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Stainless delivers the brew

Stainless steel has delivered the lifeblood for the evolving brewery operation  of one of Australia’s largest independent beer businesses.

Brick Lane was founded by 25 shareholders in 2017 with the vision to grow a sustainable, more inclusive, independent brewery focused on quality, flexibility, and sustainability. Delivering its own craft beer, ciders, seltzers and other drinks, Brick Lane extends its facilities to the wider brewing community, offering its brewing and packaging services to like-minded partners to encourage and support the growth of independent and craft beer in Australia.

Critical to Brick Lane’s success was the design and construction of a state-of-the-art brewery, combining global-leading technology with local stainless steel technical expertise and fabrication. Located in Victoria’s Dandenong South on a 5,000sqm site, Brick Lane partnered with German-based brewery equipment supplier BrauKon to deliver the original 50hL 4 vessel brewhouse in 2018, which was later expanded in  2020 with an additional 110hL 4 vessel brewhouse.

ASSDA Member and Accredited Fabricator Total Piping and Mechanical (TPM) was engaged both locally and by BrauKon to deliver the equipment installation and assembly, and process and service piping. TPM used 316L grade stainless steel to AS 1528 (Stainless steel tube and tube fittings for food processing and hygienic applications) pipe and fittings for the process pipework lines, and 304 grade AS 1528 stainless steel for the service pipework lines.

With most of the equipment supplied from Europe, the connections were delivered in DIN sizes, presenting some challenges in transitioning from DIN to locally sourced AS 1528 sized tube. TPM addressed this by supplying custom-made transition pieces.

TPM’s highly skilled team of welders performed all the hand welding of process pipework to AS/NZS 3992:2020 (Pressure equipment – Welding and brazing qualification), AS 4041:2006 (Pressure piping) and ASME Section IX (Boiler and pressure vessel code: Welding and brazing qualifications). TPM also deployed one of its specialised orbital welding machines on site which completed more than 2,500 welds alone. 

In addition, TPM completed the high-pressure steam installation, all of which were weld mapped, NDT and hydrostatically tested in accordance with AS 4041:2006. 

Brick Lane’s Head Brewer Jon Seltin said TPM’s quality in the pipe fittings and welding was exemplary. ‘Their approach to hand-selecting their labour force ensured workers with validated welding skills, experience, attention to detail, efficiency, and quality. In periods of high pressure and tight deadlines, TPM’s management and staff always remained courteous, positive, and practical, contributing to a great on-site culture.’

Brick Lane was the first Australian brewery to adopt thermal load wort boiling and crossflow filtration technology, reducing its energy and water usage, improving beer output quality and eliminating the need to use non-renewable filtration aids. With sustainability and efficiency at the forefront of its design, the brewery also houses a vapour condenser, which reclaims energy from steam produced during the brewing process.

2021 Major Cellar Expansion

A multi-million-dollar investment in equipment to expand the brewery saw the construction of a major cold-block rolled out in 2021, increasing the operation’s annual production capacity to approximately 20 million litres. The expansion saw Brick Lane further adopt world-leading technologies in yeast propagation, fermentation management, automated liquids handling, centrifugation, high-gravity brewing, thermal storage/energy recovery and keg packaging.

ASSDA Member and Accredited Fabricator Furphy Engineering was engaged to design, fabricate, test, and deliver thirteen stainless steel tanks, including ten 400hL beer fermenters, two 450hL bright beer tanks, one 610hL hot water tank, plus an upper-level stainless steel access platform system. 

Approximately 100 tonnes of stainless steel was used for the project, including grade 304 for the fermenters, bright beer tanks and access platforms, and grade 316 for the hot water tank. The material used was a mix of stainless steel sheet and plate from 2mm to 10mm, 250NB Sch40 and 300NB Sch40 pipe, and various sizes of AS 1528 tube. Stainless steel materials were supplied by ASSDA Members Atlas Steels and Vulcan.

The fermenters and bright beer tank were designed and constructed to AS 1210:2010 (Pressure vessels). The fabrication of the fermenters, bright beer tanks and hot water tank was undertaken using a plasma arc welding (PAW) process. PAW produces excellent weld quality with the introduction of minimal heat and with no removal of parent material required for weld preparation. This system was pioneered in Australia by Furphy Engineering in 2006, and today they operate five PAW machines for tank and vessel welding.

The cooling jackets on the fermenters and bright beer tanks employ Furphy Engineering’s Dimple-Q, a laser-welded dimple plate that delivers efficient temperature control and achieves brew cooling from the exterior. Dimple-Q is the only Australian made laser-welded dimple plate and is manufactured in-house by Furphy Engineering in Shepparton.

Jon Seltin said Furphy Engineering was an excellent local partner for the major cellar expansion, with the team proactively involved throughout the project cycle while seamlessly collaborating with other project vendors. ‘The quality of the supplied tanks was excellent and their on-time delivery during difficult COVID restrictions was critical for the overall success of the project. Their reliability coupled with their flexibility, quality design and fabrication capability are no doubt why they enjoy such a good reputation in their industry.’

TPM’s team of welders was brought back on-site to perform the mechanical installation of the Furphy Engineering supplied tanks. From the time of the original build through to the completion of the third cellar expansion, TPM has delivered more than 5,000 welds and installed over  5,000m of stainless steel tube.

Brick Lane continues to have its eyes set on the future, with its site well-positioned to grow with the Australian craft beer market while setting the benchmark for sustainability and efficiency in brewing.

This article is featured in Australian Stainless Magazine issue 75, 2022. 

The benefits of stainless steel for brewing

Australia is in a craft beer renaissance. The materials used in beer production has evolved over the years, and today, stainless steel is the material of choice and industry standard in modern brewing. Let’s look at some of the benefits...

Corrosion resistant

Stainless steels are excellent combatants of corrosion. This resistance to attack is due to the naturally occurring chromium-rich oxide film formed on the surface of the steel, which self-repairs in the presence of oxygen.

With the correct selection of alloys and application of good design principles and proper fabrication practices, stainless steel equipment will perform successfully. 300-series stainless steels are commonly specified in brewing equipment, and passivation is a chemical surface treatment that is often performed to enhance the steel’s corrosion resistance. The process removes contaminants and promotes the formation of the steel’s passive film.

Better taste

Beer ranges broadly in acidity and has live micro-organisms which can cause biofouling and biocorrosion in the tanks and fluid lines used in the brewing process. This can deliver a metallic taste in beer, even with tiny iron concentrations. Stainless steels’ corrosion resistance offers the best insurance against any unusual and unwanted flavours.

Easy to clean and maintain

Compared with other materials, stainless steel is a hygienic, low maintenance product that’s easy to clean and sanitise. Chemical cleaning is an effective method for maintaining stainless steel brewing equipment. Typically, both an alkaline wash (often sodium hydroxide based) is used to remove organic materials. It is followed by an acidic treatment with phosphoric acid (with a dash of oxidising nitric acid) or, increasingly in hard water areas, a peracetic acid formulation for mineral scale removal. Beerstone removal may require warm solutions.

It’s important to never use bleach on stainless steel! It can cause staining, pitting corrosion and permanently damage the steel’s surface and protective layer.

Durable and sustainable

Stainless steel delivers structural strength and integrity, and with a proper maintenance regime, stainless steel brewing equipment can deliver a lifetime of use. In addition, stainless steel is 100% recyclable and is actively repurposed without any significant loss of material quality.

Sleek good looks

Today, many breweries are opening their venues as a vibrant place to eat, drink and socialise. Its popularity has gained momentum in the Australian market with stainless steel brewery equipment and processes showcased as part of the patron experience, delivering style, substance, and aesthetics.

This article is featured in Australian Stainless Magazine issue 75, 2022. 

Blown away by stainless steel

For almost 30 years ASSDA Member AirEng has delivered customised, state-of-the-art stainless steel airflow solutions for a wide range of local and global industries including agriculture, mining, food and beverage and water treatment. 

AirEng continues to be a leading industrial fan specialist, providing businesses with steadfast solutions, employing leading edge technology, practical design, and robust construction. All AirEng products are proudly designed and manufactured locally in Australia at their production facility in Bayswater, Victoria, spanning over a 3.2-acre site. 

Industrial fans are used for various applications and unique industry needs. They are generally broken down into three different fan types, axial, mixed flow and centrifugal, all of which can be manufactured in stainless steel and up to a sizeable 5m in diameter. AirEng predominately manufacture their fans in grades 304L and 316L due to the material’s excellent corrosion resistant properties, which maximises product performance and quality where contaminants are present in the air stream. AirEng also manufactures components using duplex stainless steels, particularly in grades 2205 and 2507 for even more rigorous duties.

AirEng recently manufactured and installed two stainless steel centrifugal fans for Sydney Water to improve onsite odour management for their Cronulla Sewage Treatment Plant (STP). AirEng worked closely with their client, considering not only the application, but equipment reliability, longevity, operational efficiency, maintenance requirements and capital cost. The centrifugal fans extract foul air to four packed tower scrubbers which deodorise the air prior to release into the atmosphere. The fans were rated at 50,000m³/hr each and powered by 90kW four-pole motors. They featured a 1.2m diameter single inlet, single-width backward inclined laminar impeller, with an overall weight of 2.5t. This was manufactured from grade 316L stainless steel for its high level of material strength and efficiency. 

The fan shafts and casings were also fabricated from 316L for its excellent corrosion resistant properties, ensuring reliability for a long and lower maintenance working life. Stainless steel materials for this project was supplied by ASSDA Member, Vulcan.

Aeration is also a necessary process in wastewater treatment plants, adding air into wastewater to allow biodegradation of the pollutant components. Industrial fans are used to create strong pressure and efficient airflow to provide air in the aeration process. 

With the correct maintenance procedures, AirEng fans provide a long service life and are designed for a minimum 20-year service. All their products conform to AS 2936 Industrial fans – Determination of performance characteristics, BS 848 Fans for General Purposes and US Air Movement and Control Association Inc. AMCA210 and AMCA310 performance requirements. 

