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Safe Disposal with Simcraft Stainless Steel Products

As a general rule, the waste management method adopted for disposing of radioactive substances is critical. The main method of disposal is the dilution and dispersion of radioactive wastes using stainless steel equipment such as isotope flushing sinks

 

Last year, the University of Western Australia's School of Biomedical, Biomolecular and Chemical Sciences moved into the new $65M Molecular and Chemical Sciences building with state-of-the-art laboratories and equipment.

Generally, the materials used in biological sciences research work contain low radiotoxicity substances, however, full precautions are taken to ensure safe handling.

As part of the School of Biomedical, Biomolecular and Chemical Sciences upgrade, many of the laboratories were fitted with a number of isotope sinks and flushing isotope sinks fabricated by ASSDA Accredited Fabricator, Simcraft Products.

Isotope flushing sinks are designed to prevent splashing and to allow for the gradual flow of waste liquid into a stream of waters as it runs to waste.

Simcraft Products fabricates the sinks in 1.2mm grade 316 stainless steel with satin finish to the Australian Standard, AS2243.4.

Isotope flushing sinks feature an absolutely splash free flush action with a non-turbulent continuous curtain of water for a total surface wash and can also be custom built for hospitals, medical centres and laboratories.

This article featured in Australian Stainless magazine - Issue 35, Autumn 2006.

Manufacturing malt with stainless steel

Australians really enjoy a good beer - at home barbeques, parties, music concerts, sporting events - in fact, everywhere!

World beer consumption is increasing by more than two per cent a year, a trend that is set to continue. There is an important relationship with beer consumption and demand for its main and critical ingredient - malt.

Malting is the partial germination and kilning of a grain, usually barley. Malt gives varying colour, flavour and body to beer depending on the style of malt being used.

Australia is a key player in the world market representing about 32 per cent of world trade in malting barley and 12% of the world malt trade.

Joe White Maltings, an ABB Grain Ltd company, is Australia's largest malt producer with eight malting plants Australia-wide with a capacity to produce 500,000 tonnes annually.

An expansion at the company's Perth plant in May 2006 saw production capacity more than double from 90,000 tonnes to 200,000 tonnes.

ASSDA member, Stirlings Australia sourced more than 155 tonnes of grade 304 stainless steel 2B finish from ASSDA Major Sponsor, Outokumpu Stainless for the expansion. As the largest malting facility in the southern hemisphere, the Perth plant features stainless steel vessels throughout with cylindrico-conical steep vessels, circular germination vessels, a separate circular kiln, full automation and in-place cleaning.

ASSDA member, Stirlings Australia sourced more than 155 tonnes of grade 304 stainless steel with 2B finish from ASSDA Major Sponsor, Outokumpu Stainless for the expansion. Stirlings Australia also used its hi-definition plasma cutting service for processing of material ranging from 2mm to 20mm thick sheets by 1200,1500 and 2000mm wide plates.

The Perth-based global metals distributor also supplied more than $150,000 worth of stainless steel to Built Environs subcontractors for the fabrication of the project.

Press Construction Services were supplied with various grade 304 stainless steel pipe, plate, angle and flats including processing of all plate material for the fabrication of six steep vessels.

ASSDA member, Austline Fabrication of the Foodline Group of Companies was supplied various grade 304 stainless steel sheet, plate and angle for the fabrication of fan ducts and kiln hoods.

From this expansion, Joe White Maltings are able to meet increased demand from producers of most Australian beers and for the major brewers throughout Asia.

This article featured in Australian Stainless Issue 36, Winter 2006.

Gold Coast's Kirra Point: Looking Great Six Years On

When the Gold Coast City Council was seeking a stable and visually stunning medium for use on their Kirra Point board walk project in 1999, they looked no further than stainless steel and after six years in service, it still looks great.

 

Council engineers chose stainless steel for the upright posts and moveable handrail system for safety, corrosion resistance and aesthetic reasons.

When designing the project, the board walk had to take into account a steep vertical drop to the beach below - an important safety issue met by using stainless steel handrailing.

The board walk project was undertaken in two stages, the first of which involved constructing a concrete walkway and handrails along the Kirra Point foreshore. The second stage saw the construction of a timber board walk out over the foreshore onto the beach.

ASSDA Accredited Fabricator, Stoddart (Tom Stoddart Pty Ltd) supplied 186 custom made upright posts and supplied and installed 326 metres of stainless steel tubular handrails. Both were made from 316 grade stainless steel with a number 4 finish.

The upright posts were passivated in nitric acid after manufacture to ensure a clean surface and promote corrosion resistance.

The knowledge that ASSDA requires for its Accreditation Scheme was used in the execution of the structure, ensuring the ongoing satisfaction of the Council with minimal maintenance.

This article featured in Australian Stainless magazine - Issue 35, Autumn 2006.

Food Specification Improves Fabrication Practices

Hygiene and the 'cleanability' of equipment used in the production of food are paramount. The widespread use of stainless steel equipment in the food industry goes some way towards ensuring these criteria are met - but the assurances provided by stainless steel are only as good as the fabrication quality of the equipment.

Following a presentation at ASSDA’s annual conference in 2003 on the quality of food fabrications, particularly in the dairy industry, it became apparent that fabrication specifications, if they existed, were often inadequate and inconsistent.

As a result, ASSDA launched a co-operative venture, working closely with many fabricators involved in the food industry, to create the recently released "ASSDA Food Specification: Fabrication and Installation of Stainless Steel Process Plant and Equipment in the Food and Beverage Industries".

The title may be complex, but the intention is simple: used in conjunction with ASSDA's Accredited Fabricator Scheme, it will standardise fabrication practices in Australia and improve efficiency and reliability by raising the standard of quality delivered.

ASSDA's Food Spec is not intended to replace accepted national and international standards. Instead, it reflects their requirements in the design and fabrication process specifically for food and beverage plant. The specification is intended as a step forward from the more generic advice offered by the well-known "Blue Book", published ASSDA's sister organisation NZSSDA.

The Food Spec supplements the purchaser's specification and contract, with the purchaser's performance criteria and the supplier's design being the default conditions. There are prescriptive sections, such as those relating to spacing for access or acceptable levels of heat tint. However, best practice is flagged with the expectation that a contrary decision must be well supported. The consistent theme throughout is the delivery of cleanable surfaces in a hygienic environment.

