captured CO₂: The CO₂ stream from a capture unit is rarely pure. It may contain H₂S, SO₂, NO₂, O₂, and other trace species depending on the source — a refinery flue gas versus a natural gas processing stream versus a power plant. These impurities change the corrosivity of the stream significantly. Valve specifications for CCUS must account for the actual stream composition, not assume pure CO₂.
Design Considerations for CCUS Valves
Valve design choices for CCUS service tend toward metal-seated or soft-seated-with-qualified-elastomers configurations. The operating pressure range in supercritical CO₂ transport — typically 80 to 150 bar — falls comfortably within ASME Class 600 or Class 900 for most pipeline sizes, so pressure rating is rarely the limiting factor. Material compatibility and seal integrity under CO₂-specific conditions are the real engineering challenges.
Ball valves with trunnion mounting are commonly specified for mainline CCUS isolation service — the same reasoning that makes them appropriate for high-pressure gas pipeline service generally. The critical additional requirement is that the floating seat design must accommodate CO₂-compatible seating materials.
Part 3 — Questions Every Buyer Must Raise With Suppliers
Whether you’re buying for a hydrogen project or a carbon capture application, the following questions distinguish suppliers who have genuinely thought through these requirements from those who are adapting standard oil and gas answers to fit.
“What testing have you done specifically for hydrogen service?” A manufacturer who has validated their valve in hydrogen service can point to hyfadrogen-specific fugitive emissions testing, RGD testing on their seat and seal materials in hydrogen, or third-party qualification for a hydrogen project. A manufacturer who hasn’t done this work will describe their general oil and gas capabilities. Both are honest answers. Only the first one is appropriate for hydrogen service.
“Which elastomers in your seat and seal design have been RGD tested, and to what standard?” ISO 23936-2 covers non-metallic materials for use in equipment for petroleum and natural gas industries, including RGD resistance evaluation. Ask which specific elastomer grades have been tested, to what standard, and at what test conditions. If the supplier can’t provide this, the seal design hasn’t been validated for high-pressure gas decompression service.
“What is your material traceability for body and trim components, and how do you verify compliance with hydrogen service hardness limits?” For hydrogen service, hardness control of bolting, stems, and body components matters. Ask for the hardness verification process — specifically whether hardness is checked by the manufacturer or assumed from material certification alone.
“For CO₂ service, what is your experience with supercritical conditions, and what seal materials do you specify?” If a supplier immediately names a standard elastomer (NBR, Viton) without discussing CO₂-specific qualification, they haven’t worked through the problem. A qualified supplier will discuss their specific CO₂-compatible seal material selection and reference either project experience or test data.
“What third-party agencies have witnessed qualification testing for these service conditions?” DNV, Bureau Veritas, TÜV, and similar agencies can witness and certify valve testing for special service conditions. For hydrogen and CCUS applications, third-party witnessed qualification testing provides a level of assurance that manufacturer self-certification alone cannot.
Part 4 — Where Established Manufacturers Fit in Emerging Applications
It’s worth being direct about something that isn’t always said clearly in industry discussions about hydrogen and carbon capture.
These are emerging applications. The number of valve manufacturers globally who have accumulated extensive field-validated experience specifically in supercritical CO₂ pipelines or high-pressure gaseous hydrogen is genuinely small. Most of the industry is at the stage of adapting existing product lines to meet these requirements — some rigorously, some less so.
For project engineers specifying valves for hydrogen or CCUS applications, the practical question isn’t “has this manufacturer supplied 50 hydrogen projects” — most suppliers haven’t, because there aren’t 50 hydrogen projects with valve procurement history yet. The practical question is whether the manufacturer has the underlying engineering discipline, material traceability, testing rigour, and documentation capability to develop a credible solution for these service conditions — and whether they’re honest about the additional qualification work required rather than simply applying their oil and gas catalogue to a new application.
Flowjet Valve, based at GIDC Kathwada, Ahmedabad, is an example of an established industrial valve manufacturer — with over 30 years of manufacturing experience, API 6D approval, fire-safe certification, NACE MR0175 sour service capability, and third-party inspection by DNV and Bureau Veritas — whose core manufacturing discipline and quality systems provide the foundation that hydrogen and CCUS projects will require from their valve suppliers.
For standard oil and gas service — high-pressure ball valves, fire-safe designs, sour service, pipeline applications — Flowjet Valve’s capabilities are well established and documented. For emerging hydrogen and CCUS-specific requirements, buyers working with Flowjet Valve should have the technical conversations described in this guide: specifically what hydrogen or CO₂ service qualification has been completed, what materials are proposed, and what additional testing may be appropriate for the specific application.
That conversation — between an experienced industrial valve manufacturer and a technically informed buyer — is exactly how the industry will develop credible domestic supply capability for these applications as the project pipeline develops.
Summary
Hydrogen and carbon capture valves are not standard oil and gas valves with a different label. The service conditions — hydrogen embrittlement, molecular permeability, RGD risk, supercritical CO₂ solvent behaviour, stream impurities — are genuinely distinct and require specific material selections, design validation, and testing that go beyond what a standard catalogue specification provides.
The qualification questions in this guide are the right starting point for any buyer beginning to engage with these requirements. An experienced supplier will welcome them. A supplier who isn’t prepared for them is not the right supplier for these applications — regardless of how strong their general oil and gas credentials are.
India’s hydrogen and carbon capture project pipeline is developing. The manufacturers who will supply it are those who engage with the technical requirements seriously now — and the buyers who specify these projects correctly will be the ones who asked the right questions early.
Q: What valve specifications are required for hydrogen service? Hydrogen service valves must address three critical concerns: hydrogen embrittlement of metallic components, fugitive emissions from stem seals and body joints, and the extreme permeability of hydrogen through standard elastomers. Body and trim materials must be selected to resist hydrogen-induced cracking (HIC) and sulphide stress cracking (SSC) where applicable. Seat and seal materials must be compatible with hydrogen at operating temperature and pressure. Standards include ASME B31.12 for hydrogen piping, NACE MR0175/ISO 15156 for sour hydrogen service, and ISO 15649 for piping in petroleum and natural gas industries.
Q: What makes carbon capture valve requirements different from standard oil and gas? Carbon capture and storage (CCS/CCUS) valves handle supercritical CO₂ — a state that is neither a gas nor a liquid and behaves differently from both. Supercritical CO₂ is a highly effective solvent that degrades standard elastomers rapidly, extracts lubricants from stem threads, and can cause rapid gas decompression (RGD) damage in rubber seals during depressurisation. Valves must be specified with CO₂-compatible seal materials, RGD-resistant elastomers where used, and materials that are not susceptible to CO₂-accelerated corrosion in the presence of water.
Q: Which standards apply to valves for hydrogen pipelines? Key standards include ASME B31.12 (hydrogen piping systems), ISO 15649, API 6D (pipeline valves), ASME B16.34 (pressure-temperature ratings), and NACE MR0175/ISO 15156 for sour service. For fugitive emissions requirements, ISO 15848 and TA-Luft govern stem seal performance. Fire-safe requirements follow API 607 and API 6FA. Valve materials must comply with ASME Boiler and Pressure Vessel Code Section VIII and relevant hydrogen service material requirements.