Why hydrogen-and-ammonia HVAC is the hardest brief on an Australian engineer's desk
Of every industrial vertical we engage with from the Box Hill North office, the green-hydrogen and downstream ammonia, methanol and liquid-hydrogen carrier scope is the most demanding combination of explosion risk, toxic gas exposure, materials sensitivity, code overlap and project schedule pressure that an Australian mechanical engineer is asked to navigate. The HVAC system is not a back-of-house service inside an electrolyser hall. It is a primary safety-critical layer of protection that sits between a credible hydrogen leak and a confined-space deflagration. Get the ductwork wrong and the plant cannot be commissioned, the operator's safety case is not approvable by SafeWork or the WHS regulator, and the entire project sits idle on the critical path while imported electrolyser stacks sit in their crates on the laydown yard accruing demurrage.
The fundamental physics is hostile. Hydrogen has a lower explosive limit (LEL) of 4 percent by volume in air and an upper explosive 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 well below the static spark from a synthetic-fibre high-vis shirt or a poorly bonded earthed worker. Its molecular size lets it leak through joints and elastomer seals 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 (air = 1) means a leak rises straight to the ceiling void — exactly the location where Australian commercial HVAC engineers have, for decades, been entirely comfortable routing trunk runs, plenum returns and electrical conduit.
Layer ammonia on top, and the Safe Work Australia hydrogen LEL conversation moves into a parallel toxic-gas conversation with workplace exposure standards of 25 ppm 8-hour time-weighted average and 35 ppm 15-minute short-term exposure. Layer liquid hydrogen on top of that and you add cryogenic oxygen condensation, BLEVE risk and the broadly counter-intuitive observation that released LH2 vapour starts denser than air before warming and rising. Layer 350-and-700-bar refuelling on top of that and you add jet release dispersion, dispenser zone overlay and ISO 19880-1 specifically. The HVAC engineer reading this guide is asked to deliver a single system that handles all of the above under the AS/NZS 60079 series adopted verbatim from IEC, the AS 1668.2 mechanical ventilation code, AS 4254 ductwork construction, AS 1530.4 fire-rated penetrations, AS 4332 gas storage, AS 4564 gas supply, AS 4647 and AS 4646 gas equipment, AS 1851 fire damper maintenance, AS 1657 access platforms, with international cross-reference to ISO 19880, ISO 26142, ISO 14687, NFPA 2, NFPA 55, NFPA 70 NEC Article 500 and the ATEX Directive 2014/34/EU for any imported European-spec equipment.
This guide walks through what an Australian consulting engineer, IECEx CoPC hazardous area auditor, mechanical contractor or process owner has to decide when specifying HVAC ductwork for a green-hydrogen project under Hydrogen Headstart, the Hydrogen Production Tax Incentive (HPTI) and the Australian Hydrogen Council Standards Strategy framework. It is written from the practitioner's standpoint — what the design engineer actually has to decide, which materials and certifications matter, where the SBKJ machine fleet (SBAL-V auto duct line, SBTF spiral tubeformer, SBSF-1525 stitchwelder and SBPC1500 plasma cutter) lands inside a 316L stainless fabrication scope, and how the current wave of Australian projects under Fortescue, Stanwell, Woodside, Origin, AGL, ATCO and Hysata is shaping the local supply chain. It is not a substitute for project-specific safety analysis, the relevant national standards or the signed-off hazardous area classification drawing — all of which always take precedence.
Hydrogen production technologies and their HVAC consequences
The first input to any HVAC specification is which hydrogen production technology the project has selected, because each technology has different cell-stack temperature, operating pressure, liquid-electrolyte chemistry and gas leakage profile that drives the surrounding building services design. Four electrolyser technologies dominate the Australian project pipeline, with a fifth (capillary-fed alkaline from Hysata) emerging from local R&D.
Alkaline electrolysis (AEL)
Alkaline electrolysis is the oldest and currently the cheapest electrolyser technology, with cell stacks operating at 60-90 degrees C in a 25-30 percent KOH or NaOH circulating electrolyte. Stack pressure is typically 1-30 bar gauge — low by industrial standards but still drives compressor capacity downstream. The dominant HVAC consequence is alkaline carryover — fine droplets of KOH solution entrained in the hydrogen and oxygen gas streams leaving the cell stacks. The Safe Work Australia caustic mist WES is 2 mg/m3 ceiling, and this carryover is corrosive to galvanised steel, aluminium and unprotected mild steel. The entire electrolyser hall typically specifies 316L stainless ductwork throughout. Alkaline cell hydrogen leakage rate is typically 0.1-1 percent of production, so a 100 MW alkaline plant producing 1,800 kg/h of H2 has a credible diffuse leak rate of 1.8-18 kg/h 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 50-80 degrees C and 10-50 bar gauge. PEM stacks are dimensionally smaller and accept faster load transients than alkaline, which makes them attractive for variable renewable input — a critical consideration on the Western Australian solar-plus-wind hybrid sites where renewable input swings by tens of percent within minutes. Absence of liquid alkaline electrolyte means less corrosive carryover, but PEM stacks operate at higher pressure than most alkaline designs, which means higher jet velocity per leak event and stronger near-source ventilation demand. PEM is the chosen technology at Origin Bell Bay TAS, AGL Hydrogen Park Murray Valley Mildura, Air Liquide Australia industrial supply and several of the smaller Fortescue and ATCO sites. Cell stack temperatures are slightly cooler than alkaline, but stacks are heat-dense — the HVAC system has to remove 8-12 percent of input electrical power as waste heat. PEM stack deconditioning (an end-of-life process) can release trace sulphuric acid mist from the perfluorosulphonic acid membrane breakdown; Safe Work Australia WES for sulphuric acid mist is 1 mg/m3.
Anion Exchange Membrane (AEM) electrolysis
AEM is the newest of the four mainstream technologies, combining the polymer membrane format of PEM with the alkaline chemistry of conventional KOH systems. Cell stacks operate at 50-70 degrees C and 1-35 bar gauge with a dilute potassium hydroxide circulating electrolyte. AEM is being commercialised by Enapter, Sunfire and several European developers, with the first commercial-scale AEM plants entering operation in 2025-2026. 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 in Australia should treat AEM as alkaline for HVAC sizing until vendor data shows otherwise.
Solid Oxide Electrolysis Cell (SOEC)
SOEC technology operates at 700-850 degrees C using a ceramic electrolyte (typically yttria-stabilised zirconia, YSZ). The cell stack itself sits inside an insulated hot box, but the surrounding electrolyser hall must handle significant heat rejection — a 10 MW SOEC plant rejects 1.5-2 MW of waste heat to the room. 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 on the recovery section. The recovery duct between the hot box outlet and the steam generator inlet operates at 200-500 degrees C 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 MW) but the project pipeline is growing — Topsoe is the primary global vendor and several Australian operators are evaluating SOEC for high-temperature steam-coupled service.