The specification can be broken into four sections:

  1. Scope, definitions, interpretation, document hierarchy and suppliers systems required.
  2. Design requirements with both general rules and specific items for process equipment, process piping and other piping;
  3. Fabrication requirements for:
    • overall necessities of grade, materials care, welding and finishing procedures;
    • process vessel fabrication, whether by the supplier or others;
    • the handling, welding and finishing of process tubing at ambient or elevated pressure; and
    • the fabrication of non-product contact pipework at low or high pressures.
  4. Practicalities such as transport, installation, commissioning and insurance.

The specification includes two appendices that list relevant standards and a discussion on the pros and cons of autogenous and filler metal sue in welding of tubing.

There is no doubt that ASSDA's Food Specification fills a void in the food industry. It is now up to operators in the industry to use it to improve practices in both their own businesses and the industry as a whole.

Copies of the specification are available from the ASSDA office on (07) 3220 0722. Details of the complementary Accredited Fabricator Scheme are available from www.assda.asn.au

This articles was written bu ASSDA's technical advisor, Graham Sussex.

The ASSDA Food Specification has drawn on the work of many operators in the industry and their assistance in time and documents is gratefully acknowledged.

This article featured in Australian Stainless magazine - Issue 37, Spring 2006.

No 4: the workhorse finish

No 4 finish stainless steel is the workhorse of the light fabrication industry. The easiest of the finishes to maintain, No 4 finish is used for work surfaces, handrails and where appearance is important.

A 'No 4' surface is produced by cutting the surface with abrasive belts to remove a very small amount of metal without affecting its thickness.

For architects and designers, No 4 finish gives low gloss and best apparent flatness of panels.  For fabricators, the No 4 finish is directional, allowing easy matching of surfaces and refinishing of welds. For end users, the surface can be repaired to remove any service damage.

No 4 finish is duller than the other common finishes, 2B and BA and is generally used where lower reflectivity or gloss is required and where welds and other fabrication marks are to be refinished to match the original surface. This is not possible with 2B and difficult with BA.

Abrasive belts have very fine grains of refractory material such as silica, alumina and zirconia embedded in an adhesive layer on a flexible cloth or paper backing. The belts are wider than the stainless steel, which is usually worked on as coil, or sometimes in individual sheets. The steel is run slowly under rolls, on which the abrasive belts run.

The polishing machines at stainless steel mills lubricate the cutting action by flooding the strip with oil. This helps to keep it cool, and gives a finer, more uniform surface.

The variability of the process means not every No 4 finish looks the same, even from the same source. Different manufacturers use belts with different combinations of grit sizes, and the finish can vary through the life of a set of belts.

Where it is important that the appearance of material matches on a job, it should all be taken from the same pack of sheets, used sequentially and in the same orientation. A reasonable match in appearance can be achieved more readily with No 4 finish than with 2B or BA mill finishes.

No-4-finish.jpg The Owner of this resource has not specified a description BA-finish.jpg
No 4 Finish 2B Finish BA Finish

Standards

Until recently, standards defined No 4 finish in terms of the coarseness of the abrasives used to produce a general purpose finish widely used for restaurant equipment, kitchen equipment, shopfronts and food processing. New editions of the American and European standards define limits of surface roughness achieved.

Finishes produced by use of abrasives may be called ground or polished or abraded or linished. These words describe a process and do not specify the end result.

ASTM A480 defines No 4 finish simply as, “General purpose polished finish, one or both sides”. It also states, “No. 4 - A linearly textured finish that may be produced by either mechanical polishing or rolling. Average surface roughness (Ra) may generally be up to 25 micro-inches (0.64 micrometres). A skilled operator can generally blend this finish.”

The practice in Australia is only to use 'No 4' as a description of a polished finish and it is not a rolled finish. The European standard, EN10088-2, defines two finishes, '2J' and '2K'. There is no prescription of the appearance or roughness of the '2J' finish, but '2K' is defined as surface Ra below 0.5 micrometres. The notes state, ”Additional specific requirements to a 'J'-type finish, to achieve adequate corrosion resistance for marine and external architectural applications.”

Figure 1: No-4-finish-graph.jpg Figure 2: 2B-finish-graph.jpg
Figure 1: Surface trace of a typical No 4 finish
(Ra = 0.41 micrometres)
Figure 2: Surface trace of a typical 2B finish
(Ra = 0.20 micrometres)

The surface traces of Figure 1 and Figure 2 show comparisons between typical No 4 and 2B finishes. Unlike a 2B finish which is generally rougher on thicker coil, the roughness of No 4 does not vary with the steel thickness.

While Ra can be specified to give better control of the corrosion properties of the surface, it correlates only moderately with appearance and is also difficult to measure reproducibly.

Gloss is the amount of light reflected whether specular (mirror like) or diffuse. It is moderately correlated with appearance and with surface roughness, but can also have problems when used for specification.

Neither Ra nor gloss are suitable for specification for critical jobs in architecture. Two finishes with the same Ra can look substantially different, as can finishes with the same gloss level.

For critical jobs appearance is best specified using reference samples viewed under agreed conditions. These should be large enough that they can be viewed from a variety of angles and distances - appearance can vary with viewing angle.

Corrosion Resistance

The corrosion resistance of a No 4 finish is usually lower than that of a mill finish (BA or 2B) on the same grade.

The surface scratches or grooves produced by abrasion expose sulphide inclusions, which are always present in all steels, and can act as a catalyst for corrosion.

The passive surface layer is more likely to be disrupted somewhere on the vastly increased surface area with all its sharp peaks and deep valleys. It is difficult to keep the surface clean when there are intersecting valleys, torn metal flaps or peaks that have been folded over.

Corrosion resistance may be reduced depending on the stainless steel grade used. By using grade 316 with a No 4 finish in aggressive environments, the corrosion resistance is negated and may be less than on 304 with a 2B or BA finish.

Figure 3: The accceleration of the corrosion of the surface at Ra above 0.5 micrometres is apparent.
Figure 3: The acceleration of the corrosion of the surface at Ra above 0.5 micrometres is apparent.

Figure 3 shows the results of electrochemical tests for corrosion of a polished surface. Corrosion resistance of a smooth surface can be better than the corrosion resistance of an abraded surface of a more highly alloyed grade.

The orientation of the No 4 finish is also important. When the lines on the surface are vertical, drainage is easier and corrosion resistance is better than when the lines are horizontal.

The reduced corrosion resistance of the No 4 finish is not likely to be of concern in mild applications such as food preparation and display. However, in more aggressive conditions such as marine and industrial atmospheres it is important to be aware of the reduced corrosion resistance of No 4 finish and to take steps to improve the resistance.

Corrosion resistance of No 4 finish can be improved by pickling the surface in a mixture of hydrofluoric and nitric acids, or passivating in a nitric acid solution.

