Why one elastomer family is emerging as a pragmatic path to longer seal life, fewer fugitive emissions, and lower total environmental footprint across hydrogen and carbon capture value chains.

Hydrogen hubs, electrolyser projects, carbon dioxide (CO₂) capture trains, and new storage sites are often framed as sweeping infrastructure stories about pipelines, compressors, and valves.

Subscribe to PII and receive:

Our long-established bi-monthly digital magazine *Process Industry Informer*, featuring exclusive articles, news and updates across the Process Industries, plus commentary from our three industry experts:

Sean Moran

Gavin Smith

Dave Green

PLUS:

• Process Industry Update — our weekly e-newsletter
• PII Podcast
• Special messages from our advertising partners

Subscribe for free now!

But the reliability and emissions performance often hinges on a smaller, less visible component: the seal. In H₂ and CCUS (Carbon Capture, Utilisation, and Storage), valves cycle frequently, face wide temperature swings, encounter aggressive media, and must maintain tightness under pressure.

When a seal fails early, the impact is rarely confined to a maintenance work order; it can mean unplanned downtime, safety risk, product loss, and (critically for sustainability projects) avoidable emissions.

Elastomers, the materials used in seals, sit at the intersection of chemistry, mechanics, and process reality. They must stay resilient (so they keep sealing force), remain compatible with the fluid (so they don’t swell, crack, or soften), and survive pressure and temperature transients (so they don’t blister or tear).

For sustainability-oriented valve service, those demands are amplified. Hydrogen molecules are small and mobile and Super Critical (100%) CO₂ can behave like a powerful solvent under pressure thus capturing amines that can be relentlessly reactive. The industry therefore needs sealing materials that are not only “green” in narrative, but dependable in service – because durability is sustainability.

One elastomer family is increasingly worth a closer look in this context: EPM (ethylene propylene rubber without diene, often referred to as ethylene-propylene or ethylene-polyethylene in some industry shorthand).

Properly formulated, EPM compounds, such as Greene Tweed’s EPM 893, can cover a surprisingly wide range of needs seen across H₂ and CCUS valves, from aggressive capture solvents to dense-phase CO₂, while bringing strong low-temperature flexibility and compelling resistance to rapid gas decompression (RGD) in many designs. The result is a practical pathway to fewer seal changes, fewer leaks, and a lower total lifecycle footprint.

What “Sustainability Service”  Looks Like in H₂ and CCUS

Every additional seal material introduced into a project increases qualification effort, inventory complexity, and the risk of misapplication.

Hydrogen and carbon capture can look like two separate worlds. In practice, they share a common reality: valves operate across production, conditioning, transport, and storage – and the sealing requirements change from one node to the next.

Hydrogen (H₂) environments range from electrolyser skids (wet gases, water management, and often alkaline or PEM-adjacent chemistries) to compression and pipeline transport (dry gas, high pressure, frequent cycling) to storage (salt caverns, above-ground vessels, or liquid hydrogen systems at very low temperature). In each case, the media may be “clean,” but the operating conditions are not: pressure ramps can be steep, temperatures can swing, and the gas’s small molecular size raises the bar for leak-tight designs.

CCUS environments begin in capture units where CO₂ is separated from Flue Gas (often using amine-based solvents) then move into dehydration, compression, and transportation where CO₂ may exist as a high-pressure liquid or dense phase.

Downstream, injection and storage operations introduce additional challenges, such as temperature gradients along wellbores, contact with water, and impurities that vary by source. CO₂ itself is not “inert” to polymers under these conditions; at elevated pressure it can permeate into elastomers and later expand during depressurisation, potentially damaging the seal from within.

Across both value chains, the same valve families show up repeatedly: ball, butterfly, plug, gate, and control valves, along with actuators and instrumentation. The sealing points vary (stem seals, seats, O-rings, gaskets, diaphragm elements), but the underlying material question remains the same: can one elastomer platform deliver chemical compatibility, low-temperature resilience, and pressure-cycle durability without forcing designers into constant tradeoffs?

When a seal fails early, the impact is rarely confined to a maintenance work order; it can mean unplanned downtime, safety risk, product loss, and (critically for sustainability projects) avoidable emissions.

Three Failure Modes That Dominate H₂ and CCUS Sealing

When sustainability projects struggle with sealing, it’s rarely because engineers ignore the problem, rather because the same seal is being asked to do three difficult things at once: resist aggressive chemicals, remain elastic at low temperature, and survive repeated high-pressure gas cycling without internal damage.

