Why hydrogen facility HVAC is different from any other industrial HVAC project
Of every industrial vertical we have supplied ductwork to since 1995 — petrochemical, pharmaceutical, semiconductor cleanrooms, mining ventilation, lithium battery gigafactories — green hydrogen production is the most demanding combination of explosion risk, materials sensitivity, code overlap and project schedule pressure that we encounter. The HVAC system on a hydrogen plant is not a back-of-house service. It is a primary safety-critical layer of protection that sits between a credible hydrogen leak and a confined-space deflagration. Get it wrong and the plant cannot be commissioned, the operator's safety case will not be approved, and the project sits idle on the critical path while electrolyser stacks gather dust.
The fundamental physics is hostile. Hydrogen has a lower flammable limit of 4 percent by volume in air and an upper flammable limit of approximately 75 percent — a flammable range four times wider than methane and ten times wider than petrol vapour. Its minimum ignition energy is 0.017 millijoules, roughly one tenth of methane and far below the static spark from a synthetic-fibre work shirt. Its molecular size lets it leak through joints and seal materials that contain natural gas without issue. Its flame is nearly invisible in daylight and emits very little radiant heat to skin, so an undetected hydrogen flame can stand on a flange face for minutes before anyone notices. And its relative density of 0.0695 means a leak rises straight to the ceiling void — exactly the location where engineers have, for decades, been comfortable hiding HVAC trunk runs and electrical conduit.
Because the consequences of error are so severe, the international code framework around hydrogen plant HVAC is dense, overlapping and under continuous revision. In Australia, the relevant standards are AS/NZS 60079.10.1 for area classification, AS/NZS 60079.14 for installation, AS/NZS 60079.17 for inspection, AS/NZS 1715 for mechanical ventilation in hazardous atmospheres, AS 4254 for sheet metal duct construction, and AS/NZS 1668 for ventilation system performance. In Europe the matching set is the ATEX Directive 2014/34/EU, the EN 60079 series, and EN 1505 / EN 1506 for ductwork. In North America the framework is the National Electrical Code Article 500 with Class I Division 1 and Division 2 zoning, NFPA 2 for hydrogen technologies, and SMACNA for duct construction. ISO 19880 covers hydrogen fuelling station design as a global standard. The IRENA and IEA Hydrogen Council reports cover commercial and policy context but not engineering specification.
This guide walks through the hydrogen-specific design considerations a plant engineer, ATEX consultant or HVAC contractor needs to specify ductwork correctly on a green hydrogen project. It is written from a practitioner's standpoint — what the design engineer actually has to decide, what materials and certifications matter, how the global project pipeline is shaping the supply chain, and where SBKJ machinery fits into a hydrogen project's HVAC fabrication strategy. It is not a substitute for project-specific safety analysis or for the relevant national standards, both of which always take precedence.
Hydrogen production technologies and their HVAC implications
The first input to any HVAC specification is which hydrogen production technology the plant uses, because each technology has different temperatures, pressures, materials and leak characteristics that drive the surrounding building services design. Four electrolyser technologies dominate the green hydrogen pipeline today.
Alkaline electrolysis (KOH)
Alkaline electrolysis is the oldest and currently the cheapest electrolyser technology, with cell stacks operating at 60 to 90 degrees Celsius in a 25 to 30 percent potassium hydroxide solution. The dominant HVAC consequence is alkaline carryover — fine droplets of KOH solution entrained in the hydrogen and oxygen gas streams leaving the cell stacks. This carryover is corrosive to galvanized steel, mild steel and aluminium, which is why the entire electrolyser hall typically specifies 316L stainless ductwork rather than the galvanized steel that dominates conventional commercial HVAC. Alkaline cell stacks operate at 1 to 30 bar gauge pressure, which is low by industrial standards but still drives compressor capacity downstream. The hydrogen leakage rate from alkaline stacks is typically 0.1 to 1 percent of production, so a 100 megawatt alkaline plant producing 1,800 kilograms per hour of hydrogen has a credible diffuse leak rate of 1.8 to 18 kilograms per hour distributed across the hall — the dominant ventilation sizing case.
Polymer Electrolyte Membrane (PEM) electrolysis
PEM electrolysers use a solid polymer membrane (Nafion or equivalent) as the electrolyte, with cell stacks operating at 50 to 80 degrees Celsius and 10 to 50 bar gauge. PEM stacks are dimensionally smaller and accept faster load transients than alkaline, which makes them attractive for variable renewable input, and the absence of liquid alkaline electrolyte means less corrosive carryover. However, PEM stacks operate at higher pressure than most alkaline designs, which means a higher specific leakage risk per joint and a stronger jet velocity if a leak occurs. PEM electrolyser halls in our experience use 316L stainless ductwork by default but can sometimes specify 304 stainless if alkaline ammonia exposure is fully eliminated from adjacent areas. Cell stack temperatures are slightly cooler than alkaline, but the stacks are heat-dense, so the HVAC system has to remove 8 to 12 percent of input electrical power as waste heat from the stack room.
Solid Oxide Electrolysis Cell (SOEC)
SOEC technology operates at 700 to 850 degrees Celsius using a ceramic electrolyte (typically yttria-stabilised zirconia). The cell stack itself sits inside an insulated hot box, but the surrounding electrolyser hall must handle significant heat rejection — a 10 megawatt SOEC plant can reject 1.5 to 2 megawatts of waste heat to the room, which is a heavy summer cooling load. SOEC plants typically use heat recovery ductwork to recover this waste heat for steam generation feeding the cell stacks, which in turn changes the duct material specification. The recovery duct between the cell stack hot box outlet and the steam generator inlet operates at 200 to 500 degrees Celsius and must be specified in 309 or 310 stainless or in a high-temperature alloy such as Inconel 625 — well outside the SBAL-V auto duct line capability and into hand-fabrication territory. SOEC plants are still mostly demonstration scale (a few megawatts to 100 megawatts) but the project pipeline is growing rapidly.
Anion Exchange Membrane (AEM) electrolysis
AEM is the newest of the four technologies, combining the polymer membrane format of PEM with the alkaline chemistry of conventional KOH systems. Cell stacks operate at 50 to 70 degrees Celsius and 1 to 35 bar gauge with a dilute potassium hydroxide circulating electrolyte. AEM is being commercialised by several European and US developers, with the first commercial-scale AEM plants entering operation in 2025 and 2026. From an HVAC standpoint, AEM behaves close to a hybrid of alkaline and PEM — alkaline-grade material specification (316L stainless throughout) but lower carryover than full alkaline because the dilute electrolyte is easier to retain in the gas-liquid separator. Project teams should treat AEM as alkaline for HVAC sizing until vendor data shows otherwise.
Electrolyser building HVAC — the core design problem
The electrolyser hall is where the bulk of the HVAC ductwork goes on a green hydrogen project, and where the consequences of getting design wrong are most severe. Three engineering problems dominate.
