Refractory, Firebrick, Kiln Furniture, Ceramic Fibre & Monolithic Manufacturing HVAC Duct Guide

1. Why refractory and firebrick manufacturing HVAC is its own engineering discipline

Refractory manufacturing is one of the dustiest, hottest and most chemically varied heavy industries in Australia, and the HVAC ductwork inside a refractory plant carries a hazard load that has almost nothing in common with a commercial or light-industrial building. Within a single works — a firebrick plant, a monolithic and castable mixing facility, a kiln-furniture pressing shop or a refractory ceramic fibre line — you find respirable crystalline silica liberated by crushing fireclay and quartzite in one bay, alumino-silicate fibre being blown and cut at the next, coal-tar-pitch fume rising off a hot-press in the steel-ladle-brick area, graphite dust filling the carbon-refractory mill, and a tunnel kiln venting flue gas at well over 1500 °C at the back of the building. Each operation has its own dust chemistry, particle abrasiveness, fume toxicity, fibre carcinogenicity, combustion-product and combustible-dust profile, and each drives a different ventilation, extraction and duct-construction answer.

HVAC ductwork inside a refractory plant is not a commodity item. It is a process-engineering problem that sits at the intersection of respirable-crystalline-silica control (the single dominant health hazard, with a SafeWork Australia workplace exposure standard of just 0.05 mg/m3), refractory-ceramic-fibre carcinogen containment (RCF, IARC Group 2B, with a workplace exposure standard of 0.5 fibres per millilitre), high-temperature kiln-exhaust engineering (AS 1375 fuel-fired furnaces and kilns to 1800 °C), combustible carbon and graphite dust deflagration protection (AS/NZS 60079.10.2 with NFPA 68 and NFPA 69 cross-references), coal-tar-pitch-volatile PAH extraction (a confirmed carcinogen at a 0.2 mg/m3 limit), and hexavalent-chromium control on chrome-bearing products (Cr(VI) at the punishing 0.0003 mg/m3 limit). All of it sits inside the same building envelope, and all of it has to be documented against the Australian Standards and the model Work Health and Safety Regulations for the SafeWork Australia and state-EPA audit trail.

This guide writes against the breadth of the Australian refractory sector as it exists in 2026. The global refractory producers all run Australian operations: Vesuvius Australia supplies flow-control and monolithic refractories into steel and foundry; RHI Magnesita Australia covers basic brick, monolithics and flow control for steel, cement and non-ferrous; Calderys Australia (the former Imerys refractory monolithics business) supplies castables, gunning mixes and precast shapes; Morgan Advanced Materials runs its Thermal Ceramics Australia operation in insulating firebrick, refractory ceramic fibre and bio-soluble wool; and Unifrax/Alkegen supplies high-temperature insulation fibre and board. Australian-grounded businesses round out the sector: Refractory Solutions, Sandhurst Refractories, Email and Furnace Engineering, Steuler, Allied Mineral Products and the raw-material supplier Bisley & Company. Beyond the makers sit the refractory installers and contractors who line the kilns and vessels of BlueScope and Liberty steel, the cement kilns of Adelaide Brighton and Boral, and the alumina refineries and aluminium smelters of the resources sector — all of whom run their own brick-cutting, monolithic-mixing and gunning operations on site, with the same dust and HVAC demands as a dedicated refractory plant.

Geographically the sector clusters around the heavy-industrial corridors: Newcastle and Wollongong in NSW around the steel works; Melbourne and Dandenong in Victoria; Brisbane in Queensland; and Perth and Kwinana in Western Australia around alumina and mineral processing. The SBKJ Group engineering team operates from Box Hill North VIC and addresses Australian refractory manufacturers and their mechanical contractors directly — the businesses that have to design, fabricate, install and commission the dust-extraction, fume-capture, fibre-containment and kiln-exhaust ductwork that keeps a refractory plant inside its exposure standards and its EPA licence.

Across this entire sector, refractory ductwork must survive five simultaneous demands that explain why a generic commercial fabricator fails. Extreme abrasion resistance — refractory mineral dust (alumina, silica, magnesia, chromite, bauxite, zircon) is among the most abrasive dust any HVAC system handles, demanding heavy-gauge duct, wear-backed elbows and high transport velocity. Carcinogen-grade containment — RCS silica, RCF fibre, Cr(VI) and coal-tar-pitch PAH all carry exposure limits that leave no margin for leakage or under-capture. High-temperature service — kilns at 1500–1800 °C, driers and tempering ovens, demanding high-temperature stainless and engineered expansion joints. Combustible-dust explosion protection — carbon and graphite refractory dust triggering the full hazardous-area and deflagration-protection chain. And full regulatory documentation — every metre traceable to its standard, its zone, its exposure standard and its commissioning record. This guide walks every major process zone in turn, then closes with the SBKJ machine configuration that gives an Australian fabricator the production envelope to serve this market.

2. The Australian regulatory stack — AS 1668, AS 4254, AS 3957, AS 1375, AS/NZS 60079.10.2, AS 1530.4, AS/NZS 1715/1716, AS 2985/3640

Refractory HVAC in Australia sits on a stack of overlapping standards and regulations. The model Work Health and Safety Regulations make the workplace exposure standards legally enforceable, and SafeWork Australia plus the state regulators (WorkSafe Victoria, SafeWork NSW, Workplace Health and Safety Queensland, WorkSafe WA) audit against them. The standards split into mechanical-ventilation and dilution, duct construction, dust-hazard and dust-collection, kiln and furnace safety, combustible-dust hazardous-area classification, fire resistance, respiratory protection, exposure monitoring, and management systems.

2.1 AS 1668.1 and AS 1668.2 — mechanical ventilation and WES dilution

AS 1668.2 is the umbrella mechanical-ventilation standard for Australian buildings and the document that sets workplace-exposure-standard dilution requirements; AS 1668.1 covers fire and smoke control. A refractory plant falls under National Construction Code Class 8 industrial occupancy. In practice the building-volume minimum extract rate is irrelevant — localised exhaust ventilation at every crushing, grinding, screening, mixing, pressing, fibre-cutting and kiln point drives total exhaust far above the building figure. Where AS 1668.2 matters most is make-up air: every cubic metre extracted from a dust hood, fibre hood, bagging station or kiln-exhaust riser must be replaced by tempered, filtered, controlled-velocity supply air, keeping dusty production zones at neutral or slightly negative pressure relative to clean offices and laboratories so that dust, fibre and fume do not migrate, while still delivering enough heating in winter and relief in summer for a workforce in a building dominated by kiln heat gain.

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

AS 4254.1 (sheet metal) and AS 4254.2 (flexible) govern duct construction across the normal pressure ranges — low pressure (up to 500 Pa), medium pressure (up to 1000 Pa) and high pressure (up to 2500 Pa). Most refractory-plant supply, make-up and general extract sit inside AS 4254. The high-grain-loading abrasive dust mains run inside AS 4254 pressure ranges but at heavier gauge than the standard minimum specifies, because abrasion and rigidity, not pressure, set the wall thickness. Kiln, drier and tempering-oven exhaust in their hot stainless sections run beyond AS 4254 and require purpose-engineered construction; AS 4254 picks up again downstream of the dilution and cooling zone once gas temperature falls into range.

2.3 AS 3957 — dust hazard areas and central dust extraction

AS 3957 is the directly applicable standard for the dust-collection systems that dominate a refractory plant. It covers the design of localised exhaust ventilation and central dust extraction for hazardous dusts, and it is the document a refractory duct designer reaches for first. AS 3957 drives capture-hood face velocity, duct transport velocity (20–25 m/s for heavy abrasive refractory mineral dust to prevent dropout), branch and main sizing, and the central reverse-pulse baghouse configuration. For respirable crystalline silica, AS 3957 sits alongside the 0.05 mg/m3 workplace exposure standard and the model WHS silica provisions; for combustible carbon and graphite dust it sits alongside AS/NZS 60079.10.2 and the NFPA 68/69 deflagration-protection chain. The standard forces the designer to answer, at every collection point, what the dust is, how abrasive it is, whether it is combustible, what transport velocity holds it entrained, and what air-to-cloth ratio the baghouse needs.

