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Stainless Provides Strength and Style

Taking pride of place within Perth’s Optus Stadium Park is the Arbour featuring a stainless steel cable net canopy delivered by ASSDA Member Structural Dynamics.

The 60,000-capacity arena is the latest major development to hit Western Australia’s capital, boasting a world-class multi-purpose venue that combines innovative design with community infrastructure.

The impressive Arbour stands 10m tall and 20m wide, and stretches 450m around the south side of the Stadium. It connects a new six-platform railway station to the Swan River, over which the Matagarup Bridge is currently being constructed to provide pedestrian access to East Perth.

Over a thousand stainless steel cables were installed on the 43 arches that make up the Arbour to create a tensile structure in the form of a canopy. Suspended on the structure using bespoke fittings are 3,076 bronzed artwork panels reflecting Whadjuk and Noongar stories. 

Stadium Park was constructed on wetlands with cultural heritage significance to the Indigenous community, and its rich Aboriginal history was the inspiration behind the Arbour’s design.

More than 13 tonnes of grade 316 stainless steel was used, including in excess of 14km of 16mm and 8mm hammaTM X 1x19 wire rope supplied by ASSDA Member Arcus Wire Group, 20,000 bespoke fittings and over 34,000 screws.

Stainless steel was specified for the cable net canopy for its strength and durability to withstand the harsh Western Australian weather conditions, including powerful coastal winds driven from the Indian Ocean. The 16mm edge cables on the structure were tensioned to forces up to 52kN, with the 8mm longitudinal and transversal cables tensioned up to maximum of 11kN.

In addition, the high quality and aesthetical value of stainless steel complemented the Arbour’s design in creating an eye-catching structure for patrons.

Structural Dynamics provided value engineering and practical advice to the project engineer Maffeis Engineering and project architect Hassell on how to best integrate stainless steel tensile systems into the design.

Their in-house team of engineers used structural and finite element analysis as components of the detailed analysis and modelling on how the cable design would behave and interact within a tensile architecture installation.

Structural Dynamics also worked with engineering firm Partridge to undertake the final design, review, slip testing of the bespoke cable clamps and final sign off for the project. Each of the eight different types of cable edge clamps were sent to the National Association of Testing Authorities’ (NATA) accredited laboratory for slip testing under wet and dry conditions to ensure their strength and adequacy.

The cable fittings were designed to the AS 1170 series: Structural Design Action, AS 4100: Steel Structures and AS 2759: Steel Wire Rope – Use, Operation and Maintenance.

Structural Dynamics’ Project Manager Shaun Salmon explained the logistics of the assembly of the Arbour whilst maintaining safe and continued access to the Stadium for more than 1,000 workers. ‘It was important during the installation process that our team of skilled and qualified tradesmen and riggers followed the approved construction sequencing and quality management system processes whilst not impeding access to the Stadium from the primary entry point on the southern concourse. Both temporary and permanent bracing measures were used throughout construction along with sequential tightening and regular cable tension testing to achieve the design intent drape and sag of the cable net canopy and not applying adverse force to any single point on the structure.’

Structural Dynamics’ collaboration with the multiple stakeholders involved in the Arbour design and construction ensured the successful delivery of a custom-designed stainless steel cable net canopy providing the flexibility, tensile strength and structural performance required.  

Optus Stadium officially opened on 21 January 2018 and is the new home game venue of local Australian Football League teams Fremantle Football Club and the West Coast Eagles.

 

        

 

Arbour photos courtesy of Structural Dynamics. Photography by Abigail Harman.

Aerial photo of Optus Stadium Park courtesy of MakMax.

This article is featured in Australian Stainless Magazine #61.

Stainless Sustains Intricate Brick Facade

Stainless steel is playing a vital role in the structural integrity of a new state-of-the-art library at one of Brisbane’s most prestigious boys’ school.

The Centenary Library at Anglican Church Grammar School was designed by Brand + Slater Architects, and the ambitious project was part of the school’s master plan to provide a technology-rich, world-class centre for its 1800 students. Comprising four levels, the tertiary-inspired building features an extensive range of learning spaces including a 250-seat lecture theatre, teaching and meeting rooms and over 80 individual study areas.

The library stands 23.5m tall on a heritage-listed part of the school campus. Paying homage to the school’s history whilst appealing to a contemporary aesthetic, the library exterior features an intricate brick façade backed by a stainless steel support and restraint system custom-designed and manufactured by ASSDA Member and Accredited Fabricator, Ancon.

Grade 304 stainless steel was used and specified for its longevity, durability and performance properties to meet the building’s 50+ year design life.

Ancon’s specialist knowledge, manufacturing agility and project management service proved invaluable to the contractor when building the detailed façade of the decorative arches and corbelled brickwork with all structural steelwork now unseen.

Shelf Angle Brick Support

Ancon masonry support systems enabled the large-scale brick cladding installation on this impressive education facility to be completed to the highest safety standards, while showcasing its architectural brickwork features.

Ancon’s MDC and CFA continuous shelf angle support systems carry the intricate brick façade, consisting of freestanding archways and projected brickwork. The MDC stainless steel angles are fixed to the reinforced concrete frame, span a 40mm cavity, and create a horizontal shelf to provide the necessary support for up to 3 metres of brickwork.

Cast-In Channel

Ancon’s 30/20 cast-in horizontal channels were used to provide the fixing between the concrete frame and shelf angles. The channel enabled the necessary horizontal adjustment for the installer, and its compact size eliminated the issue of potential clashes with the reinforcement steel in floor slabs.

Nail holes aided the fixing of channels to timber framework and an infill prevented the ingress of concrete during casting. Cast-in fixings do not generate expansive forces in concrete. It can therefore be used at close centres and often used closer to the edges than expansion fittings.

Wall Ties and Restraint Fixings

To restrain the distinctive brickwork details to the reinforced concrete structure, stainless steel L-shaped SPB and SDB frame cramps were fixed into the reinforced concrete using 6mm FBN expansion bolts.

FBN single expansion bolts are a cost-effective anchor and fix into a hole similar to the diameter of the bolt. This allows the hole to be drilled through the hole in the item to be fixed.

Technical Expertise

As part of Ancon’s free design service, plans were produced illustrating the location and reference of all fixings required. Ancon’s early engagement with the project’s structural engineers, Bligh Tanner, enabled a workable and cost-effective design to be agreed upon prior to the build of the complex masonry features. Sharing their expertise with the clients at this stage of the project meant installation difficulties, site delays and unnecessary remedial measures were avoided.

  

 

Centenary Library photo (above); Copyright: Christopher Frederick Jones.

This article is featured in Australian Stainless Magazine #61.

The Family of Duplex Stainless Steels

The use of duplex stainless steels has grown globally based on their strength, corrosion resistance and a range of properties that improve equipment life.

The name duplex is sometimes used to describe Alloy 2205 (UNS S31803 or UNS S32205), however duplex is a family of alloys ranging from lean duplex and standard duplex to super duplex stainless steel.

