Australian Stainless is a leading industry magazine devoted to showcasing the unique diversity and durability of stainless steel. Since its inception in 1993, Australian Stainless has assisted and encouraged specifiers and end users of stainless steel, with a focus on local fabrication.

For 17 years, Australian Stainless has been enjoyed by more than 8,000 readers across the country. In October 2009, Australian Stainless Online was launched to provide a readily available live news feed to a wider audience around the world. Australian Stainless is published by the Australian Stainless Steel Development Association (ASSDA), a non-profit industry group that aims to increase the consumption of stainless steel in Australia, through publication, education, accreditation and more.

To find out more about ASSDA and its services CLICK HERE or call (+61) 07 3220 0722.

'Remaining Competitive and Profitable' by James Johnson, Millatec Pty Ltd

Now is the time as an owner of a small or medium enterprise to move back into the coalface and be involved in all facets of your business. As a business owner, no one spends less money, identifies opportunities to improve productivity more or reduces waste better than you.

In the current economic climate it seems especially pertinent to discuss tools that can help you remain competitive and achieve break-even or be profitable.

The four key areas are:

1. Financials
2. Human resources
3. Marketing
4. Systemisation

Controlling your finances

When it comes to managing your finances, structure is vital. It is imperative that you plan your cash flow on a week-to-week basis to ensure debts can be paid when due. Ensure tax liabilities are allowed for. If you can’t meet your payment dates, talk to your creditors or the ATO: most will work with you, but they will take action if you are not open and honest.

To effectively monitor spending and avoid unexpected cash flow shortfalls, your financial reporting needs to be up-to-date. An ideal target is end of month plus 10 working days. To ensure reporting and recording is useful, filing of all financial transactions – including accruals – is vital.

A network of support is fundamental to the sustainability of your business. It is important to establish and maintain an open and honest relationship with your bank – during times of profit and of loss. The bank will understand the long-term fluctuations of your business and will be your best source of information on current services that suit your needs. Remember, banks do not want to see you go out of business – they will help you stay afloat.

For example, they have developed a range of new products to help with cash flow.

The current economic climate is a great time to negotiate for better deals – from freight to materials – and it is an ideal time to negotiate new leases.

Human resources: maximising productivity

Employees are the bones of your company. Have high expectations of your staff and make them known. Just as important as setting a high standard of work is letting your staff do their job and being flexible enough to make them want to stay. At the same time it is advantageous to not have any staff member who you are afraid to lose: no one should be irreplaceable.

A large part of managing human resources is managing risk. Employee training is invested time and money. Maintaining low staff turnover means retention of knowledge within the company and makes thorough training a valuable investment.

Marketing: sending the right message

If you want to maintain and grow sales, first and foremost be a marketing company. Invest in marketing as you would a new machine: work out the investment and expected return and research what is right for your business.

It is a great time for change so try the things that you have been putting off during busy periods.

The key is remembering that sales must lead production, and production must support the promise. This is a constant battle: they both need – and work just as hard as- the other. This needs to be reinforced daily.

Systemisation

Linking systems together means you maintain control of the business. Report and record weekly, monthly and quarterly. This not only helps in tracking financial movements but also ensures that in the instance of staff absence, the system will remain functional.

Linking the following systems is a good place to start:

• Quoting (capture all costs)
• Processing orders (no job starts without a written PO)
• Producing job cards
• Purchase orders (nothing gets in without one)
• Time capture (measure productivity)
• Stock
• Invoicing (nothing gets out without one)
• Financial accounting

If you have had a crippling 12 months, it is not too late to recover and come out stronger, wiser and more profitable.

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

For stainless apprentices

At the beginning of 2008, ASSDA was successful in its application for funding from the Federal Government for a project focused on the integration of e-learning into industry. The funding has seen ASSDA create a Workforce Development Strategy and a Flexible Learning Delivery Pathway incorporating e-learning, with plans to develop an additional e-learning module titled Practical Skills of Surface Treatment to complement the existing Gas Tungsten Arc Welding Module.

The Workforce Development Strategy provides an industry-wide framework in which to address the workforce challenges for the stainless steel industry: skills shortages, staff retention, knowledge retention. This document assisted ASSDA in defining what the industry requires in training, skills development and the retention of employees.

The body of the project sees ASSDA working in conjunction with SkillsTech Australia and multiple industry partners to develop e-learning as a form of theory training for apprentices aiming to acquire their qualification in stainless steel fabrication.

