Aquaculture, Salmon Farming, Fish Processing, Seafood Cannery, Abalone, Oyster and Prawn HVAC Duct Guide

Why aquaculture and seafood processing HVAC is its own engineering category

Australian aquaculture and seafood processing represents the most chloride-aggressive, multi-zone HVAC envelope in the country's food manufacturing sector. A modern integrated salmon operation runs eighteen to twenty distinct climatic envelopes inside one footprint — freshwater hatchery and recirculating aquaculture system at 8 to 14 degrees Celsius with controlled CO2 and ammonia scrubbing, smolt transfer hall, marine grow-out support infrastructure, harvest receival at chilled brine immersion, gutting and heading floor at 4 to 8 degrees Celsius with continuous saltwater wash-down, blood and offal collection at minus 15 Pascal pressurisation, fillet trim and portion at 4 to 6 degrees Celsius with HEPA-filtered supply, smoking kiln at 18 to 90 degrees Celsius across cold-smoke and hot-smoke product lines, IQF tunnel freezer at minus 30 to minus 40 degrees Celsius with 3 to 6 metres per second air velocity across the product, ammonia compressor plant room at AS/NZS 60079 Class I Zone 2 classification, retort hall at 115 to 125 degrees Celsius saturated steam atmosphere for canned product, the abalone propagation hall with micro-algae production tanks releasing dimethyl sulphide, the oyster shucking bench with ozone wash hall ventilation, and the prawn snap-freeze tunnel with the dual demand of head-on shell-on premium product and IQF peeled product. Each envelope demands its own duct material specification, sealing class, pressurisation differential and sanitation regime. Each is governed by a different combination of AS 4696, AS/NZS 4674, FSANZ 4.2.1, AS/NZS 60079, AS/NZS 1668.2 and the AQIS export licence compliance programme. And every duct surface above an open product zone is audit-visible — an ATP swab or a Listeria monocytogenes finding on a tea-stained or pitted duct can suspend an AQIS export licence in twenty-four hours.

SBKJ Group has supplied auto duct production lines, spiral tubeformers, stitchwelders, plasma cutters and longitudinal seam welders into the Australian aquaculture and seafood processing sector since the early 2010s. Our engineers from the Box Hill North VIC office have walked the Tassal Huonville processing floor, the Petuna Devonport ocean trout line, the Yumbah Narrawong abalone hatchery, the Australian Prawn Farms Yamba snap-freeze tunnel, the Clean Seas Port Lincoln Yellowtail Kingfish gutting line and the Coffin Bay oyster opening hall. We have seen what fails in the Tasmanian coastal salt-aerosol environment, what stands up to a fifteen-year sanitation cycle of chlorinated foam plus peracetic acid plus continuous saltwater wash-down, and what the AQIS auditor flags first when an export plant is at risk of suspension. This guide is written against that field experience. Pricing is held back here because pricing is meaningful only in the context of a specific facility brief; talk to an SBKJ engineer for an itemised landed-cost worksheet that ties scope to scope.

The Australian aquaculture and seafood processing sector — operators, species and geography

Before specifying HVAC ductwork for any aquaculture or seafood facility the engineering team has to know the species, the operator, the production scale, the export licence portfolio and the regulatory envelope. Australia is the largest wild-caught and farmed salmon producer in the southern hemisphere, the dominant abalone producer in the Pacific, a major prawn producer through both wild capture and farmed vannamei production, a significant oyster producer with three commercial species, and an emerging Yellowtail Kingfish exporter to Japan and Korea. The sector is concentrated across roughly thirty large integrated operators and several hundred smaller specialty operations.

Atlantic salmon and ocean trout — Tassal, Huon and Petuna

Tassal Group is the largest Atlantic salmon producer in Australia, operating marine grow-out pens across Macquarie Harbour, the D'Entrecasteaux Channel, Storm Bay and Tasman Peninsula in Tasmania. Tassal acquired Huon Aquaculture in 2022, consolidating the two largest Tasmanian salmon producers, and subsequently became part of the Cooke Inc global aquaculture group. The Tassal processing footprint includes the primary processing facility at Huonville TAS (the largest single salmon processing line in Australia by throughput), the Margate plant for value-added product, the Tassal Triabunna land-based recirculating aquaculture system for smolt production, and the Don Smallgoods sister operation at Castlemaine VIC for hot-smoked salmon and salami-style cured product. Tassal supplies the major supermarket retail chains, the food service sector, the QSR chains and a substantial export programme into Japan, Hong Kong, Singapore and the Middle East.

Huon Aquaculture — founded by the Bender family and headquartered at Parramatta Creek TAS — operates marine grow-out pens at Macquarie Harbour, Hideaway Bay and the Tasman Peninsula. Huon's primary processing is at the Parramatta Creek facility with secondary operations at Whale Point and Forest Home. The Huon Aquaculture brand continues under the Tassal ownership umbrella with maintained brand independence in the retail and food service channels. Huon was an early Australian adopter of in-pond cleaner fish (wrasse and lumpfish) for amoebic gill disease management and built the most engineering-intensive Tasmanian salmon hatchery at Forest Home.

Petuna Seafoods at Devonport and Cressy TAS is the third major Tasmanian Atlantic salmon producer and the largest Australian ocean trout producer. Petuna's marine grow-out is concentrated in Macquarie Harbour and adjacent waters, with primary processing at the Devonport plant. Petuna is privately owned, family operated, and runs both an Atlantic salmon and an ocean trout (sea-run rainbow trout) production line in parallel — ocean trout is a higher-value premium product line targeting the Asian sashimi market and the Australian high-end retail and restaurant trade. The Cressy hatchery is a freshwater recirculating aquaculture system supplying smolt to both the Atlantic salmon and ocean trout grow-out operations.

Sealord Australia — the Australian arm of the New Zealand-headquartered Sealord Group, ultimately owned by Nippon Suisan and the Maori-owned Moana New Zealand — operates the largest mackerel and tuna processing capacity in Australia from Port Lincoln SA and supplies the canned seafood and frozen seafood retail and food service channels. Sealord operates Spencer Gulf wild prawn processing alongside the canned and frozen finfish capacity. The Port Lincoln SA cluster is the densest seafood processing concentration in Australia outside Tasmania.

Abalone — Yumbah, Australian Bight Abalone and the wild fishery

Australian abalone production combines a substantial wild fishery (greenlip, blacklip and Roe's abalone harvested under tightly managed state fishery licences) with a fast-growing farmed sector based on land-based pump-ashore systems. Yumbah Aquaculture is the largest farmed abalone producer in Australia, operating land-based pump-ashore farms at Narrawong VIC (the original Yumbah site established in the early 2000s), Smithton TAS (the largest single abalone farm in the southern hemisphere) and Port Lincoln SA. Yumbah produces both greenlip and hybrid greenlip-blacklip abalone for the live export market into Hong Kong, the broader Asian restaurant trade, Singapore and the Australian domestic premium retail and restaurant trade.

Australian Bight Abalone at Port Lincoln SA is the second major farmed abalone operator, running an offshore lease system supplemented by land-based grow-out. Tasmanian Abalone Council coordinates the wild fishery with quota allocations across the state's three abalone zones. The farmed abalone HVAC envelope is unusual in Australian seafood — large land-based grow-out halls with seawater throughput at 50 to 200 megalitres per day, micro-algae production tanks for hatchery feed, broodstock conditioning at controlled temperature, larval rearing in PC2 biocontainment hatchery construction, and live-export packing halls with controlled atmosphere shipping container loading at 6 to 10 degrees Celsius for the 48 to 72 hour transit to Asia.

Oysters — Coffin Bay, Sydney Rock and the three commercial species

Australian oyster production runs three commercial species across three geographic clusters. Pacific oysters (Crassostrea gigas) are produced predominantly at Coffin Bay SA (the Coffin Bay Oyster Farmers Association cooperative coordinates roughly forty growers), at the Tasmanian Oyster Company and the Tasmanian East Coast oyster cluster, and in smaller volumes in Port Stephens NSW. Sydney Rock oysters (Saccostrea glomerata) are produced along the NSW coast from the Hawkesbury River south to Eden, with major producers around Wallis Lake, Port Stephens, the Hawkesbury and the Clyde River, and represent the heritage Australian oyster species. Native Angasi oysters (Ostrea angasi) are produced in smaller volumes by specialty operators across South Australia, Victoria and Tasmania.

The oyster processing HVAC envelope centres on the shucking hall (opening tables with continuous saltwater spray and shell waste disposal), the wash hall with ozone disinfection, the chilled holding rooms at 0 to 4 degrees Celsius, the live-shipping packing rooms with the shell-on packed product at controlled temperature, and the depuration tanks for the bivalve cleansing cycle that is mandatory for any oyster destined for fresh consumption under FSANZ 4.2.1 and the various state shellfish quality assurance programmes. Coffin Bay specifically runs the largest single Australian Pacific oyster cluster with integrated wash-and-pack operations that supply the supermarket retail channel, the food service channel and the Hong Kong and Singapore export markets.

Prawns — Australian Prawn Farms, Crystal Bay, Pacific Reef and the wild fleet

Australian prawn production combines a substantial wild capture sector (the Spencer Gulf SA king prawn fishery, the Gulf of Carpentaria QLD banana prawn fishery, the Torres Strait QLD tiger prawn fishery and the various NSW estuarine prawn fisheries) with a fast-growing farmed sector based on vannamei production in tropical Queensland and northern New South Wales. Australian Prawn Farms at Yamba NSW is the largest single farmed prawn operation in New South Wales, producing both vannamei and black tiger prawn. Crystal Bay Prawns at Burdekin QLD operates one of the largest vannamei farms in Australia. Pacific Reef Fisheries at Ayr QLD is a major vannamei producer with integrated processing and snap-freeze capacity. The Spencer Gulf wild prawn fleet at Port Lincoln SA supplies the Sealord Port Lincoln and various other South Australian processors.

The prawn processing HVAC envelope centres on the head-on shell-on receival and grading line, the heading and shelling line (where the offal generation is concentrated), the deveining and peeling line, the snap-freeze tunnel at minus 30 to minus 40 degrees Celsius for IQF product, the cooking line for cooked prawn product, the brine glazing tank for IQF protection, and the packing room with vacuum-sealed and MAP packaging. Prawn processing offal generates one of the most aggressive odour profiles in Australian food manufacturing — trimethylamine TMA, ammonia, H2S and proteinaceous VOCs — and the odour control scope is non-trivial.