Capillary-fed alkaline (Hysata)
Hysata, a Wollongong-based UNSW spinout, is commercialising a capillary-fed alkaline electrolyser that targets system efficiency above 95 percent (compared to the 70-80 percent achievable on conventional alkaline). The technology removes most of the gas-liquid separation problem by routing electrolyte and gas through a wicking layer inside the cell stack itself, dramatically reducing carryover. From an HVAC standpoint, Hysata's process drawings suggest the stack-room ventilation rate can drop below the conventional 6-12 ACH because the leak profile is lower per kilowatt of installed capacity. SBKJ has been in early-stage contact with the Hysata supply chain on stainless duct fabrication and we expect the first commercial-scale Hysata projects to drive an Australian-specific specification baseline distinct from European AEL imports.
Electrolyser hall 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. Four engineering problems dominate.
Mechanical room dilution ventilation
The starting point is dilution ventilation. AS/NZS 1715 and AS/NZS 60079.10.1 (adopting IEC 60079-10-1 verbatim) both require continuous mechanical ventilation that maintains hydrogen concentration below 25 percent of the LEL (1 percent by volume, 10,000 ppm) under worst-case credible leak conditions. In practice this works out to 6-12 air changes per hour for a typical electrolyser hall, depending on cell stack density, ceiling height and the leak profile in the licensor's vendor data pack. For a 100 MW electrolyser plant occupying a 5,000-7,000 square metre hall with a 12 metre ceiling, total ventilation rate is typically 60,000-150,000 cubic metres per hour of supply air and an equal or slightly higher exhaust to maintain a small negative pressure inside the hall relative to surrounding clean areas. The negative pressure containment ensures any hydrogen leak migrates inward (where it is detected and exhausted) rather than outward into corridors, switchrooms or the control room.
Hydrogen leak detection grid under ISO 26142
Hydrogen leak detection is the second engineering pillar. ISO 26142-certified hydrogen detectors (typically catalytic bead, electrochemical or metal-oxide-semiconductor 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, pipe rack penetrations and switch-room fresh-air intakes. First alarm setpoint at 25 percent of LEL = 1 percent hydrogen by volume triggers ventilation boost from normal to high-flow mode, audible-visual alarm and an operator notification to the central control room. Second alarm at 50 percent of LEL = 2 percent hydrogen triggers electrolyser stack emergency shutdown ESD, emergency blowdown to vent stacks, full plant evacuation alarm and switching of the control room HVAC to recirculation mode. The detection system is independent of the building management system BMS but interlocked with HVAC controls so a detector trip overrides any manual mode and forces high-flow exhaust. Sensor calibration is on a 6-month cycle with full functional testing on each calibration; records are filed in the plant hazardous area register.
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 mm of the apex on a pitched roof, and never above structural beams or roof 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 8-10 m/s on collection and the trunk runs at 12-15 m/s to keep cross-section compact. Pressure loss budget is typically 200-300 Pa across the entire exhaust system to keep fan power within ESD generator backup capacity. For very tall halls (above 15 metres ceiling), the CFD dispersion model often shows hydrogen pocketing under purlins or rafters; the response is additional branch take-offs at every rafter bay rather than a sparser, larger trunk.
Negative pressure cascade to control room
The fourth pillar is the pressure cascade. The electrolyser hall is held at slight negative pressure (10-25 Pa) relative to surrounding corridors, switchrooms and the control room. The control room itself is at positive pressure 50-100 Pa above ambient, isolated from the electrolyser hall by a vapour-tight wall and a personnel airlock. On detector trip, the cascade is reinforced — the electrolyser hall exhaust ramps to high-flow mode, drawing the hall to a deeper negative; the control room supply continues at design, maintaining its positive pressure and protecting personnel inside. Pressure differential transmitters at every airlock are interlocked to AHU control. Cascade verification during commissioning is mandatory with all doors closed and again under worst-case door-open scenarios.
AS/NZS 60079 hazardous area classification — the master document
The hazardous area classification (HAC) drawing is the master document that drives every HVAC equipment specification on a hydrogen project. Three regional frameworks dominate; in Australia the IEC-derived AS/NZS 60079 series is mandatory.
AS/NZS 60079 series in Australia
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 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. The Standards Australia ME-093 technical committee chairs ongoing standards revision and is the official conduit for industry comment on AS/NZS 60079 updates.
ATEX Directive 2014/34/EU (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. 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 — the most demanding), a temperature class (T1 to T6, where T1 is up to 450 degrees C surface temperature), and an equipment protection level (Ga for Zone 0, Gb for Zone 1, Gc for Zone 2). Hydrogen is gas group IIC; temperature class T1 is acceptable because hydrogen autoignition is 500 degrees C. Imported European-spec equipment carries ATEX marking and is acceptable in Australia under the cross-recognition between ATEX and IECEx.
NFPA 2 hydrogen technologies and NFPA 55 compressed gases (North America cross-reference)
Some Australian projects financed under US lender criteria — particularly those with Inflation Reduction Act IRA Section 45V production tax credit linkage, or those exporting under DOE-financed off-take arrangements — must also demonstrate compliance with NFPA 2 hydrogen technologies code and NFPA 55 compressed gases and cryogenic fluids code. NFPA 2 covers separation distances, ventilation requirements and explosion protection across the full hydrogen value chain — production, storage, distribution and dispensing. NFPA 55 covers compressed gas systems generally with hydrogen-specific clauses. The two NFPA standards are largely consistent with the AS/NZS 60079 framework, but separation distances differ in detail and the auditor must reconcile both. NFPA 70 (the US National Electrical Code) Article 500 with Class I Division 1/2 zoning is referenced where US-spec equipment is being procured; Article 505 mirrors the IECEx zone framework and is the easier integration path.
Practical impact on HVAC equipment selection
The downstream impact for HVAC ductwork 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 IP66 typical), volume control dampers with electric actuators, fire and smoke dampers with thermal links, hydrogen sensors, smoke detectors, 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. Spark-resistant fan impellers in aluminium or non-sparking stainless are standard. SBKJ supplies the duct fabrication line and the duct itself; active electrical equipment is sourced ATEX/IECEx-rated by the HVAC contractor and installed at site, with the certification burden falling on the active devices rather than the duct fabricator.
Compressor and gas conditioning hall HVAC
Downstream of the electrolyser hall, hydrogen is compressed from electrolyser outlet pressure (1-50 bar) to storage or distribution pressure (typically 200-700 bar). Hydrogen compressors generate substantial waste heat — a typical 20 MW hydrogen compressor station rejects 4-5 MW of heat to the surrounding building, much of it as radiant heat from compressor cylinder heads, motor windings and intercooler skids. This drives a compressor building HVAC specification that prioritises heat removal alongside hazardous area requirements.
Typical compressor hall HVAC uses a displacement ventilation strategy: cool fresh air is supplied at low level around the compressor skids at 4-6 m/s face velocity through floor-mounted grilles, and warm air is exhausted at high level through ceiling-mounted exhaust grilles. The supply-to-exhaust offset maintains the building at slight negative pressure to contain any hydrogen leak. Total air change rate is typically 15-20 per hour during normal operation, rising to 25-30 per hour on a first-stage hydrogen detector alarm. Building cooling load is 200-500 W/m2 of floor area, depending on compressor density and the insulation effectiveness on individual compressor packages. The compressor packages themselves are ATEX-rated IIC at the vendor's package boundary; the HVAC supply and exhaust ductwork sits outside the package envelope.
