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Riverwalk Reborn

21 October 2014

Brisbane's New Farm Riverwalk is one of the city's beloved icons. Originally constructed in 2003, the Riverwalk was used daily by over 3000 cyclists, pedestrians and runners before it was washed away during the 2011 floods.

After a construction period of nearly 18 months, Brisbane City Council’s re-imagined New Farm Riverwalk has now opened to the public, connecting New Farm to the Brisbane City via the Howard Smith Wharf Precinct.

Engineered by Arup, the Riverwalk has a design life of 100 years and sits 3.4m above mean sea level on robust piles.

Critical to its design and life expectancy is the extensive use of stainless steel for both structural and aesthetic purposes.

Brisbane City Council’s two key objectives of the project were to achieve a low maintenance, durable structure while achieving high aesthetic qualities. Stainless steel was deemed suitable to achieve both objectives while also providing the necessary strength required.

Key design elements featuring stainless steel include balustrades, skate stops, help point enclosures, light posts, signage, electrical enclosures, deck furniture and bins at the node structures. For additional durability, stainless steel reinforcement conforming to BS10088 and BS 6744:2001 was used in the soffit of the precast concrete girders where the structure could be subject to wetting and chloride contamination in the future.

Constructed by John Holland, the project involved a high level of collaboration between multiple suppliers and fabricators to meet the exacting demands of the specification.

John Holland Project Engineer Cameron Pahor said one challenge was programming works in accordance with project specifications to reduce contamination between carbon steel and stainless steel, both of which were used within the precast concrete girders incorporated into the Riverwalk.

Modelling of the reinforcing in 3D by Vectors Computer Aided Drafting also meant exact dimensions were ascertained, reducing waste of stainless steel reinforcing.

ASSDA Sponsor Valbruna Australia Pty Ltd’s Queensland construction division was contracted to supply 385 tonnes of stainless steel reinforcing bar, with The Australian Reinforcing Company (ARC) sub-contracted to schedule, cut and bend the rebar in a specifically prepared quarantine location to prevent processing and storage contamination issues.

Valbruna Special Products Manager Scott Ford said the majority of the rebar (in diameters ranging from 12mm to 40mm) was produced to precise precast tolerances predominantly using Reval® special Grade AISI 2304 (1.4362). Grades 2205, 316L and 304L were also used due to the unexpected increase in tonnage required: nearly 40% more than original project calculations was required, making the Riverwalk the largest use of stainless steel rebar in Australia to date.

Mr Ford said stainless steel rebar ensured the Riverwalk met the required 100 years life cycle, while minimising ongoing maintenance costs.

“Using stainless steel rebar ensures that a landmark structure such as the Riverwalk is kept open to the public rather than lengthy maintenance closures due to corrosion issues,” he said.

Down time was also minimised during construction, with Valbruna holding extensive stocks on the floor in both Italy and Australia of stainless Reval® rebar, enabling delivery to site within 48-72 hours of final approval of drawings. Manual templates were produced for many of the bars to ensure the accuracy of the bends and eliminate site down time.

Minimising maintenance for the visual elements of the Riverwalk was also a priority. To this end, ASSDA Sponsor Midway Metals supplied 275 tonnes of grade 316 stainless steel and two tonnes of welding consumables for the construction of around 1900m of balustrading. Midway also supplied 100 litres of Avesta pickling gel that was used to passivate all welds on the balustrades.

Midway Metals Brisbane Branch Manager Sean Lewsam said some of the specified handrail sizes were not available in Australia (e.g. 150x50x6mm rectangular hollow section or RHS) and had to be air freighted in to meet strict deadlines.

Midway supplied the project with 3,522 metres of RHS, 14,500 metres of round bar, 1,924 metres of HRAP (hot rolled, annealed, pickled) flat bar, 1,500 metres of flat bar from their slitting and flat bar machines, and 2,000 metres of mirror tube, storing the material in a dedicated holding area for the duration of the project.

Specific-sized Grade 316 plates were acquired (132 tonnes in total ranging from 10mm to 16mm) to minimise off cuts and wastage during the plasma cutting of stiffener plates, 1500 base plates and 1000 staunchions for the balustrades. Around 26 tonnes of laser cut profile plates ranging from 5mm to 20mm were also supplied.

ASSDA Member Southern Stainless was contracted to fabricate and install three different types of balustrading (solid uprights, mesh wire and glass infill), as well as the other visible stainless steel elements of the project using the stainless steel and welding consumables supplied by Midway Metals.

Southern Stainless General Manager Matthew Brown said all stainless steel components were manually polished to a 600 grit finish prior to assembly and welded in compliance with AS1554.6. After fabrication, the 960 balustrades panels (each weighing between 180 and 220kg) were electropolished in-house to Ra<0.5 and then hand polished with silicone-based polish prior to being wrapped and delivered to site for installation. The end product is both visually appealing and certain to stand the test of time.

Strength testing was undertaken for the balustrade/girder connections to ensure the stainless steel couplers, bolts and ferules (supplied by ASSDA Member Ancon Building Products) would not damage the cast-in items during a flood occurrence.

Riverwalk’s robust design makes it resilient to future flood events. The opening span has been relocated to reduce the likelihood of debris getting caught on the structure, and some elements have been designed to collapse in extreme events (rather than withstand the flood waters), reducing the force on the piles.

With the re-imagined Riverwalk now a fixture on the Brisbane’s riverscape once again, residents and visitors can look forward to enjoying the unique experience that Riverwalk offers well into the future.

This article is featured in Australian Stainless magazine issue 54, Spring 2014.

Stainless Steel and Nickel - 100 Years of Working Together

19 November 2012

This is an abridged version of a story that first appeared under the same title in Stainless Steel Focus No. 07/2012.

The Nickel Institute's director of promotion, Peter Cutler, and consultant Gary Coates, reveal some of the reasons for the continuing popularity of nickel in stainless steels.

Stainless steel is everywhere in our world and contributes to all aspects of our lives. We find stainless steel in our homes, in our buildings and offices, in the vehicles we travel in and in every imaginable industrial sector. Yet the first patents for stainless steel were issued only 100 years ago.

How did this metal become so desirable over the past century that more than 32 million tonnes was produced in 2011? And how does nickel, a vital alloying element in most stainless steel alloys, contribute to the high demand for stainless steel?

THE 'CREATION' OF STAINLESS STEEL
By definition, a ‘stainless’ steel has a minimum level of about 10.5% chromium, so the discovery of chromium in 1799 by Nicolas Louis Vauquelin in France was the first key event in the creation of stainless steel. In 1821 another Frenchman, Pierre Berthier, published research that showed a correlation between increasing chromium content and increasing corrosion resistance, but the high carbon content of his alloys prevented them from showing a true ‘stainless’ behaviour.

Still in France, in 1904 Leon Guillet first published his metallographic work on alloys that today would be classified as ferritic and martensitic stainless steel. In 1906 Guillet published his work on the nickel-containing austenitic stainless steel family, but his studies did not include corrosion resistance. Albert Portevin then continued to build on Guillet’s work.

In 1911, a German scientist named Philip Monnartz reported that as the chromium content neared 12% in a steel with a relatively low carbon content, the alloy exhibited ‘stainless’ properties. Further developments then rapidly occurred in many other countries. In the United States, Elwood Haynes started working with martensitic alloys while Becket and Dantsizen were developing a ferritic stainless steel as lead-in wires for electric light bulbs. In 1912, Great Britain’s Harry Brearley worked on a 13% chromium martensitic alloy, initially for high temperature service in exhaust valves for aeroplane engines.

