Industrial Gas, Air Separation Unit, Oxygen, Nitrogen, Argon, Acetylene, CO2, Hydrogen & Medical Gas Production HVAC Duct Guide

1. Why industrial-gas HVAC is its own engineering discipline

Industrial gas is the quiet utility under everything else Australia makes. Oxygen for steelmaking at Port Kembla and for every hospital theatre, nitrogen for food packaging and electronics inerting, argon for welding and metallurgy, hydrogen for the emerging clean-energy economy, carbon dioxide for breweries and abattoirs, acetylene for cutting and brazing, nitrous oxide and medical air for healthcare — all of it is produced, compressed, blended and filled into cylinders at a handful of plants run by a small number of large operators. And the HVAC inside those plants is unlike any other industrial ventilation problem, because the hazards are invisible, the consequences are immediate, and the same atmospheric variable — the oxygen concentration of the air a worker breathes — is dangerous in both directions.

The safe range for oxygen in breathing air is narrow: 19.5 percent to 23.5 percent by volume. Normal air sits at 20.9 percent. Push the number up past 23.5 percent and the atmosphere becomes oxygen-enriched: the energy needed to start a fire collapses, the flammable range of every fuel widens, materials that smoulder reluctantly in normal air burn fiercely, and substances that do not normally burn at all — clothing, hair, lubricants, even some metals — will ignite from a spark and burn with shocking violence. Pull the number down below 19.5 percent — which happens the instant nitrogen, argon, helium, carbon dioxide or nitrous oxide displaces air in an enclosed or poorly ventilated space — and the atmosphere becomes oxygen-depleted: a simple asphyxiant gives no warning, no smell, no taste, no colour, and a worker who walks into a nitrogen-rich pocket can lose consciousness in a breath or two and die within minutes. The asphyxiation hazard from inert-gas oxygen depletion has historically been the single largest cause of fatalities in the global industrial-gas industry, and oxygen enrichment fire is its mirror image. An industrial-gas HVAC designer who treats the ventilation as ordinary dilution ventilation, sized to a building-volume air-change figure, has not understood the problem. The ventilation here is a life-safety system, and the ductwork is part of it.

This guide writes against the full breadth of the Australian industrial-gas sector as it exists in 2026. BOC, a Linde company, is the country’s largest industrial-gas supplier, operating air separation units at Port Kembla (feeding the BlueScope steelworks), Westernport in Victoria, Kwinana in Western Australia and Yarwun near Gladstone in Queensland, plus medical-gas production under BOC Healthcare, hydrogen, and CO2 supply. Air Liquide Australia runs air separation and medical-gas production, with Air Liquide Healthcare supplying hospital oxygen, nitrous oxide and medical air across the country. Coregas, owned by Wesfarmers and proudly Australian, produces hydrogen and a full range of industrial and specialty gases from Port Kembla in New South Wales and multiple other sites, and has been at the front of Australian hydrogen-mobility refuelling. Supagas, also Australian-owned and multi-site, is a major filler of CO2, LPG, oxygen, nitrogen, argon and balloon gas. Renegade Gas and its Speedgas LPG brand serve the LPG and industrial-gas market. Air Products supplies bulk and specialty gases into Australian industry. Hydrogen production in Australia is led by Coregas and BOC; food-grade CO2 is supplied by Supagas and BOC, much of it recovered from brewery and ethanol fermentation; and medical gas is the domain of BOC and Air Liquide Healthcare. The geography spans Port Kembla and Wetherill Park and the broader Western Sydney industrial belt in New South Wales, Yarwun and Gladstone in Queensland, Kwinana in Western Australia, Westernport and Dandenong in Victoria, and Adelaide in South Australia.

Across this sector, the ductwork has to satisfy several demands at once. It must protect against oxygen enrichment fire and oxygen depletion asphyxiation simultaneously, which means both high-level and low-level extract and fixed oxygen monitoring on both set-points. It must be oxygen-clean — free of oil, grease and hydrocarbon residue that ignite in enriched atmospheres. It must classify and serve flammable-gas hazardous areas for acetylene and hydrogen under AS/NZS 60079.10.1, with conductive, bonded, earthed duct and Ex-rated plant. It must manage gas stratification — heavy gases pooling low, light gases rising high. It must be corrosion-resistant against cold moist cryogenic-area air, against the acid and food-process environment of CO2 recovery, and against the hygiene-cleaning regime of a medical-gas plant. And it must capture welding fume from the fabrication and repair of the cylinders, skids and manifolds that the whole industry runs on. Each demand is manageable alone; together they explain why a generic commercial fabricator who treats a gas plant as just another industrial shed loses money on the first job and never sees the second.

This guide walks the regulatory backbone first, then maps the gas plant area by area — ASU, oxygen, nitrogen and argon, cylinder hall, acetylene, hydrogen, CO2, medical gas, specialty blending, fabrication — and closes with the SBKJ machine configuration that gives an Australian fabricator the production envelope to serve this market from Box Hill North VIC across the country.

2. The Australian regulatory stack — AS 1668, AS 4254, AS/NZS 60079, AS 2896, AS 4332, AS/NZS 1596, NFPA 55, ADG Code

Industrial-gas HVAC in Australia sits at the intersection of mechanical-ventilation standards, oxygen-atmosphere and exposure-standard compliance, hazardous-area electrical compliance, medical-gas and cylinder-storage standards, pressure-vessel context and dangerous-goods transport rules. Miss one and the result is a notice from SafeWork Australia, the state EPA, the Therapeutic Goods Administration or the dangerous-goods regulator. The stack splits into building and ventilation, occupational exposure and atmosphere, hazardous-area, medical-gas and cylinder, and US cross-reference.

2.1 AS 1668.1 and AS 1668.2 — fire mode, mechanical ventilation and dilution

AS 1668.1 covers the fire and smoke control aspects of air-handling systems — relevant where gas-plant ductwork passes through fire compartments and where ventilation must continue or shut down in a fire mode. AS 1668.2 is the umbrella mechanical-ventilation and required-outdoor-air standard, and it is the day-to-day reference for dilution and workplace-exposure-standard (WES) control in a gas plant. Industrial-gas plants are NCC Class 8 industrial occupancy. AS 1668.2 sets the framework for diluting contaminants and managing make-up air, and in a gas plant its most important principle is that every cubic metre extracted from a filling hall, an ASU enclosure or a CO2 room must be replaced by controlled make-up air, keeping zones at the intended pressure relationship and preventing inert or asphyxiant gas from migrating into occupied spaces. AS 1668.2 also underpins the dilution calculation that sizes extract to hold a credible leak within the safe oxygen band and below the LEL of any flammable gas.