Yellowtail Kingfish and emerging species — Clean Seas Seafood

Clean Seas Seafood at Port Lincoln SA is the pioneering Australian Yellowtail Kingfish (Seriola lalandi) producer, operating both marine grow-out pens in the Spencer Gulf and a land-based hatchery for the controlled spawning cycle that distinguishes Clean Seas from earlier wild-caught broodstock attempts. Clean Seas supplies Yellowtail Kingfish into the Japanese, US and EU sashimi-grade export market, with primary processing at the Port Lincoln plant including the WPI (whole, processed, individual) fillet line and the gutting and bleed-out line that determines sashimi-grade quality. Yellowtail Kingfish processing demands the most rigorous gutting-line HVAC envelope of any Australian finfish because of the sashimi-grade product specification — surface bacterial load on the finished fillet has to remain below the Japanese MAFF import specification or the consignment is rejected at port.

Seafood canneries — tuna, mackerel and the regional specialty operations

Australian seafood canning is concentrated in three streams. The tuna canning cluster operates at Eden NSW (the major southern bluefin tuna processing capacity), at the Sealord Port Lincoln facility, and at various smaller specialty operators. The mackerel canning capacity sits primarily at Sealord Port Lincoln. The specialty seafood canning sector includes salmon canning, abalone canning at the Australian Bight Abalone facility, oyster canning at boutique operators and various smaller specialty operations. Canning HVAC differs fundamentally from chilled finfish processing because the retort sterilisation autoclave creates a saturated steam atmosphere at 115 to 125 degrees Celsius in the retort hall, and the building HVAC has to manage the latent heat and condensation load through dedicated stainless ductwork with V-groove drip-tray construction on horizontal runs.

Mussels, scallops and emerging shellfish

Mussel production is concentrated in Spring Bay TAS (the largest Australian mussel cluster), Port Phillip Bay VIC and the South Australian gulf systems, with rope-grown and dropper-grown product for the domestic retail and food service channel. Scallop production combines the wild dredge fishery in Bass Strait and the Hervey Bay QLD scallop fishery with smaller farmed scallop trials. Mussel and scallop processing HVAC follows the broader bivalve processing envelope with the shucking hall, wash hall, chilled holding and live-shipping or IQF packing rooms.

What makes aquaculture and seafood processing HVAC mechanically distinctive

Chloride load from continuous saltwater and brine exposure

Australian fish and seafood processing operates with continuous saltwater wash-down at the gutting line, the heading line, the filleting line and the shellfish opening tables. Add brine NaCl mist from the brine glazing tanks on IQF product, evaporated seawater chloride from open shellfish wet-storage tanks, the coastal aerosol chloride load that affects every Tasmanian, Spencer Gulf SA, NSW coastal and Queensland coastal site, and the chlorinated CIP sanitation chemistry, and the duct chloride load is severe. Standard 304L austenitic stainless steel develops chloride stress-corrosion cracking and chloride pitting within five to seven years in this environment. 316L austenitic stainless steel — with the 2 to 3 percent molybdenum addition — is the AS/NZS 4674 and FSANZ 4.2.1 default for production-zone duct above open product. The molybdenum confers the chloride pitting resistance that 304L lacks, and the operating life of correctly specified 316L duct in seafood processing is twenty to thirty years.

Ammonia refrigeration at industrial scale — the IQF tunnel and blast freezer

Fish and seafood processing is one of the largest industrial users of R-717 ammonia refrigeration in Australia after the red meat sector. Every major Atlantic salmon, ocean trout, prawn snap-freeze, IQF tuna and abalone freezing facility operates ammonia plant at scale, governed by AS/NZS 60079.10.1 hazardous area classification, AS/NZS 1677 Parts 1 to 4 Refrigerating Systems Safety, and AS/NZS 5149 Refrigerating Systems and Heat Pumps Safety and Environmental Requirements. The Safe Work Australia workplace exposure standard for ammonia is 25 ppm 8-hour TWA and 35 ppm 15-minute STEL. The HVAC duct engineering response is dedicated 316L stainless machinery room emergency exhaust at 30 air changes per hour, wet scrubber discharge train, continuous ammonia detection with two-stage alarm at 15 ppm and shutdown at 25 ppm, the absolute prohibition of galvanised duct in any space where wet ammonia is possible, and AS/NZS 60079 Class I Zone 2 hazardous area duct routing through the plant room envelope. Bonded conductive joints maintain electrical continuity to earth across the hazardous area duct package.

Hydrogen sulphide from spent feed water and anaerobic offal

The recirculating aquaculture system biological filter, the spent feed water settling tank, and the anaerobic offal collection in any prawn or fish processing offal stream all generate hydrogen sulphide H2S as a metabolic by-product. The Safe Work Australia workplace exposure standard for H2S is 10 ppm 8-hour TWA and 15 ppm 15-minute STEL — the most restrictive industrial gas exposure standard in Australian workplace standards apart from some chemical-specific limits. The HVAC duct response is dedicated 316L stainless extract over the spent feed water tank, the offal hopper and the biofilter inlet, with continuous H2S monitoring at the worker breathing zone height, two-stage alarm at 5 ppm and shutdown at 10 ppm, and integration with the wet scrubber or biofilter discharge train to oxidise the H2S to elemental sulphur or sulphate before atmosphere release.

Chloramine and ozone from sanitation and wash water chemistry

Seafood processing sanitation combines high-pressure water wash-down with chlorinated alkaline foam, peracetic acid sanitiser, quaternary ammonium compounds and increasingly ozone disinfection of the wash water and the bivalve depuration tank water. The chloramine vapour from chlorine reacting with ammonia in the protein wash stream is a respiratory irritant with a workplace exposure standard of 0.5 ppm 15-minute STEL. Ozone at the wash hall has a workplace exposure standard of 0.1 ppm 8-hour TWA. The HVAC duct response is dedicated extract over the sanitation chemistry feed point, the foam application area and the wash hall, with continuous chloramine and ozone monitoring at the worker breathing zone height. The duct material is 316L stainless throughout because both chloramine and ozone are aggressive on galvanised duct.

Aerosolised proteinaceous mist and Listeria management

The gutting line, the heading line, the filleting line, the shucking bench and the prawn shelling line all generate aerosolised proteinaceous mist that accumulates on duct surfaces and demands daily sanitation. Listeria monocytogenes is the principal bacterial concern in Australian seafood processing — cold-smoked salmon in particular is a recognised Listeria risk product and the AQIS export licence and FSANZ 4.2.1 compliance regime both require active Listeria monitoring with positive-release testing of finished product. The duct surfaces above open product zones are the principal Listeria reservoir in any seafood plant if the construction is wrong. Smooth-bore 316L stainless with continuous welded longitudinal seams, internal radii without sharp corners, removable cleaning panels at 3 metre intervals, V-groove drip-tray construction on horizontal runs and no internal insulation are the construction standard.

Saturation humidity and continuous wash-down conditions

The gutting floor, the heading floor and the filleting floor all operate at near 100 percent relative humidity with continuous water on the floor and continuous saltwater wash-down on the production line. Standard galvanised ductwork at the ceiling above these zones drips condensate continuously, creating a sanitation hazard and a Listeria reservoir. The duct construction has to be vapour-tight at every seam, sloped on horizontal runs to drain condensate to dedicated drains, fabricated with V-groove drip-tray bottom profile to capture condensate before it drips, and free of internal insulation that would accumulate biological load. Repeat Listeria findings in Australian salmon plants over the last decade have traced back to inaccessible duct interiors and standing condensate on inadequately sloped horizontal runs.

The cold chain envelope from harvest to dispatch

The cold chain runs from the harvest receival at chilled brine immersion (0 to 2 degrees Celsius), through the gutting floor at 4 to 8 degrees Celsius, into the chilled holding at 0 to 4 degrees Celsius, through the IQF tunnel at minus 30 to minus 40 degrees Celsius, and onward to the frozen storage at minus 18 to minus 25 degrees Celsius or the cryogenic IQF tunnel at much lower surface contact temperatures with liquid nitrogen or liquid CO2 spray. AS 4326 governs cold chain HACCP for the full sequence. The HVAC duct construction has to manage vapour migration, condensate drainage, defrost cycle accommodation and pressurisation cascade across the full temperature spectrum. Pre-insulated 316L stainless panel duct is the standard for the cold chain envelope on every Australian salmon, prawn and abalone processing plant.

Salmon and trout hatchery RAS — the freshwater recirculating envelope

The recirculating aquaculture system RAS hatchery is the upstream HVAC envelope of every Tasmanian Atlantic salmon and ocean trout operation. Tassal operates a major land-based RAS at Triabunna TAS for smolt production and is investing in further land-based capacity. Huon Aquaculture operates the Forest Home Hatchery as one of the most engineering-intensive Australian salmon hatcheries. Petuna operates the Cressy hatchery as a freshwater RAS supplying smolt to both Atlantic salmon and ocean trout grow-out. The Australian interest in Atlantic Sapphire-style land-based RAS at industrial scale has driven the conversation around ATRAS (Australian Tank-based Recirculating Aquaculture System) capacity investment over the medium term. The HVAC envelope of an Atlantic salmon RAS is one of the most complex in Australian aquaculture.

RAS process and gas management

A recirculating aquaculture system runs the rearing water continuously through biological filtration (nitrifying biofilter beds converting ammonia to nitrite to nitrate), mechanical filtration (drum filter or radial-flow settler), ozone or UV sterilisation, oxygenation (pure O2 injection or low-head oxygenator), CO2 degassing (stripping column or vacuum degasser), pH adjustment and temperature control. The fish biomass releases ammonia (NH3 and ammonium NH4+ in pH-dependent equilibrium), CO2 and trace H2S. The fish house atmosphere above the rearing tanks accumulates these gases unless the building HVAC actively scrubs them.

Atlantic salmon RAS recirculating aquaculture system ductwork

The HVAC duct response in an Atlantic salmon recirculating aquaculture system is dedicated 316L stainless overhead extract at 6 to 12 air changes per hour over the rearing hall, capture hoods over each rearing tank at 0.3 to 0.5 metres per second capture velocity to draw evaporated gas before it enters the worker breathing zone, ammonia and CO2 monitoring at multiple points in the building, and discharge via dedicated biofilter or wet scrubber under state EPA Air Quality consent. The capture hood is sized for the tank surface area and the rearing water turnover; a typical 30 cubic metre rearing tank with 1 to 2 cubic metre per hour turnover generates a capture exhaust requirement of 0.5 to 1.0 cubic metres per second per tank.

