SUMMER 2016/17 Elizabeth Quay Pedestrian Bridge, Perth. Photo courtesy of Stirlings Australia.
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AUSTRALIAN STAINLESS STEEL DEVELOPMENT ASSOCIATION
STAI N LESS STEEL SHINES I N PERTH’S ELIZ ABETH 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 2 AUSTRALIAN STAINLESS 58 www.assda.asn.au
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
Photo courtesy of Stirlings Australia. 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. ASSDA MEMBER CONTACTS: Stirlings Australia Michael Stirling +61 8 9366 6700 email@example.com www.stirlingsaustralia.com.au Unifab Welding Pani Himona, Director +61 8 9494 1774 firstname.lastname@example.org www.unifabwelding.com.au Valbruna Australia Greg Childs, State Manager email@example.com Scott Ford, Special Products Manager firstname.lastname@example.org +61 7 3807 9733 www.valbruna.com.au Vulcan Stainless Clinton Howe, Business Unit Leader WA +61 8 9412 5600 email@example.com www.vulcansteel.com.au www.assda.asn.au
AUSTRALIAN STAINLESS 58 3
GUIDELINES TO USI NG A S / NZS 1554.6 FOR WELDING STAI NLESS STEEL Using AS/NZS 1554.6 effectively means rather more than requiring “Weld finishing to AS/NZS 1554.6”. The standard is an effective way to get the finish you want or need on stainless steel structures. This guide should help you to nominate the quality of weld to the standard.
What is this standard? This standard is for welding any non-pressure stainless steel equipment and when it was first drafted in 1994, its structure followed that of Part 1 dealing with carbon steel. A major revision in 2012 removed redundant text, expanded the good workmanship guidelines and brought the weld assessment and finishing processing up-to-date, while including guidance on precautions to minimise risk of failure from vibration. The assessment section includes mandatory limits to weld defects and now includes optional features such as level of heat tint and surface roughness that may be specified by the principal or owner. AS/NZS 1554.6 is a mixture of mandatory requirements and recommendations with shopping lists of possibilities. In particular, the post-weld treatment provides a number of possible processes and results, and specifying the option desired will minimise cost and frustration and deliver the result required. As an example of mandatory requirements, there are strict requirements for personnel qualifications, which are difficult to address retrospectively.
The raw product of welded fabrication Figure 1 is typical of a routine TIG butt weld of two thin 316 stainless steel sheets and displays a rainbow of colours on the surface. The colours are caused by optical interference of reflections from the front and back of the heat formed oxide layer - just like reflections in an oil film on water. The unprotective iron-rich oxide layer can be seen in the dark colours and can reduce the corrosion resistance of a 316 to below that of a 12% chromium stainless steel. They must be removed along with a small amount of steel underneath them, where the chromium has been depleted during welding. Specifying their removal is covered later in this article. Let’s start with Section 6, because that is where the weld quality is assessed.
Figure 1: TIG butt weld
Classifcation of welds Welds are classified as Category 1 (structural) or Category 2 (nonstructural). Category 1 welds have a subset Fatigue Applications (FA), where vibration and fatigue failures may be an issue. The main difference is that Category 1 and Category FA welds require external visual inspection plus sub-surface inspection by radiography or ultrasonics. The permitted levels of sub-surface defects are listed in Tables 6.3.2(A) and 6.3.2(B) for structural and fatigue classifications respectively. However, all of the Categories 1, 2 and FA are assessed against three levels of surface defects revealed by visual and liquid penetrant inspection.
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The permitted defect sizes are set out in Table 6.3.2 and are grouped under three levels: A: No defects and used for critical structural, aesthetic or corrosive service; B: High quality for general and non-critical aesthetic uses but may have minor defects that allow corrosives to accumulate in very aggressive environments; C: Hidden locations or areas with low stress and benign conditions. The temptation is to specify Level A for everything, but this may raise costs unnecessarily without adding to durability. Often Level B is very satisfactory. For instance, the ASSDA tea staining requirement of weld quality is Category 2, Level B. Category FA welds require compliance to Level A assessment of surface defects plus restrictions on the angle between fillet weld tangents and the adjoining stainless steel surface. This restriction supplements the 1 in 4 slope in section thickness changes set out elsewhere in the standard. Table 6.3.1(B) gives the level of sub-surface defects permitted. It applies only for FA requirements.
