Explosives, Ammonium Nitrate, ANFO, Emulsion, Mining Initiating Systems, Detonator & Dangerous-Goods Manufacturing HVAC Duct Guide

1. Why explosives and ammonium nitrate plant HVAC is its own engineering discipline

Explosives and ammonium nitrate manufacturing is one of the most tightly regulated heavy-process industries operating in Australia, and the building-services ventilation inside these plants carries safety consequences that are categorically different from a commercial tower, a hospital or even most industrial factories. Within a single integrated site — Orica’s Kooragang Island complex at Newcastle NSW, Dyno Nobel’s Moranbah ammonium nitrate plant in the Bowen Basin QLD, or CSBP Wesfarmers’ ammonia and AN operation at Kwinana WA — you can find an anhydrous ammonia plant venting trace vapour in one corner, a nitric acid plant emitting nitrogen oxides next door, an ammonium nitrate prill tower shedding oxidizer dust above, an emulsion matrix plant generating fuel-oil mist, an ANFO mixing line combining dry oxidizer prill with diesel, and — at the initiating-systems and detonator end of the chain — an area where the engineering design intent is the total absence of any ignition energy whatsoever. Each of these zones imposes a different demand on the ventilation: a different contaminant, a different exposure standard, a different ignition risk, a different hazardous-area classification and a different duct material. HVAC ductwork inside an explosives plant is not a commodity service. It is a process-safety problem that touches AS 2187.1 explosives storage, AS 4326 oxidizing-agent handling, AS/NZS 60079 hazardous-area classification, AS 1940 flammable-liquid control, AS 3780 corrosive-substance segregation, AS 3957 dust-hazard control, and the SafeWork Australia workplace exposure standards, all inside one secured perimeter.

This is, deliberately, a building-services document. It is about how you ventilate, dilute, extract from and protect these facilities — the air handling, fume dilution, dust extraction, hazardous-area duct classification and smoke control — in exactly the way a competent mechanical engineer would approach the ventilation of any regulated industrial plant. It does not describe how any explosive, oxidizer or initiating compound is made, mixed or formulated; those are matters for the process licensees and their regulators. The companies named here — Orica, Dyno Nobel and Incitec Pivot, CSBP Wesfarmers, Maxam Australia, AEL / AECI Australia, Johnex Explosives, Downer Blasting Services, BME, Hanwha and Quantum Explosives — are major, publicly listed or well-established operators running fully licensed and regulated Australian sites. The purpose of this guide is to give Australian fabricators and the mechanical contractors who serve these operators a clear engineering reference for the ductwork those sites need, and to set out how the SBKJ Group machine portfolio fabricates it.

Ammonium nitrate is the backbone product. Orica is the largest commercial explosives company in the world and its Kooragang Island plant at Newcastle is one of the largest ammonium nitrate manufacturing facilities in the Southern Hemisphere, supplying the Hunter Valley coal industry and beyond; Orica also operates at Yarwun in Gladstone QLD, at Gomia, in the Bontang joint venture, and runs a dedicated Technical Centre for research and quality work. Dyno Nobel, the explosives arm of Incitec Pivot, operates the Moranbah ammonium nitrate plant in the Bowen Basin serving the Queensland metallurgical-coal mines, plus operations at Mount Isa and the Gibson Island site at Brisbane. CSBP, the chemicals division of Wesfarmers, manufactures both ammonia and ammonium nitrate at Kwinana in Western Australia, supplying the iron-ore and gold sectors. Around these AN producers sits a layer of downstream and specialty explosives manufacturers and blasting-services companies: Maxam Australia, AEL / AECI Australia, Johnex Explosives at Kalgoorlie in the WA Goldfields, Downer Blasting Services, BME, Hanwha and Quantum Explosives. Behind all of them are the mining customers whose blast-hole demand drives the whole chain — BHP, Rio Tinto, Fortescue, Anglo American, Glencore and Newmont, across the Pilbara iron-ore province, the Bowen Basin coalfields and the Goldfields.

Across this entire sector, explosives-plant ductwork has to satisfy several simultaneous demands that rarely coincide elsewhere. It must be non-combustible and oxidizer-compatible, because ammonium nitrate is a UN Class 5.1 oxidizer and AS 4326 forbids any accumulation of oxidizer in contact with combustible material — no oil, no grease, no organic liners, no fibrous lagging on the wetted surface. It must be corrosion-resistant, because nitric acid plant NOx fume and acid mist destroy ordinary steel, and because ammonia and AN moisture are aggressive. It must be conductive and continuously bonded to earth, because dry oxidizer dust, fuel-oil mist and above all primary-explosive and detonator processes generate static, and a static spark is a credible ignition source. It must support proper dilution ventilation, because ammonia (WES 25 ppm TWA / 35 ppm STEL), nitrogen dioxide (3 ppm TWA / 5 ppm STEL), nitric acid (2 ppm), oil mist (5 mg/m³), carbon monoxide (30 ppm), diesel particulate and AN nuisance dust all have to be kept below their exposure standards at the breathing zone. And it must be secure, because AN and AN-rich materials are Security-Sensitive Ammonium Nitrate (SSAN) controlled, so every ventilation opening has to ventilate without breaching the physical security of the building. Each of these is manageable in isolation; together they explain why a generic commercial fabricator who treats an explosives plant as just another industrial job loses money on the first project and never returns for the second.

This guide walks every major process zone of an Australian explosives and AN facility and explains what changes about the ventilation and the ductwork, then closes with the SBKJ machine configuration that gives an Australian fabricator the production envelope to serve this market from Box Hill North VIC. We start with the regulatory backbone.

2. The Australian regulatory stack — AS 1668.2, AS 4254, AS/NZS 60079, AS 2187, AS 4326, AS 3780, AS 1940, AS 3957 and the WES inputs

Explosives and ammonium nitrate HVAC in Australia sits at the intersection of more than two dozen overlapping standards, codes and regulatory regimes. Missing any one of them invites a notice of non-compliance from SafeWork Australia, the state work-health-and-safety regulator, the state explosives or dangerous-goods authority, or the state environment protection authority. The stack splits into building-code compliance, occupational-health exposure compliance, hazardous-area electrical compliance, explosives and oxidizer-specific compliance, dangerous-goods storage compliance, dust-hazard compliance, and the international cross-references that Australian engineers and underwriters lean on where the AS suite is silent on a specific scenario.

2.1 AS 1668.2 — mechanical ventilation and the dilution backbone

AS 1668.2 is the umbrella mechanical-ventilation standard for Australia and the single most-used document for explosives-plant building ventilation. It sets the basis for general and dilution ventilation, and it is the standard that links a measured or credible contaminant emission to the airflow needed to keep the operator’s breathing-zone concentration below the relevant workplace exposure standard. For an ammonia plant, a nitric-acid area, an emulsion matrix room or an ANFO plant, AS 1668.2 dilution ventilation is the calculation that turns a contaminant generation rate and a target concentration (a fraction of the WES) into a required extract and make-up air rate. Critically, AS 1668.2 also governs make-up air: every cubic metre extracted from a process hood, a dust collector or a building purge must be replaced by tempered, filtered, controlled-velocity supply air, so that the process areas sit at a controlled pressure relationship to clean offices and laboratories and so that contaminant cannot back-migrate into occupied space.

2.2 AS 1668.1 — fire and smoke control in air-handling systems

AS 1668.1 governs the fire and smoke-control aspects of air-handling systems — fire and smoke dampers at fire-compartment boundaries, the shutdown and operation of air-handling plant in a fire, and the smoke-control philosophy for the building. In an explosives or AN facility this matters at every penetration between a process area and an adjacent control room, switchroom, office or evacuation route, and it interacts with the explosives-area requirement that, in some rooms, deliberately limits combustible content and ignition sources. AS 1668.1 fire dampers (with damper assemblies to AS 1682) and the duct fire-rating to AS 1530.4 together control how a fire or smoke event is contained.

2.3 AS 4254.1 and AS 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 to 1000 Pa and high to 2500 Pa. Most explosives-plant supply, general extract, dilution ventilation and fume/dust LEV sit inside the AS 4254 ranges. High-temperature dryer or granulator exhaust in its hot section may run beyond AS 4254 and require purpose-engineered construction, with AS 4254 picking up again downstream on the cool side. AS 4254 also sets the construction quality, sealing and pressure-test basis that the commissioning documentation relies on.

2.4 AS 1530.4 — fire-resistance of building elements

AS 1530.4 covers the fire-resistance testing of building elements, including fire-rated ductwork and penetrations through fire compartments. In an explosives facility this applies at every wall and floor penetration between a process area and an adjacent occupied or critical space — the penetration and any fire-rated duct must meet the fire-resistance level (FRL) called by the building’s NCC approval, with fire dampers to AS 1682 and the surrounding assembly meeting its rated integrity and insulation.

2.5 AS/NZS 60079.10.1 and 60079.10.2 — explosive-atmospheres classification

AS/NZS 60079 is the hazardous-area-classification standard, adopted from the IEC 60079 series, and it is the dominant electrical-safety driver across the plant. AS/NZS 60079.10.1 classifies gas/vapour atmospheres into Zone 0 (continuous), Zone 1 (likely in normal operation) and Zone 2 (unlikely, short duration); AS/NZS 60079.10.2 classifies combustible-dust atmospheres into Zone 20 (continuous), Zone 21 (likely in normal operation) and Zone 22 (unlikely, short duration). The older AS/NZS 61241 dust series remains referenced in some legacy installations. In an explosives and AN plant these zones appear at multiple locations: ammonia plant and fuel-oil/solvent areas (gas Zone 1/2, recognising ammonia’s wide flammable range of roughly 15–28% in air), emulsion oil-mist and ANFO dust areas, and AN handling where an oxidizer-plus-fuel or sensitised dust is credible. AS/NZS 60079 drives the selection of Ex-rated fans, motors, instruments, dampers and lighting in or near those zones, and it requires the ductwork itself to be conductive and continuously bonded to earth. Installation and inspection follow AS/NZS 60079.14 and AS/NZS 60079.17, and wiring and earthing follow AS/NZS 3000.