2.2 AS/NZS 4254.1 and AS/NZS 4254.2 — sheet-metal and flexible duct construction

AS/NZS 4254.1 (sheet metal) and AS/NZS 4254.2 (flexible) govern duct construction across the normal pressure ranges — low pressure to 500 Pa, medium pressure to 1000 Pa and high pressure to 2500 Pa. The great majority of gas-plant supply, general extract, cylinder-hall dilution and hazardous-area extract sits inside the AS 4254 ranges. Compressor after-cooler ducting and any warm regeneration exhaust at elevated temperature may run beyond AS 4254 in their hot section and require purpose-engineered construction, with AS 4254 picking up again downstream on the cool side. Construction class, sealing class and reinforcement all flow from the design pressure and the duty.

2.3 AS 1530.4 — fire resistance of building elements

AS 1530.4 covers fire-resistance testing of building elements, including fire-rated ductwork penetrations through fire compartments. In a gas plant this matters at every wall and floor penetration between the filling hall, the cylinder store, the compressor hall and adjacent office, switchroom or amenities space. The penetration is built to the required fire-resistance level (FRL) — commonly a 250 degree / 2 hour rating on the duct element — with fire dampers to AS 1682 and the surrounding assembly meeting the FRL called by the building’s NCC approval.

2.4 AS/NZS 60079.10.1 and 60079.10.2 — explosive atmospheres, the dominant electrical-safety standard

AS/NZS 60079 is the hazardous-area-classification standard, adopting the IEC 60079 series. For an industrial-gas plant the gas part — AS/NZS 60079.10.1 — is the one that bites hardest, because acetylene and hydrogen filling, and any flammable-gas blending, create flammable-gas atmospheres:

• Zone 0: A flammable gas atmosphere is present continuously or for long periods — typically the interior of process equipment and vessels handling the flammable gas.
• Zone 1: A flammable gas atmosphere is likely in normal operation — the immediate area around acetylene and hydrogen filling connections, manifold vents, generator vents and decanting points.
• Zone 2: A flammable gas atmosphere is unlikely in normal operation and short-lived if it occurs — the general acetylene or hydrogen hall around the Zone 1 envelopes.

AS/NZS 60079.10.2 covers explosible-dust atmospheres, relevant to calcium-carbide and lime dust in carbide-route acetylene generation. AS/NZS 60079 drives Ex-rated equipment selection for fans, motors, instruments, duct-mounted sensors and lighting in and near the zones. Ductwork in a flammable-gas zone must be conductive throughout (316L stainless is the default), continuously bonded with conductive flange gaskets, externally earthed to the building grid, and verified at commissioning with documented resistance below 1 ohm to ground at every section. The wider AS/NZS 60079 family — 60079.0 general requirements through 60079.14 installation design, 60079.17 inspection and maintenance, and the equipment-protection parts — governs the electrical equipment itself.

2.5 AS 2896 — medical gas systems

AS 2896 covers medical gas pipeline systems in healthcare facilities and is the reference Australian medical-gas standard. In a medical-gas production and filling plant it sets the expectation for cleanliness, identification, and the integrity of oxygen, nitrous oxide and medical-air systems, and it underpins the hygienic, cleanable, hermetically constructed ductwork that medical-gas manufacturing demands. Medical-gas manufacture in Australia also falls under the Therapeutic Goods Administration as a therapeutic good, so the production environment, its ventilation, and its documentation must support TGA manufacturing requirements alongside AS 2896.

2.6 AS 4332 and AS/NZS 1596 — cylinder storage and LPG

AS 4332 covers the storage and handling of gases in cylinders and is the controlling Australian standard for cylinder stores and filling areas. It sets ventilation expectations for cylinder storage — including the central principle that storage and handling areas for compressed gases must be well ventilated, with attention to both high and low level depending on gas density, to prevent the accumulation of flammable or asphyxiant gas. AS/NZS 1596 covers the storage and handling of LPG, relevant to the LPG filling that operators such as Supagas and Renegade Gas / Speedgas run alongside industrial gases; LPG is heavier than air and demands low-level ventilation and AS/NZS 60079 zoning.

2.7 NFPA 55, NFPA 68 and NFPA 69 — US cross-references

NFPA 55 (Compressed Gases and Cryogenic Fluids Code) is the US National Fire Protection Association code referenced by many Australian industrial-gas operators and insurers as a detailed engineering reference where AS standards are higher-level, covering bulk and cylinder storage, ventilation, separation distances and detection for oxygen, inert gases, flammable gases and cryogenic fluids. NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention by inerting and other means) are referenced where a flammable-gas or combustible-dust hazard (for example carbide dust in acetylene generation) requires engineered explosion protection and isolation between any collector and the inbound duct.

2.8 AS 3580, AS 3580-series and state EPA emissions

AS 3580 and its series cover methods for sampling and analysis of ambient air, relevant to stack-discharge monitoring and the conditions of a state EPA licence. A gas plant’s discharge points — vent stacks, CO2 process vents, regeneration exhaust and any combustion exhaust on hydrogen reforming — sit under an EPA licence that sets emission limits and monitoring obligations, and the HVAC stack design must support compliant, monitorable discharge.

2.9 AS/NZS 1715, AS/NZS 1716, AS 1210, AS 4024 and the ADG Code

AS/NZS 1715 (selection, use and maintenance of respiratory protective equipment) and AS/NZS 1716 (respiratory protective equipment) govern the supplied-air and self-contained breathing apparatus that gas-plant operators wear for entry into potentially oxygen-deficient or oxygen-enriched zones — RPE is the last line, not the first, and ventilation is the primary control. AS 1210 (pressure vessels) sits in the background as the design code for the vessels, columns and receivers in the plant. AS 4024 (safety of machinery) governs guarding and access on the fabrication machinery and on plant equipment. AS/NZS 3000 (the Wiring Rules) governs the electrical installation, interfacing with AS/NZS 60079 in the hazardous areas. The Australian Dangerous Goods (ADG) Code governs the road transport of the filled cylinders and bulk gas, and the Globally Harmonised System (GHS) governs the classification and labelling of the hazardous chemicals on site. NCC Section J and ASHRAE 62.1 sit alongside AS 1668.2 for energy efficiency and ventilation-rate context, and ISO 9001, ISO 14001 and ISO 45001 frame the quality, environmental and OHS management systems that wrap the whole operation.

3. The air separation unit (ASU) — oxygen, nitrogen and argon by cryogenic distillation

The air separation unit is the heart of the industrial-gas industry and the most demanding single area for HVAC, because it is the one place where oxygen enrichment and oxygen depletion exist a few metres apart. An ASU takes in atmospheric air, compresses it, removes water and carbon dioxide, cools it to cryogenic temperature in a main heat exchanger, and distils it in the cold box into its components: oxygen (boiling point around −183 degree C), nitrogen (around −196 degree C) and argon (around −186 degree C). The cold box is a tall insulated structure packed with distillation columns; around it sit the air compressors, the molecular-sieve purification, the expansion turbines, the cryogenic pumps and the product vaporisers and storage tanks. BOC operates ASUs at Port Kembla, Westernport, Kwinana and Yarwun; Air Liquide Australia runs ASU production as well.

