Why glass plant HVAC is unlike any other industrial HVAC
A glass plant is a thermal monster. The melt furnace runs at 1500-1600 degrees Celsius, the gob shears drop molten glass at 1100-1200 deg C, and the annealing lehr slowly walks the formed product down from 540 deg C to 100 deg C over an hour. Heat is the visible part of the problem. The invisible part — and the one that governs every HVAC decision in the building — is respirable crystalline silica liberated from raw materials handling, refractory maintenance and cullet processing. Silicosis is a recorded occupational disease across the Australian glass industry going back to the 1950s, and Safe Work Australia's 2024 silica regulatory tightening has put glass-plant HVAC on the same compliance footing as engineered stone benchtop fabrication.
Layer onto that the chemistry: the float bath uses a reducing atmosphere of nitrogen plus 4-7 percent hydrogen over molten tin, the IS machine swabbing routine atomises graphite-based mould lubricant, the cold-end stearate spray coats every container with a slip layer, and the fibreglass insulation lines spray urea-formaldehyde binder onto freshly drawn fibres. Each one of those processes generates a dedicated airstream that has to be captured, conveyed and cleaned without contaminating the rest of the plant. Get the duct material wrong and you have galvanised duct corroding through inside 18 months from organic-acid breakdown of stearate residues. Get the pressure class wrong and a 1500 Pa batch house main flexes and unseats every Pittsburgh seam over a month of pulse-jet cycling.
This guide is the complete walk-through SBKJ engineers run with our customers — mechanical services contractors building dedicated duct fabrication shops to serve Australian glass plants on retrofit and shutdown projects. We cover the four glass production families separately, then merge into the cross-cutting topics: silica RCS control, materials selection, AS 1668.2 compliance, NFPA 654 combustible dust review, and where SBKJ machinery scope ends and welded heavy-gauge fabrication begins. The Australian glass industry runs lean and runs hot. The HVAC ductwork has to keep up.
The four glass production families
Glass manufacturing splits into four production families, each with a fundamentally different forming process and consequently a different HVAC duct loading profile. Australian operators are present in every family.
Container glass — bottles and jars
Container glass is the Coca-Cola bottle, the Penfolds wine bottle, the Vegemite jar and the Bickford's cordial bottle. Forming is done on the Individual Section (IS) machine: a row of 6, 8, 10 or 12 sections each running blow-and-blow or press-and-blow forming to deliver 100-300 containers per minute per section. The dominant Australian operator is O-I Australia (originally Owens-Illinois, restructured into the Visy Glass Recycling group from 2024), running plants in Adelaide (Glanville), Brisbane (Yatala) and Sydney (Penrith). Globally, Vitro and Verallia round out the major container glass groups.
The HVAC profile of a container plant is dominated by IS machine area heat load (radiant from gobs at 1100-1200 deg C plus furnace proximity), swabbing oil mist exhaust on every section, cold-end stearate spray coating exhaust at the lehr exit, and the standard batch house silica dust collection. Container plants typically run 400-600 lineal metres of HVAC ductwork between control rooms, operator pulpits, batch house and cold-end inspection.
Float glass — windows, mirrors, automotive glazing
Float glass is the Pilkington-pioneered process where molten glass at 1100 deg C is poured onto a bath of molten tin. The glass spreads to a uniform thickness, cools, and exits as a perfectly flat ribbon onto the lehr. Saint-Gobain Glass, AGC, Pilkington (NSG Group), Guardian and Vitro Architectural Glass dominate float globally. Australia has historically not run a float line domestically (most Australian flat glass is imported through Saint-Gobain Australia, Viridian and AGC distribution), but float glass processing — laminating, toughening and double-glazing — is a significant downstream Australian industry with substantial HVAC fit-out demand at facilities such as Viridian's Ingleburn NSW glass processing plant and the various automotive glass replacement workshops.
The HVAC profile of a float line, where present, is dominated by the float bath atmosphere control (reducing nitrogen-hydrogen blanket maintenance), tin-oxide condensation management on bath roof penetrations, and the very large lehr corridor (a float lehr can be 60-100 metres long). Stainless 304L is mandatory within 5 metres of the bath roof due to tin-oxide and sulfate condensation risk.
Fibreglass — insulation and reinforcement
Fibreglass splits cleanly into two sub-industries: insulation (loose-fill, batt, blanket and rigid board for thermal and acoustic insulation) and reinforcement (continuous filament for composite manufacturing). Insulation is the larger and more widespread of the two in Australia. The dominant operators are Bradford Insulation (a CSR brand running glass-wool batt manufacturing at Wagga Wagga NSW), Knauf Insulation Australia (Smithfield NSW operations), Owens Corning Australia (acoustic and thermal insulation distribution and limited fabrication) and Fletcher Insulation (loose-fill and batt). The reinforcement sector supplies the composite manufacturing industry — see the composite manufacturing HVAC duct guide for that side of the value chain.
The fibreglass insulation HVAC profile is dominated by fibre cabin heat removal (the drawing process generates substantial radiant heat), binder oven and cure-oven exhaust (urea-formaldehyde or low-formaldehyde binder thermal decomposition products at 180-260 deg C), and dust collection across the batt-cutting and packaging stations. 304L stainless is the default for binder oven exhaust runs.
Specialty glass — Pyrex, optical, lead crystal, Gorilla
Specialty glass covers borosilicate cookware (Pyrex, Schott), high-purity optical glass for telescopes (the Anglo-Australian Telescope at Coonabarabran NSW and the Sutherland Deep Space Station, both serviced by ANU's Mt Stromlo facility), strengthened glass for consumer electronics (Corning Gorilla Glass, Schott Xensation), lead crystal for tableware, ceramic glass cooktops and machinable glass-ceramic (Macor). Production volumes are small but specifications are extreme — optical glass for an 8-metre telescope mirror has to be cast and annealed over weeks with sub-micron temperature uniformity, and any HVAC airflow disturbance into the casting room is a project-killer.
Specialty glass HVAC profiles are dominated by ultra-clean cleanroom-grade supply air (often Class 10000 or better in optical casting halls), chemical exhaust for hydrofluoric acid polishing baths, and very tight temperature stability (plus or minus 0.5 deg C). 316L stainless and aluminium are common materials. SBAL-V machinery scope covers most specialty-glass HVAC duct fabrication; the chemistry-specific exhaust runs (HF polishing, ion-exchange chemical strengthening) are typically subcontracted to corrosion-specialist welded-fabrication shops.
The glass manufacturing process — what each zone does to the air
Before specifying duct, walk the process. A typical container glass plant has seven distinct HVAC zones, each with its own loading profile.
Zone 1 — Batch house
The batch house receives raw materials by truck or rail: silica sand, soda ash (sodium carbonate), limestone, dolomite, feldspar, salt cake (sodium sulfate), iron oxide colourants and recycled cullet. Raw materials are weighed, mixed and conveyed to the furnace charging end. Every transfer point — bag dump, hopper transfer, conveyor handover, mixer charge, mixer discharge — generates a dust plume. Silica sand is the dominant respirable crystalline silica source. Source-capture local exhaust hoods at every transfer connect to a baghouse with PTFE membrane filter media, returning collected dust to the batch hopper or to inert-waste disposal. The personnel-zone HVAC for the batch house operator (the blending controller) targets 24-26 deg C with positive pressure to keep dust from migrating into the control booth.
Batch house HVAC duct length runs 200-400 lineal metres for a typical container glass plant, all in galvanised G90 (Z275) for general HVAC and 1.0-1.2 mm galvanised for source-capture mains. Pressure class C (up to 2500 Pa) on the dust mains, class A-B on personnel comfort runs.
