Common Traps to Avoid

Posted 1 April 2006

Errors in stainless steel fabrication can be expensive and difficult to resolve. So a 'Get it right the first time' approach to stainless fabrication is necessary to gain the best result. Check the ASSDA website regularly for a local Stainless Steel Specialist.

ASSDA Accredited Fabricators - Ensuring the Best Result
ASSDA Accredited Fabricators are companies and individuals that have a common understanding of successful technical practices for fabricating stainless steel.

To ensure the highest standard in quality, Accredited Fabricators belong to the ASSDA Accreditation Scheme, an ASSDA initiative that is intended to achieve self regulation of the industry, for the benefit of both industry members and end users.

The Accreditation Scheme criteria requires all fabricators to conform to stringent standards of competence, training and education, personal and professional conduct, adhering to a Code of Ethics and a Code of Practice, and committing themselves to continuing competency development.

The Scheme gives owners and specifiers of stainless steel greater certainty that fabrications using stainless steel will be performed by technically competent industry specialists.

COMMON TRAPS TO AVOID

Surface damage, defects and contamination arising during fabrication are all potentially harmful to the oxide film that protects stainless steel in service. Once damaged, corrosion may initiate. Common causes of surface damage and defects during fabrication include:

Scratches and Mechanical Damage

Scratches and gouges form crevices on the steels surface, allowing entrapment of process reactants or contaminants, providing ideal locations for corrosion. Scratches may also contain carbon steel or other contaminants embedded by the object that caused the scratch.

Scratches will also raise customer concerns in situations where appearance is important. Mechanical cleaning is the most effective way to remove them. Prevention would be better.

SURFACE CONTAMINANTS

Common contaminants likely to attack stainless steel include carbon steel and common salt. Dust and grime arising during fabrication may contain these contaminants and should be prevented from settling on stainless steels.

Oil, grease, fingerprints, crayon, paint and chalk marks may also contain products that can provide crevices for localised corrosion and also act as shields to chemical and electrochemical cleaning. They should be removed.

Residual adhesives from tape and protective plastic sometimes remain on surfaces when they are stripped. Organic solvents should remove soft adhesive particles. If left to harden, adhesives form sites for crevice corrosion and are difficult to remove.

The most frequently encountered fabrication problem is embedded iron and loose iron particles, which rapidly rust and initiate corrosion. Other common sources of contamination are abrasives previously used on carbon steel, carbon steel wire brushes, grinding dust and weld spatter from carbon steel operations, introducing iron filings by walking on stainless steel and iron embedded or smeared on surfaces during layout and handling. All should be avoided.

WELDING

The high temperature characteristics of welding can introduce surface and other defects which must be addressed.

Undercut, spatter, slag and stray arc strikes must be minimised as they are potential sites of crevice corrosion. General cleanliness and removal of potential carbon contaminants such as crayon marks, oil or grease is important in obtaining good weld quality. It is also important to remove any zinc that might be present.

HEAT TINT AND SCALE

Heat tint and scale occur when stainless steel surfaces are heated to moderately high temperatures in air (350⁰C+) during welding.

Deleterious oxides of chromium may develop on each side and on the under surface of welds and ground areas. These oxides lower the corrosion resistance of the steel and during their formation the stainless steel is depleted of chromium. The oxidation and the portion of the underlying metal surface with reduced chromium should all be removed by mechanical, chemical or electrochemical means to achieve the best corrosion resistance.

DISTORTION

Stainless steel has a relatively high coefficient of thermal expansion coupled with low thermal conductivity, at least compared with carbon steel. So, stainless steel expands rapidly with the input of heat that occurs during welding and the heat remains close to the heating source. Distortion can result. Distortion can be minimised through using lowest amperage consistent with good weld quality, controlling interpass temperatures and using controlled tack welding, clamping jigs with copper or aluminium backing bars as heat sinks on the welds.¹

REMOVAL OF SURFACE CONTAMINATION

There are three methods of repairing the surface of stainless steel.