2.6 AS 2187.1 and AS 2187.2 — explosives storage, transport and use

AS 2187.1 (explosives — storage and transport) and AS 2187.2 (explosives — use of explosives) are the explosives-specific standards that overlay everything in the detonator, initiating-systems, magazine and dangerous-goods-store parts of the facility. AS 2187.1 governs the construction and ventilation of magazines and explosives stores, including the requirement to ventilate for temperature control and vapour dilution while maintaining security and segregation. In the initiating-systems and detonator-assembly areas, the explosives-safety philosophy — elimination of ignition sources, control of static, control of friction and impact — sets requirements that go beyond the general AS/NZS 60079 dust/gas framework, because the materials handled can be sensitive to very low ignition energies. For the HVAC engineer, AS 2187.1 is the document that, together with AS/NZS 60079, defines the no-ignition-energy envelope these rooms must meet.

2.7 AS 4326 — storage and handling of oxidizing agents (the AN rule)

AS 4326 (the storage and handling of oxidizing agents) is, for the AN side of the plant, the single most important document. Ammonium nitrate is a UN Class 5.1 oxidizer; it is not a fuel, but it powerfully supports the combustion of anything that is. The governing principle of AS 4326 is segregation of oxidizers from combustible and incompatible materials and the prevention of any accumulation of oxidizer in contact with combustibles. For ductwork that translates into hard rules: the wetted surface of AN-contact duct must be non-combustible (stainless or galvanised steel, not plastic, not lined with organic material); there must be no oil, grease or organic gasket residue on the AN-contact surface; there must be no fibrous internal acoustic lining; aluminium is avoided on AN-contact duct because AN can react with aluminium in the presence of moisture; and the duct must be smooth and self-draining so that hygroscopic AN cannot cake into a confined deposit. AS 4326 also drives the housekeeping regime — AN dust collection equipment and duct must be cleanable and kept clean.

2.8 AS 3780 — the storage and handling of corrosive substances

AS 3780 governs corrosive substances — the nitric acid, the acids used in laboratory and surface-treatment work, and other corrosives on site. It sets segregation, bunding and ventilation requirements that interact with the acid-fume extract design: corrosive-substance areas need extract to a neutralising scrubber, segregation from incompatible materials (including oxidizers and flammables), and corrosion-resistant construction throughout the wetted path. AS 3780, AS 4326 and AS 1940 together form the dangerous-goods segregation matrix that the building layout and the ventilation zoning have to respect.

2.9 AS 1940 — flammable and combustible liquids

AS 1940 governs the storage and handling of flammable and combustible liquids. In an explosives plant it applies to the fuel oil and diesel used in ANFO and emulsion, to the mineral oil in emulsion, and to any solvents used in accessory manufacture, laboratory work or maintenance. AS 1940 sets bunding, segregation, ventilation and ignition-control requirements around these liquids; for the HVAC engineer it drives the hazardous-area zoning around fuel and solvent handling (typically Zone 1 immediately above an open liquid surface and Zone 2 in the surrounds), the requirement for dedicated extract where vapour is generated, and the fire-load management of any duct that carries oil mist (the oil deposit inside an emulsion-plant duct is itself a fire load that has to be designed for cleaning).

2.10 AS 3957 — industrial dust controls and the dust-hazard analysis

AS 3957 covers industrial dust controls and is the Australian reference for the dust-hazard side of the plant. In an explosives and AN facility the dusts of interest are AN prill and granulation dust (an oxidizer), AN-plus-fuel dust in ANFO areas (an energetic mixture), emulsion solids, and any sensitised or contaminated dust. AS 3957 drives the dust-hazard analysis: at every dust-collection point the designer must establish the nature and hazard of the dust, the credible ignition sources, the accumulation and propagation paths, and the engineering controls. The output feeds the AS/NZS 60079.10.2 dust zoning and the deflagration-protection scheme. For the duct designer, AS 3957 forces smooth, self-draining, bonded, cleanable dust duct, minimal dead-legs, isolation between collector and building, and a documented housekeeping regime.

2.11 AS/NZS 2243.8 and AS/NZS 2243.9 — laboratory fume cupboards and recirculating cabinets

AS/NZS 2243.8 (fume cupboards) and AS/NZS 2243.9 (recirculating fume cabinets and laboratory ventilation considerations) govern the QC and technical-centre laboratories that every serious explosives producer operates — Orica’s Technical Centre is the leading Australian example. These standards set the face-velocity, containment, construction and exhaust requirements for fume cupboards, with the building ventilation under AS 1668.2. Where energetic or oxidizing materials are handled in the lab, the fume cupboards and their ducts are non-combustible internally, easily decontaminated, and bonded/conductive where energetic dust is present.

2.12 AS 4024, AS/NZS 3000, AS/NZS 1715 and AS/NZS 1716 — machinery, wiring and RPE

AS 4024 (safety of machinery) governs the guarding and safety of the air-moving and dust-collection plant. AS/NZS 3000 (the Wiring Rules) governs the electrical installation including the Ex aspects in hazardous areas, in conjunction with the AS/NZS 60079 series. AS/NZS 1715 (selection, use and maintenance of respiratory protective equipment) and AS/NZS 1716 (respiratory protective equipment) set the framework for the RPE that supplements engineering controls — for AN dust handling, ammonia work, acid work and energetic-dust handling, where powered air-purifying respirators and the appropriate cartridges are part of the control hierarchy alongside, never instead of, the ventilation.

2.13 The ADG Code, GHS, UN classes and NCC Section J — the regulatory frame

The Australian Dangerous Goods (ADG) Code governs the transport and, by reference, much of the classification of dangerous goods on site. The Globally Harmonised System (GHS) governs hazard classification and labelling of chemicals. The UN classification system places explosives in Class 1 and oxidizers, including ammonium nitrate, in Class 5.1 — the distinction that drives the AS 4326 oxidizer-handling rules. NCC Section J (energy efficiency) applies to the office, amenity and control-building parts of the site, where the HVAC has to meet the National Construction Code energy provisions and, increasingly, Green Star and NABERS targets. ASHRAE 62.1 is the international ventilation-for-acceptable-indoor-air-quality reference that aligns with AS 1668.2 for the occupied non-process spaces.

2.14 NFPA 68 and NFPA 69 — international deflagration cross-references

Where the AS suite does not give a complete design method for deflagration protection of dust-collection systems, Australian engineers and insurers cross-reference the US National Fire Protection Association standards NFPA 68 (standard on explosion protection by deflagration venting) and NFPA 69 (standard on explosion prevention systems). These are used as engineering references — not as adopted Australian standards — to size deflagration vent areas, to specify explosion-isolation devices, and to design inerting or suppression where a deflagration scenario is credible in an oxidizer-plus-fuel or sensitised-dust collection system. They sit alongside AS 3957 and the AS/NZS 60079 dust zoning, not in place of them.

2.15 ISO 9001, ISO 14001 and ISO 45001 — the management-system frame

ISO 9001 (quality), ISO 14001 (environment) and ISO 45001 (occupational health and safety) are the management-system standards that the major operators run, and they pull the HVAC documentation into the audit trail. ISO 45001 in particular ties the ventilation, the LEV maintenance records and the breathing-zone air-sampling data into the site OHS management system; ISO 14001 ties the scrubber and stack-emission performance into the environmental management system; and ISO 9001 underpins the fabrication and commissioning documentation that the duct fabricator supplies.

2.16 SafeWork Australia workplace exposure standards — the chemistry-driven sizing inputs

The SafeWork Australia workplace exposure standards (WES) are the regulatory inputs that drive dilution-ventilation rates, LEV capture velocity and ductwork sizing across the facility. The explosives-and-AN-relevant standards include:

• Ammonia (NH3): 25 ppm TWA / 35 ppm STEL. Anhydrous ammonia plant, refrigeration, AN precursor. Wide flammable range (~15–28% in air) and a pungent warning odour well below the WES.
• Nitric acid (HNO3): 2 ppm. Nitric acid plant, acid storage and loading.
• Nitrogen dioxide (NO2): 3 ppm TWA / 5 ppm STEL. Nitric acid plant tail gas, NOx fume, and a product of some thermal events. The dominant acid-gas sizing input.
• Oil mist (mineral): 5 mg/m³. Emulsion plant fuel-oil and mineral-oil mist around emulsifiers and matrix handling.
• Ammonium nitrate dust: handled as a nuisance/particulate and, critically, as a UN Class 5.1 oxidizer — the AS 4326 contamination-control rules dominate over a simple mass concentration.
• Diesel particulate matter: managed to the relevant exposure-limit/engineering-control value (ELV context) at ANFO fuel handling and mobile-plant areas.
• Carbon monoxide (CO): 30 ppm. Combustion plant, fired dryers, mobile plant.
• Carbon dioxide (CO2): 5000 ppm. Indoor-air-quality marker for occupied non-process spaces.
• Acid gases (HCl etc.): where present in surface-treatment or laboratory work, controlled to their respective WES with corrosion-resistant extract to scrubber.

Every dilution and LEV branch in the plant has to keep the operator’s breathing-zone air below the relevant WES, and where several contaminants are present together the additive-mixture rule applies and the ventilation is sized to the most demanding fraction. This is the calculation that drives capture velocity, transport velocity, branch sizing and main sizing across the whole facility, and it is set out in worked form in section 14.