Zone 2 — Furnace
The melt furnace is a regenerative or recuperative cross-fired or end-fired furnace at 1500-1600 deg C melting temperature. Combustion is natural gas or oil-fired (some plants are converting to oxy-fuel for emissions reduction, and a few R&D installations are testing electric and hydrogen firing). The furnace is the heart of the plant and the largest single source of NOx and SOx emissions. Furnace process exhaust — the regenerator stack flue gas at 350-450 deg C after heat recovery — sits firmly outside any standard duct machinery scope. That exhaust stream uses 1.5-3.0 mm welded mild steel or refractory-lined plate fabricated by submerged-arc welding shops with ASME Section IX qualified procedures, fitted with selective catalytic reduction (SCR) for NOx and electrostatic precipitator or wet scrubber for particulate.
What is within HVAC duct machinery scope is the personnel-zone ambient HVAC around the furnace: the hot-end operator pulpit (refrigerated supply air at 26-28 deg C), the electrical room serving the furnace combustion controls (positive pressure, 22-24 deg C, Class III filtration), and the maintenance corridor between the furnace wall and the IS machine area (general ventilation 10-12 ACH). All of those runs are SBAL-V scope in galvanised, with selective use of 304L stainless on returns within 3 metres of furnace wall radiant exposure.
Zone 3 — Forming
Forming differs by glass type. For container glass it is the IS (Individual Section) machine: rows of 6-12 sections each performing blow-and-blow or press-and-blow forming. For float glass it is the float bath, where molten glass spreads on molten tin under a reducing nitrogen-hydrogen atmosphere. For fibreglass insulation it is the rotary spinner cabin, where centrifugal force pulls molten glass through a perforated spinner into fibre. For continuous filament reinforcement it is the bushing array, where molten glass flows through a precision platinum-rhodium bushing plate.
The IS machine area is the most HVAC-intensive forming zone. Ambient temperatures hit 40-50 deg C without active cooling because of radiant heat from gobs at 1100-1200 deg C and the open furnace charging end nearby. Personnel cooling at the operator pulpit targets 26-28 deg C through filtered refrigerated supply at 8-12 ACH, delivered via insulated galvanised SBAL-V supply duct. Each IS section has a swabbing routine where a graphite-based mould lubricant is applied — the swabbing oil mist is captured at the source through a local exhaust hood at 1.0-1.5 m/s face velocity, conveyed in 304L stainless duct to a dedicated mist eliminator and roof stack.
Zone 4 — Annealing lehr
The annealing lehr is a slow-cooling tunnel oven that walks the formed product from approximately 540 deg C inlet down to 100 deg C outlet over 60-90 minutes residence time. Annealing relieves residual thermal stress, without which the product would shatter on first temperature cycle. Lehr exhaust gases are mid-temperature (200-300 deg C) with low organic content unless cold-end coating is applied at the lehr exit. The lehr stack itself is welded mild steel, outside standard duct machinery scope.
What is within scope is the personnel-zone HVAC for the lehr corridor: a 30 deg C ambient maximum target at occupied workstations through 6-8 ACH ventilation, delivered via SBAL-V galvanised supply ductwork. The cold-end transition from lehr exit to inspection station may require local exhaust capture for any cold-end coating overspray.
Zone 5 — Inspection
Cold-end inspection scans every container or sheet for stress fringes, dimensional defects, surface contamination and inclusions. Inspection stations run automated optical and dimensional sensors with a small number of human inspectors performing audit sampling. Personnel HVAC targets 22-24 deg C ambient with positive pressure (Class III filtration) to keep cullet dust from migrating into the inspection zone. SBAL-V galvanised supply, SBTF spiral round return air mains where corridor lengths permit.
Zone 6 — Decoration and coating
Decoration is silk-screen printing, enamel coating, fluoropolymer coating and decoration bake oven curing. The processes use solvent-based or water-based inks and paints with significant VOC content. AS 1668.2 Section 6 and state EPA licences mandate VOC capture and abatement (typically activated carbon adsorption for low VOC streams or thermal oxidation for high VOC streams). Down-draft booth construction uses galvanised SBAL-V plenum walls. Bake oven exhaust at 400-500 deg C uses 1.5 mm welded mild steel and sits outside SBKJ machinery scope.
Zone 7 — Packaging and warehouse
Packaging wraps cooled product onto pallets, applies stretch-wrap and labels, and stages for despatch. Personnel HVAC targets 22-26 deg C through general ventilation 4-6 ACH. Light dust loading from cardboard and plastic film. SBAL-V galvanised throughout, SBTF spiral round return mains. Warehouse zones are typically unconditioned beyond ventilation per AS 1668.2 Section 5.
Australian glass operators — the specifying engineers
Knowing which operators specify what informs how an HVAC duct fabrication shop sizes its capacity. The Australian glass landscape is concentrated.
O-I Australia / Visy Glass Recycling
O-I Australia (formerly Owens-Illinois) is the country's largest container glass operator, running plants in Adelaide (Glanville SA), Brisbane (Yatala QLD) and Sydney (Penrith NSW). The 2024 restructure placed O-I Australia under the Visy Glass Recycling umbrella, integrating cullet recycling with container production. The plants run multiple IS machine lines producing wine bottles, beer bottles, food jars and pharmaceutical containers. Major customers include Penfolds, Coopers, Treasury Wine Estates, Bickfords and Lion Beverages.
HVAC retrofit projects at O-I Australia plants typically tender to mechanical services contractors during planned shutdown windows (each plant runs a 4-6 week major shutdown every 8-12 years for furnace rebuild, with smaller 1-2 week shutdowns annually). The duct scope is split: mechanical services contractor handles all personnel-zone HVAC and source-capture hoods; specialist welded-fabrication contractor handles furnace stack and lehr stack heavy-gauge work.
Saint-Gobain Australia
Saint-Gobain Australia covers two large Australian operations: the gypsum business (operating through CSR/Boral subsidiary structure) and the insulation business (formerly trading as INSULSAFE). Saint-Gobain's flat glass and laminate processing operations in Australia are smaller than the European and North American footprint, with most flat glass imported through Viridian distribution.
HVAC retrofit demand at Saint-Gobain Australia operations is concentrated on the gypsum and insulation manufacturing facilities, where binder oven exhaust, cure oven exhaust and dust collection on the batt-cutting lines are the primary scope items. SBKJ has supplied SBAL-V auto duct lines to mechanical services contractors fabricating duct for Saint-Gobain Australia projects, with deliveries through the Sydney and Melbourne ports.
Bradford Insulation
Bradford is a CSR-owned brand running the Wagga Wagga NSW glass-wool insulation manufacturing facility, supplying batts and rolls into the Australian residential and commercial construction market. Bradford's plant runs continuous fibre drawing, binder spray, oven curing and packaging — a classic fibreglass insulation HVAC profile.
The Wagga plant uses 304L stainless duct on binder oven exhaust runs and galvanised on personnel HVAC and dust collection. SBKJ machinery has been supplied to Bradford's mechanical services contractors for in-house duct fabrication.
Knauf Insulation Australia
Knauf Insulation Australia operates from Smithfield NSW with a fibreglass insulation manufacturing capability serving the Australian residential, commercial and industrial insulation market. The plant runs a low-formaldehyde binder system (ECOSE Technology globally) which reduces but does not eliminate the binder exhaust HVAC requirement. 304L stainless duct on cure-oven exhaust, galvanised on personnel HVAC.
Owens Corning Australia
Owens Corning's Australian footprint focuses on acoustic and thermal insulation distribution and limited fabrication. While the major fibreglass insulation manufacturing for Owens Corning is run from facilities outside Australia, the Australian operations include conversion fabrication that requires personnel-zone HVAC and dust-collection ductwork. SBAL-V machinery scope covers the full Australian Owens Corning HVAC duct demand.