1) Chemical resistance: amines, alkaline electrolytes, and “pure” gases that aren’t benign

Amines in CO₂ capture are designed to react with CO₂ , which means they are (by definition) chemically active. Seals exposed to amine solutions (and their degradation products) can experience swelling, softening, extraction of additives, or surface cracking depending on the elastomer chemistry and the specific solvent blend. Even when a seal “survives” in the lab, changes in hardness or volume can push a valve out of its designed compression range, increasing friction, torque, or leakage over time.

Alkaline media such as Potassium Hydroxide (KOH), common in certain electrolyser and balance-of-plant systems, pose a different challenge. High-pH exposure can accelerate chemical attack for some polymers, and it can also magnify any weakness created by temperature cycling or mechanical stress. Compatibility isn’t only about “does it dissolve?” – it’s about whether the elastomer keeps its mechanical properties long enough to deliver stable sealing force.

Pure CO₂ and H₂ sound simple, but high-pressure gases interact with elastomers through permeation and solubility. CO₂, in particular, can plasticise certain polymers under pressure, changing their modulus and sealing behaviour.

Hydrogen adds the challenge of extremely high diffusivity and leak sensitivity. And in real systems, “pure” often comes with caveats: water, oxygen, H₂S, or trace hydrocarbons can appear depending on source and process step, each influencing long-term stability.

2) Low temperature: when elastomers turn from springs into glass

CO₂ transportation and storage can expose valves to low ambient temperatures, Joule–Thomson cooling during pressure let-down, or cold-soak conditions in storage and shipping, as low as -55°C (-67°F) when in liquid form.

Hydrogen systems add their own extremes, especially as projects explore cold gas management and, in some cases, cryogenic liquid hydrogen handling (where elastomers may be replaced by other sealing technologies altogether). 

The engineering issue is straightforward: as temperature drops, many elastomers lose flexibility. If an elastomer approaches its glass-transition region, it stops behaving like a compliant spring and starts behaving like a rigid plastic.

Sealing force can drop, micro-gaps can open, and leakage rates can climb, especially in dynamic locations such as stems. At the same time, repeated cold/hot cycling can accelerate compression set (permanent deformation), leaving the seal unable to “recover” when the hardware moves.

3) Rapid gas decompression (RGD): damage from the inside out

RGD (also called explosive decompression) occurs when a gas dissolves into an elastomer under pressure and then the pressure is released faster than the gas can diffuse back out. Internal bubbles can form, grow, and rupture the polymer network, leaving blisters, fissures, or chunking.

Not every pressure drop produces RGD, but sustainability applications create many of the preconditions: high-pressure CO₂ in compression and pipeline segments, repeated depressurisation during maintenance or operational upsets, and high cycling rates in control or isolation valves.

RGD resistance is not just a material checkbox; it’s a system outcome influenced by compound formulation, seal geometry, hardness, temperature, gas type, and decompression profile. But material choice sets the baseline.

Selecting an elastomer family with inherently favorable gas-diffusion behavior and good tear resistance can substantially widen the safe operating window and reduce the frequency of “mystery” seal failures that only show up after a shutdown.

Which Elastomer Families Are on the Table, and What They Trade Off

Valve designers have no shortage of elastomer options, but sustainability service tends to expose the weak side of each. The goal isn’t to declare one polymer “best” in the abstract; it’s to identify the smallest set of materials that can cover the widest operating envelope with predictable aging behavior.

NBR / HNBR (nitrile and hydrogenated nitrile)
Often valued for good mechanical strength and broad industrial familiarity. However, performance depends heavily on formulation, and chemical compatibility can be limiting in certain capture solvents, mainly polar solvents such as methyl ethyl ketone (MEK) and methyl acetate (MeOAc). Gas service can also challenge some compounds if RGD conditions are severe.

FKM (fluoroelastomers)
Common in chemical and hydrocarbon service, with strong high-temperature capability. In sustainability applications, FKMs can be excellent in some environments but can struggle in others, particularly where low temperature flexibility is required to go under -37°C, or where specific solvents drive swelling or property shifts. As with all families, “FKM” is not a single material; grades vary widely.

FEPM / high-fluorine options (including specialty grades)
Selected when chemical resistance is the dominant need. These materials can perform well in aggressive media, but may come with cost, processing complexity, and in some cases tradeoffs in low-temperature behavior or RGD robustness depending on compound design.

VMQ / FVMQ (silicone / fluorosilicone)
Silicones are known for excellent low-temperature flexibility and are useful where cold sealing is paramount. Their tradeoffs can include lower tear strength and variable resistance to certain chemicals and high-pressure gas conditions, making careful validation essential for CO₂-dense or highly cycled service.