HISTORY

Duplex stainless steel was first developed in France and Sweden in the 1930’s, with the early grades becoming a forerunner for AISI 329, but a lack of control over the chemistry and lack of adequate welding products and techniques impeded development of the product.

Cast versions eventually became available and were subsequently used successfully in many industries where some corrosion, wear and strength were required.  

Areas such as pump components saw a raft of duplex grades developed in standard and super duplex. It should be noted that further work or welding was not required with these particular forms.

In the 1970’s Swedish manufacturers produced and marketed what could be described as a lean duplex called 3RE60 (UNS S31500) with lower chromium, nickel and nitrogen than grade 2205.

3RE60 had success with tubing and displayed excellent resistance in replacing 304 and 316 tubes that had previously failed due to chloride-induced stress corrosion cracking.  The use of 3RE60 in vessels was less successful due to issues such as inter-granular corrosion (IGC) from early welding techniques. The issue was not with the grade but with fabrication, as well as the melting technique to enable control of alloying elements to provide a consistent structure and provide predictable strength and corrosion control.

In the late 1970’s grade 2205 arrived in the market, initially as a tube, then in flat-rolled and other products. The point-of-difference from earlier attempts was well-documented welding technique control, which lead to the increased usage of duplex.

The grades displayed higher strength than standard austenitic grades, excellent resistance to stress corrosion cracking and improved pitting resistance. The other driver was the rising price of nickel, which added a commercial advantage over using a lower nickel duplex product.

GRADES OF DUPLEX

The grades are listed in three groups; standard, lean and super.

The major difference between each grade is corrosion resistance.  This is based on a Pitting Equivalent Number: 

(PREN) = %Cr + 3.3 x %Mo + 16 x %N.

This is a comparative rating that relates to the critical pitting and crevice corrosion temperatures in hi chloride environments (CPT and CCT respectively).

DUPLEX TYPE PREN
Standard Approximately 35
Lean 25-30
Duplex Above 40

USES OF DUPLEX STAINLESS STEELS

Stress corrosion cracking (SCC) is a form of corrosion that occurs with a particular combination of factors:

  • Tensile stress;
  • Corrosive environment; 
  • Sufficiently high temperatures: Normally above 60°C but can occur at lower temperatures (around 30°C in specific environments, notably unwashed atmospheric exposures above indoor chlorinated swimming pools). 

Unfortunately, the standard austenitic steels like 304 (1.4301) and 316 (1.4401) are the most susceptible to SCC. The following materials are much less prone to SCC:

  • Ferritic stainless steels;
  • Duplex stainless steels;
  • High nickel austenitic stainless steels;

 The resistence to SCC makes duplex stainless steels suitable for many processes operating at higher temperatures. Examples of the successful use of duplex stainless steel are hot water tanks, brewing tanks and thermal desalination vessels.

WHERE CARE IS REQUIRED WITH DUPLEX STAINLESS STEELS

Duplex stainless steels can also form a number of unwanted phases if steel is not given the correct processing, notably in heat treatment. Phases like sigma phase leads to embrittlement, meaning the loss of impact toughness, but sigma phase also reduces corrosion resistance.

The formation of sigma phase is most likely to occur when the cooling rate during manufacture or welding is not fast enough. The more highly alloyed the steel, the higher the probability of sigma phase formation. Therefore, super duplex stainless steels are most prone to this problem. Another form of embrittlement occurs above 475°C, and it can still form at temperatures as low as 300°C. This leads to the design limitations on the maximum service temperature for duplex stainless steels.

SUMMARY: DUPLEX CHARACTERISTICS

Compared to the austenitic and ferritic stainless steels, duplex can give:

  • Up to double the design strength;
  • Good corrosion resistance depending on the level required;
  • Good toughness down to -50°C;
  • Excellent resistance to stress corrosion cracking;
  • Welding in thin and thick sections with care;
  • Additional effort required due to high mechanical strength;
  • Up to 300°C maximum in service.

  

Author: Trent Mackenzie is a metallurgist with more than 35 years experience in the industry and General Manager of ASSDA.

Photos courtesy of Outokumpu.

This article is featured in Australian Stainless Magazine Issue 60 (Summer 2017/18).

Stainless Steel Shines in Perth's Elizabeth Quay

The successful collaboration of ASSDA members and their expertise in the extensive use of stainless steel has been integral to bringing Perth’s iconic and most complex bridge to life.

The Elizabeth Quay Pedestrian Bridge was constructed by DASSH, a joint venture between Decmil, Structural Systems and Hawkins Civil, and is a key feature of the Elizabeth Quay mixed-use development project core to revitalising Perth’s CBD.

Designed and engineered by Arup, the cable-stayed suspension bridge features a leaning double arch, is 22m high, 5m wide and is suspended over the inlet of the Swan River with a clearance of 5.2m from the water. The 110m long meandering pedestrian and cyclist bridge allows for continuous movement around the Quay, connecting the new promenades, an island and ferry terminal.

Stainless steel reinforcement plays a vital structural role in the bridge, with ASSDA Sponsor Valbruna Australia supplying approximately 89 tonnes of 2304 grade Reval® in 12, 20, 25 and 32mm reinforcement bar for the three concrete river piers. The reinforcement bar diameters originally specified were not available locally and so the design was modified to accommodate what was ex-stock in Australia to minimise construction downtime.

Installed exclusively in the splash zones of the concrete piers, stainless steel reinforcement was specified to resist corrosion attack and prevent concrete spalling. In addition, the overall mass of the concrete piers had to be minimised in order to support and achieve the sleek, sinuous design of the almost 200 tonne arches.

Reduction in concrete mass decreases the overall protection of the installed reinforcement bar, resulting in stainless steel as the material of choice to achieve the slimmer river piers and meet the demands of the architectural design.

During the grade selection process, grade 2304 lean duplex stainless steel was also deemed the most cost effective option to reduce ongoing maintenance costs and deliver the expected 100-year service life of the structure.

Visually, stainless steel is also featured in the key design elements of the bridge, including the handrails, balustrades, support posts, mesh barriers, kerbing, fascia panels and kick rail stations. Local jarrah timber decking and decorative feature lighting was used to complete the durable and low-maintenance walk and cycle way.

ASSDA Member Stirlings Australia supplied over 60 tonnes of stainless steel for the bridge project, including 111 wire mesh panels, over 300m of 50.8mm x 3mm round tube in a 320 grit finish to support the mesh panels, welded pipe for the handrails and balustrades, and 2205 and 316/316L grade plate in 6mm and 10mm. An additional 52 tonnes of 316/316L and 8 tonnes of 2205 grade stainless steel plate was supplied and laser cut in-house by Stirlings Australia using their 6000mm x 2000mm laser cutting machine for large-format materials.

Furthermore, Stirlings Australia supplied 7 tonnes of stainless steel channel and angle bar for the architectural elements and structural sections of the quay’s new ferry terminal.