Mechanical room ventilation rate
The starting point is dilution ventilation. AS/NZS 1715 and IEC 60079-10-1 both require continuous mechanical ventilation that maintains hydrogen concentration below 25 percent of the LFL (1 percent by volume) under worst-case credible leak conditions. In practice this works out to 6 to 12 air changes per hour for a typical electrolyser hall, depending on cell stack density and ceiling height. For a 100 megawatt electrolyser plant occupying a 5,000 square metre hall with a 12 metre ceiling, total ventilation rate is typically 60,000 to 120,000 cubic metres per hour of supply air and an equal volume of exhaust air. The exhaust air system is 10 to 20 percent oversized relative to supply to maintain a slight negative pressure inside the hall — so any hydrogen leak migrates inward (where it is detected and exhausted) rather than outward into surrounding spaces.
Hydrogen leak detection — sensor spacing and setpoints
Hydrogen leak detection is the second engineering pillar. IECEx-certified hydrogen detectors (typically catalytic bead, electrochemical or thermal conductivity sensors) are installed at ceiling level on a maximum 10 metre by 10 metre grid, with additional detectors at high-risk release points (around stack manifolds, gas-liquid separator vents, sample points). First-stage alarm setpoint is 10 percent LFL (0.4 percent hydrogen by volume) which triggers ventilation boost from normal to high-flow mode. Second-stage alarm at 25 percent LFL (1 percent by volume) triggers full plant evacuation, electrolyser stack trip and emergency blowdown to vent stacks. The detection system is independent of the HVAC control system but interlocked with it, so a detector trip overrides any HVAC manual mode and forces the system to high-flow exhaust.
Forced exhaust at the highest ceiling point
The third engineering pillar is exhaust placement. Because hydrogen rises rapidly (relative density 0.0695), the exhaust intake must be at the highest point of the ceiling — within 300 millimetres of the apex on a pitched roof, and never above structural beams or trusses that could trap a hydrogen pocket. SBKJ ductwork on hydrogen projects routinely runs across the ceiling void in 316L stainless rectangular trunk with multiple drop-in branches collecting from every roof bay. Branch take-offs are sized for a face velocity of 8 to 10 metres per second on collection and the trunk runs at 12 to 15 metres per second to keep cross-section compact. Pressure loss budget is typically 200 to 300 pascal across the entire exhaust system to keep fan power within ESD generator backup capacity.
ATEX, IECEx and North American hazardous area classification
The hazardous area classification drawing is the master document that drives every HVAC equipment specification on a hydrogen project. Three regional frameworks dominate.
ATEX (Europe) and IECEx (international)
The ATEX Directive 2014/34/EU is mandatory for any equipment placed on the EU market for use in explosive atmospheres. The IECEx scheme is the international equivalent run by the IEC, and certificates issued under IECEx are accepted in Australia, the Middle East, much of Asia and increasingly in North America for owner-operator equipment. Both schemes use the Zone classification system: Zone 0 for atmospheres present continuously or for long periods, Zone 1 for atmospheres likely in normal operation, Zone 2 for atmospheres unlikely in normal operation and present only for short periods. Equipment is marked with a gas group (IIA for propane, IIB for ethylene, IIC for hydrogen and acetylene), a temperature class (T1 to T6, where T1 is up to 450 degrees Celsius surface temperature), and an equipment protection level (Ga for Zone 0, Gb for Zone 1, Gc for Zone 2). Hydrogen is gas group IIC — the most demanding category — and any HVAC equipment installed in a Zone 1 or Zone 2 hydrogen area must carry IIC certification. T1 temperature class is acceptable because hydrogen autoignition temperature is 500 degrees Celsius.
Australia and New Zealand — AS/NZS 60079 series
Australia adopts the IEC 60079 series under the AS/NZS 60079 dual-numbered standards. The principal documents for HVAC engineers are AS/NZS 60079.10.1 (area classification for explosive gas atmospheres), AS/NZS 60079.14 (electrical installations design), AS/NZS 60079.17 (inspection and maintenance), and AS/NZS 60079.19 (equipment repair and overhaul). Equipment certified under IECEx is accepted in Australia by the SAA (Standards Australia Approval) scheme administered by IECEx Australia. Project teams in Australia should retain a Certified Hazardous Area Auditor under the IECEx CoPC scheme to sign off the area classification drawing and the as-built installation. The IECEx auditor is typically engaged at FEED stage, before any HVAC equipment specification is locked.
North America — NEC Article 500 / 502 / 503
The US National Electrical Code (NFPA 70) Article 500 uses a Class / Division system rather than Zones. Class I covers flammable gases and vapours (Class II is dust, Class III is fibres). Division 1 corresponds approximately to Zone 0 plus Zone 1; Division 2 corresponds to Zone 2. Article 501 covers Class I locations specifically, Article 502 covers Class II, Article 503 covers Class III. Equipment is marked with an NEC group (Group A for acetylene, Group B for hydrogen, Group C for ethylene, Group D for propane) and a temperature code (T1 to T6 matching IECEx). Hydrogen is NEC Group B. North American projects are increasingly accepting IECEx-certified equipment under the NEC Article 505 zone-classified provisions, which mirrors the IECEx zone framework. Owner operators in the US Gulf Coast hydrogen pipeline (Air Products, Plug Power, Hy Stor) are commonly specifying dual NEC and IECEx certification on imported HVAC equipment to avoid re-certification disputes during construction.
Practical impact on HVAC equipment selection
The downstream impact for HVAC ductwork specification is concentrated in the active equipment, not the passive ductwork itself. Sheet metal duct is not Ex-rated equipment under any framework — it is treated as part of the building envelope. However, every device installed on or in the duct that could be a source of ignition must carry the appropriate Ex marking: fan motors (IECEx Ex de IIC T4 typical), volume control dampers with electric actuators, fire and smoke dampers with thermal links, hydrogen sensors, pressure differential transmitters, and any control panel mounted in the zoned area. The sheet metal duct itself is bonded to the plant earth grid to dissipate any electrostatic charge, with maximum continuity resistance of 1 megohm between any two points. SBKJ supplies HVAC ductwork without integral electrical equipment, so the Ex certification burden falls on the active devices fitted by the HVAC contractor at site rather than on the duct fabricator.
Compressor and gas conditioning building HVAC
Downstream of the electrolyser hall, hydrogen is compressed from electrolyser outlet pressure (1 to 50 bar) to storage or distribution pressure (typically 30 to 700 bar, depending on end use). Hydrogen compressors generate substantial waste heat from gas compression — a typical 20 megawatt hydrogen compressor station rejects 4 to 5 megawatts of heat to the surrounding building, much of it via radiant heat from the compressor cylinder heads, motor windings and intercooler skids. This drives a compressor building HVAC specification that prioritises heat removal alongside the standard hazardous area requirements.
