Float Glass, Mirror, Laminate, Tempered & IGU Manufacturing HVAC Duct Guide — Viridian, G.James, AGG, Carlite, Lite Wall

Why flat-glass HVAC is its own engineering discipline

A flat-glass manufacturing site is a hybrid plant. One end of the building is a thermal monster — the float bath holds molten tin at 1100 degrees Celsius under a hydrogen-bearing atmosphere, the regenerative melt furnace next door peaks at 1550 degrees, the annealing lehr walks the ribbon down from 600 degrees over the better part of an hour, and the tempering furnace later in the value chain heats finished lites back up to 620 degrees before slamming them with quench air. The other end of the building is a precision chemistry plant — silver nitrate cascaded onto mirror substrates, hydrofluoric acid etching frosted decorative glass, magnetron sputter coating laying down nanometre-thick low-emissivity stacks under vacuum at ten-to-the-minus-six millibar, argon and krypton inert gas fills sealed inside double-glazed insulating units. Between the two ends sits the architectural processing floor where 6 mm float lites get scored, broken, edge-ground, washed, tempered, laminated, IGU-assembled, framed and shipped to building sites from Perth to Cairns.

Each of those processes generates a dedicated airstream that has to be captured, conveyed and treated without contaminating the rest of the plant. Get the duct material wrong in the silvering department and you have galvanised duct corroding through inside three months from ammonia and alkali attack. Get the hazardous-area zoning wrong at the tin bath and you have an ignition risk inside an envelope holding hydrogen above its lower explosive limit. Get the HF etching extract material wrong and the fluoride eats through your duct in a season. Get the IGU assembly area pressure wrong and lint from the loading bay seeds the butyl seal interface and your insulating glass units fog inside the first year.

This guide is the complete engineering walk-through SBKJ runs with the mechanical services contractors building duct fabrication capacity for Australian flat-glass plants. It covers the five production families — primary float manufacturing, mirror silvering, automotive and architectural laminating, IGU and LowE coating, tempered safety glass — and the cross-cutting topics that touch every one of them: hazardous-area zoning under AS/NZS 60079, materials selection from galvanised through 316L stainless to FRP, the Safe Work Australia workplace exposure standard stack, NFPA 660 combustible dust review, and where SBKJ standard machinery scope ends and welded heavy-gauge fabrication begins.

The five production families on Australian sites

Australian flat-glass production splits into five process families that share some equipment and some staff but each present a distinct HVAC duct loading profile. A single site may run one family or several — Viridian's Dandenong plant runs float, tempering and laminating, G.James runs everything except primary float, AGG runs everything below primary float, Lite Wall focuses on IGU. The scope of HVAC work depends on which families are present.

Family 1 — Primary float glass manufacturing

Australia has one operating float-glass primary manufacturer: Viridian Glass, the CSR and Saint-Gobain joint-venture company running its float line at Dandenong VIC plus secondary processing at Ingleburn NSW and Erskine Park NSW. Pilkington Australia (NSG Group), AGC Asia Pacific (formerly Asahi), Guardian Industries and Cardinal CG distribute imported float into Australia from regional manufacturing sites but do not produce float domestically. The Viridian Dandenong float line is the only place in Australia where the full primary process runs — batch house, melt furnace, tin bath, annealing lehr, on-line CVD hard-coat coating (where specified), cut-down, and warehouse — and the only place in Australia where the full primary HVAC duct scope applies including tin-bath hazardous-area zoning and regenerator stack flue gas treatment.

The HVAC profile of a float line is dominated by the tin-bath hydrogen atmosphere (Zone 1 hazardous area to AS/NZS 60079.10.1), the regenerator stack flue gas at 350 to 450 degrees Celsius, the long annealing lehr corridor (60 to 100 metres of lehr length), and the batch house silica dust collection. Total HVAC duct length for a complete float line including all personnel zones, dust collection and process extract typically runs 800 to 1500 lineal metres of mixed rectangular and round construction across galvanised, 304L and 316L stainless and selected welded fabrication.

Family 2 — Architectural processing (cutting, edging, tempering, laminating, IGU)

Architectural processing is the much larger Australian sector by volume of HVAC scope, because every Australian state has multiple processors converting imported and Viridian-supplied float into finished architectural glass for the building industry. G.James Glass and Aluminium (Brisbane HQ plus sites in every state) is Australia's largest architectural processor; Australian Glass Group AGG (Dandenong VIC) is the largest Australian-owned independent processor; Capral Aluminium (Bremer Park QLD and Erskine Park NSW) is the largest aluminium frame plus glass integrator; Stegbar (JELD-WEN), Bradnam's, Wideline and Trend are major window and sliding-door fabricators; Lite Wall (Tullamarine VIC), Allglass (NSW), Vetro Glass (VIC), Total Glass (NSW), Glascorp (Sydney) and Apex Glass (NSW) round out the IGU and specialty architectural processor sector.

The HVAC profile of an architectural processor is dominated by tempering furnace heat extract, laminating autoclave room ambient, IGU assembly clean area positive pressure, edge grinding wet-process mist capture, and general cutting hall ventilation. Most architectural processors do not run silvering, HF etching or sputter coating in-house; those operations sit at specialist sites covered in the next three families below.

Family 3 — Mirror silvering

Mirror production in Australia is concentrated at a handful of specialist sites — Mirror Mate (Sydney custom mirror) being the largest dedicated specialist, with G.James and several smaller processors running short silvering lines for their own product. The silvering line is a wet chemistry process where silver nitrate solution is reduced to metallic silver on the freshly cleaned glass surface, then protected by a copper backing layer (electroless or sprayed) and a paint backing.

The HVAC profile of a silvering line is dominated by corrosive alkaline mist capture (silver nitrate plus ammonia plus sodium hydroxide plus reducer), copper backing extract, and mirror backing paint room VOC capture. 316L stainless duct mandatory throughout the silvering and copper backing extracts. Total HVAC duct length per silvering line typically 150 to 300 lineal metres of mostly 316L stainless plus paint room scope in 304L and galvanised.

Family 4 — Automotive glass laminating and tempering

Automotive glass production in Australia is concentrated at Carlite (CSR brand) at Dandenong VIC for windscreens and side glass, with O'Brien Glass (Belron), Novus Auto Glass and Smith & Smith running replacement-windscreen workshops and small-volume re-fabrication across the network. Automotive laminating uses a PVB (polyvinyl butyral) interlayer between two curved glass plies bent and pressed in a shaping oven, then autoclaved for the final cure. Tempered side and rear glass is heated to 620 degrees Celsius in a roller hearth furnace and quenched.

The HVAC profile of an automotive glass plant mirrors the architectural processor with two additions: the bending oven adds significant heat extract above the bend tool nest (304L stainless duct, SBAL-V scope), and the windscreen wash line (cascaded fresh-water rinse) adds humidity load on the cutting hall return air. Total HVAC duct length per automotive line typically 400 to 800 lineal metres.

Family 5 — Soft-coat LowE sputter and specialty

Soft-coat LowE (magnetron sputter vacuum deposition, MSVD) and specialty coatings such as anti-reflective, anti-glare and selective solar control sit in dedicated buildings at a handful of Australian sites. Viridian Glass runs MSVD at Ingleburn NSW; AGG runs MSVD at Dandenong VIC. The sputter line is a horizontal vacuum chamber with multiple cathode targets (silver, niobium, tin, zinc oxide) operating at ten-to-the-minus-six millibar with argon plasma. Glass lites pass through entry and exit airlocks.

The HVAC profile of an MSVD coater is dominated by clean-room-style HVAC for the loading and unloading robot area (Class III filtered, slight positive pressure), dedicated extract from the wet wash line that runs immediately before the sputter chamber, and amenity HVAC for the operator. The vacuum chamber itself and the turbomolecular pump manifold are welded vacuum vessels outside SBKJ scope. Specialty HF etching for decorative architectural glass overlaps with this family at selected sites and is covered separately in this guide because of the unique fluoride scrubber requirement.

The regulatory stack — what each Australian Standard governs

Flat-glass HVAC sits at the intersection of more Australian Standards than almost any other industrial sector, because it spans general mechanical ventilation, hazardous area classification, ductwork construction, fire-rated penetrations, safety glass production specifications, IGU assembly methodology, and a stack of workplace exposure standards on specific chemical agents.

AS 1668.2-2024 — mechanical ventilation in buildings

AS 1668.2 The use of mechanical ventilation and air-conditioning in buildings is the master Australian standard for personnel-occupied building HVAC. Section 5 covers general exhaust ventilation, Section 6 covers specific exhaust applications (manufacturing processes, paint spray booths, semiconductor fabrication, laboratory fume cupboards, kitchen exhaust). Most HVAC ductwork in an Australian flat-glass plant is governed by Section 5 (personnel zones, cutting halls, IGU assembly, control rooms) and Section 6 (silvering line corrosive mist, HF etching extract, mirror backing paint room VOC). Pressure classes and air-tightness leakage requirements cross-reference AS 4254.

AS 4254 — ductwork construction

AS 4254 Ductwork for air-handling systems in buildings sets the construction requirements for sheet metal ductwork: pressure class A through E (up to 2500 Pa positive, lower negative limits), air-tightness leakage classes, reinforcement schedules, gauge selection, seam types. Part 1 covers flexible duct; Part 2 covers rigid duct. Pittsburgh seam construction satisfies pressure class A through C; longitudinal seam welding via the SBKJ SB-ZF1500 stitchwelder or SBLR-600 laser welder is required for class D-E and for any leak-class A air-tightness on stainless service. SBAL-V auto duct line output meets AS 4254.2 pressure class C up to 2500 Pa as standard on Pittsburgh seam.

AS 1530.4 — fire-rated penetrations

AS 1530.4 Methods for fire tests on building materials, components and structures Part 4 covers fire-resistance test methods for elements of construction. Duct penetrations through fire-rated walls and floors in a flat-glass plant — separating the silvering chemistry room from the cutting hall, separating the LPG store from the tempering hall, separating the office block from the production floor — require fire-rated dampers or fire-rated duct construction tested to AS 1530.4.