ASSDA Sponsor Vulcan Stainless also supplied the project with over 50 tonnes of laser cut 2205, 316 and 316L grade stainless steel. Polished 2205 grade 3mm stainless steel plate was supplied via its Sydney service centre, cutting approximately 10 tonnes of coil to length, which was then laser cut to size and polished to the specified No. 4 finish prior to delivery. Upright and support pieces for the balustrading were also laser cut and supplied from Vulcan Stainless’ Sydney and Perth service centres using 316 grade 12mm and 316L grade 16mm stainless steel plate.

The 25mm thick pieces were cut using Vulcan Stainless’ in-house 8kw Trumpf Laser, the only machine in Western Australia able to laser cut at this thickness including holes.

Both Stirlings Australia and Vulcan Stainless also supplied laser cut 316/316L grade stainless steel plate for the planter beds that formed part of the landscaping around the Elizabeth Quay precinct.

ASSDA Member Unifab Welding was contracted to fabricate and install over 60 tonnes of stainless steel for the visual elements of the pedestrian bridge as supplied by Stirlings Australia and Vulcan Stainless.

Over 60 different individual balustrade sections each at 1800mm tall were fabricated to allow for the shape and movement of the bridge. Manufactured in compliance with AS/NZS 3992 and ASME 9, Unifab Welding used gas manual arc welding (GMAW) and gas tungsten arc welding (GTAW) techniques to fabricate the various sections.

To meet strict deadlines, all kerbing pieces were welded together using 8mm stainless steel flat bar to replicate the originally specified 300x100x8mm rectangular hollow sections (RHS), a product that was not locally available off-the-shelf. The kerbing pieces were also polished back to a 320 grit and No. 4 finish.

Aside from the wire mesh, all stainless steel components for the bridge were polished to Ra<0.5 and then electropolished prior to installation to provide maximum corrosion resistance in the salt-water environment.

A key architectural feature of Elizabeth Quay, the pedestrian footbridge was opened to the public in January 2016. It exudes in quality, aesthetic appeal and durability with its extensive use of stainless steel, and is certain to provide the structural and material performance required to stand the test of time.

Offering 360-degree views, the bridge is an exciting addition to Perth’s CBD and provides increased opportunity for locals and tourists to interact with the Swan River and reinvigorated waterfront destination.

This article in Australian Stainless Magazine Issue 58 (Summer 2016/17).

Running Water

Water authorities tackle water shortages with stainless steel.

Water is a fundamental human need. It is central to our lives, from what we drink, to what we use in washing ourselves, our clothes and a multitude of other uses. Safe, clean and palatable water comes at a price though, and when leaks occur in distribution systems, additional costs are incurred as even more water must be found and treated. Security of water supply is a prerequisite for sustainable growth and dealing with leakage is a universal challenge. To combat the scourge of leaks, a number of water distribution authorities across the world have implemented affordable solutions utilising stainless steel, which not only saves money, but water, a precious resource.

Tokyo, Japan

Prior to the 1980’s, water shortages in Tokyo were chronic and rationing was occasionally required. When the city’s water provider, the Tokyo Metropolitan Government Waterworks Bureau (TMGWB), analysed leakage repairs, they determined that 97% were on the distribution pipes of 50mm diameter or less. In Tokyo, there are more than two million such connections that take the water from the mains to internal systems in buildings. Historically, lead pipe was the preferred material for distribution lines because it is soft, malleable and easy to work with, especially for the last few metres from the mains to buildings. Once lead pipe is in the ground, however, various forces can act on it. Vibrations from traffic and construction work as well as subsidence and earthquakes can cause the soft lead pipes to deform, become detached or even break.

In 1980, TMGWB started to actively replace all service connections with grade 316 (UNS S31600) stainless steel pipe. In 1998 corrugated grade 316 (S31600) stainless steel pipe was introduced for distribution lines that take water from the mains to final destinations in homes, offices and industrial plants. The pipe is corrugated at regular intervals to allow for it to be bent during installation, to accommodate changes in direction and the avoidance of obstacles without additional joints. It also allows for movement of the pipe during earth movement and seismic events. By supplying a single length of corrugated stainless steel pipe, the number of pipe joints was greatly reduced. In switching to stainless steel pipe, the reliability of the water supply has increased and the leakage rate has been reduced by 86% from 15.4% (1980) to 2.2% (2013). To put this into context, since 1994 Tokyo has reduced annual water leakage by nearly 142 million cubic metres - the equivalent of 155 Olympic-size swimming pools per day, with savings in excess of US$200 million per year. Also, annual leak repairs have decreased from 60,000 (1983) to 10,000 (2013). Due to the corrosion resistance of stainless steel, TMGWB expects service life in excess of 100 years.

Graph below: Correlation between repair cases, leakage rates and installation of stainless steel pipes in Tokyo.
Courtesy of the Bureau of Water Works, Tokyo Metropolitan Government.

 

Taipei, Taiwan

In 2002, a severe drought brought intermittent water supplies to the Taiwanese capital over a 49-day period. Of the 450 metering areas in the city, 40% were losing half of their water or more before it reached consumers.

Analysis of repair cases showed that while polybutylene pipe made up only 3% of the length of the system, it accounted for 28% of all leaks. Approximately 90% of all problems occurred in plastic pipes, with the vast majority (83%) caused by cracking.

In 2003, the Taipei Water Department began a similar program to Tokyo, replacing distribution lines with corrugated grade 316L (S31603) stainless steel pipe. Although the ongoing program has so far only replaced 35% of the lines, the result has been a reduction in water loss from 27% (2003) to 17% (2014). This adds up to an annual saving of 146 million cubic metres of water, the equivalent of 160 Olympic-size swimming pools per day.

In 2014, a drought occurred with even less rainfall than the 2002 event which precipitated the pipe replacement program. However this time, the improvement in leakage rates achieved since 2003 meant there was no interruption to the water supply.

The 2002 drought in Taipei caused severe water shortages.
Image courtesy of the Taipei Water Department.

 

Western Cape, South Africa

South Africa is by nature a semi-arid country; its annual rainfall is only half the global average. It has a population of 55 million and is facing freshwater scarcity. It is estimated that at least 37% of its clean drinkable water is lost due to leakage from old and unreliable infrastructure.

The Groot Drakenstein Valley is the cradle of the South African deciduous fruit and wine industries. Water is supplied to over 800 farms including 50 vineyards. Here, there are numerous examples of carbon steel and cast iron pipes that have failed in many areas after just one year due to the very aggressive acidic soils and high water table. “We started a project in 1992 in the Drakenstein Municipality to replace existing piping with stainless steel,” explains André Kowalewski, Senior Engineer - Water Services, Drakenstein Municipality. “We have reduced water loss to around 13% in comparison to the 37% national average. Ten years back only the Drakenstein Municipality used stainless steel. Now 80% of the Western Cape municipalities do.”

André and his team plan for a life expectancy in excess of 50 years. Stainless steel used in Drakenstein is primarily grade 316 and in some cases grade 304 (S30400) in visible locations. Projects are currently focussed around pumping, purification, storage, pipelines and sewage. One such project is a 500 mega-litre/day delivery system completely in grade 316 stainless steel.