The passivation treatment dissolves the sulphide inclusions in the surface, but doesn't change the appearance of the surface. The pickling treatment is more aggressive and removes both the sulphide inclusions and some of the rougher parts of the surface, dulling the appearance.

Unfortunately it is almost impossible to achieve a uniform finish, and it is rarely practical to pickle for better corrosion resistance. Passivation is often used. ASTM A967 “Chemical Passivation Treatments for Stainless Steel Parts” specifies a number of treatments with various acid strengths, temperature and contact time.

Electropolishing the surface can also improve the corrosion resistance and brighten the surface. The peaks on the surface are smoothed, reducing the Ra value and increasing the reflectivity or gloss. The sulphide inclusions may also be removed or reduced.

Protection of the Surface

No 4 finish is usually supplied with a protective plastic film of white polyethylene, which often has printed lines on the plastic in the same direction as the No 4 polish.

It is best to keep the film on the surface of the steel during fabrication, to prevent handling and transport damage. The film has limited resistance to sunlight, and should not be left on the steel in the sun for more than a week or two - an hour or two if the film isn't black underneath. The film may bake onto the surface and either become brittle or tear into strips on removal, or leave the glue on the steel surface.

Glue on the steel will trap dirt, and may cause rapid surface discolouration or tea staining.  If it is suspected there is residual glue on the steel, swab the surface with a solvent such as Methyl ethyl ketone (or MEK - a solvent) available from panel beaters suppliers. You may need to test other solvents, depending on how the glue has polymerised.

The water break test tells you the surface is clean - clean water dries as a film, doesn't stand in bubbles on the surface. A final wipe with a glass or window cleaner will ensure a streak free finish.

Cleaning

No 4 finish can usually be kept clean by wiping down with a damp soft clean cloth. For grease, moisten the soft cloth with ammonia solution, or with one of the household liquid grease removers. Very hot water is also quite effective.

Wiping should always be in the direction of the polishing lines. Some No 4 finishes can pull threads and fluff from the cloth which are very hard to get off the steel.

Abrasive cleaners and materials such as Scotchbrite™ should never be used as these will change the appearance of the surface. If you want to change it, try an inconspicuous area, then treat the whole surface - but it's difficult to get it uniform.

There are also white powder stainless steel cleaners (Clark and Esteele), made of sulphamic acid, which can be wiped over the surface on a damp rag to brighten it - test an inconspicuous area first. Fingerprints can be made less obvious by applying a light oil to the surface. There are many proprietary products available, usually labelled 'stainless steel cleaner'. Choose an oily one, although it will tend to trap dust.

This ASSDA technical article was written by Dr Alex Gouch, Development and Technical Manager of Austral Wright Metals. ASSDA acknowledges the assistance and contribution of Mr Peter Moore, Technical Services Manager of Atlas Steels and Dr Graham Sussex, ASSDA Technical Specialist in the production of this article.

This article featured in Australian Stainless Issue 36, Winter 2006.

Stainless steel 'Travellers' mark journey of migration
Telling the tale of migration to Victoria is 'The Travellers', a series of giant stainless steel sculptures sliding quietly across the Sandridge Rail Bridge on Melbourne's Yarra River.

Stainless Steel 'Travellers' Mark Journey of MigrationUnveiled just three days from the start of the Melbourne 2006 Commonwealth Games, the 10 sculptures are a tribute to multiculturalism.

Each of 'The Travellers' figures represents a period from our Indigenous and immigrant histories (as defined by historian Dr James Jupp) and were designed by Lebanese Artist, Nadim Karam of Atelier Hapsitus.

'Gayip - The Aboriginal Period', the first sculpture, is stationed permanently on the river bank to depict the Indigenous owners of the area who were here already.

Nine of the 10 sculptures cross the river three times a day on a fixed bogie system to represent stages of migration in Australia's history from the convict and gold rush periods through to European and refugee settlement.

More than 3.7 km of stainless steel (in 4455 pieces) was used to create the sculptures.

ASSDA member, Silverstone Engineering fabricated the majority of the 10 sculptures from grade 316 stainless steel supplied by ASSDA Major Sponsors, Sandvik Australia Pty Ltd, Atlas Steels and ASSDA Member, Midway Metals Pty Ltd.

Each of 'The Travellers' figures represents a period fro ou Indigenous and immigrant histories.The remaining stainless steel sculptures were fabricated by Danfab, JW Metal and Able Engineering.

Stainless steel rectangular hollow sections were used on the outer frames. The inner rails were made of pipe and bar. Some of these rectangular hollow sections were inductarolled (rolled after heating by using an induction furnace) by Melbourne company, Inductabend, with a discoloured zone or heat band running around the material.

The sculptures required much tighter radii than had previously been delivered, and Inductabend's equipment was pushed to its limits when bending the steel sections.

Following fabrication, the sculptures were then polished to 0.4 Ra, cleaned and then passivated to ensure high corrosion resistance.

Originally built in 1888 by David Munro, the Sandridge Bridge is considered one of the earliest examples of steel girder bridge construction in Australia.

The $3 million 'Travellers' sculptures project was part of an $18.5 million Sandridge Bridge Precinct development funded by the City of Melbourne and the State Government that includes a new pedestrian bridge, a plaza and a youth precinct on the north bank.

This article featured in Australian Stainless Issue 36, Winter 2006.

Quality Fabrication Keeps the Meat Rolling

Loss in production due to installation of new equipment is always undesirable, which is why an upgrade on the scale of Australia Meat Holdings’ recent boning room expansion at Aubigny (west of Toowoomba, Qld) was even more remarkable.

 

The project, managed by Wiley & Co, more than doubled the size of AMH’s existing boning room, improved work place ergonomics and provided for future growth – all without interruption to production.

The expansion incorporated more than $4 million worth or 100 tonnes of stainless steel, around half of which was fabricated by ASSDA Accredited Fabricator G & B Stainless from Crestmead, Qld.

G & B Stainless director John van Koeverden said their company’s work on the project involved 20 to 30 people in their workshop and eight people on site for around 5 months.

The company fabricated and installed the majority of conveyor equipment, including the product conveyors, empty carton conveyors and packed carton conveyors.

Mr van Koeverden said mainly 304 and some 316 stainless was used for the double and triple tier conveyors.

“One of the unique features of the job was the two 60 metre long boning conveyors and integral slicing tables, which we designed specifically for this application,” he said.

“The tables incorporate over 100 stations and feature pneumatic lifts to raise the tables up to 90 degrees for ease of cleaning.”

G & B Stainless used a glass bead blast finish over most of the stainless steel, primarily to remove weld stain and further enhance the hygiene features of stainless steel.