Typical compressor building HVAC design uses a high-flow displacement ventilation strategy: cool fresh air is supplied at low level around the compressor skids at 4 to 6 metres per second face velocity through floor-mounted grilles, and warm air is exhausted at high level through ceiling-mounted exhaust grilles. The supply-to-exhaust differential maintains the building at slight negative pressure to contain any hydrogen leak. Total air change rate is typically 15 to 20 per hour during normal operation, rising to 25 to 30 per hour on hydrogen detector first-stage alarm. Building cooling load is typically 200 to 500 watts per square metre of floor area, depending on compressor density and insulation effectiveness on the compressor packages.
The control room is normally physically separated from the compressor hall by a fire-rated wall and pressurised independently. Control room HVAC is a positive-pressure refuge — supply air at 50 to 100 pascal above the surrounding compressor hall, with no air return path from the compressor hall back to the control room. The control room fresh air intake is typically located on the building exterior 20 metres or more from any hydrogen vent stack, with hydrogen monitoring on the intake duct. If the intake monitor detects hydrogen above 10 percent LFL, the control room HVAC switches to recirculation mode and isolates from the outside air supply until the contamination clears.
Storage and dispensing area HVAC
Hydrogen storage and dispensing typically operates at 350 bar (Type 3 cylinders or tube trailers) for heavy mobility applications and 700 bar (Type 4 carbon-fibre composite cylinders) for passenger vehicle refuelling. Storage areas can be open-air bunds, partially covered canopies, or fully enclosed rooms depending on local code. From an HVAC standpoint, partially covered canopies and enclosed rooms drive the specification.
Refuelling station canopies under ISO 19880-1
ISO 19880-1 covers gaseous hydrogen fuelling stations and is the global standard for refuelling site design. The standard requires the canopy to provide either natural ventilation through open sides (minimum 50 percent of canopy perimeter open or louvred) or mechanical ventilation sized to maintain less than 25 percent LFL under worst-case credible leak. Hydrogen leak detection is required at canopy peak with first alarm at 10 percent LFL and second alarm at 25 percent LFL. The dispenser itself is Zone 1 within 1 metre and Zone 2 within 3 metres of any release point; the refuelling vehicle parking position is Zone 2 during refuelling and unclassified at other times. HVAC ductwork on refuelling station canopies is typically minimal — the canopy roof is open or louvred and natural ventilation dominates — but where mechanical ventilation is required, 316L or 304 stainless steel duct rated to AS 4254 is the standard specification.
Tube trailer storage compounds
Hydrogen tube trailer storage compounds (350 bar typical) are usually open-air with chain-link fencing on three sides and a fire-rated wall on the fourth side. There is rarely any ductwork on tube trailer storage areas because the open-air environment provides sufficient natural ventilation. The exception is enclosed tube storage buildings used in cold climate sites — Northern Europe, Eastern Canada, Northern Japan — where freezing rain or snow accumulation on outdoor storage drives an enclosed design. Enclosed tube storage requires forced ventilation at 6 to 12 air changes per hour with hydrogen detection equivalent to the electrolyser hall standard.
High-pressure dispenser islands
Heavy-duty refuelling dispensers (700 bar for transit buses and class 8 trucks) often sit on dispenser islands with overhead canopies. The dispenser island is Zone 1 for 1 metre and Zone 2 for 3 metres in all directions during refuelling. Canopy ventilation on the island typically combines natural ventilation through the open sides with mechanical exhaust at the canopy peak above each dispenser. Stainless or aluminium ductwork is preferred for corrosion resistance from the marine atmosphere on coastal sites.
Liquid hydrogen (LH2) facility HVAC — cryogenic plant building
Liquid hydrogen is increasingly important for long-distance hydrogen transport and for aerospace applications, with several large-scale LH2 export facilities at FEED or FID stage. LH2 introduces three additional HVAC engineering challenges on top of gaseous hydrogen.
Cold box room ventilation
The LH2 cold box operates at minus 253 degrees Celsius and is heavily insulated, but the cold box outer enclosure surfaces operate at a low temperature relative to the surrounding building. Any moist air contacting the cold box outer surfaces will condense water vapour, which can in turn freeze and accumulate as ice. More dangerously, oxygen has a boiling point of minus 183 degrees Celsius and nitrogen has a boiling point of minus 196 degrees Celsius, so any cold surface below 183 degrees Celsius can condense liquid oxygen from the surrounding air — creating an oxygen-enriched atmosphere on the cold box outer surfaces. This is a credible fire hazard if any combustible material (lubricant film, plastic insulation, even certain gasket materials) is present near the cold surface.
Cold box HVAC specification therefore requires continuous ventilation of the cold box room at 6 to 10 air changes per hour to maintain low relative humidity (typically below 40 percent) and to dilute any oxygen enrichment. Oxygen monitors are installed at floor level (because oxygen-enriched air is denser than ambient air) with first alarm at 23 percent oxygen and second alarm at 25 percent oxygen. The cold box room HVAC system runs on a dedicated supply and exhaust duct system independent of the surrounding compressor and electrolyser building services.
BLEVE risk and fire-rated separation
Liquid hydrogen storage tanks present a Boiling Liquid Expanding Vapour Explosion (BLEVE) risk in fire scenarios — if a fire impinges on the tank shell, internal pressure rises rapidly and the tank can rupture with catastrophic consequences. Code separation distances between the LH2 storage tank and any occupied building are 30 to 50 metres typical (project-specific per QRA). HVAC fresh air intakes for adjacent buildings must be located on the side facing away from the LH2 tank, with hydrogen monitoring on the intake to detect any vapour cloud migration.
Pressure relief and vent stack routing
LH2 tank pressure relief valves discharge cold hydrogen vapour through a dedicated cold vent stack. The vent stack must be elevated above any adjacent building roofs (typically 5 to 10 metres above the highest occupied roof within 50 metres) and located so that a hydrogen vapour plume disperses to less than 25 percent LFL before reaching any HVAC fresh air intake or ignition source. Routing the cold vent stack through any HVAC ductwork is prohibited — the cold gas would freeze any moisture in the duct, and the hydrogen-air mixture inside the duct would create an internal Zone 0 environment.
Green ammonia synthesis from hydrogen — additional HVAC requirements
Ammonia synthesis (Haber-Bosch process) downstream of the electrolyser is the dominant hydrogen export pathway under development globally — large-scale green ammonia projects are at FEED in Australia, Saudi Arabia, Oman and Mauritania. Adding ammonia synthesis to a hydrogen project layers a toxic-gas hazard on top of the existing flammable-gas hazard.
Ammonia toxicity and exposure limits
Anhydrous ammonia is toxic at low concentrations: the ACGIH TLV-TWA is 25 ppm (8-hour time-weighted average) and the STEL is 35 ppm (15-minute short-term exposure limit). Acute exposure above 300 ppm causes severe respiratory damage; concentrations above 2,500 ppm are immediately dangerous to life and health. Ammonia is also flammable in air at concentrations between 15 and 28 percent by volume, although the toxicity exposure limit is reached long before the flammability limit in any credible release scenario.