SBKJ supplies the RAS hatchery overhead extract trunk using the SBAL-V at 316L for the rectangular section, the SBFB-1500 spiral tubeformer for the round trunk sections, and the SB-ZF1500 continuous TIG stitchwelder for the hygienic longitudinal seam where the duct passes over the rearing tanks. The capture hoods themselves are fabricated on the SBPC1500 plasma cutter for the flange and stiffener preparation with hand-finishing of the inlet face. Mill certificate traceability is preserved through the full fabrication chain because the Tasmanian DPIPWE biosecurity audit verifies material certification across the hatchery envelope.

PC2 biocontainment construction for disease-investigation zones

Broodstock holding and disease-investigation zones in any Australian salmon or aquaculture hatchery operate under AS/NZS 2243.3 Physical Containment Level 2 (PC2) biocontainment construction. The PC2 envelope is a defined hygiene zone with one-way airflow from clean to dirty, HEPA-filtered supply air, separate extract through HEPA filtration before discharge, and ID badging for entry to the zone. The duct construction is smooth-bore 316L stainless with welded longitudinal seams, sealed-seam construction holding the cascade differential, and gas-tight isolation dampers at every penetration. Tasmanian DPIPWE biosecurity policy requires PC2 construction in any aquaculture hatchery zone where AGD (amoebic gill disease), POMS (Pacific oyster mortality syndrome) or other notifiable disease investigation is performed.

Ozone and oxygen system safety

The ozone generator and the pure oxygen injection system in any RAS hatchery introduce additional HVAC duct considerations. Ozone leaks at the generator or the injection point are managed by dedicated extract with ozone monitoring at 0.1 ppm 8-hour TWA alarm. Pure oxygen accumulation in any confined space increases the fire risk on adjacent combustible material and any oxygen-enriched atmosphere zone is treated as a Class III hazardous area under AS/NZS 60079 for fire protection design. The HVAC duct response is dedicated extract at the ozone generator and at the oxygen injection skid, continuous monitoring at the breathing zone height, and absolute prohibition of any oil-lubricated equipment in the oxygen-enriched zone.

Salmon marine grow-out support infrastructure

The marine grow-out pens at Macquarie Harbour, Hideaway Bay, the D'Entrecasteaux Channel, Storm Bay and the Tasman Peninsula are open marine cages and the HVAC engineering brief is limited to the support infrastructure on shore — the feed barge accommodation huts, the dive support and harvest support buildings, the smolt transfer facilities at the wellboat berths, and the cleaner fish (wrasse and lumpfish) holding facilities. Duct material is 316L stainless throughout because every coastal Tasmanian site sits within the salt aerosol envelope, and the operating life of any galvanised duct in this environment is limited to three to five years before chloride attack drives replacement. The smolt transfer hall HVAC manages the post-transit acclimation of smolt arriving from the freshwater hatchery; controlled temperature transition prevents thermal shock and the building extract handles the elevated humidity and ammonia from the transfer water.

Harvest receival and chilled brine immersion

Salmon and ocean trout harvest at Tasmanian operations is performed by wellboat (live-haul vessel) transit to the processing plant followed by stunning and chilled brine immersion to halt biological activity and lock in flesh quality. The harvest receival hall at Tassal Huonville, Petuna Devonport and Huon Parramatta Creek operates a chilled brine reception tank at 0 to 2 degrees Celsius with continuous brine circulation through plate heat exchangers. The HVAC envelope of the harvest receival hall combines elevated humidity (the brine tank generates significant evaporative load), chloride aerosol from the brine, the bleed-out blood load from initial processing, and the cold-temperature operation of the brine chiller plant.

Duct construction is 316L stainless throughout with welded longitudinal seams, capture hoods over the brine tank surface at 0.3 metres per second capture velocity, dedicated extract for the bleed-out line at 0.5 metres per second, and pressurisation at minus 15 Pascals relative to adjacent process zones to contain aerosol within the receival hall envelope. The chiller plant integration follows the AS/NZS 60079 Class I Zone 2 hazardous area classification because the brine chillers use R-717 ammonia under AS/NZS 1677.

Gutting and heading floor — the wet-floor envelope

The gutting and heading floor is the start of the production envelope proper. The HVAC duct engineering brief here is the most demanding in the seafood sector: continuous saltwater wash-down, aerosolised blood and offal mist, ammonia from the gutting line offal stream, biological aerosol containing endotoxin and Listeria monocytogenes, the chloride load from the wash water, and the wet-floor saturation humidity of 95 to 100 percent RH. The gutting floor at Tassal Huonville and Petuna Devonport processes 30,000 to 60,000 salmon per day at peak season; the Clean Seas Yellowtail Kingfish line at Port Lincoln runs lower volume but higher sashimi-grade quality requirement.

Salmon processing HVAC duct — the gutting line standard

The standard salmon processing HVAC duct envelope on the gutting line is 316L austenitic stainless throughout, fabricated on the SBAL-V auto duct line in 1.2 to 1.5 millimetre coil thickness with continuous TIG-welded longitudinal seams using the SB-ZF1500 stitchwelder. Capture hoods over the gutting station, the heading station and the offal conveyor at 0.5 metres per second minimum capture velocity per the ACGIH Industrial Ventilation Manual. Duct slope on horizontal runs at 30 degrees minimum to drain condensate and wash-water load. Removable cleaning panels at 3 metre intervals for routine sanitation access. External insulation only because internal insulation accumulates biological load. The exhaust is at minus 15 to minus 25 Pascals pressurisation relative to adjacent process zones to contain aerosol within the gutting floor envelope.

V-groove drip-tray construction

Every horizontal duct run above an open product zone is fabricated with V-groove drip-tray bottom profile to capture condensate and route it to dedicated drain points rather than allowing drip onto product. The V-groove is formed on the SBAL-V auto duct line during the sheet forming sequence with custom tooling, and the drain points are tapped through the bottom profile at the low points of the duct run. The drip-tray construction is the single most important hygienic detail on a fish processing gutting floor duct envelope — condensate drip onto product is the most common AQIS export licence audit finding and the easiest one to engineer out at the construction stage.

Welded longitudinal seam for full wash-down

The welded longitudinal seam is the hygienic-finish construction default for any duct passing over an open product zone in a fish processing plant. The standard Pittsburgh lock and snap-lock construction is acceptable in dry plant rooms and building services zones but is not acceptable above product because the seam interior accumulates wash-water load, sanitation chemistry residue and biological matter. The SBSF-1525 stitchwelder runs the spot-weld hygienic seam at production speed for the standard hygiene zone application, and the SB-ZF1500 continuous TIG stitchwelder runs the fully sealed welded seam for the AQIS export licence audit envelope and the FSANZ 4.2.1 critical hygiene zones. The continuous TIG seam is internally smooth, externally smooth, vapour-tight and aerosol-tight, and is the highest hygienic finish achievable on machine-formed sheet metal duct.

Filleting and trim floor — the chilled mid-zone

Downstream of the gutting and heading floor sits the filleting and trim floor where the gutted carcasses are filleted, the dark muscle removed for premium product grades, the pin bones extracted, and the fillets graded by weight and grade for the downstream packing operation. The room runs at 4 to 6 degrees Celsius with high humidity (80 to 90 percent RH typical) from product evaporation and continuous water wash-down. The aerosol load is lower than the gutting floor but the hygiene standard is higher because the product is exposed and the downstream packing operation depends on the bacterial load at this stage.

The HVAC duct construction is 316L stainless throughout with welded longitudinal seams, HEPA-filtered supply at MERV 14 minimum (and H13 HEPA in export-grade plants targeting the Japanese sashimi market via Clean Seas and Petuna ocean trout), positive pressurisation at plus 10 Pascals relative to the gutting floor and plus 5 Pascals relative to the packing room, and supply air velocity at the product zone below 0.5 metres per second to prevent direct draught on exposed fillet surface. The filleting floor at Clean Seas Yellowtail Kingfish Port Lincoln runs the most rigorous filleting HVAC envelope in Australian seafood because of the sashimi-grade product specification — surface bacterial load on the finished fillet has to remain below the Japanese MAFF import specification.

Smoking kiln — cold-smoke and hot-smoke envelopes

Australian smoked salmon production runs both hot-smoking (60 to 90 degrees Celsius for 2 to 4 hours producing fully cooked product) and cold-smoking (18 to 25 degrees Celsius for 6 to 12 hours producing raw cured product). The Tassal Don Smallgoods Castlemaine VIC facility, the various Tasmanian boutique smokehouses servicing the restaurant trade, and the major retail-channel smokers all operate kilns at scale. The smoke is generated either by hardwood combustion (beech, alder, cherry, manuka or eucalyptus depending on the product line) or by liquid smoke injection. The cold-smoked salmon product is a recognised Listeria risk product under AQIS export licence and FSANZ 4.2.1 compliance, with active Listeria monitoring required at multiple points in the production cycle.

Capture and stack design

The smoke generator capture hood operates at 0.5 metres per second minimum capture velocity per the ACGIH Industrial Ventilation Manual. The capture face area is sized to fully enclose the smoke generator's smoke discharge. The smoke-laden exhaust chimney is 309 stainless on the inner liner for the hot-smoke kiln (the higher chromium and nickel content withstands the 90 degree creosote condensate exposure) with 304 stainless on the outer skin and uninsulated on the inner liner to allow tar and creosote condensate to drain back to the generator. For cold-smoke kilns where the chimney temperature is much lower the construction is 304 stainless throughout. The chimney is sloped at 30 degrees minimum on horizontal runs and equipped with removable cleaning panels at 3 metre intervals for the weekly tar removal cycle.

Fire suppression mandatory

Wet chemical or water mist fire suppression is mandatory in the smoking kiln chimney under AS 1851 and the National Construction Code Volume One. Suppression nozzles are positioned at the chimney entry, at every 6 metre interval along the chimney run, and at the discharge fan inlet. Annual servicing of suppression heads is a non-negotiable operating requirement. The internal-insulation construction error — saturating insulation with tar condensate — is the single most common cause of catastrophic smoking kiln chimney fires in Australian seafood plants and we have rebuilt two Australian salmon smoking chimney systems in the last three years where the original duct contractor specified internally insulated stack.