2.4 AS 1375 — industrial fuel-fired appliances, furnaces and kilns

AS 1375 (the SAA industrial fuel-fired appliances code) governs the gas-fired tunnel, shuttle and periodic kilns, the drying ovens and the tempering ovens that are the thermal heart of a refractory plant. It sets burner-management, purge-cycle, flame-supervision, combustion-air and flue requirements for appliances burning natural gas, LPG or other fuels. For the HVAC designer, AS 1375 defines the kiln-exhaust topology: the flue and exhaust riser, the dilution-air provision to drop flue-gas temperature and dilute combustion products, the carbon-monoxide, oxides-of-nitrogen and sulfur-dioxide concentration limits in occupied areas, and the separation of high-temperature kiln exhaust from general facility extract. A refractory kiln firing to 1800 °C generates a flue-gas duty no commercial HVAC standard addresses; AS 1375 plus the high-temperature stainless and expansion-joint engineering covered later in this guide carries it.

2.5 AS/NZS 60079.10.2 — combustible-dust hazardous areas (carbon and graphite)

AS/NZS 60079.10.2 is the combustible-dust hazardous-area-classification standard, triggered in a refractory plant by carbon and graphite refractory dust (carbon-bonded magnesia-carbon brick, alumina-graphite shapes, graphite crucibles and electrodes). Fine carbon and graphite dust is combustible and can deflagrate, so the standard requires zoning — Zone 20 (continuous explosible-dust concentration) inside the duct interior and the collector, Zone 21 (occasional release in normal operation) around the open mill and transfer points, Zone 22 (unlikely, short duration) in the general area — and drives the selection of Ex-rated electrical equipment, conductive and bonded duct, and explosion-isolation devices. It works alongside the US references AS designers commonly cross-cite: NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems). Graphite dust is additionally electrically conductive and abrasive, which compounds both the explosion-protection and the duct-wear problem.

2.6 AS 1530.4 — fire resistance of building elements

AS 1530.4 covers fire-resistance testing of building elements including fire-rated duct penetrations through fire compartments. In a refractory plant this matters wherever a duct crosses between the kiln hall or dusty production zones and adjacent offices, laboratories, switchrooms or evacuation routes — the penetration must be rated (commonly 250 °C/2 hour duct fire integrity), with fire dampers to AS 1682 and the surrounding wall or floor assembly meeting the fire-resistance level called by the building’s National Construction Code approval. The high heat load of a kiln hall makes fire compartmentation and rated penetrations a more prominent design item than in a cool industrial building.

2.7 AS/NZS 1715 and AS/NZS 1716 — respiratory protective equipment

AS/NZS 1715 (selection, use and maintenance) and AS/NZS 1716 (equipment) govern the respiratory protective equipment that is the last line of defence for silica and RCF-exposed workers. Engineering controls — enclosure, localised exhaust, central extraction — come first, but a refractory plant cannot eliminate every exposure, so RPE is integral. For respirable crystalline silica and refractory ceramic fibre, powered air-purifying respirators (PAPR) with P2/P3 particulate filters are common, with fit-testing, maintenance and training documented under AS/NZS 1715. The HVAC design and the RPE programme are complementary: the better the localised exhaust captures at source, the lower the residual airborne concentration the RPE has to manage, and the air-monitoring data ties the two together.

2.8 AS 2985 and AS 3640 — exposure monitoring

AS 2985 (workplace atmospheres — respirable dust, gravimetric sampling) and AS 3640 (inhalable dust) define how breathing-zone air samples are taken and analysed to demonstrate compliance with the workplace exposure standards. For respirable crystalline silica the AS 2985 respirable sample is analysed (X-ray diffraction or infrared) to quantify the crystalline silica fraction against the 0.05 mg/m3 limit; for refractory ceramic fibre the membrane-filter phase-contrast microscopy method counts respirable fibres against the 0.5 fibres/mL limit. These monitoring standards close the loop on HVAC performance — a duct and baghouse system is only as good as the breathing-zone concentration it delivers, and the quarterly or task-based air-monitoring results are the proof. Health surveillance for silica-exposed workers is mandatory under the model WHS Regulations.

2.9 The wider stack — AS 4024, NCC Section J, ASHRAE 62.1, ISO management systems

Surrounding standards complete the picture. AS 4024 (safety of machinery) governs guarding on dust-collection and duct-access points. NCC Section J sets energy-efficiency requirements that bear on fan power, heat recovery and building-fabric performance — significant in an energy-intensive kiln plant. ASHRAE 62.1 is cross-referenced for outdoor-air ventilation rates in occupied office and control-room spaces. ISO 9001 (quality), ISO 14001 (environmental) and ISO 45001 (occupational health and safety) management systems frame the documentation, maintenance and continual-improvement obligations that wrap the whole HVAC installation. For combustible-dust systems, NFPA 68 and NFPA 69 provide the deflagration-venting and explosion-prevention engineering that AS/NZS 60079.10.2 zoning calls for.

3. Raw-material crushing, grinding and screening — respirable crystalline silica, the dominant hazard

The front end of every refractory plant is the raw-material department, and it is where the single most dangerous routine exposure in the industry lives. Refractory raw materials arrive as lump or aggregate — fireclay, calcined fireclay (chamotte), bauxite, calcined alumina, dead-burned magnesia, fused magnesia, chromite, zircon, quartzite, ganister, silica, andalusite, sillimanite, kyanite, graphite, silicon carbide — and are crushed in jaw and roll crushers, ground in ball, pan and pendulum mills, dried, screened across vibrating decks, classified, and stored in bins and silos before batching. Every one of these operations liberates dust, and a large fraction of that dust is respirable crystalline silica.

Respirable crystalline silica (RCS) is the hazard a refractory HVAC design must defeat first. Quartz, cristobalite and tridymite are the three crystalline polymorphs; fireclay, quartzite, ganister, silica brick raw materials and many alumino-silicate refractories are silica-rich. Particles below about 10 micron aerodynamic diameter are respirable — they penetrate to the gas-exchange region of the lung and cause silicosis (irreversible fibrotic lung scarring), lung cancer (RCS is an IARC Group 1 human carcinogen), and chronic obstructive pulmonary disease. The SafeWork Australia workplace exposure standard for respirable crystalline silica is 0.05 mg/m3 as an eight-hour time-weighted average, a figure that was halved in recent years and is enforced with mandatory air monitoring and health surveillance. Cristobalite — which forms when silica refractories are fired above roughly 1470 °C, and which becomes respirable again when fired silica brick is later cut, ground or demolished — is more toxic than quartz, and several jurisdictions apply an even tighter effective control expectation to it.

Defeating RCS at the source means total enclosure of every dust-generating point and localised exhaust ventilation that captures dust before it reaches the breathing zone. Jaw and roll crushers are hooded and enclosed; ball and pan mills are sealed and extracted; vibrating screens are fully enclosed in extracted cabinets; transfer points between conveyors are skirted, enclosed and extracted; silo and bin vents are filtered. The localised exhaust is designed to AS 1668.2 capture velocities — a capture velocity of 1.0–2.5 m/s at the point of dust release, rising for high-energy release such as crusher discharge — and ducted at 20–25 m/s transport velocity (refractory mineral dust is dense, so the transport velocity sits at the top of the range) to a central reverse-pulse fabric baghouse designed to AS 3957. The captured dust is heavy and abrasive, and the duct that carries it is the most demanding fabrication in the plant.