Stainless steel pipe in the Western Cape resists aggressive acidic soil conditions.
Images courtesy of Johan Van Zyl.

   

 

Investing in the future

The experience of Tokyo, Taipei and the Western Cape gives water authorities the confidence to specify stainless steel for piping systems. While the initial cost compared to competing materials may be higher, stainless steel has been shown to be a good investment over its long life, paying back each year in reduced maintenance and cost per litre processed.

This article was originally printed in Nickel Magazine (August 2016, Vol. 31, No.2), published by ASSDA Sponsor Nickel Institute.

This article is featured in Australian Stainless Issue 57 (Spring 2016).

Banner image: Corrugated pipe installation. Image courtesy of Tokyo Suido Services/Showarasekan.

Stainless Steel Design Innovation

Brisbane’s iconic Story Bridge is sporting increased safety measures with the application of innovative stainless steel products and laser-fusion technology.

 The 76-year old heritage-listed cantilever bridge now incorporates three-metre tall, stainless steel safety barriers on its pedestrian walkways, as a result of an outstanding collaboration between multiple project stakeholders. Completed in December 2015, the $8.4 million project was led by design and construct head contractor, Freyssinet.

The design brief was to develop an anti-climb structure that was both functional and aesthetically appealing, whilst ensuring the heritage values of the bridge were maintained.

This presented a number of engineering challenges, including the affixation of the barrier structure to the existing heritage-listed bridge without permanent methods of attachment, such as welding or other damaging techniques, whilst addressing the weight and wind load tolerances, ambient vibrations and noise potential.

Visually, there was also a key design requirement to ensure pedestrian views of the river, Brisbane city and surrounds, and of the Story Bridge itself, was preserved.

The initial reference design was specified in stainless steel (with an option for painted carbon steel) and required the fabrication of heavy box sections for over 1000 posts to support a tamper-resistant, horizontal balustrade cable system. The outrigging was specified in carbon steel, with isolation joints to support the upright posts. However, aesthetically, this design created a clutter of vertical elements.

Freyssinet developed an alternative design concept employing Carl Stahl X-TEND® stainless steel mesh, and engaged ASSDA Member Ronstan Tensile Architecture to assist in the design rationalisation. Ronstan Tensile Architecture conducted form-finding analysis to mimic increasing the mesh self-span between the posts. The findings resulted in a substantial reduction in the number of posts required and a more secure fall-restraint system than initially designed.

Replacing the original tension wire design with a mesh barrier significantly reduced the structural loading on the posts, allowing for a smaller number of lighter duty posts, and reducing the cost below the initial estimate.

The concept solution delivered was a dynamic structural design that met the exacting demands of the specification. The design evolved to using laser-fused stainless steel open section beams for the posts, positioned approximately three metres apart with a blackened Carl Stahl X-TEND® stainless steel mesh barrier.

This project is the largest to date in Australia using laser-fused stainless steel structural beams.

Low impact laser-fusion is a process that allows the welding together of pre-polished flat components to a special profile without damaging the visible surface. It provides an effective and economical alternative to extrusions or conventional welds, providing closer tolerances, superior joint integrity and more consistent finishes.

The introduction of laser-fused stainless steel structural beams into the Australian market allowed Freyssinet the flexibility to plan and design with stainless steel in an outcome that was unrivalled for the project scope. Developed and manufactured by Montanstahl (Switzerland) and its subsidiary Stainless Structurals Asia (Singapore), the laser-fused stainless steel structural beams were supplied by ASSDA Sponsor Atlas Steels, as the exclusive agent for the product in Australia.

To this end, Atlas Steels supplied over 30 tonnes of stainless steel for the project, including 316L grade 80x80x6mm I-beam sections for the 530 upright posts, 316 grade 65x65x6mm angle bars for the outrigging, and 316 grade 38.1x1.6mm 320 grit polished tube for the framing of the mesh.
The I-beams supplied were made from a pre-polished strip with a <0.5Ra finish. The I-beam components were laser cut, polished, and then laser-fused together.

Freyssinet rolled the I-beams using a local roll forming company in Eagle Farm to form a curve, following several prototypes to achieve the required design. The beams were then delivered to ASSDA Accredited Fabricator Stainless Engineering Services to cut the posts to the specified height, verify the dimensions, placement and drilling of the holes for the bolt connections, and passivate the posts to ASTM 380 prior to installation.

Stainless Engineering Services also used the offcuts from the I-beams to fabricate the brackets, ensuring no material wastage.

ASSDA Member Anzor Fasteners supplied 550 units of grade 316 stainless steel coupling cables in various lengths of up to 2.1 metres, in 4mm diameter and 1/19 configuration. Each cable was swaged to a threaded stud on one end and a u-shaped fork coupling on the other end. The coupling cables were used to affix the X-TEND mesh to the posts, providing an adjustable method of attachment.

Following the erection of the posts, Ronstan Tensile Architecture supplied and installed 3400m2 of Carl Stahl X-TEND® 316 grade stainless steel mesh constructed from coloured stainless steel wire rope. The stainless steel was blackened with an additional polyester amino resin, which was hardened to the wire under temperature.

The blackened Carl Stahl X-TEND® mesh was the key to achieving an unobtrusive composition and historical aesthetic, while providing the flexibility and tensile strength required for the structure’s design and use of the laser-fused posts.

The structure is a pivotal safety addition to the Story Bridge and exudes functionality in its excellent and unique engineered design. Stainless steel is unmatched in the materials selection for providing durability, structural performance, low maintenance, corrosion resistance and aesthetics.

This article is featured in Australian Stainless Issue 56 (Winter 2016).

Photography by Fullframe Photographics.

A Walk to Remember

The spirit of the Anzacs is evoked in a new architecturally stunning, stainless steel walkway that unfolds around Newcastle’s cliffs and links Strzelecki Lookout to Bar Beach.

 The much-anticipated Newcastle Memorial Walk opened on 24 April 2015 on the eve of the Anzac centenary, and features spectacular 360-degree views of Newcastle city and coastline.

The 450m raised walkway forms part of Newcastle City Council’s ‘Bathers Way Project’, a $29 million foreshore development and revitalisation program to link Merewether Beach with Nobby Beach via a coastal walk. The total cost of the walkway was $4.5 million, $3 million of which was contributed by BHP Billiton to mark their 100-year anniversary since the commencement of steel making in the Hunter region.

In commemoration of the Anzacs the walkway features silhouettes of soldiers, laser cut from 10mm thick weathering steel, specified to withstand the coastal wind load. These silhouettes are engraved with 3,860 family names of almost 11,000 known Hunter Valley men and women who served in the Australian Imperial Force, Royal Australian Navy, Australian Army Nursing Service and British and Commonwealth forces during World War 1 from 1914-1918.

EJE Architecture carried out the detailed design work, and lead architect Barney Collins said the historical significance of the project site inspired the walkway’s sinusoidal design.