Meanwhile in Germany, Eduard Maurer and Benno Strauss were testing nickel-containingalloys and, in 1912, two patents were awarded. One of these grades, containing about 20% chromium and 7% nickel, was called V2A, and was found to have exceptional corrosion resistance in nitric acid. That grade had a relatively high carbon content compared to today’s stainless steel, and would be
similar to a Type 302 (EN 1.4317) stainless steel. 100 years later, the most commonly used alloy for nitric acid is 304L (EN 1.4307) with approximately 18.5% chromium and 8.5% nickel, quite similar to the V2A composition other than having a much lower carbon content.

Brearley’s martensitic stainless steel alloy would not rust when wet. He worked with Sheffield cutlery manufacturers to forge it into knife blades and then harden it, replacing the carbon steel blades they were then making. Stainless steel knives rapidly became a common household item. However, for forks and spoons, where high hardness was not so important, the 18-8 (302) composition became the most commonly used alloy.

300 SERIES
We normally think of the austenitic or 300 series family of stainless steels as the ‘nickel stainless steels’, but many other families contain nickel. One of the prime reasons for using nickel in the 300 series alloys is that nickel is an austenite former, but other reasons include:

  • Nickel adds corrosion resistance, especially in certain aqueous environments, and in certain high temperature environments.
  • Nickel can retard the formation of embrittling intermetallic phases at elevated temperatures, a major downfall of the non-austenitic families.
  • The austenitic structure can mean high toughness at cryogenic temperatures.
  • The advantages of the 300 series extend to welding and forming operations.

A fuller discussion of these topics can be found in 'The Nickel Advantage - Nickel in Stainless Steels', available on the Nickel Institute website.

200 SERIES
The 200 series stainless steels are also austenitic in structure. The standardised 200 series grades, which have chromium contents close to the level of a 304L alloy (about 18%), have an intermediate level of nickel. The ‘non-standardised’ 200 series not only have lower contents of nickel, but also lower contents of chromium, with the net effect of significantly reduced corrosion resistance, although still an improvement over the 11-13% chromium ferritic stainless steels.

DUPLEX
The duplex (austenitic-ferritic) family of alloys also need some nickel as well as nitrogen to ensure proper austenite formation. Most ‘matching’ duplex filler metals are actually over-alloyed with nickel to ensure that the welds have the required properties.

PRECIPITATION HARDENABLE
The precipitation hardenable (PH) stainless steel family contain nickel, which increases their corrosion resistance, ductility and weldability compared with hardenable non-nickel-containing stainless steel alloys. One of the other major advantages of the PH grades is that, unlike the martensitic grades, they do not need a quenching operation, which considerably reduces risk of distortion. Some of the martensitic grades also contain a small nickel addition. In the higher chromium types, the nickel is needed for the martensitic transition. In all nickel containing martensitic grades, nickel improves their corrosion resistance, ductility and weldability.

Some of the lower alloyed ferritic grades such as UNS S41003 (EN 1.4001) and S40975 contain a small intentional nickel alloying addition that allows for grain size control, which aids especially in welded constructions. A few of the higher alloyed ferritic grades also have a small nickel addition to increase toughness and ductility, which is beneficial during both hot rolling and in their end use.

Clearly, it is important for each specific application to select the appropriate alloy or alloys to give the desired properties.

GROWTH IN DEMAND FOR STAINLESS STEEL
According to the ISSF, 300 series stainless steel still dominates the worldwide production figures, as shown in Figure 1.

The properties of the various 300 series grades - created by the addition of nickel - are clearly valued by users, both in industry and the general public. Upwards of two thirds of all stainless steel produced in 2011 fell within the 300 series and close to three quarters of all stainless steel produced contains nickel.

The growth of worldwide production of stainless steel over the past 100 years has been steady, if not spectacular. This has meant that the demand for new nickel has steadily increased along with the demand for stainless steel, as shown in Figure 2. Recycled stainless steel is also a very important component in the alloy supply chain.

EFFICIENCY AND 'GREEN' CREDENTIALS
Resource efficiency is a recurring theme as the global economy faces economic challenges. Stainless steel not only contributes towards efficiency in many applications, it also shows continuous improvement in the resource efficiency related to stainless steel itself.

There are three important factors:

  1. Stainless steel’s long service life, which might average 15 to 20 years, although much longer in prestigious buildings.
  2. The extent of recycling: The percentage recovered and recycled at end-of-life - around 90% - is amongst the highest of all materials. Moreover, this recycling can be repeated many times without loss of quality. While the recycled content may appear to be relatively low, this is simply a result of stainless steel’s long service life (15 to 20 years) coupled with much lower global production 15 to 20 years ago.
  3. Continual production improvements for stainless steel and its raw materials. For example, whilst the ores being processed today are of lower grade than before, the extraction and recovery processes are more efficient.

THE FUTURE
The history of stainless steel would be incomplete without celebrating the extent to which it has enabled innovation not just in the area of improved performance, but also in the more intangible, aesthetic aspects. From chemical plants to medical equipment to iconic stainless steel-clad buildings, stainless steel has made - and will continue to make - a major contribution to almost every aspect of our lives.

With durability, recyclability, versatility and aesthetic appeal at the core of its appeal, stainless steel - with nickel as one of its trusted alloys - is well placed to continue to innovate and expand its applications.

STAINLESS STEEL IN USE

FOOD AND BEVERAGE INDUSTRY
The popularity of stainless steels in kitchens did not go unnoticed in the food and beverage industry.

If we take milk, we know of an early stainless steel bulk milk tank truck from 1927 in the USA. A paper entitled ‘The Corrosion of Metals by Milk’ from the January 1932 Journal of Dairy Science by Fink and Rohrman states: ‘It has long been known that milk in contact with iron and copper will not only acquire a metallic taste, but corrode these metals readily’. At that time, tin-coated metals were commonly used. It went on to say that ‘High chromium nickel (18-8) iron alloys … are very resistant to corrosion by milk and are satisfactory for dairy equipment …’. The modern milk processing industry is filled with stainless steel equipment, mostly of Type 304 (EN 1.4301) or 304L.

The report also went on to state that some materials that are otherwise suitable for processing of milk ‘…do not stand up well to the action of cleaning compounds that are commonly used in dairies’, but that the 18-8 alloy was suitable for those cleaning compounds. Today, the typical cleaning acids and hypochlorite sanitising compounds that are used not only in the dairy industry but also in most food and beverage plants worldwide, require that same 18-8 alloy as a minimum. A correctly chosen stainless steel alloy will not change the taste or appearance
of the food product. However, it is the ability to withstand repeated use of the sanitising chemicals over the lifetime of the equipment that has led to the widespread use of stainless steel in all sectors of the food and beverage industry. Producers are then able to guarantee the
safety of their food products.

ARCHITECTURE
Another area of quick acceptance was in architecture. The first recorded use for that purpose was in 1929 in London at the Savoy Hotel where a sidewalk canopy and a sign were erected with the 18-8 alloy. These were soon followed by two iconic skyscrapers in New York that used stainless steel as a dominant element on their exteriors: the Chrysler Building in 1930 and the Empire State Building in 1931.