Discharge stack

The smoke exhaust discharges through a roof-mounted high-velocity stack at minimum 1.5 metres above the highest adjacent roof line and 6 metres horizontally clear of any outdoor air intake on the same or adjacent buildings, per AS 1668.2. Some Australian metropolitan smokehouse operations are required to include particulate filtration or wet scrubbing on the discharge to meet local air quality regulations under state EPA Air Quality consents. Smoke kiln chimney 304 stainless is the standard outer construction, with 309 stainless on the inner liner for hot-smoke applications. SBKJ supplies the chimney fabric using the SBPC1500 plasma cutter for the stack flange preparation and the SB-ZF1500 stitchwelder for continuous TIG seam construction on the inner liner.

IQF tunnel freezer and blast freezer — the snap-freeze envelope

Individual quick freeze (IQF) tunnel freezers and blast freezers are the dominant freezing technology in Australian seafood processing for the higher-value product lines — salmon fillets, prawn snap-freeze, abalone IQF, scallop IQF and the various boutique frozen product lines. The Tassal Huonville processing plant operates an ammonia IQF tunnel freezer at scale for the salmon fillet packaging line. The Australian Prawn Farms Yamba snap-freeze tunnel handles head-on shell-on premium product and peeled IQF product on parallel lines. The various blast freezer rooms at every major Australian seafood processor handle the bulk frozen product going to the supermarket retail channel and the food service channel.

Ammonia refrigeration cold room ductwork — the standard envelope

The IQF tunnel and blast freezer at major Australian seafood processors run R-717 ammonia direct expansion or pumped circulation under AS/NZS 1677 and AS/NZS 60079.10.1 Class I Zone 2 hazardous area classification. The evaporator coils are housed in dedicated coil plenums in the tunnel or freezer envelope, with high-velocity air discharge through the coil and supply air diffusion into the freezer via overhead spiral or rectangular duct. SBKJ supplies the evaporator coil plenum housings using the SB-ZF1500 stitchwelder for continuous TIG seam construction in 316L stainless — the welded seam is critical because the plenum sits directly over the product and any condensate drip during defrost cycle is a sanitation finding.

Air velocity and pull-down rate

Air velocity across the product in the IQF tunnel is 3 to 6 metres per second to drive the high heat transfer required for individual quick freeze. The pull-down rate target is below 30 minutes from product entry at 4 degrees Celsius to product exit at minus 18 degrees Celsius internal temperature for the salmon fillet line, and below 20 minutes for the prawn snap-freeze line. The blast freezer operates at minus 30 to minus 40 degrees Celsius with air velocity 3 to 6 metres per second across the product to drive the high heat transfer rate.

Pre-insulated panel duct

The supply ductwork inside the IQF tunnel and the blast freezer is pre-insulated 316L stainless panel duct with continuous vapour barrier on the warm side. Insulation thickness is typically 75 to 100 millimetres of closed-cell PIR foam to keep the outer surface above ambient dewpoint with safety margin and to handle the thermal gradient across the panel between the minus 40 degree freezer envelope and the building services ambient. Penetrations through the freezer envelope are vapour-tight with butyl gasket seals on both warm and cold sides and factory-foamed sleeves. Hangers are thermal-break to prevent heat bridging across the duct support to the warm structure above. The high air velocity demands reinforced duct hangers and stiffened panel construction to handle the dynamic load.

Defrost cycle and door air curtain

The IQF tunnel and blast freezer require periodic hot-gas or electric defrost on the evaporator coils to remove the ice build-up that accumulates during operation. The defrost cycle generates a substantial liquid water load that has to be managed by the panel duct condensate drainage scheme. Door air curtains at every freezer access door operate at 1.5 to 2.5 metres per second velocity to limit warm air ingress during product loading and unloading. The door air curtain integrates with the freezer access door interlock and the production line control system.

Cryogenic IQF tunnel — the premium product alternative

Some premium product lines — high-end Yellowtail Kingfish sashimi-grade fillet for the Japanese export market, premium Tasmanian salmon for the Hong Kong restaurant trade, and the Australian Prawn Farms Yamba head-on shell-on premium product — use cryogenic IQF tunnels with liquid nitrogen (LN2) or liquid CO2 spray for the fastest possible freeze and the highest quality preservation. The cryogenic envelope introduces an AS/NZS 60079 hazardous area dimension because liquid nitrogen evaporation displaces oxygen and creates an asphyxiation hazard. Oxygen exposure standard is 19.5 to 23.5 percent volume and concentrations outside this window trigger emergency alarm and evacuation. The HVAC duct response is dedicated ventilation around the cryogenic tunnel at 30 air changes per hour minimum, continuous oxygen monitoring, spark-resistant motor and damper actuator construction, and emergency exhaust mode interlock with the cryogenic supply shut-off.

Canning retort hall — the saturated steam envelope

Australian seafood canning operates retort sterilisation autoclaves at 115 to 125 degrees Celsius and 70 to 200 kPa overpressure for 45 to 90 minutes per cycle. The retort hall atmosphere is saturated with steam and the building HVAC has to manage the latent load, the condensation drip risk, and the chloride load from any spilled brine. The Sealord Port Lincoln SA mackerel and tuna cannery, the Eden NSW tuna cannery cluster, the Australian Bight Abalone Port Lincoln cannery and various boutique tuna and salmon canneries across regional Australia all operate retort halls at scale.

Retort hall ventilation

The retort hall ventilation has to manage the steam plume released during retort opening at the end of each sterilisation cycle. The retort opening event releases a substantial steam volume into the hall atmosphere over a 30 to 60 second window. The HVAC duct response is dedicated capture hoods over each retort discharge point at 1.0 metres per second capture velocity, integrated with the retort control system to ramp up the capture exhaust during the discharge window, and continuous building extract at 12 to 20 air changes per hour to manage the baseline humidity load.

Duct construction

Duct construction in the retort hall is 316L stainless throughout with welded longitudinal seams. External insulation prevents condensation on the cool exterior in the air-conditioned operator gallery zones. V-groove drip-tray construction on horizontal runs manages the condensate load. The retort cooker exhaust fan housing is 316L stainless fabricated using the SB-ZF1500 stitchwelder. SBKJ supplies the retort hall ductwork using the SBAL-V at 316L and the SBSF-1525 stitchwelder for the longitudinal seam, with the SBFB-1500 spiral tubeformer for the larger trunk diameters.

Hot water and steam plant

The retort hot water and steam supply plant operates at 130 to 150 degrees Celsius hot water and 70 to 200 kPa saturated steam. The boiler room HVAC scope includes combustion air supply, flue gas extract and emergency ventilation. Heat recovery from the retort discharge water (the cooling cycle at the end of each sterilisation run releases substantial heat at 80 to 100 degrees Celsius) is increasingly standard practice on new Australian seafood cannery installations and reduces the primary fuel demand by 20 to 30 percent depending on plant configuration. The HVAC duct scope includes the heat recovery loop ductwork.

Abalone propagation — the algae and seawater envelope

Australian abalone propagation at Yumbah Aquaculture Narrawong VIC and Smithton TAS and at Australian Bight Abalone Port Lincoln SA includes broodstock conditioning, larval rearing, micro-algae production and grow-out tanks. The HVAC envelope is unusual in Australian seafood because of the algae and seawater chemistry combinations that are not encountered elsewhere.

Yumbah abalone Narrawong — algae propagation tank vapour management

The Yumbah Narrawong micro-algae production tanks generate dimethyl sulphide DMS, dimethyl disulphide and other volatile sulphur compounds as algae metabolism by-products. DMS has a workplace exposure standard of 0.5 ppm 8-hour TWA under Safe Work Australia and is detectable by smell at much lower concentrations — the algae production hall has a characteristic marine odour that is largely DMS-driven. The HVAC duct response is dedicated 316L stainless overhead extract over the algae production tanks at 6 to 8 air changes per hour, capture hoods at the tank perimeter at 0.3 metres per second capture velocity, and discharge via a biofilter polish stage before atmosphere release.

Larval rearing PC2 hatchery

The larval rearing zone in any Australian abalone hatchery operates as a defined PC2 biocontainment zone under AS/NZS 2243.3. The PC2 envelope provides biosecurity isolation from any incoming pathogen risk — abalone viral ganglioneuritis AVG, perkinsus and other notifiable shellfish disease — and from any outgoing biosecurity risk to surrounding water bodies. Duct construction is smooth-bore 316L stainless with welded longitudinal seams, sealed-seam construction holding the cascade differential at plus 15 Pascals relative to the surrounding building, gas-tight isolation dampers at every penetration, and HEPA-filtered supply and HEPA-filtered extract.

Grow-out hall ventilation

The abalone grow-out tanks at Yumbah and Australian Bight Abalone operate large land-based pump-ashore systems with seawater throughput at 50 to 200 megalitres per day depending on the facility scale. The grow-out hall atmosphere accumulates evaporated seawater chloride, trace ammonia from the abalone biomass and the residual algae odour from the abalone feed (predominantly cultured algae for the early life stages, transitioning to harvested kelp for grow-out). HVAC duct construction is 316L stainless throughout for the building extract trunk, with 6 to 12 air changes per hour minimum building ventilation rate and capture hoods over the high-evaporation zones (incoming seawater feed manifold, outgoing seawater discharge sump).

Live-export packing hall

Yumbah's principal export product is live abalone shipped to Hong Kong, Singapore and other Asian premium restaurant markets in controlled-atmosphere shipping containers. The live-export packing hall operates at 6 to 10 degrees Celsius with HEPA-filtered supply, plus 10 Pascal pressurisation relative to adjacent zones, and 316L stainless ductwork throughout. The packing cycle prepares the live abalone in moist absorbent packing material under controlled temperature and humidity for the 48 to 72 hour transit from Yumbah to the Asian wholesale market.

Oyster hatchery hygienic duct — the bivalve envelope

Australian oyster production combines hatchery-reared spat (from Tasmanian Oyster Company, NSW Department of Primary Industries oyster hatcheries, and various commercial hatchery operators) with grower-stage on-lease grow-out and downstream processing at the shucking hall and live-shipping packing room. The HVAC envelope across the oyster value chain has the most demanding hygiene and biosecurity requirement of any Australian seafood sector because of the Pacific oyster mortality syndrome POMS risk and the various Vibrio risks associated with shellfish consumption.

Pacific oyster hatchery PC2 envelope

Oyster hatcheries operate as PC2 biocontainment zones under AS/NZS 2243.3 with one-way airflow from clean to dirty, HEPA-filtered supply, separate HEPA-filtered extract, and biosecurity isolation procedures at every access point. The hatchery rearing tanks operate at controlled temperature 18 to 22 degrees Celsius depending on the species and life stage, with micro-algae feed production in adjacent zones. Duct construction is 316L stainless throughout with welded longitudinal seams.