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 50-100 Pa 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 25 percent LEL, the control room HVAC switches to recirculation mode and isolates from the outside air supply until the contamination clears. Backup oxygen monitoring at floor level inside the control room (because oxygen-enriched air is denser than ambient air) covers the secondary hazard of cold LH2 cargo migrating from an adjacent cryogenic plant.
Hydrogen refuelling station HRS HVAC under ISO 19880
Hydrogen refuelling stations are an increasingly visible part of the Australian hydrogen landscape, with public-facing sites at Fortescue Williamtown NSW, Coregas Sydney, Hydrogen Park Murray Valley Mildura VIC, ATCO Jandakot WA and a growing portfolio under the HyDrive ARENA-funded program. The vehicle off-takers include the Toyota Mirai fleet in Sydney and Melbourne, the Hyundai NEXO fleet in Canberra and select interstate routes, the BMW iX5 hydrogen fleet on demonstration, and growing class 8 truck and transit bus operators.
Dispenser island zoning under AS/NZS 60079
ISO 19880-1 is the global standard for gaseous hydrogen fuelling station design and is the primary reference in Australia, cross-referenced with the AS/NZS 60079 series for hazardous area classification specifically. The dispenser itself is Zone 1 within 1 metre of any release source (nozzle, hose connection, breakaway coupling) and Zone 2 within 3 metres in all directions during refuelling. The refuelling vehicle parking position is Zone 2 during refuelling and unclassified at other times. The compressor and storage skid behind the dispenser is Zone 2 in its enclosure, with localised Zone 1 around stack vents. The fill panel for tube trailer change-out is Zone 2 during connection and disconnection.
Canopy ventilation strategy
ISO 19880-1 allows two ventilation strategies for the dispenser canopy. Strategy 1 is natural ventilation through an open or louvred canopy perimeter on at least 50 percent of the canopy face area, with the canopy roof pitched or peaked to allow hydrogen to escape upward. Strategy 2 is mechanical ventilation sized to maintain less than 25 percent LEL under worst-case credible leak. Australian sites overwhelmingly use Strategy 1 because the cost and complexity of mechanical canopy ventilation, combined with the salt-spray exposure on coastal sites, makes natural ventilation the more reliable option. The canopy is typically a structural-steel column-and-rafter portal with mesh louvre wall infill, peaked roof in Colorbond and a translucent skylight strip along the apex. Hydrogen detection at canopy peak is ISO 26142-certified, alarm at 25 percent LEL with refuelling cut-off interlock to the dispenser nozzle solenoid.
Compressor and storage skid ventilation
The enclosed compressor and storage skid behind the dispenser does require mechanical ventilation. Typical design is 12-20 ACH with low-level supply and high-level exhaust, in displacement ventilation mode. Duct is 316L stainless on any run inside the Zone 2 envelope and aluminium-clad insulated 304L on the cooling supply trunks. The skid enclosure is typically a portable shipping-container-style unit factory-built and shipped to site as a packaged solution, with the HVAC ductwork integrated at the vendor's factory rather than fabricated locally. SBKJ has supplied stainless duct components on factory-built compressor skids for several Australian and international HRS vendors.
Pressure ratings — 350 bar versus 700 bar
Heavy mobility refuelling (transit bus, class 8 truck, refuse collection vehicle) typically uses 350 bar (35 MPa) nominal storage pressure with Type 3 composite cylinders. Passenger vehicle refuelling uses 700 bar (70 MPa) with Type 4 composite cylinders. The 700 bar specification adds significant compressor capacity (a 700 bar dispenser needs an inlet pressure of approximately 920 bar to deliver a fast fill) and increases jet release velocity per leak event. From an HVAC standpoint, the 700 bar dispenser drives slightly higher ventilation rates at the canopy (more headroom on worst-case LEL exceedance) and a deeper Zone 2 envelope around the dispenser. Most Australian HRS sites operate both pressures in parallel — Fortescue Williamtown and Coregas Sydney both have 350 and 700 bar dispensers under one canopy.
Liquid hydrogen LH2 facility HVAC — cryogenic plant building
Liquid hydrogen is increasingly important for long-distance hydrogen transport and the Stanwell CQ-H2 project in Central Queensland with Iwatani as off-taker is the flagship LH2 export project under the Hydrogen Headstart program. LH2 introduces three additional HVAC engineering challenges on top of gaseous hydrogen.
Cold box room ventilation and oxygen condensation
The LH2 cold box operates at -253 degrees C using a Claude or Brayton refrigeration cycle, heavily insulated with vacuum-jacketed pipework. The cold box outer enclosure surfaces operate at low temperature relative to the surrounding building. Any moist air contacting these surfaces will condense water vapour, which can in turn freeze and accumulate as ice. More dangerously, oxygen has a boiling point of -183 degrees C and nitrogen of -196 degrees C, so any cold surface below -183 degrees C 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, certain gasket materials) is present near the cold surface.
Cold box HVAC specification therefore requires continuous ventilation of the cold box room at 6-10 ACH 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 the Safe Work Australia 19.5 percent lower limit and 23.5 percent upper limit setpoints, plus a hard upper alarm at 25 percent oxygen. The cold box room HVAC runs on a dedicated supply and exhaust duct system independent of the surrounding compressor and electrolyser building services.
Cold LH2 vapour displacement behaviour
Released LH2 vapour behaves counter-intuitively at the source. Initial vapour temperature is at or below -253 degrees C, and at that temperature gaseous hydrogen is denser than ambient air at 22 degrees C. The released cloud initially sinks toward floor level, displacing ambient air, before warming to roughly -22 degrees C at which point it becomes buoyant and rises. Conventional ceiling-only exhaust strategy is therefore insufficient near LH2 release sources — displacement ventilation with both low-level intake and high-level exhaust is preferred for the LH2 building specifically, with low-level intake at the floor perimeter capturing the initial dense vapour and high-level exhaust capturing the post-warming buoyant phase.
BLEVE risk and fire-rated separation
Liquid hydrogen storage dewar vessels 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 catastrophically. Project-specific QRA typically lands separation distances of 30-50 metres between the LH2 storage tank and any occupied building. 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 valves PRV on LH2 tanks discharge through a dedicated cold vent stack routed up and away from any HVAC fresh air intake or ignition source.
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 in Australia — Bell Bay TAS (Origin and Mitsui), Port Hedland WA (multiple proponents), Gladstone QLD and Geraldton mid-west are all at FEED or EPC with green ammonia as the carrier of choice. The active Australian ammonia operators (currently grey or blue, transitioning to green) include Yara Pilbara Fertilisers at Karratha WA, Orica Yarwun in Gladstone QLD, CSBP Kwinana in WA (the Wesfarmers Chemicals Energy and Fertilisers WesCEF subsidiary), Incitec Pivot Phosphate Hill, Gibson Island and Moranbah QLD. Adding ammonia synthesis layers a toxic-gas hazard on top of the hydrogen flammable-gas hazard.