The dominant HVAC hazard around an ASU is twofold and simultaneous. On the oxygen side, the cold box, the liquid-oxygen pumps, the oxygen vaporisers and the oxygen compressor produce streams of high-purity oxygen, and any leak enriches the local atmosphere above 23.5 percent — the fire hazard. On the nitrogen and argon side, the same equipment produces high-purity nitrogen and argon, and any leak depletes the local atmosphere below 19.5 percent — the asphyxiation hazard. A cold-box site therefore needs fixed oxygen monitoring distributed through every occupiable area, alarming on both a high set-point (23.5 percent) and a low set-point (19.5 percent), with the sensors positioned according to where each gas would go: low and at breathing height for the cold heavy nitrogen and argon that settle into pits and pockets, and where oxygen would accumulate for the enrichment case.

The first rule of ASU HVAC is the elimination of confined-space pockets. Cold nitrogen and argon are denser than ambient air and flow downhill, filling pits, trenches, sumps, drain channels, the bottoms of enclosures and any low pocket, exactly the places a worker might enter for maintenance. The ventilation and ductwork design must avoid creating such pockets, must provide low-level extract to clear settled heavy gas, and must integrate with an AS 2865-style confined-space-entry regime and the oxygen-monitoring system so that no one enters a space that has gone outside the safe band. The cold-box enclosure, any analyser house, any compressor enclosure and any below-grade area gets specific attention.

Ductwork material around an ASU is 316L stainless throughout. Cryogenic-area air is cold and frequently moisture-laden — frost and condensation form on cold surfaces — and galvanised steel corrodes in that environment, so corrosion-resistant stainless is the default. Oxygen-service extract and any duct in an oxygen-enriched area must additionally be oxygen-clean: degreased, free of oil and hydrocarbon film, because in an enriched atmosphere a trace of oil is an ignition source. SBKJ fabricates the oxygen-clean, corrosion-resistant 316L stainless duct and the high-and-low extract topology that an ASU demands, using the SBAL-V auto duct line for rectangular sections and the SBFB-1500 spiral tubeformer for the round extract mains.

4. Oxygen enrichment — the fire hazard above 23.5 percent

Oxygen enrichment is one of the two killers, and it is the less intuitive of the pair, because oxygen itself does not burn — it makes everything else burn far more readily. Normal air is 20.9 percent oxygen. The safe upper limit for a breathing atmosphere is 23.5 percent, and the workplace and life-safety convention sets the high oxygen alarm there. Above 23.5 percent the consequences escalate quickly: the minimum ignition energy of fuels drops, the lower and upper flammable limits widen so that mixtures that were too lean or too rich to burn in air now burn, flame temperatures and burning rates climb, and the auto-ignition temperature of materials falls. Materials that are effectively non-combustible in air — many fabrics, some plastics, lubricating oils and greases, and even some metals in finely divided form — ignite from a small spark and burn violently in an enriched atmosphere. The classic and tragic mechanism is oxygen-saturated clothing: a worker whose overalls have been exposed to an oxygen leak becomes, in effect, wearing a fuel that a single spark or cigarette will turn into a fireball.

Oxygen enrichment occurs anywhere high-purity oxygen is produced, compressed, stored, decanted or filled: the cold-box oxygen section, the liquid-oxygen pump and vaporiser area, the oxygen compressor hall, the oxygen cylinder-filling bay and the medical-oxygen filling line. The HVAC controls are clear. Adequate ventilation dilutes any leak back toward 20.9 percent and prevents the local concentration climbing toward and past 23.5 percent. High-side oxygen monitoring, placed where enriched oxygen would accumulate, alarms at 23.5 percent and interlocks ventilation boost, audible-visual alarm and access control. Ductwork serving oxygen areas is oxygen-clean and smooth-bored to avoid trapping contamination. And ignition-source control around the enriched area is rigorous — which, combined with the conductive, bonded duct that prevents static accumulation, is part of why SBKJ supplies oxygen-clean 316L stainless ductwork rather than oily, hydrocarbon-contaminated galvanised work for this service.

The interaction between oxygen enrichment and the rest of the plant is important. Oxygen enrichment makes every other fire hazard worse: a hydrogen leak, an acetylene leak, a solvent vapour, a lubricant film — all become more dangerous in an oxygen-enriched atmosphere. This is why oxygen and flammable gases are kept apart, why the ASU oxygen section is separated from the acetylene and hydrogen plant, and why the HVAC zoning treats oxygen enrichment as a top-tier hazard in its own right, not a sub-case of general ventilation.

5. Nitrogen and argon asphyxiation — oxygen depletion below 19.5 percent

Nitrogen and argon asphyxiation is the other killer, and the deadlier of the two by history, because it gives no warning. Nitrogen makes up 78 percent of the air we breathe and is entirely non-toxic; argon is an inert noble gas; both are colourless, odourless, tasteless simple asphyxiants. They do not poison — they kill by displacing oxygen. The safe lower limit for breathing air is 19.5 percent oxygen, and the low oxygen alarm is set there. As the oxygen concentration falls, the effects worsen: impaired judgement and coordination in the high teens, rapid loss of consciousness in the low teens, and in a heavily nitrogen-displaced atmosphere — a space that has been purged with nitrogen, or the bottom of a pit into which cold argon has flowed — a single breath can cause collapse without warning, and death follows in minutes. The cruel feature is that the victim feels no air hunger, because the urge to breathe is driven by carbon dioxide build-up, not oxygen lack; the worker simply loses consciousness mid-task. Would-be rescuers who rush in without breathing apparatus become the next victims, which is why inert-gas asphyxiation incidents so often claim more than one life.

Oxygen depletion occurs anywhere nitrogen, argon or helium is produced, stored, vented, used for purging, or can leak: the ASU nitrogen and argon sections, the cold box, liquid-nitrogen and liquid-argon storage and pumping, cylinder-filling of nitrogen, argon and helium, gas-purged vessels and any enclosed space served by an inert-gas line. Cold liquid nitrogen and argon are an aggravated case, because as the liquid warms it expands enormously into gas — one volume of liquid nitrogen becomes hundreds of volumes of gas — and the cold gas is denser than ambient air, so it pools at low level exactly where people stand and enter.

The HVAC controls are ventilation, monitoring and the elimination of pockets. Ventilation — including low-level extract to clear settled cold heavy gas — dilutes a leak back toward 20.9 percent and prevents the local concentration falling toward 19.5 percent. Fixed oxygen monitoring at low level and at breathing height alarms at 19.5 percent and interlocks ventilation boost and access control. The design eliminates confined-space pockets where inert gas can stratify undetected, and integrates with a permit-to-work confined-space regime under AS 2865 principles, with supplied-air or self-contained breathing apparatus to AS/NZS 1715 and AS/NZS 1716 for any entry into a potentially depleted space. SBKJ ductwork for these areas is engineered with continuous fall, no horizontal dead-legs and dedicated low-level extract, so that no stratified inert layer can sit below the reach of the monitoring and the ventilation.