Post-weld surface finishing The standard also provides options for post-weld and surface finishing. Welds may be treated mechanically with abrasives, or chemically (or electrochemically). Any of these finishes can be called up for Condition I and Condition II, but the defining feature of Condition I is that the weld bead must be ground flush. This strip polishing is common in tank fabrication for the food and beverage industries. It removes the heat tint and the chrome depleted layer beneath it without using pickling acids, but it also improves cleanability by removing the weld bead with its inherent unevenness. In vibrating applications, the mechanical removal also decreases the risk of stress concentration along the stiffening line of a weld bead. The standard also allows stainless steel brushing to remove surface deposits or else for the surface to be left “as welded”. These options are included in Condition III. Table 6.2.1 summarises the paths to the surface conditions and Table 6.3.3 provides the acceptance criteria based on discolouration, average surface roughness Ra and maximum surface roughness (Rmax). In the 2012 version, the criteria are largely “specified by the principal”, but Condition I and II for discolouration are tied to the AWS D18.2 colour charts of heat tint which match Sandvik and Nickel Institute work confirming that a pale straw colour caused no detectable change in corrosion resistance. There are non-mandatory notes that transverse surface roughness should be <0.5μm Ra and clean cut for corrosive service [as for surface 2K in EN 10088.2] and about the applicability of Rmax to cleanability in hygienic service. Amongst other variables, the grit size will determine the roughness (Ra and Rmax) and hence the asabraded corrosion resistance and cleanability. Condition III does not have acceptance criteria. Tables 1 and 2 (opposite) are a guide to the use of category, class and condition (used both for treatments applied and assessment results) and relate them to post-weld processes.
Other treatments While mechanical abrasion will remove heat tint and the chrome depleted layer, it will expose manganese sulphide inclusions which are points for corrosion initiation. It may also leave metal flakes on the surface, which provide crevice corrosion sites.
A, B, C
Visual and dye 2
A, B, C
For any specific class, we can have optional assessment of colour, Ra and/or Rmax with different criteria for Result Conditions I, II and III.
VISUAL DEFECT CLASSES PASSIVATE
TABLE 2: PROCESS CONDITIONS AND WHAT THEY MAY INVOLVE
TABLE 1: CATEGORY AND DEFECT CLASS
*Not all processes are listed. (Y) means this process may be used.
Pickling [Section 6.2.3(a)] using a nitric/hydrofluoric acid bath or paste will remove metal flakes and manganese sulphide inclusions. Pickling a non-abraded weld area will not significantly change the surface roughness, but will give similar corrosion resistance to an abraded and pickled surface. If the use of hydrofluoric acid is difficult, then a nitric acid passivation process of an abraded surface will improve the passive film, remove the inclusions, but not any metal flakes. A passivation treatment will strengthen the passive film even of a pickled surface. A nitric-only treatment is not effective on a heat tinted surface. Other modifications of Conditions I and II include electropolishing [6.2.3(b)] or, more recently, electrocleaning [6.2.3(c)]. Both apply a current which dissolves the surface either in a bath (electropolishing) or on site (electrocleaning). The mechanically polished bar illustrated in Figure 2 had an Ra of ~0.7μm before electrolishing, but 0.2μm less afterwards and with a much brighter appearance that also has a thicker passive film. Electrocleaning is a manual process, and while it can produce a very strong passive film, its results depend on the expertise of the operator.
chromium layer beneath, i.e. it will not restore the corrosion resistance. Abrasive polishing, linishing, grinding [6.2.3(e)] or even blasting [6.2.3(f)] can remove heat tint and the low chromium layer while leaving some weld reinforcement, but a nitric acid passivation process may be required afterwards. In addition, the surface may be too rough for good cleanability or smooth appearance. Under Condition II, one treatment to provide oxide-free welds for pipes and tubes is the use of inert gas purging with low (tens of ppm) oxygen levels. Apart from the weld inspection, Section 5 of the standard has multiple recommendations for excellent fabrication including heat input, interpass temperatures, avoidance of arc strikes and welding under adverse weather conditions, to name a few. There are also mandatory requirements (the “shall” clauses) on tack weld size, weld depth to width ratio, thinning of metal when dressing welds and even chloride limits in leak test water. The standard is detailed and requires some study for those wishing to produce good welds compliant to the relevant sections of AS/NZS 1554.6 and applicable to the application or structure under consideration.
Figure 3: Longitudinal weld in stainless steel pipe Figure 2: Mechanically polished bar with later electropolish
Condition II finishes include simple pickling (HF/HNO3), electropolishing (although often with a prior pickle to remove non-conductive weld scales) and electrocleaning for site operations. The longitudinal weld in the pipe (refer to Figure 3) still has weld reinforcement, but is chemically clean. The black lines parallel to the weld have not been affected by the acid pickling and are probably due to cracked oils not removed by solvents prior to welding. Post-pickling passivation is also included in this Condition II suite of treatments. The mechanical treatment of heat tint by stainless steel brushing [6.2.3(d)] simply burnishes the surface and does not remove the low
Conclusion The specification of weld quality requires an understanding of mechanical and chemical processes used to produce a smooth and clean surface suitable for the specific application. The standard provides a shopping list to accurately specify exactly what you want. Respecting that intent will lead to the greatest productivity in delivering the structure.