Ammonia gas detection
Ammonia detection in a synthesis loop building uses electrochemical sensors with first alarm at 25 ppm (TLV-TWA) and second alarm at 35 ppm (STEL). Sensor placement is at breathing height (1.5 metres above floor) because ammonia is similar in density to air and does not strongly stratify. Detector spacing is typically 8 to 10 metres centre-to-centre, with additional detectors at known release points (compressor seals, sample points, valve stems). The detection system interlocks with the synthesis loop emergency shutdown to isolate the converter and depressurise to flare.
Material restrictions in ammonia areas
Ammonia attacks copper, brass, bronze and zinc rapidly, forming soluble copper-ammine complexes that destroy copper-bearing components within hours of exposure. Ammonia plant HVAC specifications therefore eliminate copper from the airstream entirely: motor windings must be aluminium-wound or specified with ammonia-resistant copper coatings, refrigeration coils must be all-aluminium or stainless tube construction, control valves must be aluminium-bronze-free, and any flexible duct connectors must be free of brass or zinc plating. Ductwork is 316L stainless throughout, with stainless or aluminium fan impellers and aluminium grilles.
Synthesis loop building zoning
The synthesis loop building combines a Zone 2 hydrogen classification (from the syngas mix of hydrogen and nitrogen) with a separate toxic-gas zone for ammonia. The two zoning frameworks operate in parallel: hydrogen-rated equipment for ignition control, ammonia-rated equipment for toxic-gas exposure control. HVAC ductwork specification is dual-rated — 316L stainless serves both requirements without compromise.
Materials selection — why 316L dominates hydrogen plant ductwork
The single most important materials decision on a hydrogen project is the duct steel grade. Three considerations drive the selection.
Hydrogen embrittlement of carbon and high-strength steels
Hydrogen embrittlement is a phenomenon where hydrogen atoms diffuse into the metal lattice and reduce ductility, leading to brittle failure under stress. The risk is concentrated at hydrogen partial pressures above approximately 100 bar and on high-strength low-alloy steels (typically yield strength above 700 megapascals). HVAC ductwork operates at low pressure (a few hundred pascal) and uses low-strength sheet metal (yield strength 200 to 350 megapascals on commercial sheet), so direct embrittlement of the duct material is not the dominant concern. However, ductwork in close proximity to high-pressure hydrogen pipework, or downstream of a vent stack discharging high-pressure hydrogen, can experience locally elevated hydrogen partial pressure during a leak event. Specifying austenitic stainless steel (304 or 316L) eliminates embrittlement concerns because austenitic structures are not susceptible.
Alkaline corrosion from electrolyser carryover
The dominant materials threat on alkaline electrolyser projects is alkaline corrosion. Fine droplets of 25 to 30 percent KOH solution carried over from the cell stacks impinge on the duct internal surface, where the moisture eventually evaporates leaving a concentrated potassium hydroxide deposit. This deposit attacks galvanized steel rapidly (within months), attacks aluminium within a year, and eventually attacks carbon steel as well. 316L stainless steel resists alkaline attack effectively at the temperatures involved (up to 80 degrees Celsius continuous), with corrosion rates below 0.05 millimetres per year — negligible over a 25-year plant life.
Cleanability and weld quality
The third consideration is fabrication and inspection. 316L is the dominant grade for welded stainless ductwork because it offers low carbon content (below 0.03 percent) which suppresses chromium carbide precipitation in the heat-affected zone during welding. This in turn prevents inter-granular corrosion at the weld joint. 304L is acceptable for non-corrosive service but 316L provides additional margin for marginal alkaline carryover or chloride contamination from coastal site air. SBKJ recommends 316L for any duct downstream of an alkaline electrolyser cell stack and 304 for non-process areas (control room, workshop, office HVAC).
Copper, brass and bronze restrictions
For any project that includes ammonia synthesis (green ammonia), copper-bearing materials are eliminated from the airstream. This extends to motor windings, refrigeration coil tubes, control valve internals, flexible duct connector wires, and any decorative or architectural finish. Specifying aluminium-wound motors and stainless or aluminium coils adds 15 to 25 percent to the equipment cost but is non-negotiable in ammonia plant specifications.
Pressure relief and vent stack ductwork
Pressure relief and vent stack systems are not strictly HVAC, but they share a fabrication shop with HVAC ductwork on most projects and the same SBKJ machinery is often used to fabricate both. Three vent stack categories appear on hydrogen projects.
Cell stack continuous vents
Electrolyser cell stacks have continuous vent connections for nitrogen purging during maintenance and for low-rate hydrogen bleed during normal operation. Continuous vents typically operate at 1 to 5 bar gauge and discharge through a small-diameter (DN50 to DN150) header to a central vent stack. Stainless ductwork on continuous vents is fabricated from 316L coil on the SBKJ SBTF spiral tubeformer for the round header sections, with hand-fabricated transitions and elbows on the connections to individual cell stacks.
Pressure relief valve discharge
Pressure relief valves protect compressors, separators, storage vessels and pipework. The PRV discharge piping is normally hard pipe rather than HVAC duct (because it operates at high pressure) but where a low-pressure PRV discharge connects into a flare header, the connecting duct may be HVAC-grade stainless. Sizing follows API 521 rather than HVAC standards.
Emergency blowdown vents
Emergency blowdown systems depressurise the electrolyser cell stacks, compressor packages and storage vessels in a runaway scenario. Blowdown rates can be 100 kilograms per hour or more of hydrogen, discharging through a dedicated blowdown header to an elevated vent stack. Blowdown headers are normally hard pipe; the dispersion of the discharged hydrogen plume is modelled to confirm that it dilutes below 25 percent LFL before reaching any building HVAC fresh air intake within 50 metres.
Flare stack ventilation
Some larger hydrogen projects (particularly green ammonia plants) include a flare stack to combust off-spec hydrogen during start-up, shutdown or upset conditions. The flare structure itself does not contain HVAC ductwork, but the building services at the flare base — pilot gas skid, ignition controller, knock-out drum maintenance access — require local ventilation in the surrounding zoned areas.
Australian green hydrogen project pipeline
Australia is currently the largest concentration of green hydrogen project development globally, driven by abundant solar and wind resource in Western Australia and Queensland and by federal incentive programmes including Hydrogen Headstart and the Hydrogen Production Tax Incentive (HPTI). The Australian Government Hydrogen Headstart programme allocates AUD 2 billion of federal funding to bridge the cost gap between green hydrogen production cost and grey hydrogen, with the first round announced in 2023 and the second round under evaluation in 2026.