ASSDA created a Flexible Learning Delivery Pathway that gives apprentices and employers the choice of conducting training both online and within the workplace. This form of training is beneficial to the apprentices as they are able to work at their own pace, in a location of their choice and in a nonthreatening learning environment. For the employer the pathway is economical as the apprentice can conduct their study in the workplace, therefore reducing time spent away from the workplace.

Using ASSDA’s Stainless Steel Specialist Course and existing resources within the TAFE system, SkillsTech Australia has developed an e-learning system based on the required competencies for a qualification in fabrication, with a particular focus on the unique requirements of working with stainless steel. These training modules offer learning through video, audio, text, images and interactives that are interesting to the apprentice whilst teaching them the underpinning knowledge they require to develop a skill.

In March 2009, 12 apprentices were inducted into the e-learning program for Stage 1a at SkillsTech. This stage is now complete and feedback from the apprentices has been extremely positive. Stage 1b has now commenced and will see the apprentices training solely within the workplace with a workplace mentor to oversee their theory training and instruct them in their practical experience.

This is an exciting development aimed at positioning e-learning as the training method of choice within the stainless steel industry and will help meet ASSDA’s goal of building a strong workforce with a focus on quality and innovation.

If you are interested in viewing the Workforce Development Strategy or learning more about the learning options becoming available for apprentices, call ASSDA on (07) 3220 0722.

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

Combining Strength and Style

Melbourne based designer Pierre Le Roux began working with steel 15 years ago, more recently with stainless. “I love the high-tech, reflective quality of stainless,” he said.

Le Roux’s popular custom made wine rack design has attracted clients from both retail and domestic markets. Often doubling as a wallscreen, the unique rack is fabricated from grade 304, 3mm stainless steel sheet supplied by ASSDA member Dalsteel Metals. Each bottle holder was hand polished to achieve a personal finish.

Le Roux’s company produces custom made stainless pieces including sculpture, architectural and landscape features. Stainless domestic furniture and screening is becoming increasingly sought after and demand is largely surpassing supply. “The most common thing people say to me is that there’s just nothing out there, so they come for something unique,” Mr Le Roux said.

Creating one-off pieces to meet client specification means customer satisfaction and artistic flexibility. “This makes for a very rewarding profession,” said Le Roux.

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

Aussie Icon Immortalised in Stainless

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

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

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

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

New Potential for Mirror Finish

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

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

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

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

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

Ecologically Sustainable Stainless Design

With the population boom leaving less open space available for traditional garden beds, stainless steel is helping to reintroduce Mother Nature to an increasingly unnatural environment. Ecologically sustainable design (ESD) promotes the use of existing resources to maintain biological balance. This allows for natural light and ventilation, reduced energy usage, water consumption and greenhouse gas emissions. The need for this type of specification is so apparent that the Government has established the Green Building Council of Australia (GBA) to advocate sustainable property development.

City of Melbourne was among the first to demonstrate ESD in Australia, with its own office building Council House No.2 (CH2). Green features such as natural lighting and temperature control earned CH2 the first GBA six-star Green Star Certified rating.

Among CH2’s green features is vertical landscaping created by ASSDA Member Ronstan Architectural. The specialist tensile contractors at Ronstan developed support systems for these gardens, fixing grade 316 stainless mesh and cables to the building’s exterior. Ronstan’s Rowan Murray said the benefits of green façades are now widely acknowledged. “Many new buildings include elements of active and passive solar design and have some sort of façade as a physical shade.

Using plants as a shade element is becoming increasingly popular and there are opportunities for the stainless steel industry to provide essential structure as a platform for plant growth,” he said. ‘Living walls’ can be more beneficial than conventional shading systems, both economically and environmentally. The plant’s ability to cool via evapotranspiration provides natural insulation, lowering the building’s running costs, while producing oxygen at the same time. “This in itself provides a direct social and psychological benefit to the building occupants, driving people to engage with the building,” Mr Murray said.

“People actually enjoy the close proximity to plant life and stainless steel plays a big part in making this possible,” he said. Mr Murray said design considerations are important when specifying for this type of application, particularly “dead weight” from suspended sheet and plant matte, wind and rain force, but careful design ensures an efficient lightweight stainless solution. Specifying ESD is also beneficial to your budget.

“We love to see stainless used in intelligent ways with façades and the good news is that despite the current climate we are gradually seeing developers begin to take a more responsible approach to the upfront cost of ESD,” Mr Murray said. A recent GBA report denotes the value in green features, such as stainless façades, claiming the study proved that “green buildings make occupants healthy, wealthy and wise”. GBA recently awarded its 100^th green star to a sustainable interior design at Stockland Head Office in Sydney.