Duct construction for RCS mains is governed by abrasion and rigidity, not by pressure. Heavy-gauge galvanised or aluminised steel at 1.2–1.5 mm is standard, with abrasion-backed or replaceable-wear elbows at every change of direction (the outer radius of an elbow is where abrasive dust impinges and wears through first), long-radius bends rather than mitred where space allows, and minimal flat panels for dust to settle on — which is why spiral round duct is preferred over rectangular for the dust mains. The system is balanced so that every branch holds transport velocity simultaneously; a branch that drops below transport velocity accumulates a dense silica deposit that both reduces airflow and, in a carbon or graphite plant, becomes an ignition risk. Breathing-zone air sampling to AS 2985 quantifies the respirable crystalline silica fraction against the 0.05 mg/m3 limit, and that monitoring result is the ultimate measure of whether the enclosure and extraction design works.

4. Mixing, batching and binder addition — mineral dust plus binder fume

Downstream of the raw-material department, crushed and ground materials are weighed, batched and mixed with binders to form the body that will be pressed or cast. The mixing and batching hazard is twofold: continued mineral dust (including respirable crystalline silica) as dry powders are charged into mixers and bins, plus fume and vapour from the binders themselves. Refractory binders span a wide chemistry — calcium aluminate cement and hydratable alumina for castables, sodium silicate and colloidal silica, phosphate binders (mono-aluminium phosphate, phosphoric acid), sulfite lignosulfonate, resin (phenolic and furan) for resin-bonded products, and coal-tar pitch or tar for pitch-bonded steel refractories.

Dry-powder charging into mixers, weigh hoppers and intermediate bulk containers is a primary dust-release point and is hooded and extracted into the same RCS-controlled dust system as the raw-material department, sized for the dense mineral dust at 20–25 m/s transport velocity. The binder fume hazard depends on chemistry. Phosphate binders release acidic mist and, when heated, phosphorus oxides; phenolic and furan resins release formaldehyde and furfuryl alcohol vapour during mixing and far more during subsequent drying and curing; pitch and tar release coal-tar-pitch volatiles (covered in detail in the pitch-bonded section). These fume streams require dedicated localised exhaust at the mixer, separate from the dry-dust system where the chemistry is corrosive or condensable, and routed in 316L stainless to a scrubber, thermal oxidiser or filter appropriate to the contaminant. Where the binder is purely aqueous (cement, colloidal silica) the mixing fume is benign moisture and the dust system carries the load. The HVAC designer maps each mixer to its binder chemistry and provides the matching capture and treatment, never assuming a single generic mixing exhaust will serve every product line.

Capture velocity at a mixer charge point follows AS 1668.2 — typically 1.0–1.5 m/s at the opening, with a canopy or enclosing hood sized to the release geometry. The make-up air balance matters here because aggressive extraction at multiple mixers can pull the mixing hall negative enough to draw uncomfortable draughts and disturb weigh-scale accuracy; AS 1668.2 make-up air sizing keeps the room balanced.

5. Pressing and forming — dry-press brick and isostatic pressing dust

Formed refractory shapes are produced by several routes, and each releases dust. Dry-press (mechanical and hydraulic) brick presses compact a semi-dry granular body in steel moulds at high tonnage; cold isostatic pressing (CIP) compacts powder in flexible moulds under hydrostatic pressure for high-performance and complex shapes; extrusion forms plastic-consistency bodies; and slip-casting and vibration-casting form monolithic and precast shapes. Dry-pressing and isostatic pressing of granular and powder bodies are dust-release operations — the press cavity is charged with a dusty granular feed, the press stroke ejects fine dust, and mould cleaning and demoulding release more.

The dust here carries the same respirable-crystalline-silica hazard as the raw-material and mixing departments wherever the body is silica-bearing, and the same control philosophy applies: enclose the press charge and demould zone, capture at source with localised exhaust to AS 1668.2 capture velocity, and duct the dense dust at 20–25 m/s to the central baghouse. Press areas are mechanically busy — moulds change, operators load and unload — so capture hoods must be designed not to obstruct operation while still capturing the dust plume from the press stroke. For isostatic pressing the pressure-vessel and fluid systems add their own engineering, but the airborne-dust HVAC demand is the granular-feed charging and the demould dust, both controlled by enclosure and localised exhaust.

For carbon-bonded and graphite-bearing bodies the pressing dust is combustible, and the press dust-extraction branch carries the AS/NZS 60079.10.2 combustible-dust zoning, conductive and bonded duct, and explosion-isolation requirements covered in the graphite section. For chrome-bearing bodies the press dust carries the Cr(VI) hazard and a dedicated non-recirculated extraction. The press department therefore connects to whichever of the plant’s dust systems matches the product chemistry — general RCS dust, combustible-dust, or Cr(VI) — and the HVAC designer routes each press to the correct collector.

6. Drying ovens — moisture removal and binder off-gas

Pressed, cast and extruded refractory shapes contain water (from aqueous binders and forming) and, where resin or pitch binders are used, organic volatiles, and they must be dried before firing to avoid steam-explosion spalling in the kiln. Drying ovens (tunnel dryers, chamber dryers, humidity-controlled dryers) run at moderate temperature — typically 80–200 °C — and their exhaust carries water vapour plus, depending on the binder, formaldehyde and furfuryl alcohol from phenolic and furan resins, ammonia from some binders, and the early fraction of coal-tar-pitch volatiles from pitch-bonded shapes warming up.

The drying-oven exhaust HVAC demand is dominated by the binder off-gas where present. A purely aqueous body dries to benign humid air that is exhausted through a moisture-tolerant duct (stainless or coated steel to resist condensate corrosion) with the latent load managed in the make-up air system. A resin-bonded body dries with formaldehyde and furfuryl alcohol off-gas that must be captured and treated — the dryer exhaust is ducted in 316L stainless to a thermal oxidiser or scrubber, sized to keep the formaldehyde concentration in any occupied area below its workplace exposure standard, and the dryer is run under negative pressure so off-gas does not escape into the building. Pitch-bonded shapes warming in the dryer release the early, most volatile fraction of the coal-tar-pitch volatiles and are handled on the dedicated pitch-fume system. Drying ovens fall under AS 1375 where fuel-fired, with the burner-management, purge and flame-supervision requirements that implies, and their condensate-prone exhaust is constructed to resist the acidic condensate that forms when moist binder-laden gas cools in the duct.

7. Firing kilns — tunnel, shuttle and periodic kilns to 1800 °C, the high-temperature exhaust problem

The firing kiln is the thermal heart of a refractory plant and the source of the highest-temperature exhaust in the building. Dried refractory shapes are fired to develop their ceramic bond, density and high-temperature properties. Tunnel kilns move ware continuously on kiln cars through preheat, firing and cooling zones; shuttle (intermittent) kilns and periodic kilns fire a batch and then cool. Peak firing temperature depends on the product: fireclay and chamotte brick around 1300–1400 °C, high-alumina brick 1500–1600 °C, silica brick 1450–1500 °C, and basic (magnesia, magnesia-chrome, dolomite) brick up to 1700–1800 °C. Most Australian refractory kilns are natural-gas fired and designed, built and operated to AS 1375 with full burner-management systems, purge cycles before light-up, and flame supervision.