6. The cylinder-filling hall — dual-level extract, O2 monitoring and stratification

The cylinder-filling hall is where bulk gas becomes the cylinders that customers buy, and it is the area where stratification — the tendency of a gas to separate by density rather than mix evenly — most directly drives HVAC design. A typical hall fills oxygen, nitrogen, argon, helium, carbon dioxide and mixed industrial and specialty gas, often on multi-cylinder filling ramps and manifolds, with cylinders trucked in and out on pallets and stillages. Every filling connection, every manifold vent, every purge and every burst disc is a potential release point.

The governing fact is that a released gas does not stay mixed. It stratifies by density. Heavy gases sink and pool at low level: argon (about 1.4 times the density of air), carbon dioxide (about 1.5 times), and cold gas of any species while it is still cold. They collect in pits, trenches, drains, the wells around filling ramps, the spaces between stacked pallets and any low corner. Light gases rise and collect at high level: helium and hydrogen, which gather under the roof, in apex pockets, around purlins and ridge vents. Nitrogen, close to air in density, disperses more evenly but still depletes oxygen wherever it accumulates. A filling hall ventilated with a single high-level extract grille leaves a growing, invisible heavy-gas asphyxiation pool at the floor; a hall ventilated with a single low-level grille leaves a flammable or asphyxiant light-gas layer building under the roof. Either single-level design is a fatality waiting to happen.

The correct topology under AS 1668.2 and AS 4332 is dual-level extract. Low-level extract grilles and ductwork within roughly 300 to 500 mm of the floor capture heavy-gas pooling and settled cold gas. High-level extract at the roof apex captures buoyant light-gas accumulation and warm enriched air. The two paths together, sized to dilute the credible leak, hold the oxygen concentration inside the 19.5 to 23.5 percent band across the occupied volume and keep any flammable gas well below its LEL. Fixed oxygen monitoring is placed at both high and low level so that neither a floor pool nor a roof layer can develop undetected; where a flammable gas is filled (acetylene, hydrogen), flammable-gas detection and AS/NZS 60079 hazardous-area zoning are added, and the relevant zone gets Ex-rated equipment. The ductwork is run with continuous fall and no dead-legs, so that the extract genuinely reaches the places gas collects.

SBKJ fabricates both the low-level extract mains and the high-level apex collection ductwork in corrosion-resistant 316L stainless. The SBFB-1500 spiral tubeformer produces the round extract mains from 80 to 1500 mm; the SBAL-V auto duct line produces rectangular branches and plenums; the SBTF-1500/1602/2020 family produces trunk mains up to 2000 mm for large halls. Where a flammable gas is filled, the SB-ZF1500 adds a continuous conductive longitudinal weld so the duct is bonded and earthed for the AS/NZS 60079 zone.

7. Acetylene production and filling — the unstable, wide-range flammable

Acetylene (C2H2) is the most hazardous flammable gas handled in routine Australian industrial-gas filling, and its HVAC envelope is correspondingly severe. Two properties make it exceptional. First, its flammable range is extraordinarily wide — roughly 2.5 percent lower explosive limit, with the upper limit effectively reaching 100 percent — which means that above about 2.5 percent in air, almost any concentration will burn. Second, acetylene is thermodynamically unstable: under pressure, shock or heat it can decompose explosively even in the complete absence of air, the molecule tearing itself apart and releasing energy. This is why acetylene cannot simply be compressed into a cylinder like oxygen or nitrogen.

Acetylene is generated in one of two ways. The traditional route reacts calcium carbide with water in a generator, producing acetylene gas plus a calcium-hydroxide (slaked lime) slurry and carbide dust; the alternative route cracks hydrocarbons. The gas is then purified, dried, compressed in special multi-stage acetylene compressors, and dissolved into a solvent — acetone or DMF (dimethylformamide) — held in a porous mass inside the cylinder, so the acetylene is stored dissolved and stabilised rather than as free compressed gas. The porous mass plus solvent is what makes an acetylene cylinder safe.

The HVAC consequences run through the whole acetylene area. The generator hall, the purification area, the compressor house and the filling bay are classified as AS/NZS 60079.10.1 gas hazardous-area Zones — Zone 1 at the immediate filling, decanting and generator-vent points, Zone 2 in the surrounding hall — requiring Ex-rated fans, motors, instruments and lighting. Ventilation, biased to high-level extract because the buoyant case sends acetylene upward, must prevent any accumulation approaching the 2.5 percent LEL, with flammable-gas detection interlocked to ventilation boost and alarm. Ductwork must be conductive, continuously bonded and earthed to the building grid, because a static discharge in an acetylene atmosphere is an ignition source. The carbide-route generator adds an explosible-dust dimension under AS/NZS 60079.10.2 — calcium-carbide dust and lime dust — with dust capture and the associated bonding and explosion-protection considerations. And because acetone or DMF solvent is present, solvent-vapour control is part of the picture. SBKJ fabricates Ex-suitable, conductive, bonded 316L stainless ductwork with high-level extract for acetylene service, using the SBFB-1500 spiral tubeformer with the SB-ZF1500 continuous-weld option for a conductive, earthed spiral main.

8. Hydrogen production and filling — the buoyant wide-range flammable

Hydrogen (H2) is the gas of the moment in Australia, driven by the clean-energy economy, green-steel ambitions and hydrogen-mobility refuelling, and Coregas (Wesfarmers) and BOC are at the front of Australian hydrogen production and supply. Hydrogen is produced either by electrolysis — splitting water with electricity in an electrolyser, the green-hydrogen route — or by steam methane reforming (SMR), the conventional route, then purified, compressed to high pressure and filled into cylinders, tube trailers or refuelling systems.

Hydrogen’s HVAC envelope is defined by two properties. It has a wide flammable range — roughly 4 percent lower explosive limit to 75 percent upper limit — and a very low minimum ignition energy, so a small static spark can ignite a hydrogen-air mixture. And it is the lightest gas there is, intensely buoyant, so it rises rapidly and collects at the highest point of any enclosure: under the roof, in apex pockets, in ridge spaces and around high-level steelwork. The buoyancy is both a hazard and, handled correctly, a help: hydrogen disperses upward and outward quickly in the open, but indoors it accumulates at high level where it must be detected and vented.

The HVAC controls follow directly. Hydrogen areas — the electrolyser or reformer hall, the compression area, the filling and trailer-loading bays — are classified as AS/NZS 60079.10.1 gas hazardous-area Zones, with Ex-rated equipment throughout. Ventilation is biased strongly to high-level roof extract, because hydrogen goes up; roof venting and high-level extract at the apex prevent a flammable layer building under the roof, with the extract sized to hold any leak well below the 4 percent LEL. Flammable-gas (hydrogen) detection sits at high level and interlocks ventilation boost and alarm. Ductwork is conductive, continuously bonded and earthed, because hydrogen’s low ignition energy makes static control essential, and there must be no apex dead pocket where hydrogen can sit above the reach of the extract. SBKJ fabricates conductive, bonded 316L stainless high-level and roof extract for hydrogen service, with the SBFB-1500 spiral tubeformer and SB-ZF1500 continuous longitudinal weld giving a conductive, earthed main, and the SBTF-1500/1602/2020 family for trunk mains above 1500 mm.