Ammonia toxicity and exposure limits
Anhydrous ammonia is toxic at low concentrations: the Safe Work Australia WES is 25 ppm 8-hour TWA and 35 ppm STEL (15-minute short-term exposure). Acute exposure above 300 ppm causes severe respiratory damage; concentrations above 2,500 ppm are immediately dangerous to life and health (IDLH). 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. Inside the ammonia synthesis loop building the design driver is therefore the WES exceedance trip, not the LEL exceedance trip.
Ammonia gas detection
Ammonia detection in a synthesis loop building uses electrochemical sensors with first alarm at 25 ppm (TLV-TWA equivalent) 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 (molecular weight 17 against 29 for air) and does not strongly stratify. Detector spacing is typically 8-10 metres centre-to-centre, with additional detectors at known release points (compressor seals, sample points, valve stems, sniff points around flange faces). 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. The cost uplift is 15-25 percent on the affected equipment but is non-negotiable.
Ammonia loading and unloading manifolds
Rail and road loading and unloading manifolds at the ammonia synthesis plant battery limit are Zone 1 hazardous around connections during transfer per AS/NZS 60079. Each manifold is fitted with an emergency depressurisation system venting to an NH3 scrubber stack, which in turn discharges through a caustic neutralisation column before atmospheric vent. The scrubber stack itself is FRP (fibre-reinforced polyester with vinyl ester resin) for the caustic exposure surface, transitioning to 316L stainless downstream of the demister. Capture velocity at the manifold during connection and disconnection is 0.5 m/s minimum per AS 1668.2 LEV principles, with portable forced-ventilation fans deployed during transfer operations rather than fixed ducted ventilation.
Synthesis loop building zoning
The synthesis loop building combines a Zone 2 hydrogen IIC classification (from the syngas mix of hydrogen and nitrogen at 150-300 bar and 400-500 degrees C inside the converter) 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. The converter itself is inside a containment cell with localised forced ventilation at 20-30 ACH, isolated from the surrounding compressor building.
Methanol synthesis and other H2 carriers — Power-to-X chemistry
Some Australian hydrogen projects target methanol (CH3OH) instead of ammonia as the export carrier, particularly where CO2 from an adjacent industrial source is available. Methanol is produced by hydrogenation of CO2 over a copper-zinc-aluminium oxide catalyst at 200-300 degrees C and 50-100 bar. Methanol is a Class 3 flammable liquid under AS 1940 (flash point 11 degrees C) and is toxic at workplace exposure 200 ppm 8-hour TWA per Safe Work Australia WES. The methanol synthesis loop building requires Zone 2 hydrogen IIC classification on the syngas side plus AS 1940 flammable liquid handling controls on the methanol storage and product handling side. HVAC ductwork is 316L stainless throughout, with the methanol storage tank farm bunded per AS 1940 and ventilated to maintain less than 25 percent LEL methanol vapour in the bund space. Methanol is also being evaluated as a hydrogen carrier under the LOHC (liquid organic hydrogen carrier) pathway, alongside methylcyclohexane MCH and dibenzyltoluene. The Power-to-X chemistry across all of these pathways shares the same hazardous area zoning baseline and the same 316L stainless duct specification.
Materials selection — why 316L dominates hydrogen and ammonia ductwork
The single most important materials decision on a hydrogen project is the duct steel grade. Five 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 MPa). HVAC ductwork operates at low pressure (a few hundred pascal) and uses low-strength sheet metal (yield strength 200-350 MPa 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 face-centred-cubic austenitic structures are not susceptible.
Alkaline corrosion from electrolyser carryover
The dominant materials threat on alkaline electrolyser projects is alkaline corrosion. Fine droplets of 25-30 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 galvanised steel rapidly (within months), attacks aluminium within a year, and eventually attacks carbon steel as well. 316L stainless steel resists alkaline attack at the temperatures involved (up to 80 degrees C continuous), with corrosion rates below 0.05 mm per year — negligible over a 25-year plant life.
Ammonia attack on copper-bearing alloys
Anhydrous ammonia attacks copper, brass, bronze and zinc rapidly, forming soluble copper-ammine complexes that destroy copper-bearing components within hours of exposure. 316L stainless and aluminium are both ammonia-compatible at the temperatures involved. Any project with ammonia synthesis downstream eliminates copper from the airstream entirely — motor windings, refrigeration coil tubes, control valve internals and flexible duct connector wires.
Chloride stress corrosion on coastal sites
Australian hydrogen export terminals are largely coastal — Port Kembla NSW, Newcastle NSW, Bell Bay TAS, Hastings VIC, Kwinana WA, Port Hedland WA, Geraldton WA and Gladstone QLD all sit within 5 km of the coast with salt-spray exposure in the wind. Chloride stress corrosion cracking SCC is a known failure mode on 304 stainless at elevated temperature in chloride-laden environments, with documented service life under 10 years in Australian coastal industrial atmospheres. 316L stainless contains 2-3 percent molybdenum which substantially raises the chloride tolerance — service life on coastal sites pushes past 25 years. The cost premium of 316L over 304 (typically 30-40 percent on coil price) is recovered easily over the plant life.
Cleanability and weld quality
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, chloride contamination from coastal site air, and for any future expansion into ammonia or chlorinated chemistry. SBKJ recommends 316L for any duct downstream of an alkaline electrolyser cell stack, any duct in ammonia service, and any duct on a coastal site. 304L is acceptable for control room supply, workshop, office and substation rectifier rooms outside the zoned envelope. Galvanised carbon steel per AS 1397 is not permitted inside the electrolyser hall or ammonia loop building.
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 Australian 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 operate at 1-5 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 high-pressure pipework. The PRV discharge piping is normally hard pipe rather than HVAC duct (because it operates at higher 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. The SBKJ scope is limited to any low-pressure plenum or duct on the discharge side downstream of the relief device.
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 kg/h or more of hydrogen, discharging through a dedicated blowdown header to an elevated vent stack. Blowdown headers are hard pipe; the dispersion of the discharged hydrogen plume is modelled per HySafe protocols to confirm dilution below 25 percent LEL before reaching any building HVAC fresh air intake within 50 metres.
Flare stack ventilation
Some larger hydrogen projects (particularly green ammonia plants and the larger LH2 export terminals) 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. AS 1657 access platforms are mandatory at every elevation requiring routine inspection or maintenance.
KOH/NaOH chemical storage and dosing — caustic mist scrubber HVAC
Alkaline electrolyser plants include a 25-30 percent KOH or NaOH circulating electrolyte plus a make-up dosing system handling the consumption from gas-stream carryover. The chemical storage and dosing room is a wet room with caustic mist generation at the dosing pumps, sample points and tank vents. Safe Work Australia WES for caustic mist (KOH and NaOH together, expressed as alkali) is 2 mg/m3 ceiling. Local exhaust ventilation LEV at 0.5 m/s capture face velocity per AS 1668.2 LEV principles is mandatory at each release source, captured in 316L stainless duct (galvanised pits within weeks under caustic), routed through a caustic mist eliminator (chevron-style or stainless wire-mesh demister) before atmospheric discharge.
The dosing room HVAC supply is balanced against the LEV extract to maintain slight negative pressure relative to the surrounding electrolyser hall. Bund containment under AS 4326 (industrial chemical containment) is mandatory at the storage tank level. Personal protective equipment for routine entry includes face shield, chemical goggles, neoprene gauntlets and chemical-resistant apron per the Safe Work Australia hazardous chemicals code of practice.