Coffin Bay oyster shucking and ozone wash hall

The Coffin Bay Oyster Farmers Association cooperative coordinates the largest Pacific oyster cluster in Australia, with roughly forty growers producing on-lease oysters in the Coffin Bay marine waters. The downstream processing at the cooperative wash-and-pack facility includes the shucking hall (opening tables with continuous saltwater spray and shell waste disposal), the wash hall with ozone disinfection of the shucked oyster meat, the chilled holding rooms at 0 to 4 degrees Celsius, and the live-shipping packing rooms with the shell-on packed product at controlled temperature for the supermarket retail and Asian export markets.

The HVAC duct response in the Coffin Bay shucking hall is dedicated 316L stainless overhead extract at 12 to 20 air changes per hour, capture hoods over the shucking tables at 0.3 metres per second capture velocity to draw the saltwater spray and the shell debris aerosol, and discharge to atmosphere via a HEPA polish stage. The ozone wash hall HVAC manages the residual ozone load with continuous monitoring at the worker breathing zone height and two-stage alarm at 0.05 ppm and 0.1 ppm. The cold holding rooms use pre-insulated 316L stainless panel duct.

Sydney Rock oyster operations

The Sydney Rock oyster fleet along the NSW coast from Wallis Lake through Port Stephens, the Hawkesbury River, the Clyde River and south to Eden NSW operates a similar processing envelope to the Coffin Bay Pacific oyster cooperative, with the additional dimension of the depuration cycle that NSW oysters undergo before retail release. The depuration tanks at the major NSW oyster processors operate at controlled UV sterilisation of the circulating seawater to ensure the bivalve cleansing cycle removes any incoming bacterial load. The depuration hall HVAC manages the UV ozone by-product and the chloride aerosol from the depuration tanks.

Tasmanian East Coast oyster cluster

The Tasmanian Oyster Company and the various Tasmanian East Coast oyster growers operate the third major Australian oyster cluster. The Tasmanian POMS exposure has reshaped the industry over the last decade and the hatchery and grow-out operations now include extensive biosecurity protocols under Tasmanian DPIPWE policy. The HVAC envelope follows the broader oyster processing template with 316L stainless throughout and PC2 biocontainment construction in the hatchery zone.

Prawn processing food grade stainless — the offal-heavy envelope

Prawn processing at Australian Prawn Farms Yamba NSW, Crystal Bay Prawns Burdekin QLD, Pacific Reef Fisheries Ayr QLD and the Spencer Gulf wild prawn fleet handlers in Port Lincoln SA operates one of the most offal-heavy production envelopes in Australian seafood processing. The heading line, the shelling line and the deveining line generate substantial offal load (head, shell and intestinal tract) that is either ground for fishmeal production, composted for agricultural application, or anaerobically digested for biogas production at the larger operators.

Head-on shell-on snap freeze envelope

The Australian Prawn Farms Yamba premium product line is head-on shell-on snap-freeze prawn for the Japanese, Hong Kong and Singapore high-end restaurant market. The snap-freeze envelope demands the fastest possible freeze to preserve the cellular integrity and the visual presentation quality of the premium product — cryogenic liquid nitrogen IQF tunnel or high-velocity ammonia blast freezer at minus 40 degrees Celsius are the standard options. The HVAC duct envelope on the snap-freeze line follows the broader IQF tunnel construction with 316L stainless throughout and the additional ventilation around any cryogenic equipment under AS/NZS 60079.

Cooked prawn line

The cooked prawn product line at Crystal Bay Prawns and Pacific Reef Fisheries handles whole cooked prawns and cooked peeled prawn product for the supermarket retail channel. The cooker operates at 90 to 95 degrees Celsius for 2 to 5 minutes depending on the prawn size. The cooking hall HVAC manages the steam load (similar profile to the retort hall but at lower temperature and humidity) with dedicated capture hoods over the cooker discharge point and building extract at 12 to 20 air changes per hour.

Brine glazing tank

IQF prawn product is brine-glazed after the snap-freeze cycle to provide a protective ice glaze that prevents freezer burn during the downstream storage and distribution chain. The brine glazing tank operates at minus 5 to minus 10 degrees Celsius with continuous NaCl brine circulation. The glazing hall HVAC manages the brine aerosol load with dedicated 316L stainless capture hoods and discharge to the building exhaust trunk.

Offal grinder and bone crusher odour control

The prawn offal grinder and the bone crusher at the larger operators generate the most aggressive odour load in any Australian seafood plant. The offal stream releases trimethylamine TMA, ammonia, hydrogen sulphide and proteinaceous volatile organic compounds. State EPA Air Quality regulations limit the odour boundary concentration at 2 to 5 odour units depending on jurisdiction. The standard odour control train is dedicated 316L stainless duct from each grinder hood and offal hopper at 0.5 metres per second capture velocity to a wet scrubber (sodium hypochlorite or sodium hydroxide scrubbing chemistry), followed by a biofilter polish with engineered media bed (commonly wood bark, peat or proprietary synthetic media). Discharge stack at 1.5 metres per second minimum exit velocity and 1.5 metres minimum above adjacent occupied buildings.

SBKJ supplies the offal extract ductwork using the SBAL-V at 316L and the SBFB-1500 spiral tubeformer for the larger trunk diameter sections. The biofilter media bed sits in a separate enclosure with concrete plenum below and engineered media bed above; the HVAC duct delivers the conditioned exhaust into the plenum and through the media bed. Annual media replacement on the biofilter and quarterly chemistry refresh on the wet scrubber are the standard operating cycle.

Yellowtail Kingfish gutting and WPI fillet line — the sashimi-grade envelope

The Clean Seas Seafood Yellowtail Kingfish operation at Port Lincoln SA runs the most rigorous gutting-line HVAC envelope of any Australian finfish processor because of the sashimi-grade product specification for the Japanese, US and EU export markets. The gutting and bleed-out line determines the sashimi-grade quality of the finished product, and the surface bacterial load on the finished fillet has to remain below the Japanese MAFF import specification or the consignment is rejected at port.

The HVAC duct envelope on the Clean Seas Yellowtail Kingfish gutting line is 316L stainless throughout with continuous TIG-welded longitudinal seams on every duct piece passing over the production line. HEPA-filtered supply at H13 specification (rather than the MERV 14 standard for general seafood). Plus 15 Pascal pressurisation relative to adjacent zones. Capture velocity 0.8 metres per second at the gutting station (higher than the standard 0.5 metres per second to manage the aerosol load from the larger kingfish carcasses). V-groove drip-tray construction on every horizontal duct run. Removable cleaning panels at 2 metre intervals (closer than the standard 3 metre intervals) for the more frequent sanitation cycle that the sashimi-grade product requires.

WPI fillet line construction

The WPI (whole, processed, individual) fillet line at Clean Seas Port Lincoln runs the filleting, pin bone extraction, dark muscle removal and grading operations on individual sashimi-grade fillets. The line operates at 4 to 6 degrees Celsius with H13 HEPA-filtered supply and plus 20 Pascal pressurisation. The duct construction is 316L stainless with continuous TIG-welded longitudinal seams using the SB-ZF1500 stitchwelder and the SBAL-V auto duct line in 316L. Supply diffusers are positioned to deliver the design air change rate (40 to 60 air changes per hour) without exceeding 0.4 metres per second velocity at the working height.

Tuna processing — the bluefin and yellowfin operations

Australian tuna processing combines southern bluefin tuna (ranched at Port Lincoln SA after wild capture in the Great Australian Bight), yellowfin tuna (longline-caught from the East Coast tuna fishery), and the various other tuna species processed at the Eden NSW cluster and the Sealord Port Lincoln operations. The HVAC envelope on the tuna processing floor follows the broader finfish gutting and filleting template with the additional dimension of the larger carcass mass (200 to 400 kilograms on bluefin tuna versus 4 to 8 kilograms on salmon and trout) which drives the air velocity calibration at the processing stations.

Bluefin tuna ranching support

The southern bluefin tuna ranching operations at Port Lincoln SA capture wild tuna in the Great Australian Bight and tow the live fish back to fattening pens off Boston Island. The processing for the Japanese sashimi-grade market is performed at the Port Lincoln SA processing facilities with rigorous chilled brine immersion and rapid filleting for the export-quality grade. The HVAC envelope follows the broader sashimi-grade specification with 316L stainless throughout and H13 HEPA-filtered supply on the filleting zone.

Mussel and scallop processing

Mussel processing at the Spring Bay TAS and Port Phillip Bay VIC clusters runs the shucking hall, the wash hall and the cooked-mussel line for the bagged retail product. The HVAC envelope follows the broader bivalve processing template with 316L stainless throughout, 12 to 20 air changes per hour building ventilation, and dedicated capture exhaust over the cooker discharge point on the cooked-mussel line. Scallop processing combines the wild dredge fishery product (delivered as shell-on or shucked depending on the operator) with the smaller-volume farmed scallop product. The HVAC envelope is similar to the mussel and oyster operations.

Fish meal and offal rendering

The larger Australian seafood processors increasingly operate on-site or shared fish meal production capacity for the rendering of processing offal and downgrade product into fish meal for the aquaculture feed industry. The fish meal cooker runs at 90 to 105 degrees Celsius with substantial steam and odour load. The HVAC duct response is dedicated 316L stainless or FRP duct from each cooker hood and centrifuge hood to a wet scrubber, followed by biofilter polish. The fish meal operation odour profile is one of the most aggressive in Australian food manufacturing and the wet scrubber chemistry typically combines sodium hypochlorite for the volatile fatty acids with sodium hydroxide for the amines.

Ammonia compressor room — AS/NZS 60079 Class I Zone 2

Every major Australian seafood processor runs ammonia refrigeration plant at scale. The ammonia compressor room is the highest-risk machinery room in the facility and is governed by AS/NZS 1677 Parts 1 to 4, AS/NZS 5149, and AS/NZS 60079.10.1 Class I Zone 2 hazardous area classification.

Emergency ventilation rate

AS/NZS 1677 requires emergency ventilation of the ammonia compressor room at 30 air changes per hour minimum, interlocked with the ammonia detection system. Low-level alarm at 15 ppm triggers ramp-up of the ventilation rate; high-level alarm at 25 ppm 8-hour TWA triggers compressor shutdown and full emergency exhaust mode. The compressor room is purpose-built with concrete walls and floor, blast-rated roof construction in the high-volume installations, and dedicated emergency egress at two sides minimum.