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

Stainless protects old for young

Historic remnants from the original Australian Hotel site in The Rocks will be preserved for future generations by stainless steel grillage platforms. ASSDA Accredited Fabricator Paige Stainless supplied and fitted the platforms for Auswave Products Pty Ltd as part of the site’s recent redevelopment.

The sandstone ruins, which date from the 1800s, are now on display within the recently completed Sydney Harbour Youth Hostel Australia (YHA), which was designed by Tzannes Architects and constructed by Built Pty Ltd.

Auswave Products Director Doug Matthews said creative thinking was required to provide a high quality access platform, matching steps and landings that would be totally accessible and easily maintained, blending the past and the present within a modern building project.

“This was achieved with the expert team at Paige Stainless and the outcome is a magnificent architectural solution,” Mr Matthews said.

Paige Stainless Director Kevin Finn said the ruins had previously been built over but, during the latest redevelopment, Sydney City Council felt it was important to save the heritage associated with the site.

Mr Finn said Paige Stainless supplied and fitted around 50 square metres of PAIGE STAINLESS HEELGUARD® flooring for the main entrance to the building, which lies about one metre above the cellar area of the original hotel.

Grade 304 stainless steel supplied by ASSDA Member Atlas Specialty Metals was used for the grillage due to its longevity in this inert environment, as well as its appearance.

“This was a very cool project to be involved in, not only because the new building is impressive in itself, but also because of the historic factors,” he said.

“Heelguard was used so that visitors could view the ruins through the grillage and also to enable natural light and ventilation to flow through to the ruins below.”

Mr Finn said safety was also an issue: the 5mm gaps between the grillage means that high heel shoes and toes can not get through and Australian Standards for slip resistance are exceeded.

The flooring is made of multiple panels that are fixed to a sub-frame designed by Paige Stainless. Each panel can be removed independently from the adjacent one if necessary, ensuring easy access if required.

ASSDA MEMBER CONTACTS
Paige Stainless
27 Cessna Drive
CABOOLTURE QLD 4510
Ph (07) 5499 1511
www.paigestainless.com.au

Atlas Specialty Metals
www.atlasmetals.com.au

nature provides inspiration

Working with stainless could only be described as a labour of love for retired engineer and designer Allen Minogue. After a 25 year career with ASSDA Accredited Townsend Group, Mr Minogue continues to work with stainless steel, creating larger than life sculptures from the material. His latest creation, The Jumping Barramundi, has been a year in production, stands 1.125m high and weighs 75kg.

Mr Minogue said he had spent quite a bit of time in Darwin and the Kimberley, which has inspired much of his work, including the dancing brolgas featured in Australian Stainless. “I look for ideas in nature and I couldn’t resist the lure of this iconic NT fish,” Mr Minogue said.

The sculpture features an internal stainless steel frame with a fibreglass body. Over 2000 scales were cut from .55mm thick grade 316 stainless steel, which were hand polished and screwed to the fibreglass body. The head, tail and fins were cast from 316 stainless, sandblasted and polished.

Mr Minogue works exclusively with stainless steel, which he sources from ASSDA Member Dalsteel Metals Pty Ltd.

CONTACT

Dalsteel Metals Pty Ltd
www.dalsteel.com.au

Townsend Group
www.townsendgroup.com.au

Allen Minogue
Ph 02 9528 9877
Email This email address is being protected from spambots. You need JavaScript enabled to view it.

stainless integral to design

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

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

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

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

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

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

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

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

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

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

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

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

CONTACTS

LWA Engineering
www.lwaengineering.com.au

Sandvik Australia
www.sandvik.com

Australian innovation

Marine applications of stainless steel have traditionally relied on the material’s corrosion resistance and strength. But when it comes to marine rescue vessels, safety is also a top priority.

Southport’s Volunteer Marine Rescue (VMR) is currently trialling an Australian innovation designed to enhance safety.

The Klein Architectural Grip (KAG) Rail, developed by ASSDA Accredited Fabricator Klein Architectural (Slacks Creek, Queensland), has permanent swages and ridges that fit the shape of a closed hand.

The ‘non-slip’ rail was originally designed for the industrial marine sector, where rails and workers’ hands are often wet and greasy, causing slippage on ladders.

In addition to the VMR, the rail is now being trialled on steep ladders at Wivenhoe Dam, Queensland and is suitable for use in a range of industries requiring a high level of safety, including mining, construction, heavy industrial, manufacturing, transport, oil and gas, power stations, and the aged care sector.

VMR Unit Training Co-ordinator Ken Gibbs said two Grade 316 rails were currently installed on their 8 metre Noosa Cat ‘Marine Rescue 2’ and had been tested in all types of weather conditions.