Since then, many prestigious buildings around the world have used stainless steel, including the Petronas Tower in Kuala Lumpur, the Trump Tower in Chicago, and the Jin Mao Tower in Shanghai. Related to architecture is sculpture, and Isamu Noguchi convinced the Associated Press in 1940 to approve stainless steel instead of bronze for his sculpture above the entrance to its building in New York. Since then, artists around the world have been using stainless steel, mostly either 304L or 316L (EN 1.4404), in their works. The St Louis Arch in the USA, Frank Gehry’s Peis (Fish) in Barcelona, Spain, and more recently Genghis Khan in Mongolia are examples of what can be done with stainless steel.

TRANSPORTATION
During the Great Depression in the USA, Edward Budd realised the untapped potential for stainless steels. Although their use in aeroplanes was his first application, his legacy remains the building of more than 10,000 passenger railcars, some of them still in use today.

Around the world, stainless steel is used extensively for passenger rail cars for subways, commuter trains and long distance trains, ensuring safety plus long life and low maintenance costs. In addition, stainless steels are used to transport cargoes such as food products, petroleum products and corrosive chemicals by rail, road, water and even air, both domestically and internationally.

ENERGY
In the broad field of energy, stainless steels have been used to extract oil and gas containing hazardous substances as well as for use in the refining stages. For power plants, stainless steel is used extensively at both low and high temperatures, whether the fuel is coal, oil, gas, uranium or waste products. Hydroelectric stations use stainless steel for dam gates as well as turbines. Many of the established sustainable
energy technologies such as solar and geothermal are using stainless steel, as well as the present biofuels industry with corn or sugar cane as feed stock.

WATER
Fresh water is an essential commodity for mankind, and stainless steel is used extensively in treatment plants for potable water as well as for wastewater. Cost effectively producing fresh water from seawater or brackish water by desalination also requires the use of stainless steel. In some countries, underground stainless steel pipe is used to deliver potable water to homes to prevent leakage, or in other special cases to protect either the environment outside the pipe or the water inside the pipe. Stainless steel plumbing is also common in certain countries and offers a long lasting, low maintenance option.

SURGERY
The first recorded example of an austenitic stainless steel surgical implant is from 1926. Medical instruments are also known from that time period. The ability to easily and repeatedly sterilise components that come in contact with the human body or are used in hospitals and clinics contributed to the early acceptance of stainless steel. Today, there are well-established international specifications for materials used in this industry. For example, stainless steel alloys for implants must meet stringent metallurgical cleanliness requirements and be completely non-magnetic so that the patient can safely undergo diagnosis by Magnetic Resonance Imaging.

FUTURE USES OF STAINLESS STEEL
Strong growth in the use of stainless steel has continued in the past decades despite the rapid and diverse developments in other materials and the more recent economic turmoil. The nickel-containing alloys in the 300 series still account for nearly two thirds of current stainless steel production worldwide, and there is nickel in the 200 series, duplex and precipitation hardening families, as well as in some of the martensitic and ferritic alloys. The reason for this is the great value that is placed on the properties which nickel provides.

Society is rapidly evolving and facing challenges on a global scale. Population is increasing, expectations are growing and resources are limited. Therefore we must use those resources more efficiently. This is particularly apparent for energy where stainless steel, and especially the nickel-containing alloys, already plays a major role in the more difficult to extract fossil fuels. Stainless steel’s corrosion and heat resisting properties are key to more cost-efficient operations. This also applies to the renewable sources that are now being developed, such as wave power and biofuels from new organic sources.

The worldwide need for higher quality, safe food and beverages and water will only increase, especially as food products can come from anywhere in the world. Stainless steel has evolved as the material of choice in this industry, both industrially and domestically, and it is likely to continue to meet the demands of a global population that is predicted to increase to nine billion by 2050.

This growing population, combined with a rapid movement to urbanisation, requires an expanded and more efficient transport infrastructure. The characteristics of stainless steel enable it to deliver lightweight and durable designs, leading to more efficient performance, safety, lower energy requirements and reduced emissions while giving lower life-cycle costs.

Image of Trump Tower (Chicago, USA) pictured above courtesy of C.Houska.

This article is featured in Australian Stainless magazine, issue 52.

The Sustainable Score Card for Stainless Steel

9 December 2011

The greatest challenge we face is the control of our own success. With 7 billion people on earth, all with an insatiable appetite for a high standard of living, the newest dimension of materials competition is sustainability.

Sustainability is development that meets the needs of the present without compromising the ability of future generations to meet their own needs (UN World Commission on Environment and Development, 1987). In real terms, that means making choices that do minimum damage to our environment, but support a high level of human development.

The built environment is an excellent place to start. Buildings last for a long time, locking up the energy used in making their materials, requiring maintenance and consuming the energy used for heating and air-conditioning. They consume a large proportion of our resources. The choice of materials affects all 3 aspects of consumption, and, a number of building evaluation systems have been created around the world to assist in rating buildings for sustainability. Materials are scored for their energy content reuse during major refurbishment, waste management, recycled content and contribution to the overall design and running costs.

The Green Building Council of Australia rates green buildings for sustainability. The pace of registration and certification is increasing. Of the 368 certified projects, 96 were certified in the last 12 months. The push towards sustainable development in the building sector is strong and accelerating. City of Melbourne’s Council House 2 (CH2) is Australia’s first Green Star rated building to be awarded 6 Stars, which carries an international leadership status. Stainless steel was used to support screening walls of living green plants that shade the building and, required no maintenance or painting, working with the environment to keep good working conditions. Such membranes, containing plants or actively or passively screening the sun, allow the use of a smaller capacity air-conditioning plant, with lower capital costs and ongoing running costs and energy demand.

The only Gold LEED® (Leadership in Energy and Environmental Design) certified meeting venue in the world is the Pittsburgh Convention Centre in the United States. Its grade 316 stainless steel roof is used to harvest rainwater, reducing water demand on th

e city system - another example of the special properties of stainless steel.

Stainless steel roofing and rainwater goods give extremely low levels of run-off. See Table 1. But this is not the only reason to use stainless steel in the built environment. It contributes to sustainability because of its long service life, excellent corrosion resistance, clean and unchanging appearance and its exceptional hygiene characteristics. Stainless steel is reusable, entirely recyclable, and probably the most recycled product in the world. On top of that, it needs very little cleaning or short or long term maintenance, and makes no contribution to indoor pollution as materials emitting volatile organic compounds (VOCs) do.

There is considerable history and experience of stainless steel service life in the built environment. The Chrysler Building (1930) and Empire State Building (1931) in New York demonstrate the material’s durability, excellent appearance and resistance to corrosion. This extraordinary functionality has been played out many times with a number of examples here in Australia, including the Fujitsu Building in Brisbane, which is clad with 445M2 ferritic stainless steel. Located in a marine industrial environment, this building looks as good as it did on completion in 2002. The long life of stainless steel in these atmospheric applications shows its very high corrosion resistance. The corrosion rate of grade 316 for instance in most atmospheres is is more than 5000 times slower than the rate of carbon steel. See Figure 1 (below).

There is a considerable industry devoted to the collection and recycling of stainless steel products at the end of their life and, scrap is the standard feedstock for making stainless steel. In any stainless steel object, there is an average of 60% recycled content. New production would virtually all be made from recycled stainless steel if it were available, but the growth in the use of stainless steel and its long life in service limit the supply. Table 2 compares the recycled content and end of life capture rate of the industrial metals, and demonstrates that stainless steel is the most recycled industrial metal.