The kiln flue gas is a hot, chemically active stream. It carries the products of combustion (carbon dioxide, carbon monoxide where combustion is incomplete, water vapour), oxides of nitrogen (NOx) formed at the high flame temperature, and sulfur dioxide (SO2) liberated from sulfur-bearing raw materials and from pitch and tar in pitch-bonded ware. Fluorine and chlorine compounds appear with some raw materials. The HVAC engineering of the kiln exhaust is dominated by temperature and by these combustion products. The exhaust riser directly off the kiln cannot be galvanised duct — galvanising volatilises and the steel loses strength well below kiln-flue temperature. The first section of the riser is high-temperature austenitic stainless (309 or 310S, good to roughly 1000–1100 °C continuous), refractory-lined steel, or in the most severe duty a nickel-alloy section, with engineered bellows expansion joints to absorb the very large thermal growth. Downstream, dilution air is introduced (under AS 1375 and AS 1668.2) to drop the gas temperature and dilute the combustion products, and once the gas is cool enough the duct transitions to 316L or coated steel in the AS 4254 range.

Dilution and dispersion are calculated against the occupied-area limits: carbon monoxide below the 30 ppm workplace exposure standard, nitrogen dioxide below the 3 ppm eight-hour limit (with a 5 ppm short-term peak limit), sulfur dioxide below the 2 ppm limit, and carbon dioxide below 5000 ppm. The kiln-exhaust stack is sized and located for atmospheric dispersion to satisfy the state EPA licence, and stack emission monitoring (for NOx, SO2, CO and particulate) is commonly a licence condition. Thermal growth governs the mechanical design: a 30 m run of 309/310S stainless heated from ambient to 1000 °C grows on the order of 300 mm, so bellows expansion joints, sliding guides and anchor points are engineered before any duct is fabricated, and the supports carry the hot weight without restraining the growth. Kiln heat recovery (covered later) takes useful heat out of this stream before it reaches the stack, dropping both the stack temperature and the building’s energy bill.

8. Refractory ceramic fibre (RCF) manufacturing and cutting — the carcinogen-grade containment problem

Refractory ceramic fibre — alumino-silicate wool, also marketed as RCF or by various trade names — is a synthetic vitreous fibre and the most tightly controlled airborne hazard in a refractory plant. It is manufactured by melting alumina and silica (and minor additives) at around 1800 °C and blowing or spinning the molten stream into fine fibres, which are collected into bulk wool and converted to blanket, board, paper, module, felt, vacuum-formed shapes and bulk fibre for high-temperature insulation. Morgan Advanced Materials (Thermal Ceramics Australia) and Unifrax/Alkegen are the principal RCF and high-temperature fibre suppliers into the Australian market, alongside bio-soluble alkaline-earth-silicate (AES) wool that is progressively substituting for RCF where service temperature allows.

The hazard is the fibre itself. Respirable RCF fibres — defined as length greater than 5 micron, diameter less than 3 micron, and aspect ratio greater than 3:1 — are biopersistent in lung tissue and are classified by IARC as Group 2B (possibly carcinogenic to humans). RCF carries one of the very lowest fibre exposure standards in the SafeWork Australia Hazardous Substances Information System: a workplace exposure standard of 0.5 fibres per millilitre of air as an eight-hour time-weighted average, measured by the membrane-filter phase-contrast microscopy method (the same method used for asbestos fibre counting). Fibre is released wherever RCF is handled mechanically — the fibre-forming and collection line itself, and downstream cutting, needling, die-cutting, slitting, vacuum-forming, machining of board and shapes, and packing. A further hazard appears after service: when RCF is heated above about 900–1000 °C in use it partially devitrifies to cristobalite, so high-temperature-exposed and end-of-life RCF carries a respirable-crystalline-silica hazard layered on top of the fibre hazard.

Containing RCF demands dedicated localised exhaust ventilation with full containment, engineered to a higher integrity than the general dust system. The fibre-forming line is enclosed and extracted. Every downstream fibre-generating operation — cutting tables, die-cutters, needling lines, packing stations — is fitted with low-velocity, high-volume capture hoods positioned to draw fibre away from the operator’s breathing zone (RCF fibre is light and is captured by volume flow rather than the high transport velocity used for dense mineral dust; the duct transport velocity is moderated to avoid abrading fibre into finer respirable fragments while still preventing settlement). The RCF extract duct is dedicated 316L stainless, never shared with the general dust system, continuously welded for a hermetic envelope, and routed to a dedicated baghouse with HEPA polishing filtration to capture the finest respirable fibre before discharge. Operators wear powered air-purifying respirators selected to AS/NZS 1715/1716, fibre is bagged and handled wet or damp where practicable to suppress airborne release, and breathing-zone fibre counts against the 0.5 fibres/mL limit are taken regularly. The HVAC fabricator’s role is to deliver duct that is leak-free, smooth-bored, easy to clean and unambiguously segregated from every other stream in the plant.

9. Monolithic, castable and gunning-mix bagging — dust at the pack-out

A large and growing share of the refractory market is monolithic — castables, gunning mixes, ramming mixes, plastics, mortars and dry-vibration mixes supplied as dry powder in bags, bulk bags and silos for the customer to mix and install on site. Calderys Australia, Vesuvius Australia, RHI Magnesita Australia and Allied Mineral Products all run monolithic production, and the monolithic plant is a powder-handling and bagging operation as much as a refractory plant. The dominant HVAC hazard at the pack-out end is dust — fine mineral powder (calcined alumina, fused and sintered aggregates, calcium aluminate cement, microsilica, reactive alumina, additives) released during blending, conveying, weighing and bagging.

Microsilica (silica fume) deserves particular note: it is an ultrafine amorphous silica additive used in low-cement and ultra-low-cement castables, and while amorphous silica is far less hazardous than crystalline silica, its extreme fineness makes it a significant nuisance-dust and respirable-fraction control problem, and the dust system must capture it efficiently. Crystalline-silica-bearing aggregates in the mix carry the RCS hazard at the 0.05 mg/m3 limit as everywhere else in the plant.

Bagging-station HVAC is a well-understood problem: enclosed or hooded bag-filling spouts with integral extraction, bag-flattening and de-dusting before palletising, bulk-bag (FIBC) filling under extracted hoods, and silo-loading vents filtered to atmosphere. The extraction is ducted at 20–25 m/s (the powders are dense) to the central or a dedicated baghouse, and the captured fines are returned to process or disposed of as appropriate. Capture velocity at the bag spout follows AS 1668.2; the make-up air keeps the bagging hall balanced. Where the monolithic contains carbon, graphite or chrome the bagging dust carries the corresponding combustible-dust or Cr(VI) requirement and is routed accordingly.

10. Pitch-bonded and tar-bonded refractory — coal-tar-pitch volatiles and PAH

Pitch-bonded and tar-bonded refractories — magnesia-carbon, dolomite and alumina bricks bonded with coal-tar pitch or tar — are workhorse linings for steelmaking ladles, torpedo cars, basic-oxygen and electric-arc furnace vessels, and their manufacture carries one of the most serious carcinogen hazards in the industry. The pitch or tar binder is mixed (often hot) with the aggregate, the body is hot-pressed, and the pressed brick is tempered and sometimes coked. At every hot step the binder releases coal-tar-pitch volatiles (CTPV) — a complex mixture of polycyclic aromatic hydrocarbons (PAH) including benzo(a)pyrene and many other ring compounds, several of which are confirmed human carcinogens, and which appear as a characteristic blue fume.

The SafeWork Australia workplace exposure standard for coal-tar-pitch volatiles is 0.2 mg/m3 (benzene-soluble fraction) as an eight-hour time-weighted average, and PAH are dermal as well as respiratory carcinogens, so skin protection accompanies the respiratory and HVAC controls. The HVAC envelope for pitch-bonded production resembles a coke-oven, carbon-anode or carbon-bake plant far more than a ceramic kiln. Hot mixing, hot pressing and tempering stations are enclosed and fitted with dedicated high-temperature localised exhaust that captures the blue PAH fume at source. The captured fume is hot and laden with condensable tar — as it cools in the duct the PAH condense to a sticky, flammable tar film on the duct walls — so the extract duct is 316L stainless, insulated or heat-traced to keep the gas above the condensation point as far as practicable, sized to keep transport velocity high enough to carry condensate forward, and fitted with bolted access doors at every elbow and junction for routine cleanout. Before discharge the stream passes through a tar-knockout stage — commonly a wet electrostatic precipitator or a thermal oxidiser — to capture or destroy the PAH and satisfy the EPA licence and the 0.2 mg/m3 exposure standard. Operators wear organic-vapour and particulate respiratory protection to AS/NZS 1715/1716. The condensable, flammable, carcinogenic nature of the fume makes this the most demanding fume-extraction fabrication in a refractory plant.

