1. Why thermal-station HVAC is its own discipline
An HVAC duct run inside a coal-fired or gas-fired power station bears almost no resemblance to the duct run that sits above the ceiling of a commercial office tower. The temperatures are higher, the gases are more aggressive, the particulate load is heavier, the fire risk is graver, and the regulatory overlay is denser. A 1,000 MW thermal plant is a fully integrated thermo-chemical reactor wrapped in a 70-metre-tall steel frame — and every cubic metre of that frame is conditioned, exhausted, purged or scrubbed by ductwork that has to keep working for thirty to fifty years across acid attack, fly-ash abrasion, vibration cycling, fault transients on the grid and the occasional 47-degree summer afternoon in the Hunter Valley or the Latrobe Valley.
Specifying that ductwork against the wrong standard, or with the wrong material, fails predictably. Galvanized G300 hangs on in the turbine hall outside-air make-up for the life of the asset; the same gauge dropped downstream of the air heater turns into a salt-stalactite museum in 18 months. The discipline of thermal-station HVAC is choosing the right material for the right zone, building it on the right machine, joining it with the right seam and signing it off against the right code. This guide walks the entire envelope, from the turbine hall down to the FGD absorber outlet, and from a new combined-cycle gas plant on Day One through to a decommissioned coal station being repurposed as a battery energy storage system or a synchronous condenser.
The Australian thermal fleet matters more than its declining share of the National Electricity Market suggests. As of mid-2026 the NEM still relies on roughly 21 GW of coal-fired capacity and around 9 GW of gas-fired capacity to underwrite firming, frequency response and inertia while the inverter-based renewable rollout accelerates. The Australian Energy Market Operator's Integrated System Plan (AEMO ISP) sets the orderly retirement schedule — Liddell already closed in 2023, Eraring in 2027, Yallourn in 2028, Bayswater by 2033, Loy Yang A by 2035 — but every one of those plants has to be operated reliably until its closure date, and then deconstructed safely, and in many cases progressively repurposed. The HVAC scope across that transition is non-trivial.
2. The Australian regulatory stack for thermal-station HVAC
Before specifying a single metre of duct, the engineer has to internalise the regulatory stack. The eight standards below cover at least 90 percent of the HVAC questions that come up across a coal or gas station's life cycle. They are listed in roughly the order they apply across the project envelope.
AS 1668.1 — Fire and smoke control
AS 1668.1 is the Australian fire-and-smoke standard for mechanical ventilation systems in buildings. Even in an industrial power station, AS 1668.1 still governs the design of fire-isolated stair pressurisation systems, smoke spill ducts above the turbine hall, smoke control in the control building, and the motorised fire dampers that separate fire zones identified on the GA drawing. Practical implications for the duct fabricator: smoke spill ducts have to be rated for the temperature class assigned by the fire engineer (typically 200 °C / 600 °C / 1,000 °C for two-hour duration), and joints have to survive that temperature class without failure. Carbon steel duct with welded seams is standard; galvanized lock-form is not acceptable above 200 °C.
AS 1668.2 — Mechanical ventilation for acceptable indoor air quality
AS 1668.2 sets the outside-air rates, recirculation limits and contaminant control rules for occupied spaces. In a power station that means the control room, the relay rooms, the workshop bays and the staff amenities. The turbine hall floor is treated as an industrial space and falls under different criteria, but every occupied space inside the boundary has to meet AS 1668.2. Practical implication: the fabrication shop has to be able to produce small-diameter, low-pressure ductwork in galvanized steel for the office stack on the same project where it is producing 1.5 mm 316L for the FGD outlet — single-line flexibility matters.
AS 1668.4 — Natural ventilation
AS 1668.4 covers natural ventilation, including the louvre area, stack effect calculations and door opening allowances. In a coal-fired station the turbine hall almost always supplements mechanical ventilation with carefully sized roof monitors and high-level louvres so that on a 47 °C summer day the residual generator heat can dissipate by stack effect even if half the supply fans trip. The HVAC engineer's job is to make the louvre arrays and any motorised dampers serving them survive cyclic dust loading from coal handling without seizing.
AS/NZS 60079 — Hazardous areas
AS/NZS 60079 is the hazardous-area standard for atmospheres potentially containing flammable gases, vapours or combustible dusts. In a thermal station it applies to: the natural gas receiving station and turbine fuel skid in a combined-cycle plant, the hydrogen storage and supply system serving a hydrogen-cooled generator, the pulverised-coal mills and pulverised-coal pipelines, the diesel start-up fuel area, the lubrication oil reservoirs, the ammonia injection skid for SCR, and the battery rooms in the station DC system. Each zone is classified Zone 0, Zone 1 or Zone 2 (gas) or Zone 20, Zone 21, Zone 22 (dust), and every electrical accessory inside that zone — including motorised damper actuators, gas detectors and fans — must carry a matching Ex certificate. The duct fabricator's responsibility is to provide equipotential earthing across every flange joint in a hazardous zone so that static does not accumulate; that is one bonded copper strap or stainless wire across every TDF flange and every bolted angle joint.
AS 5034 — Installation and safety of secondary batteries in buildings
AS 5034 governs the installation of secondary batteries inside buildings — historically lead-acid station batteries, now also valve-regulated lead-acid (VRLA) and lithium chemistries in modern installations. Lead-acid float-charging releases hydrogen, which is an AS/NZS 60079 Zone 2 hazard whenever the lower flammable limit can be exceeded. The HVAC consequence is that battery rooms must have either natural ventilation through high-level louvres or mechanical exhaust ductwork sized to keep hydrogen concentration below 2 percent at any time the battery is float-charging. Typical Australian designs use mechanical exhaust at 1-2 air changes per hour, with a gas detector that escalates to 8-10 ACH if hydrogen is detected. The exhaust duct goes to atmosphere, never back into a recirculation loop. Stainless steel is standard for the discharge ductwork to handle any incidental sulphuric acid mist.
IEEE 484 — Stationary battery installation
IEEE 484 is the international companion to AS 5034 for recommended practice on installing vented lead-acid batteries for stationary applications. Together AS 5034 and IEEE 484 define the spacing, ventilation, eyewash and personnel safety requirements that the battery room HVAC must support. The duct designer's job is to provide redundancy on the exhaust fan — N+1 minimum — and a fail-safe damper position so that on power loss, the room is still ventilated by stack effect through the dampers in their fail-open state.
NFPA 850 — Fire protection for electric generating plants
NFPA 850 is the US-origin fire protection standard for electric generating plants and high-voltage direct-current converter stations. Australian operators reference NFPA 850 alongside AS 1668.1 because NFPA 850 contains plant-specific guidance that AS 1668.1 lacks — coal pulveriser fire protection, transformer cooling oil spill containment, hydrogen-cooled generator purge sequencing, cable tray fire stops. From an HVAC perspective NFPA 850 drives the layout of fire-zone boundaries, the location of motorised fire dampers, the design of smoke-removal fans for the cable basement, and the ventilation purge sequence for the generator hydrogen system at start-up and shutdown.