Sustainability is about much more than recycling. The energy used to make the material has a direct impact on sustainability, and all metals are energy intensive. Energy is a scarce resource, generates greenhouse gases and creates specific demands on land use likely to impact on future generations. Longevity and extraordinary recyclability will not be helpful if stainless steels’ energy consumption is much higher than other materials. Figure 2 describes the embodied energy in terms of CO2 equivalent for some of the industrial metals, and shows that stainless has a comparatively high level of embodied energy. In kilogram of CO2  per kilogram of metal, the austenitic grades are over double the footprint of carbon steel, although the ferritic grades are a little less. The footprint of stainless steel is caused by the production of alloying elements nickel and chromium, which are needed to give stainless steel its special properties, including extremely long life. Even so, efforts are ongoing in the stainless steel industry to reduce the energy content.

But in the real world, kilogram CO2  per kilogram metal comparisons are misleading. Take a typical application; a box gutter on a building. The metals have different strength, so are used with different thickness. Stainless steel gives a relatively light weight gutter (see Table 3), and hence the lowest footprint as installed. Coupled with its extended durability without maintenance, stainless comes out as the most sustainable option. Painted galvanised or Zincalume® coated carbon steel has not been included in the table as the calculation of the contributions of the components were too complex, but these materials are highly unlikely to beat the sustainability of stainless steel, even as-installed, and they have a much shorter life.

In summary, stainless steel has excellent recyclability, energy content as-installed (at least as good as other metals), extraordinary longevity and next to no need for maintenance, ever. Add to that the benefits of their special properties, which allow for the construction and operation of buildings at a lower cost. The contribution of stainless steel to sustainability is obvious and considerable.

This article was prepared by ASSDA Technical Committee member, Alex Gouch from Austral Wright Metals.

This technical article is featured in Australian Stainless magazine - Issue 50, Summer 2011/12.


Posted 5 January 2001

A special grade of stainless steel is being used in an Australian-developed environmentally friendly energy production method.

Solid oxide fuel cells extract the energy from fuels such as natural gas by electrochemical rather than traditional combustion means. producing cheaper, cleaner and more convenient eledricity.

lnterconned material made from half to one millimetre thick SAS 'Self Aluminising Steel' sheet conneds individual fuel cells together, conduding eledricity and heat within the fuel cell stack. The fuel cells are the brainchild of Melbourne-based company Ceramic Fuel Cells Limited and have been in development for eight years.

Managing Diredor, Ceramic Fuel Cells Limited, Dr Bruce Godfrey said stainless steel was the most suitable interconned material in terms of performance and produdion.

"Because the fuel cells operate at 800°C we need high temperature steels that can withstand the rigours of increasing temperatures and the fuels that we put into them," he said.

"Stainless steel in this respect fitted the bill perfectly for the stage of development we are at.

"The material has also proven very efficient during the prototype - development stage because it can be laser cut to size rapidly."

The special grade of stainless steel was chosen because of its superior performance in stopping the emission of chromium oxides from the steel. This chromium loss from the interconnect material destroys the fuel cell cathode.

Using the SAS grade of stainless steel solved the problem as its properties ensure chromium remains within the stainless steel interconnect material.

The current prototype size for the cell is 90 millimetres x 110 millimetres with the company anticipating using a variety of different shapes in the production stage.

Ceramic Fuel Cells Limited has schedules commercial production of the fuel cells to begin in late 2003.

This article featured in Australian Stainless magazine - Issue 17, January 2001.


Posted 1 May 2004

Choosing mainline fittings for irrigation applications can often seem like building a giant puzzle with elbows, tees, crosses and coupler sets - various fittings required to connect irrigation pipework together.

Pierce AustraliaHowever, Geoff Mellows from Yarrawonga Irrigation in Victoria may have solved the puzzle by using stainless steel mainline fittings - something that plastic fittings cannot yet match.

Poly, pvc and avs fittings are common materials in irrigation applications but because they are produced out of a mould, the combinations of size and outlet configuration are restricted.

Mellows said that by using stainless mainline fittings by ASSDA member, Pierce Australia, he can now “manipulate the angle, the shape, the variation and combination of outlets.“

The difference is simple. PVC and poly are bolted on, or welded and glued - making it difficult to change fittings”.

Stainless steel mainline fittings are the only rubber-ring jointed fittings available on the marketplace manufactured to the customers specific needs and can be fitted on any other combination because they are fabricated.

Stainless steel mainline fittings also provide flexibility of design in the angle of the fittings.

This also applies to the combination of outlets on those fittings and any other additional connections to that fitting.

With versatile stainless steel fittings, Mellows advice to customers is simple - “lay the pipe first and worry about the fittings later!”

This article featured in Australia Stainless Issue 28, May 2004.

Photos courtesy of Pierce Australia.


Posted 1 May 2004

Cleaner beaches and major water savings will be the chief benefits of the largest Sydney Water construction project ever undertaken on the New South Wales south coast.

ASSDA Member, Roladuct Spiral Tubing, supplied approximately 60 tonnes of grade 316 and 316L stainless steel tubing and associated fittings for the Wollongong Sewage Treatment Plant.The $197 million Illawarra Wastewater Strategy will see an overhaul of the 40-year-old Wollongong sewage treatment plant (STP) including the construction of a major new water recycling plant, high level (tertiary) treatment processes and ultraviolet disinfection systems.

ASSDA member, Roladuct Spiral Tubing, supplied approximately 60 tonnes of grade 316 and 316L stainless spiral tubing and associated fittings in 2mm to 5mm thicknesses for the project.

These materials were provided to Total Process Services for use throughout the Wollongong STP for the majority of the above-ground process lines.

An additional supply of 35 tonnes of grade 316 stainless tube and pipe fittings were provided by ASSDA Major Sponsor, Atlas Specialty Metals.

Sydney Water’s head contractor for the project is the Walter-Veolia Joint Venture. Walter Construction Group (Walter) is responsible for managing the delivery of the project and undertaking civil infrastructure construction at the treatment plants. Veolia Water Systems Australia (Veolia) is responsible for the process, mechanical and electrical design, supply, installation, commissioning and operational advice.

An additional supply of 35 tonnes of grade 316 stainless tube and pipe fittings were provided by ASSDA Major Sponsor, Atlas Specialty Metals The project’s most dramatic transformations are taking place at the Wollongong sewage treatment plant, where a 21 million litre bioreactor forms the centre-piece of the upgraded plant. Designed to remove organic impurities and nutrients from wastewater, the base of the bioreactor tank was poured over a continuous 15-hour period.

The design approach redirects wastewater from treatment plants at Bellambi and Port Kembla to the Wollongong facility. The Bellambi and Port Kembla plants will be converted to specialised storm-flow treatment facilities which will be used only in extreme wet weather.

The new Wollongong plant will also operate a reuse facility - supplying high quality treated wastewater to BlueScope Steel and cutting demand for fresh water from the local Avon Dam by about 20 percent. The upgraded sewage treatment plant is due for completion in mid 2005. The Illawarra Wastewater Strategy is part of WaterPlan 21, Sydney Water’s long-term strategy for sustainable water and wastewater management.

ASSDA provides technical advice and access to resources on the water and wastewater industries - for details phone 07 3220 0722.

ASSDA Major Sponsor, The Nickel Institute, can provide essential information on waste water. This information is available for download from www.stainlesswater.org.