AirEng is constantly evolving its manufacturing processes and material applications to suit emerging industries, skilfully matching fan design to process requirements. Material choice in aeration equipment can make the difference to reduce carbon footprints and substantially lower life-cycle costs.

Stainless steel is the material of choice in industrial fan applications due to its strength, durability, and corrosive resistant properties, in turn, increasing bearing life and dramatically extending maintenance intervals. Choosing the right technology is vital, however correct material specification is crucial.

 

Photo credit: AirEng

This article is featured in Australian Stainless Magazine issue 75, 2022. 

Global Industry Supply Chain Pressure

Simon Pepper, Managing Director of ASSDA Member SILA Global, provides an important update on shipping and logistics in the Australian supply chain.

To say the last few years have been unstable, uncertain, difficult, and perturbing would be an understatement. The worldwide impact and far reach of industry issues experienced remind us that we truly are a global economy, and an event on the other side of the world can severely affect the Australian supply chain. We are not out of the woods yet. 

Problems that occurred last year with freight rates, space constraints, rollovers, port closures and other delays are beginning to pale in comparison to what is now occurring in the Australian domestic logistics landscape. I must add at this point, this is my current experience and point of view.

Now that ocean freight rates have started to fall further since the end of the Chinese New Year period, we have seen some additional shipping capacity enter the market, as well as a few new players. This is welcome news and has helped enormously in what was looking like another difficult year in shipping. However, as it seems to be in our current environment, there is always something that will throw a spanner in the works. 

At this point, it’s the lockdowns occurring in China due to their zero-Covid policy, which saw Shanghai locked down for almost the whole month of April. As you would expect, this caused worker shortages, truck shortages, factory closures, reduced manufacturing capacity and so on. Now the ripple effect remains to be fully realised however, in my opinion, many companies are waiting on stock from that region. Once the gates open, we may see a small peak period of increased rates and reduced space while the market sorts itself out and, providing there are no more issues with lockdowns, stability will begin to be seen. 

However, there is now some concern about what this may mean for the Australian domestic supply chain in June/July 2022, which is already under unprecedented pressure since late January. It seems that just when there is a small sign of improvement, something else comes along and it only gets worse. 

To give some background on the current state of the Australian supply chain, November 2021 through to January 2022 was unseasonably busy, especially in late December 2021. Around this time there was also a known incoming price increase of stainless steel which resulted in a lot of companies purchasing high amounts of stock. Meanwhile, other companies in different steel spaces have referred to the period as an ‘avalanche of steel’ also driven by low scrap prices. December 2021 and January 2022 saw cargo still arriving thick and fast however, most receivers were closed for the holiday break which started causing some backlogs, albeit not overly detrimental at the time. 

In late January 2022, cargo started moving well and we finally saw a light at the end of the tunnel until the Omicron wave hit causing the situation to spiral downwards very quickly. Five months later, certain areas in logistics have still not recovered. Between staff becoming sick and people having to stay at home due to close contact isolation policies, the logistics industry (as did others) took a very heavy hit between labour to unpack, drivers to deliver and administration staff to manage it all. Carriers reached out to labour-hire companies which were going through the same issues. 

Some small gaps were filled but that lead to under-experienced staff doing the work, leading to other issues and becoming a cycle. At the same time, the transport industry was hit hard, and end-receivers were as well. There were staff shortages at receivers where deliveries dropped from five to six loads a day down to one to two loads, which compounded the problems and added to the backlog. 

It became so congested that some transport and logistics companies put a stop on new work for a period. I am aware of some companies in Melbourne that declined to take on any new work for a time and that is still occurring months later as the issues ebb and flow. We also saw some of Australia’s largest logistics providers shut certain sites for short periods due to safety issues brought on by being over capacity and there was simply no more room to hold containers. Added to these issues are other problems such as significantly increasing costs of labour including administrative personnel and drivers, fuel, and equipment. All of these areas are in extraordinarily high demand. At the same time, there is high staff turnover occurring in the transport and logistics sector. Personally, I have not experienced this level of difficulty or depth of issues occurring in the domestic supply chain since the release of the Australian Border Force Integrated Cargo System (ICS) back in October 2005. To say it’s difficult and time-consuming is an understatement and staff in all facets are in the middle of the sandwich between transport, traders, customers, receivers, distributors, end-users and finally the consumer. 

This is a broad overview of the issues, and each state and port has its own additional problems. For example, the Trans-Australia railway line flooding which occurred in February and affected the east-west supply chain seems to have hit Fremantle harder than it has on the east coast. Then there were our more recent flood events on the east coast. All of this has a knock-on effect Australia wide in some way and once again these are broad examples but hopefully, you can see what I mean by ‘unprecedented’. 

As a result of this chaos, container detention is a huge problem. Most, if not all, transport company policies, including SILA Global, have stated that they cannot be held responsible for detention charges due to circumstances beyond their control. There are reports from the Freight and Trade Alliance (FTA) that “it is conservatively estimated that container detention charges alone are costing importers $500m per annum” and further reports “in terms of the current diabolical state of Australia’s Maritime Logistics System”.

We suggest that importers write to their nominated shipping lines and request assistance with additional free time or reductions in already issued detention invoices during this period of unprecedented difficulty. We are here to help and if you need any assistance composing a submission, please reach out. I would also point out that the Freight & Trade Alliance (FTA) are making submissions to the Productivity Commission on detention practices, and you can find further information on their website. We recommend requesting 21-days of free detention time. While this seems to be granted less and less these days, starting at this point may encourage shipping lines to provide their maximum allowable free time. These free time recommendations are to assist in mitigating any detention costs that may be incurred due to extended delays and the state of the industry. 

In conclusion, the global supply chain issues are here to stay – for now. We’re all in this together and everyone is, in one way or another, affected by the current industry climate. A message I keep sending out is to treat each other with kindness during this time as it’s been hard on everyone.

SILA Global has been operating since 2010 as a leading logistics company with an outstanding reputation for providing innovative solutions. Recognised as an Australian Trusted Trader (ATT), SILA Global operates worldwide, providing door-to-door logistics services for steel products, chemical hazardous and non-hazardous, ISO tank containers, FMCG, project and heavy-lift cargo, and more. 

 

 This article is featured in Australian Stainless Magazine issue 75, 2022. 

Kingsford Smith Drive

Stainless for the long run

Brisbane’s Kingsford Smith Drive upgrade saw Australia’s largest use of stainless steel reinforcement bar to date, transforming the structural performance of one of the city’s busiest roads.  

An initiative of Brisbane City Council and designed and constructed by Lendlease, the Kingsford Smith Drive upgrade involved widening the 7km road from four to six lanes between Theodore Street at Eagle Farm and Cooksley Street at Hamilton. This was achieved via a retaining wall built between 10m to 15m out into the Brisbane River. As a major road corridor, Kingsford Smith Drive links the Brisbane CBD to Brisbane Airport, the Port of Brisbane and residential and economic growth areas including Northshore Hamilton and the Australia TradeCoast region. Planning for future traffic volumes, construction commenced in 2016 to deliver increased road capacity and improved public transport, pedestrian and cycle facilities. 

Critical to the upgrade and structure was the extensive use of stainless steel. ASSDA Member Valbruna Australia supplied 800t of grade 2304/1.4362 Reval® stainless steel in 12mm, 16mm and 20mm stainless steel reinforcement bar (rebar), which was used in the tidal zone to 1m above the Highest Astronomical Tide (the splash zone) of the precast fascia panels and in the lowest of the precast cantilever panels that fell within the splash zone.

The Brisbane River is a tidal estuary, and duplex stainless steel reinforcement meets the service life demands of structures in a brackish water environment. Stainless steel reinforcing resists chloride attack and pitting corrosion, and when specified correctly, provides a minimum service life of 100 years in concrete, reducing life-cycle costs. Kingsford Smith Drive carries an average of 70,000 vehicles per day, and stainless steel rebar delivers confidence in the strength, durability and structural performance expected of critical public infrastructure. 

The scheduling, cutting and bending of the stainless steel rebar to tight precast tolerances was performed by Mesh & Bar. Furthermore, Valbruna supplied approximately 5,000 grade 2205 stainless steel terminator couplers, used to simplify rebar placement and create anchorage within the concrete. 

Stainless steel was also delivered in spades for various other components of the project, with ASSDA Member and Accredited Fabricator Stainless Engineering Services engaged for the fabrication and installation services. Forty-two road bridge expansion joints were fabricated in their workshop using 15t of grade 2205, 10mm and 16mm stainless steel plate, with material supplied by ASSDA Member Stirlings Performance Steels. The cantilever bridge deck was constructed in 40m long concrete sections, and the expansion joint fixings were countersunk and bolted insitu to deliver a continuous smooth surface. 

Additionally, Stainless Engineering Services delivered 1.5km of stainless steel top rails for the Lores Bonney Riverwalk, Kingsford Smith Drive’s riverside promenade. The riverwalk meanders from Bretts Wharf to Cameron Rocks Reserve and the top rail was specified to follow the flow of the river, presenting several challenges in its fabrication and installation. Furthermore, the top rail was specified to be delivered in 10m lengths. It was TIG-welded on-site using grade 316 stainless steel 150x50x5mm rectangular hollow sections (RHS) with a 600-grit finish supplied by Stirlings Performance Steels. Different methods were trialled to achieve the curve specified and conventional manual means were applied to bend the RHS in-between the posts.

Stainless Engineering Services fabricated the stainless steel spigots from 32mm plate to suspend and clamp the galvanised balustrade panels, as well as other various stainless steel components including planter boxes, rung ladders for sewer and drainage manhole access and cover plates at all expansion joints along the boardwalk.  