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AUSTRALIAN STAINLESS 58 5
I N NOVATIVE URBAN DESIGN Stunning stainless steel creations by ASSDA Member Draffin Street Furniture have delivered the contemporary edge required by the rising urban metropolis of Ringwood, Victoria.
relate to the proposed scale and vision for Ringwood. UI approached industrial furniture designer Andrew Gibbs to design a distinctive suite of street furniture and urban infrastructure that would meet his vision.
Working in collaboration with a team of urban architects and designers, Draffin Street Furniture crafted a suite of custom urban street furniture for the Eastland Shopping Centre in Ringwood.
Australian Native Landscapes (ANL) who was commissioned by UI to construct the project, including acquiring and installing the furniture elements for the Ringwood development, contacted Draffin Street Furniture to bring Andrew’s design concepts to life.
The Eastland Shopping Centre is located within a major transport network and services a large area of Melbourne’s eastern growth corridor. The integration of sustainable development within Ringwood is creating a sought after urban destination with a contemporary lifestyle. As such, its development is a consciously considered endeavour that is geared to meet the specific needs of its growing population.
Draffin Street Furniture worked in collaboration with Andrew to develop his unique furniture designs and generate physical manifestations that met the design brief. Draffin was able to produce an amazing result within a difficult timeframe, constructing an innovative and unique collection of urban infrastructure from his very complex and technical designs.
Funded by Maroondah City Council, landscape architectural firm Urban Initiatives (UI) was commissioned to generate a design vocabulary that would establish a consistent suite of street furniture and treatments that
Comprised of a series of seat benches, both backed and backless, bicycle racks, tree surrounds and waste receptacle surrounds, the Ringwood furniture suite is constructed primarily of grade 316 stainless steel. Using stainless steel plate ranging from 3mm to 6mm thick and 100x10mm flat bar supplied by ASSDA Sponsors Dalsteel Metals and Outokumpu, Draffin Street Furniture fabricated the custommade furniture suite and performed the mechanical finishing inhouse to Ra<0.5. The furniture was further pickled, passivated and electropolished by ASSDA Member MME Surface Finishing to ensure maximum protection against corrosion in a dense metropolis area. Draffin Street Furniture’s Director Ian Draffin said the vast majority of street furniture and other public urban infrastructure going into the Melbourne CBD area is now trending towards stainless steel as a default specification. While there is a high capital cost initially, the benefits of using stainless steel is unmatched in its material performance and reduction in ongoing maintenance and life-cycle costs. Ensuring sleek, modern aesthetics as well as durability, the choice of stainless steel ensures innovative urban infrastructure will remain functional and attractive for years to come. This is an abridged version of a story that first appeared in Outdoor Design Source. ASSDA MEMBER CONTACTS: Dalsteel Metals Troy Harris, Office Manager +61 3 8787 5600 firstname.lastname@example.org www.dalsteel.com.au Draffin Street Furniture Ian Draffin, Director +61 3 9720 1033 email@example.com www.draffin.com.au MME Surface Finishing Gerard Mulcahy, Managing Director +61 3 9775 1620 firstname.lastname@example.org www.mme.com.au Outokumpu Mark Armitage, National Sales Manager +61 3 9369 3344 email@example.com www.outokumpu.com/australia
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ST YLISH LI NES Stainless steel continues to deliver a strong and enduring reputation for visual appeal and structural performance in commercial applications. Perth’s Cockburn Health and Community Facility features over 300m of internal and external stainless steel handrails and balustrades fabricated and installed by ASSDA Member and Accredited Fabricator, Balustrading WA. The extensive use of stainless steel in the integrated medical and health centre complements the state-of-the-art building and quality services offered to the local community. ASSDA Sponsors Austral Wright Metals and Vulcan Stainless supplied grade 316 stainlesss steel throughout including for the main vertical balusters, which measure 10mm thick, and are 150mm wide at the bottom tapering to 100mm wide at the top. Stainless steel brackets were custom made to support the balustrades and stainless steel spider fittings were bolted to carry the 13.5mm glass sheets. The handrails were manufactured from 50mm diameter stainless steel round tube. All stainless steel components were specified with a 320 grit satin finish, and passivated by Balustrading WA prior to installation for maximum corrosion resistance.