NFPA 56 — Cleaning of combustible gas piping
NFPA 56 covers the safe cleaning of fuel gas piping, especially during combined-cycle commissioning when the gas turbine fuel piping has to be air-blown or steam-blown to remove construction debris before first fire. Although it is a piping standard not a ducting one, NFPA 56 imposes constraints on the temporary exhaust ductwork used to vent the cleaning medium safely outside the gas turbine hall. The duct fabricator's role is to supply temporary high-velocity carbon steel ducting with bolted flanges for the cleaning run, sized for the air or steam blow rate, and disposed of after commissioning.
Beyond these eight, the broader Australian standards stack also includes AS 4024 for machinery safety (relevant to coal handling conveyors and the dust collection ducts that serve them), AS/NZS 4865 for the safe design and operation of combustible-dust extraction systems, AS/NZS 4254 for ductwork gauge and pressure class, AS/NZS 1668.1's appendices on smoke control, and the various AEMO connection agreement clauses that govern the auxiliary system reliability indices.
3. Zone-by-zone HVAC reference — coal-fired station
The cleanest way to organise the duct specification is zone by zone. Each zone has its own temperature regime, particulate load, dew-point profile, fire risk and code reference, and each one drives a different material and seam choice. The matrix below covers a generic 660 MW supercritical brown-coal or black-coal unit.
3.1 Turbine hall — the largest ventilated volume
The turbine hall is the dominant ventilated volume in any thermal station. For a 200-500 MW turbine the hall is typically 60-80 metres long, 25-30 metres wide and 30-40 metres tall, with the high-pressure, intermediate-pressure and low-pressure turbines on a single concrete pedestal and the generator at the cold end. The thermal load that drives the HVAC design is the parasitic heat rejected by the generator, the turbine casings, the oil coolers and the steam piping — broadly 1-2 percent of the unit's electrical output for the generator alone, plus a similar contribution from the turbine and piping radiative losses. A 500 MW unit therefore rejects 5-10 MW of sensible heat into the surrounding hall continuously.
On top of generator heat the hall absorbs solar gain through the steel cladding (10-30 W/m² depending on wall colour and insulation), heat from the lighting and crane motors, and infiltration from open dock doors and personnel doors. The combined latent and sensible load summed up against a Hunter Valley summer day of 38 °C ambient drives the engineered ventilation rate to 8-12 air changes per hour. For a 60 × 30 × 35 m hall (63,000 m³) that is 504,000 to 756,000 m³/h, or 140,000 to 210,000 L/s. Larger units at 500 MW commonly run 250,000-450,000 L/s in summer.
The supply strategy is almost always tempered outside-air make-up at floor level (no recirculation, no cooling coil for industrial halls in temperate Australia), with exhaust fans at the crane rail level taking the hottest stratified air out through the roof or upper sidewall. Make-up is usually filtered to G4 minimum to keep coarse dust out of the lubrication systems. Galvanized G300 to AS/NZS 4254 is the standard duct material throughout the turbine hall — temperature exposure is benign, the air is clean by industrial standards, and the duct runs are long, so cost matters. SBKJ specifies SBAL-V auto duct line output in galvanized 0.6-0.8 mm for low-pressure supply runs (up to 500 Pa) and 0.8-1.0 mm for medium-pressure exhaust (500-1,000 Pa).
Two complications are worth flagging. First, the generator is often hydrogen-cooled — the cooling medium inside the generator casing is hydrogen at about 4 bar gauge, with a sealing oil system at the shaft glands. Around the hydrogen receiving and distribution skid, AS/NZS 60079 hazardous-area rules apply, and the duct accessories within that zone must be Ex-rated. Second, the lube oil console under the turbine bearings carries a fire load measured in tonnes of oil and a fire risk per NFPA 850; smoke spill ductwork above the lube oil console is typically welded carbon steel rated to 600 °C for two hours.
3.2 Boiler house — high temperature, low humidity, dust suppression
The boiler house surrounds the steam generator and is dominated by radiative heat from the boiler casing, the steam drums and the high-pressure piping. Surface temperatures on the boiler casing rarely exceed 60 °C thanks to internal refractory and ceramic insulation, but the air temperature inside the boiler house can reach 50-55 °C in summer at the upper elevations. Ambient humidity is low because the air is heated continuously and any moisture is driven off rapidly.
Two duct systems share the boiler house. The first is general ventilation — typically natural ventilation through high-level roof monitors with motorised dampers, supplemented by spot mechanical exhaust at the burner front and the soot-blower lance access platforms. Carbon steel duct with welded seams is preferred over galvanized at the upper elevations because the long-term temperature is on the edge of zinc's service envelope (above 200 °C the zinc starts to oxidise and white-rust). The second is local dust suppression. Even with electrostatic precipitators and bag filters downstream of the boiler exit, fugitive coal dust accumulates around the burner front, the mill outlets and the soot-blower access. Localised dust extraction with HEPA-grade media is part of the AS 4024 machinery safety scope and the AS/NZS 4865 combustible dust scope.
Practical duct specification: 1.2 mm carbon steel with continuous TIG-welded seams from SBKJ's TIG seam welder, hot-dip galvanized after fabrication where service temperature stays below 200 °C, or left as bare carbon steel above 200 °C and managed with paint maintenance. The dust extraction system itself is a separate scope of work driven by AS/NZS 60079 hazardous-area Zone 21 (combustible dust), with explosion-vented baghouses, rotary airlocks at the dust collection cone, and earth bonding across every duct joint to dissipate static.
3.3 Control building — clean conditioned air, AS 1668.2 compliance
The control building houses the distributed control system (DCS), the unit control room, the relay rooms, the cable mezzanines, the operator amenities and the supervisory engineering offices. It is conditioned to office-grade standards — 22 ± 1 °C, 50 ± 10 percent relative humidity, AS 1668.2 outside-air rates — by a packaged chiller plant feeding fan coil units or air handling units. The duct material is conventional galvanized G300, AS/NZS 4254 gauges, TDF flanges, rectangular ducts up to 1,000 Pa pressure class.
One detail worth attention is positive pressurisation. The control building is designed to run at +25 Pa to +50 Pa relative to the turbine hall so that contaminated air from the hall cannot infiltrate the control building. The supply ductwork has to deliver about 10-20 percent more flow than the exhaust ductwork extracts, and the leakage rate of the supply ducts has to be tightly controlled. AS/NZS 4254 Class B leakage testing is the minimum, with Class A often specified for the supply trunks feeding the relay rooms where positive pressure is critical to keep coal dust out of the relay panels.