Stainless steel tube was also used for 300m of pedestrian and bike rails at Cameron Rocks Reserve, with material supplied by ASSDA Members Australian Stainless Distributors and Midway Metals.

With the Brisbane River at its doorstep, the use of stainless steel throughout the project has delivered several key benefits in ensuring the longevity of public infrastructure in a marine environment. Structural durability, corrosion resistance and visual appeal are just some benefits that stainless steel has contributed to the precinct’s improvement and development.  

Completed in 2020, the Kingsford Smith Drive upgrade has delivered up to 30% travel time savings for all vehicles, 7km of new and improved pedestrian and cycle paths, and enriched urban amenities and green spaces for locals and visitors.    



This article is featured in Australian Stainless Magazine issue 74, 2022. 

Stainless steel reinforcement

Standing the test of time

Stainless steel reinforcement (rebar) is increasingly being specified for its excellent corrosion resistance, long-term performance and economic benefits.

There are many advantages to using stainless steel rebar:

  • Excellent durability, fire resistance and structural performance.
  • Exceptional corrosion resistance in harsh marine environments, resisting chlorides and pitting corrosion.
  • Extended service life and reduced life cycle costs.
  • Minimal maintenance costs and therefore less disruption of service for refurbishment or replacement.
  • Easy to cut and bend, good weldability.
  • Cathodic protection is not required.
  • Reduced concrete cover, minimising costs and delivering a more lightweight, higher tensile structure. Cracks are less critical and concrete surface treatments are not required.
  • Supplied in accordance with ASTM A955 and BS 6744 standards, both of which require  confirmation of  a generic corrosion resistance test  by the manufacturer to meet specific strength levels.

Some history
Concrete is the most used material in infrastructure projects because of its properties, cost and availability. It has excellent compressive strength but very poor strength under tension. Cast iron and steel bars were incorporated into structures to form durable and strong reinforced concrete with the steel protected by the alkalinity of the concrete. Unfortunately, a combination of cost-cutting (poor quality concrete) and atmospheric CO2 carbonation led to the prevalence of concrete cancer with reduced service life and durability.

In the USA, multiple reinforced slab highway bridges suffered severe reinforcement corrosion and state authorities explored galvanising, epoxy coatings and cathodic protection in refurbishment and new programs. The UK Government had similar concrete corrosion problems at Birmingham’s Spaghetti Junction and research led to the 1990s revision of their BA 84/02 Design Manual for Roads and Bridges. The new code required stainless steel reinforcement around slab penetrations, in splash zones or wherever severe disruption would occur if carbon steel repairs would be required. It also permitted lower cover and wider cracks if stainless steel was used compared to the carbon steel requirements. In addition, it removed the requirement for surface diffusion barriers such as silane treatments.

Over the following decades this philosophy migrated into commercial buildings and non-government infrastructure. 

Why stainless steel?
When carbon steel corrodes, the oxides are up to 10 times the volume. This expansion will start cracks in the concrete and possibly surface stains. This allows more water, oxygen and chlorides to accelerate the steel attack, cause concrete spalling, further corrosion and potentially, structural failure. Stainless steel is inherently resistant to corrosion and, even if it is exposed to overwhelming chlorides in concrete, the pitting attack does not generate sufficient localised corrosion product to fracture the concrete. Despite the short-term attack of galvanised coatings in fresh concrete, galvanised reinforcement was trialled but did not offer sufficient long-term durability. Epoxy coated steel reinforcement suffered from handling and installation damage leading to concentrated attack at coating holidays. 

The solutions of cathodic protection (CP) and sacrificial anodes for carbon steel reinforcement can be effective. However, the reinforcement must be electrically continuous, the operation of the system must be regularly monitored, and periodic surveys are required to monitor the distribution and effectiveness of the CP. In a bridge designed for a 300-year service life, the monitoring costs would be significant.

The unfounded barriers to using stainless steel
Galvanic acceleration of corrosion?
Early on, there was significant resistance to specifying stainless steel due to the perception of the need for complete replacement of carbon steel. Connecting stainless steel to carbon steel corrodes the carbon steel but that assumes a near-neutral pH, i.e. about 7. Concrete is quite alkaline, i.e., pH>9.4, and in those conditions, the galvanic potential of carbon steel and stainless steel is about the same. Multiple laboratory and real-life tests have shown no galvanic acceleration of the carbon steel corrosion, even with quite significant levels of chloride contamination. Hence stainless steel can be used around joins in slabs, penetrations, at surfaces where diffusing water can evaporate and concentrate aggressive salts or where road or marine salts accumulate.

The Schaffhausen Bridge in Switzerland used about 15 tonnes of stainless steel rebar in areas subject to road salt, about 5% of the total steel use. This added less than 1% to the capital cost and delivered a 13% life cycle cost advantage over simple carbon steel for an 80-year life cycle.

Nearer to home, the McGee Bridge over the inlet in Hobart uses stainless steel rebar in the tidal zone (where the tides act  as a chloride pump) and carbon steel in the superstructure where chloride risk is low.

Misunderstanding of the chloride resistance of stainless vs. carbon steel
The widely accepted chloride limits for common stainless steels in near-neutral water are not relevant to the highly alkaline interior of a concrete structure. Figure 1 shows the results of multiple laboratory tests and uses chloride as a percentage of cement as a measure of corrosivity. The limited use of carbon steel in poorly cast (higher chloride penetration) and lower cement content (lower pH) is evident. What is surprising is that austenitic 304 or 316 (or their “equivalent corrosion resistance” lean or low alloy duplex grades) provide useful service in a wide range of conditions.

However, duplex grades provide double the 0.2% proof stress than their austenitic equivalent and the worldwide trend is to specify reinforcement at the higher end of the alloy grade strength.

Product forms and inspection
Bar, and bar with defined deformations, are specified with recommended sizes that do not always match hard metric dimensions. Stocked sizes depend on the specific supplier. It is typical that bars above about 20mm diameter are supplied in duplex grades to utilise the superior strength compared to austenitic grades. 

Bars are often coupled by screwed fittings or can be welded provided the heat tint is removed, preferably by pickling. It is essential that stainless rebar is protected during delivery and site storage. If adjacent carbon or galvanised steel requires cutting, the debris must not settle on the stainless steel. Figure 2 of four bars is for quality assurance of bar delivered after pickling to remove contamination and passivate the surface. The upper two bars have different levels of pickling but are acceptable. The lower two are not acceptable because of iron residue from the rinse water (C) and insufficient pickling time (D).

Pre- and post-tensioned cables have been mainly austenitic but the strength advantages of duplex grades mean they are increasingly being used. Stainless steel mesh is often used to control shrinkage cracking and deliver tensile strength. A further product form for inclusion in concrete (and refractory) are wire fibres which are either undulating or with end hooks and aspect ratios in the range 35 to 60:1. 

 

This article is featured in Australian Stainless Magazine issue 74, 2022. 

Stainless steel: Security, style, and functionality

Stainless steel mesh has combined form and function in a patient-centred design to deliver a safe, outdoor sanctuary for recovering mental health patients.

Ancient civilisations understood the critical importance of daylight associated with human health, happiness, and wellbeing. Today, there is increased interest in green architecture, with natural light and air becoming a significant design consideration. Studies suggest that light and nature should be strongly considered when building new medical facilities, because of their positive effects on recovery.

Austin Hospital in Melbourne’s north-eastern suburb of Heidelberg is a leading healthcare, teaching and research facility renowned for its specialist services in mental health and rehabilitation. A $15.2 million expansion of the hospital’s Short Stay Observation Unit and Psychiatric Assessment and Planning Unit in 2016 aimed to deliver dedicated mental health care to address the demand and growth of emergency department presentations.

The Short Stay Observation Unit was built above the ambulance bay and includes a lounge that opens up to an outdoor space filtered with natural light, fresh air and unobstructed views. Crimsafe’s Tensile-Tuff® stainless steel security mesh screens were specified for the enclosed outdoor area balustrading as the ultimate solution for providing exceptional strength, transparency and multi-faceted safety and security properties. Tensile-Tuff® Crimsafe mesh does not compromise on visibility or airflow and is well-equipped to deliver on aesthetic appeal with the structure also being the main feature of the hospital’s external façade.

Manufactured and delivered by Crimsafe, the commercial strength screens are made from 0.9mm, grade 304 stainless steel wire and were fabricated in a multitude of off-square angles to seamlessly match the structure. Fabricating with stainless steel mesh allows for limitless flexibility to marry safety with style and functionality. The material can be shaped in multiple planes without compromising on strength, while its clean lines and obstruction-free form allows for creativity in design.

All Crimsafe security screens are Australian made and meet or exceed the requirements for compliance with various Australian Standards. Crimsafe exceeds the 1.4 tonne requirement of AS/NZS 1170.2 (Structural design actions, Part 2: Wind actions) by three times the standard, load testing to 4.2 tonnes. In addition, the 1.5mm x 1.5mm aperture of the mesh filters up to 62% of UV radiation, minimising heat gains and delivering energy efficiency. 

Forty-one bespoke triangular Crimsafe security screens were manufactured and installed by Sydney-based licensee, Wynstan. Crimsafe’s exclusive Screw-Clamp™ bites down on the mesh, holding it into the frame, which is then secured by tamper-resistant stainless steel screws. This vice-like grip transfers any weight and pressure to the frame, so the mesh remains intact. The unit specifically responds to the need for fall prevention, protecting patients and minimising falls.

With the help of stainless steel, Austin Hospital’s state-of-the-art facilities exude strength, security and style, challenging the convention of mental health rehabilitation and recovery. Opened in 2018, the Short Stay Observation Unit continues to deliver a peaceful and safe space for patients.



This article is featured in Australian Stainless Magazine issue 74, 2022. 

Stainless steel water drainage

Australian innovation driving sustainability

For over 30 years ASSDA Member Stormtech has been at the forefront of Australian innovation delivering stainless steel linear drainage solutions for the local and global architecture and design industries.