9. CO2 and dry ice — heavier-than-air pooling and low-level extract

Carbon dioxide is the deceptively dangerous gas of the industrial-gas world, because it is not flammable, is familiar from everyday life, and is widely assumed to be harmless — yet it kills by both asphyxiation and direct physiological effect, and it pools invisibly at low level. CO2 is about 1.5 times denser than air, so it sinks and collects in pits, cool-rooms, dry-ice production rooms, cylinder-filling trenches, drains, cellars and stairwells. Australian CO2 is supplied by Supagas and BOC, much of it recovered food-grade from brewery and ethanol fermentation, and it is filled into cylinders and made into dry ice (solid CO2) by pressing the snow that forms when liquid CO2 is expanded.

CO2 differs from a simple asphyxiant in an important way: it is physiologically active well before it has displaced enough oxygen to trip a low-oxygen alarm. The SafeWork Australia workplace exposure standard is 5000 ppm (0.5 percent) as an eight-hour TWA and 30000 ppm (3 percent) short-term. At a few percent CO2 causes rapid breathing, headache, sweating and confusion; at higher concentrations it causes rapid collapse. Because the oxygen concentration may still read acceptable while the CO2 concentration is already dangerous, oxygen monitoring alone does not protect against CO2 — dedicated CO2 monitoring is required, placed at low level where the gas collects.

The single most important HVAC fact for CO2 is that extract must be low-level. Because CO2 collects at the floor, high-level extract is actively misleading — it draws fresh air across the top of a deepening invisible pool while the danger grows below. The correct topology is dedicated low-level extract within 300 to 500 mm of the floor in every CO2 area, fixed low-level CO2 monitoring, and additional capture at the dry-ice press, the snow horn and any point where liquid CO2 is expanded to solid, because sublimation there generates the densest, coldest gas. Cool-rooms and dry-ice stores need particular care, as they are enclosed, cold (which keeps CO2 dense) and easy to walk into. SBKJ fabricates the low-level CO2 extract spiral and the cool-room and dry-ice-room ductwork in corrosion-resistant 316L stainless, using the SBFB-1500 spiral tubeformer for the low-level mains and the SBAL-V for branches and plenums.

10. Medical gas — oxygen, nitrous oxide, medical air and N2O scavenging

Medical-gas production and filling adds a hygiene and regulatory layer on top of the physical-hazard layer, because the product goes into hospitals and patients. The medical gases are medical oxygen, nitrous oxide (N2O), medical air, and medical mixtures; in Australia they are produced and filled by BOC (BOC Healthcare) and Air Liquide (Air Liquide Healthcare), and they are regulated by the Therapeutic Goods Administration as therapeutic goods, with AS 2896 the reference standard for medical-gas systems.

Medical oxygen carries the full oxygen-enrichment fire hazard described earlier, with the added requirement of cleanliness — the filling environment, the ductwork and the handling all have to support a pharmaceutical-grade product. Medical air must be genuinely clean, dry and oil-free. But the gas that most sharply drives medical-gas HVAC is nitrous oxide. N2O has an extremely low workplace exposure standard — just 25 ppm as an eight-hour TWA — because chronic exposure is associated with reproductive and haematological effects; it is heavier than air and accumulates low; and it is a potent greenhouse gas, so uncontrolled venting is an environmental as well as an occupational problem.

The control strategy for N2O combines scavenging and dilution. Scavenging means capturing N2O at the point it is released — the filling head, the decanting connection, the manifold vent — through dedicated capture branches, rather than letting it disperse into the room air; this both protects the operator and reduces emissions. Low-level extract handles the residual heavier-than-air N2O, and fixed N2O monitoring confirms control against the 25 ppm standard. The whole medical-gas environment demands hygienic, cleanable, hermetically constructed ductwork — smooth-bored, continuously welded, with no crevices to harbour contamination — consistent with AS 2896 and TGA manufacturing expectations. SBKJ fabricates hermetically welded, cleanable 316L stainless scavenging and extract ductwork using the SBAL-V auto duct line and the SBSF-1525 longitudinal stitch welder, whose continuous TIG bead gives a crevice-free, decontaminable envelope suited to medical-gas service.

11. Specialty and calibration gas blending — the toxic and flammable trace mixtures

Specialty and calibration gas blending is the precision end of the industry, where small quantities of high-value gas mixtures are made to tight tolerances for laboratory, environmental-monitoring, medical, semiconductor, food-packaging and industrial-process use. Operators such as Coregas, BOC, Air Liquide and Supagas all run specialty-gas capability, and Air Products supplies specialty gases into Australian industry. A calibration-gas mixture might contain a few parts per million of a toxic or flammable component — carbon monoxide (CO, workplace exposure standard around 30 ppm), hydrogen sulphide, nitric oxide, nitrogen dioxide, methane, hydrogen, ammonia, sulphur dioxide and many others — balanced in nitrogen, air or argon.

The HVAC challenge in specialty blending is variety rather than volume. The blending area handles a wide range of gases, some toxic at low concentration, some flammable, some both, in a setting where a small leak of a high-concentration component cylinder before dilution could be significant. The ventilation strategy is well-ventilated, often hooded or cabinet-based handling at the blending and analysis stations, with the extract chosen for the densities and hazards of the gases in play, fixed monitoring appropriate to the toxic and flammable components present, and AS/NZS 60079 hazardous-area zoning where flammable components are handled. Because the gas mix changes, the design is conservative and flexible. SBKJ fabricates corrosion-resistant 316L stainless extract and cabinet ductwork for specialty-gas blending, using the SBAL-V for cabinet and bench extract and the SBFB-1500 for the round extract mains, with continuous-weld construction where a toxic or flammable component demands a hermetic, conductive envelope.

12. Cylinder, skid and manifold fabrication — weld-fume capture

Every industrial-gas operator runs a fabrication and maintenance workshop, because the industry is built on hardware: gas cylinders, cylinder pallets and stillages, filling skids, ramps, manifolds, vaporiser frames and the steelwork of the plant itself are fabricated, modified and repaired in-house or by specialist contractors. That workshop is a welding-fume environment, and it needs the same extract discipline as any metal-fabrication shop, with the added stainless-fume dimension because so much gas-industry hardware is stainless.

Welding generates a fume plume whose composition depends on the parent metal and the process. Carbon-steel welding produces iron oxide and, where present, manganese fume — manganese has a workplace exposure standard around 0.2 mg/m³, recently tightened because of neurological concern. Stainless welding produces hexavalent chromium (Cr VI), a carcinogen with a very low exposure standard around 0.05 mg/m³, and nickel fume. The control standard is on-tool and local exhaust ventilation to AS/NZS 4453 (welding-fume control) and the principles of AS 1668.2, capturing fume at the arc before it reaches the welder’s breathing zone, with 316L stainless extract mains running at 18 to 22 m/s transport velocity to a baghouse with appropriate filtration. Where stainless is welded routinely, dedicated capture and monitoring for Cr VI is warranted.