Visy Glass Recycling — cullet processing
Visy Glass Recycling, integrated with O-I Australia from 2024, is the dominant cullet processing operator in Australia. Cullet is recycled bottle glass crushed, cleaned, sorted by colour and reintroduced to the batch hopper at typically 30-70 percent of the batch (the higher percentage drives lower furnace energy consumption). Cullet processing plants in Sydney (Smithfield), Brisbane (Wacol) and Melbourne (Reservoir) run crushing, washing, optical sorting and magnetic separation lines.
The cullet HVAC profile is dominated by dust collection at every crushing and screening transfer (silica RCS plus organic-residue dust from labels, plastic closures and any food residue not fully removed in washing). NFPA 654 combustible-dust review is mandatory at every cullet processing zone with dust loading above 0.4 mm layer thickness, because the organic residue creates a deflagration hazard absent in pure raw-material batch handling. Lithium-ion battery contamination of cullet streams is an emerging concern — small consumer batteries entering the cullet line can ignite organic dust and have caused multiple plant fires globally since 2022.
Standards and regulatory framework
Glass plant HVAC sits at the intersection of multiple Australian and international standards. The five most important are listed below.
AS 1668.2-2024 — mechanical ventilation
AS 1668.2 The use of mechanical ventilation and air-conditioning in buildings is the master Australian standard for the design of mechanical ventilation systems in occupied buildings. Section 5 covers general exhaust ventilation, Section 6 covers specific exhaust applications (kitchens, laboratories, manufacturing processes, paint spray booths, semiconductor fabrication etc.), and Annex A through G provide application-specific guidance. Most HVAC ductwork in Australian glass plants is governed by Section 5 (personnel zones) and Section 6 (dust collection, decoration room exhaust). Pressure classes and air-tightness requirements cross-reference AS/NZS 4254.2.
AS/NZS 4254.2 — duct construction
AS/NZS 4254.2 Ductwork for air-handling systems in buildings — Rigid duct sets the construction requirements for sheet metal ductwork, including pressure class A through E (up to 2500 Pa positive, lower negative limits), air-tightness leakage classes, reinforcement schedules, gauge selection and seam types. Pittsburgh seam construction satisfies pressure class A-C; longitudinal seam welding is required for class D-E and for any leak-class A air-tightness on stainless. SBKJ SBAL-V auto duct line output meets AS/NZS 4254.2 pressure class C up to 2500 Pa as standard on Pittsburgh seam.
OSHA 29 CFR 1910.1053 and ACGIH TLV — respirable crystalline silica
The OSHA Permissible Exposure Limit for respirable crystalline silica is 0.05 mg/m3 as an 8-hour time-weighted average (TWA), enforceable in US workplaces and used as a reference benchmark in Australian glass plants. The ACGIH Threshold Limit Value is more conservative at 0.025 mg/m3 8-hour TWA. Safe Work Australia's national workplace exposure standard for crystalline silica (quartz) is 0.05 mg/m3 8-hour TWA, with the engineering control hierarchy (substitution, isolation, local exhaust ventilation, then PPE) mandated as the design approach. The 2024 silica regulatory update tightened exposure monitoring frequency and respiratory health surveillance requirements.
NFPA 654 — combustible dust
NFPA 654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids governs deflagration risk assessment and engineering controls for combustible dust. Pure silica sand, soda ash and limestone are non-combustible and exempt. Cullet processing zones with organic contamination (label paper, plastic closures, food residue) fall within NFPA 654 scope at dust layer thickness above 0.4 mm. Engineering controls include explosion vents on baghouse hoppers, isolation valves between dust collectors and process equipment, and electrostatic grounding on all duct and equipment.
NFPA 86 — industrial ovens and lehrs
NFPA 86 Standard for Ovens and Furnaces governs combustion safety and exhaust design for fuel-fired ovens. Glass annealing lehrs at the larger end of the size range fall within NFPA 86 scope, although most Australian glass plants follow AS 4041 piping code and AS 1228 boiler code in parallel. Lehr exhaust design — purge volume, combustion-safety interlocks, exhaust stack sizing — is governed by NFPA 86 Chapter 8.
AS 4655 — alternative dust collector
AS 4655 Fire safety in waste recycling and recovery facilities — General principles addresses fire safety in waste handling but is increasingly cross-referenced for cullet processing dust collection at glass-recycling facilities. The standard covers fire detection, suppression and explosion venting on alternative dust-collection equipment.
AS 3640 and AS NZS 60079.10 — dust hazardous area zoning
AS 3640 Workplace atmospheres — Method for sampling and gravimetric determination of inspirable dust governs the personal monitoring methodology for silica RCS exposure assessment. AS/NZS 60079.10 series covers electrical equipment in explosive atmospheres, with Part 10.2 specifically covering combustible dust atmospheres (hazardous area zone classification 20, 21 and 22 for dust). Cullet processing baghouse interiors typically classify Zone 20.
Batch house HVAC — the silica problem
The batch house is the highest-RCS-exposure zone in any glass plant and the area where HVAC design errors carry the highest occupational health consequence. Engineering control hierarchy applied to the batch house translates directly into duct design.
Source-capture local exhaust ventilation
Every dust-generating point in the batch house gets a dedicated local exhaust hood: bag dump station, weigh hopper inlet and discharge, mixer charge port, mixer discharge chute, conveyor transfer points (head pulley discharge, tail pulley feed), pneumatic conveying receiver and any bin vent. Capture velocity at the source is 1.5-2.5 m/s per ACGIH Industrial Ventilation Manual. Hood design (lateral exhaust on bag dump, downdraft on weigh hopper, enclosure on mixer) is selected by the dust loading and operator access requirement.
Hood transitions from capture point to trunk duct typically run 1.0-1.2 mm galvanised — heavier than standard HVAC galvanised because of abrasion from silica-loaded airstreams. Trunk duct sizing is dictated by transport velocity: minimum 18-22 m/s on horizontal runs to keep silica entrained, dropping to 15 m/s on vertical risers. Trunk duct is standard 0.7-1.0 mm galvanised on Pittsburgh seam, all SBAL-V scope.
Baghouse with PTFE membrane media
The baghouse is the primary collection device. Pulse-jet baghouse construction with PTFE membrane media (W.L. Gore Gore-Tex membrane bonded to a polyester or fibreglass substrate is the industry default) at 1.0-1.5 m/min air-to-cloth ratio is standard for silica service. The PTFE membrane provides surface filtration (particles released cleanly on pulse) and resists blinding by fine silica. Baghouse efficiency at the membrane is typically 99.99 percent removal at 0.5 micron, satisfying the OSHA RCS PEL on the discharge stack.
Baghouse inlet duct runs 1.0-1.2 mm galvanised. Hopper isolation valve isolates the baghouse from the upstream process during filter changeout. Explosion vent on the hopper roof per NFPA 654 if the dust loading falls within combustible-dust scope (rare for pure silica, common for cullet dust collection).
Personnel zone HVAC
Adjacent to the dust collection system is the batch house operator zone — a control booth or pulpit where the blending operator monitors the recipe and runs the batch sequence. Personnel zone HVAC targets 24-26 deg C ambient with positive pressure (Class III filtration to F7 grade or better) to keep silica dust from migrating into the booth. Supply air at 8-10 ACH through insulated galvanised SBAL-V supply duct, return through ceiling diffusers into the SBTF spiral return main back to the supply air handler.