Stormtech is an Australian family business that began operations in 1989 and was established on the invention of a special drainage grate. Founder John Creighton was approached by an architect to help design a hobless shower for a wheelchair-bound client wishing to shower independently. Creative thinking and innovative engineering led to the birth of a unique stainless steel drainage design that delivered excellent surface water removal efficiency while demarcating the wet and dry areas of a shower without a need for a hob or barrier. This design was adopted as standard, patented and is now Stormtech’s 65ARG slimline linear drain.

Today Stormtech continues to thrive, pursuing innovation and excellence both in the way it operates and services its customers, as well as through its commitment to sustainability. A world-leading business in ethical and sustainable practice, Stormtech showcase over 150 drainage products across a range of many different functions, from bathroom, pool and spa drainage to hospitality, commercial, and healthcare applications. Their linear drainage products range in widths from 65 and 100mm and lengths from 900 -3000mm, with eight architectural grate designs on offer. Custom drainage products are also delivered for specific applications and water flow efficiencies. 

All Stormtech products are Australian designed and manufactured at their New South Wales’ facility in South Nowra. Stormtech prides itself in an all-Australian supply chain, with all stainless steel drains fabricated from grade 316. Electropolishing, electroplating and powder coating services are offered through their local network of third-party suppliers, to deliver specific stainless steel specifications requiring coloured and other special surface finishes.

Stainless steel is a material of choice in linear drainage due to its strength, durability, low maintenance, safety, visual appeal and 100% recyclability. 

Grade 316 has excellent corrosion resistant properties, maximising product performance in coastal areas and pool installations, particularly where acidic soil may be present. Architecturally, stainless steel linear drainage offers an elegant and modern finish in addition to delivering a lower profile, creating an even, safe surface and seamless transition between indoor and outdoor areas. The material is also hygienic and easy to clean, complementing hospitality, health, and aged care applications. 

Stainless steel’s durability and sustainable properties coupled with Stormtech’s quality design and manufacturing has assisted designers and specifiers meet their environmental goals. In addition, it has provided solutions to overcoming poor drainage issues in construction, including ponding, which can undermine foundations and lead to structural and aesthetic damage.  

As part of the company’s Industry 4.0 journey, significant capital investment has enabled Stormtech to introduce state-of-the-art manufacturing equipment and develop software automation for business and sales support. Their CNC machine processing and design and drafting capabilities have significantly increased, delivering positive outcomes including a 0.3% scrap rate. All materials are XRF scanned for grade confirmation and stainless steel scrap and offcuts are reused or recycled. Stormtech’s sustainable commitments have also seen the company pioneer their own stainless steel fabrication techniques to eliminate the use of harsh chemicals. Ongoing R&D will also see the company continue to launch and introduce new capabilities, with sustainability at the core of its focus.

Stormtech was the first drainage business in Australia to gain sustainability credentials, maintaining its GreenRate Level A Gold certification with Global GreenTagTM since 2013. In addition, all products are WaterMark certified.


Standard TR Grate design with custom curve 
Photo credit: Stormtech

This article is featured in Australian Stainless Magazine issue 74, 2022. 

Raising the standard with stainless steel

Water quality plays a crucial role in the decontamination and reprocessing of reusable medical devices, and stainless steel has helped facilitate the standard required for their sterilisation. 

The release of AS/NZS 4187:2014 Reprocessing of reusable medical devices in health service organisations requires hospitals across Australia to comply with a range of stringent new requirements consistent with European and global standards for sterilisation processes. Its aim is to ensure reusable medical devices are adequately cleaned, disinfected and sterilised to protect patients and prevent infection.

Water quality is critical for sterile processing, and one requirement of the revised standard includes the replacement of non-compliant cleaning, disinfecting and sterilising equipment. There are minimum water quality requirements for pre-cleaning, cleaning and the rinse(s) prior to final rinsing. These include water hardness no greater than 150 mg/L and chloride no greater than 120 mg/L. AS/NZS 4187:2014 also specifies water quality requirements for the final rinse stages of sterile processing across Tables 7.2, 7.3 and 7.4, including final rinse water for manual cleaning and washer-disinfectors, and feed water for a dedicated steam generator.

Despite the Australian water quality guidelines, water supplies are variable in chemical impurities and the microbiological purity may also be a challenge. Therefore, water used for the final rinse of the disinfection process and the generation of steam for sterilisation must undergo treatment to achieve the water quality requirements. Reverse osmosis technology delivers a solution to meet the physical, chemical and microbial water quality required for the final rinse.

Reverse osmosis (RO) is a water treatment process that uses a semi-permeable membrane and applied pressure as the final step to filter out ions, unwanted molecules and large particles. The process is effective for the removal of micro-organisms and both organic and inorganic chemical components. ASSDA Member and Accredited Fabricator J&T Mechanical Installation have delivered stainless steel bioprocessing equipment for over 25 hospitals across Queensland, New South Wales and Victoria to meet the new specification and requirements of AS/NZS 4187:2014. The ongoing work includes the fabrication and installation of new equipment and replacement of non-compliant ring mains, water distribution networks and RO water treatment systems.

The RO water treatment systems must accommodate the required regular thermal disinfection to mitigate bacterial endotoxins and deliver a high level of microbial water quality. The treated water is reticulated to central sterile services departments (CSSDs) where surgical instruments and other reusable medical devices are sterilised. Continuous bacteria control is critical to supplying the required microbial water quality and the use of ultraviolet (UV) light in the ring mains to treat return water delivers compliance with AS/NZS 4187:2014. UV sterilisation is 99.99% effective in killing microbiological substances, and  is a safe, chemical-free process.

Stainless steel is the standard material of construction in water treatment applications, offering hygienic properties, durability, and optimum long-term performance. With excellent corrosion resistance and hydraulic conductivity characteristics, stainless steel is the first-choice material for best overall water system design.  

In addition, plastic materials are not viable in high water purity applications due to potential leaching, and copper may also be an issue because of cupro-solvency in soft water. 

Grade 316 stainless steel material has been specified for works as per the standard, including the use of 51mm tube, 20mm three-piece ball valves,  and 45o and 90o bends as specified in AS 1528 and supplied by ASSDA Member Atlas Steels.

J&T Mechanical Installation’s expertise has ensured the highest quality of work continues to be delivered to meet the current and future requirements of water supply systems complying with AS/NZS 4187:2014. Orbital welding is used on site during installation, with bioprocessing equipment requiring high quality welds to ensure water supply remains free of bacteria, rust and other contaminants. Orbital welding ensures full penetration welds with no overheating occurring that could undermine the corrosion resistance of the final weld zone.

The J&T team also performs hydrostatic testing and weld traceability to confirm mechanical integrity, as part of AS/NZS 4187:2014’s requirement for all equipment to undergo installation qualification (IQ), operational qualification (OQ) and performance qualification (PQ) tests.

As the roll out of AS/NZS 4187:2014 continues across Australia, hospitals and other health organisations are required to have a documented plan for implementation in place by December 2021, with the deadline for full compliance by December 2022.  Critical hospital infrastructure demands long-term compliance, structural integrity and quality fabrication, all of which are being delivered using stainless steel and superior workmanship by J&T Mechanical Installation.

  

Photo credits: J & T Mechanical Installation

This article is featured in Australian Stainless Magazine issue 73, 2021. 

Common misconceptions about stainless steel

Everyone knows that stainless steel resists corrosion, but beyond that, an amazing range of half-truths and exaggerations have evolved - often misleading and sometimes simply wrong. This article examines some of the more common myths, explains why they are wrong, and more to the point, provides correct information.

MISCONCEPTION: There are only two types of stainless steel, 304 and 316. 

FACT: There are hundreds of stainless steels from high strength duplex 2205 supporting bridges, to furnace ducts of ferritic 3/5Cr12 and the high temperature 310, but the most common types are the austenitic 300 series.

Stainless steels were invented a little over 100 years ago. The corrosion resistance, ease of cleanability, and bright appearance of stainless steels meant its compound growth since 1950 has been about 5% year-on-year. Because of the ease of forming and welding, about 70% of stainless steel use has been within the austenitic family. Within 30 years the accepted chromium level for good corrosion resistance settled at about 18% and “304” was born. Then stainless moved to the seaside and corroded, which led to the development of “316” by adding molybdenum. This in turn created the popular myth of two readily weldable and formable stainless steels despite the hundreds of austenitic grades recognised in standards.

About 25% of global use is seen in (mainly) thin sheet ferritics for cladding. The remaining 5% sees strong duplex, extra strong martensitic blades and wear resistance, and the precipitating hardening grades where strength/hardness is the priority.


MISCONCEPTION: 316 stainless steel is a marine grade and is suitable for seawater immersion. 

FACT: Seawater has about 20 times the chloride level that 316 can withstand and it is worse if the surface is rough or has a crevice (such as a nut and bolt). Seawater suitable stainless steels are the super austenitic or super duplex grades.

316 is often referred to as the ‘marine grade’ but this simply means that, provided it has a good finish and is washed by rain or under a proper maintenance regime, it will remain bright and shiny. In seawater it will rust especially around hard fouling or crevices – think seashells or bolts – and even under deposits in the splash zone. Furthermore, in severe coastal applications where salty ocean spray is allowed to build up over time, 316 can visibly corrode. 


MISCONCEPTION:  If it has rust stains, it is not stainless steel.

FACT: Carbon steel contamination or choosing the wrong grade of stainless steel are the usual reasons for rust on stainless steels.

If the rust occurs within a few days or weeks, it is almost certainly due to carbon steel contamination from fabrication or the local environment. Longer initiation periods arise from surfaces that are too rough, aggressive environments (think 304 posts on a wharf), lack of washing (drainpipes under eves) or bar product that has not been passivated. 


MISCONCEPTION:  Stainless steel reinforcement will cause accelerated galvanic corrosion of carbon steel reinforcement.