Wiley & Co project engineer Scott Hebbard said the fact that G & B Stainless was ASSDA Accredited played a role in their selection to fabricate the majority of the stainless steel equipment in the new boning room.

Four other fabricators shared the remainder of the work, including the fully enclosed walkways and the conveyors up to and taking away from the vacuum packing equipment.

This article featured in Australian Stainless magazine - Issue 37, Spring 2006.

Stainless rebar enhances technology performance

Stainless steel's non-magnetic properties were an important factor in the design, building and construction of the University of New South Wales' (UNSW) new Analytical Centre.

The facility has been designed to enhance the performance of high-tech analytical equipment such as the UNSW's nuclear magnetic resonance instruments (NMRs).

The centre is one of six components in the North Mall Development Zone (NMDZ) project, located within the Kensington Campus of the University of New South Wales (UNSW).

According to Mr Ed Smith of McLachlan Lister, the Project Directors of the NMDZ, building will accommodate both staff and equipment from the University's existing Electron Microscopy Unit (EMU), Nuclear Magnetic Resonance (NMR) and centre and eight other technical scientific instrument centres.

“The five NMRs within the Analytical Centre will emit very strong electromagnetic fields. A standard ferrous concrete reinforcement would adversely effect these fields and consequently the performance of these machines”.

ASSDA member, Ancon Building Products supplied 150 tonnes of 304 and 316 grade stainless steel ribbed reinforcement bar for the concrete slabs, beams, piles and columns.

Both 304 and 316 stainless steel are non-magnetic and strong enough to replace carbon steel reinforcement bar in the design.

Some stainless steel pile cages were passivated after welding. Ancon Building Products cut and bent all bars to schedule, longer bars were created using stainless mechanical couplers, which were custom fabricated.

This article featured in Australian Stainless Issue 36, Winter 2006.

445M2: A New Generation Stainless Steel (Part 1)

This article is the first in a series showcasing the uses of 445M2 stainless steel. Read Part 2. Read Part 3.

Australians' love of the water has always provided challenges to the construction industry, particularly when it comes to choosing materials that can be used in aggressive environments such as near the coast or swimming pools.

Stainless steel grades 316 and 304 have long been the obvious solution in these applications, but the key factors of formability, cost and corrosion resistance are now shining the spotlight on an alternative grade.

445M2 stainless steel has been used in Australia for a number of years for roofing and walling applications, and its characteristics are now proving useful for a broader range of applications.

The material, supplied by ASSDA member Austral Wright Metals, is being used by Dunning Engineering Services Pty Ltd for a range of stainless steel pergola brackets.

Dunnings - a South Australian based manufacturer of builders and plumbers hardware, who also operate a sheet metal pressing and fabrication facility - developed the range in response to the growing demand for better corrosion-resistant products that can be used in aggressive environments.

The company experimented with punching and bending various grades of stainless steel, including 316, but it was 445M2's formability that provided the crisp, clean angles they were seeking, with the advantage of reduced tool wear.æ Dunnings was also able to fabricate with existing tooling and machinery, avoiding the prohibitive cost of new dies and tooling.

More importantly, 445M2 is a marine grade stainless steel with the corrosion resistance of 316 or better and a cost that falls between 304 and 316.

Dunning spokesperson John Gill said 445M2 resisted the salt from the surf, and gave safe performance over a long life - even when painted.

"Due to the formability of 445M2, the savings to our business have been enormous and we are now looking at other areas where 445M2 could be applied."

This article featured in Australian Stainless magazine - Issue 37, Spring 2006.

Design Software Vs Back to Basics

New technology to assist with accurate design is always welcome, but it is important that users proceed with caution when using international design tools.

There is no doubt that designing with stainless steel offers endless opportunities for architects and engineers to be both creative and functional. At the same time, it is critical that the design is right for the application.

 

Thanks to the internationally-recognised research of an Australian expert, as well as some design software now available free online, getting the design right for stainless steel structures has never been easier. However, as outlined below, it is more important than ever for design engineers to use caution when using international technology.

History of Design in Australia
The Australian Standard for design of stainless steel structures, AS/NZS 4673:2001 “Cold-formed stainless steel structures” was first published in 2001 and provides methods for design calculations. Applicable to cold-formed structures, including construction with tubular hollow sections, it provides a means of designing light and innovative structural solutions.

Traditionally, design engineers have reached for ‘load tables’ – or, strictly, Member Capacity Tables. Most design offices have tables with the results of calculations for various steel sections and loading regimes, generally published by suppliers of carbon steel.

But carbon steel has different properties from stainless steel, so these tables are not right for stainless steel – they may be too conservative or not conservative enough.

Another problem is that some engineers have assumed because they can find a section in carbon steel load tables, they can source it in stainless steel – only to discover they can’t, after doing an expensive design.

Designing with Software
Load tables for stainless steel are available from the Steel Construction Institute in the UK. The SCI is an independent, technical, member-based organisation with over 850 corporate members in 40 countries around the world.

Now the SCI has made available free software for design calculations for stainless steel members, using the methods of the European Design Manual, published by Euro-Inox.

Available over the web at http://www.steel-stainless.org/software/, the software speeds structural design calculations for a range of sections and stainless steel grades.

However, a word of warning: the software uses methods in compliance with parts of Eurocode 3 “Design of steel structures”. The Australian code for design of stainless steel structures, AS/NZS 4673:2001, follows the methods of the USA code, not the Eurocode. This is logical, as the Australian codes for the design of cold-formed carbon steel structures are also aligned with the USA codes and the trend in the Australian construction industry is to employ cold-formed steel to achieve lightness, material efficiency and enhanced strength.

So the SCI software must be used with some caution – it is the best available, but not ideal. The software should not be used in conjunction with the Australian code AS/NZS 4673:2001, as mixing clauses of different specifications is not an acceptable practice. This caution applies particularly to the design of welded structural members, which is catered for by the SCI software but not within the scope of the Australian Standard.

Future Improvements
In January 2005, Professor Kim Rasmussen of Sydney University was appointed chairman of the American Society of Civil Engineers (ASCE) Standards Committee responsible for the American “Specification for the design of cold-formed stainless steel structural members”. This is the Standard that formed the basis of AS/NZS 4673:2001.

The ASCE Standards Committee will be updating the American Standard and Professor Rasmussen will present the new rules implemented in AZ/NZS4673 to the American committee, together with design recommendations derived from recent and ongoing research at Sydney University.

The ASCE Committee is expected to adopt the new rules and recommendations. Subsequently, there is likely to be an update to AZ/NZS 4673 – so there is an ongoing cycle of improvement, helped along by the world-class research in stainless steel structures undertaken by Professor Rasmussen and his students at the University of Sydney.