“We’ve got about 30 skippers who work in rotation and the feedback we’re getting is really positive,” Mr Gibbs said.

“The general consensus is that the rail offers superior holding capacity in both wet and dry conditions, without compromising strength.”

Mr Gibbs said during search and rescue operations, the weather was generally foul with water often taken over the bow of the vessel, making the hand rails slippery and testing both skipper and crew.

“Being able to fit our fingers into the ridges gives us a better grip and makes the operation much safer,” he said.

Klein Architectural Director Danny Klein said independent testing had shown the rail reduces handrail slippage by 80 per cent in comparison with regular stainless steel tube.

“The rail can also be fabricated in both left and right hand configurations, which would allow visually impaired people to identify in advance what a staircase is about to do,” Mr Klein said.

The KAG Rail is made to order and is available in a number of different stainless steel grades, depending on the application. The rails can be retro fitted or installed on new projects. Services such as water, electrical, air/gas and data can be hidden in the tube.

A patent is currently pending on the product, which complies with AS1428.1. Mr Klein said the Standard does not currently make particular reference to grip or slip, but the company was lobbying for this to be changed.

CONTACTS

Klein Architectural Pty Ltd
www.klein.net.au

Strength and corrosion resistance vital

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

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

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

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

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

• No bacterial traps
• Robust enough to withstand the harsh environment and repetitive shock loading
• Light enough to enable easy handling of the modules for cleaning
• Configured to enable easy dismantling for cleaning

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

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

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

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

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

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

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

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

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

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

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

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

The article featured in Australian Stainless Issue 47 - Spring 2010.

purge welding to minimise heat tint

Stainless steel is frequently specified for food production, pharmaceutical, chemical and industrial applications due to its corrosion resistance and cleanability. It is vital in these sorts of applications to avoid or remove the oxide heat tint or scale that forms when weld metal is melted, because this heat tint is non-protective and provides a place for bugs to settle or for corrosion to start in certain conditions. Purge welding is particularly useful in these circumstances if no post weld cleaning is possible, e.g. inside tubes.

What is heat tint?

Figure 1 (right) shows the typical heat tint formed on the welded side if stainless steel is welded without excluding oxygen. The thickest, darkest oxide is in the centre (where the metal was hottest for longest) and a similar double rainbow will form on the opposite, root side of the stainless steel.

However, if access is good, such as in a tank or large vessel, then the back of the weld can be protected by gas flowing through a backing bar or even by manually or automatically blanketing the weld root with an inert gas from a lance. Unfortunately, this is not practicable in small diameter tubes. Further, post weld cleaning of the surface may not be permitted in pharmaceutical or food industry tubing with highly polished surfaces.

How is heat tint minimised?

Purge welding is a method used to ensure that, with no post weld treatment, the root of TIG welds in tube or pipe has no more than a pale straw heat tint. This level of colouration is specified in AS/NZS 1554.6 and AWS D18.1/D18.1M:2009 (level 3) as the maximum permitted for tube to be used in the as-welded condition both for corrosion resistance and hygienic applications (see Figure 2 below).

The heat tint control is achieved by maintaining oxygen levels <50ppm (0.005%) while the metal is hotter than ~250^oC. It is assumed that weld preparation, heat input and weld technique are controlled to provide a full penetration weld with a smooth, cleanable profile suitable for Clean In Place (CIP) procedures.

Mechanical orbital TIG welding equipment should give the same result if the manufacturer’s instructions are followed. Modern orbital welders are relatively narrow and can weld close to an elbow, i.e. near the edge of the welding head, as shown by the offset distance in Figure 3 (right), which represents a side view of an elbow being welded. The orbital welder clamps around the pipe and, after purging, rotates automatically while TIG welding the join.

If a consumable is used it must be at least as corrosion resistant as the tube or pipe material. Otherwise, the narrow weld could corrode rapidly if the tube was used in a corrosive environment. Purge gas must be dry and is normally argon, although low oxygen nitrogen can be used (even for duplex tubing). However, if there is excessive leakage into the arc, then phase balances can be disturbed and cause either cracking, poor toughness or lower corrosion resistance.

For long lengths of tube or pipe it is common to use removable dams to contain the purge gas. There are two main types of dams illustrated in Figure 4 below:

• water soluble paper and adhesive tape inserted on either side of the weld area before assembly and flushed away afterwards; or

• rubber lipped dumbell shaped assemblies with one end of the assembly attached to a purge feedline and cable for removal after the weld has cooled. The other dam disc contains a vent to avoid pressurising the purged area. Inflatable bladders can also be used instead of the rubber seals.