3.4 Coal handling — dust collection per AS 4024 and AS/NZS 4865
Coal arrives at the station by rail, conveyor or barge depending on the location, and travels through a stack-out yard, a reclaimer, a system of conveyors, transfer towers, vibrating screens, crushers, and finally a stockpile feed into the boiler. Every transfer point is a dust source. The HVAC scope for coal handling is dust extraction, not occupancy ventilation — the goal is to capture the fugitive coal dust at the source, transport it through duct runs to a bag filter, and return clean air to atmosphere.
Standards: AS 4024 governs the machinery safety of the conveyors and the dust collection equipment. AS/NZS 4865 governs the safe design and operation of the dust extraction system itself, including capture velocity at the hood, duct transport velocity (typically 18-22 m/s for coal dust to keep it entrained), filter face velocity at the baghouse (typically 1.0-1.5 m/min), and explosion mitigation (vented baghouse, rotary airlock at the dust hopper, earth bonding across all joints).
Coal dust is classified as a combustible dust under AS/NZS 60079 Zone 21 or 22 depending on the operating regime. Every duct accessory inside the dust handling envelope must carry an Ex tD certificate, and every duct joint must be bonded for static dissipation. The duct material is galvanized carbon steel 1.2-1.5 mm gauge to handle the abrasion of coal dust transport at 22 m/s for thirty years of plant life; SBKJ has supplied 1.5 mm galvanized spiral pipe from the SBTF-2020 tubeformer with full TIG-welded longitudinal seam for several coal mine and bulk handling clients.
3.5 Pulverised coal mill — explosion risk per AS/NZS 60079
Pulverised coal mills sit between the raw coal feed and the boiler. They grind raw lump coal into a fine powder (typically 70 percent through 75 micron) and convey the powder by primary air to the boiler burners. The mill itself is a hazardous environment: dry pulverised coal, hot primary air, and the possibility of mill ignition during start-up, shutdown or upset. AS/NZS 60079 Zone 21 applies inside the mill enclosure, and the surrounding mill compartment is typically Zone 22.
The HVAC scope here is the mill compartment ventilation — typically dedicated mechanical exhaust to a baghouse, sized for at least one air change per minute under fugitive emission scenarios. Duct material is 1.5 mm carbon steel with continuous welded seams, lagged for personnel protection where surface temperature exceeds 60 °C. Every duct accessory is Ex tD certified, every joint is earth-bonded, and the baghouse has explosion vents sized per the dust deflagration index Kst.
3.6 Air heater — the acid dew point line
The air heater sits in the flue gas path between the boiler exit and the precipitator or baghouse. It recovers heat from the outgoing flue gas to preheat the combustion air entering the boiler, lifting boiler efficiency by 3-5 percent. The flue gas enters the air heater at 320-380 °C and leaves at 130-160 °C. That 130-160 °C exit temperature is the critical engineering line in any coal-fired station — it is the acid dew point of sulphuric acid formed from SO2 in the flue gas combining with water vapour. Drop below it and the duct walls condense sulphuric acid; stay above it and the duct walls stay dry.
The implication for ductwork is that everywhere upstream of the air heater is dry hot flue gas — manage with carbon steel, often refractory-lined. Everywhere downstream of the air heater the duct walls may run wet with dilute sulphuric acid in service, and 316L stainless steel is mandatory. The transition zone at the air heater outlet itself is the most aggressive — the gas is cooling rapidly, droplets are forming on the duct walls, and the acid concentration is at its peak. 316L is the minimum spec; for high-sulphur coals, super-austenitic grades 904L or duplex 2205 are common in the air heater outlet duct, the precipitator inlet duct and the ID fan inlet duct.
3.7 FGD — flue gas desulfurisation, SO2 capture, limestone slurry
Flue gas desulfurisation (FGD) units capture SO2 from the flue gas. The dominant technology in Australia is wet limestone slurry absorption — the flue gas passes through a packed-bed or spray-tower absorber where a limestone slurry contacts the SO2 and converts it to calcium sulphate (gypsum) as a saleable by-product. The FGD outlet duct carries wet flue gas saturated with water vapour at about 50-55 °C, with residual SO2 below regulatory thresholds, residual chloride from the makeup water and trace sulphuric acid mist.
The wet stack environment is the most corrosive duct service in the station. 316L is the minimum; chloride bleed above 1,000 ppm forces an upgrade to super-austenitic 904L, duplex 2205 or 6 Moly grades. The duct seams must be continuously TIG-welded — lock-form seams are not acceptable because the wet acid attacks the seam interlock. SBKJ runs 316L through the SBAL-V auto duct line for rectangular FGD inlet ducts up to 1.5 mm and through the SBTF-2020 spiral tubeformer for circular wet-stack liners up to 1.5 mm. Every seam is TIG-welded under argon shield for a smooth weld bead that resists acid attack.
3.8 SCR — selective catalytic reduction, NOx control, ammonia injection
Selective catalytic reduction (SCR) reduces NOx in the flue gas to nitrogen and water by injecting anhydrous ammonia or aqueous ammonia over a vanadium-tungsten-titanium catalyst at 320-400 °C. The SCR catalyst bay sits between the boiler economiser exit and the air heater inlet, where the temperature is right for catalyst activity. Three HVAC sub-scopes are relevant: the ammonia receiving and storage area (AS/NZS 60079 hazardous zone, Ex-rated duct accessories), the ammonia injection grid plenum (316L stainless duct because of residual ammonia slip), and the catalyst bay access space (general ventilation with personnel protection from ammonia leaks).
The ammonia injection grid plenum is the highest-stress duct in the SCR system — it sits inside the flue gas path at 350 °C, carries an ammonia-air mixture at near-stoichiometric ratio to the NOx in the gas, and has to distribute the mixture uniformly across the catalyst face. 316L stainless 1.5 mm minimum, continuously TIG-welded, with internal flow distribution baffles that the duct fabricator integrates into the assembly. The ammonia receiving and storage area has separate ductwork — typically galvanized for the general make-up air and 316L for any local exhaust hood near the ammonia transfer pumps.
3.9 Baghouse — particulate capture
Downstream of the SCR (or upstream, depending on the configuration) sits the baghouse — a large filter house containing thousands of vertical filter bags through which the flue gas passes, capturing particulate at 99.9+ percent efficiency. The clean-side air on the outlet of the baghouse is essentially particulate-free but still carries residual SO2, NOx, water vapour, trace acid mist and any chloride from the makeup water. Material: 316L stainless 1.2-1.5 mm minimum. Seams: continuously TIG-welded. The bag changeout access has to be designed into the duct geometry from the start so that maintenance crews can rotate bags without disassembling the entire plenum.
The dirty-side ducting upstream of the baghouse is exposed to the full particulate load — fly ash at 5-15 g/Nm³ at the boiler exit, abrasive at duct elbows. Abrasion management uses elbow liners — typically ceramic or hard-faced steel inserts at the inner radius of every elbow — and gauge upgrade from 1.5 mm to 2.0 mm at high-velocity bends. SBKJ supplies 2.0 mm 316L for these high-wear sections through the SBAL-V auto duct line, with TIG-welded seams that survive the abrasion and the acid dew point.