FACT: In concrete, carbon and stainless steels have similar galvanic potentials. 

Galvanic interactions occur between connected metals that have different potentials when immersed in a liquid that will cause one of them to corrode. Hence 304 bolts in a 316 panel immersed in tap water will not show galvanic effects despite the difference in potentials. In contrast, carbon steel will corrode more rapidly when coupled to copper or stainless steel in water. It is different in alkaline concrete as both stainless and carbon steel are at the same potential. It is common practice to use stainless steel reinforcement in tidal and splash zones or around penetrations and couple it to the rest of the carbon steel reinforcement.


MISCONCEPTION:  Only non-magnetic stainless steels have good corrosion resistance.

FACT: Magnetism is not related to corrosion resistance.

Probably because the lower chromium stainless steels are all magnetic, e.g., the 3/5Cr12 utility grades or the 410 or 420 or 440 martensitic, a myth perpetuated that magnetism and corrosion resistance were related. And then along came duplex grades with their resistance to seawater (and more aggressive environments) plus a strong ferromagnetic effect. The weak magnetic effect of heavily cold worked 304 versus the negligible magnetic effect of cold worked 316 may also have contributed to the myth.


MISCONCEPTION: Low nickel in stainless steels means it will corrode.

FACT: Nickel only affects the microstructure form, NOT corrosion resistance.

Nickel is a friendly metal and is the predominant influence in turning  ferritic stainless steel into austenitic or duplex grades depending on how much nickel is added. It has no effect on corrosion resistance to initiation of corrosion, which is how the integrity of stainless steel is judged.


MISCONCEPTION: Well-polished stainless steel does not require maintenance. 

FACT: Maintenance is important for the long-term effectiveness of any product. Stainless steel requires minimal maintenance but relies on preserving its passive film with oxygen and water.

Maintenance of stainless steel is required i.e., cleaning to remove adherent deposits left after rain washing. High polish will ease maintenance cleaning, but in the long term, general grime can accumulate just like the detritus on coatings or concrete.


MISCONCEPTION: Using a 316 nut on a 304 bolt stops galling of fasteners.

FACT: Austenitic stainless steels are widely used for corrosion resistant bolting, but galling control requires consideration beyond materials selection, including hardness, design and quality control, lubrication and friction.

Galling of fasteners is simply the cold welding of clean stainless steel surfaces under load. It is worse with fine threads, tight clearances, poor profiles, lack of lubrication, accumulated dirt and over-tightening. Because 304 cold works more than 316, the rule of thumb that a 50HB difference in hardness would prevent galling leads to the 304 cold rolled bolts and 316 machined nuts combination as a “solution”. It may work but the list of caveats above shows its limitations. 


MISCONCEPTION:  Stainless steel is expensive.

FACT: The initial capital cost of stainless steel material may be a few percent more but, when considering life-cycle costing, stainless steel delivers long-term performance with minimum downtime and low costs associated with maintenance.

Using stainless steel does not require coatings, has reduced maintenance requirements compared to repainting or patch repairs of coated or galvanised steel, and can either be repurposed or recycled after its practical life. For example, replacing galvanised steel with 304/316 stainless steel in one particular wastewater treatment plant reduced downtime for refurbishment or replacement from 22% to a mere 2%.

There is a stark contrast between the maintenance of iconic structures built from different materials. The Eiffel Tower in Paris was constructed in iron and Sydney’s Harbour Bridge is the world’s largest (wrought) steel arch bridge, but both structures require regular repainting as part of essential maintenance. New York’s Chrysler Building is clad in stainless steel and has only required two washings in its 90-year history. 

The Schaffhausen Bridge in Switzerland was built in 1995 with duplex reinforcement in the lower 7.6m of the pylons and 304 in the longitudinal reinforcement because of concerns about road de-icing salts. A life-cycle costing over 80 years showed that with stainless steel used for about 5% of the steel tonnage, stainless steel delivered 13% lower life-cycle costs over carbon steel.

Looking at sustainability, the Tokyo Water Authority reduced leakage in their potable water distribution system from 15.4% in 1980 to 3.6% in 2019 primarily by replacing mains to meter connections with corrugated stainless steel tube. To put this into context, since 1994 Tokyo has reduced annual water leakage by nearly 142 million cubic metres, with savings in excess of US$200 million per year. 


 This article is featured in Australian Stainless Magazine issue 73, 2021.

Rejuvenating stainless steel passenger railcars

1934 marked the birth of the world’s first stainless steel passenger railcar in the United States, and today it represents over 80% of all passenger railcars in Australia. Stainless steels deliver a sustainable materials solution for the rail industry, offering excellent physical properties including formability and weldability, in addition to its high strength, durability and aesthetic appeal.

The typical lifespan of a passenger railcar is 30 to 35 years, however with a proper maintenance program, stainless steel railcars can last more than 50 years. While only requiring minimal maintenance, dirt and other surface contaminants from daily use can affect the appearance of stainless steel.

ASSDA Member Callington Haven was recently engaged in Sydney to rejuvenate 20-year-old stainless steel passenger railcars back to their original aesthetic using a pickling process.

Pickling is a chemical treatment process applied to the surface of stainless steel to remove contaminants and assist in the formation of a continuous  chromium-oxide, passive film. 

The process leaves a slight matt finish and provides a passive surface immediately upon rinsing, maximising the ongoing performance, durability and corrosion resistance of stainless steel.

With a controlled application and wash down process in place, the stainless steel passenger railcars’ transformation was performed using Callington Haven’s own S-Weld SPS Pickling Solution.

Following pre-cleaning of the surface with a detergent, the product was applied with a roller to prevent atomisation of the pickling product. After 25 minutes, the solution was soft water blasted and excess pickling agent was removed with a squeegee. A full water blast using clean potable water and dry down of the stainless steel passenger railcars completed the process.

S-Weld SPS Pickling Solution conforms to ASTM A380 (Standard Practice for Cleaning, Descaling and Passivation of Stainless Steel Parts, Equipment and Systems) and has a unique red colouring, allowing operators to know exactly where the product has been applied or if it has been washed down properly.

Pickling solutions usually employ dangerous acids, therefore personal protective equipment was worn by all personnel. For environmental reasons, measures to ensure prevention of run off onto the ground from the application and wash down of the railcars was implemented.

Maintenance is key to preserving public transport and using a pickling process that only took 1.5 hours to perform, Callington Haven delivered an ‘as good as new’ end result for Sydney’s stainless steel passenger railcars.

You can view this story’s pickling process in action at www.youtube.com/watch?v=CV64kea2pBE

 
Photo credits: Callington Haven


This article is featured in Australian Stainless Magazine issue 73, 2021.

Bankwest Stadium - Stainless feeds the spectator appetite

Stainless steel continues to be the material of choice for commercial kitchen equipment, meeting and exceeding the rigorous demands of busy food service operations.

Dubbed as the ‘Home of Sport in Western Sydney’, Bankwest Stadium opened in April 2019 in the heart of Parramatta. The 30,000-capacity, multi-purpose rectangular stadium features a steep tiered seating arrangement across five levels, offering the best viewing quality of live events. Sport matches including rugby league, rugby union and soccer are some of the arena’s main events. To complement the unparalleled live event experience, the stadium’s clever design ensures spectators are never more than 30 metres away from onsite food outlets and amenities. 

The stadium features 16 food and beverage outlets, 11 kitchens and five bars. ASSDA Member and Accredited Fabricator Stoddart delivered a bespoke solution for the 32 food and beverage areas with the fabrication, supply and installation of an extensive range of stainless steel commercial kitchen and food service equipment.

The major kitchen fit outs by Stoddart included the supply of Halton ventilation exhaust hoods manufactured under license at their Karawatha site in Brisbane. Food service equipment supplied included commercial combi-steamer ovens, Adande refrigerated drawer systems and Anets deep fryers, brands exclusively imported and distributed by Stoddart in Australia.

Stoddart’s own Culinaire range of commercial kitchen equipment was custom fabricated, manufactured, supplied and installed. This included vertical and standard hot cupboards, bain-maries, hot food slides and cold food displays. In addition, wash basins, work benches, counters, shelves, wall sheeting and spine walls were also manufactured and supplied.

TIG welding techniques were used across the different goods and services provided. As an ASSDA Accredited Fabricator, Stoddart’s strong expertise in stainless steel design and fabrication ensured the strict requirements of food equipment manufacture were met. Correct surface finish, avoiding cross-contamination of materials, and hygiene and cleanability of stainless steel food equipment are some important considerations in delivering quality products expected to perform in busy food operations.

Overall, a significant amount of 304 grade stainless steel was used for the project, including 8,500m2 of coil, 3,987 linear metres of tube, 158 flat sheets (1.2mm thick, 914mm and 1219mm wide sheets in various lengths) and perforated sheets (1.2mm thick, 500mm wide in various lengths). Stainless steel coil and tube was supplied by ASSDA Member Dalsteel Metals, while the stainless steel sheet was supplied by ASSDA Member Midway Metals.

Stainless steel is a versatile and attractive material offering corrosion and heat resistant properties. It has  a non-porous surface, therefore it is less reactive and does not affect the taste of food. 

Commercial kitchens are the busiest places in the hospitality industry, and stainless steels meet the high-level standard for delivering excellent hygiene, cleanliness and durable equipment. In addition, stainless steel delivers a long service life of over 10 years for food service equipment and over 20 years for fabricated goods including exhaust hoods, benching and wall sheeting.

Bankwest Stadium is now a distinctive landmark for Western Sydney, and with the use of stainless steel, offers an exciting range of food options highlighting the flavours of local operators.

  
 
Copyright: Stoddart

This article is featured in Australian Stainless Magazine issue 73, 2021.


Terrigal Boardwalk - Stainless sets the scene

The seaside town of Terrigal on the New South Wales’ Central Coast has welcomed a new addition to its foreshore with a scenic walkway using stainless steel.