3. Ammonium nitrate prill tower and granulation plant — oxidizer dust as the governing hazard

The ammonium nitrate prill tower and the granulation plant are the heart of an AN manufacturing site — Orica’s Kooragang Island plant, Dyno Nobel’s Moranbah plant and CSBP’s Kwinana plant all centre on AN solidification, whether by prilling (droplets of concentrated AN melt solidifying as they fall down a tower against a counter-current air stream) or by granulation (AN built up in layers on seed particles in a granulator drum or fluid bed). Both routes generate AN dust and fines, and both impose a ventilation problem dominated by a single fact: ammonium nitrate is a UN Class 5.1 oxidizer. It is not a fuel and it does not, by itself, behave like a conventional combustible dust — but it powerfully accelerates the combustion of anything combustible it contacts, it can decompose energetically under heat and confinement, and it is hygroscopic and mildly corrosive. The ventilation and dust-collection design follows from these properties.

The prill tower itself is, in effect, a very large air-handling device: a counter-current cooling-air stream is drawn up (or pushed down) through the falling prill curtain, and that air leaves carrying entrained AN fines. The tower offtake is a large-volume, dust-laden, warm and humid stream. The first engineering rule under AS 4326 is that everything the dust touches must be non-combustible — the offtake duct, the cyclones, the wet scrubber or bag filter, and every transition is steel (galvanised carbon steel is used on many dry prill-tower circuits, with 304/316L stainless preferred where moisture and corrosion are a concern). There is no organic liner, no fibrous acoustic lining, no oil or grease on the wetted surface, and no aluminium in contact with the AN. The second rule is cleanliness and self-drainage: AN is hygroscopic, so any cool, damp dead-leg becomes a caking point where AN builds a hard confined deposit; the duct is therefore run with smooth bends, minimal horizontal runs, generous cleaning access and falls back toward the collection point. The third rule is static control: dry AN dust handling generates static, so the entire offtake and collection train is bonded and earthed to below 1 ohm to ground.

The granulation plant adds drying, screening, crushing and recycle, each a dust source. Granulator, dryer and cooler off-gas is collected and de-dusted; screen decks, crushers and transfer points are hooded and put under local exhaust. The collected AN dust is typically recycled wet back into the AN solution rather than landfilled, which is both an economic and an environmental benefit and which keeps the oxidizer inside the controlled process. The dust-collection device of choice is frequently a wet scrubber for AN because water both captures the fines and returns them to process; where dry bag filtration is used, it is designed with the contamination-control, isolation and housekeeping discipline that AS 3957 and AS 4326 demand, and with deflagration protection referenced to NFPA 68/69 because a sensitised or contaminated AN dust is a credible energetic hazard.

The dryer section deserves specific attention because it combines AN dust with heat. Drying air is heated (commonly by an indirect or direct fired heater); the dryer exhaust carries AN fines at elevated temperature. The exhaust duct in its hot section is steel rated for the temperature, transitioning to the standard cool-side construction downstream; the heater and its controls are subject to the fired-equipment safety regime; and the interaction of AN dust with combustion products is managed so that no oxidizer-plus-fuel accumulation can form inside the exhaust path. Across the whole prill and granulation plant, the AN dust offtake and collection system is the largest single ventilation system in the AN plant, and it is fabricated almost entirely from steel duct (the SBFB-1500 spiral tubeformer for the round mains, the SBAL-V or SBAL-III auto duct lines for rectangular transitions and hoods, the SBPC1500 plasma cutter for cyclone and scrubber-inlet cones) on the non-combustible, smooth, bonded, self-draining basis described above.

4. Ammonia plant and nitric acid plant — anhydrous ammonia vapour and NOx fume dilution

Upstream of AN sits the ammonia plant and the nitric acid plant — the two precursor processes that, combined, produce ammonium nitrate. CSBP at Kwinana manufactures ammonia on site; Orica and Dyno Nobel operate ammonia handling and nitric acid plants at their integrated sites; Incitec Pivot’s Gibson Island operation has a long history in ammonia-based products. From the HVAC engineer’s point of view these are two distinct ventilation problems: anhydrous ammonia vapour dilution on the ammonia side, and nitrogen-oxide (NOx) acid-fume extraction on the nitric acid side.

Anhydrous ammonia has a workplace exposure standard of 25 ppm TWA and 35 ppm STEL, and it has a sharp warning odour detectable well below those levels — which is a useful safety feature but not a substitute for engineering control. The ammonia compressor house, pump areas and any enclosed ammonia-handling building are ventilated under AS 1668.2 so that the credible continuous leakage from flanges, pump seals, valve stems and instrument connections is diluted below the 25 ppm TWA at the breathing zone, with general extract configured to capture both high-level and low-level (a liquid ammonia release flashes and behaves initially as a cold, dense cloud even though ammonia gas is lighter than air). On top of the continuous dilution sits a detection-initiated high-rate purge: ammonia detectors are set with a pre-alarm well below 25 ppm and a high-alarm at the 35 ppm STEL, and on alarm the supply and extract fans step up to an emergency air-change rate and the event is signalled to the control room and tied into the plant emergency shutdown. Because ammonia has a wide flammable range (~15–28% in air), a major-release scenario can place parts of the building in a gas hazardous-area zone under AS/NZS 60079.10.1, which drives Ex-rated fan motors and electrical equipment in those areas. The extract duct is non-combustible (galvanised or 316L stainless to AS 4254), and it discharges clear of air intakes, occupied areas and ignition sources.

The nitric acid plant presents the opposite chemistry: an aggressively corrosive, oxidising acid-gas stream. Nitric acid plant tail gas and the local fume around absorption columns, acid storage tanks, sample points and acid-loading arms contain nitrogen oxides — principally NO and the brown, toxic NO2. The governing exposure standards are nitric acid 2 ppm, NO2 3 ppm TWA / 5 ppm STEL. Acid-fume extract is captured at the source (loading arms, sample stations, tank vents) at 0.5–1.0 m/s across the source and carried at 10–15 m/s transport velocity — acid mist is corrosive but not abrasive, so high transport velocity is unnecessary and merely adds fan energy and erosion of any protective lining. The material selection is driven by corrosion: 316L stainless for general acid-fume extract, and for the most aggressive wet-acid mist a fibre-reinforced plastic (FRP) duct with a vinyl-ester corrosion barrier or a fluoropolymer-lined duct, specified with a conductive veil where it sits in a hazardous area so it can be bonded. Drainage falls are built into every run so condensed acid drains back toward the scrubber sump rather than pooling and concentrating in the duct. The extract terminates at a wet alkaline (caustic) packed-tower scrubber that neutralises NOx and acid mist before stack discharge under the site EPA licence, with the scrubber and stack performance tied into the ISO 14001 environmental management system. The plant-wide ventilation keeps the ammonia and nitric-acid streams strictly segregated — an oxidising acid stream and an alkaline ammonia stream must never share extract.

5. Emulsion explosive plant — fuel-oil mist, mineral oil and surfactant aerosol

Emulsion explosives are the dominant bulk product for modern mining, and emulsion matrix plants are operated both by the AN majors and by the specialty manufacturers — Maxam, AEL / AECI, BME, Hanwha and others run emulsion technology, and the AN producers manufacture emulsion and emulsion matrix for their own blasting-services divisions. An emulsion explosive is a water-in-oil emulsion: a concentrated oxidiser-salt solution dispersed as fine droplets in a continuous fuel/mineral-oil phase, stabilised by a surfactant emulsifier. This guide does not address the formulation; the ventilation interest is in the airborne hazard the process generates, which is dominated by oil mist.

Around the emulsifier, the matrix mixers, the hot-matrix transfer points and the packaging or bulk-loading stations, the characteristic airborne contaminant is a fine mineral-oil and fuel-oil mist, accompanied by surfactant aerosol and warm water vapour. The relevant exposure standard is oil mist 5 mg/m³. The ventilation response is local exhaust capture of the oil mist at each source — capture hoods over the emulsifier and mixers, slot or canopy capture at hot-matrix transfer, and enclosing extract at packaging — sized for a capture velocity that draws the warm, buoyant oil-mist plume away from the operator (typically 0.5–1.0 m/s at the source, higher where the plume is hot and rising). The extract is carried in non-combustible duct to a mist-eliminator or coalescing filter that removes the oil before discharge.

Two features distinguish emulsion-plant extract from ordinary ventilation. First, the oil deposit inside the duct is a fire load. Oil mist condenses on the duct wall and accumulates; an oil-coated duct is a combustible deposit and a fire-spread path, exactly the scenario AS 1940 is concerned with. The duct is therefore designed to be cleaned — smooth bore, generous access doors, minimal horizontal dead runs, and a documented cleaning regime — and the material is non-combustible steel (304/316L stainless preferred for cleanability and corrosion, galvanised acceptable in drier areas). Second, the emulsion process combines an oxidiser solution with a fuel; while the matrix itself is handled as a process material, the ventilation system treats the surrounding area on the basis that an oxidiser-plus-fuel environment is energetic, so ignition-source control applies: the duct is bonded and earthed, fans serving the area are spark-resistant where the zoning requires, and electrical equipment in the hazardous-area zones is Ex-rated. AS 1940 governs the bulk fuel-oil and mineral-oil storage that feeds the plant, with bunding, segregation and vapour-area zoning around the storage and the dosing points. The SBSF-1525 continuous-weld seam is used where the oil-mist duct must be hermetic and where the oil-fire-load containment demands a leak-tight envelope.

6. ANFO mixing — dry oxidizer prill, fuel oil and ignition-source control

ANFO — the porous-prill-plus-fuel-oil bulk explosive that has been the workhorse of open-cut mining for decades — is produced and handled in ANFO plants and at mine-site mixing facilities operated by the AN producers’ blasting-services arms and by the specialty manufacturers, including Johnex at Kalgoorlie, Downer Blasting Services, Quantum and others serving the Pilbara, Bowen Basin and Goldfields mines of BHP, Rio Tinto, Fortescue, Anglo American, Glencore and Newmont. The process combines porous ammonium nitrate prill with a controlled dose of diesel or fuel oil. Again, this guide does not address the proportions or the process; the ventilation interest is the airborne environment, which is a dry, dusty combination of AN dust and hydrocarbon — the defining oxidiser-plus-fuel dust hazard.