MECHANICAL CLEANING

Wire brushing should only be done with stainless steel bristles that have not been used on any other surface but stainless steel. Clean abrasive disks and clean flapper wheels are commonly used to remove heat tint and other minor surface imperfections. Also effective is blasting with stainless steel shot, cut wire or new, iron-free sand (garnet is a common choice).

CHEMICAL AND ELECTROCHEMICAL CLEANING

Embedded iron, heat tint and some other contaminants can be removed by acid pickling, usually with a nitric-hydrofluoric acid mixture or by electropolishing. These processes remove, in a controlled manner, from the affected areas, the dark oxide film and a thin layer of metal under it, leaving a clean, defect-free surface. The protective film reforms after exposure to air.

Passivation

Passivation involves treating stainless steel surfaces with, usually, dilute nitric acid solutions or pastes. This process removes contaminants and allows for a passive film to be formed on a fresh surface, following grinding, machining etc.

Care must be taken. Nitric acid treatments will remove free iron, but not iron oxide contaminants. Passivating, unlike pickling, will not cause a marked change in the appearance of the steel surface.

INSTALLATION

Stainless steel is best installed last to avoid damage during construction. Also, careful storage and handling including protective coating films are required prior to and during installation to minimise risk of damage to the stainless steel structure.

A primary goal of the stainless steel industry is to have finished products put into service in a 'passive' condition (free of corrosive reactions). Stainless steel is a robust and relatively forgiving material, but adherence to informed, good practice will ensure satisfaction for customers and suppliers alike.

Understanding stainless steel is important to its successful application. Ask your stainless steel representatives whether they have successfully completed ASSDA's Stainless Steel Specialist Course. Their commitment to product knowledge will be your key to success.

REFERENCES

1. NI & Euro Inox (1994) Design Manual for Structural Stainless Steel NiDI Ref. No. 11 013

RESOURCES

• AS 1554.6 'Welding Stainless Steel for Structural Purposes'
• Australian Stainless 2005 Reference Manual, ASSDA
• Stainless Fabrication Group, New Zealand, 'Code of Practice for the Fabrication of Stainless Steel Plant and Equipment'
• Nickel Institute (NI) 'Cleaning Stainless Steel Surfaces Prior to Sanitary Service'
• ASSDA - www.assda.asn.au
• BSSA - www.bssa.org.uk
• Nickel Institute - www.nickelinstitute.org

ASSDA acknowledges the assistance and contribution of Mr Peter Moore, Technical Services Manager of Atlas Specialty Metals in the production of this article. Photographs courtesy of Peritech and Outokumpu.

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

Transforming apprentices into stainless steel specialists can be a challenging but rewarding experience for employers seeking to improve quality, retain staff and increase profitability.

Built on Reputation

Alistair Patterson has a flair for the food and beverage industry that borders on obsession. As the sole proprietor for ASSDA Accredited Fabricator, Australian Stainless Products, Patterson's reputation within the industry means when projects are on, he is onto it!

Australian Stainless Products are custom manufacturers of quality stainless steel food, beverage and pharmaceutical process products and equipment.

Established more than 20 years ago, Australian Stainless Products started out building basic dairy machinery, primarily small repairs and maintenance of equipment for a few of the local food processing equipment plants.

“Back then the business was basically building milking machinery. We did small repairs and maintenance and equipment for a few of the local food processing plants in the area.”

Now, the Melbourne-based company manufactures original equipment from large tanks, vessels and hoppers including process equipment up to 50,000 litre capacity.

Working with a small but loyal client base, Patterson has worked with some engineering consultants such as dairy equipment supplier DeLeval for more than a decade.

“It's quite a small industry. We operate by word of mouth and references of jobs. It takes a long time to build, grow and develop a business within this industry,” said Patterson.

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

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.

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.

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.

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.

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 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	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: 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 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.

Unveiled 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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.