Door interlocks on the booth ensure positive pressure is maintained when the operator enters or exits. Pressure indicator on the booth wall gives the operator visual confirmation of pressure status. Filter pressure differential alarm warns when the F7 filter is approaching change-out.
Furnace HVAC — what is and is not in scope
The melt furnace is the largest single piece of equipment in the plant and the largest single emissions source. HVAC duct scope around the furnace splits into two strict categories.
Process exhaust — outside SBKJ machinery scope
The furnace combustion exhaust — the regenerator stack flue gas at 350-450 deg C after heat recovery — sits firmly outside any standard sheet metal duct machinery scope. The duct is 1.5-3.0 mm welded mild steel or refractory-lined plate, fabricated by submerged-arc welding shops with ASME Section IX qualified procedures and heat-stress relief on completed assemblies. The exhaust train includes selective catalytic reduction (SCR) for NOx control, bag filter or electrostatic precipitator for particulate, and acid-gas scrubber where required by state EPA licence. Lifecycle is 15-20 years between major rebuilds.
Why is this outside HVAC duct machinery scope? Three reasons. First, material thickness: SBAL-V handles up to 1.5 mm and the SBKJ duct welding line up to 1.6 mm — heavy-gauge furnace exhaust at 1.5-3.0 mm needs plate rolling and submerged-arc welding capability that sits in a different equipment class. Second, temperature: standard duct construction is rated to 80 deg C continuous; furnace exhaust at 350-450 deg C requires bellows expansion joints, refractory lining and fully welded construction. Third, qualification: pressure-bearing assemblies at high temperature need ASME Section IX qualified welders and weld procedure specifications, not the standard Pittsburgh-seam fabrication that sheet metal duct machines support.
Personnel zone HVAC around the furnace — within SBKJ machinery scope
What is within SBKJ machinery scope is the ambient HVAC around the furnace. The hot-end operator pulpit (a small control booth on the furnace charging end) needs filtered refrigerated supply air at 26-28 deg C through insulated galvanised supply duct. The electrical room serving the furnace combustion controls needs positive pressure HVAC at 22-24 deg C with Class III filtration. The maintenance corridor between the furnace wall and the IS machine area needs general ventilation at 10-12 ACH for personnel access during shift handover.
All of those runs are SBAL-V galvanised SCOPE — typical lengths 80-150 lineal metres of mixed rectangular and spiral construction per furnace serving zone. 304L stainless return-air specified within 3 metres of furnace wall radiant exposure due to heat ageing of zinc galvanising at sustained surface temperature above 80 deg C.
Float bath ventilation — the tin atmosphere
The float bath is the defining feature of float glass production and presents HVAC challenges that no other glass production family encounters. The bath is a long shallow tank of molten tin (typically 50 metres long, 10 metres wide, 50-150 mm deep tin layer), maintained under a reducing atmosphere of nitrogen plus 4-7 percent hydrogen to prevent tin oxidation. Molten glass at 1100 deg C floats on the tin surface and spreads to a uniform thickness. Glass exits at 600 deg C onto the lehr.
Atmosphere control
The reducing atmosphere is maintained by a continuous nitrogen-hydrogen feed, with seal mechanisms at the glass entry and exit preventing air ingress. Bath roof penetrations (for thermocouples, gas sample probes, top heater elements and visual inspection ports) are sealed with refractory bushings and ceramic-fibre packing. Despite the seals, small atmospheric leakage occurs and tin vapour from the bath surface condenses on cooler roof surfaces as tin oxide and tin sulfate deposits.
Tin oxide and tin sulfate are corrosive to galvanised steel. Within 5 metres of the bath roof, all return-air duct and any local exhaust capture for atmospheric maintenance discharge use 304L stainless. Beyond 5 metres, galvanised is acceptable. The transition point is normally at the float bath enclosure wall.
Ambient HVAC for the bath corridor
Personnel access to the float bath is via a corridor running the bath length. Ambient HVAC targets 32 deg C maximum at occupied workstations through 8-10 ACH ventilation. Supply air through insulated galvanised SBAL-V supply duct delivered at 4-metre intervals along the corridor. Return air at the corridor end into a 304L stainless main that traverses through the bath enclosure to the exhaust fan room. Roof exhaust hood over the bath edge captures any escaping reducing gas through 304L SBAL-V duct.
Tin pollution control
Float plant emissions licences typically include a tin emissions limit (10-50 micrograms per cubic metre at the boundary). Bath enclosure exhaust is treated through a wet scrubber or a bag filter sized for tin oxide particulate before discharge to atmosphere. The tin abatement train is typically welded-fabrication scope.
Container glass IS machine HVAC
The IS (Individual Section) machine is the workhorse of container glass production. A row of 6, 8, 10 or 12 sections each running blow-and-blow or press-and-blow forming delivers 100-300 containers per minute per section to the lehr. The IS machine area is the most HVAC-demanding zone in a container plant.
Heat load
Radiant heat from gobs at 1100-1200 deg C, plus convective heat from the open furnace charging end, plus heat from the moulds (mould temperature 500-600 deg C operating), pushes ambient temperature to 40-50 deg C without active cooling. Workstations along the IS machine row need to be cooled to 28 deg C maximum at the operator standing position.
Operator pulpit
The IS machine operator pulpit is an enclosed or semi-enclosed booth running parallel to the IS machine row, typically 8-15 metres long. Filtered refrigerated supply air at 8-12 ACH delivered to the pulpit through insulated galvanised SBAL-V supply duct (50 mm of fibreglass insulation between inner and outer galvanised skins). Internal liner provides thermal break and prevents condensation on the inner duct surface. Return air through the pulpit ceiling into the SBTF spiral round return main.
Swabbing oil mist exhaust
Each IS section runs a swabbing routine every 4-8 hours where a graphite-based mould lubricant is applied to the blank mould and the blow mould to maintain release performance. The lubricant is sprayed under low pressure and the atomisation generates an oil mist that, uncontrolled, drifts through the IS machine area and condenses on every cool surface (ductwork, electrical panels, walkways) as a sticky black film.
Swabbing oil mist capture uses a local exhaust hood positioned over each section's swabbing access point, sized at 1.0-1.5 m/s face velocity. Hood material 1.2 mm 304L stainless because of the corrosive organic-acid breakdown products of the graphite lubricant at elevated temperature. Trunk duct conveying the captured mist to the mist eliminator and roof stack is 304L stainless 1.0 mm SBAL-V scope. Trunk velocity 12-15 m/s to keep oil droplets entrained without excessive pressure drop.
Section-to-section airflow management
The IS machine row is open on both sides for operator access. Cross-flow drafts can disrupt the gob delivery from the gob distributor to the section feeder, causing forming defects. HVAC supply air to the operator pulpit should be designed to prevent cross-flow drafts above 0.5 m/s at the gob delivery height. Diffuser selection and supply air velocity profile become critical.
Annealing lehr HVAC
The annealing lehr is a slow-cooling tunnel oven running container or flat-glass product through a controlled temperature profile from approximately 540 deg C at the inlet down to 100 deg C at the outlet. Residence time is 60-90 minutes for containers and longer for thick flat glass. Annealing relieves residual thermal stress.
Lehr exhaust — outside SBKJ machinery scope
Lehr exhaust gas at 200-300 deg C exits through a roof stack. Lehr stack construction is welded mild steel or 304L stainless at 1.5-2.0 mm thickness, fabricated by welded-fabrication shops. Stack height and velocity are sized to satisfy state EPA dispersion modelling. Lehr exhaust is mid-temperature work, but the welded construction sits outside SBKJ standard machinery scope.