SBKJ fabricates the weld-fume extract for cylinder, skid and manifold workshops. The SBAL-III heavy-gauge auto duct line forms the 1.6 to 2.0 mm general extract mains; the SB-ZF1500 lays a continuous longitudinal weld for robust, fume-laden service; the SBLR-600 lock former produces the Pittsburgh and snap-lock seams on rectangular branches; and the SBPC1500 plasma cutter produces custom transitions, hood plates and stud plates. For fire-rated penetrations between the workshop and adjacent areas, the SBSF-1525 longitudinal stitch welder produces continuously welded 1.5 mm 316L fire-rated risers to AS 1530.4.

13. Hazardous-area classification — gas Zones, dust Zones and Ex equipment

Hazardous-area classification is the formal process that ties the whole plant’s flammable-gas and explosible-dust risk to the electrical equipment, the ductwork and the ventilation, and on an industrial-gas site it is dominated by AS/NZS 60079.10.1 (gas) with AS/NZS 60079.10.2 (dust) applying at the carbide-route acetylene generator. The classification exercise walks the plant and assigns, to every location where a flammable atmosphere can occur, a Zone reflecting how often and for how long that atmosphere is present.

For gas, Zone 0 is where a flammable-gas atmosphere is continuous or long-term (inside process equipment); Zone 1 is where it is likely in normal operation (the immediate vicinity of acetylene and hydrogen filling, decanting, manifold vents and generator vents); and Zone 2 is where it is unlikely and short-lived (the general hall around the Zone 1 envelopes). For dust, Zone 20 is continuous explosible-dust presence, Zone 21 occasional, and Zone 22 unlikely — relevant to calcium-carbide and lime dust around a carbide generator. The classification also identifies the relevant gas group and temperature class — hydrogen and acetylene fall into the most onerous gas groups because of their low ignition energy and wide flammable range — which drives the protection level of the equipment.

The consequences flow through the design. Electrical equipment in a zone — fans, motors, instruments, sensors, lighting, junction boxes — must carry the appropriate Ex protection (flameproof Ex d, increased safety Ex e, intrinsic safety Ex i, and others) for the zone, gas group and temperature class, selected and installed per the AS/NZS 60079 family and AS/NZS 3000, and inspected and maintained under AS/NZS 60079.17. Ductwork in a zone must be conductive throughout, continuously bonded with conductive flange gaskets, externally earthed to the building grid, and verified at commissioning with resistance below 1 ohm to ground at every section, so that no static charge can accumulate and discharge as an ignition source. Ventilation is itself a classification factor: adequate, reliable ventilation can reduce the extent or grade of a zone, which is one more reason the HVAC and the hazardous-area assessment must be designed together rather than in sequence. SBKJ fabricates the conductive, bonded, earthed 316L stainless ductwork that flammable-gas zones require, with the SB-ZF1500 continuous-weld option giving an electrically continuous spiral main.

14. WES and the oxygen-atmosphere dilution calculation

The dilution calculation is where the life-safety intent becomes a duct size and a fan duty. The principle of dilution ventilation is straightforward: a contaminant released into a space at some rate is diluted by the ventilation flow, and the steady-state concentration is the release rate divided by the ventilation rate (with a mixing-efficiency factor that accounts for imperfect mixing). For a toxic contaminant the target concentration is the workplace exposure standard; for a flammable gas it is a safe fraction of the LEL (commonly a small percentage of LEL for the alarm and a larger margin for the design); and for the oxygen atmosphere the targets are the two ends of the 19.5 to 23.5 percent band.

The Australian workplace exposure standards and atmospheric limits that drive these calculations on a gas site are specific. Oxygen: the safe range is 19.5 percent (low alarm, oxygen depletion, asphyxiation) to 23.5 percent (high alarm, oxygen enrichment, fire) — both ends are emphasised as THE killers. Carbon dioxide: 5000 ppm (0.5 percent) eight-hour TWA and 30000 ppm (3 percent) short-term. Nitrous oxide: 25 ppm eight-hour TWA. Carbon monoxide: around 30 ppm. Acetylene: a simple asphyxiant in bulk with a 2.5 percent LEL governing the flammable case. Hydrogen: a 4 percent LEL. Nitrogen, argon and helium: simple asphyxiants, governed not by a WES but by the oxygen concentration they produce by displacement. The practical consequence is that an oxygen-enrichment or oxygen-depletion calculation is framed around the credible leak — how much gas could plausibly escape, over what time, into what volume — and the ventilation is sized so that even that credible leak cannot push the local oxygen concentration outside the safe band, with monitoring as the independent backstop.

Two refinements matter on a gas site. First, mixing efficiency is rarely 1.0: a leak near the floor of a poorly mixed room produces a far higher local concentration than a perfectly mixed average would suggest, which is precisely why dual-level extract and the elimination of dead pockets matter, and why the design uses a conservative mixing factor. Second, the calculation is direction-aware for oxygen: the same room may need to defend against enrichment near the oxygen plant and depletion near the nitrogen plant, so the ventilation is sized for the worse of the two and the monitoring covers both. SBKJ engineers the ductwork — continuous fall, no dead-legs, dual-level extract, smooth-bore 316L — so that the as-built mixing behaviour matches the design assumptions and the calculated dilution is actually achieved in the field.

15. SBKJ machine line for industrial-gas HVAC duct fabrication

For an Australian fabricator or mechanical contractor serving the industrial-gas sector from Box Hill North VIC, the practical SBKJ machine envelope to cover the full duct demand — oxygen-clean, Ex-suitable, corrosion-resistant, dual-level — is built from the SBKJ Product Catalog 2026:

• SBAL-V with 316L stainless option — the backbone for oxygen-clean and corrosion-resistant rectangular duct: ASU and oxygen-area extract, medical-gas scavenging and extract, cylinder-hall branches and plenums, and cryogenic-area extract. Production envelope 0.7 to 1.6 mm in 304 and 316L stainless plus galvanised and aluminised, with stainless tooling, surface-protection film and TDF flange forming on stainless.
• SBAL-III — heavy-gauge 1.6 to 2.0 mm work for weld-fume extract mains in the cylinder, skid and manifold workshop, for compressor after-cooler and warm-regeneration runs, and for baghouse-inlet mains.
• SBSF-1525 — continuous TIG longitudinal stitch welder for the hermetic, cleanable envelope: medical-gas scavenging and oxygen-service duct, AS 2896 hygienic construction, and 250 degree / 2 hour fire-rated penetrations to AS 1530.4.
• SB-ZF1500 — in-line continuous longitudinal stitch welder for conductive, earthed spiral mains in acetylene and hydrogen hazardous-area service, and for hermetic medical-gas and oxygen mains 1000 to 1500 mm.
• SBFB-1500 — spiral tubeformer 80 to 1500 mm for the round high-and-low extract mains that this sector lives on: cylinder-hall dual-level extract, CO2 low-level extract, acetylene and hydrogen high-level extract, and ASU extract. The single most-used machine for gas-plant duct fabrication.
• SBPC1500 — plasma cutter for custom transitions, hood plates, refractory-anchor stud plates and bellows flanges in 316L and 309/310S high-temperature stainless, for compressor after-cooler and warm-regeneration geometry.
• SBLR-600 — lock former for Pittsburgh and snap-lock seams in rectangular duct, with heavy-gauge tooling for 1.2 mm 316L in oxygen-clean and hazardous-area service.
• SBTF-1500/1602/2020 — spiral trunk mains 1500 to 2000 mm for large cylinder-hall and generator-hall extract and for centralised extract trunks.