What Does it all Mean?
In short, international design tools such as the free software available from the SCI can provide some assistance in getting the design right for stainless steel structures, but they don’t provide all the answers and can even complicate matters. Sometimes good design means getting back to basics.

This ASSDA technical article was written by Dr Alex Gouch, Development and Technical Manager of Austral Wright Metals.

ASSDA acknowledges the assistance and contribution of Professor Kim Rasmussen from the School of Civil and Mining Engineering, University of Sydney.

This article featured in Australian Stainless magazine - Issue 37, Spring 2006.

 

Big Fish Swimming in a Small Pond

Northern Territorians know their barramundi, which is why ASSDA Accredited Fabricator Northern Stainless had to get it absolutely right when they reeled in the contract to design and fabricate this 1030mm specimen.

The silver fish has a mythical reputation in the NT, not least because of its shimmering, silver appearance.

Northern Stainless operations manager Darren Colbert said they had no hesitation in saying they could get the job done to their client's satisfaction, because of their ability to create the barra's mesmerising shimmer in stainless steel.

We knew stainless was the right material for the job because we needed the water feature to last in Darwin's tropical environment, as well as best represent the barra's colour, Mr Colbert said.

We promised the client that we would create something that everyone would want to steal and I reckon we delivered.

The fish, which was commissioned for Osborne Family Holdings Hastings over Mindil apartment complex in Fannie Bay, Darwin, was fabricated from around 15kg of 316 stainless steel with a No. 4 finish. It was then regrained and the scales were polished into it. A 6mm tube sits inside, enabling the water to spray the gill plate.

Mr Colbert said one of the challenges of the project was converting a graphic design program to create a laser file.

The barra was cut out flat with a laser, then rolled and hand curved to create the three dimensional sculpture.

When it is installed in situ (expected to be late October 2006), there will be a fishing rod mounted on the wall of the water feature, with an optic fibre fishing line threaded with a stainless steel fly hook. The entire sculpture will rock slightly, creating turbulence in the water and giving the impression that the barra is working hard against being reeled in.

This barra may not enjoy the freedom of the NT's waters, but it will certainly garner the same admiration as the real thing.

This article featured in Australian Stainless magazine - Issue 37, October 2006.

Mrs Crocket's Stainless Kitchen

Twelve months after the design and installation of a unique cabbage processing system in Melbourne, the importance of quality stainless steel fabrication has never been clearer.

 

ASSDA Accredited fabricator Bridgeman Stainless Solutions (Brendale, Queensland) was commissioned to design the unique facility at Mrs Crocket's Kitchens, which was completed in October 2005.

The $500,000 project incorporated various plate, sheet, pipe and RHS stainless in grades 304 and 316, and was specified to reduce the risk of contamination in the handling processes for all coleslaws, pastas and food products.

Bridgeman's Managing Director Len Webb said there was previously no system available to perform the process that Crocket's required.

"We engineered and designed the equipment with input from the Crocket's engineer. Always at the forefront of our minds was that the prevention of food contamination is paramount in commercial food preparation areas."

The design of the cabbage line was significant and a huge improvement to the current system set up at the head office site in Queensland. The new design incorporated all processes: tipping, coring, washing, dicing, hopper and outfeed, all in a compact line that now has significantly less labour attributed to it.

The stainless itself was rolled, formed, bent, welded, sanded and polished to meet food grade requirements. Mrs Crocket's Kitchens Maintenance Manager Mark McGauley says stainless was specified because it is easy to clean and maintain.

"We know that the contact area and machinery is clean so this ensures any piece of food that comes into contact with these areas is safe."

This article featured in Australian Stainless magazine - Issue 38, Summer 2006.

445M2: A New Generation Stainless Steel (Part 2)

This article is the second in a series showcasing the uses of 445M2 stainless steel. Read Part 1. Read Part 3.

The use of stainless steel plant and equipment in the food industry continues to prove its worth as an increasing number of processors adopt its use in line with the dedication and obligation to food quality and safety.

Whilst stainless steel grades 316 and 304 offer an environment of easy maintenance and cleaning, 445M2 stainless steel goes one step further.

445M2 panels have been supplied to Bertocchi Smallgoods by ASSDA Major Sponsor Austral Wright Metals, following a four-month trial of all three grades of stainless steel.

Bertocchi, a Melbourne-based company producing hams, bacon, salamis and other specialised continental smallgoods, sought an alternative to their existing painted steel linings after they discovered the life of the linings was too short for their high cleaning standards.

The walls and ceiling of the factory are regularly cleaned in line with a guarantee of the highest quality health and safety standards, together with absolute traceability of every unit of product.

This is where stainless steel stepped in.  The hardness and smoothness of stainless steel enables it to resist the adhesion of soils and bio-films, and the excellent corrosion resistance allows it to be easily cleaned and sanitised. Indeed, laboratory tests prove stainless steel is significantly more hygienic than other materials, even when used for food contact surfaces. Moreover, the taste and colour of food products are not affected by stainless steels.

After four months of trialing panels of stainless steel grades 304, 316 and 445M2, Bertocchi Smallgoods chose the new generation ferritic grade 445M2 to line the factory – ceilings and walls. With superior corrosion resistance to grade 316, 445M2 resists the powerful cleaning agents used to keep the factory clean, as well as the hot, humid and salty atmosphere around the brine lines.

So far, Bertocchi has installed 10 tonnes of 445M2 0.7 x 1219 mm sheet with a 2B finish.  The result?  A clean, bright factory that’s easy to keep that way.  And Bertocchi intends to keep going until the entire factory is lined with 445M2.

This article featured in Australian Stainless magazine - Issue 38, Summer 2006.

Smooth and Corrosion Resistant Surfaces from the Mill

This article is the second in a series on common finishes. The first (Winter edition 2006) dealt with the abraded 'No. 4' (2K, 2J) finish. This article looks at 2D, 2B and BA: smooth and corrosion resistant surfaces produced at the steel mill. Subsequent articles in this series will cover mirror polished (No. 8 or 2P) and profiled and hot rolled (No. 1) finishes.

What are Cold Rolled Finishes?
Cold rolled finishes apply to flat products such as sheet or coil, with thickness less than about 5mm and usually less than 3mm.  They are firstly hot rolled into a strip (or cast into a slab which is hot rolled into a strip) and then cold rolled. Cold rolling reduces the thickness by at least 50%.  This smooths the surface, refines the grain structure and causes differences in the mechanical properties along and across the rolling direction.  In the case of austenitic and duplex alloys, the process hardens and strengthens the stainless steel.  Finally, the steel is softened by annealing in a furnace.  Each surface finish may undergo additional processes to improve the surface further.  The smoother the surface finish is, the higher resistance to corrosion it will be.