3.10 Stack liner — the final flue path
The stack liner is the final flue gas path from the ID fan discharge to atmosphere. In a wet FGD installation the stack liner is wet — water condensate trickles down the inside wall continuously. 316L is the workhorse; for high chloride or high SO3 fuels, super-austenitic or fluoropolymer-lined steel takes over. The stack liner is usually a separate scope from the duct fabricator (procured as a complete steel liner from a specialist), but the transition spool from the ID fan discharge to the stack base is supplied as 316L spiral pipe — SBKJ has produced these spool pieces on the SBTF-2020 tubeformer up to 3 m diameter with continuous TIG seam welding.
4. Zone-by-zone HVAC reference — gas-fired station
Gas-fired stations divide into two architectures: open-cycle gas turbines (OCGT) used for peaking and reserve, and combined-cycle gas turbines (CCGT) used for mid-merit and baseload. The HVAC envelopes overlap with coal-fired stations but the contaminant profile is much cleaner and the fire risk is shifted to natural gas leakage rather than coal dust deflagration.
4.1 Gas turbine hall
A gas turbine sits inside a fully enclosed acoustic hood designed to suppress the turbine's high-frequency noise to below 85 dB(A) at the hall floor. Ventilation of the hood itself is dedicated — typically 60-80 air changes per hour with cooling air drawn from outside, blown across the turbine casing and the gas piping, and exhausted directly to atmosphere through the gas turbine exhaust gas duct or a dedicated cooling vent. The hood ventilation duct is carbon steel, welded seams, designed for the maximum gas turbine exhaust temperature in the event of a failure of the hood cooling fans.
Outside the acoustic hood, the turbine hall itself is ventilated like a coal-fired turbine hall — natural ventilation through roof monitors supplemented by mechanical exhaust, at 6-10 air changes per hour. Galvanized G300 ductwork is standard. The fuel gas receiving station is treated as a separate AS/NZS 60079 Zone 1 or Zone 2 hazardous area, with dedicated mechanical ventilation, Ex-rated duct accessories, and gas detectors that escalate the ventilation rate on detection.
4.2 Heat recovery steam generator (HRSG)
In a CCGT plant the gas turbine exhaust feeds a heat recovery steam generator (HRSG), which generates steam to drive a steam turbine. The HRSG is a vertical or horizontal heat exchanger with finned tube bundles in a flue gas path that exits to a stack. The flue gas leaving an HRSG is much cleaner than coal flue gas — no fly ash, very low SO2 because natural gas is essentially sulphur-free, NOx managed by SCR if local emissions limits require it. The HRSG enclosure is ventilated by carbon steel ductwork with welded seams; the SCR ammonia injection (if fitted) follows the same 316L specification as for a coal-fired SCR.
4.3 Combined-cycle commissioning — NFPA 56 application
During commissioning of a new CCGT plant the gas turbine fuel piping has to be cleaned of construction debris before first fire. NFPA 56 prescribes the cleaning sequence — typically a high-velocity air or steam blow through the piping into a temporary exhaust line vented safely outside the gas turbine hall. The duct fabricator's role in this commissioning scope is to supply temporary heavy-gauge carbon steel duct sections with bolted flanges, sized for the cleaning blow rate, and dismantled after commissioning. These are usually 6-12 mm wall thickness because the dynamic pressure during a steam blow is severe.
5. Decommissioning HVAC — what changes when the station retires
A coal station that runs for forty years has accumulated asbestos lagging on steam pipes and turbine casings, lead paint on steel framework, residual fly ash inside every duct, sometimes mercury contamination from the coal feedstock, sometimes polychlorinated biphenyl (PCB) in old transformer oil. Decommissioning has to remove all of that safely before the steel can be cut up for scrap and the concrete can be crushed for recycle.
5.1 Asbestos removal
Asbestos lagging is the dominant hazard in any pre-1990 coal-fired station. Removal proceeds zone by zone under controlled conditions — typically a fully enclosed negative-pressure work area sealed with polyethylene sheet, with mechanical exhaust to a HEPA-filtered scrubber, decontamination airlock, and continuous air monitoring. The HVAC scope is temporary: temporary fans, temporary ductwork, temporary HEPA filter banks. The duct material is light-gauge galvanized or aluminium because the ductwork is dismantled and disposed of after the asbestos campaign. Spiral pipe from the SBTF-2020 tubeformer is common because spiral pipe is rigid, lightweight and easy to install in a temporary configuration.
The exhaust rate is sized to keep the enclosure at -5 Pa to -10 Pa relative to the surrounding building, so that any leak through the polyethylene sheet pulls clean air into the work area, not contaminated air out. Typical capture rates are 4-8 air changes per hour for friable lagging removal. Every joint in the temporary duct system is taped, every fan motor is Ex-rated if there is any residual coal dust risk, and every HEPA filter is bagged out for disposal as asbestos waste.
5.2 Lead paint stripping
Old steel framework in pre-1980 stations was painted with lead-based primer. Demolition cutting and grinding of that steel releases lead dust at hazardous concentrations. The HVAC scope is similar to asbestos: temporary negative-pressure enclosures, mechanical exhaust to HEPA filtration, continuous personal monitoring. The duct material is again light-gauge galvanized or aluminium spiral, sized for 4-8 air changes per hour, dismantled and disposed of after the lead campaign. SBKJ has supplied temporary spiral duct kits to demolition specialists on Australian power station decommissioning projects in 0.5-0.8 mm galvanized through the SBTF-2020 tubeformer.
5.3 General demolition dust
After the hazardous materials are out, the structural demolition releases concrete dust, steel cutting fume, refractory dust from boiler casings and residual coal dust from inside the boiler tubes. The temporary HVAC scope at this phase is large-volume dust suppression — water misting at the cutting front supplemented by mechanical exhaust to a coarse cyclone and bag filter assembly. Duct material is galvanized spiral pipe in 0.8-1.0 mm gauge, sized for the demolition contractor's bag filter capacity.
5.4 Cost ratio — decommissioning HVAC as a share of total decommissioning
Typical decommissioning cost benchmarks for a 1,000-2,000 MW Australian coal station run AUD 100-300 million depending on site complexity, residual contamination and the depth of site rehabilitation. Of that total, temporary HVAC for asbestos, lead and demolition dust typically accounts for 3-6 percent of the total — AUD 3-18 million across the campaign. That is enough volume to justify dedicated fabrication runs of temporary spiral pipe rather than ad-hoc procurement, and several Australian decommissioning specialists now run dedicated SBKJ spiral tubeformers in their own shops for this scope.
6. The Australian coal-fired fleet — operator-by-operator status
The thirteen coal-fired stations below carry the bulk of Australia's remaining thermal capacity. Each entry is the status as of mid-2026 against the AEMO Integrated System Plan and the most recent operator announcements; closure dates are subject to revision under the Capacity Investment Scheme and the AEMO Reliability Forecast.