11. Graphite and carbon refractory — combustible-dust explosion protection

Carbon and graphite refractories — carbon-bonded magnesia-carbon and alumina-magnesia-carbon brick, alumina-graphite continuous-casting shapes (submerged entry nozzles, ladle shrouds, stopper rods), graphite crucibles, and carbon and graphite electrode and block products — introduce a combustible-dust explosion hazard that no other refractory chemistry presents. Crushing, milling, mixing, pressing, machining and finishing graphite and carbon liberate fine carbon dust, and fine carbon and graphite dust suspended in air at sufficient concentration with an ignition source can deflagrate.

This triggers AS/NZS 60079.10.2 combustible-dust hazardous-area classification: Zone 20 (continuous explosible-dust concentration) inside the duct interior and the dust collector, Zone 21 (occasional release in normal operation) around the open mill, mixer and transfer points, and Zone 22 (unlikely, short duration) in the general area. The workplace exposure standard for graphite (respirable) is 3 mg/m3 as an eight-hour time-weighted average, so there is a health-dust control demand alongside the explosion-protection demand. The dust-extraction system for carbon and graphite refractory must therefore satisfy both. Duct is conductive throughout (316L stainless), continuously bonded with conductive flange gaskets at every joint and externally bonded with copper or stainless strap to the building earth grid (resistance below 1 ohm to ground at every section, verified at commissioning), because graphite dust is electrically conductive and static discharge is a credible ignition source. Explosion-isolation devices — chemical-suppression, flap-valve or rotary-valve isolation per NFPA 69 — are installed between the duct main and the collector to stop a deflagration in the collector propagating back into the duct, and the collector itself carries NFPA 68 deflagration-venting. Where machining of fired carbon or graphite generates credible sparks, spark-detection and abort-gate systems are fitted on the duct run. Graphite dust is also abrasive, so the duct-wear engineering of the dense-dust section applies on top of the explosion protection. This double demand — explosion-protected and abrasion-resistant — is why the carbon-refractory dust main is the most heavily engineered duct in the plant after the kiln exhaust.

12. Chrome-bearing refractory — hexavalent chromium control

Chrome-bearing refractories — magnesia-chrome (mag-chrome) and chrome-alumina brick and shapes used in cement rotary-kiln burning zones, glass-tank regenerators, non-ferrous (copper, lead, nickel) smelting furnaces and some steel applications — are manufactured from chromite ore (iron-chromium spinel, FeCr2O4). The chromium in raw chromite is trivalent and relatively low-hazard, but firing magnesia-chrome brick at high temperature in the presence of alkalis and oxygen oxidises a fraction of the chromium to the hexavalent state, and hexavalent chromium, Cr(VI), is a confirmed human lung carcinogen.

Cr(VI) is then present in kiln dust from firing mag-chrome ware, in the machining dust from grinding fired mag-chrome brick, and in spent-lining demolition dust. The SafeWork Australia workplace exposure standard for hexavalent chromium is 0.0003 mg/m3 as an eight-hour time-weighted average, expressed as chromium — one of the very lowest limits in the entire standard, three orders of magnitude below the respirable-crystalline-silica limit and demanding correspondingly higher control integrity. Controlling Cr(VI) means total enclosure of every chrome-refractory crushing, mixing, pressing, firing-dust and machining operation; dedicated localised exhaust and a dedicated baghouse that is never recirculated and never cross-connected to other product streams (to avoid contaminating otherwise lower-hazard dust with Cr(VI)); continuous or frequent breathing-zone monitoring against the 0.0003 mg/m3 limit; and powered air-purifying respirators with appropriate filters. Many Australian refractory makers have reduced or eliminated chrome-bearing products specifically because of the Cr(VI) compliance and waste-disposal burden (spent chrome refractory is a regulated waste), but mag-chrome remains in production for specific high-duty applications where no chrome-free substitute matches its performance, and where it is made the HVAC must hold to the 0.0003 mg/m3 standard.

13. Kiln-furniture and fired-brick machining — silica dust at the finishing end

Kiln furniture — the setters, batts, posts, props, saggars, beams and rollers that support and separate ware during firing in the kilns of other ceramic and refractory makers — and finished refractory shapes are frequently machined after firing to final dimension and surface. Fired refractory is hard, dense and abrasive, and dry cutting, grinding, drilling and surface-grinding of fired brick, shapes and kiln furniture liberates fine dust — and where the body is silica-bearing or has formed cristobalite during firing, that dust is respirable crystalline silica.

Machining fired silica brick is a particularly hazardous RCS operation because firing above 1470 °C converts much of the quartz to cristobalite, the more toxic polymorph, so the machining dust from fired silica refractory carries a cristobalite hazard. The control is the same in principle as the raw-material department but applied at the machine: each cutting, grinding and drilling station is enclosed or hooded with localised exhaust to AS 1668.2 capture velocity, wet methods (water-fed saws and grinders) are used where the product and process allow because water suppression dramatically cuts airborne dust, and the captured dry dust is ducted at 20–25 m/s to the dust collector. Where the machined product is carbon or graphite the dust is combustible and the machining-dust branch carries the AS/NZS 60079.10.2 zoning, conductive bonded duct and spark-detection/abort-gate provisions; where it is chrome-bearing the branch carries the Cr(VI) dedicated extraction. Fired-brick machining is the finishing end of the plant, but it regenerates the same respirable-crystalline-silica hazard that the raw-material department creates, and it is controlled with the same enclosure-and-extraction discipline.

14. Central dust collection — baghouse design for abrasive refractory mineral dust

The heart of a refractory plant’s dust control is the central dust collector, and for the heavy, abrasive, high-grain-loading mineral dust of a refractory works it is almost always a reverse-pulse (pulse-jet) fabric baghouse designed conservatively to AS 3957. The baghouse pulls dust-laden air from the network of capture hoods through the duct mains, filters it through fabric bags or cartridges, pulse-cleans the collected dust off the media into a hopper, and discharges cleaned air to atmosphere or back to the building.

The critical design parameter is the air-to-cloth ratio (filtration velocity) — the volume of air filtered per unit area of filter cloth. For heavy abrasive mineral dust (silica, alumina, chromite, magnesia) the air-to-cloth ratio runs low, typically 0.9–1.2 m3/min per m2 of cloth (roughly 3–4 ft/min) for a pulse-jet unit, to keep the upward can velocity low, reduce abrasive wear on the bags and hold particulate emission below the state EPA limit. A baghouse run at too high an air-to-cloth ratio blinds, wears its bags rapidly, and emits. Bag media is selected for temperature and dust: polyester for ambient mineral dust, aramid (Nomex-type) for warmer streams, and PTFE-membrane-laminated media for the finest respirable silica fraction and for the highest emission-control duty. The collector inlet is fitted with baffle plates and abrasion-resistant inlet liners to protect the tube sheet and hopper from the incoming abrasive stream, and the hopper is steeply sloped with appropriate discharge (rotary valve or screw) to avoid dust bridging.