These mill produced finishes must be handled carefully as surface damage such as scratches, grinding marks or spatter cannot be matched by polishing with abrasives or etching with chemicals.  Of the 3 finishes, BA is most nearly able to be matched by a mirror polish.

Standards
The most common definitions of these surface finishes are provided by ASTM A480 and EN 10088. In both cases it is the cold rolled manufacturing method that is specified rather than specific, measurable characteristics about the surface. We have used ASTM A480 as an example:

ASTM A480:
No. 2D – A smooth, non-reflective cold-rolled annealed and pickled or descaled finish. This non-directional finish is favourable for the retention of lubricants in deep drawing applications.

No. 2B – A smooth, moderately reflective cold-rolled annealed and pickled or descaled finish typically produced by imparting a final light cold-rolled pass using [large diameter] polished rolls. This general-purpose finish is more readily polished than No 1 or 2D finishes. Product with 2B finish is normally supplied in the annealed plus lightly cold-rolled condition unless a tensile-rolled [harder and stronger] product is specified.

Bright Annealed [BA] Finish – A smooth, bright, reflective finish typically produced by cold rolling followed by annealing in a protective atmosphere so as to prevent oxidation and scaling during annealing.

2B
2B is the most widely used stainless steel surface finish. It is especially common in industrial, chemical and food processing applications such as process vessels and tanks. It is also used in some architectural applications that will not be closely examined for uniformity of finish such as downpipes and gutters.

When specifying this finish think about these attributes:

- 2B is the most economical finish
- it is highly corrosion resistant because it has been chemically pickled and is smooth
- over broad areas and between batches, etc it is not uniform and may not match in appearance
- it has been produced in the mill and can’t be   matched after fabrication- it is often protected by plastic films until final cleanup and commissioning

2D
2D is used around the world in applications where its low reflectivity is important. The largest application is in roofing materials. The surface is rougher than 2B and retains lubricants better making it appealing for deep drawering. 2D surfaces are not designed for appearance so the limitations on matching of weld and other surface damage is not as critical.  Railcars are a typical example where thicker sheet and ongoing abrasive damage make the rougher 2D a suitable finish.

When specifying this finish think about these attributes:

- 2D is not commonly available in Australia
- it is highly corrosion resistant because it has been chemically pickled and is relatively smooth
- over broad areas and between batches, etc it is not uniform and may not match
- it has been produced in the mill and can’t be matched after fabrication

Bright Annealed (BA)
The classic use of a BA finish is domestic: the interior of a dishwasher or clothes washing machine. In the clothes washer, it also provides a smooth, non-abrasive surface for the clothes to slide around.  The mirror like surface is also used in road mirrors where a precise image is not required.

When specifying this finish think about these attributes:

- BA is common in some grades and thicknesses, but not all
- it is highly corrosion resistant because it is very smooth
- different batches may not match
- it has been produced in the mill and can’t be exactly matched after fabrication although a mechanical mirror polish can be close.

Post Production Processing to Improve Corrosion Resistance
All the cold rolled processes include a pickling stage. Pickling is the removal of high temperature scale and the adjacent low chromium layer of metal from the surface of stainless steel by chemical means. Pickling will also remove manganese sulphide inclusions and any other contamination on the surface. Pickling results in a very clean, highly corrosion resistant surface, but will slightly roughen the surface.

Pickling any of these finishes will cause a matt or etched rougher area, most apparent on the BA surface and least on the 2D.

Differences Between Alloys
Most articles on finishes assume that standard grade austenitic stainless steel is used.  Typically a highly corrosion resistant grade has a duller appearance than the same thickness material with a lower corrosion resistance.  This illustrates the more aggressive measures required to remove oxide scale from a high alloy austenitic or duplex than a standard grade 304 or 316.

There is little data on finishes of ferritic grades but general observation shows that for comparable thickness and finishing processes, cold rolled 430 is brighter than 304. It is not known if this difference extends to comparisons between more highly alloyed grades.

This article featured in Australian Stainless magazine - Issue 38, Summer 2006.

Stainless Steel Launches its Artistic Merit

Internationally renowned, Yackandandah based sculptor Benjamin Gilbert was commissioned to create a series of sculptures for Melbourne’s Commonwealth Games.  Extending six metres in the air, the exhibits laid testament to three different stages of a pole–volter whilst displaying the versatility and artistic merit of stainless steel.

Benjamin used grade 304 stainless steel, supplied by ASSDA major sponsor Atlas Specialty Metals in Wadanga.  He has worked with stainless steel for 10 years and believes it is cost effective and cheaper to use than other materials. Also, the added ability of using off cuts in his work suited Benjamin’s ‘green’ focus.

“As a practising environmentalist, there are some good arguments for using stainless steel,” Benjamin says.

Indeed, stainless steel is one of the most recycled metals in the world and, according to the International Stainless Steel Forum, any given stainless steel object has an average recycled content of about 60%.  Benjamin also says the fact that stainless steel doesn’t need to be finished (ie painted) makes it an attractive material.

“For what you pay extra in materials, you don’t need to spend on additives.”

Using a sculpting technique taught to him during his time in Estonia, Benjamin has successfully adapted it for use with stainless steel.

The sculptures used up to 100kg of stainless steel – 1mm sheet, 5mm rod and a 25mm square tube substructure underwater.  With the ability to flex in the wind, the 35mm poles are re-enforced with inner tube to build up spring, similar to a leaf spring on a trailer suspension.

Benjamin enjoys ‘non-trade’ related thinking with his designs and, although he admits to having difficulty sourcing tools in Australia, he says the lighter, thinner materials are easy to use when spot welding and give greater flexibility when using metal shears.

During his work, Benjamin used a thin disk on a 5” grinder and a stainless steel wire wheel to ‘texturise’ the surface.  He believes there is “a lot more that can be done with finishes”, particularly by hand.

Other projects Benjamin has worked on, incorporating the use of stainless steel,  include a life size work of the Ned Kelly Gang (at Beechworth) and a bigger public artwork for the Camden Museum and Library redevelopment in South Sydney.  Once completed, in late January, a 16 metre grapevine in stainless steel will be exhibited, in recognition of the first grapevine in Australia.

Photograph by Rob Lacey Photography, Wodanga.

This article featured in Australian Stainless magazine - Issue 38, Summer 2006.