Lehr corridor personnel HVAC — within SBKJ machinery scope
The lehr corridor — the walkway running parallel to the lehr exterior — needs personnel HVAC at 30 deg C maximum ambient through 6-8 ACH ventilation. Lehr exterior wall surface temperature drops from approximately 60 deg C at the inlet end to 35 deg C at the outlet end, providing a mild radiant heat load on the corridor.
Supply air through galvanised SBAL-V insulated supply duct at 4-metre spacing along the corridor. Return air at the lehr-outlet end (cold-end) into the SBTF spiral round return main. Total corridor HVAC duct length 60-150 lineal metres for a 30-50 metre lehr. All within SBAL-V machinery scope.
Cold-end coating overspray capture
Where cold-end coating is applied at the lehr exit (stearate slip coating for containers, fluoropolymer for some specialty products), local exhaust capture at the spray hood prevents overspray contamination of downstream inspection. Capture face velocity 1.0-1.5 m/s. Hood material 1.0-1.2 mm 304L stainless because galvanised will corrode from organic-acid breakdown of stearate residues. Trunk duct 304L stainless SBAL-V scope discharging through a HEPA-grade pre-filter and HVAC-grade activated carbon for VOC compliance.
Cold-end stearate coating exhaust
Container glass receives a two-stage coating: hot-end (tin oxide or titanium oxide deposition at 500-600 deg C as the container exits the IS machine) and cold-end (stearate slip coating at 80-100 deg C as the container exits the lehr). The stearate coating reduces friction between containers on the conveyor and prevents scuffing. Stearate is sprayed as a fine atomised mist over the moving containers.
Stearate coating exhaust capture is critical. Uncontrolled stearate overspray coats every surface in the cold-end inspection area as a slippery white film, becomes a slip hazard on walkways, and degrades inspection optical clarity. Capture is via a local exhaust hood over the spray station at 1.0-1.5 m/s face velocity, conveying through 304L stainless duct (SBAL-V scope at 1.0-1.2 mm) to a HEPA-grade pre-filter for particulate removal and an activated carbon bed for VOC compliance. Discharge to atmosphere through a roof stack.
Material selection matters. Stearate is an organic fatty-acid compound. At elevated temperature in the exhaust stream, breakdown products include free fatty acids, ketones and aldehydes. Galvanised duct corrodes through within 12-18 months in this service. 304L stainless is the only economic choice. Aluminium fails on chloride attack from any chloride contamination of the stearate. The SBAL-V auto duct line forms 304L stainless from 0.6 to 1.5 mm with no tooling change, making cold-end coating duct fabrication a standard SBKJ machinery scope item.
Fibreglass production HVAC
Fibreglass insulation production runs three distinct HVAC zones beyond the standard furnace and personnel zones: fibre cabin heat removal, binder coating exhaust, and dust collection on batt-cutting and packaging.
Fibre cabin
The fibre cabin is where molten glass at 1100 deg C is centrifugally drawn through a perforated rotary spinner to produce fibre. The cabin is partially enclosed to contain fibre overspray and is hot — typically 60-80 deg C ambient depending on production rate. Cabin ventilation extracts the radiant heat and any fibre fragments that escape the spinner. Capture flow rate is sized at 12-20 ACH depending on cabin volume. Duct material 304L stainless 1.0-1.2 mm because of fibre abrasion and the elevated temperature; SBAL-V scope.
Binder coating exhaust
Immediately downstream of the fibre cabin, binder is sprayed onto the freshly drawn fibre to bond fibres into a coherent mat. Traditional binder is urea-formaldehyde resin; modern alternatives include the Knauf ECOSE Technology bio-based binder which significantly reduces formaldehyde emissions but does not eliminate VOC exhaust requirements. Binder spray booth uses downdraft construction with capture face velocity 1.0-1.5 m/s.
Binder spray exhaust is conveyed through 304L stainless duct (SBAL-V scope at 1.0-1.5 mm) to a wet scrubber for formaldehyde removal followed by a thermal oxidiser or activated carbon bed for residual VOC. Discharge stack tested per state EPA licence. Duct lengths 40-80 lineal metres per spray booth.
Cure oven exhaust
Downstream of binder spray, the binder-coated fibre mat passes through a cure oven at 180-260 deg C to crosslink the binder. Cure oven exhaust contains formaldehyde, ammonia and partially-cured binder volatiles. Cure oven exhaust duct is 304L stainless at 1.0-1.5 mm, SBAL-V scope, conveyed to the same scrubber-thermal-oxidiser train as the spray exhaust. Cure oven exhaust temperature 200-260 deg C is at the upper end of SBAL-V scope; insulated double-skin construction prevents external surface temperature exceeding 60 deg C personnel safety limit.
Batt cutting and packaging dust collection
Cured fibre mat is cut to batt dimensions, edge-trimmed and packaged. Cutting and trimming generate fibreglass dust that is captured at every saw and trimmer through local exhaust hoods conveying to a baghouse. Galvanised SBAL-V scope for hood-to-baghouse mains; pulse-jet baghouse with polyester felt media at 1.5-2.0 m/min air-to-cloth ratio. Discharge to atmosphere through a HEPA-grade final filter.
Specialty glass production HVAC
Specialty glass production is the smallest of the four families by volume but the most demanding by HVAC specification. Each sub-segment has different requirements.
Borosilicate cookware (Pyrex, Schott)
Borosilicate cookware is press-formed in a process similar to container press-and-blow, but at lower temperature (1500 deg C melt, 950-1050 deg C forming) and with longer annealing times due to the lower thermal expansion coefficient. Production volume in Australia is small; most borosilicate cookware sold in Australia is imported through Corning and Schott distribution. Where production is run, the HVAC profile mirrors container glass with adjustment for the lower forming temperature.
Optical glass (telescope mirrors, lenses)
Optical glass production is small-batch and ultra-precision. The Anglo-Australian Telescope at Coonabarabran NSW (operated under ANU's Mt Stromlo facility) and similar precision optics installations require optical glass cast and annealed under sub-micron temperature uniformity. HVAC into the casting room must not introduce thermal gradients. Cleanroom-grade construction (Class 10000 or better) using galvanised SBAL-V plenum walls and HEPA filtered supply air.
Optical glass annealing can run weeks per casting. Any HVAC fault during the anneal scrap-rates the casting, with replacement cost in seven figures for an 8-metre telescope mirror. HVAC redundancy (N+1 supply fans, dual chillers, UPS power on critical loads) is mandatory.
Strengthened consumer glass (Gorilla Glass, ion-exchange)
Strengthened consumer glass — Corning Gorilla Glass for smartphone screens, Schott Xensation for watch crystals — is produced by the fusion-draw or float process and chemically strengthened by ion exchange in molten potassium nitrate at 380-420 deg C. The ion-exchange bath is the key HVAC zone. Salt spray and condensation generate corrosion risk on adjacent ductwork. 316L stainless duct (better than 304L for chloride resistance) in the ion-exchange room, SBAL-V scope at 1.0-1.5 mm.
Lead crystal tableware
Lead crystal — high-lead-oxide content glass for premium tableware (Waterford, Baccarat, Riedel) — is hand-blown or press-formed in small-volume production. The lead oxide adds occupational health complexity: airborne lead particulate from grinding and polishing requires HEPA-grade local exhaust capture. Galvanised SBAL-V scope for the local exhaust hoods, with HEPA discharge filtration before atmospheric release. Lead-content production in Australia is currently limited.
Cullet recycling — the emerging fire risk
Cullet recycling — crushing, washing, optical sorting and reintroducing recycled bottle glass to the batch hopper — is the dominant industrial counterweight to virgin silica sand demand in container glass. Visy Glass Recycling operates Australia's largest cullet processing footprint, integrated with O-I container production from 2024. Cullet is reintroduced at 30-70 percent of the batch, depending on furnace capability.