Dedicated scrubber exhaust

The compressor room exhaust is routed through a wet scrubber before atmosphere release on most new builds. The scrubber housing is 316L stainless fabricated using the SB-ZF1500 stitchwelder for continuous TIG seam construction. The scrubber inlet duct is 316L stainless or polypropylene-lined depending on the scrubber chemistry. The discharge stack is 1.5 metres minimum above adjacent occupied buildings.

Spark-resistant equipment

Equipment inside the ammonia compressor room is spark-resistant under the AS/NZS 60079 Class I Zone 2 hazardous area classification — ammonia at sufficient concentration is flammable (LFL 15 to 28 percent volume in air). Motor construction, damper actuator construction, lighting and instrumentation all carry IECEx Ex e or Ex d marking. SBKJ supplies the compressor room exhaust ductwork with bonded conductive joints and stainless support hardware to maintain electrical continuity to earth across the Zone 2 envelope.

Eyewash and emergency shower

Every entry to the ammonia compressor room is equipped with eyewash and emergency shower stations under AS 4775 (Emergency Eyewash and Shower Equipment). The brine NaCl mist eyewash provision sits alongside the ammonia emergency provision because both chemistries require immediate eye irrigation in the event of operator exposure. The emergency station is interlocked with the alarm system to log any activation. Worker training under AS/NZS 1677 includes ammonia exposure response and evacuation procedure.

Effluent treatment — DAF and anaerobic digestion

Seafood processing generates substantial effluent — blood, fat trim, offal residue, washdown water with chlorinated cleaning chemistry and the saltwater wash stream. The effluent treatment plant typically combines dissolved air flotation (DAF) for solids and fat removal with anaerobic digestion for organic load reduction and methane biogas generation at the larger operators. The HVAC duct scope on the effluent treatment plant covers the DAF skim collection hood, the anaerobic digester headspace ventilation (Class I Zone 1 or Zone 2 hazardous area under AS/NZS 60079 because methane is the principal gas), the biogas storage gasholder ventilation, the biofilter inlet capture and the building services ventilation around the treatment plant complex. Duct construction is 316L stainless throughout because of the H2S exposure (hydrogen sulphide is the second-largest gas component in raw biogas at 1000 to 3000 ppm volume).

Loading dock — the chilled airlock

The refrigerated transport loading dock is the last HVAC zone in the plant flow. Temperature target is 4 to 8 degrees Celsius to maintain cold chain integrity during the dock loading window per AS 4326. The dock is equipped with high-velocity air curtains at every dock door at 1.5 to 2.5 metres per second velocity to limit ambient air infiltration during truck loading, dock seal integration with the truck trailer body, and dedicated supply air at the dock-side at 316L stainless duct. The Spirit of Tasmania ferry seafood logistics from Devonport TAS to Geelong VIC and Melbourne VIC manages the cold chain through purpose-built refrigerated containers and trucks; the cold chain integrity from the Tassal Huonville or Petuna Devonport plant through the ferry transit to the mainland distribution centres is the critical loading dock engineering consideration. Loading dock HVAC failure is the most common cold chain non-conformance under AS 4326 audit and AQIS dispatch verification.

The Spirit of Tasmania seafood logistics envelope

Tasmanian salmon, ocean trout, abalone, mussel and oyster production travels to the mainland Australian distribution centres predominantly by the Spirit of Tasmania ferry from Devonport TAS to Geelong VIC. The cold chain integrity through the ferry transit is managed by refrigerated containers and refrigerated trucks under AS 4326 with continuous temperature data logging from the Tasmanian plant of origin to the Melbourne mainland distribution centre. The HVAC duct engineering on the Spirit of Tasmania container terminal at Devonport and the Geelong receiving terminal supports the refrigerated container plug-in points and the dock-side handling envelope. The cold chain failure modes through the ferry transit are predominantly thermal rather than ventilation-related, but the dock-side HVAC envelope is the audited interface.

Salmon processing HVAC duct — specific operator scenarios

Tassal Huonville processing plant — the ammonia IQF tunnel freezer

The Tassal Huonville processing plant is the largest single salmon processing line in Australia by throughput. The facility runs the full integrated processing flow from harvest receival through gutting, heading, filleting, trim, packing and IQF tunnel freeze. The ammonia IQF tunnel freezer is the central refrigeration asset on the site and operates under AS/NZS 60079 Class I Zone 2 hazardous area classification with the full ammonia compressor room safety envelope. The HVAC duct package at Tassal Huonville includes 316L stainless throughout the production zone with continuous TIG-welded longitudinal seams, V-groove drip-tray construction on every horizontal run, dedicated capture exhaust at every gutting and heading station, HEPA-filtered supply on the filleting and trim zone, pre-insulated 316L stainless panel duct in the IQF tunnel and blast freezer envelope, and the dedicated ammonia compressor room scrubber exhaust train. SBKJ supplies the production-zone HVAC duct package using the SBAL-V at 316L variant, the SBFB-1500 spiral tubeformer for the round trunk sections, the SB-ZF1500 continuous TIG stitchwelder for the hygienic longitudinal seam, and the SBPC1500 plasma cutter for the larger plate preparation work.

Petuna Devonport ocean trout processing

The Petuna Devonport processing facility runs both Atlantic salmon and ocean trout production lines in parallel. The ocean trout product is the higher-value premium line targeting the Asian sashimi market and the Australian high-end retail and restaurant trade. The Petuna Devonport HVAC envelope follows the broader Tassal Huonville template with the additional consideration that the ocean trout line runs to a more rigorous bacterial load specification because of the sashimi-grade target. The Cressy hatchery RAS upstream of the Devonport processing site supplies smolt to both production lines, with the freshwater hatchery HVAC envelope managed under the broader Petuna engineering scope.

Yumbah abalone Narrawong — algae propagation tank vapour management

The Yumbah Narrawong abalone hatchery and grow-out facility runs the most extensive land-based abalone propagation operation in Victoria. The HVAC envelope includes the broodstock conditioning zone, the larval rearing PC2 hatchery, the micro-algae production tank hall (with DMS and dimethyl disulphide vapour management), the grow-out tank hall, and the live-export packing zone. SBKJ has supplied the 316L stainless duct package for the Narrawong site using the SBAL-V at 316L variant for the rectangular sections, the SBFB-1500 spiral tubeformer for the round trunk sections passing through the algae production hall, and the SB-ZF1500 continuous TIG stitchwelder for the hygienic longitudinal seam on every duct piece passing over the open tanks.

Australian Prawn Farms Yamba — head-on shell-on snap freeze

The Australian Prawn Farms Yamba NSW operation runs the largest farmed prawn snap-freeze line in New South Wales. The head-on shell-on premium product line uses a high-velocity ammonia blast freezer at minus 40 degrees Celsius for the snap-freeze cycle and a cryogenic liquid nitrogen IQF tunnel for the highest-grade premium export product. The HVAC duct package at Yamba includes pre-insulated 316L stainless panel duct in the blast freezer envelope, the AS/NZS 60079 hazardous area duct routing for the ammonia compressor room and the cryogenic LN2 tunnel, the offal grinder odour control train with wet scrubber and biofilter, and the standard production-zone HVAC envelope for the heading, shelling and deveining lines.

Clean Seas Yellowtail Kingfish — gutting and WPI fillet line

The Clean Seas Yellowtail Kingfish operation at Port Lincoln SA runs the most rigorous gutting-line HVAC envelope of any Australian finfish processor. The 316L stainless throughout with continuous TIG-welded longitudinal seams, H13 HEPA-filtered supply, V-groove drip-tray construction, removable cleaning panels at 2 metre intervals, and the higher 0.8 metres per second capture velocity at the gutting station all reflect the sashimi-grade export quality target. SBKJ supplies the Clean Seas Port Lincoln HVAC duct package using the SBAL-V at 316L variant and the SB-ZF1500 continuous TIG stitchwelder for every production-zone duct piece.

Coffin Bay oysters — opening and ozone wash hall

The Coffin Bay Oyster Farmers Association wash-and-pack facility runs the largest single Australian Pacific oyster processing capacity. The shucking hall, the ozone wash hall, the chilled holding rooms and the live-shipping packing rooms all operate under 316L stainless HVAC duct throughout. The ozone wash hall HVAC manages the residual ozone load with continuous monitoring at the worker breathing zone height and the discharge to atmosphere via a HEPA polish stage. SBKJ supplies the Coffin Bay shucking and ozone wash hall HVAC duct package using the SBAL-V at 316L variant and the SBFB-1500 spiral tubeformer for the round trunk sections.

SBKJ machines for the seafood processing HVAC duct package

SBAL-V auto duct line — 316L stainless variant

The SBAL-V auto duct line is the workhorse of the Australian seafood processing HVAC duct fabrication scope. The 316L stainless variant runs coil thickness from 0.6 to 1.5 millimetres with the 1.2 to 1.5 millimetre band as the standard for production-zone duct above open product. The machine integrates the decoiler, the leveller, the punch press for corner notching, the shear for cut-to-length, and the brake press for the sheet folding into rectangular duct cross-section. SBKJ supplies the SBAL-V at 316L to every major Australian seafood processor with a HACCP-compliant production-zone duct package and to the supermarket retail back-of-house refits servicing the seafood counter and the chilled seafood display chain.

SBAL-III auto duct line

The SBAL-III auto duct line is the predecessor model to the SBAL-V and remains in service at several Australian seafood operators. The SBAL-III handles coil thickness from 0.6 to 1.2 millimetres in 304L and 316L variants. SBKJ continues to supply spare parts and engineering support for the SBAL-III installed base.

SBSF-1525 stitchwelder

The SBSF-1525 stitchwelder runs the spot-weld hygienic longitudinal seam at production speed for the standard hygiene zone application. The 1525 millimetre length capacity handles the standard rectangular duct cross-sections used in seafood processing. The stitchwelder is positioned downstream of the brake press on the SBAL-V line and runs in-line with the duct fabrication sequence.

SB-ZF1500 continuous TIG stitchwelder

The SB-ZF1500 continuous TIG stitchwelder runs the fully sealed welded longitudinal seam for the AQIS export licence audit envelope and the FSANZ 4.2.1 critical hygiene zones. The continuous TIG seam is internally smooth, externally smooth, vapour-tight and aerosol-tight, and is the highest hygienic finish achievable on machine-formed sheet metal duct. SBKJ supplies the SB-ZF1500 to every major Australian seafood processor with an AQIS export-licensed production-zone duct package.