EPDM / EPM (ethylene-propylene families)
These elastomers are widely used in water, steam, and many polar chemical services. EPDM includes a diene termonomer that enables sulphur vulcanisation; EPM is the non-diene version typically cured with peroxides. For H₂ and CCUS valves, these families stand out for their balance of low-temperature resilience and compatibility with many polar fluids, while also offering compound design space to target RGD resistance.

Note: In some valve architectures, designers may shift from elastomers to PTFE-based seats or other engineered plastics to address permeability or temperature extremes. Those materials can be excellent solutions, but when elastic recovery, dynamic sealing, and tolerance to hardware variation are required, elastomers remain indispensable.

Why EPM Is Emerging as a Versatile Workhorse for Sustainability Valves

EPM sits in the ethylene-propylene elastomer family. Unlike EPDM, EPM does not contain a diene termonomer, which changes how it is typically crosslinked and how it behaves in certain aging environments.

In practical valve terms, what matters is that EPM compounds can be tuned – through polymer grade selection, filler system, cure package, and additive strategy – to deliver a combination that sustainability service repeatedly asks for: resistance to many polar chemicals, strong low-temperature elasticity, and robust performance under gas pressure cycling.

From a sustainability lens, that versatility matters. Every additional seal material introduced into a project increases qualification effort, inventory complexity, and the risk of misapplication. A material platform that can credibly span multiple nodes of the value chain reduces waste in procurement and maintenance, cuts the frequency of replacement interventions, and lowers fugitive emissions risk by keeping valves tight for longer.

H2 and CCUS projects are often evaluated through the lens of megatons and gigawatts, but their credibility is also built on operational discipline: tight systems, low leakage, and equipment that lasts.

Amine and capture-solvent exposure: staying stable where “reactive” is the point

In CCUS capture units, compatibility is often evaluated with immersion testing in representative amine blends at controlled temperature for set durations, followed by measurement of volume change, mass change, hardness shift, and tensile properties.

What engineers want to see is not perfection – every elastomer changes somewhat – but consistency in performance: limited swelling, modest hardness drift, and retention of tensile/elongation sufficient to avoid cracking during installation and cycling.

Well-designed EPM compounds like Greene Tweed’s EPM 893 often show favourable stability trends in polar solvent environments because of their saturated backbone and the way formulation can be optimised for extraction resistance.

In practice, that can translate into seals that maintain compression behaviour and torque characteristics over longer intervals in capture-adjacent valves – helping plants avoid the slow drift from “tight and smooth” to “sticky, leaking, and maintenance-heavy.”

Alkaline electrolyzers and balance-of-plant: a quiet compatibility challenge

On the hydrogen side, alkaline systems introduce high-pH exposure – such as to KOH (potassium hydroxide) – where some elastomers may embrittle or lose properties over time. EPM’s saturated backbone and polar-fluid capability give compounders tools to formulate for stability in these environments, particularly when the seal also needs to tolerate temperature cycling and mechanical motion. For project teams trying to standardise materials across skids and ancillary equipment, this is where EPM’s “covers more than one box” value starts to become tangible.

High-pressure CO₂: managing permeation, plasticisation, and decompression

Dense-phase CO₂ is a defining service condition for many CCUS transport and injection systems. Under pressure, CO₂ can dissolve into elastomers and alter their stiffness; during depressurisation, the same dissolved gas can drive RGD damage. The practical consequence is that seals must be selected with the full pressure-cycle story in mind, not only the steady-state pressure and temperature.

EPM compounds engineered for gas service can perform strongly in CO₂ RGD screening, especially when formulation emphasises tear resistance and controlled permeability. In qualification programs, engineers commonly use standardised RGD methods (for example, NORSOK-style or ISO-based approaches) with defined soak pressures, temperatures, and decompression rates, then rate internal cracking or blistering after sectioning the seals.

The key is to test in the relevant gas (CO₂, H₂, or mixed), and at the relevant temperature, because RGD sensitivity is highly condition-dependent. Greene Tweed tested its EPM 893 using a modified version of  ISO-23936-2 Annex B test standard, which is a known standard that outlines the test conditions (see Figure 3) to measure RGD, most commonly used in the Energy sector, as depicted in Figure 2, showing an “all zeroes” rating based on this standard .

Low temperature resilience: where EPM’s elastomer physics helps

Many sustainability assets operate outdoors, in varied climates, and with process upsets that can cool components rapidly. In those scenarios, low-temperature flexibility is not a comfort feature; it is a leak-prevention feature.

When formulated properly, EPM compound’s ability to maintain elastomeric behaviour at lower temperatures helps seals keep contact pressure on seats and stems during cold starts and rapid temperature drops, reducing the odds of transient leakage events that are difficult to detect but costly over time.