AS/NZS 60079 — hazardous areas

AS/NZS 60079 series Explosive atmospheres applies to several flat-glass plant locations: the tin-bath hydrogen envelope under AS/NZS 60079.10.1 gas zoning, the LPG-fired tempering furnace burner train, the natural-gas furnace combustion chamber, the silver nitrate decomposition zone (in the unlikely event of fire), the solvent storage room, and the combustible dust zones under AS/NZS 60079.10.2 plus NFPA 660 cross-reference for cullet, silica raw material handling, and any organic-residue contamination in recycled cullet. Each Zone 0, 1, 2, 20, 21 or 22 classification dictates duct bonding, spark-resistant fan selection (AMCA Type A or B), motor IP rating, light fitting Ex rating, instrument intrinsic safety, and isolation valve placement.

AS 1940 — flammable and combustible liquids

AS 1940 The storage and handling of flammable and combustible liquids governs solvent storage and handling: IPA (isopropyl alcohol), MEK (methyl ethyl ketone), toluene, xylene used as cleaning solvents on the laminating line and as carrier solvents in mirror backing paint; formaldehyde solution used as the silvering reducer; PVB film handling areas. Storage rooms require dedicated ventilation, bunded floors, fire-rated separation and segregation by dangerous-goods class.

AS 4332 and AS 1604 — gases

AS 4332 The storage and handling of gases in cylinders and AS 1604 Specification for preservative treatment apply to the compressed gas cylinders used across the flat-glass plant: argon and krypton for IGU fill, nitrogen for the float bath atmosphere, hydrogen for the float bath atmosphere (typically piped from a hydrogen generator or supplied in pressurised tube trailer), oxygen-fuel mixtures for any cutting torch operations, and compressed air for the tempering quench and pneumatic conveyor power.

AS 2047 and AS 1288 — windows and architectural glazing

AS 2047 Windows and external glazed doors in buildings and AS 1288 Glass in buildings — Selection and installation are the product standards governing the architectural glass produced by Australian processors. They do not govern HVAC duct directly but they govern the production quality control regime that drives QC laboratory HVAC requirements (climate controlled, plus or minus 1 degree Celsius and plus or minus 5 percent relative humidity stability).

AS/NZS 4666 — IGU insulating glass units

AS/NZS 4666 Insulating glass units governs the assembly methodology for sealed double-glazed and triple-glazed insulating glass units: spacer bar materials and warm-edge technology, primary butyl seal application, secondary polysulphide or silicone seal application, argon and krypton fill methodology, leak testing and warranty performance. The standard drives the IGU assembly area HVAC requirement: positive pressure (plus 10 to 15 Pa) to keep dust and lint out of the seal interface, low particulate supply air, climate stability for consistent seal cure.

AS/NZS 2208 and AS/NZS 4667 — safety glass

AS/NZS 2208 Safety glazing materials in buildings and AS/NZS 4667 Quality requirements for cut-to-size and processed glass govern tempered (toughened) and laminated safety glass production. Tempered glass shall break into small relatively harmless pieces (the standard fragmentation test) when broken; laminated glass shall hold fragments to the interlayer when broken (the impact test). Production quality control for AS/NZS 2208 compliance drives heat-soak test oven requirements (290 degrees Celsius for 2 to 4 hours per EN 14179 protocol, detecting nickel sulphide inclusions that would otherwise cause spontaneous breakage in service) and laminating autoclave cycle compliance.

AS 1428 — disability access

AS 1428 Design for access and mobility sets the disability and accessibility requirements for the building envelope, including any HVAC controls and emergency egress that staff with limited mobility might need to access during a plant emergency.

NFPA 86 — industrial furnaces

NFPA 86 Standard for Ovens and Furnaces governs combustion safety and exhaust design for fuel-fired industrial furnaces. The float-glass melt furnace, the on-line CVD chamber if gas-fired, the tempering furnace, the laminating autoclave, the heat-soak oven, the bent and slumped glass kilns, and the mirror backing paint cure oven all fall within NFPA 86 scope. Australian operators typically follow AS 4041 piping code and AS 1228 boiler code in parallel for combustion-related piping. NFPA 86 Chapter 8 governs furnace exhaust design.

NFPA 660 — combustible dust

NFPA 660 (the 2025 consolidated standard that replaced and merged NFPA 484 metals, NFPA 654 particulate solids, NFPA 655 sulphur, NFPA 664 wood and NFPA 61 agricultural) governs combustible-dust deflagration risk. Pure silica sand, soda ash and limestone batch materials are non-combustible and exempt. Cullet processing zones with organic contamination from labels, plastic closures or food residue fall within scope at dust layer thickness above 0.4 mm. Silver-nitrate handling dust is mildly combustible under fire conditions and is reviewed under NFPA 660 by most insurance carriers. Glass dust from cutting and grinding is non-combustible. Required engineering controls include explosion vents on baghouse hoppers (sized per NFPA 68), isolation valves between dust collectors and process equipment, electrostatic grounding on all duct and equipment, and dust-tight construction on duct seams.

ASHRAE Applications Handbook Chapter 35 — industrial drying and heating

ASHRAE Applications Handbook Chapter 35 Industrial Drying and Heating provides design intent for industrial heat-load HVAC: lehr corridor design, tempering furnace heat extract, laminating autoclave room ambient, bent and slumped glass kiln corridor. ASHRAE is a reference rather than a binding standard in the Australian regulatory environment, but it is the practical design source most Australian consultants use alongside AS 1668.2.

Industry references — IGCC, WGMA, AGGA, AWA

The Insulating Glass Certification Council (IGCC, US reference) and the Window and Glass Mirror Association (WGMA, US reference) provide product certification and best-practice guidance widely referenced in Australian practice. Domestically, the Australian Glass and Glazing Association (AGGA), the Australian Window Association (AWA), the Glass and Window Association NSW (GWANSW), the Glass Association of Australia (GAA), the Window and Door Manufacturers Association of Australia and New Zealand (WMAANZ) and the Insulating Glass Manufacturers Association (IGMA) publish member technical bulletins that are routinely cited in Australian project specifications.

Safe Work Australia workplace exposure standards — the WES stack

Safe Work Australia publishes workplace exposure standards (WES) for airborne chemical and physical agents under the model Work Health and Safety regulations. The flat-glass plant WES stack is one of the densest in any manufacturing sector. HVAC duct sizing, hood capture velocity and extract treatment train selection all derive from holding personal exposure below these limits.

Hydrogen: 25 percent of the lower explosive limit (LEL) is the engineering control alarm threshold inside the float-bath hazardous-area envelope, with continuous monitoring. Carbon monoxide: 30 ppm 8-hour TWA, relevant near the regenerative furnace exhaust and any combustion incomplete-burn condition. Nitrogen dioxide: 5 ppm short-term exposure limit (STEL), relevant near combustion exhausts. Sulphur dioxide: 2 ppm WES, relevant near the float bath sulphur outgassing scrubber and any heavy-fuel-oil combustion. Fluoride: 2.5 mg per cubic metre 8-hour TWA, the controlling limit for the HF etching department.

Silver nitrate has no formal Safe Work Australia WES but is a skin and respiratory irritant requiring engineering control to a practical low level — typically 0.01 mg per cubic metre at the operator station as a working design target. Formaldehyde: 1 ppm STEL, relevant in the silvering reducer system and in the mirror backing paint room. Ammonia: 25 ppm 8-hour TWA, relevant in the silvering line and in any chemistry-room storage. Tin oxide is related to the float-bath atmosphere and is controlled to general particulate WES limits (10 mg per cubic metre inhalable, 3 mg per cubic metre respirable).

Respirable inhalable dust: 10 mg per cubic metre 8-hour TWA, the general particulate limit applicable to glass cullet and raw material handling. Respirable crystalline silica: 0.05 mg per cubic metre 8-hour TWA under the 2024 Safe Work Australia regulatory update — the controlling limit for batch house, edge grinding and any cutting operation on glass containing crystalline silica.

Solvent stack for the laminating, mirror backing paint and cleaning operations: MEK 200 ppm 8-hour TWA, IPA 400 ppm 8-hour TWA, toluene 50 ppm 8-hour TWA, xylene 50 ppm 8-hour TWA. Each requires source-capture LEV at the workstation conveying to either thermal oxidation, activated carbon adsorption or wet scrubber depending on the loading and discharge licence.

Batch house and tank end — the silica problem

The batch house and tank end of a primary float line is the highest-RCS-exposure zone in any flat-glass plant. Engineering control hierarchy applied to the batch house translates directly into duct design and is the same approach used by Australian container-glass plants — see the container and fibreglass glass manufacturing HVAC duct guide for the parallel scope.

Raw materials and silica RCS

The float-glass batch is approximately 72 percent silica sand, 14 percent soda ash, 10 percent limestone and dolomite, 4 percent assorted minor ingredients (feldspar, salt cake, iron oxide colourants where required, selenium for clear glass decolourisation). Cullet is reintroduced at 20 to 40 percent depending on furnace capability. Every transfer point — bag dump, hopper inlet and outlet, mixer charging port, mixer discharge chute, conveyor head and tail pulley transfer, pneumatic conveying receiver, batch bin vent — generates a dust plume. Silica sand is the dominant respirable crystalline silica source.

Source-capture LEV design

Local exhaust hoods at every transfer point capture dust at the source. Capture velocity 1.5 to 2.5 metres per second per ACGIH Industrial Ventilation Manual, with hood design (lateral exhaust on bag dump, downdraft on weigh hopper, full enclosure on mixer) selected by the dust loading and operator access requirement. Trunk duct sized for 18 to 22 metres per second transport velocity to prevent silica drop-out. Hood transitions in 1.0 to 1.2 mm galvanised — heavier than standard HVAC galvanised because of abrasion from silica-loaded airstreams. Trunk duct standard 0.7 to 1.0 mm galvanised on Pittsburgh seam.

The SBKJ SBAL-V auto duct line handles 0.5 to 1.5 mm galvanised at coil width 1250 or 1500 mm at forming speed 16 metres per minute, covering the entire batch house source-capture range on a single line with no tooling change between gauges.