Standards Australia distributes the Water Services Specification (WS-SPEC:2000) incorporating guidelines for stainless steel. Visit www.standards.com.au for purchase.

This article featured in Australian Stainless Issue 28, May 2004.

 


 

Posted 31 October 2005

Today, environmental factors are at the forefront of material selection for specifiers. Stainless steel’s long service life, 100 percent recyclability and its valuable raw materials make it an excellent environmental performer.

 

 

Stainless steel objects rarely become waste at the end of their useful life. Recycled stainless objects are systematically separated and recovered to go back into the production process through recycling.

As well as iron, stainless steel contains valuable raw materials like chromium and nickel which makes recycling stainless steel economically viable.

Stainless steel is actively recycled on a large scale around the world by recyclers who collect and process scrap (recycled stainless steel) for re-melting all around the world.

Scrap collection
The use of stainless steel scrap is fundamental to the steelmaking process. There are two types of scrap - reclaimed scrap (old scrap) and industrial scrap (new scrap).

Reclaimed scrap includes industrial equipment, tanks, washing machines and refrigerators that have reached the end of their service life.

Industrial scrap includes industrial returns or production offcuts from manufacturing by industrial engineering and fabrication sources.

Today, stainless steel is made up of approximately 60% recycled content including:

  • 25% reclaimed scrap
  • 35% industrial scrap
  • 40% new raw materials

The useful service life of stainless steel products is long so the availability of scrap is dependent on levels of production from decades ago.

With an average content of 25% of old scrap, stainless steel is close to the theoretical maximum content of material from end-of-life products.

Recycling the scrap
Specialised expertise and sophisticated technology is needed in recycling to separate and prepare each type of alloy for remelting.

A recycling processor feeds the scrap into a large shredder to break it into smaller pieces.

It is then chemically analysed and stored by type.

This process may include ‘blending’ the scrap into chrome steels, nickel alloys and other types of stainless steels.

After blending into piles for specific customer requirements the scrap is then loaded into containers for export to overseas mills.

The global market for scrap
Virtually, all Australian stainless steel scrap goes overseas. There’s a small market for stainless steel scrap in Australia for use in the foundries business. Foundries often use profile offcut or plate material scrap products.

At least 30,000 tonnes of stainless steel scrap in Australia will be exported a year to stainless steel mills in countries including China, South Korea, Taiwan, India and Japan.

China, for example, is using approximately 800,000 tonnes of industrial scrap. Reclaimed scrap is also on the increase in China and is expected to reach 2.5 million tonnes in 2005.

For mills, scrap is important because recycled stainless steel contains valuable raw elements including chromium, nickel and molybdenum that are gathered, processed and reused in the production process. The more scrap used in furnaces by mills, the less raw materials are required in the production process.

Stainless steel mills

Scrap along with other raw materials, ferrochromium (chrome/iron), ferro moly (molybdenum/iron) and nickel are blended into an electric furnace.

After melting, impurities are removed, the molten metal is refined and the chemistry analysed to determine what final adjustments are necessary for the specific type of stainless steel being produced.

The molten stainless steel is then cast into slabs or billets before production of plate, sheet, coil, wire and other forms in preparation for use by industrial manufacturers.

The stainless returns to you
Industrial manufacturers produce stainless steel items that you use everyday including cutlery, pots and pans, kitchen sinks and many architectural, industrial and other components.

At each stage of the production and use process, stainless steel retains its basic properties and utility value. Unlike many industrial and engineering materials, stainless steel may be returned to its original quality in the supply chain without any degradation.

You can be assured that even after its long service life, your environmentally-efficient stainless steel will always return to you bright, shining and new!

For more information about stainless steel, contact the Australian Stainless Steel Development Association on 07 3220 0722 or visit www.assda.asn.au

ASSDA acknowledges the assistance and contribution of Ignatius Brun of ELG Recycling Processors, the International Stainless Steel Forum (ISSF), the Nickel Institute and Peter Moore of Atlas Specialty Metals in the production of this article.

Consumption of stainless steel scrap - 2004

  • China — 2.8 million tonnes of production using 900,000 tonnes of scrap.
  • Japan — 2.4 million tonnes of production capacity using 900,000 tonnes of scrap.
  • South Korea — 2.3 million tonnes of production using  800,000 tonnes of scrap.
    Product mix 80% austenitic, 20% ferritic.
  • Taiwan — 2.6 million tonnes of production using 600,000 tonnes of scrap.
  • India  — 1.4 million tonnes of production using 300,000 tonnes of scrap.

Note: Australia sends a proportion of stainless steel scrap to all of the above countries.

This article featured in Australian Stainless magazine - Issue 33, Spring 2005.


Posted 31 January 2008

The thought of public rubbish bins usually attracts images of black smelly wheelie bins with broken lids and flies.  However, if you walked through the University of Queensland in Brisbane’s St Lucia, you would be greeted, instead, with clean stainless steel and lovely bright colours.

wheeliebins

The installation of between 30-50 new double-bin enclosures has added splashes of colour and flair to the university grounds.  Designers Street and Garden Furniture Co enlisted the services of long time contractors and ASSDA Accredited Fabricators Rocklea Pressed Metal to manufacture the pieces.

Featuring laser cut patterns, bright colour spray painting (to distinguish general rubbish from recycling) and a unique shape, the bins were designed with the surrounding art deco buildings in mind.

Street and Garden Furniture Co Director David Shaw says he often uses stainless steel for outdoor use because of its robustness and he found it particularly useful for the bins.

He says students tended to decorate large surface areas with posters, so using stainless steel meant they could be easily cleaned.

“Much of the damage is often caused by people emptying the bins,” Mr Shaw also says. “So we tried to design them to make them easily accessible.  If the surface gets damaged, they can be simply re-surfaced.”

Manufacture of the bins involved 12.24 square metres of 1.6mm grade 304 sheet with a number 4 finish and 18 lineal metres of 25 x 1.6mm grade 304 square tube. A considerable amount of laser cutting was done to adopt the academic shield and to break the large surface area with an aesthetic pattern.  A floating top was also designed to minimise the dominance of the wheelie bin size and to provide a shield against weather.

The designs were done by Street and Garden Furniture Co and then sent to Rocklea Pressed Metal as a CAD file.
David Shaw says his longstanding relationship with Rocklea Pressed Metal has been built through a history of confidence and delivery.

“An awful lot of the things we do, those guys are involved in,” he says.  “I am totally confident they’ll provide me with what I’ve drawn.”

The University of Queensland project is a longstanding one, dating back to 1997.  The project also incorporates the installation of light poles, tree grates, signage and seats, much of which Rocklea Pressed Metal has contributed to.

This article featured in Australian Stainless Issue 42.


Posted 1 October 2008

To overcome environmental concerns around landfill, Perth’s largest waste management authority, Mindarie Regional Council, is building a facility for the 70 per cent of household waste that is organic material and can be composted.

The $80m building is due for completion in 2009 and will save on landfill, reduce greenhouse gas emissions, and will produce a rich organic matter that may be added to Perth’s sandy soil.

The new composting facility, to be built using a prize-winning technology developed by Canadian firm, Conporec, comes at a time when the ongoing feasibility of landfill in crowded cities is questionable.

In September this year a new hazard came to light when residents of the outer-Melbourne suburb of Cranbourne were advised to leave after pockets of methane were found in their homes at a dangerous 60-65 per cent concentration. The methane had leached from a nearby landfill - concentrations of 5-15 per cent are considered an explosion risk.