Eraring NSW — 2,880 MW, Origin Energy
Eraring on Lake Macquarie is Australia's largest single power station, with four 720 MW black-coal units commissioned in the early 1980s. Origin Energy announced closure for August 2025 but subsequently extended to August 2027 under a commercial agreement with the NSW Government to bridge the renewable rollout. Origin is staging a multi-stage BESS on the site: a first 460 MW / 1,073 MWh stage is operational and a second 240 MW / 1,727 MWh expansion is in commissioning, bringing the planned aggregate to 2,800 MWh on the existing footprint. The HVAC scope across the transition runs three streams in parallel: operating maintenance HVAC for the ageing coal units, temporary decommissioning HVAC for the eventual deconstruction, and new-build battery thermal management HVAC for the BESS halls.
Vales Point NSW — 1,320 MW, Delta Electricity
Vales Point on Lake Macquarie is a 1980s-vintage 2 × 660 MW station owned by Delta Electricity. The current closure date sits at 2033 under the most recent operator and AEMO assessments, but Delta has flagged that the closure may be brought forward depending on coal supply economics. Vales Point's coal handling area is one of the most extensive in NSW and the dust extraction baghouse system is in regular rehabilitation — a continuing source of dust collection duct fabrication work for the regional supply chain.
Mt Piper NSW — 1,400 MW, EnergyAustralia
Mt Piper near Lithgow is a 2 × 700 MW black-coal station owned by EnergyAustralia, commissioned in the early 1990s. The closure date sits at 2040 in the current AEMO ISP, making Mt Piper one of the longer-running thermal assets in the NSW fleet. EnergyAustralia has flagged Mt Piper as a candidate for synchronous condenser repurposing post-closure to provide grid inertia and short-circuit capacity to the western NSW transmission system. The HVAC scope at Mt Piper has been progressively upgraded since 2018, with FGD considered but not yet committed.
Bayswater NSW — 2,640 MW, AGL
Bayswater in the Hunter Valley is a 4 × 660 MW black-coal station owned by AGL, commissioned in the mid-1980s. Closure is scheduled for 2033 under the most recent AGL announcements, aligned with the AEMO ISP. AGL has not formally committed to a BESS repurposing at Bayswater on the scale of Liddell next door, but the site's 500 kV switchyard makes it a natural candidate. The HVAC envelope at Bayswater includes a particularly large turbine hall — four 660 MW units share a continuous hall about 280 m long, ventilated at 1.5 million m³/h in summer.
Loy Yang A VIC — 2,210 MW, AGL
Loy Yang A in the Latrobe Valley is a 4 × 560 MW brown-coal station owned by AGL, commissioned in the mid to late 1980s. Closure is currently scheduled for 2035 in the AEMO ISP. Brown coal is high-moisture, high-ash and low in calorific value, which means the HVAC envelope at Loy Yang A is denser than at the equivalent NSW black-coal station — the coal mills are larger, the air heater duct paths are longer, and the FGD scope (if committed) would be substantial. AGL is evaluating BESS and pumped hydro options on the Latrobe Valley sites post-closure.
Loy Yang B VIC — 1,026 MW, AlintaEnergy
Loy Yang B next door to Loy Yang A is a 2 × 530 MW brown-coal station owned by AlintaEnergy, commissioned in the early 1990s. Closure is scheduled for 2047 in the current ISP, making it the longest-running thermal station in the Australian fleet under the present plan. AlintaEnergy has signalled progressive HVAC upgrades through the 2030s to keep the plant operating reliably to its closure date.
Yallourn VIC — 1,480 MW, EnergyAustralia
Yallourn in the Latrobe Valley is a 4 × 370 MW brown-coal station owned by EnergyAustralia, commissioned across the 1970s and early 1980s. EnergyAustralia announced closure for mid-2028. Decommissioning planning is well advanced and the temporary HVAC scope for asbestos and lead campaigns is being scoped through 2026-2027. The site is being evaluated for grid-scale BESS deployment in conjunction with the existing 500 kV switchyard.
Stanwell QLD — 1,460 MW, Stanwell Corporation
Stanwell near Rockhampton is a 4 × 365 MW black-coal station owned by Stanwell Corporation, commissioned in the 1990s. Closure is scheduled for 2046 under the current ISP. Stanwell is a relatively young thermal asset and its HVAC envelope is in routine maintenance — no major decommissioning planning is underway.
Tarong QLD — 1,843 MW, Stanwell Corporation
Tarong near Nanango is a 4 × 350 MW plus 1 × 443 MW (Tarong North) black-coal complex owned by Stanwell. The closure dates for the Tarong units are not yet firmly committed in the ISP but the major Tarong units are expected to retire through the late 2030s. Stanwell has flagged Tarong as a long-term grid stability site, with potential synchronous condenser conversion of the existing generators after coal retirement.
Callide QLD — 1,720 MW, CS Energy
Callide near Biloela is a complex of black-coal units owned by CS Energy. The May 2021 explosion at Callide C4 took a 420 MW unit offline for an extended outage and the unit returned to service progressively through 2023-2024. The HVAC scope for the Callide rehabilitation included substantial replacement of duct runs that were damaged in the explosion. CS Energy has not yet formally committed a closure date for the remaining Callide units; AEMO modelling treats Callide as remaining in service through the early 2030s.
Gladstone QLD — 1,680 MW, NRG / Stanwell
Gladstone in Central Queensland is a 6 × 280 MW black-coal station historically operated by NRG with Stanwell joint ownership. Closure is committed for 2029, making Gladstone the next major Queensland coal closure after the imminent retirements in NSW and Victoria. Decommissioning planning is now under way and temporary HVAC requirements through 2029-2032 are substantial.
Kogan Creek QLD — 744 MW, CS Energy
Kogan Creek near Chinchilla is a single 744 MW supercritical black-coal unit owned by CS Energy, commissioned in 2007 — the youngest coal-fired generator in the National Electricity Market. Its closure date is not yet committed; AEMO modelling assumes Kogan Creek operates into the late 2040s.
Liddell NSW — 1,680 MW, AGL (closed 2023)
Liddell in the Hunter Valley closed in April 2023 after 52 years of operation. AGL is now deconstructing the site and constructing a 500 MW / 2,000 MWh BESS on the cleared footprint, with the existing 330 kV / 500 kV switchyard providing the grid connection. Decommissioning HVAC at Liddell across 2023-2027 includes asbestos lagging removal from the steam piping and turbine casings, lead paint stripping of the structural steel, and general demolition dust control as the boilers and turbine halls come down. Australian decommissioning specialists Downer, UGL and Monadelphous are active on the Liddell site.