ASSDA MEMBER/ACCREDITED FABRICATOR CONTACTS: Austral Wright Metals Rodney Alchin, State Manager +61 8 9258 2600 firstname.lastname@example.org www.australwright.com.au Balustrading WA Dave Hopkins, Operations Director +61 8 9208 2900 email@example.com www.balustradingwa.com.au Vulcan Stainless Clinton Howe, Business Unit Leader WA +61 8 9412 5600 firstname.lastname@example.org www.vulcansteel.com.au
The bespoke stainless steel balustrade and glass design offers stylish lines, spaciousness and unobtrusive views both in the facility’s internal voids and on the external balconies. Stainless steel was specified not just for its aesthetic appeal, but also for its corrosion resistant properties. The facility’s exposure to a salt air environment being located less than 10km from the Western Australian coastline makes stainless steel the material of choice to resist tea staining and provide long-term durability and performance, particularly for the external applications.
Minimal maintenance is required, with a monthly wash down using soap or a mild detergent recommended to remove any deposits that can contribute to surface discolouration and ultimately corrosion. Offering maximum durability, safety protection, visual appeal and style, the stainless steel architectural features of the Cockburn Health and Community Facility showcase an impressive everyday application of the material.
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VALE PETER MATHESON It is with deep sadness and regret to share the news that in September 2016, Mr Peter Matheson passed away. A civil engineer by trade, Peter was heavily involved in the nickel, cobalt and stainless steel industries, having spent over 40 years in technical, operational and corporate management roles in the resources sector. Peter was part of the original Australian team evolving concepts for Queensland Nickelâ€™s lateritic nickel project in 1969 and was continuously associated with the Queensland Nickel Project, including leading the project, until the establishment of his own company, PJ Matheson Resources Consultancy (PJMRC) in 1990. Amongst a broad range of nickel, cobalt and stainless steel pursuits, PJMRC played a pivotal role in the establishment of the Australian Stainless Steel Development Association (ASSDA), having started the discussion of a stainless steel association with Jim Howard (BHP Stainless). Following a feasibility study, ASSDA was incorporated with 30 members in 1992, and PJMRC provided the Secretariat services for the association until 2007 when it was succeeded by RJ Matheson Consultants. Peter provided invaluable commitment, support and expertise to ASSDA and was ASSDAâ€™s Company Secretary from its incorporation. Peter will be fondly missed and always remembered.
ABOUT ASSDA The Australian Stainless Steel Development Association (ASSDA) is a not-for-profit industry group that aims to increase the consumption of stainless steel in Australia. Established in 1992, ASSDA represents more than 150 member companies representing the stainless steel spectrum, including overseas mills, stockists and distributors, fabricators, engineering consultants, end-users and service providers. ASSDA aims to foster the understanding and use of stainless steel in Australia by developing the competence and efficiency of the industry through promotion, education and training, the provision of adequate technical advice and industry accreditation. ASSDA could not continue without the valuable support of its sponsors and members, who work with ASSDA to grow the market for stainless steel. www.assda.asn.au
AUSTRALIAN STAINLESS STEEL DEVELOPMENT ASSOCIATION
ASSDA SPONSORS 1
ASSDA SPONSORS 2 Midway Metals, Stoddart Manufacturing, Viraj Profiles Ltd., YC Inox Co., Ltd. ASSDA SPONSORS 3 Allmate International Co. Limited, Austral Wright Metals, Australian Stainless Distributors, Dalsteel Metals, Froch Stainless, Metal Centre Australia, Prochem Pipeline Products, Sanwa, Valbruna Australia. is proudly brought to you by the Australian Stainless Steel Development Association (ASSDA).
MORE INFORMATION Enquiries for further information on any material presented in this publication should be directed to ASSDA: Level 9, 167 Eagle Street T +61 7 3220 0722 Brisbane QLD 4000 AUSTRALIA E email@example.com www.assda.asn.au EDITORIAL Contributions of story ideas specialising in stainless steel and its applications are welcome from members of ASSDA. ADVERTISING Advertise in the only publication that targets more than 6,000 readers in the Australian stainless steel industry. Rates available at www.assda.asn.au. CONTACT Lissel Pilcher, ASSDA Communications Manager: firstname.lastname@example.org. DISCLAIMER ASSDA sources articles and advertisements from a variety of contributors and accordingly does not accept responsibility for the accuracy of the contents of this publication nor the suitability of specific applications referred to herein for any particular use. Competent advice should be sought before acting on any matter contained in this publication.
Specialising in stainless steel and its applications. Feature articles include Perth's Elizabeth Quay Pedestrian Bridge, Guidelines to Using...
Published on Dec 12, 2016
Specialising in stainless steel and its applications. Feature articles include Perth's Elizabeth Quay Pedestrian Bridge, Guidelines to Using...