“During the design phase, we looked at the history of the site and build location next to Memorial Drive, which was originally constructed in 1922 to pay tribute to the soldiers who fought in World War I,” Collins said.

“The design concept of what is commonly known as ‘the wave effect’ was drawn on the fact that DNA was used to identify the human remains of soldiers, and this process stood as the connection between the soldiers and their families.”

Constructed by Waeger Constructions and engineered by Northrop Engineers, the walkway has a structural design life of 70 years, as required by Newcastle City Council. Grade 316L stainless steel was specified due to its sustainable, corrosion resistance and ductile properties. The cliff top location of the walkway overlooking the Pacific Ocean was also a determining factor given the high wind and salt exposure.

ASSDA Sponsor Atlas Steels supplied 64 tonnes of stainless steel for the walkway including DN150 x 10.7mm, DN125 x 6.5mm, and DN65 x 5.1mm wall pipe; 200mm x 100mm x 6mm rectangular hollow sections and 100mm x 100mm x 5mm square hollow sections for the bridge section frames; and 16mm diameter round bar and 50 x 2mm and 50 x 3mm round tube for the handrails and balustrades.

Good scheduling and planning ensured on-time delivery of the stainless steel over a period of 14 weeks, which was sourced from three overseas mills. Positive material identification (PMI) testing was performed by the mills on all stainless steel supplied to ensure the specified grade of 316L was delivered.

Fabricated and installed by ASSDA Member and Accredited Fabricator SGM Construction & Fabrication, the 160m of stainless steel bridge sections consist of eight, 20m single spans (four under trusses and four over trusses) each weighing 6.5 tonnes. The frame of each section is fabricated from 12 square hollow sections welded to two rectangular hollow   sections, and the walking surface is laid over the frame. On either side of the truss, the wave-like effect was created by bending and rolling wall pipe to sweep above the frame for the over trusses and below the frame for the under trusses.

Seven Y-shaped precast concrete pylons up to 8.8m high and 3.4m wide, and two abutments, support the bridge sections of the walkway that reach up to 9m above the ground.

The decking of the walkway was laid with fibre-reinforced plastic, and being a non-structural component, was specified with a 44-year design life. The safety aspects of the bridge are completed with hand railings, which are welded on to the bridge trusses inside the curved pipe sections.

Over 760m of handrails and 600m of vertical balustrades cover the length of the bridge, specified with a maximum Ra value of 0.5. ASSDA Member Australian Pickling & Passivation Service was contracted to electropolish the balustrades and pickle and passivate the completed bridge sections. A purpose-built electropolishing unit, consisting of six baths, was set up to handle and achieve the specified finish of the 1.5m high x 6m long balustrade panels each weighing 180kg.

With an allotted fabrication period of only four months, SGM Fabrication & Construction manufactured the bridge sections using its 2000m2 workshop to full capacity to meet the critical deadline for Anzac Day.

As the walkway runs parallel to Memorial Drive, the main thoroughfare from King Edward Park to Merewether Beach, the erection of the pylons and installation of the bridge sections took place only during a 10-hour window over two nights to avoid prolonged temporary road closures.

Coastal undermining was a challenge for the structural engineers, however good design and construction ensured environmental protection of the sensitive coastal site to minimise erosion.

Mr Collins said the key to the project’s cost control and overall success was the engagement of local contractors.

“The direct involvement of each contractor’s Directors ensured seamless communication and full control of each project phase. The walkway is already an icon for Newcastle, and everyone who has worked on the project is thrilled over its success,” Collins said.

More than two million people visit Newcastle’s beaches every year, and the Newcastle Memorial Walk is already one of Australia’s most remarkable coastal walkways and a significant World War I tribute.

  

This article is featured in Australian Stainless Issue 55 (Winter 2015).

Images courtesy of Bryce Thomas.

Riverwalk Reborn

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.

Local stainless companies get a piece of the mining action

ASSDA member Australian Pickling & Passivation Service (APAPS) and ASSDA sponsor Sandvik Mining & Construction have been central to the expansion of a coal export port in North Queensland.

With Queensland coal exports forecast to increase to 250mtpa by 2015, the strength and durability of the state’s expanding coal transport infrastructure and rail systems is critical to ensuring export capacity.

This recent expansion required the manufacture of 300 three-piece conveyor frames using 40 tonnes of 316 grade stainless steel, specified to foil the port’s exposure to wind, rain, salt spray and abrasive dust.

Sandvik Mining & Construction manufactured the conveyor frames for the project, and APAPS pickled the frames before delivery to the terminal.

Stainless steel can corrode in service if there is contamination of the surface. Pickling involves the removal by chemical means of any high-temperature scale and any adjacent low chromium layer of metal from the surface of stainless steel.

The client requested that the stainless steel conveyor frames were pickled to achieve a product that would not rust. According to APAPS’s Director Richard Raper, ‘Pickling stainless steel removes all traces of burnt chromium caused by heat from welding and any iron contamination caused by handling and processing during fabrication.’ He added that several variables must be considered when pickling stainless steel, including the grade, surface finish, the size and shape of the structure and bath temperature.

Transported by road on B-double trucks from Mackay to the APAPS workshop in Newcastle, the conveyor frames arrived a dull grey colour and heavily soiled from anti-spatter and other contaminants. Pre-cleaning of the stainless steel was required prior to pickling as contamination on the surface can reduce the effect of pickling. The frames were sprayed using an Avesta 401 Cleaner and Callington Haven Brite Wash and left for 30 minutes before being high-pressure washed with hot water.

The immersion pickling method was used to pickle the conveyor frames. They were immersed in a nitric and hydrofluoric acid bath for approximately 1.5 hours, which APAPS’s own pickling technician determined following a number of inspections. Avesta Pickling Bath 302 was used at a temperature between 25-30°C. The frames were lifted from the bath and allowed to drain for 15 minutes before being washed down using high-pressure water.

APAPS’s pickling of the stainless steel by was central to ensuring the performance and durability of the conveyor frames and maximising their corrosion resistance. The treatment also produced a consistent and smooth finish with aesthetic appeal.

After the pickling treatment, the conveyor frames were strapped together in batches of five, with timber placed between the stainless steel and strapping. They were then transferred and loaded using a forklift with stainless steel slippers [covers] to protect the frames from cross-contamination. Due to the physical nature of the conveyor frames, only one layer of frames at a time could be placed on the truck deck, and these were tied down with web straps. Transportation took an average of 3 days between Newcastle and Mackay.

The project was completed in 10 weeks and delivered back to Mackay in stages. The APAPS team worked two shifts a day to complete the work on time for Sandvik.

Richard Raper says the project was a testament to APAPS’s membership of ASSDA, as it was the Association’s referral that won him the job.

‘This is a good showcase of how ASSDA members and Accredited fabricators can achieve great outcomes and how clients get what they expect when specifying stainless steel.’

Images courtesy of Australian Pickling & Passivation Service Pty Ltd.
This article is featured in Australian Stainless magazine issue 53, Autumn 2013.