For combustible carbon and graphite dust the baghouse additionally carries NFPA 68 deflagration-vent panels (sized to the dust deflagration index Kst and relieving to a safe location), NFPA 69 explosion-prevention measures, and full bonding and earthing of the collector and its hopper. The duct feeding the collector must hold transport velocity (20–25 m/s for dense refractory dust) right up to the inlet so that dust does not settle and accumulate in the main — a settled accumulation both starves the system of airflow and, in a combustible-dust plant, becomes a deflagration fuel bed and ignition risk. Filter selection, air-to-cloth ratio, inlet protection and explosion protection together define a baghouse that survives years of abrasive refractory duty while holding emission and exposure inside the licence and the workplace exposure standards.

15. RCS and RCF control and monitoring — closing the loop on the two carcinogens

Respirable crystalline silica and refractory ceramic fibre are the two carcinogen-grade airborne hazards that define a refractory plant’s HVAC, and both demand a control-and-monitoring loop, not just an extraction system. Control follows the hierarchy: elimination and substitution first (substituting low-silica raw materials, AES bio-soluble wool for RCF, chrome-free for chrome refractory where performance allows), then engineering controls (enclosure, localised exhaust, central extraction, wet methods), then administrative controls (work systems, rotation, restricted zones), then respiratory protective equipment as the last line. The HVAC system is the dominant engineering control, and its performance is measured by breathing-zone air monitoring.

For respirable crystalline silica, breathing-zone samples are taken to AS 2985 (gravimetric respirable sampling using a cyclone size-selector) and the respirable dust is analysed by X-ray diffraction or infrared spectroscopy to quantify the crystalline silica fraction (quartz, cristobalite, tridymite) against the 0.05 mg/m3 eight-hour-time-weighted-average limit. For refractory ceramic fibre, breathing-zone samples are taken on a membrane filter and counted by phase-contrast optical microscopy (the membrane-filter method) for respirable fibres against the 0.5 fibres/mL limit. Monitoring is task-based and periodic, the frequency set by the risk and the regulator, and the results drive both verification (is the HVAC holding the exposure below the limit?) and continuous improvement (which task or hood needs better capture?). Health surveillance — respiratory questionnaires, lung-function testing and, for silica, low-dose chest imaging — is mandatory for silica-exposed workers under the model WHS Regulations, and the air-monitoring data plus the health-surveillance data plus the HVAC maintenance records together form the compliance package a refractory manufacturer presents to SafeWork and the EPA. The HVAC fabricator’s contribution is a duct and capture system that is leak-free, balanced, easy to maintain and documented — because a system that cannot hold transport velocity, or that leaks fibre and dust at the flanges, fails the air-monitoring test no matter how the rest of the plant is run.

16. WES dilution and capture-velocity calculation — sizing the extraction

The quantitative core of refractory HVAC design is two calculations: the capture-velocity-and-flow calculation that sizes each localised-exhaust hood, and the dilution calculation that sizes the general ventilation against the workplace exposure standards. Both follow AS 1668.2.

Capture velocity is the air velocity at the point of contaminant release needed to draw the contaminant into the hood against room air currents. AS 1668.2 and accepted industrial-ventilation practice set capture velocity by release energy: roughly 0.25–0.5 m/s for release into still air with low energy (a quiet evaporating surface), 0.5–1.0 m/s for release into moderately still air at low velocity (mixing, bagging at low energy), 1.0–2.5 m/s for active generation into rapid air motion (crushing, screening, conveyor transfer, press ejection), and 2.5–10 m/s for high-energy release into very turbulent air (high-energy grinding, abrasive blasting). The hood exhaust flow is then the capture velocity multiplied by the area through which air must be drawn at the contaminant’s location, with hood-entry-loss and capture-distance factors applied — a hood loses capture rapidly with distance, so hoods are placed as close to the release as operation allows. For dense refractory dust the captured air is then carried at 20–25 m/s duct transport velocity to keep the dust entrained.

The dilution calculation, where general dilution rather than local capture is the control (for a low-toxicity contaminant or as a backup), sizes the ventilation rate to keep the room concentration below the workplace exposure standard. The steady-state dilution flow is the contaminant generation rate divided by the allowable concentration (the workplace exposure standard, with a safety factor applied for incomplete mixing). For the carcinogen-grade contaminants — RCS at 0.05 mg/m3, RCF at 0.5 fibres/mL, Cr(VI) at 0.0003 mg/m3, CTPV at 0.2 mg/m3 — dilution is never the primary control; the limits are far too low for general dilution to be economic or reliable, so local capture at source is mandatory and dilution is only a secondary safeguard. For the kiln combustion products dilution does feature: the dilution-air flow into the kiln exhaust is sized to bring carbon monoxide below 30 ppm, nitrogen dioxide below 3 ppm (5 ppm peak), sulfur dioxide below 2 ppm and carbon dioxide below 5000 ppm in any occupied area, and to drop the gas temperature into the range the downstream duct material can take. Every hood flow and every dilution flow sums into the total plant exhaust, and the make-up air system is sized to match so the building pressure balance holds.

17. Duct material, gauge and construction selection for refractory service

Material and gauge selection in a refractory plant is driven by four factors in combination: abrasion, temperature, chemistry and combustibility. The selection logic runs as follows. For abrasive mineral dust mains (silica, alumina, magnesia, chromite, bauxite, zircon) carrying dense dust at 20–25 m/s, the duty is abrasion and rigidity: heavy-gauge galvanised or aluminised steel at 1.2–1.5 mm, spiral round for strength and to avoid flat settling surfaces, with abrasion-backed or replaceable-wear elbows. For carcinogen-grade and corrosive-condensate streams (RCF fibre, Cr(VI), pitch PAH, acidic binder fume), the duty is containment and corrosion resistance: 316L stainless at 1.0–1.5 mm, continuously welded for a hermetic envelope. For the hot section directly off a kiln, drier or tempering oven above about 800 °C, the duty is high-temperature strength and oxidation resistance: 309 or 310S high-temperature austenitic stainless, or a nickel alloy for the most severe duty, in the first several metres of riser, transitioning to 316L or coated steel once dilution and cooling drop the gas temperature. For combustible carbon and graphite dust the duty adds conductivity and bonding: 316L stainless, continuously welded, fully bonded and earthed.

Construction follows the material and duty. Lighter supply, make-up and general extract duct is lock-seamed (Pittsburgh or snap-lock) and sealed to AS 4254. Dust mains, fume mains and combustible-dust mains are welded — a continuous TIG longitudinal weld on the seam — because a welded seam is hermetic (no fibre or fume leakage), conductive and bonded (for combustible dust), and far stronger against abrasion and internal pressure than a sealed lock. Flanges are TDF or equivalent for the lighter duct and welded flanges for the welded duct, with conductive ATEX-rated gaskets where bonding is required. Expansion joints (stainless bellows) are engineered into the hot kiln-exhaust runs to absorb thermal growth. Access and cleanout doors are provided at elbows and intervals along dust and condensable-fume mains. Every construction choice is documented against AS 4254 (where applicable), the relevant exposure standard, and the hazardous-area zone, so the commissioning and audit trail is complete.

18. SBKJ machine line for refractory HVAC duct fabrication

For an Australian fabricator or mechanical contractor serving the refractory sector from Box Hill North VIC, the SBKJ Product Catalog 2026 machine line provides the production envelope to fabricate every duct type a refractory plant needs — from the heavy-gauge abrasion-resistant dust main to the high-temperature kiln-exhaust riser to the hermetically welded RCF and pitch-fume containment duct. The roles map as follows.