The dust sources are the AN prill handling (bag or bulk-bag discharge, conveying, hopper transfer, augering) and the fuel-oil dosing and mixing points. AN prill handling generates AN dust — an oxidizer — and the mixing stage produces a fuel-coated AN dust that is an energetic mixture. The ventilation response is local exhaust dust capture at every prill-handling and mixing point, in non-combustible bonded steel duct, carried at 18–22 m/s transport velocity to a dust collector. Because the dust is an oxidiser-plus-fuel mixture, the dust-collection and ventilation system is engineered against deflagration: isolation between the collector and the building (referenced to NFPA 69), deflagration venting on the collector where credible (referenced to NFPA 68), and rigorous contamination control under AS 4326 and AS 3957. Ignition-source control is the dominant theme — the entire dust system is bonded and earthed (static discharge is a realistic ignition source for an oxidiser-plus-fuel dust), fans serving the dusty areas are spark-resistant construction (referenced to AMCA 99 Type B/C), and electrical equipment in the dust hazardous-area zones (Zone 21 at handling points, Zone 22 in surrounds) is Ex-rated for the dust group and temperature class under AS/NZS 60079.10.2. The diesel and fuel-oil storage and dosing is controlled under AS 1940. Diesel particulate from mobile plant in enclosed ANFO loading areas is managed to the relevant engineering-control value with dilution ventilation and, where needed, tail-pipe capture. As with AN dust generally, the duct is smooth, self-draining and accessible so that no confined energetic-dust deposit can build up, and the housekeeping regime keeps it clean.

7. Initiating systems, detonators and blasting-accessory areas — the zero-ignition-energy envelope

The initiating-systems end of the explosives industry — detonator assembly, the handling of primary explosives and energetic compositions, and the manufacture of blasting accessories such as detonating cord, boosters and shock-tube assemblies — is the most hazardous environment in the entire chain and the one where the ventilation design philosophy changes most fundamentally. In the AN, ammonia, nitric acid, emulsion and ANFO areas the design controls a contaminant to below an exposure standard and controls ignition sources to a credible-risk level. In a detonator or primary-explosive area, the materials can be sensitive to extremely low ignition energies — energy levels far below what a person feels as a static shock — and the design intent is therefore the total elimination of ignition energy. There is no permissible spark, no permissible static discharge, no permissible hot surface and no permissible friction or impact source. The ventilation system has to be engineered to that standard.

These areas are classified under AS 2187.1 (explosives storage and handling) in combination with AS/NZS 60079 where a flammable dust or vapour atmosphere is also present, and they are designed and operated under the explosives licensee’s detailed safety case. For the HVAC engineer the requirements crystallise into a small number of absolute rules. The ductwork is fully conductive and continuously bonded to a dedicated earth grid, with conductive flange gaskets and external bonding straps at every joint and verified resistance to ground below 1 ohm at every section. Flexible connections, where unavoidable, are specifically conductive (anti-static) flexible duct with bonded end collars and a verified end-to-end resistance — never a plain plastic flexible. Capture hoods, grilles, dampers and any in-airstream hardware are non-sparking material. Any fan in or serving the area is spark-resistant construction (referenced internationally to AMCA 99 Type B or Type C, where the impeller is non-ferrous or the geometry guarantees the wheel cannot strike the housing to produce a spark). Electrical equipment is intrinsically safe (Ex i) for instrument and control circuits, with power equipment kept out of the room wherever possible; what remains is Ex-rated to the correct gas/dust group and temperature class, installed and inspected under AS/NZS 60079.14 and AS/NZS 60079.17, and earthed under AS/NZS 3000.

Static-electricity control is the defining discipline. Everything in the room — the floor, the operators, the work surfaces, the equipment and the ductwork — is referenced to a single equipotential earth so that there is no potential difference anywhere that could drive a discharge. Relative humidity is frequently held in a controlled band because dry air promotes static accumulation; the HVAC system therefore does double duty, providing both the contaminant control and the humidity control that the electrostatic-discharge (ESD) regime requires. The ventilation provides enough capture to remove fine energetic dust from the operator’s breathing zone, but it does so through a system that is, end to end, a no-spark, no-static, fully bonded envelope. The duct is laid out to avoid any internal accumulation of energetic dust — smooth bends, no dead-legs, no rough internal seams, and accessible cleaning — because a confined accumulation of energetic dust is itself a hazard regardless of ignition source. In short, the detonator and initiating-systems area is where conductive/anti-static duct, spark-resistant fans, intrinsically safe instrumentation, controlled humidity and meticulous bonding all come together as a single integrated design, and it is the area where a fabricator’s ability to produce a genuinely conductive, hermetic, bonded stainless duct envelope is most critical.

8. SSAN secure handling — Security-Sensitive Ammonium Nitrate and the ventilation envelope

Security-Sensitive Ammonium Nitrate (SSAN) is the regulatory category that covers ammonium nitrate and AN-rich mixtures controlled because of their potential for misuse. Following a national Council of Australian Governments agreement, SSAN is regulated through the state explosives and dangerous-goods authorities, and the controls govern who may manufacture, store, transport, supply and access AN, with obligations for physical security, access control, inventory accounting and reporting. Orica, Dyno Nobel and CSBP all manufacture and store AN inside SSAN-controlled security envelopes, and the specialty manufacturers and blasting-services companies handle SSAN-controlled material under the same regime.

SSAN affects HVAC design in three concrete ways, all of which sit at the intersection of ventilation engineering and physical security. First, the building envelope: SSAN-controlled rooms, AN storage and secure handling areas sit inside a secured perimeter, so every ventilation opening — intake louvre, extract penetration, relief vent, dust-collector inlet or outlet — must be designed so that it ventilates the space without breaching its physical-security rating. Vents are screened, barred, baffled or ducted through secure transitions so that the airflow path cannot become an access path. The mechanical engineer works the ventilation openings jointly with the security engineer rather than cutting penetrations to suit the duct route. Second, equipment access: the ventilation and dust-collection plant and ductwork serving SSAN areas fall inside the access-controlled zone, so filter changes, collector servicing, fan maintenance and duct cleaning are all managed under the site security plan and access-control procedures — which the duct layout has to accommodate with maintainable, accessible equipment positions. Third, the AS 4326 oxidiser-handling rules apply throughout, so the duct is non-combustible, smooth, bonded and self-draining as for any AN-contact service. The practical effect is that HVAC for SSAN areas is never a standalone services package; it is designed as one element of the integrated dangerous-goods and security design, and the duct fabricator delivers an envelope that supports both the ventilation function and the security and contamination-control requirements.

9. Magazine and dangerous-goods store ventilation — AS 2187.1 temperature control and vapour dilution

Explosives magazines and dangerous-goods stores are governed by AS 2187.1 and the relevant state explosives or dangerous-goods regulator, and their ventilation objectives are quite different from process areas. A magazine is a storage structure, not a process room, so the ventilation is there to control temperature, prevent condensation and dilute any low-level vapour — not to capture a process emission. Many explosive products and accessories degrade, lose stability or shorten their safe storage life at elevated temperature, and emulsion and some nitrate products carry storage-temperature limits, so limiting the internal temperature rise of a magazine in the Australian climate — particularly in the Pilbara, the Goldfields, Mount Isa and the tropical north — is a genuine safety function.

The default approach is passive cross-ventilation: screened, weatherproof, vermin-proof and security-rated vents at high and low level allow natural airflow to limit temperature build-up and clear any vapour, without any mechanical plant and therefore without any ignition source. The vents are the critical detail — they must ventilate while preserving the security rating of the magazine (sized, screened and baffled so they cannot provide access), preserving the structure’s integrity, and excluding rain, vermin and wind-driven debris. Where passive ventilation is inadequate — a hotter climate, a larger store, a product that emits solvent or decomposition vapour, or a store where vapour dilution must be assured — mechanical ventilation is added, and where it is, every element suits the hazard: the fan and ductwork are non-sparking and bonded, any electrical device is Ex-rated to the area classification, and the system is designed so it cannot itself introduce an ignition source. AS 1940 and AS 3780 add ventilation and segregation requirements where flammable or corrosive dangerous goods are co-stored, and the dangerous-goods segregation matrix (oxidisers, flammables, corrosives, explosives kept apart) drives the layout. The SSAN and explosives-security regimes mean magazine vents are also part of the secured perimeter, so the same vent-versus-security balance described in section 8 applies. Fabrication of magazine and DG-store ventilation components — weatherproof high/low-level vent terminals, security-compatible non-sparking transitions, and any mechanical-ventilation duct — is straightforward steel work, but it has to be done to the non-combustible, non-sparking, bonded standard the rest of the facility demands.

10. Hazardous-area classification of ductwork and fans — Zones, Ex equipment and spark-resistant fans

Hazardous-area classification is the thread that runs through every process zone in the plant, and it deserves a consolidated treatment because it governs the selection of every fan and every piece of electrical equipment, and the construction of every duct, in or near a classified area. The classification is established under AS/NZS 60079.10.1 for flammable gas and vapour and AS/NZS 60079.10.2 for combustible and energetic dust, with AS 2187.1 overlaying the explosives-specific areas.