Proven Strength in Stainless

Stainless steel is the material of choice to specify for severe weather conditions.

The overhead netting of Perth Zoo's Australian Wetlands and Penguin Plunge Exhibit was badly damaged when a severe hailstorm and winds of up to 128km/h swept through Perth in March 2010.

During the storm, a tree collapsed onto the netting which was made from a nylon material.

The original concept for this major renovation project was to use stainless steel overhead netting and painted or galvanised steel for the cabling and the majority of other supporting infrastructure components.

However, when ASSDA members Structural Dynamics was awarded subcontractor for the supply and installation of the new overhead netting system, it proposed using stainless steel for all components of the structure, including the cable tension system.

Working closely with Slatter Constructions (head contractor), Thinc Projects (project manager) and Pritchard Francis (structural engineers), stainless steel became the clear choice to provide strength and the crucial ability to withstand severe weather conditions.

Structural Dynamics Managing Director Darren Wills said the team agreed that specifying stainless steel would improve performance, product life cycle and reduce the risk of galvanic reaction.

‘Stainless steel materials break down at a much slower rate than galvanised materials,’ Wills said.

In terms of longevity and durability, stainless steel was the better option given the conditions of the local environment and fresh-water animals.

Slatter Constructions’ Project Manager Rob Murrell added that, on top of providing an aesthetic finish and prolonging the life of the enclosure, using stainless steel for the cables negated the need to ensure separation of different metal types.

Perth Zoo was convinced that stainless steel was the better long-term option and proceeded with stainless steel as the majority materials specification. With a life span of up to 20 years when compared with only up to 10 years using galvanised steel, the increased cost of using stainless was outweighed by the longevity of the product.

The new 91m long x 33m wide x 10m high netting and support structure was completed in early 2012, using the following stainless steel materials:

Backstay column support cables

  • 440m of 16mm and 19mm HAMMA Pro Stand 1x19 AISI316
  • 48 units of 16mm and 19mm Strudyna P2H Adjusters AISI 316

Netting structural support cables

  • 720m of 8mm and 10mm HAMMA Pro Stand 1x19 AISI316
  • 56 units of 8mm and 10mm Strudyna AM Adjusters AISI316

Netting support cables

  • 3900m of 5mm HAMMA x wire rope 7x19 AISI316

Netting

  • 5,400sqm of ClearMesh zoological netting AISI316
  • 15,200m of 1.6mm seizing wire 1x7 AISI304

Rodent proof barrier

  • 300m of 5mm stainless steel angle AISI316 3000m x 150mm x 5mm

Miscellaneous

  • 2,400m of 10mm threaded rod AISI316
  • 600 units of 10mm eye bolts AISI316
  • 600 units of 5mm turnbuckles AISI316

It was pivotal that the new cable structure could cope with extreme one-in-a-hundred year Perth storms, and the high tensile stainless steel structural cable components were ideal for this design parameter. Meeting a range of cable tensions, the HAMMA stainless steel cables installed are rigid to deal with high tensile loads, but also allow for some give to counter the effect of high winds and other harsh weather conditions. Their grade 316 stainless steel construction provides excellent corrosion resistance.

ClearMesh - often used in zoological enclosures globally - was applied to the overhead netting and netting mesh wall that separates the Wetlands from the Penguin Plunge Exhibit within the enclosure. With mesh openings of 2mm, the lightweight and flexible characteristics
of the ClearMesh display a transparent look that complements the landscaped environment and allows for give in case birds fly into the mesh.

Wills said the structure was designed to retain wildlife inside the enclosure and provide a close-to-natural environment for the Australian wetlands wildlife and penguins to thrive in. This resulted in an extremely high level of detail being specified, with stainless steel seizing
wire used every 5mm on the seams of the stainless netting. Over 38,000 hand seizes were performed by the Structural Dynamics team.

As the enclosure was an established site prior to the storm, Perth Zoo required that construction had limited impact on the existing landscaping to assist with animals being reintroduced to their former habitat. Murrell said careful planning between Structural Dynamics and Slatter Constructions ensured the works were completed without harm to the existing vegetation and surrounding areas.

Further construction and landscaping works included a new timber deck walkway for visitors, a limestone block wall and vermin barrier to the perimeter of the wetlands area, an upgraded filtrations system and refurbishment of the existing penguin pool and surrounds.

The renovated enclosure has since survived the June 2012 storm with winds of up to 140km/h, and the cable netting structure and supporting infrastructure today remains as built.

Images courtesy of Structural Dynamics.

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

Stainless Steel and Nickel - 100 Years of Working Together

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.

Stainless Bridges the Gap

The Go-Between Bridge

With 14,000 vehicles crossing Brisbane's Go-Between Bridge every day, stainless reinforcement is playing a vital structural role on Brisbane's first inner city bridge in over 40 years.

Formerly known as the Hale Street Link, the Go-Between Bridge connects Merivale and Montague Streets in West End to Coronation Drive and the Inner City Bypass in Milton.

Constructed as part of the Brisbane City Council’s TransApex plan, the Go-Between Bridge was designed to improve cross-river accessibility, reduce inner city traffic congestion, increase accessibility to Brisbane’s recreational and cultural precincts and cater for future residential developments in West End and South Brisbane.

The $338 million project commenced in 2008 and was built by the Hale Street Link Alliance (Bouygues Travaux Publics, MacMahon Holdings, Seymour Whyte Holding and Hyder Consulting).

The cantilever, box girder bridge stretches 274 metres over the Brisbane River and was built using stainless steel reinforcement with concrete foundations. Featuring a dedicated pedestrian and cyclist pathway, the Go-Between Bridge is 27 metres wide, with the main span measuring 117 metres.

ASSDA sponsor Valbruna Australia supplied 80 tonnes of grade 316L/1.4462 Reval® stainless steel in 12mm, 16mm, and 24mm reinforcement bar, which was used for the two major pile caps and north abutment of the bridge.

Valbruna Australia’s Managing Director, Ian Moffat, said stainless steel was specified for the critical elements of the bridge to minimise life cycle costs, improve structural integrity and corrosion resistance.

“Particularly being located in a marine environment, Reval® stainless in reinforced concrete is ideal to resist chlorides and pitting corrosion; it has an expected service life of 100 years in concrete,” Moffat said.

By specifying stainless, the designers were able to reduce the area in which stainless rebar was used in the structure because of its tensile strength being higher than carbon steel. In addition, using stainless steel reinforcement in concrete structures is stronger than carbon steel and will prevent material fatigue ensuring longevity for public infrastructure.

Moffat said Valbruna had 30% of stainless rebar already in stock, with the rest of the material having been shipped from their warehouse in Dubai and direct from their mill in Vicenza, Italy.

“Between the three locations, we were able to supply the stainless steel early and well within the specified timeframe,” Moffat said.
All Reval® stainless steel was produced and tested on site at the Acciaierie Valbruna S.p.A mill in Italy and manufactured to ISO 9001:2008 norms as certified by Lloyd’s Register Quality Assurance.