Baghouse and discharge

Pulse-jet baghouse with PTFE membrane media (W.L. Gore Gore-Tex bonded to a polyester substrate is the industry default) at 1.0 to 1.5 metres per minute air-to-cloth ratio is standard for silica service. PTFE membrane provides surface filtration and resists blinding by fine silica. Baghouse efficiency at the membrane is typically 99.99 percent removal at 0.5 micron, satisfying the 0.05 mg per cubic metre WES on the discharge stack with substantial margin.

Baghouse inlet duct 1.0 to 1.2 mm galvanised. Hopper isolation valve isolates the baghouse from upstream process during filter changeout. Explosion vent on the hopper roof per NFPA 660 (formerly NFPA 654) where cullet loading creates a deflagration risk. Bonded electrostatic earthing on every duct flange.

Cullet processing — NFPA 660 and lithium-ion contamination

Recycled cullet enters the batch house from the cullet receival yard. Visy Glass Recycling supplies most of the container glass cullet to Australian container plants; flat-glass plants typically use their own internal cut-off offcuts as primary cullet plus selectively imported flat cullet. Cullet contaminated with organic residue (label paper, plastic closures, food residue in container cullet) falls within NFPA 660 combustible-dust scope above 0.4 mm dust layer thickness.

The emerging concern is lithium-ion battery contamination of mixed cullet streams. Small consumer batteries (vape devices, hearing aids, button cells) inadvertently entering recycling streams alongside bottle and flat glass have caused multiple plant fires globally since 2022. Cullet processing zones now require fire detection (infrared spot detectors and continuous CO monitoring), automatic dampering to isolate the baghouse on fire signal, and explosion venting on the baghouse hopper per NFPA 660.

The melt furnace — what is and is not in scope

The float-glass melt furnace is the largest piece of process equipment at Viridian Glass Dandenong and the largest single source of NOx and SOx emissions at the site. The HVAC duct scope around the furnace splits cleanly into two categories.

Furnace process exhaust — outside SBKJ machinery scope

The regenerative melt furnace runs at 1500 to 1550 degrees Celsius melting temperature with combustion typically natural gas or heavy fuel oil (some plants are converting to oxy-fuel for emissions reduction). The flue gas exits the regenerator at 350 to 450 degrees Celsius after heat recovery, passing through a selective catalytic reduction (SCR) reactor for NOx control, then a wet scrubber or electrostatic precipitator for SOx and particulate, then the stack. The exhaust train is 1.5 to 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. Lifecycle is 15 to 20 years between major rebuilds.

This sits outside SBKJ machinery scope for three reasons. Material thickness: SBAL-V handles up to 1.5 mm and the SB-ZF1500 stitchwelder handles up to 1.6 mm; heavy-gauge furnace exhaust at 1.5 to 3.0 mm needs plate rolling and submerged-arc welding capability that sits in a different equipment class. Temperature: standard duct construction is rated to 80 degrees Celsius continuous, furnace exhaust at 350 to 450 degrees Celsius requires bellows expansion joints, refractory lining and fully welded construction. 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.

Furnace personnel zone HVAC — within SBKJ machinery scope

The ambient HVAC around the furnace is full SBKJ machinery scope. The hot-end operator pulpit (a control booth on the furnace charging end) needs filtered refrigerated supply air at 26 to 28 degrees Celsius through insulated galvanised SBAL-V supply duct. The electrical room serving the furnace combustion controls needs positive pressure HVAC at 22 to 24 degrees Celsius with Class III filtration. The maintenance corridor between the furnace wall and the tin bath needs general ventilation at 10 to 12 air changes per hour for personnel access during shift handover.

All of those runs are SBAL-V scope in galvanised with selective 304L stainless on returns within 3 metres of furnace wall radiant exposure due to heat ageing of zinc galvanising at sustained surface temperature above 80 degrees Celsius. Typical lengths 100 to 200 lineal metres of mixed rectangular and spiral construction per furnace serving zone.

Tin bath ventilation — the hydrogen Zone 1 hazardous area

The tin bath is the defining feature of float-glass production and presents HVAC challenges no other glass production family encounters. The bath is a long shallow tank of molten tin (typically 50 metres long, 10 metres wide, 50 to 150 mm deep tin layer) maintained under a reducing atmosphere of nitrogen plus 4 to 7 percent hydrogen to prevent tin oxidation. Molten glass at 1100 degrees Celsius floats on the tin surface and spreads to a uniform thickness; glass exits at 600 degrees Celsius onto the lehr. The hydrogen blanket is the controlling HVAC hazard.

Hazardous area classification to AS/NZS 60079.10.1

The bath roof penetrations (thermocouples, gas sample probes, top heater elements, visual inspection ports) and the seal mechanisms at glass entry and exit are classified Zone 1 (flammable gas likely present in normal operation) under AS/NZS 60079.10.1. The bath enclosure surrounding the bath itself is Zone 2 (flammable gas not likely in normal operation but if present will exist for short period only). The classification dossier is part of the plant fire engineering submission to the state regulator and is reviewed every 5 years.

Inside the Zone 1 and Zone 2 envelope, every electrical fitting, motor, light, instrument, junction box and cable gland is rated Ex e (increased safety), Ex d (flameproof), Ex n (non-sparking, suitable for Zone 2 only) or intrinsically safe Ex ia/ib. Fans inside the envelope are spark-resistant AMCA Type A (all-metal construction with no aluminium-on-steel rubbing surfaces) or Type B (aluminium on steel acceptable but with non-sparking liners). Motors are TEFC Ex e or Ex d to the appropriate temperature class T1 to T6 depending on the autoignition temperature of the gas being managed (hydrogen T1, 560 degrees Celsius).

Ductwork inside the zoned envelope

Every duct within the zoned envelope is bonded for electrostatic dissipation: continuous earth-bonding wire across every flange, every joint, every transition. Bonding resistance to earth measured at less than 10 ohms during commissioning and re-verified annually. Duct material 304L stainless or 316L stainless depending on tin oxide and sulphate condensation exposure — 304L within 5 metres of the bath roof penetrations, 316L where direct atmospheric leakage may carry chloride from any seal mechanism failure mode.

Hydrogen monitors at every fan inlet and every penetration alarm at 25 percent of LEL hydrogen (about 1 percent by volume in air). Alarm chain drives a sequence: silence audible at 25 percent LEL, full plant alarm at 40 percent LEL, ventilation exhaust ramp at 50 percent LEL, plant emergency shutdown at 60 percent LEL. Continuous hydrogen monitoring is required by the plant fire engineering case and is verified at quarterly intervals.

Bath enclosure ambient HVAC

Personnel access to the float bath is via a corridor running the bath length. Ambient HVAC targets 32 degrees Celsius maximum at occupied workstations through 8 to 10 air changes per hour. Supply air through insulated galvanised SBAL-V supply duct delivered at 4-metre intervals along the corridor (galvanised acceptable in the corridor because supply air is fresh outside air entering the enclosure, not return air from inside the enclosure). 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 stainless SBAL-V duct, conveying to a wet scrubber for sulphur outgassing capture (sulphur impurity in the tin slowly migrates to the bath surface and is liberated as hydrogen sulphide and sulphur dioxide). Scrubber housing 316L stainless fabricated on the SB-ZF1500 stitchwelder for leak-class A. The scrubber is the final defence against tin and sulphur emissions reaching the plant boundary.

Tin emissions licence

Float plant emissions licences typically include a tin emissions limit (10 to 50 micrograms per cubic metre at the boundary). The bath enclosure exhaust through the scrubber is the controlled pathway. Continuous emission monitoring (CEM) at the stack with quarterly accuracy test by an EPA-accredited laboratory verifies compliance. The CEM duct is typically 316L stainless SBAL-V scope.

Annealing lehr — the cooling corridor

The annealing lehr is a slow-cooling tunnel that walks the glass ribbon from 600 degrees Celsius at the bath exit down to approximately 100 degrees Celsius at the lehr outlet, over 60 to 100 minutes residence depending on glass thickness. Annealing relieves residual thermal stress, without which the float ribbon would self-shatter or could not be cut and processed downstream.

Lehr exhaust — outside SBKJ scope

Lehr exhaust gas at 200 to 300 degrees Celsius exits through a roof stack. Lehr stack construction is welded mild steel or 304L stainless at 1.5 to 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 scope

The lehr corridor — the walkway running parallel to the lehr exterior — needs personnel HVAC at 30 degrees Celsius maximum ambient through 6 to 8 air changes per hour. Lehr exterior wall surface temperature drops from approximately 60 degrees Celsius at the inlet end to 35 degrees Celsius at the outlet end. 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 SBSF-1525-flanged round spiral return main.

Total corridor HVAC duct length 80 to 200 lineal metres for a 60 to 100 metre lehr. All within SBAL-V machinery scope. The SBSF-1525 round-duct flanging machine forms the round flange transitions for the spiral return main, supplying galvanised and 304L round duct at diameters from 100 to 1525 mm.

On-line CVD hard-coat LowE — at the cold end of the bath

On-line CVD (chemical vapour deposition) hard-coat LowE coating is applied to the molten ribbon at the cold end of the tin bath, before the ribbon exits onto the lehr. The CVD chamber sits inside the bath enclosure, sharing the hazardous-area envelope. Coating precursor (typically a tin halide for the conductive layer plus selected fluorine-doped silicon precursors for the LowE stack) is sprayed onto the moving ribbon surface and pyrolytically decomposes at the ribbon temperature (approximately 600 degrees Celsius). Hard-coat is durable, withstands tempering and laminating, but offers lower performance than soft-coat sputter.

CVD chamber extract

The CVD chamber extract captures any over-spray precursor and any combustion products. Duct 316L stainless because precursor decomposition products include hydrogen halides (HCl, HF, HBr depending on precursor) — galvanised would fail in days, 304L is challenged. SBAL-V handles 316L on the same coil mode as 304L. Extract conveys to a wet scrubber with caustic recirculation, then through a demister and stack.

CVD chamber HVAC duct sits inside the hazardous area envelope and follows the same bonding, Ex-rating and spark-resistant fan requirement as the bath. Continuous monitoring at the scrubber outlet verifies removal efficiency on the precursor compound of interest.