The long-awaited Terrigal Boardwalk connects the existing pedestrian networks of the Terrigal Beach promenade and The Haven, providing a safe and accessible route around the headland. The new attraction provides social, health and economic benefits for the local community, allowing visitors and tourists to enjoy the public space and ocean front area.

The project was jointly funded by the Central Coast Council ($2.9M) and the NSW Government’s Restart NSW Regional Growth Environment and Tourism Fund ($2.98M). The Terrigal Boardwalk’s construction included a restoration of the adjacent rockpool, a new disability-access ramp and pathway to link the rockpool and boardwalk.

Engineered and designed by Arup, the boardwalk structure has a 50-year design life, demanding a robust design to ensure durability and longevity. The elevated boardwalk is 277m long and 3m wide, and complements the surrounding natural environment with its blackbutt timber decking and stainless steel balustrading.

The construction comprises of a reinforced concrete suspended deck structure, a suspended structural steel viewing platform with fibre-reinforced plastic open mesh, sandstone block revetment and a retaining wall ramp structure. For the bridge deck, 7.5m is the typical span of the precast deck planks between concrete headstocks on steel tubular piles. Solid concrete deck planks were chosen to protect the timber boardwalk above from wave damage and minimise overtopping for users. The boardwalk sits approximately 4.5m above sea level to be just clear of wave crests during strong weather events.

Materials selection was critical to meet the specified design life, with consideration given to the foreshore’s high level weather events and salt exposure. Grade 316L stainless steel was specified for the balustrading on both sides of the boardwalk, ramp handrailing and the rock platform staircase.

While aluminium was considered during the design phase, stainless steel was chosen due to the material’s proven performance, corrosion resistance and durability in a marine environment, and aesthetic benefits in conjunction with the timber decking and handrail specified. In addition, a costing exercise conducted by Arup presented the long-term benefits of using stainless steel outweighing its additional upfront cost over aluminium.

Constructed by Land and Marine Group, the project involved a high level of collaboration between multiple local suppliers and service providers to meet the exacting demands of the specification. 

ASSDA Member Synergy Engineering was engaged to fabricate and install the stainless steel handrails, balustrades and stairs, spotted gum timber railing and the structural steel viewing platform. The project involved the stainless steel fabrication of 247 balustrade panels, 119m of handrail balustrade and an 8-step 1200mm wide staircase with fibre-reinforced treads. TIG welding techniques were used throughout the fabrication and installation process to ensure precision and a clean aesthetic.

ASSDA Member Atlas Steels supplied over 15t of 316L stainless steel, including 3402m of 30x8mm flat bar and 1656m of 70x10mm flat bar. The project was undertaken in the midst of the COVID pandemic, presenting a number of challenges with the supply of imported stainless steel material and shipping lead delays. As a result, Atlas Steels took the initiative to laser cut stainless steel plate to size and engaged ASSDA Member Decoware Australia to polish the material to specification. Starting with a coarse 80 grit through to a 400 grit finish, a surface finish of Ra <0.5 µm was achieved. The resourcefulness of local service and skill assisted in meeting the project program, delivering a resolution for the unprecedented challenges.

A small proportion of material was sourced from ASSDA Member Viraj Profiles, and ASSDA Member Vulcan Stainless supplied an additional 11t of laser cut 5mm, 10mm, 16mm and 20mm 316L stainless steel plate for the project.

Following fabrication, all stainless steel balustrade panels and handrails were electropolished by ASSDA Member Australian Pickling & Passivation Service and delivered directly to site for installation by the Synergy Engineering team.

The beautiful coastal boardwalk features a viewing platform, integrated seating, LED lighting and access to the rock platform. Offering uninterrupted views of the Pacific Ocean and beyond, the Terrigal Boardwalk is certain to meet the performance requirements of its design with its quality construction and use of stainless steel. 

The Terrigal Boardwalk officially opened on 14 April 2021, with its first steps taken by local crowds alongside the New South Wales Premier Gladys Berejiklian, Parliamentary Secretary for the Central Coast, Adam Crouch, Central Coast Council Administrator, Dick Persson, and the Council’s new CEO, David Farmer.
 
    

This article is featured in Australian Stainless Magazine issue 72, 2021.

Structural design of stainless steel

Stainless steel is used for a wide range of structural applications including:

  • Beams, columns, platforms and supports in processing plant for the water treatment, pulp and paper, nuclear, biomass, chemical, pharmaceutical, and food and beverage industries;

  • Primary beams and columns, pins, barriers, railings, cable sheathing and expansion joints in bridges;

  • Entrance structures, canopies, cladding and support systems for masonry;

  • Security barriers, blast walls, hand railing and coastal structures. 

Case studies of a range of structural applications are available at the case studies section of  www.teamstainless.org/resources/information-center-for-stainless-steel-in-construction.

This introduction to structural design in stainless steel aims to highlight differences between the material properties and structural behaviour of stainless steel and conventional carbon steel normally used for structural purposes, e.g. grade 350 to AS 3678 and AS 3679.

It should be noted that stainless steel structures should not be simply designed using design standards for carbon steel, such as AS 4100 and AS 4600, because of the significant differences between the mechanical properties of carbon and stainless steels.

Selection of an appropriate alloy of stainless steel is the first step in any design process.

Austenitic stainless steels are most widely used for structural applications, though the use of duplex stainless steels is increasing, where it is possible to exploit the benefit of high strength (around 460 MPa, compared to a strength of around 220 MPa for austenitic stainless steels). This can be particularly valuable in weight-sensitive structures like bridges or on offshore topsides. Duplex stainless steels are more likely to be used in heavier gauges. Ferritic stainless steels are also suitable for structural applications, offering a corrosion resistant alternative to many light gauge galvanised steel applications. They are generally used in gauges of 4 mm and below although the 12% chromium utility alloys are used in thicker sections (vehicle chassis or high temperature ducting) when minor rust staining can be allowed.

Material properties

From a structural viewpoint, the main property that distinguishes stainless steel from carbon steel is the stress-strain response. In contrast to carbon steel, for which the stress-strain curve may be modelled as bi-linear for most compression and flexural member design purposes, the stress-strain curve of stainless steel is generally highly non-linear and without a distinct yield point. Figure 1 compares the stress-strain characteristics of various stainless steels with carbon steel for strains up to 0.75% and Figure 2 shows typical stress-strain curves to failure. (The figures show stress-strain curves which are representative of the range of material likely to be supplied and must not be used in design.) The distinctive mechanical properties - considerable strain-hardening and ductility - make austenitic and duplex stainless steel particularly well suited for structures required to withstand accidental loading due to their high energy absorption characteristics.

In the absence of a clear yield stress, it is common practice to define an equivalent yield stress for stainless steel by using a proof stress, usually the 0.2% proof stress. (By definition, the plastic - or permanent - strain at 0.2% proof stress is 0.2%.) The proportional (or linear) limit of stainless steels’ deflection ranges from 40 to 70% of the 0.2% proof stress.

As a result of the non-linearity, stainless steel loses stiffness at low stress levels. This affects the design rules for members that rely on stiffness to transfer loads, notably compression members and unbraced flexural members.As well as nonlinearity, the stress-strain characteristics of stainless steel also display non-symmetry between tensile and compressive behavior and anisotropy, i.e. differences in behaviour of coupons aligned parallel and transverse to the rolling direction. In general, anisotropy and non-symmetry increase with cold work and so are more significant in the design of lighter gauge heavily worked sections, rather than thicker walled structural sections.

It is possible to enhance the strength of austenitic stainless steel by cold-working to a much greater extent than for carbon steel.

The initial modulus of elasticity (Eo) of stainless steel alloys is slightly lower than that of carbon steel.

The behaviour of stainless steel at elevated temperatures differs to that of carbon steel because of the metallurgical differences caused by the composition. Stainless steel retains a greater proportion of its strength at temperatures above about 550 °C and shows better stiffness retention at all temperatures, which is important in design against fire for components such as blast and fire walls.

The coefficients of expansion (CTE) of austenitic stainless steel alloys are larger than those of carbon steel. At the same time, the thermal conductivity is lower. While the CTE is important in determining thermally  induced stresses and deformations, the combination of larger coefficient of expansion and lower thermal conductivity has the effect of substantially increasing the risk and possible extent of welding distortions than those experienced in fabricating carbon steel structural member. The duplex grades have similar thermal conductivity to the austenitics but with 20% lower CTE so the risk of welding distortion is slightly lower than with austenitics. 

Specifications and reference documents for design of  stainless steel structures

American Society of Civil Engineers (ASCE) has revised ASCE 8 Specification for the design of cold-formed stainless steel, applicable to lighter gauge austenitic and ferritic material in the annealed and temper-rolled condition (Reference 1). The 2002 version has been substantially updated because of extensive research work and will be issued late in 2021. This includes alternative treatments of compressive loading, i.e. effective width and direct strength. The structure of AISC 8 will be familiar to those using AS/NZS 4673:2001 although 4673 has now been withdrawn as an aged standard.

Also in 2021, the American Institute of Steel Construction (AISC) will release a new standard (reference 2) AISC 370 Specification for Structural Stainless Steel Buildings to reflect the substantial increase in the use of heavy structural stainless steel sections. It includes hollow sections as well as welded, hot rolled and bar products. It will be accompanied by AISC 313 Code of Standard Practice for Structural Stainless Steel Buildings (Reference 3) and an updated 2nd Edition of the 2013 AISC Design Guide 27: Structural Stainless Steel.

The Eurocode for stainless steel design, EN 1993-1-4, covers welded, hot rolled and cold formed products made from austenitic, duplex and ferritic alloys, at room temperature and in fire (Reference 4). The Design Manual for Structural Stainless Steel (4th Edition) was published in 2017 and gives essential information needed by designers concerning alloy selection, durability, material properties, design rules and fabrication, in accordance with EN 1993-1-4 and other European standards (Reference 5). A Commentary explains how the design expressions in the Recommendations were derived and gives background information and references. Design Examples demonstrate the use of the Recommendations. Section property and member capacity software is also available, all aligned to EN 1993-1-4.