Custom-made tapered foam discs with a rubber backing and a covering hat may also be used if externally welding a flange to a pipe.

Purge welding tips and tricks

Purge welding is a skill and it is important that the welder is qualified for the weld. It is also essential to assess if he/she is competent to weld on the day. The weld preparation must include verification that the longitudinal weld profile in the tube will permit a gas tight seal for purging.

When the dams are inserted into each section of the tube or pipe, the feed tube and extraction wire must not be tangled. The dam spacing must be large enough so they are not overheated but, typically, a couple of hundred millimetres is adequate. The weld area must be cleaned with a new wipe and volatile solvent, and then allowed to dry before checking the area is clean. The weld area must not be touched.

Align the matching faces and start the pre-purge. The flow should be turbulent enough to remove air from the surface of the pipe, i.e. ensure the stagnant, boundary layer is very thin. Venting must be sufficient to prevent pressurisation or reverse, swirling flow which will mix purge gas with the existing air and reduce the effectiveness of the pre-purge. Either monitor the exit purge gas with a meter (as shown in Figure 5, right) until the oxygen level is acceptable or purge until at least 10 times the dammed volume has flowed. If a significant root gap is required then it can be taped over during this purge. However, care is needed to avoid contaminating the clean weld preparation with the tape adhesive. After pre-purging, reduce the gas flow to avoid blowing out the weld and commence welding.

Plan the welding to minimise positional welding with its less controlled weld profile and heat input. If the ends are not well restrained by a jig, tack them (but ensure the tack is also gas shielded). Thicker wall materials may require a trailing shield to ensure air does not contact the external metal while it is hot enough to oxidise. This is not an issue if external mechanical cleaning is acceptable.

Summing up

Stainless steel’s unique characteristics make it the ideal material in many highly-sensitive applications, but it is vital that it is handled appropriately so it performs as required. Purge welding to avoid heat tint is one example where getting it right from the outset ensures corrosion resistance, cleanability and, ultimately, longevity.

Guidelines to Ensure Long Service Life

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

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

MIC

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

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

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

Hydrostatic testing practices to eliminate MIC

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

1. Fabrication practices

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

The likelihood of MIC will also be reduced by:

• Using full penetration welds; and
• Purge welding to prevent the formation of heat tint; or
• Removing heat tint by grinding or pickling.

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

2. Use clean water

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

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

3. Draining and drying

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

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

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

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

4. Chloride content and temperature

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

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

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

5. Standards

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

Conclusion

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

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

Stainless Technology Essential

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).

ICS 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.

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

Maximum impact two years on

Coloured stainless steel has helped revitalise what has become one of Victoria’s largest and most recognisable shopping precincts – Westfield Doncaster.

In late 2008 Westfield completed a major redevelopment and refurbishment of the Doncaster shopping centre (located 20 minutes east of Melbourne’s CBD), doubling the complex’s size.

Central to the centre’s new look and feel is the building’s ultra contemporary and striking cladded facade that features coloured and patterned stainless steel supplied by Steel Color Australia Pty Ltd.

Steel Color Australia owner Vince Araullo said more than 600 square metres of grade 304 stainless steel were used to construct the eye-catching “Red Wall”.

“The brief from the designers, Westfield Design and Construction, was to deliver a contemporary looking facade that not only provided the Doncaster shopping centre with plenty of colour but would also be hard wearing against Melbourne’s diverse weather conditions,” he said.

“Our coloured stainless steel, which we import from Italy and distribute exclusively in Australia and New Zealand, is manufactured by Europe’s leading specialist in coloured stainless steel and special metal finishes – Steel Color S.p.a.”

The stainless sheeting was fabricated and installed by Melbourne-based Barden-Steeldeck Industries. Manager and part-owner Michael Shacklock said this was the first time his company had worked with coloured stainless steel.

“By attaching the sheets to a sub-frame we were able to make certain that all 300 sheets of coloured stainless steel were accurately positioned to deliver the distinctive looking facade,” Mr Shacklock said.

Mr Araullo said the colour refraction from the Rosso (Italian for red) stainless steel provided a changing colour palette depending on the time of the day and viewing angle.

“The unique movement of colour across the stainless steel clad entrance is a major shift forward from traditionally sterile looking facades that appear on many shopping centres,” he said.

To avoid the potential reflectivity of the facade hindering nearby traffic safety, a Perla pattern was specified. The indentations of the pattern diffuse light and provide an optical flatness, which effectively eliminates reflections.

The pattern also provided improved strength, allowing for a lighter gauge of 1.2mm instead of, typically, 1.5mm or more.

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