Offline soft-coat MSVD sputter — clean HVAC and vacuum manifolds

Offline magnetron sputter vacuum deposition (MSVD) for soft-coat LowE coating is a fundamentally different process from on-line CVD. The sputter line is a horizontal vacuum chamber, typically 30 to 50 metres long, with multiple cathode targets (silver, niobium, zinc oxide, tin, titanium dioxide) operating in an argon plasma at ten-to-the-minus-six millibar pressure. Glass lites enter through a vacuum airlock, pass through the cathode chamber on a roller conveyor, and exit through a second airlock. Coating deposition is highly directional and nanometre-thin.

Sputter chamber and pump manifold — outside SBKJ scope

The vacuum chamber itself and the turbomolecular plus rotary backing pump manifolds are welded vacuum vessels — typically 316L stainless plate, welded by orbital TIG with helium leak detection on every weld pass, vacuum-rated flanges with copper or viton seals. Lifecycle is 20 to 30 years. This is welded-fabrication scope, executed by specialist vacuum vessel shops, not standard sheet metal duct machinery.

Sputter building HVAC — within SBKJ scope

The HVAC surrounding the sputter chamber is full SBKJ scope. The sputter building runs at Class III filtration (HEPA grade or better) with slight positive pressure to keep external dust out. Supply air through insulated galvanised SBAL-V duct, return through 304L stainless main (low-particulate construction with minimum exposed seams). Operator control room at Class III filtered positive pressure, 22 to 24 degrees Celsius. Loading and unloading robot bays at general ventilation 6 to 8 ACH.

Upstream of the sputter chamber, the glass wash line removes any dust, oil or fingerprint before sputter coating. Wash line ambient generates humidity; return air on horizontal runs within 3 metres of the wash line uses 304L stainless to resist condensate corrosion. Downstream of the sputter chamber, the coated lites stack on a packing line for despatch.

Argon supply and management

The sputter chamber is fed argon (the working gas for the plasma) from compressed cylinders or a bulk argon vessel. AS 4332 governs cylinder storage and AS 1604 covers compressed gas piping. Argon is inert and non-flammable but is heavier than air and can displace oxygen in low-lying areas, creating an asphyxiation hazard. Oxygen depletion monitors at floor level in the argon cylinder room and in any pit or trench in the sputter building alarm at 19.5 percent oxygen (below normal ambient 20.9 percent) and shut down the argon supply at 18 percent.

Cutting and washing lines — the architectural processor's front end

Every architectural processor in Australia starts with float lites delivered on transport racks from Viridian Glass Dandenong or imported via Pilkington Australia, AGC Asia Pacific, Guardian Industries or Cardinal CG distribution. The lites are cut to size, edge-ground, washed, and queued for tempering, laminating or IGU assembly.

CNC cutting tables

Float lites are scored on CNC scoring tables, then broken along the scored line on a breakout table. Cutting halls run minor extract (4 to 6 air changes per hour) with no significant dust loading because float glass cuts cleanly along the score line. Minor glass dust is captured at the CNC table edge through low-velocity exhaust slots feeding a small dust collector with HEPA-grade discharge. Galvanised SBAL-V scope throughout.

Edge grinding wet department

Edge grinding shapes the cut edge to the architectural specification — typically arrissed (slightly chamfered), pencil-edge, flat-polished or bevelled depending on the end use. Diamond grinding wheels remove glass at a controlled rate with cascaded recirculating water-glycol slurry to suppress dust and cool the wheel face. The Australian default is wet grinding precisely because dry grinding would generate respirable crystalline silica above the 0.05 mg per cubic metre WES.

Wet grinding still requires LEV at each grinder to capture the fine mist that escapes the slurry containment. Capture face velocity 1.0 to 1.5 metres per second through 304L stainless hood (alkaline slurry pH 9 to 11 from glass silicate dissolution; galvanised would corrode in months). Trunk duct 304L stainless SBAL-V scope to a centrifugal mist eliminator and discharge stack.

Washing line

The washing line is a cascaded fresh-water rinse running before tempering, laminating, IGU assembly or sputter coating. Cleanliness is critical — surfactant residue, fingerprint oil or dust under the next-step coating or seal layer creates a permanent defect. Washing line ambient generates significant humidity load (typically 60 to 70 percent relative humidity in the wash hall). Return air on horizontal runs within 3 metres of the wash line uses 304L stainless to resist condensate corrosion. Wash hall ambient general ventilation 8 to 10 ACH.

Tempering and toughening furnace HVAC

Tempering produces toughened safety glass to AS/NZS 2208 by heating cut and edge-ground float lites to approximately 620 degrees Celsius in a horizontal roller furnace, then quenching with high-pressure air jets to create the surface compression. Quenched glass exhibits the characteristic small-fragment breakage pattern when broken — required for safety glazing applications under AS 1288 and AS 2047.

Heat load and operator HVAC

The preheat tunnel and the quench discharge create intense heat load in the tempering hall. Ambient temperatures hit 38 to 45 degrees Celsius without active extract. Personnel HVAC targets 30 to 35 degrees Celsius maximum at occupied workstations through 12 to 18 air changes per hour over the tempering hall, delivered via 304L stainless extract duct above the line (SBAL-V scope at 1.0 to 1.5 mm — 304L preferred over galvanised because of sustained surface temperature near 80 degrees Celsius limit). Operator pulpit refrigerated supply air at 26 to 28 degrees Celsius through insulated galvanised SBAL-V supply duct.

Quench air management

The quench discharges hot air at 150 to 200 degrees Celsius downstream of the lites. The quench plenum itself is welded fabrication (sized for 15 to 20 bar working pressure at peak), not SBKJ scope. Quench exhaust above the line captures through 304L stainless duct at 1.0 to 1.5 mm SBAL-V scope, conveying to a roof discharge stack with no further treatment (the quench air is clean filtered ambient air being recirculated at temperature).

NFPA 86 cross-reference

NFPA 86 industrial furnace standard covers the combustion-safety design of the gas-fired tempering furnace itself: burner train, flame supervision, purge sequence, interlocks, exhaust stack. The combustion exhaust stack from the furnace burner train is welded fabrication (typically 304L stainless or aluminised carbon steel at 1.5 to 2.0 mm) and sits outside SBKJ standard machinery scope.

Heat-soak test oven

Tempered glass intended for structural facade applications (point-fixed glazing, all-glass facades, balustrades, AS 1288 critical applications) is heat-soak tested to EN 14179 protocol: held at 290 degrees Celsius for 2 to 4 hours to deliberately propagate any nickel sulphide (NiS) inclusions to failure during the test rather than in service. Heat-soak oven exhaust is minor heat extract via 304L stainless SBAL-V duct. NiS detonations during the soak test occasionally fragment the test lite — the oven design absorbs the energy, but the exhaust duct must withstand any escape pressure pulse without seam failure.

Laminating autoclave HVAC

Lamination assembles a polymer interlayer between two or more glass plies under heat and pressure, creating laminated safety glass to AS/NZS 2208. Three interlayer chemistries dominate Australian production: PVB (polyvinyl butyral) for general architectural and automotive, EVA (ethylene vinyl acetate) for specialty applications, and SGP (SentryGlas Plus, an ionomer) for structural applications where post-breakage glass retention is critical (balustrade, point-fixed, hurricane-resistant).

Pre-bonding cleaning

Prior to assembly, each glass ply is washed in cascaded fresh water and the interlayer is cleaned of any antiblock agent. The cleaning station may use IPA (isopropyl alcohol) or a proprietary detergent. IPA cleaning generates VOC at typical 200 to 400 ppm at the cleaning station, requiring source-capture LEV at 0.5 to 1.0 metres per second face velocity through 304L stainless hood (IPA is mildly hygroscopic in extract air and 304L resists the trace humidity). Trunk duct conveys to a carbon adsorption bed or a thermal oxidiser depending on the IPA loading and the state EPA licence.

Assembly room ambient

The laminating assembly room is the cleanest area in an architectural processor — typically held at Class III filtration with slight positive pressure to keep dust off the interlayer film. Climate stability matters: 22 to 24 degrees Celsius, 40 to 50 percent relative humidity. PVB is hygroscopic and absorbs moisture if held in high-humidity ambient for prolonged periods, causing edge defects in the cured laminate. Supply air through insulated galvanised SBAL-V duct, return through 304L stainless main.

Autoclave cycle

The assembled lites pass into the autoclave, which is pressurised to 14 bar with nitrogen and heated to 140 degrees Celsius for 2 to 4 hours. The autoclave is a pressure vessel and welded-fabrication scope, not SBKJ scope. Autoclave room ambient HVAC handles the radiant heat from the autoclave shell (typically 50 to 60 degrees Celsius outer surface) through general extract at 6 to 8 air changes per hour. Galvanised SBAL-V scope.

Solvent VOC and aldehyde monitoring

PVB film off-gases minor amounts of plasticiser and any residual butyric acid during the autoclave cycle. EVA off-gases minor acetic acid. SGP off-gases minor ionomer plasticiser. The off-gassing is contained within the autoclave during the cycle and vented at end-of-cycle through a small bleed line into a carbon polishing filter. The bleed line is 316L stainless because of the corrosive trace organic acids.

IGU assembly — the clean area

Insulating glass unit (IGU) assembly is the architectural processor's cleanest production zone outside the sputter building. IGU performance depends on a hermetic seal that holds for 25 to 40 years in service, retaining the argon or krypton inert gas fill that delivers the U-value performance. AS/NZS 4666 governs the assembly methodology and the IGCC and IGMA references provide the international best-practice baseline.

Spacer bar bending

The spacer bar (the inner perimeter element that holds the two lites apart) is either aluminium box section (traditional) or warm-edge polymer or stainless thermal-break (modern). TPS (Thermal Plastic Spacer) is an integral warm-edge system extruded onto the glass directly without a separate bar. Spacer bar bending machines form the corners of the bar to the IGU geometry. Aluminium spacer is bent cold with minor heat extract; TPS extrusion generates minor hot-melt vapour requiring 304L stainless source-capture LEV at the extrusion head.

Desiccant filling

The aluminium or stainless spacer bar is filled with molecular sieve desiccant (3A type) to absorb any residual moisture inside the IGU cavity. Desiccant filling is dusty — molecular sieve generates a fine alumino-silicate dust at the filling station. LEV at 0.8 to 1.2 metres per second face velocity through galvanised hood (SBAL-V scope) into a small baghouse dedicated to the desiccant filling station.