This Design Manual and these supporting design tools are freely downloadable from www.steel-stainless.org/designmanual.

This article has been extracted from the 2020 Australian Stainless Reference Manual, available for purchase at assda.asn.au

REFERENCES: 1. ASCE 8-02 Specification for the Design of Cold-Formed Stainless Steel Structural Members, SEI-ASCE 8-02.  \   2. AISC 370-2021  \   3. AISC 313-2021  \  4. EN 1993-1-4:2006+A1:2015 Eurocode 3. Design of steel structures. General rules. Supplementary rules for stainless steels.  \   5.  Design Manual for Structural Stainless Steel, SCI Pubilcation P413, The Steel Construction Institute, 2017 (available from www.steel-stainless.org/designmanual).



This article is featured in Australian Stainless Magazine issue 72, 2021.

Lighting up Chinatown

Stainless steel lanterns now adorn the streets of Melbourne’s Chinatown, celebrating the cultural character of the longest continuous Chinese settlement in the western world.

Chinese lanterns are a symbol of Chinese culture worldwide, initially used to provide light and later adopted for religious worship, decoration and celebration. Traditionally made from silk or paper, the City of Melbourne recently evolved the Chinese hanging lanterns featured on Little Bourke Street from cloth to stainless steel.

In extensive consultation with the Chinatown Precinct Association, the City of Melbourne and GHD (Structural Engineers) reimagined the classic lantern with a detailed design that preserved the traditional aesthetic while examining a number of considerations. 

Durability and product life cycle were strong factors to reduce maintenance and regular replacement of the lanterns. Strength-to-weight ratio and resilience to local weather conditions was also important, with the completed design required to stay below 7kg to be viable for use on the existing catenary lighting system.

ASSDA Member Draffin Street Furniture worked closely with the City of Melbourne to bring the design to life, assisting with the materials selection and manufacturability of the lanterns. Two prototype lanterns were installed at the corner of Heffernan Lane and Little Bourke Street to test the design and seek feedback from local traders and the Chinatown Precinct Association.

Powder coated aluminium was initially selected as the design material however, stainless steel superseded the specification primarily for its strength and the ability for a thinner section of material to be used (0.6mm stainless steel sheet vs. 1.22mm aluminium sheet). In addition, stainless steel offered a more sustainable solution with a 25-year design life and little-to-no maintenance.

The final design resulted in a 700mm wide by 500mm high spherical lantern made from 316 grade stainless steel, powder coated with a luminous, metallic red colour. In Chinese culture, the colour red symbolises good fortune and joy. 

The lanterns were formed using laser cut 0.6mm sheet, with each panel formed into shape and fixed to a central aluminium frame. The custom-designed lanterns were manufactured by Draffin Street Furniture, and stainless steel material for the project was supplied by ASSDA Member Steel Color Australia.

80 new permanent lanterns were installed on the existing catenary lighting system, which was originally manufactured and supplied with the assistance of ASSDA Member Ronstan Tensile Architecture in 2009. The linear grid catenary suspended from the street’s buildings uses 316 grade stainless steel rectangular frames spaced equidistantly to hold the grid form, while permitting the suspension cables to connect to buildings at different heights depending on the availability of structural connection points. Designed to enhance the character of the precinct with Chinese lanterns and other iconography, the decorative and functional stainless steel catenary lighting system continues to perform structurally 12 years on since its installation.

Installation of the new hanging lanterns was completed at the end of July 2020. Brought to life using local design expertise and stainless steel, the lanterns maintain its symbolic heritage and will continue to provide a festive welcome to visitors for at least the next 25 years.
       

Image: @rayofmelbourne for @cityofmelbourne

This article is featured in Australian Stainless Magazine issue 72, 2021.

Stainless steel ignites  luxury, style and warmth

ASSDA Member and Accredited Fabricator Southern Stainless have taken outdoor entertaining to a new level with their custom-designed and Australian made stainless steel gas fire pit.

Alfresco living is a strong part of Australian culture, and Gold Coast based Southern Stainless saw an opportunity to bring warmth and elegance to the outdoor space with the use of stainless steel. Starting the design process in 2015 and with over 18 months of research and development, a stainless steel gas fire pit was born, meeting both Australian Standards and gas regulations. 

Elegant and simplistic in its design, Australia’s harsh coastal conditions inspired the firepit’s construction. Grade 316 stainless steel sheet with a 2B finish is used to construct the sleek body, door and burner tray, and 1.5mm 316 stainless steel tube is used to assemble the burner and legs. The fire pit has a stainless steel burner mounted into an enclosure to accommodate toughened glass pebbles surrounded by safety glass. Gas filters through the pebbles and ignites fire, giving the appearance of a floating flame.

Southern Stainless’ fire pits are available in square and round models, and measure 1m x 1m or 1m diameter. Both are fitted with two flame failure devices that automatically shuts off the gas if the primary pilot blows out. The flame failure devices provide additional safety while also making the fire pit extremely effective in windy conditions.

The fire pits have an LPG bottle compartment or can be designed to be plumbed into gas. In both instances, the fire pit comes with the gas controls and burner fully assembled. Only the glass safety sides need to be installed along with the toughened glass pebbles. If configured to be plumbed into natural or LPG gas, the appliance can easily be connected by any qualified gas plumber, or if ordered with an LPG bottle compartment, no installation is required.

Stainless steel is the clear material of choice when considering the great Australian outdoors. Grade 316 stainless steel has excellent corrosion resistance properties with an increased ability to resist pitting and crevice corrosion in warm chloride environments when compared with grade 304. It resists rusting in virtually all architectural applications, and is a durable, heat resistant and aesthetically appealing material option.

Stainless steel fire pits are built-to-last and combine physical warmth with visual luxury, offering year-round ambience to cater for the way of Australian outdoor living.


 

This article is featured in Australian Stainless Magazine issue 72, 2021.

 

A new twist on stainless design

With a striking and innovative design evoking visions of the Singapore based Helix Bridge, stainless steel has formed an integral part in creating one of Sydney’s most exciting new structures.

Commissioned by Landcom as part of the Lachlan Line Precinct development project in North West Sydney’s Macquarie Park, the yet to be officially named cyclist bridge provides visual flair, safe accessibility, and excitement to the area. In an area with typically heavy traffic congestion, the project’s promotion of reduced car dependency creates a significant positive impact to the surrounding environment.

The design is the first of its kind in Australia, utilising a double helix arrangement with a varying diameter along its curving 178m length. While the design elements certainly lend themselves well to aesthetics, structural requirements dictated much of the overall shape. A steel truss arrangement is used, required for the long sections spanning the multiple roads below its footprint. The diameter of the spiral increases at the bridge supports and tapers along its span.  At its narrowest, it is 5.5m in diameter, and 7.8m at its widest.

Approximately 170t of 2205 grade duplex stainless steel was used, along with around 220t of structural mild steel. Due to the large quantity of material required, multiple distributors supplied material mostly on an indent basis, with some delivered ex-stock. ASSDA Members Midway Metals, Stirlings Performance Steels and Vulcan Stainless all supplied material, with the majority of plate (up to 80mm in thickness) produced by ASSDA Member Outokumpu, managed through their Melbourne office. 

A minimum 100-year service life with minimal maintenance (becoming increasingly common in the design of bridges) was a key criterion, particularly important for the hard to access structural components. From the beginning, 2205 duplex grade presented as an ideal material, thanks to its hybridised microstructural properties granting it superior mechanical properties to many forms of mild and stainless steel. 

Put simply, being stronger allows for thinner sections to be used or, alternatively, more scope for efficient design such as larger spanning or increased resistance to bending moments. Mild steel was retained  for the helical outer structure, and painted blue, which was a central design requirement. 

Arup proposed duplex stainless steel for the deck structure and wearing surface within the helix due its increased strength to weight  properties whilst maintaining high durability performance.   

Outokumpu played an instrumental role in advocating the use of the material properties of duplex grade at the early design and concept stages. Backed up by global materials experts and with a wealth of expertise in supplying stainless materials for bridges all over the world, Outokumpu aimed to provide a technical solution through the use of duplex stainless, rather than simply tender for the supply of material. “The use of duplex stainless steels in bridges around the world is becoming more and more the material of choice, so it was great to see Arup in Australia embrace it in its design”, said Con Logos, Vice President APAC at Outokumpu. “A special thanks to George Miech from my team for his tireless effort in the early stages, working closely with both Arup and RMS to have duplex stainless specified”. 

Outokumpu also assisted the fabricator and the end client, Transport for NSW, with expertise, advice, and preliminary procedures in welding the material, particularly vital with the thicker sections which require great care to ensure optimal material properties are realised in the weld and adjacent areas.

The bridge was fabricated in Sydney in four modules, which were trial assembled prior to being delivered to site, where the four segments were positioned and secured over the course of four weekends. Specially designed lifting assemblies were necessary to ensure the segments were not overstressed. 

As bridge design increasingly demands greater durability, aesthetic and creative licence and structural performance, stainless steel, of the duplex family in particular, presents a wonderful option now and into the future.

Photo credit: Landcom

This article is featured in Australian Stainless Magazine issue 71, 2021.

 

Comparisons of hot and cold formed stainless steel

When comparing hot and cold formed stainless steel, the first question you would ask yourself is: are there any chemical differences between the two? ASSDA has previously published articles on the various surface finishes including the few hot and multiple cold finished processes, however this article concentrates on the differences. 