On PEM electrolyser deconditioning (an end-of-life process where membranes are chemically broken down for reclaim), trace sulphuric acid mist is released; Safe Work Australia WES is 1 mg/m3. The deconditioning bay is a separate enclosed room with FRP (vinyl ester resin) duct on the acid mist run, captured at 0.5 m/s face velocity at each open vessel, routed through a packed-bed acid scrubber before discharge.
Demineralised water plant and feed water conditioning HVAC
Every electrolyser requires high-purity water feed — ASTM Type II or Type III demineralised water typically. The demin water plant uses reverse osmosis RO and electrodeionisation EDI to produce water at less than 1 microsiemens per centimetre conductivity. The plant is housed in a separate building with conventional commercial HVAC at 2-6 ACH, no hazardous area classification, galvanised duct acceptable. The HVAC scope here is minor and is essentially commercial-industrial baseline. Where the demin water plant adjoins the electrolyser hall, the wall between is fire-rated under AS 1530.4 and the demin building is held at positive pressure relative to the electrolyser hall side to prevent hydrogen migration into the demin space during an electrolyser hall upset.
Hydrogen quality analysis laboratory HVAC under ISO 14687
Every hydrogen export terminal and every commercial hydrogen refuelling station with fuel-cell vehicle off-take must demonstrate hydrogen fuel quality compliance to ISO 14687. The standard sets purity requirements for fuel cell vehicle hydrogen — minimum 99.97 percent H2 with strict limits on individual impurities (CO less than 0.2 ppm, H2S less than 4 ppb, total sulphur less than 4 ppb, CO2 less than 2 ppm, water less than 5 ppm and so on). Compliance verification requires laboratory-grade gas chromatograph GC and mass spectrometer MS instrumentation, typically housed in an on-site quality analysis laboratory.
The lab is a controlled-environment room at 22 plus/minus 2 degrees C and 45 plus/minus 10 percent RH. Particle classification typically ISO 14644-1 Class 8 (formerly Federal Standard 209E Class 100,000) to protect the GC and MS columns from particulate contamination. The lab includes a chemical fume hood operating at 0.5 m/s face velocity per AS/NZS 2243.8 and AS 1668.2 Section 5, with the fume hood duct in 316L stainless or PVC depending on analyte chemistry, routed to a dedicated lab exhaust stack with no recirculation.
Hydrogen carrier gas cylinders inside the lab are limited to 50 litre water-capacity each per AS 4332 storage and handling of gases, stored in a Type 5 G-size cylinder cabinet exhausted at 6-10 ACH with a dedicated stack discharge to atmosphere. Gas detection inside the cabinet is ISO 26142 compliant. The lab fresh air intake is located on the building exterior away from any hydrogen vent stack, with the standard 20 metre horizontal and 10 metre vertical separation.
Substation and DC rectifier room HVAC
Every electrolyser hall is fed by a high-current DC supply from a substation with AC-to-DC rectifier transformers. A 100 MW electrolyser plant typically requires 110-130 MVA of installed transformer capacity, generating substantial heat in the rectifier rooms — typically 1-2 percent of rectifier throughput rejected as heat, so 1-2 MW of cooling load on the rectifier room. Cooling is typically split between forced ventilation (to remove heat to outside) and chilled water (for tight temperature control on the rectifier control electronics).
Rectifier room HVAC is conventional industrial scope — galvanised duct acceptable, no hazardous area classification (the substation building is set back from the electrolyser hall and is outside the zoned envelope). Ventilation rates are 10-20 ACH driven by heat removal duty. The room is held at slight positive pressure relative to outside to keep dust out of the rectifier cabinets. The control room HVAC and the rectifier room HVAC are separate independent systems with no shared ductwork. SBKJ supplies the galvanised rectangular and spiral round ductwork on the SBAL-V and SBTF for the rectifier room scope; the active rectifier equipment is sourced by the EPC contractor from specialist power electronics vendors.
Hydrogen storage vessel test bay HVAC
For projects with on-site hydrogen storage vessel testing — particularly the Type IV composite cylinder fatigue and burst testing required under ISO 19880-3 and ECE R134 for vehicle on-board storage — a dedicated test bay is included in the facility scope. The test bay performs hydrostatic pressure cycling, burst testing and fire exposure testing on cylinders inside a blast-rated enclosure. HVAC requirements are mechanical ventilation at 6-12 ACH during testing, hydrogen detection per ISO 26142 (because hydraulic fluid leakage during cycling can release small quantities of dissolved hydrogen), and forced exhaust during burst testing to clear the enclosure of any hydrogen residue before personnel re-entry.
The test bay enclosure walls are rated for the maximum projected fragment energy per ASME Section VIII or equivalent. HVAC ductwork penetrations through the blast wall include blast-rated fire dampers with frangible closure on overpressure. The test bay is held at slight negative pressure relative to surrounding workshop areas to contain any hydrogen release. 316L stainless duct throughout the bay envelope. Active Australian operators with vessel test capacity: Quantum Fuel Systems (US, with Australian distribution), Hexagon Purus Australia and selected internal labs at Yara, Coregas and CSBP.
Solar farm and wind farm co-located electrolyser HVAC
Many Australian green hydrogen projects co-locate a solar PV or wind farm with the electrolyser. The renewable generation is unfenced (solar) or fenced standalone (wind), and the electrolyser sits in a small control building inside the renewable site boundary. The Hydrogen Park Murray Valley project at Mildura VIC is a current operating example; AGL's Hunter Valley pilot and several Squadron Energy / Andrew Forrest portfolio sites in NSW follow a similar layout.
The small site control building HVAC is conventional commercial scope (galvanised supply, 4-8 ACH, AS 1668.2 baseline) on the office and switch room side, with hydrogen-specific scope only on any enclosed electrolyser package. The electrolyser package is typically supplied by the vendor (Plug Power, Nel, ITM Power, Enapter, Hysata or local equivalent) as a containerised unit with integral HVAC and detection inside the container envelope. SBKJ's scope in this configuration is limited to the building shell HVAC and the substation rectifier room; the electrolyser package itself comes pre-fitted by the vendor.
Office, control room and worker amenity HVAC
The office and worker amenity blocks at every hydrogen project are conventional commercial HVAC scope under AS 1668.2 with NCC Volume One Section J energy provisions. Galvanised supply duct on the SBKJ SBAL-V at 5-7 ACH is the standard configuration. The control room is a positive-pressure refuge as discussed above; the office and amenity blocks are typically physically separated from the control room and from the process plant, often in a separate site office building 50-100 metres from the plant battery limit. Worker amenity (showers, toilets, lunch room, training room) is unclassified scope to AS 1668.2 baseline.
Maintenance workshop HVAC — welding for hydrogen piping
The site maintenance workshop handles welding repair, galvanising touch-up and pipe fabrication for the hydrogen project. Hydrogen piping is fabricated in 316L stainless minimum, sometimes Inconel 625 for the high-temperature SOEC service. Welding equipment in the workshop is GTAW (TIG) with argon shielding for stainless, GTAW with helium-argon for Inconel, and stick or MIG for any structural mild steel work. Welding fume extraction is mandatory at every welding bay, captured at source with a flexible extraction arm at 1 m/s minimum face velocity per AS 1668.2 Appendix E weld fume control, routed in galvanised duct to a HEPA-filtered welding fume cartridge unit.