Butyl primary seal

Butyl primary seal (polyisobutylene) is extruded around the spacer perimeter from a heated barrel at 130 to 150 degrees Celsius. Butyl generates minor hot-melt vapour requiring source-capture LEV at the extrusion head (304L stainless hood and trunk, SBAL-V scope). The primary seal is the gas-tightness layer that retains the argon or krypton fill.

Secondary seal — polysulphide or silicone

After spacer bar assembly into the unit, the secondary seal — polysulphide (traditional) or silicone (modern, particularly for structural glazing applications) — is pumped into the perimeter gap between the spacer outer face and the glass edge. Polysulphide is a two-component system with significant mercaptan odour generating extract requirement around the mixing and pumping station. 304L stainless LEV hood at the pump head with trunk duct conveying to a carbon polishing filter. Silicone is one-component and generates much less odour, but small acetic acid off-gas requires similar 304L stainless extract.

Argon and krypton fill

The IGU is purged of air and filled with argon (typical, lower cost) or krypton (premium, higher performance) inert gas before the secondary seal is completed. Fill methodology is either two-hole flushing or one-hole vacuum-and-fill. Both methods require precision control of fill purity (typically 90 percent argon or krypton minimum at unit completion) and leak detection.

Argon and krypton are heavier than air and can displace oxygen in low-lying areas. Oxygen depletion monitors at floor level in the fill station and in any pit or trench alarm at 19.5 percent oxygen. AS 4332 cylinder storage and AS 1604 piping governance apply to the argon and krypton supply system.

Cure oven

After the secondary seal is applied, IGUs pass through a cure oven at 80 degrees Celsius for 30 to 60 minutes to accelerate polysulphide or silicone cure. Cure oven exhaust is minor heat extract at 304L stainless SBAL-V scope, with carbon polishing filter on any solvent breakthrough.

Clean area positive pressure

The IGU assembly area runs at positive pressure (plus 10 to 15 Pa relative to corridors) to keep external dust and lint out of the butyl extrusion path. A single dust particle entrained in the primary seal interface creates a permanent capillary leak path that fails the IGU within 5 to 10 years of service. Class III filtered supply air at 8 to 10 air changes per hour through insulated galvanised SBAL-V supply duct. Return through 304L stainless main with low-particulate construction (continuously welded seams, no exposed Pittsburgh seams that could harbour dust).

Mirror silvering line — the corrosive mist department

Mirror silvering is the wet chemistry process that deposits a metallic silver layer on glass to make a mirror. The process is alkaline, ammoniacal, chloride-bearing and aggressive to almost every common construction material. HVAC duct material selection in the silvering department is non-negotiable: 316L stainless throughout, or FRP for the primary scrubber duct where the chemistry concentration justifies the cost. Galvanised fails in months; 304L is marginal and corrodes through within 3 to 5 years in heavy-use service.

Cleaning and tin sensitisation

Glass surface preparation starts with cerium oxide polishing (mild abrasive slurry) to remove any surface contaminant, followed by water rinse. The sensitisation step deposits a thin tin chloride (SnCl2) layer onto the cleaned surface — this provides the nucleation sites for the subsequent silver deposition. Tin chloride generates minor hydrochloric acid vapour at the spray nozzle, requiring 316L stainless source-capture LEV.

Silver nitrate cascaded deposition

Silver nitrate (AgNO3) solution is sprayed onto the sensitised glass surface alongside an ammonium hydroxide complexing agent and a reducing agent. The reducer is traditionally formaldehyde (HCHO) but increasingly substituted with glucose for occupational health reasons. The reduction reaction deposits metallic silver on the glass surface.

The cascaded spray generates an alkaline ammoniacal mist that captures through 316L stainless LEV hoods at each spray station, face velocity 0.8 to 1.2 metres per second. Trunk duct conveys to a packed-bed wet scrubber with caustic recirculation. Scrubber housing 316L stainless fabricated on the SB-ZF1500 stitchwelder with TIG-welded longitudinal seams for leak-class A air-tightness — the scrubber must contain the corrosive mist completely without seepage to the surrounding workspace.

Copper backing

After the silver layer is deposited, a copper backing layer is applied — either electroless copper deposition (chemistry similar to silver deposition with copper sulphate as the metal source) or sprayed copper paint. Electroless copper deposition shares the silvering line LEV manifold. Sprayed copper backing requires its own LEV station for the copper-paint atomisation.

Silver recovery

Silver is expensive and the silvering process is not 100 percent efficient. Operator-specific silver recovery from the scrubber blowdown and the floor washdown is the norm — typically precipitation with sodium chloride to form silver chloride which is filtered and reduced back to metallic silver for re-melting. Silver recovery from extract scrubber blowdown is the operator's metallurgical recovery process; the HVAC engineering simply provides the scrubber blowdown to the recovery station in 316L stainless piping.

Formaldehyde exposure monitoring

Where formaldehyde is used as the silvering reducer, occupational exposure monitoring is mandatory at the spray station operator's breathing zone. Safe Work Australia formaldehyde STEL is 1 ppm short-term, 8-hour TWA 0.3 ppm. Personal monitors during commissioning verify the LEV captures formaldehyde to below 0.3 ppm at the operator station with substantial margin. Glucose-substituted silvering lines drop the formaldehyde exposure to zero but increase the BOD loading on scrubber blowdown.

Mirror backing paint room

The silvered mirror passes from the silvering line through to the mirror backing paint room, where a protective paint coat is applied to the rear of the silver and copper layers to protect against atmospheric attack. The paint is typically a high-build alkyd or polyurethane at 30 to 50 percent volume-solid, applied by spray application. Paint room HVAC is dominated by VOC capture.

Downdraft spray booth

Downdraft spray booth construction with galvanised SBAL-V plenum walls captures the overspray at booth face velocity 0.4 to 0.5 metres per second. Plenum walls are 1.0 mm galvanised on Pittsburgh seam, SBAL-V scope. Extract through carbon adsorption bed or thermal oxidiser to satisfy state EPA licence VOC limits.

Solvent storage

Paint thinner storage (typically MEK, toluene or xylene depending on the paint chemistry) follows AS 1940 flammable and combustible liquids storage. Dedicated solvent store with bunded floor, mechanical exhaust at 6 to 10 air changes per hour, no electrical equipment without Ex rating, Class I Zone 1 hazardous area classification. Storage room HVAC duct in galvanised SBAL-V scope with bonded earthing and spark-resistant fan.

HF acid etching department — the fluoride scrubber

Hydrofluoric acid etching produces frosted decorative architectural glass and selectively etched surface treatment for signage and bespoke architectural applications. HF (typically 40 to 70 percent aqueous solution) is the most aggressive industrial acid in normal manufacturing use. It eats through carbon steel in minutes, attacks 304L slowly, challenges even 316L over decades, and is uniquely hazardous to bone calcium. Even a small skin exposure can be life-threatening. HF etching departments require dedicated engineering controls.

Department design

HF etching departments are physically separated from the rest of the plant by fire-rated walls and floors per AS 1530.4. Department ventilation runs at 12 to 15 air changes per hour with strong negative pressure (minus 15 to 25 Pa) to ensure no HF vapour migrates to adjacent occupied zones. Continuous fluoride monitoring at the operator breathing zone alarms at 2.5 mg per cubic metre Safe Work Australia WES. Personnel decontamination shower at the department exit.

Etching tank extract

HF etching tanks are typically polypropylene-lined or PVDF-lined steel tanks holding the acid bath. Each tank ventilates through a perimeter slot LEV at 1.0 to 1.5 metres per second capture velocity into a duct that runs to the dedicated fluoride scrubber. Duct material 316L stainless SBAL-V scope at 1.0 to 1.5 mm for the primary extract, or FRP (fibreglass-reinforced plastic, hand-laid by specialist composite shops) for very high-concentration service. No galvanised anywhere in the HF etching department airstream.

Fluoride scrubber design

The fluoride scrubber is a packed-bed wet scrubber with sodium hydroxide recirculation, sized for at least 99 percent fluoride removal across the design flow range. Scrubber housing 316L stainless or FRP. Demister downstream removes entrained scrubber liquid. Stack discharge tested quarterly per state EPA licence. Scrubber blowdown captures the calcium fluoride precipitate (lime treatment of the alkaline blowdown produces insoluble CaF2 which is then filtered) for disposal.

The scrubber housing is typically fabricated by an FRP composite shop or by a 316L stainless welded fabrication shop on the SB-ZF1500 stitchwelder for leak-class A construction. The associated 316L extract duct upstream of the scrubber is SBAL-V scope. The SBKJ scope split: SBAL-V handles the duct work, specialist welded fabrication handles the scrubber pressure-bearing vessel itself.

Automotive glass production HVAC

Automotive glass production in Australia is concentrated at Carlite (CSR brand) at Dandenong VIC, supplying windscreens and side glass to Holden, Toyota and Ford historically and increasingly to the imported-vehicle aftermarket. Replacement automotive glass workshops (O'Brien Glass, Novus Auto Glass, Smith & Smith) run smaller-scale operations across the national network. Automotive glass shares most architectural processor HVAC with two distinct additions.

Bending oven for curved windscreens

Automotive windscreens are gently curved to match the vehicle body line. The flat lite pair (inner and outer ply with the PVB interlayer between) is placed on a shaped tool nest and heated in a bending oven at 580 to 650 degrees Celsius until the glass slumps to the tool shape. Bending oven HVAC is dominated by overhead heat extract at 30 to 35 degrees Celsius personnel target through 304L stainless duct (SBAL-V scope), with operator pulpit refrigerated supply.

PVB film handling

PVB interlayer film is hygroscopic and must be held at climate-controlled storage (typically 20 to 22 degrees Celsius, 25 to 35 percent relative humidity) before use. PVB storage room HVAC runs as a small clean room — Class III filtered, dehumidified supply air, dedicated air-handling unit. Galvanised SBAL-V scope throughout.