Hazelwood VIC — 1,600 MW, ENGIE (closed 2017)
Hazelwood in the Latrobe Valley closed in March 2017 after 53 years of operation. The site is in long-term rehabilitation including the Hazelwood mine fire remediation. HVAC scope at Hazelwood across the 2017-2030 rehabilitation period covers asbestos removal from the eight 200 MW units, lead paint stripping, residual fly ash management, and the mine void rehabilitation including dust suppression at the working face.
Northern SA — 520 MW (closed 2016)
Northern Power Station at Port Augusta closed in May 2016. The site has been progressively rehabilitated and is the subject of multiple proposals for renewable replacement including concentrated solar thermal and BESS.
Playford SA — 240 MW (closed 2015)
Playford B at Port Augusta closed in 2015 after 50 years of operation. The site rehabilitation is ongoing.
7. The Australian gas-fired fleet — peakers and CCGTs
Gas-fired stations are newer than the coal fleet and many are expected to continue operating through 2050 as peakers and firming capacity behind the renewable rollout. The HVAC envelopes are smaller per MW than for coal but the hazardous-area scope around the fuel gas receiving stations is more extensive.
Tallawarra NSW — 420 MW (Tallawarra A), 320 MW (Tallawarra B)
Tallawarra A is a CCGT on Lake Illawarra commissioned in 2008. Tallawarra B is a hydrogen-blend OCGT being commissioned to provide firming capacity. The HVAC scope for Tallawarra B includes hydrogen-receiving station ventilation under AS/NZS 60079, with stainless steel exhaust ductwork for any potential hydrogen vent paths.
Pelican Point SA — 478 MW
Pelican Point in Adelaide is a CCGT commissioned in 2000-2001. The plant operates as a baseload-to-mid-merit asset on natural gas with established HVAC systems and routine maintenance scope.
Mortlake VIC — 566 MW (Mortlake A)
Mortlake in western Victoria is an OCGT pair commissioned in 2012. The station is operated by Origin Energy and is expected to operate through 2050 as a peaking and firming asset.
Newport VIC — 510 MW
Newport in Melbourne's western suburbs is a single-unit gas-fired station commissioned in 1981. The plant is owned by EnergyAustralia and has been continuously operational since its commissioning, with progressive HVAC upgrades over its life.
Torrens Island SA — 800 MW (decommissioning)
Torrens Island B in Adelaide was a gas-fired plant owned by AGL, commissioned in the late 1970s and progressively retired through 2022-2024. The site is being progressively repurposed including a 250 MW / 250 MWh BESS commissioned in 2021 on the existing footprint.
Kwinana WA — 240 MW
Kwinana in Perth is a gas-fired plant owned by Synergy, commissioned through the 2000s as a replacement for retired coal units. The HVAC envelope is standard CCGT scope.
8. Coal-to-BESS and coal-to-syncon repurposing — the HVAC scope change
A retired coal station has three irreplaceable assets that no greenfield BESS site has: an established 330 kV or 500 kV grid connection, an existing 100-500 hectare cleared and zoned industrial footprint, and access to large volumes of cooling water from the existing condenser intake or cooling tower system. Those three assets make former coal stations the highest-value candidate locations for grid-scale battery energy storage systems and synchronous condensers — both of which are central to the AEMO ISP transition.
8.1 BESS thermal management
A grid-scale BESS using lithium-iron-phosphate (LFP) or lithium nickel manganese cobalt (NMC) chemistry has tight thermal management requirements. Cell temperature must sit between 23 and 27 °C for optimum cycle life, and humidity must sit below 50 percent relative humidity to prevent condensation on the busbars. Battery enclosures are typically conditioned by dedicated package chillers feeding a duct network inside each enclosure, with redundant N+1 chiller capacity and a dedicated chilled-water buffer tank for thermal runaway scenarios.
The duct material inside a battery enclosure is conventional galvanized steel — the conditioned space is clean and dry, with no acid or particulate load. SBKJ has supplied SBAL-V auto duct line output in 0.6-0.8 mm galvanized for battery enclosure conditioning ducts on Australian BESS projects, with TDF flanges and EPDM gaskets for the airtight low-leakage construction required by AS/NZS 4254 Class A. The auxiliary cooling pad outside the enclosures uses larger galvanized rectangular ducts for chilled-water air handler discharge, sized for 4-6 °C delta T between supply and return.
8.2 Synchronous condenser HVAC
A synchronous condenser is a synchronous machine that runs without mechanical load — its purpose is to provide reactive power, short-circuit current and rotational inertia to the grid. Several retired coal-fired generators are candidates for synchronous condenser conversion: remove the steam turbine, retain the generator, add a starting motor, and operate the generator as a syncon. The HVAC scope for a syncon is essentially the generator hall HVAC of the original coal plant — same hydrogen cooling system, same lubrication oil cooling, same battery room — minus the steam turbine and boiler envelopes that get demolished or repurposed.
The advantage of syncon repurposing over greenfield syncon construction is the avoided cost of the generator itself. The disadvantage is that the generator HVAC has to be rehabilitated after a generation of coal-station service — duct corrosion from fly ash deposits, asbestos lagging on adjacent piping, and the general accumulation of grime — and the rehabilitation HVAC scope is substantial.
8.3 Eraring BESS — the headline case study
Origin Energy's Eraring BESS is the headline case study for Australian coal-to-BESS conversion. The first 460 MW / 1,073 MWh stage was commissioned and a second 240 MW / 1,727 MWh expansion is in commissioning, with a planned aggregate of 2,800 MWh sitting on the existing Eraring footprint. The BESS uses LFP chemistry in containerised enclosures arranged on a former coal storage yard. The HVAC envelope across the BESS is dedicated chillers per battery row, redundant package air handlers, and a stainless steel exhaust duct network for thermal runaway venting.
8.4 Liddell BESS — the deconstruction-and-replace case study
AGL's Liddell BESS sits on a fully cleared site after deconstruction of the four 500 MW coal units. The 500 MW / 2,000 MWh BESS uses LFP chemistry with grid connection through the existing 500 kV switchyard. The HVAC scope is greenfield — package chillers, galvanized duct enclosures, AS 1668 compliance — sitting on a brownfield footprint with the residual decommissioning HVAC for asbestos and lead campaigns running in parallel.
9. Asset Stewardship and Resilience — ASRES criteria
The Australian thermal-fleet operators apply Asset Stewardship and Resilience (ASRES) criteria to every continuing-operation HVAC capital expenditure. ASRES is an internal framework adopted across AGL, Origin Energy, EnergyAustralia, CS Energy, Stanwell, Delta Electricity, NRG and AlintaEnergy that assesses every proposed HVAC retrofit against: residual asset life (against the ISP closure date), safety risk reduction, environmental performance improvement, condition-based maintenance signal quality and capital efficiency per MW of residual capacity served.