Lithium-ion battery contamination
The major emerging concern in cullet processing is lithium-ion battery contamination. Small consumer batteries (vape devices, hearing aids, button cells) inadvertently entering recycling streams alongside bottle glass have caused multiple plant fires globally since 2022. A single damaged Li-ion cell in a cullet crusher can release thermal energy sufficient to ignite organic dust (label paper, plastic closures, food residue) above the cullet stream, propagating a fire through the conveyor system into the baghouse.
HVAC implications: cullet processing zones now require fire detection (infrared spot detectors and continuous CO monitoring) integrated with the dust collection system, automatic dampering to isolate the baghouse on fire signal, and explosion venting on the baghouse hopper per NFPA 654. Duct material on cullet-processing source-capture mains may upgrade from galvanised to galvanised with Intumescent fire-rated coating where insurance requirements demand.
NFPA 654 review for cullet zones
Cullet processing zones with organic-residue dust loading above 0.4 mm layer thickness fall within NFPA 654 scope. Required engineering controls include explosion vents on baghouse hoppers (sized per NFPA 68), isolation valves between the dust collector and process equipment to prevent flame propagation, electrostatic grounding on all duct and equipment, and dust-tight construction on duct seams.
Worker silica exposure — medical surveillance and engineering controls
Respirable crystalline silica is the dominant occupational health hazard in glass plant operations. Beyond the engineering controls embedded in the HVAC design, the regulatory framework requires personal monitoring, medical surveillance and respiratory health screening.
Personal monitoring
AS 3640 governs personal monitoring methodology. Workers in batch house, cullet processing and any maintenance zone where silica-containing brick or refractory is handled wear personal sampling pumps for an 8-hour shift, sampling onto pre-weighed PVC filters at a controlled flow rate (typically 1.7-2.2 L/min through a respirable-fraction cyclone sampler). Filters are gravimetrically analysed and the silica fraction quantified by X-ray diffraction or FTIR.
Monitoring frequency: baseline survey on commencement, then at least annually for any worker assigned to a silica-exposure role, with increased frequency where engineering controls are modified or where peak exposure is suspected. Record retention 30 years per Safe Work Australia silicosis health monitoring requirements.
Medical surveillance
AS 2865 covers confined space entry and is referenced for some glass plant maintenance access (furnace and lehr internal inspection). Safe Work Australia's silicosis exposure standards mandate health surveillance for all workers in roles with foreseeable silica exposure: pre-placement examination, periodic chest imaging (low-dose CT preferred over plain chest X-ray for silicosis screening from 2024 onwards), and pulmonary function testing.
Respiratory protection
PPE is the last line of defence after engineering controls. RPE selection per AS/NZS 1715. Powered air-purifying respirators (PAPR) with P3 cartridge are typical for batch house operations where engineering controls are operating; supplied-air respirators for furnace internal access and other very high exposure activities.
Materials selection for glass plant HVAC duct
Material selection drives both initial cost and lifecycle cost. Glass plant HVAC sees four main material classes.
Galvanised G90 (Z275)
Galvanised G90 (276 g/m2 zinc coating per ASTM A653, equivalent to AS/NZS Z275) is the workhorse material for general HVAC duct in glass plants. Acceptable for personnel-zone supply and return, dry batch house source-capture mains, lehr corridor HVAC, packaging area HVAC, control rooms and electrical rooms. Limited to 80 deg C continuous service. Not suitable for stearate exhaust, formaldehyde exhaust, tin-bath proximity or any humid/corrosive forming-area run. Forms readily on the SBAL-V auto duct line at 0.5-1.5 mm.
304L stainless
304L stainless is the default upgrade material for any service that exceeds galvanised limits. Cold-end stearate coating exhaust, IS machine swabbing oil mist, float bath proximity (within 5 m of bath roof), fibreglass binder oven exhaust, fibreglass cure oven exhaust, container glass hot-end coating exhaust. 304L is preferred over 304 for welded fabrication because of reduced sensitisation risk during welding, although standard SBAL-V Pittsburgh-seam construction does not require 'L' grade. Forms readily on SBAL-V at 0.6-1.5 mm and on SBTF spiral tubeformer at 0.6-1.5 mm.
Fibreglass-reinforced plastic (FRP)
FRP duct is occasionally specified for very humid forming-area runs where stainless cost is prohibitive and temperature is below 80 deg C. FRP has good corrosion resistance, low thermal conductivity (no condensation on outer surface) and acceptable strength on properly designed flange systems. Outside SBKJ machinery scope — FRP is fabricated by hand lay-up or filament winding at specialist composite shops. See the composite manufacturing HVAC duct guide for FRP fabrication.
Mild steel (welded heavy gauge)
Mild steel at 1.5-3.0 mm thickness with welded fabrication is reserved for high-temperature furnace exhaust, lehr stack exhaust and decoration room bake-oven exhaust. Outside SBKJ standard machinery scope. Fabricated by submerged-arc welding shops with ASME Section IX qualified procedures. Refractory-lined construction may be used where exhaust temperatures exceed 600 deg C continuous.
Worker comfort cooling — beyond compliance
Glass plant HVAC has historically been built to the bare minimum required for compliance. Modern Australian operators are upgrading worker comfort cooling because productivity, retention and absenteeism economics now favour better personnel HVAC.
Control room positive pressure
Plant control rooms — the central operations centre managing furnace combustion, gob distribution, IS machine timing, lehr profile and cold-end inspection — require positive pressure HVAC at 22-24 deg C, Class III filtration to F7 or better, 8-10 ACH. Hermetic door seals on the control room boundary maintain pressure. Filter pressure differential alarm warns when filters approach change-out. Redundant supply fans (N+1) ensure pressure is maintained on fan failure.
Operator pulpit refrigerated cooling
IS machine operator pulpits, hot-end inspection booths and any other operator station within 5 metres of furnace or IS machine radiant exposure require refrigerated supply air at 26-28 deg C through insulated supply duct (50 mm fibreglass insulation between inner and outer galvanised skins). Internal liner provides thermal break and prevents condensation on the inner duct surface — this matters because galvanised duct sweating in a hot ambient creates standing water that will corrode through the lower seam in 18-24 months.
Batch house dust-free operator zone
The batch house blending operator zone uses positive pressure HVAC with HEPA-grade filtration as the engineering control hierarchy upgrade — the operator works inside a Class III filtered booth with the dust-generating equipment outside. Pressure differential 12-25 Pa positive maintains dust-free conditions. Door interlocks prevent the operator from defeating the pressure regime.
Decoration and coating room HVAC
Decoration and coating is a separate department in most container plants and a significant HVAC fit-out scope. The processes — silk-screen printing, enamel coating, fluoropolymer coating, decoration bake-oven curing — generate VOC emissions that require dedicated capture and abatement.
Silk-screen printing booth
Silk-screen printing applies decorative inks to container surfaces through fine-mesh screens. Down-draft booth construction with galvanised SBAL-V plenum walls captures solvent vapour. Booth face velocity 0.4-0.5 m/s drives air past the operator into the down-draft plenum and out to a thermal oxidiser or activated carbon bed for VOC compliance.
Enamel coating bake oven
After silk-screen ink is applied, containers pass through a bake oven at 580-620 deg C for 10-20 minutes to fuse the enamel into the glass surface. Bake oven exhaust at 400-500 deg C uses 1.5 mm welded mild steel (outside SBKJ machinery scope) discharging through a thermal oxidiser for VOC abatement.
Decoration room ventilation
The decoration room itself requires general ventilation at 6-10 ACH with 22-24 deg C ambient and Class III filtration. Galvanised SBAL-V supply and SBTF spiral return throughout.