The workshop is unclassified scope outside the zoned hydrogen envelope. Galvanised duct acceptable on supply and welding fume extract; aluminium-clad insulated 304L on the grinding-and-buffing area exhaust (no spark risk in the open workshop). The workshop is held at slight negative pressure relative to outdoor air to contain welding fume during operation. Heat treatment furnace (for stress-relief post-weld on 316L heavy section piping) is a separate enclosed bay with a stack discharge.
Australian green hydrogen project pipeline — current state May 2026
Australia is 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 programs — the Australian Government Hydrogen Headstart program (AUD 2 billion in production-linked subsidy over two rounds) and the Hydrogen Production Tax Incentive (HPTI, 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.
Fortescue Future Industries (FFI) and Fortescue (ASX:FMG)
Andrew Forrest's Fortescue is the most active Australian hydrogen developer. The Gladstone QLD electrolyser factory (PEM technology under licence from Plug Power, joint venture) is in operation manufacturing 2 MW PEM electrolyser modules for export and domestic deployment. The Pilbara green hydrogen production project targets multi-gigawatt scale at the Christmas Creek and Eliwana mining operations, supplying onsite hydrogen-fuelled mining haul trucks alongside export volumes. The Holmaneskjær Norway project (joint venture with Statkraft) is a sister international development. Fortescue Williamtown NSW operates one of the early Australian HRS sites for fleet demonstration.
Stanwell Corporation — CQ-H2 Central Queensland
The Central Queensland Hydrogen project CQ-H2 led by Stanwell Corporation with Iwatani Corporation, Marubeni and Keppel as joint venture partners targets 720 MW of electrolyser capacity at the 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 via Iwatani. CQ-H2 received Hydrogen Headstart funding in the first allocation round. The project includes a dedicated LH2 liquefaction plant — one of the larger LH2 scopes in the global pipeline.
Woodside Energy (ASX:WDS)
Woodside is developing the Pilbara Hydrogen project plus an integrated H2-and-ammonia export project at Bell Bay Tasmania in partnership with Mitsui. The Pilbara development is at FEED with multi-gigawatt scale electrolyser and ammonia synthesis; Bell Bay is a smaller initial scope (around 200 MW first phase) with Tasmania's renewable hydroelectric and wind grid providing the renewable energy input.
Origin Energy (ASX:ORG)
Origin's Hunter Valley Hydrogen Hub at Kooragang Island NSW targets up to 55 MW of PEM 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. Origin separately holds the Bell Bay TAS hydrogen-to-ammonia project (with Mitsui) at the same site as Woodside's parallel scope.
AGL Energy (ASX:AGL) and Hydrogen Park Murray Valley
AGL Energy operates the Hydrogen Park Murray Valley facility at Mildura VIC — a small-scale (1-2 MW) green hydrogen production and 10 percent blending into the local gas distribution network. AGL is in early development on larger-scale hydrogen production at multiple NSW sites including the Hunter Valley.
Province Resources — HyEnergy WA
Province Resources is developing the HyEnergy Project in the Gascoyne region of Western Australia targeting up to 8 GW of renewable energy and 4 GW of electrolyser capacity producing green ammonia for export. The project is at EIS (environmental impact statement) stage with first-phase production targeted for the late 2020s.
BP Australia — Kwinana and Geraldton WA
BP Australia is developing green hydrogen capacity at the Kwinana refinery (post-fossil-fuel refining transition to hydrogen production for industrial off-takers) and at Geraldton in the Mid-West for the H2Kwinana and H2Geraldton projects.
Shell Australia — Geelong and Hexham
Shell Australia is developing green hydrogen capacity at the Geelong refinery (transitioning from fossil refining) and at Hexham NSW for the broader Newcastle industrial corridor off-take.
Industrial gas suppliers — BOC, Air Liquide, Coregas, Iwatani, Sumitomo
BOC (the Linde Group Australian subsidiary), Air Liquide Australia and Coregas (a Wesfarmers subsidiary) are the established Australian industrial gas suppliers transitioning their merchant hydrogen supply from grey (steam methane reforming) to green (electrolyser). Iwatani Australia and Sumitomo Hydrogen Australia are the Japanese gas-major participants with Gladstone QLD and partner projects nationally.
Hysata — capillary-fed alkaline (Wollongong NSW)
Hysata is the leading Australian electrolyser R&D commercial spinout — a UNSW / University of Wollongong joint venture commercialising a capillary-fed alkaline electrolyser at system efficiency above 95 percent. First commercial-scale units are in late-stage validation testing at the Wollongong demonstration plant; Hysata supply chain integration with Australian fabricators including SBKJ's customer base is in early planning.
ATCO Australia — Jandakot WA
ATCO Australia operates the Jandakot Clean Energy Innovation Hub in WA — a 250 kW pilot electrolyser plus HRS plus 10 percent hydrogen blending into the local gas distribution network. The site is a working demonstrator of integrated production, distribution and dispensing at suburban scale and is widely referenced as the proof-of-concept for larger Australian projects.
Australian ammonia operator base
Ammonia is the dominant hydrogen export carrier under development in Australia, and the existing ammonia operator base provides the operational and HVAC reference template that new green-ammonia projects build on.
Yara Pilbara Fertilisers (Karratha WA)
Yara Pilbara at Karratha WA is the largest ammonia and urea producer in Australia, currently fossil-based (Burrup natural gas to ammonia to urea). Yara has announced green-ammonia transition projects on the same Karratha site, with first-phase electrolyser capacity at 10 MW pilot scale rising to multi-hundred-MW commercial. The existing fossil ammonia HVAC scope is the engineering reference template for the green transition.
Orica — Yarwun QLD and other sites
Orica Yarwun in Gladstone QLD is a major ammonia and ammonium nitrate explosives producer for the Australian mining sector. Orica has announced green-hydrogen-derived ammonia integration at Yarwun under partnership with Stanwell and other regional renewable developers.
CSBP — Kwinana WA
CSBP at Kwinana (the Wesfarmers Chemicals Energy and Fertilisers WesCEF subsidiary) produces ammonia, ammonium nitrate and ammonium phosphate for WA mining and agricultural markets. Like Yara, CSBP is in early-stage transition planning for green-hydrogen-derived ammonia at Kwinana.
Incitec Pivot (ASX:IPL) — Phosphate Hill, Gibson Island, Moranbah
Incitec Pivot is the largest Australian fertiliser producer with ammonia capacity at Phosphate Hill QLD (closed in 2023), Gibson Island Brisbane (the Origin partnership for green ammonia conversion targets first product mid-2020s) and Moranbah QLD. The Gibson Island green-ammonia conversion is the most advanced of the green-ammonia transitions in Australia.