A Great Aussie Tradition Makes its Way

For those who love to indulge in a life of sun, surf and sand the idea of placing a barbeque in such rust-promising environments is not often an option as their longevity is compromised.

But Gold Coast company Southern Stainless has bridged the gap between a nautical lifestyle and the great Aussie tradition by manufacturing barbeques in stainless steel.

ASSDA member Southern Stainless typically specialises in the manufacture of stainless steel products including wine storage and fermentation tanks and marine fitouts, but supplying stainless steel barbeques, boat mounting systems and accessories to the general public, wholesalers, retailers and building industry has proven to be one of their fastest growth areas.

The barbeques are made from 316  grade stainless steel, with a  2205 duplex grade stainless steel plate, which is more corrosion resistant and easier to clean.

The barbeques are fully welded to enhance strength and use an electropolished finish to aid in corrosion resistance and provide a durable surface.

Southern Stainless Managing Director Phillip Brown says the barbeques can be designed to suit customer requirements and are 100% Australian owned and made.

“Chinese manufacturers retail theirs slighty under our price,” Phillip says.  “A certain percentage of the market will always go for the cheaper alternative, but when consumers are looking for quality, they tend to stick with locally-made products.”

This article featured in Australian Stainless magazine - Issue 38, Summer 2006.

445M2: A New Generation Stainless Steel (Part 3)

This article is the third is a series showcasing the uses of 445M2 Stainless Steel. Read Part 1. Read Part 2.

The Applied Science Building at the University of NSW is a landmark in the Eastern suburbs of Sydney. This world-class multi-storey complex of research laboratories and lecture theatres has recently been extended and upgraded, including the air-conditioning and fume extraction systems.

The new air conditioning and ventilation systems were placed on the roof. Management at the University were concerned that the upgrade would be a major disruption and not one they wished to endure more than once in a generation. They needed materials to be long-lasting and require minimal maintenance.

As contractors on the project, Croydon industries chose a new generation marine grade stainless steel. 445M2 was selected for the ducts of the roof, which were exposed to a marine atmosphere created by surf at Maroubra Beach just a few kilometres away.

Brian Clark at Croydon Industries says, "This was the first time we used 445M2, and we were a bit apprehensive - but it gave us no problems. It formed very easily, producing clean lines and well shaped panels with no flaws.

"The stream diffuser sheet of perforated metal was a dream to make.

"The punching ran cool, they sheet came out flat, with very little burr and at a lower cost than the familiar 316. We're glad we opted to use 445M2, it's been a win-win for all."

This article featured in Australian Stainless magazine - Issue 39, Autumn 2007.

Smooth and Corrosion Resistant Surfaces from the Mill

This article is the final in a series on common finishes. Previous articles in this series dealt with the workhorse No. 4 (2J/2K) (AS36, Winter 2006) and the mill finishes 2R (BA), 2B and 2D (AS38, Summer 2006). This article looks at mirror, profiled and coloured surfaces.

Mirror polished surfaces, as the name implies, have a bright reflective surface which give a mirror like image.  They are the most labour intensive mechanically finished surface with an obvious impact on cost and time of production.  As fl at product, mirror finishes are produced by post mill abrasive polishing of either hot rolled or cold rolled sheet or strip.

Although mirror finishes are only defined in standards for flat products, it is also possible to generate a mirror polish on surfaces where there is sufficient access for the grinders and polishing mops.  The exception to this is materials with large or variable microstructures such as some castings or heavily cold worked items or welds.  In these cases, it may not be possible to obtain a mirror surface with a clear image or a uniform lustre.

Mirror polished surfaces are produced by grinding with successively finer abrasives where the next grit size is not selected until all the scratches produced in the previous stage have been removed.  The surface is then buffed with “mops” (which may be soft or hard) and sticks compounded with binders and rouge of whose particle size depends on the required finish.  The buffing stage does not remove much material and, if there are scratches from earlier grinding stages, they will show up as rounded furrows.  Contamination with a larger grit particle will give isolated, but very unsightly scratches.

A mirror finish is the only one that will produce a clear image of its surroundings.  Finishes such as the cold rolled BA or an electropolished 2B or even a No 4 finish with a very low Ra that is then electropolished, will be brilliant and reflective but they will not form a sharp reflected image.

 

Specifications
Both ASTM A480 and EN10088-2 include mirror finish specifications called No 8 and 2P respectively.  Mirror finish is described as a non-directional finish which is reflective and has good image clarity.  The surface will be essentially free from grit lines due to the initial grinding stages but there will be visual differences between surfaces produced by different suppliers to these specifications.

For mirror finishes, requiring that the surface has a specific surface roughness (Ra) is not very useful.  Gloss measurements are a useful technique on fl at surfaces especially if both diffuse and specular reflection are measured.  Not surprisingly, diffuse reflectance is always higher. If a higher level of confidence is required for critical applications, then agreement on comparison with a finished sample in agreed conditions is recommended. It is the most reliable method of detecting random scratches.

Applications and Limitations
Mirror finish is most widely used for plates in presses, on the interior surface of moulds and also for small mirrors, reflectors and architectural panels.

The two primary limitations are:

• the most commonly used grades (304 and 316) are quite soft so that any cleaning process must avoid scratching the surface with residual dust or applied cleaning compounds, and

• large fl at areas of mirror polish throw scratches, grease or dirt markings into sharp contrast.

The first limitation is overcome by careful cleaning protocols using adequate water rinsing.  The effect of random marks and scratches is reduced if the surface is corrugated at the macro level described below when using surfaces that are texturised (single sided deformation) or embossed/rigidised (through thickness deformation).  However, while mirror sheet may be profi led, it is more common to apply profi ling treatments to cold rolled sheet.

Profiled or Patterned Surfaces
EN10088-2 uses categories 1M and 2M for sheet material that has been patterned on one side only.  The 1M group applies to hot rolled base materials while the much more common 2M applies to cold rolled base materials, usually with a 2B, 2D or 2R (BA) finish.  In corrosive environments it is essential to orient the pattern to allow free drainage.

Through Thickness Deformation
EN10088-2 lists 2W for cold rolled sheet that has been cold rolled into a through thickness corrugated  pattern. The cold work strengthens the sheet and may permit the use of thinner sheet.  The rigidity also helps control oil-canning, i.e. local buckling caused by thermal expansion during fixing or temperature changes during the year or day.  The surfaces are often described as embossed or rigidised.

Coloured Stainless Steel
Stainless steel can be painted provided that the surface is scrupulously clean and has sufficient profile to mechanically anchor the paint.  Using a stainless steel base metal offers the advantage that, even if the coating is damaged, any rusting is superficial and will not lead to long term structural failure as has occurred when protective coatings fail on steel or aluminium structures.