Asian Renewable Energy Hub (Pilbara, WA)
The Asian Renewable Energy Hub in the East Pilbara region of Western Australia targets 26 gigawatts of installed wind and solar capacity feeding electrolysers producing green hydrogen and green ammonia for export to Asian markets. The project is led by InterContinental Energy, CWP Global, Vestas and Pathway Investments. The project area covers 6,500 square kilometres of pastoral land and is currently in environmental approval and FEED phases. HVAC ductwork demand at full build-out is in the tens of thousands of linear metres of 316L stainless rectangular duct and several thousand linear metres of stainless spiral round duct, distributed across electrolyser halls, compressor stations, ammonia synthesis loops and ammonia storage buildings.
Western Green Energy Hub (Goldfields, WA)
The Western Green Energy Hub is a 50 gigawatt renewable energy and green hydrogen project in the southern Goldfields region of Western Australia, led by Intercontinental Energy, CWP Global and Mirning Green Energy Limited. The project area covers approximately 15,000 square kilometres and targets first-phase operations in the early 2030s. The HVAC scope at full build is comparable to the Asian Renewable Energy Hub.
Murchison Hydrogen Renewables (Mid West, WA)
The Murchison Hydrogen Renewables project, led by Copenhagen Infrastructure Partners and Murchison Hydrogen Renewables Pty Ltd, targets 5,000 megawatts of renewable energy with 2,500 megawatts of electrolyser capacity producing green ammonia for export through Geraldton or Oakajee Port in Western Australia.
Stanwell Central Queensland Hydrogen Hub (CQ-H2)
The CQ-H2 project, led by Stanwell Corporation with Iwatani Corporation, Marubeni and Keppel as joint venture partners, targets 720 megawatts of electrolyser capacity at Aldoga industrial precinct near Gladstone in Central Queensland. First-phase production is targeted for the late 2020s with liquid hydrogen export to Japan as the primary off-take. CQ-H2 received Hydrogen Headstart funding in the first allocation round.
Origin Hunter Valley Hydrogen Hub
Origin Energy's Hunter Valley Hydrogen Hub at Kooragang Island in New South Wales is a smaller-scale early-development project targeting up to 55 megawatts of electrolyser capacity feeding industrial off-takers in the Hunter Valley region. The project sits on existing industrial land with established services and is on a faster schedule than the export-scale projects, with first hydrogen targeted for 2027.
Hydrogen Headstart and HPTI policy framework
The Hydrogen Headstart programme provides production-linked subsidy support, while the Hydrogen Production Tax Incentive (HPTI) announced in the 2024 Australian Federal Budget provides AUD 2 per kilogram of green hydrogen produced for ten years on projects reaching FID before 2030. The two policies together substantially improve project economics and have driven a wave of FEED activity through 2025 and into 2026.
European green hydrogen project pipeline
The European Union's REPowerEU strategy targets 10 million tonnes per year of domestic green hydrogen production and 10 million tonnes of green hydrogen imports by 2030. Several large-scale European projects are at FEED, FID or early construction.
Iberdrola / Cepsa Spain
Iberdrola is developing multiple electrolyser projects across the Iberian peninsula, including the 200 megawatt Puertollano green hydrogen plant which entered operation in 2022 and a 1 gigawatt project pipeline through 2030. Cepsa, in partnership with several Spanish utilities, is targeting 2 gigawatts of green hydrogen capacity at Huelva and Algeciras for export to northern Europe.
Air Liquide Normandy
Air Liquide is constructing a 200 megawatt PEM electrolyser plant at Port-Jerome in Normandy, France, for industrial hydrogen supply to the surrounding refining and petrochemical complex. The project uses Siemens Energy electrolyser technology and is targeted for commissioning in 2026.
Lhyfe France
Lhyfe operates and develops a fleet of small-to-mid scale (1 to 100 megawatt) green hydrogen plants across France and Germany, primarily targeting industrial off-takers and mobility refuelling. The Bouin pilot plant in western France was the first European offshore-coupled green hydrogen production facility.
Aurubis Hamburg
Aurubis, the German copper smelter, is integrating green hydrogen into its Hamburg refining operations as a substitute for natural gas in metal recovery processes. The project includes a 60 megawatt PEM electrolyser tied to renewable PPAs, with hydrogen supply by pipeline within the Hamburg port industrial estate.
Hyporta Brunsbuettel and Topsoe Denmark
The Hyporta project at Brunsbuettel in northern Germany targets up to 700 megawatts of green hydrogen capacity for export to industrial off-takers in the Hamburg-Bremen industrial corridor. Topsoe in Denmark is commercialising SOEC technology with the first commercial-scale unit at the Herning facility, targeting export to European steel and refining customers.
North American green hydrogen project pipeline
The US Inflation Reduction Act (IRA) Section 45V provides a production tax credit of up to USD 3 per kilogram of green hydrogen for ten years, which has unlocked a substantial project pipeline across the US Gulf Coast, Midwest and Northeast.
Plug Power Genesee, NY
Plug Power's Genesee facility in upstate New York is one of the first US green hydrogen plants in continuous commercial operation, with 45 megawatts of PEM electrolyser capacity feeding regional industrial and mobility customers. Plug operates several similar-scale facilities across the US.
Air Products Louisiana blue hydrogen
Air Products is constructing a USD 4.5 billion blue hydrogen complex at Ascension Parish, Louisiana, integrating natural gas reforming with carbon capture and sequestration to produce 750 million standard cubic feet per day of blue hydrogen. While not green hydrogen, the HVAC scope and hazardous area design is comparable.
Hy Stor Mississippi Clean Hydrogen Hub
Hy Stor Energy is developing a 110,000 acre green hydrogen production and salt cavern storage facility in Mississippi, targeting 2 gigawatts of green hydrogen production and large-scale geological storage for off-take to Gulf Coast industrial customers.
Cummins-Iberdrola Spain joint venture
Cummins and Iberdrola formed a joint venture to manufacture PEM electrolysers in Castile-La Mancha Spain, supplying European and global green hydrogen projects. Cummins separately owns the Accelera (formerly Hydrogenics) electrolyser technology platform.
Middle East green hydrogen project pipeline
The Middle East combines abundant renewable resource (solar particularly) with established hydrocarbon export infrastructure that can be re-purposed for hydrogen and ammonia export. Several flagship projects are under construction or at FEED.
NEOM Helios green hydrogen (Saudi Arabia)
The NEOM Helios project in northwest Saudi Arabia is the largest green hydrogen project under construction globally — a USD 8.4 billion joint venture between NEOM, ACWA Power and Air Products, targeting 600 tonnes per day of green hydrogen production from 4 gigawatts of solar and wind, converted to 1.2 million tonnes per year of green ammonia for export. The project is in construction with first ammonia export targeted for 2026 to 2027. HVAC scope is at the largest end of any global project.