SBKJ machinery for green hydrogen, ammonia, refuelling and export terminal projects
SBKJ supplies HVAC ductwork fabrication machinery to Australian and international hydrogen, ammonia, cryogenic and refuelling project fabricators from the Box Hill North VIC office. The standard machine specifications on these projects are:
SBAL-V auto duct line — 316L stainless configuration
The SBAL-V auto duct production line in stainless configuration accepts 316L coil 0.7-1.5 mm thick and produces TDF flange rectangular ductwork from 200 mm wide up to 1,500 mm 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 on the finished product. Line speed on 1 mm 316L is 8-12 metres per minute. The standard SBAL-V control panel is non-Ex (the machine sits in a fabrication shop, not in a zoned plant area), with an ATEX Zone 2 panel option for fabrication shops integrated into the main plant battery limits. For full machine specification see the SBAL-V versus SBAL-III comparison guide.
SBTF spiral tubeformer — stainless variants
The SBTF stainless spiral tubeformer (variants SBTF-1500, SBTF-1500C, SBTF-1602 and SBTF-2020) produces 316L spiral round ductwork from 100 mm diameter up to 1,500 mm or 2,020 mm diameter (model-dependent), in continuous lengths up to the available coil width. 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 mm 316L coil is 6-10 metres per minute.
SBSF-1525 stitchwelder for stainless seam closure
The SBSF-1525 stitchwelder handles longitudinal seam welding on stainless rectangular duct that is mandatory for any Zone 1 or Zone 0 service under AS/NZS 60079.14 — Pittsburgh seams are not permitted in Zone 1 because the seam can lift under hydrogen overpressure and create a localised release path. The SBSF-1525 produces a continuously welded longitudinal seam at line speed compatible with the SBAL-V output. The companion GTAW (TIG) seam welder for the highest-integrity applications operates in argon shielding gas for clean 316L weldments.
SBPC1500 plasma cutter for 316L sheet
The SBPC1500 plasma cutter handles 316L sheet penetrations for branch take-offs, access panel cutouts and damper frame openings. Plasma cutting is preferred over oxy-fuel for stainless because it produces a cleaner cut with minimal heat-affected-zone discolouration and no surface contamination. Post-cut grinding and pickle-and-passivate restores the chromium oxide passive layer.
Welding and finishing equipment for hydrogen-grade fabrication
Stainless ductwork on hydrogen projects routinely requires continuously welded longitudinal seams plus continuously welded transverse joints in Zone 0 service. SBKJ supplies GTAW (TIG) seam welders, plasma seam welders and resistance 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. For full welding methodology see the welding methods for HVAC duct fabrication guide.
Quality and traceability
Hydrogen plant fabricators normally require mill certificates on every coil and weld procedure qualification records WPQR on every welder per AS/NZS 1554.6 and ISO 15614. SBKJ machines support material traceability through coil tag readers and weld parameter logging at the PLC. The standard SBKJ Factory Acceptance Test (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 at the SBKJ project office before the machine ships. For the full SBKJ machine fleet see the machines page; for product detail on the SBAL-V specifically, see the SBAL-V product page.
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 galvanised work.
Material cost benchmarks (May 2026)
316L stainless coil at 1 mm thickness costs approximately 4-6 times equivalent galvanised coil per kilogram, depending on mill source and order volume. Total finished duct cost (material plus fabrication labour plus welding plus surface finishing) typically runs 3-5 times equivalent galvanised commercial work per linear metre. A 1,500 mm wide by 600 mm deep 316L stainless rectangular duct typically lands at AUD 700-1,000 per linear metre installed in 2026 markets, against AUD 180-280 per linear metre for the equivalent galvanised. Spiral round 316L on the SBTF-1500 at 1,500 mm diameter lands at AUD 450-650 per linear metre installed, against AUD 110-160 for the galvanised equivalent.
Lead time benchmarks
Stainless coil lead time from Australian (BlueScope no longer rolls 316L commercially), European (Outokumpu, Aperam) or Asian (POSCO, Tata, Aichi Steel) mills is currently 10-16 weeks for 316L in HVAC-typical thicknesses (0.7-1.5 mm). Fabrication on the SBAL-V or SBTF runs at 8-12 metres per minute output, so a typical 3,000-metre electrolyser hall scope fabricates in 6-8 weeks of single-shift operation. Field installation typically runs 1-2 metres per metalworker-hour for stainless duct (against 3-5 metres for galvanised) due to welding and finishing requirements. End-to-end from purchase order to installed and commissioned duct system is typically 6-9 months on a hydrogen project, against 3-5 months on equivalent commercial work. The typical Australian hydrogen project HVAC duct package for a 100 MW electrolyser plant runs AUD 6-12 million depending on scope and location, with the SBKJ machine-driven local fabrication element delivering substantial cost saving over imported pre-fabricated duct.
SBKJ machine delivery lead time
The SBAL-V, SBTF, SBSF-1525 and SBPC1500 are typically delivered within 16-22 weeks of order from the SBKJ Box Hill North VIC project office, including stainless tooling configuration and Factory Acceptance Test. See the HVAC duct machine buyer's checklist for full procurement guidance and the duct production line total cost of ownership analysis for life-cycle commercial assessment.
How SBKJ specifies HVAC ductwork on an Australian hydrogen project
The procedure SBKJ engineers walk through with Australian hydrogen project fabricators looks like the following sequence, which has evolved from supplying machinery to hazardous area projects across hydrogen, ammonia, LNG, lithium battery and petrochemical sectors over the last decade.
- Read the hazardous area classification drawing. The HAC drawing is the master document, signed off by a Certified Hazardous Area Auditor under the IECEx CoPC scheme. 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, methanol or LH2 downstream synthesis scope. If green ammonia, methanol or LH2 is downstream, the materials specification extends across the whole plant — copper-free motors, all-aluminium coils, dual-rated detection, additional caustic mist or acid mist scrubber duct. SBKJ confirms this at quotation stage to size the coil order correctly.
- Confirm the export terminal scope. If the project is an export terminal (Bell Bay TAS, Gladstone QLD, Port Hedland WA, Geraldton WA), the marine loading jetty Zone 1 zoning, the storage tank farm ventilation strategy and the export carrier conditioning plant all add to the HVAC scope. SBKJ confirms terminal scope separately because the loading jetty hazardous area zoning is distinct from the production-plant zoning.
- Confirm the HRS dispenser scope. If hydrogen refuelling stations are on the project (Fortescue Williamtown, Coregas Sydney, ATCO Jandakot, HyDrive portfolio), the ISO 19880-1 canopy ventilation strategy, the dispenser skid HVAC and the storage skid ventilation all add to the HVAC scope.
- Size the duct cross-section to face velocity. 8-10 m/s on supply collection, 12-15 m/s on exhaust trunk. Cross-section sized for 200-300 Pa 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 (via SBSF-1525 stitchwelder or GTAW seam welder) 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 (316L UNS S31603), thickness (typically 0.7, 1.0 or 1.5 mm), surface finish (2B mill finish standard, No. 4 brushed for visual areas) and mill certificate format. Mill certificates required for every coil and traceable to every piece of finished duct.
- Schedule fabrication. Stainless duct fabrication on the SBAL-V at 8-12 m/min output translates to 50-70 metres of finished duct per shift after handling and inspection. A typical 100 MW electrolyser hall requires 2,000-4,000 linear metres of duct, fabricated in 30-60 shifts.