SBFB-1500 spiral tubeformer

The SBFB-1500 spiral tubeformer runs the round hygienic spiral duct for the 200 to 1500 millimetre diameter range. The spiral seam is hygienic-finish welded continuously where the duct passes over open product zones. The SBFB-1500 is the standard machine for the trunk extract ductwork on a salmon, prawn or abalone processing plant where the large-diameter round section delivers the required exhaust airflow with the minimum pressure drop.

SBPC1500 plasma cutter

The SBPC1500 plasma cutter handles the larger plate preparation work for fittings, stack flanges, scrubber housings and biofilter plenum sections. The high-definition plasma head delivers a clean cut edge on 1.2 to 1.5 millimetre 316L stainless. SBKJ supplies the SBPC1500 to seafood processing fabricators handling the rendering plant, fish meal cooker and odour control train ductwork.

SBLR-600 longitudinal seam welder

The SBLR-600 longitudinal seam welder runs the continuous TIG seam on bend, tee, reducer and offset fittings. The 600 millimetre seam length capacity handles the standard fitting sizes used in seafood processing. The internal seam grind to a smooth radius after welding is the hygienic finish that the AQIS auditor verifies.

SBTF-1500, SBTF-1602 and SBTF-2020 spiral tubeformer range

The SBTF spiral tubeformer range covers the round duct fabrication scope from the smaller diameter SBTF-1500 (to 1500 millimetres) through the SBTF-1602 (the 1602 millimetre standard for the building services round trunk) and up to the SBTF-2020 (the larger 2020 millimetre diameter for the abalone hatchery hall trunk extract and the larger seafood processing plant extract trunks). The full range runs 316L stainless in addition to the standard 304L and galvanised material options.

Smoking kiln chimney 304/309 stainless — the fabrication standard

The smoking kiln chimney on every Australian salmon hot-smoke and cold-smoke operation is fabricated to a specific construction standard that combines material grade selection with continuous welded seam and the cleaning access provision. The hot-smoke chimney inner liner is 309 stainless to withstand the 90 degree creosote condensate exposure; the outer skin is 304 stainless. The cold-smoke chimney is 304 stainless throughout. SBKJ supplies the smoking kiln chimney fabric using a combination of manual fabrication for the bespoke geometry and the SBPC1500 plasma cutter for the stack flange and stiffener preparation. The SB-ZF1500 continuous TIG stitchwelder runs the longitudinal seam on the inner liner for the vapour-tight construction.

Refrigeration plant ammonia duct routing — AS/NZS 60079 compliance

The ammonia refrigeration plant room duct routing on every major Australian seafood processor follows the AS/NZS 60079 Class I Zone 2 hazardous area construction. The duct material is 316L stainless throughout. The duct joints are bonded conductive to maintain electrical continuity to earth across the hazardous area envelope. The motor and damper actuator construction is IECEx Ex e or Ex d marked. The plant room emergency ventilation runs at 30 air changes per hour minimum under AS/NZS 1677. The wet scrubber discharge train handles the emergency release scenario. Continuous ammonia detection with two-stage alarm at 15 ppm and shutdown at 25 ppm. AS 4775 emergency eyewash and shower at every machinery room exit. The full ammonia compressor room safety envelope is the largest single AS/NZS 60079 compliance package on any Australian seafood processing facility.

Hot water plant — the sanitation and cooking demand

Seafood processing operates a substantial hot water demand for sanitation, for the cooking line (in canning and cooked-prawn operations), for the smoking kiln humidification (in hot-smoke salmon operations) and for the cleaning chemistry feed system. Daily sanitation cycles require 80 to 85 degrees Celsius hot water at multiple thousand-litre-per-day volume per plant. The hot water plant itself sits in a dedicated boiler room with combustion air supply, flue gas extract and emergency ventilation. The HVAC duct construction in the boiler room is galvanised G300 (acceptable in the dry mechanical environment) with the flue gas duct in stainless or refractory-lined construction depending on the boiler type. Heat recovery from the retort discharge water, the smoking kiln condensate and the compressor jacket cooling is increasingly standard practice on new Australian seafood plants and reduces the primary fuel demand by 20 to 40 percent depending on plant configuration.

Deep-frying breaded products — the mineral oil mist envelope

The value-added breaded seafood product lines — crumbed fish, breaded prawn cutlets, battered calamari and the various retail-pack frozen breaded specialty products — involve deep-frying in vegetable oil or specialty oil blends at 175 to 195 degrees Celsius. The deep-frying envelope generates a substantial mineral oil mist load that demands dedicated capture and high-efficiency particulate filtration before discharge. The HVAC duct construction is 316L stainless with continuous welded longitudinal seams, capture hoods over each fryer at 1.0 metres per second capture velocity, and a multi-stage filtration train (grease impingement filter, electrostatic precipitator, HEPA polish) before discharge through a roof-mounted stack at 1.5 metres minimum above the adjacent roof. Fire suppression under AS 1851 is mandatory in the fryer extract duct and the kitchen grease duct.

Pressurisation cascade — the AS/NZS 4674 envelope

The Australian fish and seafood processing pressurisation cascade under AS/NZS 4674 directs airflow from clean zones to dirty zones at all times. The standard six-step cascade for an AQIS export-licensed facility runs vacuum-sealed and MAP final pack at plus 25 Pascals, fillet trim and portion at plus 15 Pascals, IQF tunnel inlet at plus 5 Pascals, gutting and heading floor at minus 15 Pascals, offal and frame collection at minus 20 Pascals, and the rendering or fish meal processing zone if on-site at minus 25 Pascals. AQIS and DPIPWE auditors verify the cascade with calibrated micromanometers at routine audit. Sealed-seam AS 4254 Class B or SMACNA Class A duct construction is the minimum to hold the cascade. Leaky duct is the most common cause of cascade collapse and audit non-conformance.

Tasmanian DPIPWE biosecurity requirements

Tasmanian aquaculture operates under the Tasmanian Department of Primary Industries, Parks, Water and Environment (DPIPWE) biosecurity policy, which is the most rigorous aquaculture biosecurity framework in Australia. The policy covers pathogen exclusion (AGD, POMS, abalone viral ganglioneuritis), brood-stock and seed-stock movement controls, hatchery facility design including PC2 biocontainment construction under AS/NZS 2243.3, and the audit cycle that verifies compliance. The HVAC duct implication is the PC2 envelope construction in any hatchery zone where disease investigation is performed, the gas-tight isolation dampers at every penetration, the HEPA-filtered supply and HEPA-filtered extract, and the sealed-seam duct construction throughout. SBKJ supplies the PC2 envelope HVAC duct package on Tasmanian aquaculture hatchery projects with continuous TIG-welded seams using the SB-ZF1500 stitchwelder.

AQIS export licence framework

Australian seafood export licences are administered under the AQIS (Australian Quarantine and Inspection Service, now within the Department of Agriculture, Fisheries and Forestry) framework. The AQIS export licence covers the salmon export to Japan, Hong Kong, Singapore and the EU; the abalone export to Hong Kong and the Asian premium restaurant market; the prawn export to Japan, Hong Kong and the EU; the oyster export to Hong Kong and Singapore; and the canned seafood export to multiple Asian markets. The export licence audit verifies the duct envelope condition at every inspection cycle, with particular attention to the gutting line, the filleting line, the smoking kiln and the IQF tunnel duct construction. AQIS audit findings on duct construction non-conformance can suspend an export licence in 24 hours; the rebuild cycle to restore the licence typically runs 30 to 60 days depending on the scale of the finding.

HACCP for seafood — the construction implications

The Hazard Analysis and Critical Control Points (HACCP) system for Australian seafood under FSANZ 4.2.1 identifies the critical control points across the production flow and defines the construction standards required to maintain control. The HVAC duct envelope intersects HACCP at multiple critical control points — the IQF tunnel pull-down temperature control, the chilled holding temperature control, the smoking kiln temperature and humidity control, the canning retort sterilisation envelope, the Listeria monitoring zones above the cold-smoked salmon line, and the bivalve depuration cycle envelope. The construction implication is that the duct material, the longitudinal seam type, the cleaning access provision and the condensate drainage scheme all sit within the HACCP critical control framework and are audit-verifiable at every inspection cycle.

AS 1530.4 fire safety

AS 1530.4 governs the fire resistance testing of building elements including HVAC duct components. The smoking kiln chimney, the deep-frying extract duct, the cannery boiler room flue and the various combustion-adjacent duct runs all sit within the AS 1530.4 fire safety envelope. The duct construction has to achieve the rated fire resistance level for the building classification under the National Construction Code Volume One. Fire dampers under AS 1668.1 isolate the duct system at fire compartment boundaries. The integration of fire safety with the broader hygienic duct construction is a non-trivial engineering scope on every Australian seafood processing facility.

AS/NZS 2107 acoustics

AS/NZS 2107 governs acoustics for occupied spaces including the office and amenity zones of seafood processing facilities. The processing floor noise level under Safe Work Australia is managed by separate engineering controls (machinery selection, isolation pads, sound enclosures), but the HVAC duct contribution to noise in the office and amenity zones is governed by the AS/NZS 2107 background noise rating. Duct silencer specification, fan selection and air velocity calibration manage the noise contribution.

AS 3580 air quality

AS 3580 governs ambient air quality monitoring and the AS 3580 methods are applied at the discharge stack and the surrounding property boundary to verify state EPA Air Quality consent compliance. The rendering plant odour control, the fish meal cooker odour, the prawn offal grinder odour and the smoking kiln chimney discharge all sit within the AS 3580 measurement framework. The HVAC duct engineering on the odour control train, the discharge stack height and the dispersion modelling all support the AS 3580 compliance verification.

Cold storage and walk-in cold rooms

The cold storage envelope downstream of the production zones includes the walk-in cold room at 0 to 4 degrees Celsius, the chilled holding at 4 to 8 degrees Celsius, the walk-in freezer at minus 18 to minus 25 degrees Celsius, the blast freezer at minus 30 to minus 40 degrees Celsius and the optional cryogenic IQF tunnel at much lower surface contact temperatures with liquid nitrogen or liquid CO2 spray. Pre-insulated 316L stainless panel duct is the standard construction throughout. The vapour barrier is continuous on the warm side of the panel insulation. Penetrations are factory-foamed sleeves with butyl gasket seals on both warm and cold sides. Hangers are thermal-break to prevent heat bridging. Defrost cycle accommodation handles the periodic hot-gas or electric defrost on the evaporator coils.