The “wide variety of needs” advantage – and the boundaries to respect

No elastomer is universal, and EPM is no exception. But within a large slice of H₂ and CCUS valve duty, particularly where operating temperatures stay below 150°C, EPM can act as a highly consolidating material choice.

As a PFAS-free material choice, it offers H₂ and CCUS companies meet evolving environmental regulations and sustainability goals. That consolidation can simplify qualification matrices, reduce stocking burdens across global projects, and lower the risk of installing “the right size, wrong polymer” during outages.

The boundaries are important: above the stated temperature range, alternative elastomer families may be more appropriate; and for certain hydrocarbon-rich or highly specialised chemical environments, another polymer may outperform EPM.

The right approach is disciplined validation: define the actual media (including impurities), pressure/temperature envelope, decompression profile, and required certifications, then test the candidate compound in representative conditions.

A Practical Checklist to Specify EPM for H₂ and CCUS Valves

• Define the real fluid. Is it an amine blend? Dense-phase CO₂? Dry H₂? What water content and impurities are expected across normal operation and upset cases?
• Define the pressure-cycle story. What is the maximum pressure, and how fast can depressurisation occur during trips, blowdowns, or maintenance?
• Match the temperature envelope. Consider both steady-state and transient cooling/heating, including Joule–Thomson effects and cold ambient starts.
• Ask for compound-level validation. “EPM” is a family; request data for the specific compound: immersion results (volume/hardness/tensile retention), compression set, and any relevant aging tests.
• Include RGD screening when appropriate. Use a recognised method and specify gas, temperature, soak pressure, and decompression rate that reflect the service.
• Don’t ignore mechanics. Confirm hardness and extrusion resistance match the gland design; ensure tolerances and surface finishes support the chosen elastomer.
• Verify regulatory and project requirements. Depending on location and service, you may need additional documentation for emissions, safety, or material compliance.

A Near “One-Fits-All” Elastomer Platform? It’s Possible When You Keep the Temperature in Check

H₂ and CCUS projects are often evaluated through the lens of megatons and gigawatts, but their credibility is also built on operational discipline: tight systems, low leakage, and equipment that lasts. Valve seals are small components with outsized influence on those outcomes.

EPM is not a magic material, and it will not replace every polymer in every valve. But as an elastomer family, it can credibly satisfy a wide variety of the needs that dominate sustainability valve service – chemical resistance in many polar media (including common capture chemistries), strong low-temperature sealing behaviour, and the ability (with the right compound design) to perform well under CO₂/H₂ pressure cycling and RGD risk.

For projects operating below roughly 150°C, that combination makes EPM a compelling candidate for material standardisation, and a practical lever for improving reliability and reducing the lifecycle footprint of the equipment that makes low-carbon infrastructure work.

FAQs

What are EPM elastomers?

EPM elastomers are ethylene propylene rubber materials without a diene component. They are widely used for industrial sealing because they offer excellent resistance to many polar chemicals low-temperature flexibility and long service life.

Why are EPM elastomers suitable for hydrogen and CCUS valves?

EPM elastomers combine chemical compatibility with many capture solvents strong resistance to rapid gas decompression and reliable sealing under pressure cycling making them well suited to hydrogen and carbon capture applications.

What causes seal failures in hydrogen and CCUS systems?

The most common causes include chemical attack low-temperature embrittlement rapid gas decompression excessive pressure cycling and exposure to aggressive process media.

What is rapid gas decompression (RGD)?

Rapid gas decompression occurs when gas absorbed into an elastomer expands faster than it can escape during depressurisation causing internal cracking blistering or seal failure.

How do EPM elastomers compare with FKM and HNBR?

Each material has strengths depending on the application. EPM generally offers an excellent balance of chemical resistance low-temperature performance and gas decompression resistance while FKM provides higher temperature capability and HNBR offers good mechanical strength.

Can one elastomer be used across an entire hydrogen or CCUS project?

While no elastomer is suitable for every application EPM can often cover a broad range of hydrogen and CCUS valve duties below approximately 150°C reducing material complexity and inventory requirements.

What should engineers consider when selecting an elastomer for hydrogen valves?

Engineers should evaluate process media operating temperatures pressure cycles decompression rates regulatory requirements and compound-specific performance data rather than selecting materials by polymer family alone.

How can better seal materials improve sustainability?

Longer-lasting seals reduce maintenance minimise fugitive emissions lower material consumption decrease downtime and extend equipment life helping improve the overall sustainability of hydrogen and CCUS infrastructure.