- Test and commission. Pressure test installed ductwork to 1.5 times design operating pressure. AS 4254 leakage Class A standard. Witness test by buyer or NATA-certified 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 8-10 months before first hydrogen.
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 4-8 per hour during welding activity, dropping to 2 per hour during non-active periods. Hydrogen detection is not commissioned during construction (because there is no hydrogen present), but oxygen-deficiency monitoring may be required for confined-space welding inside vessel internals.
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 30-60 days at design operating conditions) before any hydrogen is admitted to the cell stacks. This sequencing protects 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.
Inspection, maintenance and operational compliance under AS/NZS 60079.17
Once commissioned, a hydrogen plant HVAC system enters a structured inspection and maintenance regime under AS/NZS 60079.17 (adopting IEC 60079-17 verbatim). 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 and 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, or as part of statutory turnaround at 5-yearly intervals.
AS 1851 fire damper maintenance applies in parallel — drop testing on every fire damper every 12 months under AS 1851 routine maintenance schedule. 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 Australian standards govern HVAC ductwork in a green hydrogen production facility?
AS 1668.2 mechanical ventilation, AS 4254 ductwork construction, AS 1530.4 fire-rated penetrations, AS/NZS 60079 hazardous area Zone 0/1/2 for hydrogen IIC, AS 4332 gas storage, AS 4564 gas supply, AS 4647 and AS 4646 gas equipment, AS 1851 fire damper, AS 1657 platforms, plus ISO 26142 hydrogen detection, ISO 14687 fuel quality, ISO 19880 fuelling station, ATEX Directive 2014/34/EU and NFPA 2 cross-reference. The Standards Australia ME-093 committee and the Australian Hydrogen Council Standards Strategy shape the national framework, with HySafe protocols providing international reference for safety practice.
What hazardous area zoning applies inside an Australian electrolyser hall under AS/NZS 60079?
Electrolyser halls are Zone 2 across the building envelope with localised Zone 1 within 1-3 metres of stack manifolds, gas-liquid separators and vent stack roots. Cell stack interiors are Zone 0. Gas group IIC, temperature class T1. Every HVAC active device installed in Zone 1 or Zone 2 must carry IECEx or ATEX certification with gas group IIC and equipment protection level Gb (Zone 1) or Gc (Zone 2). The HAC drawing must be signed off by a Certified Hazardous Area Auditor under the IECEx CoPC scheme before any HVAC equipment is specified.
What ventilation rate does an Australian electrolyser hall require?
6-12 air changes per hour sized to dilute worst-case credible hydrogen leak below 25 percent of LEL (1 percent H2 by volume). For a 100 MW hall at 5,000-7,000 square metres and 12 metre ceiling, that is 60,000-150,000 cubic metres per hour of supply and exhaust. Exhaust grilles within 300 mm of the highest ceiling point because hydrogen rises rapidly (relative density 0.0695). SBKJ ductwork sizing uses 8-10 m/s on supply collection and 12-15 m/s on trunk runs.
Why is 316L stainless mandatory for hydrogen and ammonia HVAC ductwork?
Alkaline corrosion from KOH carryover, hydrogen embrittlement of carbon steel under elevated H2 partial pressure, ammonia attack on copper-bearing alloys, chloride stress corrosion on coastal Australian sites, and cleanability and weld quality with low-carbon 316L. The combination forces 316L on any duct downstream of electrolyser stack, gas-liquid separator, ammonia synthesis loop or hydrogen vent stack. 304L is acceptable for control room and unclassified scope outside the zoned envelope.
How is the hydrogen detection grid designed under ISO 26142?
IECEx-certified hydrogen detectors at ceiling level on maximum 10 metre by 10 metre grid, ISO 26142 performance criteria (response below 30 seconds at 1 percent H2, plus/minus 5 percent FS accuracy). First alarm at 25 percent LEL (1 percent H2), second alarm at 50 percent LEL (2 percent H2). Sensor calibration on 6-month cycle. Detection system independent of BMS but interlocked with HVAC controls so detector trip overrides any manual mode.
What HVAC ductwork applies to a hydrogen refuelling station HRS?
ISO 19880-1 dictates canopy ventilation strategy — natural through 50 percent open or louvred perimeter, or mechanical sized to less than 25 percent LEL. Dispenser is Zone 1 within 1 metre and Zone 2 within 3 metres. Detection at canopy peak (ISO 26142), alarm at 10 and 25 percent LEL with refuelling cut-off. Enclosed compressor and storage skid: 12-20 ACH displacement ventilation, 316L stainless duct, ATEX-rated active equipment. Australian sites: Fortescue Williamtown NSW, Coregas Sydney, ATCO Jandakot WA, Hydrogen Park Murray Valley Mildura VIC, HyDrive portfolio.
What HVAC ductwork applies to green ammonia synthesis?
Dual-zoned: Zone 2 hydrogen IIC on syngas plus separate toxic-gas zone for ammonia. Ammonia detection at 25 ppm 8-hour TWA and 35 ppm STEL per Safe Work Australia. 316L stainless duct throughout, copper-free, aluminium-wound motors, all-aluminium coils, aluminium-bronze-free dampers. Active Australian ammonia operators: Yara Pilbara, Orica Yarwun, CSBP Kwinana, Incitec Pivot Gibson Island and Moranbah. New green-ammonia projects at Bell Bay TAS, Port Hedland, Gladstone QLD.
How are LH2 cryogenic plants ventilated?
Displacement ventilation at 6-10 ACH with low-level supply and high-level exhaust. Oxygen monitoring at floor level (oxygen-enriched air is denser than ambient) per Safe Work Australia 19.5/23.5 percent limits. Cold LH2 vapour is initially denser than air, sinking before warming and rising. BLEVE risk drives 30-50 metre separation from occupied buildings per QRA. 316L stainless duct throughout. PRV discharge hard pipe, never routed through HVAC ductwork.
Are SBKJ machines suitable for fabricating Australian hydrogen project ductwork?
Yes. The SBAL-V auto duct line accepts 316L coil 0.7-1.5 mm thick producing TDF rectangular duct 200-1,500 mm wide at 8-12 m/min. SBTF spiral tubeformer (SBTF-1500, SBTF-1500C, SBTF-1602, SBTF-2020) produces 316L spiral round duct 100-2,020 mm diameter at 6-10 m/min. SBSF-1525 stitchwelder handles continuously welded longitudinal seams required in Zone 0/1 service. SBPC1500 plasma cutter handles 316L sheet penetrations. SBKJ Box Hill North VIC office supports specification, FAT and on-site commissioning.
What is the typical lead time and cost for a 100 MW Australian electrolyser HVAC duct package?
AUD 6-12 million depending on scope and location. Stainless coil lead time 10-16 weeks from European or Asian mills. Fabrication on SBAL-V at 8-12 m/min, 30-60 shifts for 2,000-4,000 metres of duct. Field installation 1-2 metres per metalworker-hour for stainless. End-to-end PO to installed and commissioned duct system is 6-9 months. SBKJ machine delivery is 16-22 weeks from order including stainless tooling and FAT.
Related guides
For adjacent industry references and material decisions, see the following SBKJ insights:
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