For HVAC retrofits in the last 5-10 years of a station's life ASRES drives a strong preference for low-capital, high-reliability fabrication. The duct fabricator's role is to supply ductwork that lasts to closure but does not cost the operator a full 30-year capital depreciation. Practical implication: SBKJ has supplied 316L stainless duct sections for last-decade FGD outlet rehabilitation projects, with TIG-welded seams sized to the residual operating life rather than to a full 30-year service envelope. The same machine that produces 316L for new-build CCGT FGD work also produces shorter-life duct for closure-bound coal plants.
10. The EPC supply chain — who does what
The Australian thermal-fleet EPC supply chain has consolidated into a small number of specialists. Each of these contractors carries internal HVAC subcontract scope and engages duct fabricators on extended panel arrangements.
Worley
Worley is the dominant engineering services firm on the Australian thermal fleet — design, construction supervision, commissioning and shutdown engineering across coal and gas stations. Worley's HVAC scope includes detailed design for new build, life-extension HVAC upgrades, and decommissioning HVAC planning. Duct fabrication is sourced through panel agreements with regional fabricators.
UGL
UGL is a major construction and maintenance contractor on the thermal fleet, with strong positions in NSW and Queensland coal stations. UGL operates planned outage maintenance contracts at multiple stations and engages duct fabricators through call-off agreements for outage HVAC work.
Downer
Downer is a major rail, civil and engineering services firm with substantial power-sector exposure, including the Liddell deconstruction. Downer's HVAC scope on decommissioning projects covers temporary ventilation for asbestos and lead campaigns and the demolition-phase dust management.
Monadelphous
Monadelphous is a specialist mechanical and electrical construction firm with significant decommissioning capability. Monadelphous has been active on Latrobe Valley brown-coal decommissioning and on Hunter Valley deconstruction work, with internal HVAC and dust suppression scope across the asbestos, lead and demolition phases.
11. Material selection summary — galvanized vs 316L vs refractory-lined
The material selection across a thermal station boils down to three families with clear boundaries:
Galvanized G300 carbon steel
Service envelope: outside-air supply, conditioned office and control building, clean-side air below 200 °C, no acid or particulate load. Standard gauges 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm to AS/NZS 4254. Joining: TDF/TDC flanges, Pittsburgh or snap-lock seams. Lifespan: 30-40 years in benign service, 12-36 months downstream of any acid dew point. SBKJ production: SBAL-V auto duct line for rectangular, SBTF-2020 spiral tubeformer for circular.
316L stainless steel
Service envelope: any duct downstream of air heater, FGD, SCR, baghouse or wet stack. Standard gauges 1.0 mm, 1.2 mm, 1.5 mm and 2.0 mm at high-wear sections. Joining: continuous TIG-welded seam under argon shield, companion-flanged with full-penetration welded collar, EPDM or PTFE gasket. Lifespan: 25-30 years in wet acid service. SBKJ production: SBAL-V auto duct line in stainless configuration, SBTF-2020 spiral tubeformer in stainless, TIG seam welder for every joint. For high-chloride or high-SO3 fuels, super-austenitic grades 904L, duplex 2205 or 6 Moly substitute for 316L.
Refractory-lined carbon steel
Service envelope: any duct upstream of the air heater where flue gas temperature exceeds 400 °C and metal temperatures exceed the service envelope of stainless. Typically 6-12 mm carbon steel outer shell with 50-150 mm refractory castable or refractory brick lining on the gas side. Joining: continuously welded butt seams, no flange joints in the gas path. Lifespan: 20-25 years on the carbon shell, refractory rebuild every 8-12 years. SBKJ does not supply refractory-lined steel — this is a specialist boiler-maker scope.
12. SBKJ machine configuration for thermal-fleet work
Three SBKJ machine configurations cover the bulk of the duct fabrication scope across an Australian thermal-fleet HVAC project, whether new build, retrofit, decommissioning or BESS repurposing.
SBAL-V auto duct line in stainless 316L configuration
The SBAL-V auto duct line is SBKJ's flagship rectangular duct fabrication system, producing finished rectangular ducts up to 1.5 m × 1.5 m cross-section with integrated TDF/TDC flange forming and seam locking on a single line. In stainless 316L configuration, the SBAL-V handles 1.0-1.5 mm 316L coil with TIG seam welding integrated into the line. Output rates are 6-10 m of finished duct per minute depending on size and configuration. For an FGD outlet duct retrofit at a coal-fired station, the SBAL-V in stainless configuration delivers the full duct run including flanges in a single integrated production cycle.
SBTF-2020 spiral tubeformer in stainless
The SBTF-2020 spiral tubeformer produces continuous spiral pipe from 80 mm to 2,000 mm diameter, in galvanized or stainless steel from 0.5 mm to 1.5 mm gauge. With integrated TIG seam welding, the SBTF-2020 produces stainless spiral pipe for FGD inlet ducting, wet stack liner transition spools, SCR ammonia injection grid plenum and battery enclosure stainless return ducting on a BESS retrofit. Output rates are 12-18 m of finished pipe per minute depending on diameter and gauge.
TIG seam welder
SBKJ's TIG seam welder operates as a stand-alone station for any longitudinal seam that has to be continuously welded — typically the longitudinal seam of stainless spiral pipe, the seam of welded rectangular duct, and any custom transition spool fabricated outside the auto line. Argon shielding gas at 12-15 L/min, root pass at 80-120 A, cap pass at 120-160 A, with automated travel speed control for consistent bead geometry. The TIG seam welder is essential for the wet-service stainless duct that survives FGD and stack-liner environments.
13. Procurement guidance — what to specify when
The procurement of HVAC ductwork for an Australian thermal-fleet project — whether new build, life extension, decommissioning or BESS repurposing — follows a different rhythm from a commercial building project. The duct runs are longer, the material specifications are tighter, the certification chain is denser, and the operating life is longer. The guidance below covers the highest-leverage procurement decisions.
13.1 Specify by zone, not by aggregate quantity
Avoid the temptation to bundle the entire station's duct procurement into a single tender. Each zone has its own material, gauge and seam specification, and each zone has its own audit trail back to AS 1668, AS/NZS 60079, NFPA 850 or other code references. Tender each zone separately, against its own material datasheet and its own pressure class, and let the fabricator return separate quotations against each zone. This makes apples-to-apples comparison straightforward across multiple fabricators.
13.2 Demand material certificates with every shipment
316L coil from different mills can vary in chloride pitting resistance equivalent number (PREN) within the standard tolerance. Demand mill test certificates with every shipment of stainless duct, traceable from the coil heat number through the duct piece marking. SBKJ supplies mill certificates as standard with every stainless duct shipment, traceable on the duct piece marking.
13.3 Require a Factory Acceptance Test on every auto duct line shipment
Even for routine galvanized duct, a Factory Acceptance Test before shipment catches manufacturing defects that would otherwise turn into commissioning-day rework. The FAT covers a sample of finished ducts produced on the buyer's coil specification, dimensional verification, pressure leakage test to AS/NZS 4254 Class A or B as required, and seam integrity inspection. The cost of a FAT is recovered many times over by the avoided rework on a brownfield power station site.