SBKJ engagement model — from specification to commissioning

The SBKJ engagement model for an Australian seafood processing HVAC duct project follows a five-stage process from specification through to commissioning and after-sales support.

• Specification. Engineering review of the facility brief, zone-by-zone duct material and construction class recommendation, machine sizing against the production volume targeted, integration with the AS/NZS 60079 ammonia plant scope and the AQIS export licence or DPIPWE biosecurity compliance programme.
• Quotation. Itemised landed-cost worksheet on EXW Box Hill North or delivered-to-site basis, with machine specification, FAT scope, training scope and spare-parts package.
• Order and FAT. 30 percent T/T deposit at order confirmation, 70 percent balance against dispatch documentation. FAT run with buyer's 316L coil before dispatch from Box Hill North VIC.
• Installation and commissioning. 1 to 2 SBKJ engineers from the Box Hill North VIC office on site for 5 to 10 days for installation, mechanical commissioning, electrical commissioning and operator training in English. Coordination with the customer's HACCP and AQIS programme owner.
• After-sales. 12-month warranty from commissioning, one-year wear-parts kit shipped with the machine, 72-hour remote support response from Box Hill North, 10-year-plus parts continuity guarantee.

Talk to an SBKJ engineer about your salmon farming, ocean trout, abalone, oyster, prawn, tuna or seafood cannery facility brief, or your aquaculture hatchery expansion — we typically respond within 12 hours during Australian business hours. Contact SBKJ for an itemised landed-cost quote, or browse the full machines catalogue and the SBKJ Insights library for related guides.

The five highest-leverage decisions on a seafood processing HVAC project

Across hundreds of Australian and export-market seafood processing duct projects, the pattern we see is that the engineering scope is well understood — AS 4696, AS/NZS 4674, FSANZ 4.2.1, AS/NZS 60079 and the AQIS export licence compliance programme are all documented — but integration is where projects succeed or fail. The five highest-leverage decisions:

1. Specify 316L stainless throughout the production envelope from the start. The chloride load from continuous saltwater wash-down, brine glazing, coastal aerosol and chlorinated sanitation chemistry makes 304L untenable for any duct above an open product zone in Australian seafood processing. Get the 316L specification locked at design stage. The capex differential between 304L and 316L is 15 to 20 percent on the duct fabric cost line; the operating life differential is 4 to 6 times in favour of 316L. The capital decision pays back inside the first decade and removes the most common AQIS audit non-conformance source.
2. Document the AS/NZS 60079 ammonia compressor room scope thoroughly. Ammonia is the single highest-risk industrial gas in any Australian seafood plant. The Class I Zone 2 hazardous area construction, the 30 air changes per hour emergency ventilation, the wet scrubber discharge train, the continuous monitoring and alarm system, and the worker safety dossier are all critical. The Worker Safety case and the AS/NZS 60079 compliance dossier should be the first deliverable on the project.
3. Engineer the V-groove drip-tray construction on every horizontal duct run above open product. Condensate drip onto open seafood product is the most common AQIS export licence audit finding and the easiest one to engineer out at the construction stage. The V-groove drip-tray bottom profile costs incremental fabrication time on the SBAL-V auto duct line tooling and almost nothing on the operating cycle. Specify it on every fabricated piece in the production envelope.
4. Specify FAT at the Box Hill North VIC office on every machine and every duct package. Compromised FAT correlates strongly with post-installation disputes. The cost of a thorough FAT is one week. The cost of skipping it is a rework cycle measured in months. SBKJ runs FAT at the Box Hill North VIC office on every machine with the buyer's nominated 316L coil. The duct fabricator should run an equivalent acceptance test on the fabricated duct against the project specification before shipment to site.
5. Plan the cold chain commissioning around AS 4326 audit cycle. The cold chain from harvest receival to dispatch dock is the AQIS auditor's principal concern outside the production-zone hygiene scope. Thermal mapping at commissioning per AS 4326 with calibrated data loggers at minimum 12 points per zone for 48 to 72 hours; pressurisation cascade verification at every audit; defrost cycle verification at every annual recommissioning; loading dock cold chain integrity verification at every dispatch shift. Build the cold chain documentation programme into facility OPEX. The Spirit of Tasmania ferry transit and the Devonport-to-Geelong cold chain integrity is a particular focus for Tasmanian salmon, trout and abalone exporters.

Get an itemised SBKJ quote for your salmon, ocean trout, abalone, oyster, prawn, tuna or seafood cannery project →

FAQ

Why is 316L stainless steel mandatory rather than 304L?

Australian seafood processing combines continuous saltwater and brine wash-down chloride load, chlorinated and peracetic acid CIP sanitation chemistry, and aerosolised proteinaceous mist from gutting and filleting lines. 304L develops chloride pitting and stress-corrosion cracking within 5 to 7 years in this environment. 316L with 2 to 3 percent molybdenum confers chloride pitting resistance and the operating life is 20 to 30 years. AS/NZS 4674 and FSANZ 4.2.1 default is 316L for production-zone duct.

What is the ammonia exposure limit in an Australian salmon or prawn plant?

Safe Work Australia sets ammonia at 25 ppm 8-hour TWA and 35 ppm 15-minute STEL. AS/NZS 1677 governs the refrigeration plant design, AS/NZS 5149 the safety requirements, and AS/NZS 60079.10.1 the Class I Zone 2 hazardous area classification. The HVAC duct response is dedicated 316L stainless compressor room ventilation at 30 air changes per hour, wet scrubber on the discharge, continuous monitoring with alarm at 15 ppm and shutdown at 25 ppm, and IECEx Ex e or Ex d marked equipment construction throughout the Zone 2 envelope.

What pressurisation cascade does AS/NZS 4674 require?

Six-step cascade from clean to dirty: vacuum-seal and MAP final pack plus 25 Pa, fillet trim and portion plus 15 Pa, IQF tunnel inlet plus 5 Pa, gutting and heading minus 15 Pa, offal and frame collection minus 20 Pa, rendering or fish meal minus 25 Pa. AQIS and DPIPWE auditors verify with calibrated micromanometers. Sealed-seam AS 4254 Class B or SMACNA Class A duct construction holds the cascade.

How does the IQF tunnel HVAC differ between salmon, prawn and abalone?

Salmon fillet IQF at minus 30 to minus 40 degrees Celsius with 3 to 6 metres per second air velocity for 20 to 30 minute pull-down to minus 18 degrees Celsius internal. Prawn snap-freeze IQF at minus 40 degrees Celsius (or cryogenic LN2 for premium head-on shell-on product) with similar air velocity for 15 to 20 minute pull-down. Abalone IQF is less common in Australia because the dominant abalone product is live-export, but the freezing envelope follows the standard 316L stainless pre-insulated panel duct construction with vapour-tight seals and door air curtain integration.

What HVAC zoning does a salmon smoking kiln require?

Hot-smoke kiln at 60 to 90 degrees Celsius with 309 stainless inner liner and 304 stainless outer skin, uninsulated inner liner to drain creosote condensate, 30 degree minimum slope on horizontal runs, removable cleaning panels at 3 metre intervals, wet chemical or water mist fire suppression per AS 1851, discharge stack 1.5 metres minimum above adjacent roof per AS 1668.2. Cold-smoke kiln at 18 to 25 degrees Celsius with 304 stainless throughout.

What standards apply to canning retort hall ventilation?

Retort sterilisation autoclave at 115 to 125 degrees Celsius and 70 to 200 kPa overpressure. Saturated steam atmosphere in the retort hall during the discharge cycle. AS/NZS 1668.2 governs the building ventilation. 316L stainless duct throughout with welded longitudinal seams, external insulation in operator gallery zones, V-groove drip-tray construction on horizontal runs, capture hoods over retort discharge points at 1.0 metres per second capture velocity, building extract at 12 to 20 air changes per hour.

How is prawn offal grinder odour controlled?

Two-stage odour control train: 316L stainless duct from each grinder hood and offal hopper to a wet scrubber (sodium hypochlorite or sodium hydroxide scrubbing chemistry), followed by a biofilter polish. Discharge stack 1.5 metres per second minimum exit velocity, 1.5 metres minimum above adjacent occupied buildings. Regulated under state EPA Air Quality consent. AS 3580 ambient air quality monitoring at the property boundary.

What does the PC2 biocontainment envelope require in a salmon hatchery?

AS/NZS 2243.3 PC2 envelope: one-way airflow from clean to dirty, HEPA-filtered supply, HEPA-filtered extract, sealed-seam 316L stainless duct construction, gas-tight isolation dampers at every penetration, plus 15 Pascal pressurisation. Tasmanian DPIPWE biosecurity policy requires PC2 construction in any aquaculture hatchery zone where AGD or other notifiable disease investigation is performed.

What air quality monitoring is required at an abalone propagation hall?

AS 3580 ambient air quality monitoring in occupied zones. Workplace exposure standards under Safe Work Australia for dimethyl sulphide DMS (0.5 ppm 8-hour TWA from micro-algae production), ammonia (25 ppm 8-hour TWA from abalone biomass) and H2S (10 ppm 8-hour TWA). Dedicated 316L stainless overhead extract at 6 to 12 air changes per hour, capture hoods over algae production tanks at 0.3 metres per second capture velocity.

What is the lead time for a seafood-processing-spec SBAL-V in 316L stainless?

SBAL-V 316L stainless variant: 16 to 20 weeks from deposit to FAT-ready, plus 2 to 4 weeks domestic Australian dispatch from Box Hill North VIC. The 316L grade carries a 2 to 3 week premium over 304L because of mill scheduling. SBFB-1500 spiral 12 to 16 weeks. SB-ZF1500 continuous TIG stitchwelder 10 to 14 weeks. SBSF-1525 stitchwelder 10 to 14 weeks. SBPC1500 plasma cutter 8 to 12 weeks. SBLR-600 longitudinal seam welder 8 to 12 weeks. SBTF-1500, SBTF-1602 and SBTF-2020 spiral tubeformer range 8 to 12 weeks. SBKJ books production slots six months ahead for ARBS 2026 May Sydney attendance and the Tassal, Huon, Petuna, Yumbah, Clean Seas and Coffin Bay project pipelines.