On the gas/vapour side, the zones are Zone 0 (explosive atmosphere present continuously or for long periods), Zone 1 (likely in normal operation) and Zone 2 (unlikely in normal operation and, if it occurs, only briefly). In an explosives plant the gas/vapour zones appear around the ammonia plant (recognising ammonia’s wide flammable range), around fuel-oil and diesel handling, around solvent use, and immediately above open flammable-liquid surfaces (typically Zone 1) with the surrounds as Zone 2. On the dust side, the zones are Zone 20 (combustible dust cloud present continuously or for long periods, typically the interior of equipment), Zone 21 (likely in normal operation, such as the immediate area of an AN handling or ANFO mixing point) and Zone 22 (unlikely and short-duration, the general room around the equipment). The detonator and initiating-systems areas are treated to the no-ignition-energy standard described in section 7.

Once the zones are mapped, the equipment selection follows. Fans serving a classified area are specified for spark-resistant construction, referenced internationally to AMCA 99: Type A uses non-sparking material for all parts in the airstream; Type B uses a non-ferrous impeller running in a housing fitted with a non-sparking rub ring; Type C is configured so that the impeller and the housing cannot come into contact in any credible misalignment, eliminating the rub-spark path. The choice between them depends on whether the conveyed stream, the surrounding atmosphere, or both, are flammable or energetic. Fan motors and any in-duct or adjacent electrical devices — dampers, actuators, sensors, transmitters, lighting — are Ex-rated: intrinsically safe (Ex i) for low-energy instrument circuits, and flameproof (Ex d) or increased-safety (Ex e) for power, selected to the correct gas group (for example the group covering ammonia) or dust group and to a temperature class below the ignition temperature of the dust or vapour. Installation follows AS/NZS 60079.14, periodic inspection follows AS/NZS 60079.17, and the electrical installation overall complies with AS/NZS 3000.

The ductwork itself, in any dust or energetic-vapour hazardous area, is conductive throughout and continuously bonded to earth. Metal duct (304/316L stainless as the default, galvanised where acceptable) is bonded across every flange with conductive gaskets and external bonding straps; conductive (anti-static) flexible connections are used where flexibility is unavoidable, with verified continuity; and where non-metallic FRP duct is required for corrosion service in a hazardous area, it incorporates a conductive carbon veil that is bonded. Everything is referenced to a common equipotential earth so that there is no potential difference between the duct, the fan, the equipment and the structure that could drive a static discharge. Commissioning verifies the bonding resistance to ground (below 1 ohm at every section) and the continuity of every conductive flexible connection, and the verification records form part of the hazardous-area dossier and the ISO 45001 safety-management documentation. This consolidated hazardous-area discipline — spark-resistant fans, Ex-rated electrical equipment, conductive bonded duct, common earth — is what separates competent explosives-plant ventilation from ordinary industrial ventilation, and it applies, in graded form, from the relatively benign general-extract areas right up to the zero-ignition-energy detonator rooms.

11. Oxidizer dust collection and deflagration control — AS 3957, grounding, bonding and NFPA 68/69 concepts

Dust collection is the largest single category of ventilation in an AN, ANFO and emulsion facility, and it is where the oxidiser nature of the dust and the energetic potential of contaminated or oxidiser-plus-fuel mixtures come together. AS 3957 is the Australian dust-controls reference and the starting point is a dust-hazard analysis: at every collection point the designer establishes what the dust is (pure AN oxidiser, AN-plus-fuel energetic mixture, emulsion solids, or a potentially contaminated stream), what the credible ignition sources are, where the dust can accumulate and how an event could propagate, and what engineering controls apply. The output feeds the AS/NZS 60079.10.2 dust zoning and the deflagration-protection scheme.

For pure AN dust, the dominant control is contamination prevention under AS 4326: keep the oxidiser away from fuel, keep the duct and collector clean, and use wet collection where practical so the AN is captured in water and returned to process. AN is not a conventional combustible dust, but a dust-collection system handling it must still be engineered against energetic-event scenarios for three reasons set out earlier — intentional or incidental oxidiser-plus-fuel mixtures (ANFO, emulsion), contamination of the AN stream by oil, grease or combustible site dust, and the capacity of AN itself to decompose energetically under heat and confinement. The protective philosophy is therefore the same one used for genuine combustible dust: rigorous housekeeping and contamination control; isolation between the collector and the process building so an event cannot propagate back along the duct; and, where a deflagration scenario is credible (above all in ANFO and emulsion dust circuits), engineered deflagration protection referenced internationally to NFPA 68 (deflagration venting — relieving an over-pressure to a safe location through a vent of calculated area) and NFPA 69 (explosion prevention by isolation, suppression or inerting). These are engineering cross-references, not adopted Australian standards, and they are applied alongside AS 3957 and the AS/NZS 60079 dust zoning.

Grounding and bonding is mandatory throughout, because static discharge is a realistic ignition source for any sensitised or oxidiser-plus-fuel dust. Every duct section, every collector, every flexible connection and every item of plant in the dust circuit is bonded to a common earth grid, with resistance to ground verified below 1 ohm at every section at commissioning and re-verified on a regular cycle. The collector itself is selected for the duty: a wet scrubber for AN where water capture and recycle suit the process; a carefully managed dry collector with deflagration venting and explosion isolation where dry collection is required; and, for energetic-dust circuits, a collector positioned outdoors or in a dedicated structure with its vent path directed to a safe location and an isolation device (chemical-suppression, flap valve or equivalent) between it and the building. The duct between the source and the collector is the highest-risk segment: it is non-combustible, smooth, self-draining, run with minimal bends and no horizontal dead-legs (so no confined energetic-dust deposit can build), continuously bonded, and accessible for cleaning. Transport velocity is held at 18–22 m/s so fine dust stays entrained and does not settle into a deposit. This is the construction the SBFB-1500 spiral tubeformer and the SBSF-1525 / SB-ZF1500 continuous-weld machines are configured to deliver.

12. Acid and NOx fume extraction — material selection, scrubbing and drainage

Acid and NOx fume extraction is the corrosion-driven counterpart to dust collection, and although it has been touched on in the nitric-acid-plant section it warrants a consolidated treatment because acid fume appears in several places — the nitric acid plant, acid storage and loading, any surface-treatment or pickling operation, and the QC laboratory — and the material-selection logic is common to all of them. The contaminants are nitric acid (WES 2 ppm), nitrogen dioxide (3 ppm TWA / 5 ppm STEL) and, where present, other acid gases such as hydrochloric and sulphuric acid mist. These streams are aggressively corrosive and, in the case of NOx, oxidising as well, so the material has to resist both corrosion and oxidation.

The material hierarchy is: 316L stainless steel for general acid-fume extract, which resists NOx and most acid mist and gives a durable, cleanable, bondable duct; FRP (fibre-reinforced plastic) with a vinyl-ester or furan corrosion-barrier resin for the most aggressive wet-acid mist streams, where even 316L is attacked over time; and fluoropolymer-lined duct for the worst combinations. Where FRP is used in a hazardous area it is specified with a conductive carbon veil so the duct can be bonded and earthed — an un-bonded non-metallic duct in a hazardous area is not acceptable. AS 3780 governs the corrosive-substance handling that generates these streams, and it drives the segregation (acids kept apart from oxidisers, flammables and incompatibles) that the extract zoning has to respect — an oxidising acid stream must never share extract with an alkaline ammonia stream or with a combustible-dust stream.

The design rules for acid-fume extract are distinct from dust extract. Capture velocity at the source (loading arms, sample points, tank vents, bath surfaces) is 0.5–1.0 m/s — enough to capture the fume without entraining excessive room air. Transport velocity is 10–15 m/s, lower than for dust because acid mist is corrosive but not abrasive and there is no dropout-of-particulate concern; running it faster merely wastes fan energy and erodes any protective lining. Drainage falls are built into every run so that condensed acid drains back toward the scrubber sump rather than pooling in low points where it concentrates and accelerates corrosion. The extract terminates at a wet alkaline (caustic) packed-tower scrubber that neutralises the acid and NOx before stack discharge under the site EPA licence, with the scrubber and stack performance monitored and tied into the ISO 14001 environmental management system. Fabrication of the stainless acid-fume duct uses the SBAL-V auto duct line and the SBFB-1500 spiral, with the SBSF-1525 continuous TIG weld giving the hermetic, leak-tight seam that corrosive-fume service requires, and the SBPC1500 plasma cutter producing the scrubber-inlet cones and the custom transitions.

13. Laboratory and technical-centre fume cupboards — AS/NZS 2243.8 and AS/NZS 2243.9

Every serious explosives producer operates quality-control and research laboratories, and Orica’s Technical Centre is the leading Australian example of a dedicated explosives research and quality facility. In these laboratories AN, emulsion samples, initiating compositions and a range of analytical reagents and acids are handled at small scale — for quality testing, formulation development and failure analysis. The laboratory ventilation is governed by AS/NZS 2243.8 (fume cupboards) and AS/NZS 2243.9 (recirculating fume cabinets and laboratory ventilation considerations), with the building mechanical ventilation under AS 1668.2 and the broader laboratory-design considerations under AS/NZS 2982.

Fume cupboards are the primary engineering control. Each is specified with a face velocity in the standard band (commonly around 0.5 m/s, confirmed against the AS/NZS 2243.8 containment and face-velocity tests), and ducted — individually, or in compatible manifolds where the chemistries allow — in corrosion-resistant duct (316L stainless for general work, FRP for dedicated acid work) to dedicated exhaust fans that discharge clear of air intakes and occupied areas. Because some of the materials handled are oxidisers, energetic, or acid-forming, the fume cupboards used for that work are non-combustible internally, easily decontaminated, and — where energetic dust is handled — bonded, with the associated ductwork conductive and earthed. Specialised work (for example any perchloric-acid procedure, if present) requires dedicated wash-down fume cupboards and wash-down ducts that prevent the accumulation of hazardous residues.