The Reval® stainless rebar was delivered to Neumann Steel in Currumbin for scheduling, cutting and bending.

A cut-to-length shear line machine was used, as well as a level off-coil machine to cut and bend the material into the finished product. All machines were cleaned before use to remove dust and carbon steel residue to avoid contamination of the stainless steel.

Neumann Steel’s Reinforcing Scheduler, Greg Prider, said the project was extremely complex and difficult to schedule.
“As the precast concrete units were manufactured at another site, we had tight tolerances to work with. It was critical to be precise in cutting and bending the stainless rebar to avoid unnecessary additional costs,” Prider said.

Following six weeks of scheduling, the stainless rebar was sent to the Brisbane Barge Berth, where precasting of the concrete units were assembled before transporting the modules direct to site by barge for installation.

Named after iconic Brisbane rock band The Go-Betweens, the Go-Between Bridge was completed and officially opened to traffic in July 2010.

This article is featured in Australian Stainless magazine, issue 51.

A Stainless Facelift for Surfers Paradise

Stainless is a key feature in the urban design and revamp of one of the Gold Coast's most iconic and vibrant tourist destinations.

The $25 million Surfers Foreshore Project was commissioned by the Gold Coast City Council (GCCC) to redevelop the beachfront area between Laycock Street and View Avenue in Surfers Paradise.

Aimed at improving infrastructure and visitor recreation, the new promenade features new lifeguard towers, amenity blocks, beach shelters, picnic areas with barbeques, and increased pedestrian and disability access to the beach.

Managing Contractor Abigroup Contractors Pty Ltd appointed ASSDA member and Accredited Fabricator J&T Mechanical Installation to fabricate and install the stainless steel architectural handrails and balustrades across stages 1, 2 and 3.

Trent Todd, J&T Mechanical Installation’s Director, said that with the handrails and balustrades being installed less than 30m from the shoreline, stainless steel was the only choice to withstand the harsh coastal environment to help resist tea staining and ensure long-term durability and performance.

A 2009 GCCC study in affiliation with Griffith University saw the GCCC adopt stainless steel as the default specification for structures with a design life of more than 19 years in foreshore zones.

This followed research results showing the material required lower maintenance and was the most effective in life cycle costs when compared with hot dipped galvanized (HDG) steel, paint systems and duplex systems using both HDG and paint.

At a total cost of approximately $80,000, the stainless steel handrails and balustrades span 1300m across the esplanade that fronts Surfers Paradise Beach.

Grade 316L stainless steel was specified for these elements of the project, which included 36 sheets of 10mm thick plate measuring 1500mm x 3000mm supplied by ASSDA member Allplates. ASSDA Sponsor STM Tube Mills Pty Ltd supplied 1300m of 50.8mm x 1.6mm thick tube. Another 3500m of 1/4” wire was also sourced for the balustrading.

All the flat and tube components including 124 stanchions were laser cut and folded by Allplates.

Stanchions and base plates were machine polished to 600 grit by ASSDA member and Accredited Fabricator Minnis & Samson to give the stainless steel an even polish and the stanchions a square edge. The stanchions were electropolished before being delivered back to J&T Mechanical Installation’s workshop for assembly.

J&T Mechanical Installation fabricated the top (50.8mm x 1.6mm tube) and bottom (folded channel, 4mm thick) rail frames with two vertical 16mm diameter solid round bar intermediate supports. Infill wires at 6.4mm diameter were positioned with swage fittings and lock nuts on each end to construct the vertical balustrades.

On site, J&T Mechanical Installation completed civil works prior to installation, including pre-drilling with the fasteners for the base plates to which the stanchions were then bolted. The rail frames were welded to the stanchions in 2.1m sections.

Following installation, a proprietary stainless steel cleaner was applied to remove any oxides, and a mild cleaner was followed to provide surface protection and inhibit corrosion.

Architectural feature lighting was installed to illuminate the pedestrian walkways at night.

The Surfers Foreshore Project was completed in April 2011 and today continues to thrive as the Gold Coast’s most popular entertainment precinct where city meets the surf.

Images courtesy of Allplates.

This article is featured in Australian Stainless magazine, issue 51.

Chimpanzee Sanctuary

Where Strength Meets Style

Innovation in zoo enclosure design is a key feature of the recently completed $7.5 million makeover of the Chimpanzee Sanctuary at Sydney’s Taronga Zoo.

The project brief was to create a chimpanzee habitat akin to their native home that would encourage social interaction and allow the zoo’s primate keepers to manage animal husbandry and the group’s changing demographic. The enclosure’s transparency and the ability to withstand the chimpanzee’s remarkable strength and intelligence were essential.

ASSDA member Ronstan Tensile Architecture was contracted by the builder, the Lipman Group, to be the specialist contractor for the technical design and installation of a mesh enclosure and non-climbable wall. Ronstan’s unique capability in tensile architecture and their technical expertise were a natural fit for this challenging project designed by Jackson Teece Architects.

The Sanctuary features the mesh separation paddock (similar to an aviary), at one end of the main exhibit. A non-climbable wall with a removable curtain, allows both spaces to function as one large paddock. This enables introductions of new chimpanzees into the compound and helps manage the apes’ complex behaviour patterns.

Ronstan Tensile Architecture’s General Manager, Rowan Murray, said the non-climbable wall structure was one of the most the challenging design aspects.

“The architect’s greatest challenge was to separate the chimpanzees physically, but still have them all in view in the paddock. We had to build a wall that was transparent, had openings of no more than 5mm to avoid chimpanzees putting their fingers in and climbing, and could withstand the strength of chimpanzees.” Mr Murray said.

The structural complexity of the non-climbable wall required 3D modelling to analyse design configurations and ensure structural integrity. Test panels of the non-climbable wall were fabricated and assessed in the chimpanzees’ temporary enclosure to determine which would offer the safest containment of the site and minimise visibility.

Mr Murray said the primary structure for the wall consists of a Ronstan supplied tensile cable net that supports semi-transparent perforated stainless steel panels.

“Most materials can be damaged, but the durability of stainless steel panels of certain perforation proved to be the right solution and important in the development of the overall design,” he said.

“The non-climbable wall had been designed with wall panels clamped directly to the enclosure mesh face. In a collaborative effort, we changed this to an independent cable net structure to remove the risk of having the final wall shape differ from that modelled, and in doing so, avoided the risk of panel geometry differing from the complex 10 degree incline necessary for non-climbability. This also ensured uniform set out and fixing methods, more consistent panel shapes and allowed the panel geometry to drive the wall structure rather than this being determined by other elements.”

ASSDA member, Locker Group, supplied the grade 304 stainless steel panels, which were perforated to 50%. A black painted finish was applied before installation.

With stringent performance characteristics to adhere to, including long-term corrosion resistance and aesthetics, Carl Stahl X-Tend stainless steel mesh was specified for the separation enclosure and the removable curtain within the non-climbable wall. The stainless steel mesh was blackened using an electrolytic process to increase transparency of the enclosure.