• SBAL-V auto duct line — the workhorse for supply-air, make-up-air and general extract duct, and for the 316L stainless containment duct (RCF, Cr(VI), pitch fume) with the stainless option engaged. Production envelope 0.7–1.6 mm in galvanised, aluminised and 304/316L stainless, with TDF flange forming in-line. The make-up-air system that balances a refractory plant’s heavy extraction is largely SBAL-V work.
• SBAL-III heavy-gauge auto duct line — the heavy-gauge 1.6–2.0 mm line for the abrasion-resistant mineral-dust mains and the general high-temperature kiln-exhaust mains downstream of the dilution and cooling zone. Where wall thickness is set by abrasion and rigidity rather than pressure, the SBAL-III carries it.
• SBSF-1525 longitudinal stitch welder — the continuous-TIG longitudinal seam welder for the hermetic envelopes: RCF carcinogen-fibre containment, pitch-PAH fume extract, Cr(VI) dedicated extraction, combustible carbon/graphite dust mains, and the 250 °C/2 hour fire-rated risers to AS 1530.4. Where the duct must not leak fibre or fume and must be conductive and bonded, the SBSF-1525 makes the seam.
• SB-ZF1500 longitudinal stitch welder — the in-line continuous longitudinal welder running with the SBFB-1500 on spiral mains 1000–1500 mm, depositing the continuous TIG bead that turns a spiral mechanical lock into a hermetic, bonded, combustible-dust-rated and condensate-prone-fume-rated main.
• SBFB-1500 spiral tubeformer — the single most-used machine for refractory duct, producing spiral round duct 80–1500 mm diameter in galvanised, aluminised and stainless at 0.6–1.5 mm. Spiral round is the correct geometry for abrasive dense dust (no flat settling panels, strong lock) and for combustible dust (weldable to a bonded hermetic envelope). The dust mains, RCF mains and machining-dust mains are largely SBFB-1500 work.
• SBPC1500 plasma cutter — the plasma cutter for custom high-temperature transitions, tapered cones, mitred elbows, refractory-anchor stud plates and bellows expansion-joint flanges in 309/310S high-temperature stainless and Inconel 625 up to 25 mm thickness. The kiln-exhaust hot-side fabrication and the pitch hot-press hood transitions are SBPC1500 work.
• SBLR-600 lock former — the rollformer producing the Pittsburgh lock and snap-lock longitudinal seams for rectangular supply, return and lighter extract duct, with heavy-gauge tooling for 1.2 mm-plus stainless containment duct.
• SBTF-1500/1602/2020 spiral former — the spiral trunk-main family for the large mains 1500–2000 mm diameter into a centralised baghouse, and for cleanroom and large supply trunk mains where the plant runs a controlled-environment area.

Every spec referenced here for an actual customer quote must be confirmed against the SBKJ Product Catalog 2026 verbatim — the machine names, gauge ranges and roles above describe the fabrication envelope, and the catalog is the source of truth for any quoted figure. The combined machine fit delivers the production capacity to cover every duct requirement across the Australian refractory sector, from the firebrick and kiln-furniture plants of Newcastle and Wollongong NSW and Melbourne and Dandenong VIC, to the monolithic and castable plants of Brisbane QLD, to the refractory operations around the alumina and aluminium industry of Perth and Kwinana WA.

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

A refractory HVAC installation is only complete when it is commissioned, measured and verified against design and against the regulatory targets. Commissioning a refractory dust, fume, fibre and kiln-exhaust system runs through a defined sequence. Pre-commissioning checks confirm duct construction to AS 4254, weld integrity on the welded mains, expansion-joint installation on the hot runs, and earth-bonding continuity on every combustible-dust section (resistance below 1 ohm to ground at every flange and isolation device, verified with a hand-held meter). Pressure testing to 1.5 times design pressure for 30 minutes on every branch confirms the duct will hold without leakage. Airflow commissioning balances every hood and branch to its design flow and confirms transport velocity (20–25 m/s) is held in every dust main simultaneously — a system that meets total flow but leaves one branch below transport velocity will accumulate dust and fail in service. Baghouse commissioning sets the pulse-cleaning sequence, confirms the air-to-cloth ratio, and checks emission at the stack.

Measurement and verification then proves the system delivers its purpose: breathing-zone air monitoring to AS 2985 for respirable crystalline silica against 0.05 mg/m3, membrane-filter fibre counting for RCF against 0.5 fibres/mL, Cr(VI) sampling against 0.0003 mg/m3 where chrome refractory is made, CTPV sampling against 0.2 mg/m3 on pitch-bonded lines, and combustion-product measurement (CO below 30 ppm, NO2 below 3 ppm, SO2 below 2 ppm, CO2 below 5000 ppm) in occupied areas near the kiln. Stack emission testing satisfies the EPA licence. The commissioning deliverable is a NATA-certified report that ties every duct branch back to its AS/NZS 60079.10.2 hazardous-area zone (where combustible), its AS 3957 dust hazard analysis, its AS 1375 kiln-exhaust classification, its target workplace exposure standard, and its as-built construction and test records. That report becomes the foundation document for the manufacturer’s ongoing SafeWork and EPA compliance, and for the periodic re-verification (typically annual or more frequent for the carcinogen-grade streams) that confirms the system continues to perform as the plant ages and the product mix changes.

20. Standards and exposure-limit reference table

The following consolidates the standards and workplace exposure standards that govern refractory-manufacturing HVAC in Australia. It is a reference summary; the current published Australian Standards and the current SafeWork Australia workplace exposure standards always take precedence for design and compliance.

• AS 1668.1 — fire and smoke control in buildings (mechanical).
• AS 1668.2 — mechanical ventilation in buildings, workplace-exposure-standard dilution and make-up air.
• AS 4254.1 / AS 4254.2 — sheet-metal and flexible duct construction (low/medium/high pressure to 2500 Pa).
• AS 3957 — design of localised exhaust ventilation and central dust extraction for hazardous dusts.
• AS 1375 — industrial fuel-fired appliances, furnaces and kilns (burner management, purge, flue).
• AS/NZS 60079.10.2 — classification of areas with combustible dust (Zone 20/21/22), carbon and graphite.
• AS 1530.4 — fire-resistance testing of building elements, fire-rated duct penetrations (250 °C/2 hour).
• AS/NZS 1715 / AS/NZS 1716 — respiratory protective equipment selection/use and equipment (silica and RCF PAPR).
• AS 2985 / AS 3640 — respirable (gravimetric) and inhalable dust sampling for exposure monitoring.
• AS 4024 — safety of machinery, guarding on dust-collection and access points.
• NCC Section J — energy efficiency (fan power, heat recovery, building fabric).
• ASHRAE 62.1 — outdoor-air ventilation rates (cross-reference for occupied office/control rooms).
• ISO 9001 / ISO 14001 / ISO 45001 — quality, environmental and OH&S management systems.
• NFPA 68 / NFPA 69 — deflagration venting and explosion prevention (cross-referenced for combustible carbon/graphite dust).

The governing workplace exposure standards (eight-hour time-weighted averages unless noted) for the refractory hazards are: respirable crystalline silica 0.05 mg/m3 (the dominant hazard, IARC Group 1 carcinogen); refractory ceramic fibre 0.5 fibres/mL (IARC Group 2B carcinogen, membrane-filter count); hexavalent chromium Cr(VI) 0.0003 mg/m3 as chromium (chrome refractory, confirmed carcinogen); coal-tar-pitch volatiles 0.2 mg/m3 benzene-soluble fraction (pitch/tar-bonded refractory, PAH carcinogen); graphite respirable 3 mg/m3 (carbon/graphite refractory, also combustible); alumina / aluminium oxide 10 mg/m3; magnesia (magnesium oxide) fume 10 mg/m3; nitrogen dioxide 3 ppm (5 ppm short-term peak) and sulfur dioxide 2 ppm (kiln combustion products); carbon monoxide 30 ppm; and carbon dioxide 5000 ppm.