The laboratory HVAC is interlocked and pressure-controlled. Loss of fume-cupboard extract is alarmed; the room supply air tracks the extract so that the room pressure relationships are maintained; and the laboratory is held at negative pressure relative to clean corridors and offices so that any contaminant migrates inward to the extract, not outward to occupied space. The combination of AS/NZS 2243.8/.9 fume-cupboard performance, AS 1668.2 room ventilation, corrosion-resistant and (where needed) conductive duct, and the interlocked pressure regime gives the technical-centre laboratory the same engineered-containment standard as the process plant, at laboratory scale. Fabrication of the stainless and FRP fume-cupboard exhaust collars and manifold duct is straightforward but must meet the same non-combustible, smooth, decontaminable, bonded-where-required standard as the rest of the facility.

14. Dilution ventilation and WES — the AS 1668.2 sizing calculation

Dilution ventilation is the calculation that underpins the general ventilation of the ammonia plant, the nitric-acid area, the emulsion and ANFO buildings, and any space where a contaminant is released into the room air rather than captured entirely at source. The principle in AS 1668.2 is simple: the airflow supplied to dilute a contaminant must be enough to keep the steady-state room concentration below a chosen design fraction of the workplace exposure standard, accounting for imperfect mixing. In its basic steady-state form the required dilution airflow Q (in cubic metres per second) is the contaminant generation rate G (in the same mass or volume units per second) divided by the allowable concentration C (the design fraction of the WES, expressed as a volume or mass fraction), multiplied by a mixing factor K that accounts for incomplete mixing and the position of the release relative to the extract.

The inputs come straight from the WES table. For ammonia the design concentration is a fraction of the 25 ppm TWA (commonly a conservative fraction, with the detection system set to act well before 25 ppm and to high-alarm at the 35 ppm STEL). For nitrogen dioxide it is a fraction of the 3 ppm TWA / 5 ppm STEL. For oil mist it is a fraction of 5 mg/m³; for carbon monoxide a fraction of 30 ppm; for AN dust the AS 4326 contamination-control rules dominate over a simple concentration target. Where several contaminants are present together — for example acid gases in the nitric-acid area, or oil mist plus vapour in the emulsion plant — the additive-mixture rule applies: the sum of the ratios of each contaminant’s concentration to its own exposure standard must remain below one, so the ventilation is sized to the combination, not to any single contaminant in isolation.

Dilution ventilation is the control of last resort, not first choice. The hierarchy in every process area is: contain and capture the contaminant at source with local exhaust (the AN dust hoods, the acid-fume capture, the oil-mist hoods, the detonator-area capture) so that as little as possible escapes into the room; then dilute the residual with general ventilation to keep the room background below the WES; then, only where engineering controls cannot fully achieve the standard, supplement with respiratory protective equipment under AS/NZS 1715/1716. The make-up air for both the captured and the diluted flows is tempered, filtered and delivered under AS 1668.2 so that the building pressure relationships are maintained — process areas at a controlled relationship to clean areas, hazardous areas arranged so contaminant cannot migrate to occupied space, and the whole air balance documented. The dilution calculation, the capture-velocity selection and the transport-velocity selection together define the duct sizing across the facility, and they are the engineering core of the commissioning and verification described in section 16.

15. Material selection — why galvanised is restricted and what replaces it

Galvanised carbon steel is the workhorse of ordinary HVAC fabrication, and across commercial towers, schools and most factories hot-dip-galvanised sheet to AS/NZS 4254 is the right answer. In an explosives and AN plant its use is restricted, and for several streams it is the wrong answer. The material logic is driven by four demands that rarely coincide elsewhere: oxidiser compatibility, corrosion resistance, conductivity for bonding, and cleanability.

15.1 Galvanised carbon steel — where it is and is not acceptable

Galvanised carbon steel remains acceptable for general supply air, general (non-contaminant) extract, and some dry AN prill-tower and granulation dust circuits where corrosion is not a concern and the duct is kept clean and bonded. It is restricted or unsuitable for: corrosive acid and NOx fume (zinc is attacked by acids); wet AN service (zinc corrodes in the presence of AN moisture); and the most safety-critical bonded circuits, where the surface oxide on galvanising can raise contact resistance at flange joints and complicate the verified-low-resistance bonding that combustible-dust and detonator-area service demands. Where galvanised is used in a bonded dust circuit, the bonding is achieved with conductive gaskets and external straps and verified, rather than relying on the galvanised surface itself.

15.2 304 and 316L stainless steel — the explosives-plant workhorse

Stainless steel is the dominant material across the facility. 304 stainless serves many AN-contact and general corrosion-resistant duties; 316L stainless (Cr 16–18%, Ni 10–14%, Mo 2–3%, C below 0.03%) is preferred wherever corrosion, cleanability or bonding is critical — AN oxidiser dust where moisture is present, ammonia extract, NOx acid fume (general acid service), emulsion oil-mist duct, detonator-area conductive duct, and laboratory fume-cupboard exhaust. Stainless gives the non-combustible, smooth, decontaminable, consistently bondable envelope that AS 4326, AS 3780 and the hazardous-area rules require. It is fabricated on the SBAL-V auto duct line with the stainless option for rectangular duct, the SBFB-1500 spiral tubeformer for round duct, and the SBSF-1525 / SB-ZF1500 continuous-weld machines for hermetic seams.

15.3 FRP fibre-reinforced plastic — aggressive acid-mist service

For the most aggressive wet-acid mist streams, where even 316L is attacked over time, FRP with a vinyl-ester or furan corrosion-barrier resin is the preferred material. FRP duct is built to AS/NZS 4254 with manufacturer-specific pressure and temperature ratings; in any hazardous area it is specified with a conductive carbon veil so that it can be bonded and earthed, because an un-bonded non-metallic duct in a classified area is not acceptable. FRP is the natural choice for nitric-acid-plant wet-mist extract and for dedicated acid fume cupboards in the laboratory.

15.4 What is excluded — aluminium, organic liners and fibrous lagging

Three materials are deliberately excluded from AN-contact and energetic-dust service. Aluminium is avoided on AN-contact duct because AN can react with aluminium in the presence of moisture. Organic and plastic internal liners are excluded from oxidiser-contact and energetic-dust duct under AS 4326, because they introduce combustible material into contact with an oxidiser. Fibrous internal acoustic lining is excluded from these streams for the same reason and because it traps dust and cannot be decontaminated. Where acoustic attenuation is required on an oxidiser or energetic-dust system, it is achieved with non-fibrous, non-combustible means or external treatment, never with an exposed fibrous internal liner.

16. Velocity and sizing — transport and capture for explosives-plant dust and fume

Explosives-plant HVAC sizing is dominated by two velocity calculations — capture velocity at the source and transport velocity in the main — both driven by the contaminant, its particle size and density, and the practical limits of fan capacity.

Capture velocity is the air velocity at the source needed to draw the contaminant into the hood faster than buoyancy, mechanical disturbance and cross-drafts can carry it past the operator. For AN dust handling and ANFO mixing points, 0.5–1.0 m/s at the operator interface is the practical range; for emulsion oil-mist hoods, 0.5–1.0 m/s (higher where the plume is hot and rising); for acid baths, sample points and loading arms, 0.5–1.0 m/s across the source; for laboratory fume cupboards, the standard face velocity around 0.5 m/s confirmed by the AS/NZS 2243.8 tests; and in detonator and initiating-systems areas, enough capture to clear fine energetic dust from the breathing zone within the constraints of the no-ignition-energy design.

Transport velocity is the minimum velocity in the main needed to keep the contaminant entrained without dropout. For AN dust, ANFO dust and energetic dust, 18–22 m/s is the standard range — below about 15 m/s, fine dust begins to settle at horizontal runs and elbows and builds a deposit, which for an oxidiser or oxidiser-plus-fuel dust is exactly the confined accumulation the design must prevent. For acid and NOx fume, 10–15 m/s is sufficient (corrosive but not abrasive, no particulate dropout concern). For ammonia and general vapour dilution extract, lower velocities are adequate. Each branch is sized at its design transport velocity, and the main is sized for the simultaneous load of its branches at their design coincidence factor, with spiral round duct preferred for dust and fume because its streamlined cross-section holds velocity through bends without the dropout pockets that flat-panelled rectangular duct creates.

17. The SBKJ machine line for explosives and AN duct fabrication

Fabricating explosives-plant ductwork to the standard set out in this guide requires the right machine fit, the right process discipline and the right documentation. The SBKJ Product Catalog 2026 covers the full envelope. SBKJ does not publish dimensional tolerances or pricing in this guide; specifications are confirmed per project with the SBKJ Box Hill North VIC engineering team.

SBAL-V — the auto duct line (V-method coil line) with the stainless option, forming galvanised and 304/316L stainless rectangular duct with TDF flange. It is the core machine for the bulk of supply, general extract and the 304/316L stainless oxidiser-dust, ammonia-extract and acid-fume rectangular duct that the plant needs.

SBAL-III — the heavy-gauge auto duct line for thicker work, used for heavy transitions, large hoods, scrubber-inlet sections and the heavier-gauge extract mains downstream of high-temperature sources.

SBSF-1525 — the longitudinal stitch welder that lays a continuous TIG bead on the lock-seam joint, giving the hermetic, leak-tight, fully conductive seam that corrosive NOx acid-fume duct, oil-mist emulsion duct and bonded energetic-dust circuits require.

SB-ZF1500 — the longitudinal stitch welder that runs in-line with the SBFB-1500 spiral former to deposit a continuous TIG bead along the formed spiral on larger trunk mains, for hermetic, double-bonded round duct.

SBFB-1500 — the spiral tubeformer (flange-forming / TDF capable) producing spiral round duct from 80 mm to 1500 mm diameter in galvanised, aluminised or stainless. It is the single most-used machine for explosives-plant duct, producing the streamlined round dust and fume mains that AN dust, ANFO dust, oil-mist and acid-fume transport demand.

SBPC1500 — the auto plasma cutting machine, handling stainless plate up to 25 mm, used to cut cyclone and scrubber-inlet cones, custom transitions, hood geometry and high-temperature transitions from CAD cut files with a clean kerf and minimal heat-affected zone.