Trevor Williams, Lead Consultant of Jackson Teece and Project Architect for the development, said materials selection was critical in delivering the aesthetic appeal and longevity of the enclosure.

“We spoke with Ronstan Tensile Architecture for technical design advice in the early stages of the project. There were various other types of meshes that were a possibility but, being a dynamic structure, alternate materials were far too rigid and not as flexible as the Carl Stahl X-Tend stainless steel mesh. I don’t think we could have achieved this outcome with any other mesh,” Mr Williams said.

“The stainless steel will have a longer life in the aggressive south-facing coastal environment. The blackened mesh has a fantastic form and from an architectural point of view, has achieved an organic appearance.”

Ronstan Tensile Architecture’s contribution to the project, including the tensile mesh enclosure and non-climbable wall, cost about $1.2 million and took 16 weeks to construct.

Mr Murray said the stainless steel demonstrates a great mix of strength and transparency, and the end tensile result is very forgiving.

“Achieving the architectural intent involved complex modelling and finite analysis of the mesh form to ensure the surrounding structures could be designed to support the enclosure loads. Ronstan is absolutely rapt with the state-of-the-art structure,” he said.

The paddock was completely re-landscaped and the impressive exhibit also now features several climbing platforms at varying heights of up to 12 metres, and a 180 kilogram hammock for the chimpanzees to enjoy.

The 17 lucky Taronga Zoo chimpanzees moved in to their renovated home in late September 2011.

QUANTITIES AND GRADES OF STAINLESS STEEL USED

›    Mesh enclosure 770m² of 3mm Ø x 60mm blackened stainless steel, grade 316 Carl Stahl X-Tend mesh.
›    Non-climbable wall facade 140m² of grade 304 stainless steel perforated to 50%, with a black painted finish.
›    Cables 1x19 construction 8mm, 12mm and 22mm diameter, grade 316 stainless steel cables. The stainless steel cable end fittings and  components were polished and passivated prior to installation.

Images courtesy of Ronstan Tensile Architecture.

This article features in Australian Stainless magazine - Issue 50, Summer 2011/12.

Whole of life costing

19 years plus points to stainless

A fresh focus on whole-of-life costing at Gold Coast City Council has led to the specification of stainless steel for long-term structures in the foreshore zone.

The philosophy, which was adopted following the publication of a study by Griffith University and GCCC, is likely to have flow on effects to other councils and government bodies.

GCCC’s co-ordinator of technical governance Paul Conolly said the seed was planted in 1998 when Council’s Technical Services Branch specified stainless steel for a modular toilet structure in a foreshore zone park. The material was deemed at the time to be cost prohibitive on a capital expenditure basis but the process sparked an interest in lifecycle costing.

Mr Conolly said Council’s growing interest in lifecycle costing, combined with an expectation among locals and tourists that public facilities showcase a ‘resort style’ finish, had brought the focus back to stainless steel in recent years. “There has been a clear trend towards lighter, more open structures for public facilities and these lend themselves to steel work,” he said. “A lot of our public facilities are in the foreshore zone and some materials weren’t performing as well as we wanted, so we started to look at corrosion issues and how to best manage this. We started using stainless steel for critical elements, such as joint interfaces for concrete works; bolts, brackets and cleats for boardwalks; and for high use facilities such as rubbish bins.

“Our observations led us to believe that stainless was the way to go in the foreshore zone, but we had no tangible justification which the designers could use to validate the decision for our asset custodians. We needed clear evidence to prove the initial cost of stainless steel was justified over the life of the structures.”

Griffith University scholarship student Jordan Cocks was called on to research the topic in conjunction with industry affiliate GCCC as partial fulfilment of his Bachelor of Civil Engineering.
Mr Cocks investigated multiple structural scenarios from the perspective of what would represent the most cost-effective solution: hot dipped galvanized (HDG) steel, paint systems, duplex systems using both HDG and paint, or stainless steel.

The result was a report containing a design guide, a life cycle cost analysis and a life cycle costing spreadsheet for structures in the foreshore zone. The report indicates stainless steel is a viable option based on cost alone for structures with a design life greater than 19 years. Conversely, the study indicates a HDG coating would theoretically have a life span of 14 years, leaving the exposed steel subject to rapid corrosion unless protected by an increasingly costly maintenance regime.

Mr Conolly said the report had delivered a workable tool enabling designers to input various parameters, such as current prices and design life, producing a guide for selection of the appropriate material or finishes based around optimising whole-of-life costs.

Similar principles were used to shift the specification of a park arbour in Broadbeach towards stainless steel. The material was essential due to the warm, humid environment of the foreshore, regular spraying with water and fertiliser, and the fact that the arbour would have plants growing over it that would take many years to fully establish. The report has now been used to guide material selection for a number of projects, including toilet blocks in Jacobs Well, Miami (pictured) and Burleigh Heads.

“With these projects, we have gone to the asset custodians and our first question was – what is the design life?” Mr Conolly said. “The report has helped reinforce the need for a ‘cradle to grave’ approach to responsible and sustainable asset management encompassing all stakeholders. This includes not just the designer and asset custodian but all the operational and maintenance personnel involved with a structure.

“For stainless steel structures, the asset custodians now recognise that to retain an asset over the long-term and to satisfy the whole of life cost advantage there must be regular wash downs as part of the maintenance program. The higher initial construction costs are offset by the lower cost regular wash downs which form the major component in the new maintenance regimes. The buildings are also being designed to be hosed from ceiling to floor. The overall process has really helped improve the relationship between the asset custodians, designers and maintenance staff.”

Mr Conolly said the report had also been used to promote the use of stainless steel in playground equipment and shade sail structures. “It is just a matter of making that little leap towards recognising the whole-of-life cost and ensuring delivery of a durable product – it’s not rocket science, just common sense when you think about it.”

GCCC is also now favouring ASSDA Accredited Fabricators and looking to ASSDA to provide third party technical expertise or adjudication should conflicts arise relating to material performance. The ASSDA Accreditation Scheme requires fabricators to conform to stringent standards of competence, training and education and encourages a consistently high standard through industry self-regulation.

ASSDA Executive Director Richard Matheson said GCCC’s decision to favour ASSDA Accredited Fabricators and specify stainless steel in the foreshore zone was a welcome one. “I believe we will see this initiative mirrored by other councils and government bodies in the near future,” Mr Matheson said.

“There is no doubt that informed specification and quality fabrication by people who know and understand the material will offer long-term cost savings and extend the life of the product. This is why ASSDA places so much emphasis on education and technical expertise – Councils and other government bodies need to get it right the first time and ensure value for money for their constituents.”

Mr Conolly said for long term structures, stainless steel was becoming the default specification in the foreshore zone and the trend was even moving inland.

“We’re asking the question: what will look and perform best from cradle to grave? It’s making people think differently,” he said.

Download the the final report here (4.6MB) - Whole of Life Cost Comparison and Cost Benefit Analysis for Steel Structures Constructed in the Foreshore Zone.

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This article featured in Australian Stainless magazine - Issue 48, Autumn 2011.

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.