SBKJ machinery scope for glass plant HVAC duct fabrication
This is where the abstract HVAC engineering meets the concrete machinery procurement decision. A mechanical services contractor building dedicated duct fabrication capacity to serve Australian glass plant projects needs three classes of SBKJ machinery.
SBAL-V auto duct line — the workhorse
The SBAL-V auto duct production line handles 0.5-1.5 mm galvanised AND 304L stainless on a single dual-mode line, producing rectangular duct from 200x100 mm to 1500x1500 mm with Pittsburgh seam, TDF flange forming, beading and notching in one pass. Single-shift output 250-400 lineal metres per shift on standard configuration. Coil width capacity 1250 or 1500 mm matches AS/NZS 4254.2 standard duct sizes.
What SBAL-V covers in a glass plant: control room HVAC, batch house personnel zone, IS machine operator pulpit supply, lehr corridor HVAC, cold-end inspection room, decoration room ventilation, packaging area HVAC, electrical rooms, admin and laboratory zones. Approximately 65 percent of total HVAC duct length in a typical container plant. SBAL-V also produces 304L stainless duct for cold-end stearate coating exhaust, IS machine swabbing oil mist exhaust, float bath proximity returns and fibreglass binder oven exhaust — covering another 20 percent of duct length.
SBTF spiral tubeformer — return air mains
The SBTF spiral tubeformer winds round spiral pipe from 80-1500 mm diameter in galvanised and 80-1250 mm in stainless. Cut-to-length offline. Round spiral pipe is the most material-efficient construction for return air mains at long lengths — 30-40 percent less material per unit pressure drop than equivalent rectangular construction.
SBTF scope in a glass plant: return air mains for control room, batch house personnel zone, lehr corridor, cold-end inspection, decoration room. Operator pulpit supply runs where the corridor permits round duct (typically the longer horizontal runs above 8 metres). Approximately 12 percent of total HVAC duct length.
SBKJ duct welding line — pressure class D-E and stainless seam welding
The SBKJ duct welding machines handle longitudinal seam welding at 0.6-1.6 mm material, satisfying pressure class D-E (above 2500 Pa) and any leak-class A air-tightness requirement on stainless. Welding required for cold-end coating exhaust mains where leak-class A is specified, fibreglass binder oven exhaust where formaldehyde must not migrate, and any high-pressure batch-house collection main where Pittsburgh-seam class C is below specification. Approximately 3 percent of total duct length but disproportionately high value because welded leak-class A construction is the highest pressure-class and air-tightness output the SBKJ machinery range produces.
Outside SBKJ machinery scope
Three categories sit outside SBKJ standard machinery scope and require engagement of specialist welded-fabrication shops. First, high-temperature furnace exhaust (350-450 deg C regenerator stack, 1.5-3.0 mm welded mild steel or refractory-lined plate). Second, lehr stack exhaust (200-300 deg C, 1.5-2.0 mm welded construction). Third, decoration room bake oven exhaust (400-500 deg C, 1.5 mm welded mild steel). Approximately 5 percent of total HVAC-related duct length but a critical scope item that requires separate procurement.
The SBKJ engineering team helps customers plan this scope split at the quotation stage — itemising which lineal metres of the project go onto the SBAL-V, SBTF and welding line, and which go to subcontracted welded fabrication. Knowing this split before signing the project contract avoids the common procurement error of buying an SBKJ line for 100 percent of the project then discovering at fit-out that 5 percent has to be subcontracted at a premium.
Project lead time and delivery to Australian glass plants
Glass plant retrofits run on shutdown windows. Major shutdowns (4-6 weeks for furnace rebuild) recur every 8-12 years per furnace; minor shutdowns (1-2 weeks) recur annually. HVAC fit-out projects are scheduled into shutdown windows and lead time discipline is critical.
SBKJ machinery lead times
Standard SBAL-V auto duct line: 60-90 days from 30 percent T/T deposit to ex-works ready, plus 25-35 days ocean freight to Adelaide, Brisbane, Melbourne or Sydney. SBTF spiral tubeformer: 45-60 days plus shipping. SBKJ duct welding machine for stainless seam welding: 75-90 days plus shipping. Total project window from PO to commissioning is typically 16-22 weeks for a complete duct fabrication shop dedicated to a glass plant retrofit.
Coordination with shutdown windows
Visy Glass, O-I Australia and Saint-Gobain insulation contractors typically order SBKJ machinery 6 months ahead of plant shutdown windows, allowing 16-22 weeks for machine delivery and commissioning plus 4-8 weeks of duct prefabrication before the shutdown begins. Duct is prefabricated in the contractor's shop, packaged, and trucked to the plant for installation during the shutdown clear-out and rebuild phase.
Australian shipping ports
SBKJ machinery routinely ships to Adelaide (for O-I Glanville), Brisbane (for O-I Yatala), Melbourne (general) and Sydney (for O-I Penrith, Knauf Smithfield, Bradford Wagga via inland trucking, Saint-Gobain Australia distribution). Standard 40-foot high-cube container, ISPM-15 fumigated crating, full marine all-risk insurance. Inland trucking from port to contractor's shop arranged on either CIP destination or on customer-arranged inland transport.
How SBKJ supports glass plant HVAC duct fabricators
The SBKJ Engineering Team has supplied SBAL-V and SBTF machinery into mechanical services contractors building duct fabrication capacity for Australian glass plant projects since the 1990s. The standard support package covers six items:
- Pre-quotation engineering review. SBKJ engineers review the contractor's project brief and recommend the SBAL-V coil specification, SBTF diameter range and welding line capability matched to the duct fabrication scope. Itemised by lineal metres per pressure class and material.
- FAT against glass plant duct samples. Factory Acceptance Test before shipment runs the contractor's nominated coil through a full production cycle on the SBAL-V, including stainless mode and galvanised mode, with tolerance verification against AS/NZS 4254.2 pressure class C requirements.
- Installation supervision in Australia. 1-2 SBKJ engineers on site at the contractor's shop for 5-10 days for installation, mechanical commissioning and electrical commissioning, working with a multilingual technical translator if required.
- Operator and maintenance training. 8-16 hours operator training and 4-8 hours maintenance training in English, with a written commissioning report. Training covers stainless mode changeover procedure, tooling regrind schedule and PLC backup procedure.
- Spare parts continuity. One-year wear-parts kit shipped with the machine. Documented spare parts lead time under 14 days for stocked items, under 45 days for build-to-order. SBKJ continuity guarantee for spare parts on every machine model for 10+ years.
- Australian after-sales coverage. SBKJ Group's Australian operations at Box Hill North VIC provide English-speaking after-sales support, parts despatch and on-site service for Australian customers.
Get an itemised SBKJ quote for your glass plant duct fabrication project →
Glass plant HVAC vs other heavy industrial HVAC
For HVAC duct fabricators serving multiple heavy-industry sectors, glass-plant HVAC sits at the intermediate complexity tier. Three cross-sector comparisons matter.
vs steel mill / smelter HVAC
Steel mill HVAC handles higher process temperatures (steel BOF and EAF tap temperatures at 1650-1700 deg C) but lower silica RCS exposure than glass plant. Steel mill HVAC duct uses more 1.5-3.0 mm welded mild steel due to slag exposure, with less SBAL-V scope overall. See the steel mill and smelter HVAC duct guide for the full comparison.
vs cement plant HVAC
Cement plant HVAC handles much higher dust loadings than glass plant (cement raw mill and clinker cooler dust collection volumes are 3-5x glass batch house levels), with similar high-temperature ranges on the kiln preheater stack. The cement industry uses a higher percentage of welded fabrication and a lower percentage of SBAL-V galvanised. See the cement plant HVAC duct guide.
vs composite manufacturing HVAC
Composite manufacturing HVAC handles lower process temperatures than glass plant but more demanding chemical exhaust (epoxy resin volatiles, isocyanate emissions from polyurethane work, styrene from polyester resin). Stainless and FRP scope is proportionally higher. See the composite manufacturing HVAC duct guide for the full chemistry breakdown.
vs mining ventilation HVAC
Mining ventilation runs the largest duct cross-sections of any industrial HVAC application (3-5 metre diameter mainline mine ventilation duct is common) but at low pressure class and with simple galvanised material specification. SBTF spiral tubeformer at 1500 mm diameter is the standard fabrication route. See the mining ventilation HVAC duct guide.