The combined fit delivers the production envelope to cover every duct requirement across every Australian industrial-gas operator — from BOC ASUs at Port Kembla, Westernport, Kwinana and Yarwun, through Air Liquide Australia ASU and medical-gas production, Coregas hydrogen and multi-gas at Port Kembla, Supagas CO2 and LPG multi-site, Renegade Gas / Speedgas LPG, and Air Products specialty gas — with 316L stainless as the common backbone because every chemistry on a gas site converges on oxygen-clean, corrosion-resistant, and conductive-where-needed stainless duct.

16. Commissioning, measurement and verification (M&V)

Commissioning industrial-gas HVAC is more demanding than commissioning ordinary industrial ventilation, because the ductwork is part of a life-safety system and the documentation has to prove it. The handover package includes pressure-test records (1.5x design pressure for 30 minutes per AS 4254 on every branch), earth-bonding verification at every flange and isolation point (resistance below 1 ohm to ground) for all hazardous-area duct, conductivity verification on every conductive flexible connection, NATA-certified airflow balance against the design schedule, verification that fixed oxygen monitoring alarms at both 19.5 percent and 23.5 percent and that the ventilation-boost and alarm interlocks operate, AS/NZS 60079.10 zone-classification documentation for the flammable-gas areas, AS 2896 documentation for medical-gas duct, and AS 4332 cylinder-store ventilation documentation. For medical-gas work the package also supports the TGA manufacturing record.

Ongoing monitoring runs on daily, weekly, monthly, quarterly and annual cycles. Daily: fixed oxygen and gas monitoring at the operator interface, continuous with alarms at the set-points; pressure differential across any collector; stack discharge monitoring per the EPA licence. Weekly: visual inspection of duct interior at access ports, condition of bonding straps and conductive flange gaskets, and confirmation that low-level extract grilles are clear. Monthly: airflow balance verification at key branches, isolation and damper actuation tests, and fan-vibration measurement. Quarterly: NATA-certified breathing-zone air sampling against the relevant WES — CO2 against 5000 ppm, N2O against 25 ppm, CO against 30 ppm, weld fume against its standards — with the data fed into the ISO 45001 OHS management system. Annual: full system pressure test, full earth-bonding re-verification on hazardous-area duct, inspection of any high-temperature section, and ATEX/Ex equipment inspection per AS/NZS 60079.17. SBKJ supplies every length with mill certificate, fabrication date, pressure-test record and bonding verification, the foundation paperwork the operator integrates into its compliance pack.

17. Standards reference table for industrial-gas HVAC

A consolidated reference of the standards and codes that govern industrial-gas HVAC ductwork in Australia, suitable for inclusion in a specification or handover document:

• AS 1668.1 — fire and smoke control in air-handling systems; fire-mode operation of gas-plant ductwork.
• AS 1668.2 — mechanical ventilation, required outdoor air, and the dilution framework for WES and oxygen-atmosphere control.
• AS/NZS 4254.1 and 4254.2 — sheet-metal and flexible duct construction across low, medium and high pressure ranges.
• AS 1530.4 — fire-resistance of building elements, including 250 degree / 2 hour fire-rated duct penetrations.
• AS/NZS 60079.10.1 — classification of gas hazardous areas (acetylene, hydrogen, flammable blending) into Zones 0, 1 and 2.
• AS/NZS 60079.10.2 — classification of dust hazardous areas (carbide and lime dust) into Zones 20, 21 and 22.
• AS/NZS 60079.0, .14, .17 and protection parts — Ex equipment requirements, installation design, and inspection and maintenance.
• AS 2896 — medical gas systems; cleanliness and integrity reference for medical-gas duct.
• AS 4332 — storage and handling of gases in cylinders; ventilation of cylinder stores and filling areas.
• AS/NZS 1596 — storage and handling of LPG; low-level ventilation and zoning for LPG filling.
• AS 3580 series — ambient-air sampling and analysis methods for stack-discharge and EPA-licence monitoring.
• AS/NZS 1715 and AS/NZS 1716 — selection, use, maintenance and specification of respiratory protective equipment.
• AS 4024 — safety of machinery; guarding and access on plant and fabrication equipment.
• AS/NZS 3000 — the Wiring Rules; electrical installation interfacing with AS/NZS 60079 in hazardous areas.
• AS 1210 — pressure vessels (context for columns, receivers and vessels in the plant).
• ADG Code and GHS — dangerous-goods transport of cylinders and bulk gas, and classification and labelling of hazardous chemicals.
• NCC Section J and ASHRAE 62.1 — energy efficiency and ventilation-rate context alongside AS 1668.2.
• NFPA 55 — compressed gases and cryogenic fluids code, the detailed US engineering reference.
• NFPA 68 and NFPA 69 — deflagration venting and explosion prevention, referenced for carbide-dust and flammable-gas explosion protection.
• ISO 9001, ISO 14001, ISO 45001 — quality, environmental and OHS management systems wrapping the operation.

18. Green Star, NABERS and energy — the ASU power and heat question

Sustainability and energy performance increasingly shape industrial-gas HVAC, because an air separation unit is one of the most energy-intensive pieces of process equipment in Australian industry — the main air compressors of a large ASU draw very large electrical loads continuously, and the economics of an ASU are dominated by electricity cost. The HVAC and the process heat-rejection are part of that energy picture. Compression generates heat that must be rejected through after-coolers and cooling systems; molecular-sieve purification regeneration uses heat; and the ventilation fans themselves consume energy around the clock.

Green Star (the Green Building Council of Australia rating) and NABERS (the National Australian Built Environment Rating System) apply to the buildings on a gas site — offices, control buildings, amenities — and increasingly to the industrial envelope where operators pursue corporate sustainability targets. The HVAC contributions are the familiar ones: efficient fans, variable-speed drives that match ventilation to actual demand rather than running flat out, heat recovery where compression heat can be usefully captured, well-sealed low-leakage ductwork that does not waste fan energy moving air that escapes, and ventilation control that maintains the life-safety dilution without over-ventilating. NCC Section J sets the energy-efficiency floor. The tension on a gas site is that life safety comes first — the ventilation must always deliver the dilution that keeps oxygen in the safe band — so energy optimisation is layered on top of an uncompromised safety baseline, typically through demand-responsive control that boosts on detection and trims to a safe minimum otherwise. SBKJ’s low-leakage, continuously sealed and welded 316L ductwork supports the energy case by minimising the leakage losses that otherwise force oversized fans.