Cutting hall humidity

Automotive cutting hall handles the windscreen wash before the lite pair is laminated. The cascaded fresh-water rinse adds significant humidity load on the return air. 304L stainless on horizontal runs within 3 metres of the wash line. Galvanised acceptable elsewhere in the cutting hall.

Sandblast etching for architectural finish

Sandblast etching for architectural decorative finish — frosted patterns, signage, custom textures — operates inside a dedicated booth at 1000 plus feet per minute air velocity (5 plus metres per second). Silica or garnet abrasive at 80 to 100 psi air pressure removes surface glass material. AS 3957 sandblast equipment standard applies plus NFPA 660 combustible-dust review for the spent abrasive plus glass dust mix.

Booth ventilation

Sandblast booth ventilation captures the abrasive plus dust mix at the booth floor through a dust collector hopper and a baghouse. Air velocity 5 to 8 metres per second in the booth ensures dust capture at the operator station. Booth ventilation rate sized at 100 to 200 ACH for the booth volume. Galvanised SBAL-V scope at 1.0 to 1.2 mm — heavier than standard HVAC due to abrasive wear.

Spark-resistant fan and explosion vent

Spark-resistant AMCA Type A fan with all-metal construction and no aluminium-on-steel rubbing surfaces. Bonded electrostatic earthing on every duct flange. Explosion vent on the dust collector hopper per NFPA 660 (formerly NFPA 484 for combustible metals where bronze or aluminium abrasive is used; NFPA 660 consolidated standard for silica or garnet abrasive at higher dust loadings).

Spent abrasive recovery

Spent abrasive plus dust is typically recovered and screened for re-use until particle size drops below the minimum effective abrasive (typically 5 to 10 cycles before disposal). Recovery system is outside HVAC duct scope but the dust collector hopper discharge to the abrasive recovery silo runs in galvanised SBAL-V scope.

Bent and slumped glass kilns

Bent and slumped glass for architectural curved applications — curved facade glass, glass dome lights, custom architectural feature glass — is produced in dedicated bending or slumping kilns at 600 to 700 degrees Celsius. The kiln holds the glass on a shaped tool for several hours, allowing the glass to slowly conform to the tool shape under gravity (slumping) or against the tool pressure (bending).

Specialist Australian operators include Slumpys Glass (Sydney, bespoke architectural) and selected operations at G.James and AGG. Total industry volume in Australia is small. HVAC profile is dominated by heat extract above each kiln through 304L stainless SBAL-V duct, with operator HVAC at 30 to 35 degrees Celsius ambient through galvanised SBAL-V supply.

QC laboratory HVAC — the climate-controlled environment

The plant QC laboratory runs the testing regime that demonstrates AS 2047, AS 1288, AS/NZS 2208, AS/NZS 4666 and product certification compliance. Optical performance (visible light transmittance, solar heat gain coefficient), dimensional accuracy, mechanical performance (impact resistance, ball-drop), thermal performance (U-value, R-value) and accelerated aging tests run in the lab.

Climate control

QC lab ambient targets 22 to 24 degrees Celsius, 45 to 55 percent relative humidity, plus or minus 1 degree Celsius and plus or minus 5 percent RH stability throughout the test cycle. Class III filtered supply air at 8 to 12 ACH through insulated galvanised SBAL-V supply duct, return through 304L stainless main, dedicated air handling unit with redundant N+1 chillers and humidifier.

Specialty test cells

The accelerated weathering test cell uses xenon arc or QUV (UV fluorescent) lamps to simulate years of solar exposure in days. The cell ambient runs at 50 to 70 degrees Celsius with controlled humidity. Test cell HVAC duct is 304L stainless SBAL-V scope. The salt spray cabinet (for chloride corrosion resistance testing on coated glass) runs at high humidity and chloride concentration — 316L stainless SBAL-V scope.

Worker amenity, canteen and admin HVAC

Worker amenities (locker rooms, showers, canteen, first aid) and admin (offices, meeting rooms, reception) run on separate air handling units from the production floor, completely isolated from any chemical extract or hazardous-area envelope. Standard commercial HVAC in galvanised SBAL-V throughout.

Locker rooms include mechanical exhaust to manage any chemical residue carried on PPE. Shower areas in galvanised SBAL-V supply with 304L stainless return on horizontal runs to resist condensate. Canteen ventilation per AS 1668.2 commercial kitchen exhaust requirements (see the commercial kitchen exhaust HVAC duct guide for the full scope). Office and meeting rooms at standard commercial 22 to 24 degrees Celsius, 6 to 8 ACH, Class III filtered.

Australian operators — what they specify

Knowing which operators specify what informs how an HVAC duct fabrication shop sizes its capacity. The Australian flat-glass landscape is concentrated and the major operators each have a distinct HVAC procurement pattern.

Viridian Glass (CSR + Saint-Gobain JV)

Viridian Glass is Australia's only float-glass primary manufacturer, with the Dandenong VIC float line as the flagship plant plus secondary processing at Ingleburn NSW and Erskine Park NSW. Viridian runs the full primary HVAC scope including tin-bath hazardous-area envelope plus secondary architectural processing. The Dandenong site is the largest single HVAC duct retrofit market in the Australian flat-glass sector.

HVAC retrofit projects at Viridian typically tender to mechanical services contractors during planned shutdown windows (the float line has a major shutdown every 8 to 12 years for furnace and tin bath rebuild). The duct scope is split: mechanical services contractor handles all personnel-zone HVAC, batch house dust collection, edge grinding mist, tempering and laminating area HVAC, IGU assembly clean area; specialist welded-fabrication contractor handles regenerator stack, furnace exhaust, autoclave pressure vessel and sputter chamber vacuum vessel.

G.James Glass and Aluminium

G.James is Australia's largest architectural processor, with the Brisbane HQ plus dedicated processing sites in every Australian state. Each G.James site runs a typical architectural processor scope — cutting, edging, tempering, laminating, IGU assembly — with selected sites adding silvering and sputter coating. HVAC retrofit demand at G.James is steady and well-managed, with the corporate engineering team coordinating standards across all state sites.

Australian Glass Group (AGG)

AGG at Dandenong VIC is the largest Australian-owned independent processor, with full architectural processing capability including in-house MSVD soft-coat sputter line. AGG specifies high-quality HVAC duct fabrication and has been a long-term SBKJ machinery customer through its mechanical services contractors.

Capral Aluminium

Capral at Bremer Park QLD and Erskine Park NSW operates as an integrated aluminium frame plus glass manufacturer, supplying complete window and door assemblies into the building industry. Capral's glass scope overlaps with architectural processors and shares the same HVAC profile — cutting hall, tempering, IGU assembly. Capral also runs aluminium extrusion and finishing on the same sites, which adds anodising, powder coating and aluminium machining HVAC scope — see the window and door aluminium joinery manufacturing HVAC duct guide for the parallel aluminium scope.

Stegbar, Bradnam's, Wideline, Trend

Stegbar (JELD-WEN), Bradnam's Windows and Doors, Wideline Windows and Trend Windows are the major national window and sliding-door fabricators. Each runs in-house glass cutting, tempering and IGU assembly alongside aluminium and timber frame manufacturing. HVAC retrofit demand is steady across all four operators, with state-based fabrication sites tendering duct work to local mechanical services contractors.

Lite Wall

Lite Wall at Tullamarine VIC is a dedicated IGU specialist supplying high-performance insulating glass units into the Victorian and interstate facade market. Lite Wall's IGU assembly area HVAC is the cleanest in any architectural processor outside the sputter coater building — Class III filtration with positive pressure plus 10 to 15 Pa, climate-controlled at 22 to 24 degrees Celsius and 40 to 50 percent RH. Lite Wall has been a long-term customer of mechanical services contractors running SBKJ machinery.

Carlite (CSR automotive glass)

Carlite at Dandenong VIC is the dominant Australian automotive glass manufacturer, supplying windscreens and side glass to the local vehicle assembly industry historically and to the imported-vehicle aftermarket today. Carlite's HVAC profile includes bending oven heat extract, laminating autoclave room, side-glass tempering hall, plus all the standard architectural processor zones.

Mirror Mate

Mirror Mate in Sydney is the largest Australian dedicated custom mirror specialist, running silvering, copper backing and mirror backing paint on bespoke project work. Mirror Mate's HVAC profile is dominated by 316L stainless silvering-line extract and paint room VOC capture.

Smaller specialists

Slumpys Glass (Sydney, bespoke bent and slumped), Stained Glass Studio (Melbourne, stained glass restoration), Allglass (NSW), Vetro Glass (VIC), Total Glass (NSW), Glascorp (Sydney) and Apex Glass (NSW) round out the Australian processor sector. Each operates a subset of the full HVAC scope appropriate to its product mix. SBKJ supplies machinery into the mechanical services contractors serving these smaller specialists as well as the large operators.

O'Brien Glass, Novus, Smith & Smith — replacement automotive

O'Brien Glass (Belron group), Novus Auto Glass and Smith & Smith run automotive glass replacement workshops across the national network. Workshops are small (typically 1 to 3 service bays) and HVAC is straightforward general workshop ventilation, similar to the automotive paint booth HVAC duct guide spec at the smaller end. SBAL-V galvanised throughout.

Materials selection across the plant

Material selection across an Australian flat-glass plant spans the full range from low-cost galvanised in general HVAC up to specialty 316L stainless and FRP in HF etching and silvering. The decision matrix is straightforward once the chemistry is identified.

Galvanised G90 (Z275)

Galvanised G90 (276 grams per square metre zinc coating per ASTM A653, equivalent to AS/NZS Z275) is the workhorse material for general HVAC duct in flat-glass plants. Acceptable for personnel-zone supply and return, cutting hall HVAC, tempering area operator pulpit supply, laminating autoclave room ambient, IGU assembly clean area supply, batch house source-capture mains (dry silica service), control rooms, electrical rooms, admin and amenity zones. Limited to 80 degrees Celsius continuous service. Not suitable for silvering line extract, HF etching service, tin-bath proximity returns, copper backing, mirror backing paint room return, or any humid corrosive zone. Forms readily on the SBAL-V auto duct line at 0.5 to 1.5 mm. For a complete galvanised versus stainless comparison see the galvanised vs stainless steel duct guide.