13.4 Lock in a 10-year spare-parts continuity guarantee
HVAC duct machinery for power station fabrication is a 15-20 year capital asset on the fabricator's side, but the spare-parts continuity matters even on the buyer's side because retrofit fabrication continues for 15-20 years after first installation. Lock in a 10-year spare-parts continuity guarantee in writing with every machine purchase, and verify the supplier's parts-stocking arrangement in their service region.
13.5 Plan the decommissioning HVAC scope at the same time as the new build
For new combined-cycle gas plants and BESS retrofits at former coal sites, plan the decommissioning HVAC scope in parallel with the new-build scope. Asbestos removal, lead paint stripping and demolition dust control campaigns run on different schedules and use different fabrication standards from new-build HVAC. Engaging the same duct fabricator on the new-build and the decommissioning streams in parallel keeps the audit trail consistent and the project schedules aligned.
14. The AEMO Integrated System Plan — what it means for the duct fabricator
The AEMO Integrated System Plan is the 30-year roadmap for the National Electricity Market, updated every two years. The 2024 ISP set out a pathway for orderly retirement of the coal fleet, deployment of 30+ GW of utility-scale renewables, 10+ GW of storage, and the firming gas-fired peaker capacity required to maintain reliability through the transition. From the duct fabricator's perspective the ISP creates four concurrent and overlapping streams of work through 2035 and beyond:
- Operating-life HVAC maintenance on the remaining coal fleet through to each station's closure date — FGD outlet rehabilitation, baghouse plenum replacement, control building HVAC upgrade, coal handling dust extraction rehabilitation. Stainless 316L for wet service, galvanized for clean-side.
- Decommissioning HVAC on stations entering deconstruction — temporary HVAC for asbestos, lead and demolition dust, light-gauge galvanized or aluminium spiral pipe, disposable construction.
- New-build CCGT HVAC on the firming gas peakers that fill the gap between renewables and load — combined-cycle gas turbines at sites including extended Tallawarra, Newport, Mortlake, with full HVAC envelope including SCR and HRSG ductwork.
- BESS and syncon repurposing HVAC on former coal sites — Liddell BESS, Eraring BESS, future BESS at Yallourn, Bayswater and Mt Piper. Galvanized duct for the conditioned battery enclosures, stainless for thermal runaway exhaust, AS/NZS 4254 Class A leakage construction.
SBKJ machinery serves all four streams. The SBAL-V auto duct line in switchable galvanized and stainless configuration covers operating maintenance, new-build CCGT and BESS retrofit. The SBTF-2020 spiral tubeformer in galvanized handles decommissioning temporary duct kits, and in stainless handles FGD inlet and wet stack liner transition spools. The TIG seam welder backs up every wet-service stainless run.
15. The SBKJ position — Australian thermal-fleet HVAC scope
SBKJ Group operates from Box Hill North, Victoria, with extended supply chain coverage across the Latrobe Valley, Hunter Valley and Central Queensland thermal corridors. Our engineering team has commissioned duct fabrication machinery on Australian power station and industrial projects since the mid-1990s, with 5,000+ machines installed across 100+ countries and a continuing focus on the Australian thermal-to-renewable transition. Three machine families cover the bulk of the thermal-fleet HVAC scope:
- SBAL-V auto duct line in galvanized and switchable stainless configuration, rectangular duct to 1.5 m × 1.5 m, TDF/TDC flanges integrated, TIG seam welding for wet-service stainless. SBKJ machine catalogue.
- SBTF-2020 spiral tubeformer in galvanized and stainless, 80 mm to 2,000 mm diameter, 0.5-1.5 mm gauge, integrated TIG seam welding for stainless wet-service spiral.
- TIG seam welder as a stand-alone station for any longitudinal seam, automated argon-shielded with travel-speed control.
The same machinery serves the new-build CCGT scope, the operating-life maintenance scope on the remaining coal fleet, the decommissioning temporary-HVAC scope on retiring stations, and the BESS and syncon repurposing scope on former coal sites. Single-supplier traceability across all four streams simplifies the audit trail for the asset owner and the EPC contractor.
Talk to an SBKJ engineer about thermal-fleet HVAC fabrication →
FAQ
Why does galvanized duct fail downstream of the air heater in a coal-fired station?
Coal flue gas contains SO2 and NOx that condense as sulphuric and nitric acid wherever the gas drops below the acid dew point (130-150 °C). Galvanized zinc coating is consumed within 12-36 months under that acid attack, while fly ash abrasion accelerates substrate wear. SBKJ specifies 316L stainless downstream of the air heater, FGD, SCR catalyst bed and baghouse.
What is the ventilation rate for a 500 MW turbine hall?
Australian turbine halls in the 200-500 MW range design for 8-12 air changes per hour at summer ambient. A 500 MW generator typically rejects 1-2 percent of its electrical output as parasitic heat, so 5-10 MW of sensible heat plus solar gain drives engineered air volumes of 250,000-450,000 L/s.
Which Australian coal stations are closing between now and 2035?
Eraring NSW by August 2027, Yallourn VIC mid-2028, Gladstone QLD 2029, Bayswater NSW by 2033, Loy Yang A VIC by 2035, Mt Piper NSW by 2040, Stanwell QLD by 2046, Loy Yang B VIC by 2047. Liddell NSW closed in April 2023 and is in active deconstruction.
What HVAC standards apply across a thermal station?
AS 1668.1 fire and smoke, AS 1668.2 indoor air quality, AS 1668.4 natural ventilation, AS/NZS 60079 hazardous areas, AS 5034 battery rooms, IEEE 484 stationary battery installation, NFPA 850 fire protection, NFPA 56 gas piping cleaning. Plus AS 4024 machinery safety, AS/NZS 4865 combustible dust extraction, AS/NZS 4254 ductwork gauge and pressure class.
Can a retired coal site be repurposed as a BESS or synchronous condenser?
Yes — the existing high-voltage switchyard, water rights, cleared site footprint and grid connection make former coal sites the highest-value BESS and syncon locations. Origin's Eraring BESS is staging to 2,800 MWh, AGL's Liddell BESS is 500 MW / 2,000 MWh on the cleared coal footprint. HVAC scope changes from boiler-house heat rejection to lithium battery thermal management at 23-27 °C and below 50 percent RH.
What stainless grade does SBKJ recommend downstream of FGD and SCR?
316L (1.4404 / EN UNS S31603) is the workhorse for FGD absorber outlet, wet stack liner, SCR ammonia injection grid plenum and baghouse clean-gas side. For wet FGD with chloride bleed above 1,000 ppm, super-austenitic grades 904L or duplex 2205 are specified. SBKJ runs 316L through the SBAL-V auto duct line up to 1.5 mm and through the SBTF-2020 spiral tubeformer up to 1.5 mm.