19. Accessibility — DDA and AS 1428.1 on a gas site

Accessibility is a code obligation that applies to the occupiable and public-facing parts of an industrial-gas site, even though much of the plant is restricted operational area. The Disability Discrimination Act (DDA) and AS 1428.1 (design for access and mobility) govern the accessible paths, entries, amenities and facilities in the office, reception, control-building and amenities areas, and the HVAC must serve those spaces with compliant comfort ventilation and air conditioning. In practice this means the mechanical services to the front-of-house and amenities buildings are designed to ordinary commercial-comfort standards under AS 1668.2 and the NCC, with accessible-WC ventilation, tempered fresh air and comfort conditioning, separate from and not compromised by the process-hazard ventilation of the operational plant. The separation of the comfort-HVAC envelope from the life-safety process-ventilation envelope is itself good practice, and SBKJ supplies both the process-grade 316L stainless duct for the operational areas and the standard galvanised comfort duct for the office and amenities buildings.

20. Demand trend — hydrogen economy, medical gas and green steel

The Australian industrial-gas sector is on a growth trajectory driven by several converging trends, each of which feeds back to demand for new and upgraded gas-plant HVAC. The hydrogen economy is the headline: Australia’s ambitions in green hydrogen, hydrogen export and hydrogen mobility are driving new electrolyser plants, new hydrogen compression and filling, and new refuelling infrastructure, all of which require AS/NZS 60079.10.1 hazardous-area ventilation and conductive, bonded, high-level roof extract — Coregas and BOC are central to this build-out. Green steel is a second driver: the decarbonisation of steelmaking points toward hydrogen-based direct reduction, which would dramatically increase hydrogen demand and the associated production HVAC, while conventional steelmaking at Port Kembla continues to consume large tonnages of ASU oxygen. Medical gas is a third, steady driver: an ageing population and expanding healthcare infrastructure increase demand for medical oxygen, nitrous oxide and medical air, and for the clean, AS 2896-compliant production HVAC that medical-gas manufacture requires. Food and beverage CO2, specialty gases for electronics and environmental monitoring, and the continuing replacement of ageing first-generation plant HVAC round out the picture.

Every one of these trends translates into ductwork demand: new ASUs, new hydrogen plants, expanded cylinder-filling capacity, new medical-gas lines and replacement infrastructure all require oxygen-clean, Ex-suitable, corrosion-resistant 316L stainless ductwork with dual-level extract, fabricated to AS 4254 with continuous bonding and hermetic seam where required and documented through to commissioning. SBKJ’s 2026 catalog and engineering support is positioned to serve this growth across Australia — from the established ASU and medical-gas operations in NSW, VIC, WA, QLD and SA to the emerging hydrogen build-out led by Coregas and BOC.

21. Industry bodies and standards organisations

The Australian industrial-gas sector is supported by an active set of industry bodies and standards organisations. Gas Energy Australia (GEA) is the peak national body for the downstream gaseous-fuels industry, covering LPG, LNG and related gaseous fuels and the operators who distribute and fill them. ANZIG — the Australia and New Zealand Industrial Gas association — represents the industrial, medical and specialty-gas producers and fillers, and is the natural home for the safety codes of practice that govern oxygen, nitrogen, argon, acetylene, hydrogen, CO2 and medical-gas handling; the major operators BOC, Air Liquide, Coregas, Supagas and Air Products engage through it. Standards Australia is the national standards publisher responsible for the AS and AS/NZS standards referenced throughout this guide, working with the international IEC (for the 60079 series) and ISO (for the management-system standards). SafeWork Australia sets the model work-health-and-safety framework and the workplace exposure standards that drive the dilution calculations, with the state and territory WHS regulators enforcing on the ground. The Therapeutic Goods Administration regulates medical gas as a therapeutic good. The state EPAs license the plant discharges. Together these bodies frame the regulatory and good-practice environment within which gas-plant HVAC is designed, built and operated.

22. Competitive positioning — why an Australian fabricator wins gas-plant work

Industrial-gas HVAC is a specialist market that rewards fabricators who understand the hazards and can prove it in their documentation, and it punishes those who treat it as ordinary ducting. The barrier to entry is real: oxygen-clean fabrication discipline, 316L stainless capability, continuous-weld and hermetic construction, conductive and bonded hazardous-area duct, dual-level extract design literacy, and the commissioning-documentation rigour that an operator’s safety case and the regulators demand. A generic commercial fabricator without those capabilities cannot credibly tender for an ASU, a hydrogen plant or a medical-gas line, and an operator will not risk a life-safety ventilation system on an unproven supplier.

An Australian fabricator equipped with the right machine line and the right engineering knowledge holds several advantages. Local fabrication means short lead times, local stainless supply, local commissioning support and the ability to respond to the close-tolerance, change-prone nature of gas-plant projects. Australian-standards fluency — AS 1668, AS 4254, AS/NZS 60079, AS 2896, AS 4332 — means the documentation is right first time. And the relationship with the operators’ mechanical contractors is built on the ground, in person, at ARBS and on site. SBKJ’s role is to give that fabricator the production envelope — the SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600 and SBTF-1500/1602/2020 — to fabricate oxygen-clean, Ex-suitable, corrosion-resistant, dual-level gas-plant ductwork locally and competitively, from Box Hill North VIC to gas plants across the country.

23. Closing — SBKJ engineering support for Australian industrial gas

The Australian industrial-gas sector is the invisible utility under steelmaking, healthcare, food and beverage, manufacturing and the emerging clean-energy economy, and it is growing on the back of hydrogen, green steel, medical demand and food-grade CO2. Every new air separation unit, hydrogen plant, cylinder-filling expansion and medical-gas line is a life-safety ventilation problem first and an HVAC project second — because the same oxygen concentration that keeps a worker alive is dangerous in both directions, enrichment above 23.5 percent and depletion below 19.5 percent, and the ductwork is part of the system that holds it in the safe band. The SBKJ Group engineering team in Box Hill North VIC is positioned to support Australian fabricators and mechanical contractors serving this sector with machine supply, engineering documentation, commissioning support and ongoing technical advisory across every gas-plant process area described in this guide.

We will be exhibiting at ARBS 2026 in Sydney in May with the full SBKJ machine portfolio plus industrial-gas-specific reference samples covering oxygen-clean 316L envelope, conductive bonded hazardous-area spiral for acetylene and hydrogen, hermetic medical-gas scavenging duct, and low-level CO2 extract. Pre-show meetings with Australian gas-plant fabricators, mechanical contractors and operators are scheduled across the week.