Since the 1970s, most stainless steel is produced by melting in an Electric Arc Furnace (EAF) and then the molten stainless steel is transferred to an Argon Oxygen Decarburisation (AOD) vessel or, less commonly, a Vacuum Oxygen Decarburisation (VOD) vessel. These processes control impurities such as carbon, sulphur, nitrogen, hydrogen and other impurities which could form oxide precipitates. For critical applications such as aerospace or precipitation hardening alloys, further refining is possible, but this is a smaller market. Critically, in AOD, using the injection of inert argon as the stirring agent into the melt allows control of nitrogen additions, e.g., for duplex or high austenitic stainless steels.  

Chemistry

The basic chemistry of a specific grade of stainless steel is the same regardless of how it is subsequently shaped, i.e., as hot or cold rolled, hot forged, cold drawn/shaped or simply cast –  with the proviso that cast stainless steels typically have more chromium and (often) more silicon than their wrought counterparts. In addition, even if cast products have been stress relieved, their microstructure is dendritic so that there can be significant composition differences (localised differences in corrosion susceptibility) between the early solidifying dendrites and the final bulk solidification.

Hot formed

Producing hot formed stainless steel is deceptively simple as shown in the graphic. Currently, for about 95% of production, the molten metal is decanted from the AOD into a cooled continuous caster and emerges horizontally as a slab. The microstructure in the slab is columnar from the outsides (because of the cooling by the caster walls) with a relatively uniform equaxial microstructure in the centre. It is also covered with heavy black oxide scale with a chromium deficient layer underneath – as with weld tints. Typically, the slab is then surface ground to remove solidification features and the scale which would both otherwise be incorporated into the surface during subsequent rolling. The slab is then charged into a reheating furnace and hot rolled to homogenise the microstructure and provide either plate or coil as the product form. The grains will now be more oriented along the rolling direction. The microstructure is then further refined (and internal stresses reduced) by annealing above 1000oC.

Unless the steel is to be used where appearance and maximum corrosion resistance is not critical, e.g., in a furnace, then after hot rolling it would be shot blasted to break up the scale and then pickled. The pickling causes the dimpled appearance of a Hot Rolled Annealed and Pickled (HRAP) plate surface because the pickling acid attacks the base metal at the defects in the black oxide scale. It also gives a typical surface roughness of 5 or 6 µm Ra. There is a potentially cosmetic corrosion issue if the (typically) fast pickle does not completely remove any shallow intergranular oxide penetrations, however this is unusual. For long product such as angles or channels, another visual distinction is that the edges meet at 90o compared to the radius of curvature determined by the thickness and ductility of a cold rolled product.

Cold formed

Cold rolled flat product is quite different because it usually starts at room temperature with a dimpled surface and finishes with thinner material – and watching the increase in speed of the sheet as it gets thinner is quite startling. There is a significantly more elongated microstructure along the rolling direction, and this enhances the anisotropy in transverse to longitudinal strength compared to the relatively slight effect for hot rolled material. Long product is not cold rolled but more correctly it is cold  shaped or formed.

The increase in strength with cold work can be substantial, especially in thin materials as the cold work increase can enhance the strength of the full depth. As an example, the table from ASTM A666 data shows the substantial change in mechanical properties for 304 from annealed to half hard, i.e. half the absolute maximum possible strength – which would have negligible ductility.

Effect of cold work on strength and ductility of 304

One effect of the increase in strength with cold work is that the limit of proportionality will increase with cold work, i.e., the linear deflection occurs up to a higher stress. The reduction in break elongation is simply reflecting the proof stress closing on the tensile stress from 40% to 73% as shown below.

Variation of thickness tolerances for cold and hot rolled materials

There are also differences in the tolerance between cold and hot formed material as shown by comparisons in A480 (flat product – sheet vs. plate) and A484 (sections). However, it is not as simple as “hot formed is less precise than cold formed” as seen below. 

Surface finish

Often it is important to consider appearance and corrosion resistance to the “bright and shiny” benchmark. Hot rolled material is always going to be dimpled, even when it is electropolished and exhibiting a brilliant lustre. It will be marginally more difficult to clean than a smoother cold rolled surface but abrading the surface to give a roughness of less than 0.5 µm Ra is counterproductive. You lose the passive stainless steel and an abraded surface potentially has sulphide inclusions exposed compared to the original pickled, sulphide free HRAP surface.

The inherent roughness of a cold rolled sheet decreases steadily as the plate is rolled thinner as shown in graph. It shows the decrease of Ra from the crushing of the peaks left from the hot rolling as the sheet gets thinner. The graph is for cold rolled annealed and pickled (2B) material and is useful when someone asks for a 2B finish for a thickness not in the band. However, thickness of pickled materials is not relevant to the corrosion resistance whereas the Ra is critical to an abraded surface both for reasons of cleanability and possible crevices from torn surface flaps plus, if not passivated, exposing sulphide inclusions.

 

This article is featured in Australian Stainless Magazine issue 71, 2021.

 

Award-winning stainless food plant

World-class processing systems demand high quality products, innovative features, and long-term yield increase, all of which have been delivered through superior workmanship, engineering, and the use of stainless steel.

ASSDA Member, INOX Australia, was engaged by a Melbourne based stock and soup manufacturer to design the integral process, fabricate, install, and commission a beef, chicken, seafood, and vegetable stock processing system. The processing system is entirely fabricated in stainless steel as it has been essential to the project design and fabrication, being the material of choice in demanding hygienic environments that involve high heat. 

Exceeding their client’s expectations, INOX supplied a processing system that provided multiple innovative features, winning the 2019 Food & Beverage Industry ‘Innovative Technology of the Year’ Award, and being nominated for ASSDA’s 2019 Fabricator Project of the Year Award. This extraordinary processing system features a single user operational interface, safe and ergonomic handling of the product during the process from start to finish and hygienic design of the process including zero wastage at end of production. It also improved the yield of raw materials by pressure processing instead of traditional atmospheric process.

The system works by depositing 1000kg of raw materials into a stainless steel basket which is lifted by an electric hoist into the automatically opened pressure vessel. The touchscreen operational interface is used to set and supply the water volume. The process is fully automatic to the set parameters and then alarms when the process is completed. Following the cooking procedure, the CIP (Clean In Place) water is circulated through the heating jacket of the vessel which serves two purposes. The first is to cool the cooking vessel to a temperature that allows the product to be discharged, and the second, to use the heat recovered from the cooking vessel to heat up the cleaning water. This reusable use of heating allows for no external heating of the cleaning water.

The liquid stock produced is then pumped through a specially designed filtration system, to a holding tank which is then ready for the product to be received by the external filling line. The stainless steel basket is then removed from the vessel and the waste product is dumped into a hopper underneath the basket, ready to be removed to a disposable waste bin. The basket is then cleaned within the vessel during the CIP process and does not exit the food processing room at any point, ensuring the equipment is cleaned and cannot be contaminated externally. 

An impressive 5000kg of 304 and 316L grade stainless steel was used to complete the project. All stainless steel material was supplied by ASSDA Members, Midway Metals, Vulcan Stainless and Tubesales Stainless. This included stainless steel tube, pipe, plate and sheet with 3mm to 12mm thickness. Several components (with thicknesses up to 75mm) required a large amount of specialised machining. The material was mechanically polished where required to achieve a better than 0.8 µm Ra surface finish. This superior material of choice meets the project’s sanitary requirements, offers structural integrity and excellent corrosion resistance in high temperature applications. 

 

This article is featured in Australian Stainless Magazine issue 71, 2021.

 

Stainless steel – a mainstay in water assets

A mainstay in the processing of sewage water in water recycling applications, stainless steel once again plays a critical part in working towards a sustainable future.

Western Water Treatment Plant (WWTP), south of Werribee in Melbourne’s Western District, is a critical asset responsible for processing around half of the city’s total sewage. The process requires a massive footprint, where a series of large lagoons use anaerobic (without oxygen) and aerobic (with oxygen) bacteria to sequentially break down and clean the feed water of solids and gases. The resultant recycled water is used for multiple non-drinking purposes, including irrigation and firefighting. 

WWTP is also largely energy self-sufficient. This energy is captured during the sewage treatment process by combusting biogas, which is captured under the covers. Biogas is used to meet much of the Plant’s electricity needs – preventing hundreds of thousands of tonnes of carbon dioxide entering the atmosphere each year. 

The site carries significant environmental importance to both the immediate and wider areas. Biogas production from the process is used to meet all the Plant’s energy needs through on-site power generation. The Plant is an enormous site – almost the same size as Phillip Island and a world-renowned wetland, declared a Ramsar site in 1983. It is home to many species of flora and fauna and a haven for birdwatchers – in summer it can host more than 100,000 birds in a month.

With current capacity concerns in the existing plant network, stretching back 120 years, and a forecasted increase in processing demands due to a growing city, the need for an additional nutrient removal plant (to complement the existing two) was established. More efficient in design and with more advanced monitoring and controls to provide class A recycled water, the new plant provides an additional 140ML of treated water per day. The plant was designed by Jacobs and built by UGL and CBP Contractors, with commissioning in 2019.

Grade 316L stainless steel was selected as a default material for the pipework, in 2B finish. Offering strong corrosion resistance even against contaminated effluent water, its ease of fabrication and ability to be installed without the need for coating and subsequent maintenance was also important.

ASSDA Member and Accredited Fabricator Roladuct Spiral Tubing was selected to manufacture and supply approximately 50t of spiral welded large diameter pipe, ranging from 300 to 1422mm in diameter. Feed material was supplied  by ASSDA Member, Midway Metals to Roladuct’s  Melbourne manufacturing site. 

Roladuct was nominated in 2019 for the ASSDA Fabricator Project of the Year Award, with judges impressed by the quantity of stainless steel used, as well as the significant environmental benefits realised by the plant upgrade.

As water assets continue to be upgraded and optimised for a growing country, stainless steel will continue to play a vital role in providing material performance and plant reliability for years to come.

 

 Photo credit: Roladuct Spiral Tubing

This article is featured in Australian Stainless Magazine issue 71, 2021.