However, painted organic coatings are a clumsy means of colouring stainless steel.  If it is simply to be blackened, then the molten sodium dichromate process or a hot sulphuric acid treatment or even an electrodeposited and baked organic coating could offer greater durability.

Other colours are offered by an electrochemical deposition process that deposits and hardens an enhanced oxide film on the stainless steel although usually only on 304.  The colour depends on the thickness of the oxide and progresses from blue to gold to mauve and green with time of exposure.

The colour is similar to the interference colours in an oil slick or soap bubble with interference between the light refl ected from the top of the oxide and base metal.  In theory the colouring could be reproduced on any simple shape but in practice, it is only available on sheets.  The coated sheets may be deep drawn, formed, bent and fixed mechanically but welding destroys the coloured film.  While the oxide film is harder and more resistant to scratching than the basic 304 substrate, it is still susceptible to mechanical damage and so is not suitable in areas subject to heavy traffic.  Corrosion tests on blue coatings on 304 showed slightly improved resistance to atmospheric and acidic chloride exposure over the resistance of 304.

This article featured in Australian Stainless magazine - Issue 30, Autumn 2007.

Stairway to Stainless Heaven

Northern Stainless Director and Operations Manager Darren Colbert said a stairway to heaven for a Fannie Bay home in Northern Territory meant minimal upkeep in a potentially corrosive environment.

“We wanted low maintenance because he (the home owner) is only 1km from the ocean,” Darren said. “He is well shielded from the sea but we still electropolished - to avoid tea staining.”

Stairway to Stainless HeavenThe staircase used 560 kilograms of grade 316 stainless steel supplied by Atlas Specialty Metals in Berrimah. Standing 4.5metres high and stretching out 3.5metres, the structure was built to complement the handrails around the pool area as well as the balustrades around the upper level of the dwelling.

A great deal of individual attention was given to the stair treads, using 3 millimetres of stainless steel which was laser cut and punched. Further laser cutting was used to provide aesthetic features under each step. The two main stringers used 6-inch stainless steel pipes, which were electropolished to achieve their final look.

The end result was a spiraling stairwell from the pool area to the upper level of the home, which requires only minimal maintenance and looks simply gold!

This article featured in Australian Stainless magazine - Issue 39, Autumn 2007.

Nickel Mine Uses 400 Tonnes of Stainless Steel

When ASSDA Accredited Fabricator Nepean Engineering was awarded the tender for the manufacture of the stirring mechanisms for 10 thickeners for the Goro Nickel Mine in New Caledonia, they had no idea of the enormity of the venture. But having now completed the two-year undertaking they reflect on what has been their biggest stainless steel project to date.

 

 

Although the nickel mine was a massive development, Nepean Group Owner and Managing Director David Fuller admits the initial stages of commencement were a little “stop-start”.

“We won the tender 2 years before from GLV Australia Pty Ltd (Dorr-Oliver Elmco) but the project was cancelled,” he says. “We then had to re-tender and were lucky enough to win it again.”

Manufacturing finally commenced in August 2005 and was completed in March 2007.

Nickel Mine uses 400 tonnes of stainless steelDavid says the project resulted in 410 tonne of stainless steel product, including an additional 370 tonne of carbon steel. The contract export value was $10 million. Varying grades were used including 338 tonnes of 316L, 65tonne of 904L and 7 tonne of AL6XN. The thicknesses ranged from 1.6mm up to 80mm.

Six of the thickeners were 70 metres in diameter and required the manufacture of 33 metre long raking arms. Because a highly corrosion resistant material was needed where the nickel extraction occurred, Nepean Engineering used 904L for its high nickel and chromium content. The thick sections required meant that 316L and 904L were used to avoid sensitisation and the subsequent risk of intergranular attack.

Super-austenitic grade AL6XN with 6% molybdenum and high nitrogen, offered better corrosion resistance and was used in one of the smaller thickeners, which extracts cobalt. This material was imported from America.

When manufacturing commenced Nepean Engineering experienced quite a few challenges as a large amount of material was non-standard size.

“316L angle was unavailable so all angles were pressed from flat plate,” David says.

Pressing was performed across the grain. This required joining 2 x 8 metre sheets using sub arc welding so that the longer angles could run across the sheet. The sheets were then cut to fit the plasma cutter, which could handle 6 x 17 metres. Some of the angles were formed in Nepean's 1000 tonne press and others were subcontracted for specialist pressing.Nickel Mine uses 400 tonnes of stainless steel

Special dies were made for Nepean's press to allow larger angle radius. Furthermore, pipe unavailability due to wall thickness requirements meant up to 2 semi-circular half sections of pipe had to be pressed then sub arc welded together to achieve a die of the required length and diameter. For quality purposes, all welding required procedures. Nepean Engineering created a procedures manual for approval by the client.

Contamination from processing and handling was an issue that required focus. Nepean Engineering built a new factory dedicated to stainless steel with inserts at work stations, on forklift tines and on cranes plus separation sheets on presses and rolls to avoid cross contamination. All welds were pickled after fabrication. However, it became evident that not all contamination had been removed with further contamination also occurring due to airborne grinding particles. In order to provide a clean surface with a uniform overall appearance, flap disc grinding and garnet blasting was performed which removed any contamination, excess flux, heat tint and oxides.

With such a large quantity of stainless steel on site and with varying grades and material thicknesses, clear identification was imperative. Traceability was adopted on all parts and processes of the project with the introduction of a colour coding system to identify the different grades of stainless steel.

Material heat numbers were stamped on all components. Maps and naming schedules were used so that each component had a part number and could be identified on a drawing. A spreadsheet was produced to advise the client of the heat number of the plate from which each part was cut. This then could be traced to a material certificate to provide the chemical and mechanical properties of that particular plate or item.

Weld traceability was also adopted on all parts of the project. Again maps and naming schedules were used so that all welds could be identified. Each welder was assigned an identification number, which was then traced against the weld number and placed on a spreadsheet similar to the material traceability spreadsheet.

Other parameters traced were the type of wire used, wire batch numbers, flux type and batch and welding procedures.

Non-destructive testing (NDT) was employed with dye penetrant and ultra sonic tests on the non-magnetic, austenitic stainless steel components and magnetic particle and ultrasonic on the carbon steel components.

David Fuller said “the job was a major challenge but one that Nepean Engineering rose to”. “The experience we have acquired, along with the additional infrastructure built puts us in good stead for future projects of this magnitude.”

This article featured in Australian Stainless magazine - Issue 39, Autumn 2007.