21. Energy, kiln heat recovery and NCC Section J

A refractory plant is energy-intensive — the firing kilns alone consume enormous quantities of natural gas, and the building dissipates large quantities of heat that the HVAC system must manage. NCC Section J sets energy-efficiency requirements that bear on fan power, building-fabric performance and the recovery of waste heat, and a well-engineered refractory HVAC design treats the kiln exhaust as an energy resource rather than just a hazard to disperse.

Kiln heat recovery takes useful heat from the hot flue gas before it reaches the stack. Recuperators and heat exchangers on the kiln exhaust preheat combustion air (cutting gas consumption directly), preheat the drying-oven supply air, or provide space heating for the building in winter. The recovered-heat duct itself is part of the HVAC fabrication scope — high-temperature stainless on the hot side of the recuperator, transitioning to standard duct downstream — and the heat-recovery design has to be reconciled with the dilution and dispersion requirements (taking heat out of the exhaust lowers the stack temperature, which can reduce plume buoyancy and must be checked against the dispersion modelling for the EPA licence). Fan power is a significant operating cost in a plant moving the large air volumes that heavy dust extraction demands, so variable-speed drives, efficient fan selection and well-balanced low-resistance ductwork (smooth spiral, long-radius bends, minimal unnecessary fittings) all contribute to the Section J energy outcome and to the plant’s operating economics. The make-up air system, which tempers and delivers the large volumes the extraction removes, is a major energy consumer in its own right, and recovering kiln heat into the make-up air stream closes a useful energy loop.

22. Green Star, NABERS and the decarbonisation of refractory and green-steel

Sustainability rating and decarbonisation are reshaping the refractory sector and its facilities. Green Star (the Green Building Council of Australia rating for buildings and fit-outs) and NABERS (the National Australian Built Environment Rating System for operational energy and emissions) increasingly feature where refractory manufacturers build or refurbish facilities, and the HVAC system — its fan energy, its heat recovery, its make-up air efficiency — is a material contributor to the rating. A refractory plant that recovers kiln heat, runs variable-speed extraction and minimises duct resistance scores better and costs less to run.

The larger structural shift is the decarbonisation of the industries refractories serve, above all steel. The green-steel transition — the move from blast-furnace and basic-oxygen steelmaking toward electric-arc-furnace and direct-reduced-iron routes, including hydrogen-based reduction — changes the refractory demand profile. Electric-arc-furnace steelmaking uses magnesia-carbon and other basic refractories in different quantities and configurations than the integrated blast-furnace route, and the shift toward hydrogen direct reduction brings new high-temperature reduction-vessel refractory duties. For the refractory manufacturer this means evolving product mix; for the HVAC engineer it means the dust, fume and kiln-exhaust loads in the refractory plant shift with the product mix (more magnesia-carbon, for instance, means more combustible-carbon-dust duty), and the ventilation system has to be designed with enough flexibility to follow the change. Cement decarbonisation (alternative fuels, lower-clinker cements) similarly shifts the refractory demand from cement-kiln linings. The HVAC fabricator that understands where the refractory sector is heading designs duct systems that accommodate the coming product mix rather than just the current one.

23. Industry bodies, competitive positioning and the SBKJ approach

The Australian and international refractory sector is served by industry and standards bodies that frame the engineering and the regulation. The refractories industry internationally is represented by bodies such as the refractories trade associations and federations; in the materials and ceramics space the Australasian Ceramic Society and related professional bodies support the technical community; Standards Australia publishes the AS and AS/NZS standards cited throughout this guide; SafeWork Australia sets the workplace exposure standards and the model WHS framework that the state regulators (WorkSafe Victoria, SafeWork NSW, Workplace Health and Safety Queensland, WorkSafe WA) enforce; the state environment protection authorities license emissions; and ASHRAE and the broader HVAC engineering community provide the ventilation-engineering reference. The Air Conditioning and Mechanical Contractors Association (AMCA) and the broader Australian HVAC industry, gathering at ARBS, are the professional community within which the duct fabrication for these plants is designed and built.

Competitively, a refractory manufacturer or its mechanical contractor choosing a duct-fabrication partner is choosing between a generic commercial fabricator who treats the plant as ordinary ductwork and a fabricator equipped and experienced for the specific demands of refractory service. The difference shows in the first season of operation: the generic fabricator’s light-gauge galvanised dust main wears through, drops dust, leaks at the flanges and fails the air-monitoring test; the purpose-equipped fabricator’s heavy-gauge spiral main, welded where it must be hermetic and bonded, holds transport velocity, contains the carcinogen-grade streams, and passes. The SBKJ Group position is the second: an Australian machinery supplier based in Box Hill North VIC supplying the duct-fabrication machine line (SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600, SBTF-1500/1602/2020) that gives an Australian fabricator the production envelope to build refractory-grade duct correctly — abrasion-resistant heavy gauge for the dust mains, high-temperature stainless capability for the kiln exhaust, and continuous-weld capability for the RCF, pitch-PAH and combustible-dust containment. The machine line is the means; the engineering judgement in this guide is the context that lets a fabricator apply it to win and keep refractory work.

24. Accessibility, DDA and AS 1428.1 in the refractory facility

A refractory manufacturing facility is a workplace and, in its office, amenities and visitor areas, a building to which the Disability Discrimination Act (DDA) and the access provisions of the National Construction Code apply, with AS 1428.1 (design for access and mobility) setting the technical requirements. While the production floor of a heavy-industrial plant is governed primarily by the WHS and process-safety standards, the associated offices, control rooms, training rooms, amenities and any public-facing areas must meet the DDA and AS 1428.1 accessibility provisions — accessible paths of travel, doorways, sanitary facilities and the like. From the HVAC perspective the relevance is that the ventilation and conditioning of these accessible spaces (offices, control rooms, amenities) is part of the AS 1668.2 and ASHRAE 62.1 design scope and must deliver acceptable conditions in spaces that, in a refractory plant, sit adjacent to heavy heat and dust sources. The make-up-air and pressurisation strategy that keeps dust and fume out of the offices and control rooms is therefore both an exposure-control measure and an amenity measure, ensuring the accessible occupied spaces remain clean, comfortable and compliant.

25. Closing — SBKJ engineering support for Australian refractory manufacturing

The Australian refractory sector spans firebrick and kiln-furniture pressing, monolithic and castable bagging, refractory ceramic fibre manufacturing, pitch-bonded and carbon-bonded steel refractories, and chrome-bearing high-duty products — and every one of these processes generates a distinct and demanding HVAC load. Respirable crystalline silica at 0.05 mg/m3 is the dominant health hazard across the sector; refractory ceramic fibre at 0.5 fibres/mL, hexavalent chromium at 0.0003 mg/m3 and coal-tar-pitch volatiles at 0.2 mg/m3 add carcinogen-grade demands that leave no margin for a leaky or under-engineered duct system; the firing kilns at up to 1800 °C demand high-temperature stainless and engineered expansion joints; and the carbon and graphite refractory dust adds a combustible-dust explosion-protection chain. A duct system that is fabricated to match — heavy-gauge and abrasion-resistant for the dust mains, high-temperature stainless for the kiln exhaust, and continuously welded for the carcinogen and combustible containment — is the difference between a plant that holds its exposure standards and its EPA licence and one that does not.

The SBKJ Group engineering team in Box Hill North VIC is positioned to support Australian refractory manufacturers and their mechanical contractors with the duct-fabrication machine line (SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600, SBTF-1500/1602/2020), engineering documentation, commissioning support and ongoing technical advisory across every process zone described in this guide. We will be exhibiting at ARBS 2026 in Sydney in May with the full SBKJ machine portfolio plus refractory-specific reference samples covering heavy-gauge abrasion-resistant spiral dust mains, high-temperature kiln-exhaust transitions in 309/310S and Inconel 625, and continuously welded RCF and pitch-fume containment duct. Pre-show meetings with Australian refractory manufacturers, installers and their mechanical contractors are scheduled across the week.