The composting building’s odour removal system uses extraction ducts to capture and then transport air to a biofilter. Stainless steel was specified because of its corrosion resistance.

Organic waste is broken down as it would be in nature, but the composting process is much faster. The compost is produced in a sealed building at negative pressure, where moist air is forced through. The resulting atmosphere in the building is hot, humid and corrosive. Composting produces heat which quickens the corrosion process, particularly in Perth’s hot climate.

Turbo Air Technology Pty Ltd of Bayswater, Perth, fabricated the extraction ducts from AWM 404GP® stainless steel, supplied by ASSDA Major Sponsor Austral Wright Metals.
John Dubbelman, Managing Director of Turbo Air Technology Pty Ltd, says the best specification for the job wasn’t necessarily what had been used in the past.

“Experience with similar installations in Canada led the project managers Kerman Contracting Limited (KCL) to specify grade 304 stainless steel for the ducts,” John says.

“With the help of Austral Wright Metals, we were able to convince them of the fabrication and cost benefits of AWM 404GP®, a ferritic stainless steel with equivalent corrosion resistance to 304. We have used it for the lock-seamed spiral ducts, lobsterbacks, and plenums. We fabricated the new grade without dramas, and KCL is now installing it. It looks good.”

This article appeared in Australian Stainless Issue 44


Posted 31 January 2009

Australia’s first grain-to-ethanol refinery has begun production in Queensland, with an expected output of more than 80 million litres a year.

Seven pressure vessels and five columns were fabricated by ASSDA Accredited D&R Stainless from 30 tonnes of grade 304 stainless  steel supplied by ASSDA member Sandvik.

The column sizes range from an acid reduction column 750mm in diameter and 14.2 metres long to a beer column 1900mm in diameter and 24 metres long.

The columns were fabricated to tight tolerances set by process design engineers Detla T Technology, in the United States.

Chief Executive Officer of Dalby Bio-Refinery Limited, Kevin Endres, has worked with Delta T technnology in the US.

Mr Endres said stainless was the obvious choice for its durability. A project of this size requires a low maintenance and reliable material.

All design and manufacturing was carried out by D&R Stainless to ASME VIII complying with AS1210.

D&R also fabricated 6000 metres of grade 304 piping in sizes from 20NB to 500NB requiring over 6100 elbows, flanges and fittings from ASSDA member Stainless Pipe & Fittings Australia.

All piping was x-ray quality and met ASME B31.3.

Mr Endres said the refinery will eventually expand to output over 200 million litres of ethanol per year.

This article appeared in Australian Stainless Magazine -  Issue 45, Summer 2009.



Posted 1 December 2005

As many cities and towns across Australia continue to experience water restrictions due to the drought, seeking solutions to water saving is now a high priority with consumers.

Raincatcher - a unique design that separates the atmospheric and roof pollutants from the water.In 1994, ASSDA member, Hart to Hart Fabrications developed the Raincatcher - a unique design that separates the atmospheric and roof pollutants from the water.

The Raincatcher tank is manufactured from grade 304 stainless steel. Even parts like pins, hinges and filter screens are all made from stainless steel material.

Rainwater from the roof runs through the leaf diverter, removing leaves and large debris. The rainwater then flows through a unique filtration system, diverting atmospheric and roof pollutants away from the main water storage facility.

Raincatcher's main storage facility and filtration system is made from stainless steel due to its high resistance to corrosion, staining and bacteria.

The most frequent concern about drinking water is its bacteriological quality. Research has shown that there is about 100 times less bacteria residue on stainless steel than on other materials.

Raincatcher tanks are a useful solution to the health conscious water consumers, and also to people who live in areas which have particular problems with tap water.  It can be used in combination with existing rural water tanks.

Raincatcher can be used as an additional unit to an existing water tank. The water stored in Raincatcher has passed through the filtration system, making it excellent for drinking and kitchen use.

Raincatcher is an affordable alternative to tap water filtration units, and perhaps in the long term, to bottled spring and mineral water.

This article featured in Australian Stainless magazine - Issue 34 - Summer 2005.


Posted 31st January 2009



A weld-free installation process has caught the attention of Victoria’s caving community.

 

Parks Victoria and ASSDA member Stainless Tube Mills Fences Pty Ltd recently completed a visitor access upgrade for popular tourist sites, the Royal and Fairy Caves.

STM Fences’ patented assembly process for tubular panels allows for easy installation without the need for welding.

 

Ranger in charge of Buchan, Dale Calnin, said using this system meant installation wasn’t damaging to the caves’ sensitive environment.

“The stainless steel balustrading looked fantastic and is a well presented modular system,” he said.

Mr Calnin said this process would be welcomed by the international caving community.

220 metres of grade 316 stainless steel handrails and balustrading were installed to provide strong and durable protective barriers.

The application consisted of 50.8mm diameter top and bottom rails with 12.7mm diameter spigots, square mesh panels and fabricated stainless cable trays by Duraduct Pty Ltd.

Double top rails were also installed, using STM Fences’ innovative swivel cones to help with undulations throughout the caves.

A fine bright finish was applied by Stainless Tube Mills Pty Ltd and fabricated components pickled and passivated by Duraduct for maximum corrosion resistance.

Great caution was taken during installation to protect the caves’ delicate interior.

“STM Fences worked closely with Brettell Developments to ensure installation was handled appropriately for the environmentally sensitive area,” STM’s Peter Martin said.

This article featured in Australian Stainless magazine - Issue 45, Summer 2009.

Aussie icon immortalised in stainless

Posted 23rd September 2009

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A 200-year-old Australian icon has been immortalised in a new stainless steel home. The ‘Tree of Knowledge’ is cherished as the birthplace of Australia’s labour movement. It is believed that shearers gathered under the tree in 1891, striking for workers’ rights.

The $6 million timber and stainless steel memorial was officially unveiled earlier this year in Barcaldine, Queensland to house the remains of the tree following its death in 2006. ASSDA Accredited fabricator St Clair Sheetmetal supplied and installed 6.5 tonnes of mirror finished stainless steel cladding to achieve a highly reflective surface and provide a durable and stunning monument.

“We clad all the trusses of the mirror finish stainless steel so it looks like a cathedral inside,” David St Clair said. “The panels make the light reflect down underneath and takes away the brown of the building,” he said. The heritage-listed site is now protected from the elements and the Tree of Knowledge has been given a new lease on life.

P2181026

trythisone

This article featured in Australian Stainless magazine - Issue 46, Winter 2009.

new potential for mirror finish

Posted 23rd September 2009

HV2

A multi-award winning building design is using stainless steel to reduce its visual impact. ‘Zoo Booth’ is a small free-standing kiosk at Victoria’s Healesville Sanctuary and – thanks to its mirror finished stainless cladding – is very well camouflaged! The design concept came from Melbourne company TS1 Pty Ltd, who launched Transportable Design 1 (TS1) Pop-up Buildings in 2006.

For the unique application at Healesville, ASSDA member Stainless Sections provided grade 304, 1.2 mm stainless steel sheet, polished to a No. 8 mirror finish to reflect the organic surroundings. Stainless Sections’ Roy Carter said mirror finished stainless was the ideal material to achieve low visual impact in a natural setting whilst maintaining durability in an elemental location. TS1 is an expandable, relocatable space, completely construction-free and can be assembled in one day. It has become a popular solution to extending a living or work place, retail space or even for use as a spare bedroom.