Masdar / Mubadala Abu Dhabi
Masdar (the Mubadala renewable energy subsidiary) is developing multiple green hydrogen and ammonia projects across the UAE and in partnership with international developers in Egypt, Mauritania, Morocco and Australia. The Abu Dhabi domestic project pipeline targets 1 gigawatt of green hydrogen production by the late 2020s.
Oman Hyport Duqm and Salalah
Oman has positioned the Duqm and Salalah special economic zones as green hydrogen export hubs, with multiple projects at FEED including the OQ8 / Marubeni / Linde green ammonia project at Salalah and the Hyport Duqm project led by DEME, OQ and Uniper.
Japan and South Korea green hydrogen ecosystem
Japan and South Korea are the dominant import markets for green hydrogen and ammonia, with significant domestic project development on the import-receiving and end-use side, plus joint ventures upstream into Australian and Middle Eastern production projects.
Eneos Yokohama
Eneos operates the Yokohama refinery hydrogen import terminal as one of Japan's first commercial green hydrogen import receiving facilities, with onward distribution to industrial and mobility customers in the Tokyo metropolitan area. ENEOS H2 is the dedicated hydrogen subsidiary developing import infrastructure across Japan.
Mitsubishi Heavy Industries
Mitsubishi Heavy Industries supplies hydrogen-fired gas turbines, ammonia co-firing combustion systems for coal power stations, and hydrogen storage and transport technology. MHI is a participant in several Australian and Middle Eastern green hydrogen and ammonia export projects.
Korea Zinc, POSCO and Hyundai
Korea Zinc has committed to ammonia-based renewable energy supply for its zinc smelting operations, sourcing green ammonia from Australian and Middle Eastern suppliers. POSCO is developing hydrogen-based steelmaking (HyREX) at the Pohang and Gwangyang steel works, with green hydrogen supply from international partners. Hyundai Motor Group operates one of the largest fuel cell vehicle programmes globally and is developing domestic hydrogen refuelling infrastructure to support the Nexo and XCIENT vehicle platforms.
International standards and reference framework
Several international bodies publish standards and guidance directly relevant to hydrogen plant HVAC design.
IRENA and IEA Hydrogen Council reports
The International Renewable Energy Agency (IRENA) publishes annual reports on green hydrogen cost trajectories, technology benchmarking and market outlook. The IEA Hydrogen Council publishes a similar annual report covering global project pipeline and policy frameworks. Both reports are useful for project teams sizing equipment to industry-typical references but neither contains direct engineering specification.
ISO 19880 hydrogen fuelling station series
The ISO 19880 series covers gaseous hydrogen fuelling stations (Part 1 General requirements, Part 3 Valves, Part 5 Dispensers, Part 8 Fuel quality control). Part 1 is the master standard for fuelling station HVAC and ventilation design and is referenced in most national codes including AS/NZS, EN and NFPA equivalents.
ISO 22734 water electrolyser standard
ISO 22734 covers industrial water electrolysers — the cell stack and balance of plant — with safety requirements that drive electrolyser building HVAC design indirectly. The standard is referenced by most major electrolyser vendors as part of their packaged plant scope.
Sustainable Aviation Fuel (SAF) integration with hydrogen plants
SAF (Sustainable Aviation Fuel) production is an increasingly common downstream off-take for green hydrogen, particularly via the Power-to-Liquids pathway combining green hydrogen with captured carbon dioxide to produce synthetic kerosene. The relevant aviation specifications are ASTM D7566 (SAF blends) and the ICAO CORSIA framework. From an HVAC standpoint, SAF synthesis adds a Fischer-Tropsch reactor block downstream of the electrolyser and a hydrogenation upgrade unit to convert intermediates to drop-in jet fuel. The synthesis reactor block operates at elevated temperature (200 to 350 degrees Celsius) and pressure (20 to 50 bar gauge) with hazardous area zoning equivalent to a refinery hydrocracker. Ductwork specification carries over from hydrogen plant practice — 316L stainless throughout, IECEx-rated active equipment, dilution ventilation sized to credible leak rate.
Construction phase HVAC challenges
Hydrogen plant construction generates substantial hot-work activity — pipe welding, structural steel welding, mechanical fitting, instrument calibration — with significant fume and welding spatter generation. Permanent HVAC ductwork is typically installed in the latter phases of construction, meaning the building services during the bulk of welding work are temporary ventilation systems.
Temporary ventilation typically uses portable diesel-fired air movers and flexible polyethylene duct routed to local welding zones. Air change rates are typically 4 to 8 per hour during welding activity, dropping to 2 per hour during non-active periods. Hydrogen detection is usually not commissioned during construction (because there is no hydrogen present), but oxygen-deficiency monitoring may be required for confined-space welding.
Permanent HVAC commissioning typically runs in parallel with mechanical completion of the cell stacks and compressor packages. The HVAC system is hot-commissioned (run for 30 to 60 days at design operating conditions) before any hydrogen is admitted to the cell stacks. This sequencing protects the operating personnel during initial start-up — a credible failure on first hydrogen introduction is much more likely than during steady-state operation, and the HVAC system needs to be fully proven before first hydrogen.
Permanent HVAC system architecture
Pulling the design considerations together, a typical green hydrogen plant has five distinct HVAC zones, each with its own duct material, ventilation rate, control philosophy and detection package.
Electrolyser hall
Continuous mechanical ventilation at 6 to 12 air changes per hour, slight negative pressure relative to surroundings, exhaust at ceiling apex, hydrogen detection at ceiling on a 10 metre by 10 metre grid, 316L stainless rectangular and spiral duct throughout. Fan motors IECEx Ex de IIC T4. Volume control and fire dampers IECEx-rated where installed in zoned areas.
Compressor and gas conditioning hall
Higher ventilation rate (15 to 20 ACH) to handle compressor heat rejection, displacement strategy with low-level supply and high-level exhaust, hydrogen detection plus thermal monitoring on compressor packages. 316L stainless ductwork standard. Slight negative pressure relative to control room.
Control room (positive-pressure refuge)
Pressurised at 50 to 100 pascal above the surrounding compressor and electrolyser halls. Fresh air intake from outside the plant battery limits with hydrogen monitoring on the intake duct. Filtered supply air through HEPA or G4 filters depending on outdoor air quality. 304 stainless or galvanized duct acceptable inside the control room (no process exposure).
Cryogenic plant (LH2)
Dedicated supply and exhaust at 6 to 10 air changes per hour, oxygen monitoring at floor level, low relative humidity maintenance, separation from adjacent buildings to manage BLEVE risk. 316L stainless ductwork throughout.
Maintenance workshop
Low-rate ventilation (2 to 6 ACH), hot-work permit system for any welding or grinding inside the building. Galvanized or 304 stainless duct acceptable; the workshop is normally outside the zoned areas of the plant.