Galvanised vs stainless — when to specify which
The single most common materials question on a glass-plant HVAC project is when to upgrade from galvanised to 304L stainless. The decision matrix is straightforward.
- Galvanised G90 (Z275) for: control room HVAC, batch house personnel zone, lehr corridor HVAC, cold-end inspection room, decoration room ventilation, packaging area HVAC, electrical rooms, admin and laboratory zones, dry batch house source-capture mains.
- 304L stainless for: cold-end stearate coating exhaust, IS machine swabbing oil mist, float bath proximity (within 5 m of bath roof), fibreglass binder oven exhaust, fibreglass cure oven exhaust, container glass hot-end coating exhaust, optical glass cleanroom returns, ion-exchange room (consider 316L for chloride resistance).
- Mild steel welded (outside SBKJ scope) for: high-temperature furnace exhaust, lehr stack exhaust, decoration room bake oven exhaust.
For a deeper material comparison, see the galvanised vs stainless steel duct guide.
Common procurement mistakes on glass plant HVAC projects
SBKJ engineers see the same handful of procurement mistakes repeatedly on glass plant HVAC retrofits. Avoiding them takes one Friday afternoon of upfront engineering review.
Mistake 1 — Buying a single-mode SBAL-V
Specifying an SBAL-V configured for galvanised only forces all stainless work onto subcontracted fabrication or a second machine. Glass plants need 20 percent or more of their duct in 304L stainless (cold-end coating, swabbing exhaust, binder oven exhaust). A dual-mode SBAL-V handles galvanised AND stainless on the same line with a 30-minute changeover — the incremental cost of dual mode at order time is recovered on the first stainless project.
Mistake 2 — Underestimating the scope split
Procuring SBKJ machinery for 100 percent of project duct then discovering at fit-out that 5-7 percent (the high-temperature furnace and lehr stack work) has to be subcontracted at a premium. The scope split should be in the quotation, not discovered on site.
Mistake 3 — Skipping the FAT
Skipping the Factory Acceptance Test on the assumption that "stainless is stainless" misses the chance to verify the contractor's specific coil performs cleanly through the SBAL-V Pittsburgh-seam tooling. The FAT is mandatory on every SBKJ auto duct line and should never be waived.
Mistake 4 — Wrong duct gauge for batch house mains
Specifying 0.7 mm galvanised on batch house source-capture mains because that is the standard HVAC office-building gauge. Silica-loaded airstreams abrade through 0.7 mm in 3-5 years; the correct specification is 1.0-1.2 mm galvanised, well within SBAL-V capability.
Mistake 5 — Galvanised on cold-end coating exhaust
Saving 30 percent material cost by specifying galvanised on the cold-end stearate coating exhaust. Galvanised corrodes through in 12-18 months from organic-acid breakdown of stearate residues. 304L stainless is the only economic choice.
Mistake 6 — No allowance for pressure class C in batch house
Designing the batch house dust collection main at pressure class B because pressure class C duct construction "costs more". The 1500-2000 Pa loading on a baghouse main flexes class B duct over a few weeks of pulse-jet cycling and unseats every Pittsburgh seam. Pressure class C is mandatory; SBAL-V output meets class C as standard.
Mistake 7 — Forgetting NFPA 654 on cullet processing
Treating cullet processing dust collection as identical to virgin batch dust collection. Cullet contains organic residue (label paper, plastic, food residue) and falls within NFPA 654 combustible dust scope. Explosion vents, isolation valves and electrostatic grounding are mandatory and easily forgotten at design stage.
FAQ
What is the major occupational health hazard in glass plant HVAC design?
Respirable crystalline silica (RCS). The OSHA PEL is 0.05 mg/m3 8-hour TWA, ACGIH TLV 0.025 mg/m3 8-hour TWA, Safe Work Australia workplace exposure standard 0.05 mg/m3. Engineering control hierarchy (substitution, isolation, local exhaust ventilation, then PPE) governs design.
What HVAC ductwork is within SBKJ machinery scope and what is outside?
SBKJ duct machinery handles 0.5-1.5 mm galvanised and 304L stainless on the SBAL-V, 80-1500 mm spiral pipe on the SBTF, and 0.6-1.6 mm welded seam on the duct welding line. High-temperature furnace exhaust (350-450 deg C, 1.5-3.0 mm welded mild steel or refractory-lined) is outside scope and requires welded-fabrication shops with ASME Section IX qualified procedures.
Can SBKJ machinery form 304L stainless duct?
Yes. SBAL-V forms 304L stainless from 0.6-1.5 mm with 30-minute changeover from galvanised mode. SBTF winds 304L spiral pipe up to 1.5 mm at 1500 mm diameter. Cold-end coating exhaust, IS machine swabbing oil mist and binder oven exhaust are all within SBKJ machinery scope at 304L.
What is the typical lead time for SBKJ machinery for a glass plant project?
SBAL-V auto duct line 60-90 days plus 25-35 days ocean freight to Australia. SBTF spiral tubeformer 45-60 days plus shipping. SBKJ duct welding machine 75-90 days plus shipping. Total 16-22 weeks from PO to commissioning. Order 6 months ahead of plant shutdown windows.
How does AS 1668.2 apply to glass plant HVAC?
AS 1668.2-2024 Section 5 covers general exhaust ventilation (personnel zones), Section 6 covers specific exhaust applications (batch house dust, cold-end VOC capture, IS machine swabbing oil mist). Pressure class C (up to 2500 Pa) is typical for batch house exhaust mains, class A-B for personnel comfort runs. SBAL-V output meets AS/NZS 4254.2 pressure class C as standard.
Which Australian glass operators specify HVAC duct retrofits?
O-I Australia (Visy Glass Recycling) at Adelaide, Brisbane and Sydney plants. Saint-Gobain Australia (gypsum and insulation through CSR/Boral). Bradford Insulation at Wagga Wagga. Knauf Insulation Australia at Smithfield NSW. Owens Corning Australia. Mechanical services contractors typically tender duct fabrication and run an SBAL-V or equivalent in-house.
What materials are specified for batch house HVAC duct?
Galvanised G90 (Z275) for personnel-zone supply and return. Heavier galvanised (1.0-1.2 mm) for source-capture local exhaust mains where silica abrasion is the wear mechanism. Hood transitions in 1.0-1.2 mm galvanised, mains in 0.7-1.0 mm galvanised, all SBAL-V scope. Pressure class C on dust mains, class A-B on personnel runs.
How do I size HVAC for the IS machine area in a container glass plant?
Operator pulpit at 26-28 deg C through 8-12 ACH refrigerated supply via insulated SBAL-V galvanised duct. Local exhaust over each section's swabbing station at 1.0-1.5 m/s face velocity into 304L stainless duct (SBAL-V scope) discharging through a mist eliminator and roof stack. Total duct length 300-500 lineal metres for a 10-section IS machine line.