TS1 Director Nadja Mott said her vision reflected a transient, nomadic lifestyle: her creations are transportable, low impact and fully recyclable. Mr Carter said the emerging market for reflective buildings has prompted further innovation to achieve solar reflection capture.

“This material allows concave shaping to be achieved which enhances marketing opportunities for mirror finished stainless in the growing green building market,” Mr Carter said.

HV2

HV1

LOUVER_02

This article featured in Australian Stainless magazine - Issue 46, Winter 2009.

stainless integral to design

Posted 17th December 2009

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A dam upgrade project in South Australia has achieved a world-first zero carbon footprint for water infrastructure and has used stainless steel as part of the unique design. The Little Para Dam upgrade incorporates a Hydroplus Fusegate System, with stainless steel fabrication carried out by ASSDA Accredited Fabricator LWA Engineering.

The Fusegates are similar to those built at Jindabyne for the Snowy Hydro in 2007, featuring a cast in-situ concrete design with stainless steel inlet wells and seal fixings in order to provide a 100 year design life and virtually no maintenance. However, for the Little Para dam upgrade, SA Water accepted the lean duplex stainless steel (LDX 2101) proposed by CivilTEC for the superstructure of the units for the following reasons:

  • it would provide similar corrosion resistance to 316 grade stainless steel, but with a higher tensile strength (450N/mm²) and at a much lower price;
  • an off-site fabrication system would reduce the amount of time required on site at Little Para from eight months to just six weeks, thereby reducing site administration overheads and running costs for all parties involved; and
  • the extremely efficient design (by WSP Group) used far less construction materials than would normally be required for a project of this nature and LDX 2101 is manufactured using approximately 65 per cent recycled material.

LWA Engineering Managing Director Larry Watson said LWA Engineering had been working with ASSDA Major Sponsor Sandvik on the stainless steel components of the project.

“With a Carbon Pollution Reduction Scheme on the agenda, a zero carbon footprint has never been more important,” Mr Watson said.

“One of the main reasons SA Water wanted to use this design with this material came down to the reduction in carbon footprint which minimised the offset required to achieve zero emissions. This is the first zero carbon infrastructure project in the country.”

The walls of the Fusegate bucket are formed from a composite steel shell comprising two 4mm thick stainless steel ‘skin’ plates spaced 150mm apart. A lattice work of ribbing is then welded onto the plates.

Around 70 tonnes of LDX 2101 were supplied by Sandvik for the walls and internal ribbing of the five Fusegates. The material was imported in 4mm thick coil form, which was then cut to length at Sandvik’s Sydney premises, with ribs being cut in Melbourne (RCR Laser) and Adelaide. The wall panels were cut on Sandvik’s 2m-4m laser bed to within ±0.2mm of accuracy.

LWA Engineering marked out the 2m high inner and outer ‘skins’ to form the composite wall panels and spot welded the vertical and horizontal 40mm-4mm thick LDX ribs in position before pre-setting and stitch welding. When the two ‘skins’ were brought together they were fixed in position using a 12mm diameter stainless steel rod which is pushed through 13mm holes in the overlapping lugs and welded at the top and bottom rib location.

Each Fusegate wall was fixed to a pre-cast concrete base chamber using a continuously welded stainless steel base plate cast into the concrete during pre-casting. Prefabricated inlet wells comprising 8mm thick LDX plate continuously welded along splice points were bolted into place on site.

The composite wall design saved about 40 per cent of the stainless steel required when compared with a traditional single-plate design.

The Little Para Dam spillway upgrade will be completed in early 2010.

CONTACTS

LWA Engineering
www.lwaengineering.com.au

Sandvik Australia
www.sandvik.com

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strength & corrosion resistance vital

Posted 21st April 2010

SeafoodInnovUnit

As wild fish stocks decline globally, the spotlight is increasingly being shone on humane stun and slaughter methods in the rapidly growing aquaculture industry. Stainless steel components fabricated by Pryde Fabrication (ASSDA Accredited) are an integral part of a Brisbane innovation that is leading the way internationally in a shift towards faster and more humane automated percussive stun methods.

Seafood Innovations International Group Pty Ltd has spent around 10 years developing fish harvest technology which enables fish to swim naturally until the second they are stunned, reducing stress on the fish and improving flesh quality.

They have collaborated extensively during this period with Pryde Fabrication (Cleveland, Queensland) to develop the system, which incorporates a base, ramp and trigger plate made from grade 316 stainless steel.

Up to 400 of the units are being produced each year, of which around 98 per cent are for export.

Pryde Fabrication General Manager Darren Newbegin said Grade 316 stainless steel was chosen for the components primarily due to its corrosion resistance and strength. He said other design and fabrication requirements included:

  • no bacterial traps
  • robust enough to withstand the harsh environment and repetitive shock loading
  • light enough to enable easy handling of the modules for cleaning
  • configured to enable easy dismantling for cleaning

“We never considered any grade other than 316 because of the harsh environment – the majority of the units are exported overseas, where they are being used in minus temperatures, fully immersed in sea water,” he said.

There is about 15kg of stainless steel in each machine, which is laser cut, enabling a high level of accuracy for both cutting and fold marks. The rest of the procedure is performed manually, including welding, polishing and glass bead blasting to provide a pleasing surface appearance.

“Stainless steel is the perfect material to laser because it’s so clean to cut,” Mr Newbegin said.

Seafood Innovations’ Business Manager Noel Carruthers said the development of the system had benefited from choosing a fabricator in the company’s local area, as it enabled a close collaboration.

Mr Newbegin agreed with this sentiment, suggesting it was this relationship between the two companies which had contributed to making the product fit for purpose and tailored to cost and operational efficiency.

“This relationship has allowed Pryde Fabrication to be involved in a solution to world fish farming and we are excited about further growth in this Australian initiative,” he said.

Mr Carruthers said the patented system represented an enormous change to the industry, with a single unit processing 15-20 fish per minute automatically, compared with other processes such as electrocution, carbon dioxide gas, and the use of wooden clubs.

The system works by pumping a current of water, which the fish are naturally inclined to swim towards. They then reach a point where their nose hits a trigger, which releases and immediately retracts a small, blunt-nosed piston at high speed, making the fish irreversibly unconscious. The fish are then turned upside down and enter a bleed machine where they are automatically bled.

In addition to improved flesh quality, the automated system means fewer operator injuries and immediate bleeding, resulting in improved appearance of fillets when fish are processed. The ability to slaughter at the point of capture means fish potentially carrying diseases will not contaminate other waters in transit.

Although originally developed for Atlantic salmon, the system has also been refined to cater for different varieties of fish, including tilapia, pangasius, barramundi, yellowtail kingfish and cobia.

A recent installation on a Marine Harvest vessel in Norway (incorporating three sets of a four channel system) is slaughtering 20,000 fish an hour at 98% efficiency.

The equipment has been independently tested by laboratories in Norway and ongoing developments to the system are tested at Huon Aquaculture in Tasmania.

CONTACT

Pryde Fabrication
www.prydefab.com

Polishing

Welding

Pryde close up

guidelines to ensure long service life

Posted 27th August 2010

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Design engineers frequently specify stainless steel in industrial piping systems and tanks for its excellent corrosion resistance. While stainless steel’s unique characteristics make it a standout leader in the durability stakes of alloys, it is not completely immune to corrosion.