SBKJ machinery for green hydrogen projects
SBKJ supplies HVAC ductwork fabrication machinery to hydrogen and ammonia plant fabricators across Australia, Europe, the Middle East and Asia. The most common machine specifications on hydrogen projects are:
SBAL-V auto duct line — stainless configuration
The SBAL-V auto duct production line in stainless configuration accepts 316L coil up to 1.5 millimetres thick and produces TDF flange rectangular ductwork from 200 millimetres wide up to 1,500 millimetres wide. The stainless configuration includes hardened tooling with extended life on stainless coil, stainless-compatible coolant and lubricant systems, and brushed stainless rolls to minimise surface marking. Output is approximately 8 to 12 linear metres per minute on 1 millimetre 316L coil. The standard SBAL-V control panel is non-Ex (the machine sits in a fabrication shop, not in a zoned plant area), but SBKJ supplies an ATEX Zone 2 panel option for fabrication shops integrated into the main plant battery limits.
SBTF stainless spiral tubeformer
The SBTF spiral tubeformer in stainless configuration produces 316L spiral round ductwork from 100 millimetres diameter up to 1,500 millimetres diameter, in continuous lengths up to the available coil width permits. The SBTF is the machine of choice for vent stack header runs, exhaust trunk runs and any large-diameter circular duct on hydrogen projects. Forming speed on 1 millimetre 316L coil is approximately 6 to 10 metres per minute.
Welding and finishing equipment
Stainless ductwork on hydrogen projects normally requires continuously welded longitudinal seams (Pittsburgh seams are not permitted in Zone 1 areas under most plant licensor specifications). SBKJ supplies GTAW (TIG) seam welders and plasma seam welders as add-on equipment to the SBAL-V and SBTF lines. Surface finishing equipment includes pickle-and-passivation lines for post-weld surface restoration on 316L.
Quality and traceability
Hydrogen plant fabricators normally require mill certificates on every coil and weld procedure qualification records on every welder. SBKJ machines support material traceability through coil tag readers and weld parameter logging at the PLC. The standard SBKJ FAT procedure (see the HVAC duct machine buyer's checklist) is extended to include stainless-specific qualification on hydrogen projects, with witness inspection by the buyer's QA representative.
How SBKJ specifies HVAC ductwork on a hydrogen project
The procedure SBKJ engineers walk through with hydrogen project fabricators looks like the following sequence, which has evolved from supplying machinery to dozens of hazardous area projects across hydrogen, ammonia, LNG and petrochemical sectors over the last decade.
- Read the hazardous area classification drawing. The HAC drawing is the master document. Every duct segment is annotated with its zone classification (Zone 0, 1, 2 or unclassified) and gas group (IIC for hydrogen). The HAC drawing comes from the plant licensor or independent ATEX consultant — never improvised by the HVAC contractor.
- Read the electrolyser package datasheet. The electrolyser vendor's datasheet specifies cell stack temperature, pressure, hydrogen leakage rate, oxygen leakage rate, and recommended ventilation rate around the package skid. SBKJ ductwork sizing follows the vendor data unless the plant licensor specifies tighter requirements.
- Confirm the ammonia or downstream synthesis scope. If green ammonia or SAF synthesis is downstream, the materials specification extends across the whole plant — copper-free motors, all-aluminium coils, dual-rated detection. SBKJ confirms this at quotation stage to size the coil order correctly.
- Size the duct cross-section to face velocity. 8 to 10 metres per second on supply collection, 12 to 15 metres per second on exhaust. Cross-section sized for 200 to 300 pascal total pressure loss across the system. Duct sized to standard SBAL-V outputs (200 mm to 1,500 mm wide rectangular, plus stainless spiral round on the SBTF for trunk runs).
- Specify the connection method. TDF flange standard for rectangular duct on the SBAL-V; bolted slip-fit for round duct on the SBTF. Continuous longitudinal seam welding for any Zone 1 or Zone 0 duct; standard mechanical seam acceptable for Zone 2 and unclassified duct.
- Confirm coil source. 316L stainless coil from European or Asian mills — SBKJ does not specify the coil mill but does specify coil grade, thickness and surface finish. Mill certificates required for every coil.
- Schedule fabrication. Stainless duct fabrication on the SBAL-V at 8 to 12 metres per minute output translates to 50 to 70 metres of finished duct per shift after handling and inspection. A typical 100 megawatt electrolyser hall requires 2,000 to 4,000 linear metres of duct, fabricated in 30 to 60 shifts.
- Test and commission. Pressure test installed ductwork to 1.5 times design operating pressure. SMACNA or AS 4254 leakage class A standard. Witness test by buyer or independent inspector. Document on commissioning report tied to the hazardous area register.
This procedure runs parallel to the electrolyser package commissioning and is normally on the project critical path during the ten months before first hydrogen.
Cost benchmarks and lead time
Hydrogen plant HVAC ductwork costs are dominated by the stainless coil price and welding labour, both of which run at substantial premium to commercial galvanized work.
Material cost benchmarks
316L stainless coil at 1 millimetre thickness costs approximately 4 to 6 times equivalent galvanized coil per kilogram, depending on mill source and order volume. Total finished duct cost (material plus fabrication labour plus welding) typically runs 3 to 5 times equivalent galvanized commercial work per linear metre. A 1,500 mm wide by 600 mm deep 316L stainless rectangular duct typically lands at AUD 600 to 900 per linear metre installed, against AUD 150 to 250 per linear metre for the equivalent galvanized.
Lead time benchmarks
Stainless coil lead time from European or Asian mills is currently 10 to 16 weeks for 316L in HVAC-typical thicknesses (0.7 to 1.5 millimetres). Fabrication on the SBAL-V or SBTF runs at 8 to 12 metres per minute output, so a typical 3,000 metre electrolyser hall scope fabricates in 6 to 8 weeks of single-shift operation. Field installation typically runs 1 to 2 metres per metalworker-hour for stainless duct (against 3 to 5 metres for galvanized) due to welding and finishing requirements. End-to-end from purchase order to installed and commissioned duct system is typically 6 to 9 months on a hydrogen project, against 3 to 5 months on equivalent commercial work.
SBKJ machine delivery lead time
The SBAL-V and SBTF are typically delivered within 16 to 22 weeks of order from the SBKJ project office, including stainless tooling configuration and FAT. See the HVAC duct machine buyer's checklist for full procurement guidance.
Comparison with adjacent industry HVAC scopes
Hydrogen plant HVAC sits at the demanding end of industrial HVAC scope and shares many design considerations with adjacent industries. Mining ventilation and battery gigafactory HVAC are two of the closer adjacent scopes.
Mining ventilation, particularly underground hard rock mining, shares the dilution ventilation philosophy with hydrogen plants — keep target gas concentration below a defined threshold by air dilution. The threshold is different (typically 0.5 percent methane in coal mines, less than 30 ppm carbon monoxide in metal mines, against 1 percent hydrogen in electrolyser halls), and the materials specification is different (galvanized or low-carbon steel acceptable in mines, 316L stainless required in hydrogen plants). The fan, damper and detection technology overlaps substantially. See the mining ventilation HVAC duct guide for the comparable scope.