304L stainless

304L stainless is the default upgrade material for any service that exceeds galvanised limits but does not require full chloride resistance. Tempering furnace heat extract, on-line CVD coating extract (proximity), edge grinding wet department LEV, washing line return air, automotive bending oven extract, laminating cleaning station extract, IGU assembly return air, butyl extrusion LEV, polysulphide extrusion LEV, lehr corridor returns within 3 metres of the lehr wall. 304L is preferred over plain 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 to 1.5 mm.

316L stainless

316L stainless is the high-corrosion upgrade material with added molybdenum content providing chloride resistance. Mandatory for silvering line extract (alkaline ammoniacal chloride-bearing mist), HF etching department duct, copper backing extract, ion-exchange room (chemical strengthening of consumer glass), sputter chamber wet wash line return, and tin-bath roof penetration LEV where chloride contamination is suspected. Forms on SBAL-V at 0.6 to 1.5 mm with the same tooling as 304L. SBKJ supplies stainless coil sourced from Australian or Asia-Pacific mill stockists with NACE MR0175 acceptance certification where the service warrants.

Fibreglass-reinforced plastic (FRP)

FRP duct is occasionally specified for very high-corrosion service where stainless is not economic. The primary application is HF etching primary extract — vinyl ester FRP construction handles HF concentrations up to 40 percent. FRP duct is hand-laid or filament-wound by specialist composite shops, outside SBKJ machinery scope. See the composite manufacturing HVAC duct guide for FRP fabrication detail.

Aluminium

Aluminium duct is rarely used in flat-glass plant HVAC because galvanised is cheaper and stainless is more durable, with no service profile where aluminium uniquely outperforms. The exception is selected cleanroom applications in specialty glass production where aluminium's surface smoothness aids low-particulate operation.

Mild steel welded heavy gauge

Mild steel at 1.5 to 3.0 mm thickness with welded fabrication is reserved for high-temperature furnace exhaust (regenerator stack, melt furnace flue gas duct), lehr stack exhaust, autoclave pressure vessels (laminating, heat-soak oven internal), and sputter chamber vacuum vessels. Outside SBKJ standard machinery scope, fabricated by submerged-arc welding shops with ASME Section IX qualified procedures. Refractory-lined construction is used where exhaust temperatures exceed 600 degrees Celsius continuous.

SBKJ machinery for flat-glass plant duct fabrication

A mechanical services contractor building dedicated duct fabrication capacity to serve Australian flat-glass plant projects needs a specific machinery configuration. SBKJ Engineering Team has refined the recommendation across multiple Viridian, G.James, AGG and Capral projects.

SBAL-V auto duct line — the dual-mode workhorse

The SBAL-V auto duct production line is the centrepiece of the duct fabrication shop. SBAL-V handles 0.5 to 1.5 mm coil at width 1250 mm (model SBAL-V-1250J) or 1500 mm (model SBAL-V-1500J), forming speed 16 metres per minute, total power 87 kW, weight approximately 16 tonnes, operating 380V 50 Hz three-phase, footprint 14000 by 2000 by 1800 mm (1250J model) or 14000 by 2200 by 1800 mm (1500J model). Output is finished rectangular duct ready for corner blocks and packing, with TDF flange forming, beading and notching integrated into a single coil-to-duct line operated by 2 to 3 staff.

Critical for flat-glass plant work: dual-mode galvanised plus 316L stainless capability on the same line with 30-minute changeover. This single specification covers 65 to 70 percent of the total HVAC duct length in a typical flat-glass plant fit-out. SBAL-V output meets AS/NZS 4254.2 pressure class C up to 2500 Pa as standard on Pittsburgh seam. For a full SBAL-V vs SBAL-III comparison see the SBAL-V vs SBAL-III comparison guide.

SBSF-1525 round-duct flanging machine

The SBSF-1525 round-duct flanging machine forms round flanges on spiral pipe ends from 100 to 1525 mm diameter. Round spiral pipe is the most material-efficient construction for return air mains and long horizontal runs in cutting halls, lehr corridors and IGU assembly areas. Round duct carries 30 to 40 percent less material per unit pressure drop than equivalent rectangular at long lengths. SBSF-1525 scope in a flat-glass plant typically covers 15 to 20 percent of total HVAC duct length as round return mains and selected supply runs.

SB-ZF1500 stitchwelder for stainless plenum and scrubber housing

The SB-ZF1500 stitchwelder closes the longitudinal seam on stainless duct at up to 1.6 mm thickness, producing leak-class A air-tight construction required for silvering line extract, HF etching duct, scrubber housings and any 316L pressure-class-D service. Stitchwelding is the SBKJ alternative to TIG welding for high-volume seam closing on stainless duct — faster than TIG, equivalent leak-tightness at the seam pitch specified, suitable for the SBAL-V output gauge range.

SB-ZF1500 scope in a flat-glass plant typically covers 5 to 8 percent of total HVAC duct length but disproportionately high value because welded leak-class A construction is the highest-quality output the SBKJ machinery range produces. Scrubber housings for silvering, HF etching and CVD coating extract are built on the SB-ZF1500 plus SBLR-600 welder combination.

SBLR-600 laser welder for precision welds

The SBLR-600 handheld laser welder handles precision welded joints on stainless duct elbows, transitions, custom fittings and scrubber housing details. Laser welding is faster than TIG for thin-gauge stainless and provides a narrower heat-affected zone, reducing sensitisation risk on 316L service. SBLR-600 scope in a flat-glass plant typically covers fitting and custom-detail welding rather than primary duct seam welding (which is the SB-ZF1500 stitchwelder's role).

SBPC1500 plasma cutter for 316L sheet

The SBPC1500 plasma cutter handles cut-to-size operations on 316L stainless sheet for scrubber baffles, custom fitting blanks and any heavy-gauge precision cutting that exceeds the SBAL-V scoring head capability. Plasma cutting is faster than abrasive waterjet for stainless and provides comparable edge quality once the consumables are dialled in. SBPC1500 scope is supplementary to the SBAL-V scoring head for the 5 to 10 percent of duct work that requires off-line cut-to-size processing.

Spark-resistant fan specification

Every fan inside the float-bath hazardous-area envelope, every fan in the cullet processing zone subject to NFPA 660 review, every fan in the sandblast booth dust collection train, and every fan in the LPG-fired furnace burner train requires spark-resistant construction. AMCA Type A (all-metal construction with no aluminium-on-steel rubbing surfaces) is the default specification. Type B (aluminium impellers with non-sparking liners on steel housings) is acceptable in Zone 2 only. Fans are specified separately from SBKJ ductwork machinery scope and are sourced by the mechanical services contractor from AMCA-certified fan suppliers.

Outside SBKJ machinery scope

Three categories sit outside SBKJ standard machinery scope and require specialist welded-fabrication shops. First, high-temperature furnace exhaust at 1.5 to 3.0 mm welded mild steel or refractory-lined plate (regenerator stack, lehr stack, tempering furnace exhaust). Second, MSVD sputter chamber vacuum manifolds at 316L vacuum vessel construction. Third, laminating autoclave pressure vessels (these are bought-in pressure vessels from autoclave specialists, not fabricated on-site). 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, SBSF-1525, SB-ZF1500, SBLR-600 and SBPC1500, and which go to subcontracted welded fabrication or to bought-in equipment.

Project lead time and delivery into Australia

Flat-glass plant projects run on capital windows. Major shutdowns (4 to 6 weeks for float line furnace and tin bath rebuild) recur every 8 to 12 years per line. Architectural processor capacity expansions (new tempering line, new IGU assembly area, new sputter coater building) recur on a 3 to 5 year tempo at the major sites. HVAC fit-out projects are scheduled into these capital windows and lead time discipline is critical.

SBKJ machinery lead times

Standard SBAL-V auto duct line: 60 to 90 days from 30 percent T/T deposit to ex-works ready, plus 25 to 35 days ocean freight to Melbourne, Sydney, Brisbane or Adelaide. SBSF-1525 round-duct flanging machine: 45 to 60 days plus shipping. SB-ZF1500 stitchwelder: 60 to 75 days plus shipping. SBLR-600 laser welder: 60 to 75 days plus shipping. SBPC1500 plasma cutter: 45 to 60 days plus shipping. Total project window from purchase order to commissioned line at the customer's Australian site is typically 16 to 22 weeks for a complete duct fabrication shop dedicated to a flat-glass plant retrofit.

Coordination with shutdown windows

Viridian, G.James, AGG, Capral and Lite Wall mechanical services contractors typically order SBKJ machinery 6 months ahead of their next plant capital window, allowing 16 to 22 weeks for machine delivery and commissioning plus 4 to 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 and inland transport

SBKJ machinery routinely ships to Melbourne (for Viridian Dandenong, AGG, Lite Wall, Carlite, Stained Glass Studio), Sydney (for Viridian Ingleburn and Erskine Park, G.James NSW, Allglass, Total Glass, Glascorp, Apex Glass, Mirror Mate, Slumpys, Stegbar NSW, Bradnam's NSW), Brisbane (for G.James Brisbane HQ, Capral Bremer Park, Bradnam's QLD) and Adelaide (for Stegbar SA). 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 Australian flat-glass HVAC duct fabricators

The SBKJ Engineering Team at Box Hill North VIC has supplied SBAL-V, SBSF-1525, SB-ZF1500, SBLR-600 and SBPC1500 machinery into mechanical services contractors building duct fabrication capacity for Australian flat-glass plant projects. 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, SBSF-1525 diameter range, SB-ZF1500 stitch parameters and SBLR-600 capability matched to the duct fabrication scope. Itemised by lineal metres per pressure class and material across galvanised, 304L stainless, 316L stainless and welded subcontract scope.
• FAT against flat-glass plant duct samples. Factory Acceptance Test before shipment runs the contractor's nominated coil through a full production cycle on the SBAL-V — galvanised mode, 304L mode and 316L mode — with tolerance verification against AS/NZS 4254.2 pressure class C requirements and leak-class A on welded seam samples.
• Installation supervision in Australia. SBKJ engineers on site at the contractor's shop for 5 to 10 days for installation, mechanical commissioning and electrical commissioning, working with the contractor's PLC integrator on any custom interlock requirements.
• Operator and maintenance training. 8 to 16 hours operator training and 4 to 8 hours maintenance training in English, with a written commissioning report. Training covers stainless mode changeover procedure, tooling regrind schedule, PLC backup procedure and the stitchwelder seam-quality check protocol.
• 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 plus years from first delivery.
• 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 within a 12-hour reply window.