Premature failures of the stainless steel can occur due to Microbiologically Influenced Corrosion (MIC). This corrosion phenomenon usually occurs when raw water used for hydrostatic pressure tests is not fully removed from the pipework and there is an extended period before commissioning of the equipment. The result is localised pitting corrosion attack from microbacterial deposits that, in severe cases, can cause failure within a few weeks. MIC is easily prevented using proper hydrostatic testing techniques.

MIC

MIC failures occur by pitting corrosion, often at welds, where colonies of bacteria may form. A number of different bacterial species are known to cause the problem, but the detailed mechanism is not known.

Iron utilising bacteria appear to be the dominating microbial species involved with MIC occurring in stainless steel. Anaerobic sulphate-reducing bacteria pose a greater risk of instigating or accelerating corrosion often under a layer of aerobic slime or microbial deposits. However others, such as manganese utilising bacteria (generally from underground waters), have also been discovered.

MIC is extremely aggressive and difficult to eliminate once established, so it is surprising and disappointing that there is limited knowledge of MIC within the engineering community. Fortunately, MIC is easily avoided by using good practices during the initial hydrostatic testing. Education and promotion of proven hydrostatic testing practices which prevent MIC are vital to minimising its potential impact on the stainless steel industry.

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Hydrostatic testing practices to eliminate MIC

In order to eliminate MIC, it is recommended that the following practices are used.

1. Fabrication practices

Crevices should be eliminated or at least minimised during the fabrication process, as they are the preferred sites for attachment and growth of microbial colonies. They also provide traps for chemicals which could concentrate and cause pits.

The likelihood of MIC will also be reduced by:
> using full penetration welds; and
> purge welding to prevent the formation of heat tint; or
> removing heat tint by grinding or pickling.

Arc strikes and weld splatter should also be ground off and pickled.

2. Use clean water

The cleanest water available should be used in a hydrostatic test, such as demineralised, steam condensate or treated potable water. Untreated or raw water from dams or bores should be avoided when conducting a hydrostatic test but, where this is not possible, the water should be sterilised (eg by chlorination) before use. If sterilisation is not practical, the requirements for short residence time and subsequent drying of the system are extremely important. The cleaner the water, the less ‘food’ there is for MIC bacteria to live off and multiply.

It is important to ensure that there is no trace of sediment in the stainless steel system during testing to avoid silting, as the water is normally not circulated during a hydrostatic test. This may require the test water to be filtered to ensure it is free of all undissolved solids. Sediments can provide the conditions for crevice attack.

3. Draining and drying

Thoroughly draining and drying the stainless steel system immediately following a hydrostatic test (preferably within 24 hours, certainly within 5 days) will almost certainly prevent the occurrence of MIC.

Horizontal pipelines should be installed in a sloping direction to make them self-draining.

Drying can be achieved by pigging (cleaning with foam or rubber scrapers), followed by blowing dry air through the system. Beware of blowing higher temperature moist air through cold pipework unless the air is dried before being introduced to the system. If warm air is used, it should not be from a gas burner as condensation may occur.

Draining and drying of systems following a hydrostatic test should only be disregarded when the system is placed into service immediately following the test. Partial draining is potentially very serious as subsequent slow evaporation of even clean residual water can produce very concentrated and aggressive solutions.

Figure-1

4. Chloride content and temperature

During hydrostatic testing of stainless steel equipment, the chloride content of the test water must be within the range to which the stainless steel grade is resistant. Figure 1 shows the maximum temperatures and chloride contents to which stainless steels are resistant in water with residual chlorine of about 1 ppm.

The limits shown in Figure 1 may be exceeded provided the contact time of the water is brief, ie 24-48 hours.

If the chloride content of the test water is uncertain, the water should be analysed.

5. Standards

NACE and API standards for a number of products and installations provide guidelines for hydrostatic testing, including limits for water quality and contact times. These standards should be consulted for specific details for the fabrication in hand.

Conclusion

The benefits of stainless steel’s corrosion resistance are well proven in many industrial applications involving piping systems, but failures can occur during hydrostatic testing if care is not taken. Attention to a few simple details will prevent surprises a few months down the track, allowing the long service life available from stainless steel to be fully realised.

stainless technology essential

Posted 27th August 2010

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Guaranteeing water supply in Australia is thirsty work. Western Australia’s new Southern Seawater Desalination Plant, currently under construction north of Bunbury, will help quench Perth residents and businesses with up to 100 billion litres of water a year. In such a highly-corrosive salt water environment stainless steel is a natural fit.

Sea water is pumped from the ocean and its high salinity is extremely corrosive. The desalination plant uses reverse osmosis to purify the sea water, essentially pushing it through a fine membrane at high pressure.

The first pass (first membrane) is the most corrosive environment which is why super duplex stainless steel is essential. Following passes, which have much lower levels of salt and are almost fresh water, require duplex and grade 316 stainless steels.

A collaborative effort of WA stainless steel expertise ensured the best knowledge was applied to the 200-plus tonnes of piping in the plant.

Alltype Engineering was contracted to supply the complete reverse osmosis racks (see image above) with super duplex, duplex and 316 stainless steels required for all the connecting pipe spooling. Project Manager Keith Thomas-Wurth said the the energy recovery devices and the pipe spooling connecting the reverse osmosis racks with the pressure pumps were subcontracted to ASSDA Accredited Fabricator Weldtronics Australia.

International Corrosion Services’ pickling and passivation treatments were central to ensuring the performance of the stainless steel entering the plant. They use Avesta Finishing Chemicals supplied by Bohler Welding Australia (a division of Bohler Uddeholm Australia).

408---lightened72dpiRGBICS Business Development Manager Stuart Norton said the opportunity to apply the pickling and passivation processes to 200 tonnes of piping came at the right time.

“We’ve just developed the largest nitric and hydrofluoric acid tanks in the southern hemisphere, and they’ve been used to treat the stainless steel to ASTM380-06,” he said.

The near 20m3 tank is a realisation that the industry will move towards longer pieces, particularly in piping, saving on fabrication time and reducing the number of joins – ultimately providing less opportunity for corrosion.

Southern Seawater Joint Venture Mechanical Engineer Juan Jose Perez said that the stainless steel piping in particular is one of the most important elements of the desalination plant’s construction.

“The membrane is the core of the plant and, in turn, the core of the filtration process. The salt water is passing through the stainless steel pipes to get to the membrane and any corrosion, any tiny particle, can damage the membrane which is extremely expensive,” Mr Perez said.

“Suppliers of the membranes run regular checks to detect for corrosion and, if they detect it, it could potentially affect functionality, even warranty of the membrane. So we rely on the stainless steel, particularly inside the pipes, to be of the highest quality. This is why the pickling and passivation process is so important.”

Mr Norton said that ICS heard the industry screaming out for larger tanks for pickling and passivation jobs such as the one undertaken for Southern Seawater and undertook the two-year journey to get the required authorisation.

“Obviously there are some key environmental and waste treatment factors involved in this. Our waste-water process was made easier by constructing an in-house acid neutralisation tank plus a filter press to push heavy metals out of the acid before sending it off to be further treated,” he said.

The trend towards desalination as a water supply method is clear: when Southern Seawater comes online in late 2011 desalinated water will account for 30 per cent (up from 16 per cent) of WA’s total water supply.

This trend means that further use of large-scale pickling and passivation is likely as stainless steel continues to prove to be an essential and trustworthy component of the desalination plant’s construction.

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This article featured in Australian Stainless magazine - Issue 47, Spring 2010.