SBSF-1525 also serves as the sheet feeder and shear stage ahead of forming, squaring and cutting stainless and galvanised blanks to length for the hood, transition and fitting work that the dust and fume systems need; paired with the SBFB-1500 spiral output it gives the round-duct-plus-transition capability that is the backbone of dust and fume fabrication.

SBLR-600 — the rollformer / Pittsburgh lock former producing the Pittsburgh and snap-lock longitudinal seams for rectangular duct construction, with heavy-gauge tooling for stainless oxidiser and acid-fume service ahead of continuous welding on the SBSF-1525 where a hermetic seam is required.

SBTF-1500/1602/2020 — the TDF flange and spiral-trunk family, producing TDF flange and spiral for the largest trunk mains up to 2000 mm diameter, used for centralised dust-collection trunks and large building dilution-extract mains.

The combined fit — SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600 and SBTF-1500/1602/2020 — gives an Australian fabricator the production envelope to cover every duct requirement across an explosives or AN facility, in galvanised, aluminised and 304/316L stainless, with hermetic continuous-weld seams and conductive bonded construction where the hazardous-area and oxidiser-handling rules demand it.

18. Australian operator deep dives

18.1 Orica — Kooragang Island NSW, Yarwun QLD, Gomia, Bontang JV and the Technical Centre

Orica is the world’s largest commercial explosives company and the anchor operator of the Australian sector. Its Kooragang Island plant at Newcastle NSW is one of the largest ammonium nitrate manufacturing complexes in the Southern Hemisphere, integrating ammonia handling, nitric acid production and AN manufacture to supply the Hunter Valley coal industry and beyond. Orica also operates at Yarwun in Gladstone QLD, at Gomia, in the Bontang joint venture, and runs a dedicated Technical Centre for research, formulation and quality work. From the HVAC standpoint a site like Kooragang Island is the full stack in one place: anhydrous ammonia vapour dilution and detection-initiated purge, nitric-acid-plant NOx fume extract to caustic scrubber, AN prill-tower and granulation oxidiser-dust collection (the largest single ventilation system on site), emulsion and bulk-product handling, SSAN-controlled secure storage and handling, magazine ventilation, and the Technical Centre laboratory fume-cupboard suite. The duct fabric is overwhelmingly steel — galvanised for dry general duties, 304/316L stainless for oxidiser-moisture, ammonia and acid service — with FRP on the most aggressive acid mist, all built to the non-combustible, smooth, bonded, self-draining standard. The SBKJ fit centres on the SBFB-1500 spiral for the dust and fume mains, the SBAL-V/SBAL-III for hoods and rectangular runs, the SBSF-1525/SB-ZF1500 for hermetic acid and energetic-dust seams, and the SBPC1500 for scrubber and cyclone transitions.

18.2 Dyno Nobel / Incitec Pivot — Moranbah QLD, Mount Isa and Gibson Island

Dyno Nobel, the explosives business of Incitec Pivot, operates the Moranbah ammonium nitrate plant in the Bowen Basin, purpose-positioned to serve the Queensland metallurgical-coal mines, together with operations at Mount Isa and the Gibson Island site at Brisbane (long associated with ammonia-based manufacturing). The Moranbah plant’s ventilation profile mirrors the AN-manufacturing stack: ammonia and nitric-acid precursor ventilation, AN prill/granulation oxidiser-dust collection, and the bulk-product and SSAN-controlled handling that feeds the Bowen Basin blasting-services operation. The remote inland location and the Queensland climate put a premium on magazine and storage temperature control. The SBKJ machine fit is the same dust-and-fume-centred envelope — SBFB-1500 spiral mains, SBAL-V/SBAL-III rectangular work, SBSF-1525/SB-ZF1500 hermetic seams, SBPC1500 transitions — fabricated in galvanised and 304/316L stainless to the oxidiser-handling and hazardous-area standard.

18.3 CSBP Wesfarmers — Kwinana WA ammonia and ammonium nitrate

CSBP, the chemicals division of Wesfarmers, manufactures both ammonia and ammonium nitrate at Kwinana in the Western Australian industrial strip south of Perth, supplying the iron-ore producers of the Pilbara and the gold sector of the Goldfields. Because CSBP makes ammonia on site, the ammonia-plant ventilation — compressor-house dilution, detection-initiated purge, wide-flammable-range gas zoning — is a prominent part of the stack, alongside the nitric-acid NOx extract and the AN prill/granulation oxidiser-dust collection. The Kwinana location, on a major industrial estate, brings the full NCC, EPA and dangerous-goods regulatory frame to bear. The SBKJ fit again centres on stainless and galvanised steel duct fabricated on the SBFB-1500, SBAL-V/SBAL-III, SBSF-1525/SB-ZF1500 and SBPC1500, with FRP for the aggressive acid mist.

18.4 Specialty manufacturers and blasting-services — Maxam, AEL/AECI, Johnex, Downer, BME, Hanwha, Quantum

Around the AN majors sits a layer of specialty explosives manufacturers and blasting-services companies. Maxam Australia and AEL / AECI Australia bring international explosives technology to the Australian market. Johnex Explosives manufactures at Kalgoorlie in the heart of the WA Goldfields, serving the gold mines directly. Downer Blasting Services, BME, Hanwha and Quantum Explosives operate manufacturing, emulsion and ANFO, and on-bench mixing services across the mining regions. These operations span emulsion matrix plants (oil-mist-dominated ventilation), ANFO plants (dry oxidiser-plus-fuel dust ventilation), accessory and initiating-systems handling (zero-ignition-energy areas), and SSAN-controlled storage. The common thread is the same: non-combustible, conductive, corrosion-resistant, smooth, bonded ductwork fabricated to the AS 4326, AS 2187.1, AS 1940 and AS/NZS 60079 standard, which is exactly the envelope the SBKJ machine line is configured to produce for an Australian fabricator serving these customers.

18.5 The mining customers — BHP, Rio Tinto, Fortescue, Anglo American, Glencore, Newmont

The demand that drives the whole explosives sector comes from the mines. BHP, Rio Tinto and Fortescue dominate the Pilbara iron-ore province; Anglo American, BHP and Glencore are major operators in the Bowen Basin coalfields; Newmont and a wide field of gold producers operate across the Goldfields. These miners consume the AN, emulsion and ANFO produced by Orica, Dyno Nobel, CSBP and the specialty manufacturers, and many operate on-site or near-site mixing and storage facilities — bulk emulsion plants, ANFO mixing facilities, magazines and dangerous-goods stores — that need the same explosives-grade ventilation as the manufacturing plants, at mine-site scale and often in the remote Pilbara, Bowen Basin and Goldfields environment. The HVAC and dust-control engineering described in this guide therefore extends from the major manufacturing complexes out to the mine-site explosives infrastructure, all of it built on the same non-combustible, conductive, bonded, corrosion-resistant duct standard.

19. Commissioning, monitoring and AS 1668.2 measurement and verification

Commissioning explosives-plant ductwork is more demanding than commissioning conventional industrial HVAC, because the documentation has to satisfy not only the building and mechanical standards but the explosives, oxidiser, dangerous-goods and hazardous-area regimes as well. The handover pack includes pressure-test records (typically 1.5x design pressure for 30 minutes per AS 4254 on every branch); AS 1668.2 airflow measurement and verification — a NATA-certified balance of every supply, extract, dilution and LEV branch against the design schedule, confirming that capture velocities, transport velocities and dilution rates achieve the design intent and keep breathing-zone concentrations below the WES; earth-bonding verification at every flange, isolation device and conductive flexible connection (resistance below 1 ohm to ground); the AS/NZS 60079.10 hazardous-area-classification dossier with the electrical-equipment and fan selection recorded against each zone; the AS 3957 dust-hazard analysis and the deflagration-protection scheme; the AS 4326 oxidiser-handling and contamination-control documentation; and, for the explosives areas, the AS 2187.1 documentation tying the ventilation into the licensee’s safety case.

Ongoing monitoring runs on daily, weekly, monthly, quarterly and annual cycles. Daily: gas detection at the ammonia plant (continuous, pre-alarm well below 25 ppm, high-alarm at 35 ppm) and NOx detection at the nitric-acid area, pressure differential across each dust collector and scrubber, and stack particulate or emission monitoring under the EPA licence. Weekly: visual inspection of duct interiors at access ports for AN caking, energetic-dust accumulation or oil-mist build-up; condition of bonding straps and conductive flange gaskets; condition of conductive flexible connections. Monthly: airflow balance verification at key branches, isolation-device function test, fan condition and vibration. Quarterly: NATA-certified breathing-zone air sampling against the WES for every operator-occupied area, with the data fed into the ISO 45001 OHS management system. Annual: full system pressure test, full bonding-resistance re-verification, scrubber media and dust-collector servicing, high-temperature-section inspection, and Ex-equipment inspection per AS/NZS 60079.17. The measurement-and-verification regime is what proves the ventilation continues to do its job over the life of the plant, and it is the reason the duct must be smooth, accessible and cleanable from the day it is installed.

20. Standards reference table

The following table consolidates the standards and codes referenced in this guide and where each applies in an explosives or ammonium nitrate facility.