Battery gigafactory HVAC shares the cleanroom-grade contamination control (lithium-ion cells are extremely sensitive to humidity and trace contaminants) with semiconductor and pharmaceutical work, plus the lithium fire and thermal runaway hazard which drives a fire-resistant duct specification. See the battery gigafactory HVAC duct guide for the comparable scope. Battery and hydrogen plants share the materials sensitivity (stainless throughout) but differ on the fire and explosion philosophy — hydrogen drives dilution ventilation, batteries drive zoned containment.
For the underlying material decision between galvanized and stainless on industrial duct, see the galvanized versus stainless steel duct comparison guide. Hydrogen plant HVAC is one of the few scopes where 316L stainless is mandatory rather than optional.
Inspection, maintenance and operational compliance
Once commissioned, a hydrogen plant HVAC system enters a structured inspection and maintenance regime under AS/NZS 60079.17 (or the equivalent EN 60079-17 in Europe). Three inspection levels are defined.
Visual inspection (every 12 months)
Visual inspection covers external condition of duct, fan housings, dampers and detection equipment. Inspection is performed by qualified personnel without disassembly. Findings logged in the plant hazardous area register.
Close inspection (every 24 months)
Close inspection includes external visual plus measurement of clearances, external sealing surfaces, damper actuator function, gas detector calibration. No internal disassembly required.
Detailed inspection (condition-based)
Detailed inspection includes internal disassembly, cleaning and re-certification of equipment showing degradation. Required when visual or close inspection identifies a non-conformance.
The plant operator is required to retain a Certified Hazardous Area Auditor under the IECEx CoPC or equivalent national scheme to oversee the inspection regime and to sign off any modifications to the HVAC or hazardous area arrangement. Modifications without competent inspector sign-off are a regulatory non-conformance and a credible audit finding.
Frequently Asked Questions
What is the lower flammable limit of hydrogen and why does it drive HVAC design?
Hydrogen has an LFL of 4 percent by volume in air and an UFL of approximately 75 percent — the widest flammable range of any common industrial gas. Combined with a minimum ignition energy of 0.017 millijoules and a near-invisible flame, hydrogen demands HVAC designs that prevent any pocket reaching even 25 percent of the LFL (1 percent by volume). Electrolyser rooms, compressor halls and dispensing canopies must have continuous mechanical ventilation, hydrogen leak detection at ceiling level and forced exhaust capable of clearing the room volume in minutes.
What hazardous area zones apply to a hydrogen electrolyser building under ATEX/IECEx?
A typical alkaline or PEM electrolyser room is Zone 2 in normal operation, with localised Zone 1 around stack manifolds, gas-liquid separators and vent stacks. Cell stack interiors are Zone 0. AS/NZS 60079.10.1 and IEC 60079.10.1 govern allocation; the North American framework is NEC Article 500 with Class I Division 1 and Division 2. HVAC equipment in zoned areas must carry Ex marking with gas group IIC and temperature class T1.
Why is 316L stainless preferred over carbon steel for hydrogen ductwork?
The dominant driver is alkaline corrosion from KOH carryover off alkaline electrolyser stacks, which attacks galvanized steel within months. Hydrogen embrittlement is a secondary consideration — the duct itself runs at low pressure, but elevated hydrogen partial pressure during a leak event can affect carbon steel. 316L resists both alkaline attack and embrittlement, with corrosion rates below 0.05 millimetres per year over the 25-year plant life.
What ventilation rate does an electrolyser room require?
AS/NZS 1715, IEC 60079-10-1 and most plant licensors require 6 to 12 air changes per hour, sized to dilute worst-case credible hydrogen leak below 25 percent of LFL. For a 100 MW electrolyser hall, that is 60,000 to 120,000 cubic metres per hour of supply and exhaust air, with exhaust intake at the highest ceiling point because hydrogen rises rapidly.
Are SBKJ machines suitable for fabricating hazardous-area HVAC ductwork?
Yes. The SBAL-V auto duct line and SBTF spiral tubeformer accept 316L and 304 stainless coil up to 1.5 mm thick — the standard material for hydrogen, ammonia and cryogenic plant HVAC. SBKJ supplies ATEX-rated control panels as an option, although the typical configuration is non-Ex machinery in a separate fabrication shop with finished ductwork shipped to the zoned plant.
What is the difference between NEMA and IP ratings for HVAC equipment in hydrogen plants?
NEMA ratings are used in North America; IP ratings under IEC 60529 are used in Australia, Europe and Asia. Typical electrolyser-area HVAC fan motor specification is IP66 minimum, equivalent to NEMA 4X. For Ex-rated equipment, IECEx and ATEX certificates take precedence over IP rating because Ex certification covers explosion protection while IP covers dust and water ingress only.
How does a green ammonia plant differ from a hydrogen-only plant for HVAC?
Green ammonia adds a Haber-Bosch synthesis loop with toxic ammonia exposure on top of hydrogen flammability risk. Ammonia TLV-TWA is 25 ppm, and ammonia attacks copper, brass and bronze rapidly. The synthesis building requires ammonia gas detection, 316L stainless duct throughout, and zero copper in the airstream including motor windings and refrigeration coils.
What is the typical lead time for stainless HVAC ductwork on a hydrogen project?
For a fabrication shop running an SBAL-V auto duct line with 316L stainless coil, finished duct is delivered to site within 8 to 14 weeks of stainless coil arrival. Coil lead time from European or Asian mills is currently 10 to 16 weeks for 316L. Project teams should plan 6 to 9 months from electrolyser package PO to ductwork installation start.
How SBKJ supports hydrogen project HVAC fabricators
SBKJ Group operates from Box Hill North, Victoria, Australia, with project engineering, technical support and after-sales service for HVAC ductwork machinery on hydrogen, ammonia, mining and battery projects across the Asia-Pacific, Europe and the Middle East. Our standard project engagement on a green hydrogen fabrication scope includes:
- Technical specification review against the project's hazardous area classification drawing, electrolyser package datasheet and downstream synthesis scope.
- Machine specification for the stainless SBAL-V auto duct line and SBTF spiral tubeformer with optional ATEX control panels.
- Coil specification support for 316L stainless from European or Asian mill sources, including mill certificate handling and traceability through fabrication.
- Welding equipment supply including GTAW seam welders and plasma cutters for stainless seam continuous welding.
- Factory Acceptance Test at the SBKJ project office with witness inspection by the buyer or third-party QA representative.
- Installation supervision and operator training at the buyer's fabrication shop, with multi-language trainers covering English and other major project languages.
- After-sales support through the Box Hill North office, with 12-hour response on technical queries from a senior mechanical engineer.
Talk to an SBKJ engineer about your hydrogen project HVAC scope →