Get an itemised SBKJ quote for your flat-glass plant duct fabrication project →

How flat-glass HVAC compares to adjacent heavy industries

For HVAC duct fabricators serving multiple heavy-industry sectors, flat-glass HVAC sits at the upper-intermediate complexity tier — more demanding than general commercial HVAC and most light industrial, less demanding than primary semiconductor fab or pharma sterile manufacturing.

vs primary glass manufacturing (container, fibreglass)

Container and fibreglass glass manufacturing share the batch house, melt furnace and lehr scope with flat glass primary float, but lack the tin-bath hazardous area and the silvering, HF etching and IGU assembly scope. See the container and fibreglass glass manufacturing HVAC duct guide for the full comparison.

vs window and door aluminium joinery

Window and door aluminium joinery shares the cutting, edging and IGU assembly scope with flat-glass architectural processors, but adds aluminium extrusion, anodising, powder coating and aluminium machining HVAC. Capral, Stegbar, Bradnam's, Wideline and Trend operate at the intersection. See the window and door aluminium joinery manufacturing HVAC duct guide for the aluminium-specific scope.

vs automotive paint booth

Automotive paint booth HVAC at body shops and OE assembly lines shares the spray-booth and VOC-capture scope with the flat-glass mirror backing paint room and laminating cleaning station, but at much larger scale and with isocyanate hazard from polyurethane finishes. See the automotive paint booth HVAC duct guide.

vs cement plant

Cement plant HVAC shares the dust-loading and high-temperature stack scope with the flat-glass batch house and melt furnace, at 3 to 5 times the dust collection volume. See the cement plant HVAC duct guide for the comparison.

vs foundry iron and steel casting

Foundry iron and steel casting HVAC handles higher process temperatures (steel BOF and EAF tap temperatures at 1650 to 1700 degrees Celsius) but lower chemical complexity than the flat-glass silvering, HF etching and sputter coating zones. See the foundry iron and steel casting HVAC duct guide.

Common procurement mistakes on flat-glass HVAC projects

SBKJ engineers see the same handful of procurement mistakes repeatedly on flat-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. Flat-glass plants need 20 to 30 percent of their duct in 304L or 316L stainless (silvering, HF etching, tempering, on-line CVD proximity, cure ovens). A dual-mode SBAL-V handles galvanised, 304L and 316L on the same line with 30-minute changeover. The incremental cost of dual mode at order time is recovered on the first 316L silvering line project.

Mistake 2 — Underestimating the welded-fabrication scope split

Procuring SBKJ machinery for 100 percent of project duct then discovering at fit-out that 5 to 10 percent (the regenerator stack, lehr stack, autoclave pressure vessel, sputter chamber) must be subcontracted at a premium. The scope split should be in the quotation, not discovered on site.

Mistake 3 — Galvanised on silvering line extract

Saving 40 percent material cost by specifying galvanised on silvering line extract. Galvanised corrodes through in 3 to 6 months in alkaline ammoniacal chloride service. 316L stainless is the only durable choice. The galvanised "saving" is wiped out by the first re-fit at year one.

Mistake 4 — 304L on HF etching duct

Specifying 304L instead of 316L on HF etching department duct. 304L is attacked by HF over a few years and the consequences of a leak in HF service are severe (bone-calcium fluoride poisoning is a notifiable industrial fatality risk). 316L stainless or FRP are the only acceptable specifications for HF service.

Mistake 5 — Forgetting hazardous-area zoning at the tin bath

Specifying standard non-spark-resistant fans, non-bonded duct flanges and standard motor IP rating on tin-bath proximity HVAC. The tin bath envelope is Zone 1 hazardous area under AS/NZS 60079.10.1 and the spec must include Ex e or Ex d fittings, spark-resistant fans, bonded duct flanges and continuous hydrogen monitoring. Retrofitting to compliance after commissioning costs 3 to 5 times the original specification difference.

Mistake 6 — Missing the IGU assembly clean area pressure

Designing the IGU assembly area at neutral pressure instead of plus 10 to 15 Pa positive. The single most common cause of IGU warranty claims is dust contamination at the primary seal interface during assembly — preventable with the correct positive pressure specification at design stage.

Mistake 7 — 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 to 5 years; the correct specification is 1.0 to 1.2 mm galvanised, well within SBAL-V capability.

Mistake 8 — 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 to 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 9 — Skipping the FAT

Skipping the Factory Acceptance Test on the assumption that the SBAL-V will "just work" on the contractor's coil. Stainless coil from different mill sources behaves differently through the Pittsburgh-seam tooling; the FAT verifies acceptable seam quality before shipment, and is mandatory on every SBKJ auto duct line.

Mistake 10 — Forgetting NFPA 660 on cullet and sandblast

Treating cullet processing dust collection and sandblast booth dust as identical to virgin batch dust collection. Cullet contains organic residue (label paper, plastic, food residue) and falls within NFPA 660 combustible dust scope; sandblast generates a metal-silica-glass dust mix with deflagration potential. Explosion vents, isolation valves and bonded electrostatic earthing are mandatory and easily forgotten at design stage.

FAQ

What is the major hazardous-area concern in flat-glass primary manufacturing HVAC design?

The float-glass tin bath hydrogen atmosphere. The bath is held under nitrogen plus 4 to 7 percent hydrogen to prevent tin oxidation; AS/NZS 60079.10.1 classifies the bath roof penetrations as Zone 1 (flammable gas likely in normal operation). Every duct, fan and electrical fitting in the zoned envelope must be Ex-rated, spark-resistant and bonded for electrostatic dissipation, with continuous hydrogen monitoring at 25 percent of LEL alarm threshold.

Why is 316L stainless mandatory for mirror silvering line extract?

Silvering uses silver nitrate (AgNO3), ammonium hydroxide, sodium hydroxide and a reducer (formaldehyde or glucose) in cascaded spray on the moving glass surface. The mist is alkaline, ammoniacal and chloride-bearing. Galvanised fails in months from zinc dissolution; 304L is challenged over 3 to 5 years and corrodes through at flange welds; 316L resists all three attack modes with the added molybdenum content. The SBAL-V handles 316L on the same coil mode as 304L and galvanised.

What HVAC ductwork is within SBKJ machinery scope and what is outside?

SBKJ duct machinery (SBAL-V, SBSF-1525, SB-ZF1500, SBLR-600, SBPC1500) handles 0.5 to 1.6 mm galvanised, 304L stainless, 316L stainless and aluminised sheet formed into rectangular, oval and round duct. High-temperature furnace exhaust at 1.5 to 3.0 mm welded mild steel or refractory-lined plate (regenerator stack, lehr stack, tempering furnace exhaust) is outside scope. MSVD sputter chamber vacuum manifolds and laminating autoclave pressure vessels are also outside scope and require specialist welded-fabrication shops with ASME Section IX qualified procedures.

Can SBKJ machinery form 316L stainless duct for HF etching service?

Yes. The SBAL-V forms 316L stainless from 0.6 to 1.5 mm with 30-minute changeover from galvanised mode. The SB-ZF1500 stitchwelder closes the longitudinal seam for leak-class A air-tight construction. The SBLR-600 handles precision welds on fittings and custom details. The SBSF-1525 forms round flanges on 316L spiral pipe. Together, the SBKJ machinery range covers the full HF etching department duct scope upstream of the fluoride scrubber, with the scrubber housing itself fabricated on the SB-ZF1500 plus SBLR-600 combination.

What is the typical lead time for SBKJ machinery to an Australian flat-glass project?

SBAL-V auto duct line 60 to 90 days from deposit to ex-works ready, plus 25 to 35 days ocean freight. SBSF-1525 round-duct flanging 45 to 60 days. SB-ZF1500 stitchwelder 60 to 75 days. SBLR-600 laser welder 60 to 75 days. SBPC1500 plasma cutter 45 to 60 days. Total project window from purchase order to commissioned line is typically 16 to 22 weeks. Viridian, G.James, AGG and Capral mechanical services contractors order 6 months ahead of plant capital windows.

How does AS 1668.2 apply to flat-glass plant HVAC?

AS 1668.2-2024 Section 5 governs personnel-zone ventilation (cutting hall, IGU assembly, tempering operator pulpit, lehr corridor, control rooms). Section 6 governs specific exhaust applications (silvering line corrosive mist, HF etching extract, mirror backing paint VOC capture). Pressure class C (up to 2500 Pa) covers batch house dust collection mains; class A through B covers personnel comfort runs. SBAL-V output meets AS 4254 pressure class C as standard on Pittsburgh seam, with SB-ZF1500 stitchwelded seams for class D and leak-class A.

Which Australian operators are the major flat-glass HVAC procurement targets?

Viridian Glass (CSR + Saint-Gobain JV, Dandenong VIC float line plus Ingleburn and Erskine Park NSW secondary processing). G.James Glass and Aluminium (Brisbane HQ plus sites in every state). Australian Glass Group AGG (Dandenong VIC). Capral Aluminium (Bremer Park QLD and Erskine Park NSW). Stegbar, Bradnam's, Wideline, Trend (national window and sliding-door footprints). Lite Wall (Tullamarine VIC IGU specialist). Carlite (CSR automotive glass Dandenong VIC). Mirror Mate (Sydney custom mirror). Slumpys Glass (Sydney bent and slumped). O'Brien Glass, Novus, Smith & Smith (national automotive glass replacement).

What materials are specified for HVAC duct in an IGU assembly area?

Galvanised G90 (Z275) for personnel-zone supply and return air. 304L stainless on horizontal returns within 3 metres of any wash line. The IGU assembly area runs at positive pressure plus 10 to 15 Pa to keep external dust and lint out of the primary butyl seal interface. Class III filtered supply at 8 to 10 air changes per hour through insulated galvanised SBAL-V supply, return through 304L stainless main with continuously welded seams to minimise lint-trapping surfaces.