Standard / code	Scope	Where it applies in the facility
AS 1668.1	Fire and smoke control in air-handling systems	Fire/smoke dampers and AHU control at fire-compartment boundaries
AS 1668.2	Mechanical ventilation, dilution and make-up air	Ammonia, nitric-acid, emulsion, ANFO building ventilation and WES dilution
AS 4254.1 / 4254.2	Sheet-metal and flexible duct construction	All normal-pressure supply, extract and LEV ductwork
AS 1530.4	Fire-resistance of building elements	Fire-rated duct penetrations between process and occupied areas
AS/NZS 60079.10.1	Gas/vapour hazardous-area classification	Ammonia plant, fuel-oil and solvent areas (Zone 0/1/2)
AS/NZS 60079.10.2	Dust hazardous-area classification	AN handling, ANFO mixing, energetic-dust areas (Zone 20/21/22)
AS/NZS 61241	Electrical apparatus for combustible-dust atmospheres (legacy)	Legacy dust-area electrical installations
AS 2187.1	Explosives — storage and transport	Magazines, DG stores, detonator and initiating-systems areas
AS 2187.2	Explosives — use of explosives	Use and on-bench context for mine-site facilities
AS 4326	Storage and handling of oxidizing agents	All ammonium nitrate oxidiser-contact ductwork and dust collection
AS 3780	Storage and handling of corrosive substances	Nitric acid, acid storage, laboratory and surface-treatment areas
AS 1940	Flammable and combustible liquids	Fuel oil, diesel, mineral oil and solvent handling (emulsion, ANFO)
AS 3957	Industrial dust controls	Dust-hazard analysis and dust-collection design
AS/NZS 2243.8 / 2243.9	Laboratory fume cupboards and recirculating cabinets	QC and technical-centre laboratories
AS/NZS 2982	Laboratory design and construction (ventilation)	Technical-centre and QC laboratory ventilation
AS 4024	Safety of machinery	Fans, dust collectors and air-moving plant guarding
AS/NZS 3000	Electrical installations (Wiring Rules)	All electrical installation including Ex in hazardous areas
AS/NZS 1715 / 1716	Respiratory protective equipment	RPE for AN dust, ammonia, acid and energetic-dust work
ADG Code	Australian Dangerous Goods Code	Classification and transport of dangerous goods on site
GHS	Globally Harmonised System	Chemical hazard classification and labelling
UN Class 1 / Class 5.1	Explosives / oxidizers classification	Explosives areas (Class 1); ammonium nitrate (Class 5.1 oxidizer)
NCC Section J	Energy efficiency	Office, amenity and control-building HVAC
ASHRAE 62.1	Ventilation for acceptable indoor air quality	Occupied non-process spaces (cross-reference to AS 1668.2)
ISO 9001 / 14001 / 45001	Quality / environment / OHS management systems	Fabrication, scrubber/stack and ventilation documentation
NFPA 68 (cross-reference)	Deflagration venting	Energetic-dust collector vent sizing (international reference)
NFPA 69 (cross-reference)	Explosion prevention (isolation, suppression, inerting)	Energetic-dust collector isolation (international reference)
AMCA 99 (cross-reference)	Spark-resistant fan construction (Type A/B/C)	Fan selection for classified and energetic areas

21. Offices, control buildings and amenities — Green Star, NABERS, NCC Section J and DDA AS 1428.1

Not every part of an explosives site is a process hazard. The administration buildings, control rooms, gatehouses, training facilities, crib rooms and amenities are conventional occupancies, and their HVAC is designed to ordinary commercial standards — but to a high one, because the major operators run corporate sustainability and accessibility commitments. The office and control-building HVAC meets NCC Section J energy efficiency, and many new and refurbished buildings target Green Star (the Green Building Council of Australia rating) and NABERS (the National Australian Built Environment Rating System) energy and indoor-environment ratings, which drive efficient air handling, heat recovery, demand-controlled ventilation to ASHRAE 62.1 / AS 1668.2, and good indoor-air-quality outcomes. Amenities and accessible facilities are designed to the Disability Discrimination Act framework and AS 1428.1 (design for access and mobility), which sets the requirements for accessible toilets, change facilities and circulation that the mechanical services have to support. This part of the site uses ordinary galvanised duct fabricated on the SBAL-V and SBFB-1500 to AS 4254 — the conventional HVAC product — and it is mentioned here because a fabricator serving an explosives operator supplies both the specialised process duct and the conventional building duct, and the two are designed and documented together.

22. Energy, heat recovery and decarbonisation — green ammonia and the future plant

Energy is a major operating cost in AN manufacturing, and the ventilation systems — large dust-collection fans, dilution ventilation, scrubber circuits — are significant energy consumers. Heat recovery is increasingly applied where it can be done without compromising the contamination-control and segregation rules: recovering heat from clean general-extract streams to temper make-up air, for example, is straightforward, while recovery from oxidiser-dust, acid-fume or energetic streams is constrained by the requirement that those streams never contaminate clean air and never accumulate residue in a recovery device. Demand-controlled ventilation — modulating airflow to the actual contaminant load rather than running flat out continuously — is applied in the occupied and general areas, with the process LEV held at its design rate because the contaminant control cannot be compromised.

The larger shift on the horizon is decarbonisation of the ammonia supply chain. Ammonia is conventionally made from hydrogen derived from natural gas; green ammonia — ammonia made from hydrogen produced by electrolysis using renewable electricity — is an active development area in Australia, with the country’s renewable resources and existing ammonia and AN infrastructure positioning it well. For the HVAC engineer, green-ammonia and renewable-hydrogen integration introduces hydrogen-handling areas with their own hazardous-area classification (hydrogen has a very wide flammable range and a very low ignition energy), and it reinforces the demand for energy-efficient ventilation across the whole site. The fundamentals of the AN, emulsion, ANFO and initiating-systems ventilation do not change — the oxidiser, corrosion, conductivity and dilution demands are the same — but the precursor end of the plant gains a hydrogen dimension, and the whole site faces tightening energy and emissions expectations that pull heat recovery and demand control further into the design.

23. Industry bodies, regulators and standards organisations

The Australian explosives sector is supported and overseen by an active set of bodies. The Australian Explosives Industry and Safety Group (AEISG) is the peak industry body for explosives manufacturers and users, producing widely used codes of practice covering AN storage and handling, emulsion, ANFO, and mobile processing units — documents that sit alongside the AS standards and that the ventilation and dust-control design has to respect. SAFEX International is the global association for the safe management of explosives, sharing safety learnings across the international industry. On the regulatory side, each state and territory has an explosives or dangerous-goods regulator administering the SSAN regime, the explosives licensing, and the dangerous-goods storage rules — the bodies that approve and inspect the magazines, the AN storage and the manufacturing licences. SafeWork Australia sets the model work-health-and-safety framework and the workplace exposure standards, with the state WHS regulators enforcing them. The state environment protection authorities license the scrubber and stack emissions. Standards Australia publishes the AS/NZS suite. Together these bodies form the framework that the HVAC design, the dust-control engineering and the commissioning documentation must satisfy, and a fabricator working in this sector benefits from understanding where each fits.

24. Competitive positioning — why specialised fabrication wins this market

The explosives and ammonium nitrate market is not a high-volume duct market, but it is a high-value, high-barrier one. A generic commercial fabricator who treats an AN plant or an emulsion facility as ordinary industrial work will get the material wrong (galvanised where stainless or FRP is required), get the construction wrong (sealed lock seams where continuous welds are required, fibrous lining where none is permitted), get the bonding wrong (no verified earth path on energetic-dust and detonator-area duct), and get the documentation wrong (no AS 4326, AS 2187.1, AS/NZS 60079 or dust-hazard-analysis trail). Each of those errors is a compliance failure that an explosives operator, its insurer and its regulator will not accept. The fabricators who win and keep this work are the ones who can produce, repeatably, a non-combustible, corrosion-resistant, conductive, hermetic, smooth, bonded, fully documented duct envelope — in galvanised, aluminised, 304/316L stainless and (in partnership) FRP — with the continuous-weld, spiral-forming and plasma-cutting capability that the specialised streams demand. That production capability is precisely what the SBKJ machine line delivers: the SBAL-V and SBAL-III auto duct lines, the SBSF-1525 and SB-ZF1500 continuous stitch welders, the SBFB-1500 spiral tubeformer, the SBPC1500 plasma cutter, the SBLR-600 lock former and the SBTF-1500/1602/2020 spiral-trunk family, supported by SBKJ’s Box Hill North VIC engineering team. The specialisation that locks out the generic competitor is the same specialisation that makes the market attractive: high value, long-term operator relationships, and repeat work across a small number of major, well-resourced, safety-driven customers.

25. Closing — SBKJ engineering support for Australian explosives and AN facilities

The Australian explosives and ammonium nitrate sector is a mature, safety-critical, heavily regulated industry, and it is also a growing one — driven by sustained mining demand across the Pilbara, the Bowen Basin and the Goldfields, by ongoing investment in AN and emulsion capacity, and by the coming decarbonisation of the ammonia supply chain. Every new plant, every expansion and every replacement of ageing ventilation infrastructure demands purpose-engineered ductwork that meets the full standards stack set out in this guide: AS 1668.2 dilution and make-up, AS 4254 construction, AS 4326 oxidiser handling, AS 2187.1 explosives storage, AS/NZS 60079 hazardous-area classification, AS 3780 and AS 1940 dangerous-goods handling, AS 3957 dust control, and the WES-driven sizing that ties it together — all delivered as a non-combustible, corrosion-resistant, conductive, bonded, documented envelope. The SBKJ Group engineering team in Box Hill North VIC is positioned to support Australian fabricators and the mechanical contractors who serve Orica, Dyno Nobel / Incitec Pivot, CSBP Wesfarmers, Maxam, AEL / AECI, Johnex, Downer Blasting Services, BME, Hanwha and Quantum Explosives, with machine supply, engineering documentation, commissioning support and ongoing technical advisory across every process zone described in this document.

We will be exhibiting at ARBS 2026 in Sydney in May with the full SBKJ machine portfolio plus reference samples relevant to explosives and AN duct fabrication — 304/316L stainless oxidiser-dust and acid-fume duct, hermetic continuous-weld seams, conductive bonded construction and spiral dust mains. Pre-show meetings with Australian explosives operators, dangerous-goods mechanical contractors and existing customers are scheduled across the week.