Specifying Steel Corrosion Protection

Steel ConstructionJournal of the Australian Steel Institute

ISSN 0049-2205 PRINT POST APPROVED PP255003/01614

Specifying corrosionprotection on steel

Volume 45 Number 1 – December 2011

STEEL CONSTRUCTION VOLUME 45 NUMBER 1 – DECEMBER 2011 1

STEEL CONSTRUCTION—EDITORIAL

A fundamental consideration impacting on cost and long term sustainable outcomes is the assessment of the working environment and evaluation of the necessary protective systems to ensure that a steel structure will meet its lifecycle requirements for functionality and aesthetics.

The following two papers by Dr Rob Francis provide a holistic view into corrosion protection issues to be considered by structural engineers and specifiers using steel. The first paper provides background on the development and use of Australian atmospheric corrosivity standard AS 4312, an important reference which drives the selection of appropriate corrosion protection. The new standard documents a range of zones throughout Australia and assigns each a corrosivity level, helping to standardize corrosion protection materials and simplify selection without the cost penalties of over-protection. This paper is based on one presented at the Australasian Corrosion Association Conference held in November 2007.

The second paper looks at defining coating specifications to meet the project requirements, which include the corrosivity environment in which the project is located. The paper provides a balanced analysis of the major types of coating systems available and their range of applicability and is therefore an important reference in a subject area that is often confusing, particularly to younger engineers.

Dr Rob Francis is a corrosion and coating specialist with Aurecon's Materials Technology Group in Melbourne. He has over 20 years of industrial and research experience in general corrosion and protective coatings and is Chairman of the Standards Australia committee which prepared AS/NZS 2312 on protection of structural steel by coatings.

Dr. Peter Key National Technical Development Manager, Australian Steel Institute

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2 STEEL CONSTRUCTION VOLUME 45 NUMBER 1 – DECEMBER 2011

AS 4312: AN AUSTRALIAN ATMOSPHERIC CORROSIVITY STANDARD

by

R A Francis Aurecon, South Melbourne, Victoria, Australia

SUMMARY Engineers, designers and specifiers need to be aware of the corrosiveness of the environment in which they are working when selecting materials, coatings, fasteners and other items exposed to the exterior environment. Many standards and literature from manufacturers, such as those for selecting protective coatings, coated sheet metal products and fasteners, contain guidelines to enable the user to determine atmospheric corrosivity. Identification of the correct environment is important to ensure that the user selects adequate corrosion protection, without the cost penalties of over protection. AS 4312 Atmospheric corrosivity zones in Australia has been developed to standardise corrosivity zones which can apply for a range of corrosion protection materials and coatings. This will simplify selection of such products, and make certain that users are using the most accurate and up-to-date data available. This paper provides an overview of the standard, the information it contains and how it can be used. This standard is believed to be the only one of its type in the world, and should enable specifiers and users in many fields to gain an awareness of atmospheric corrosivity and select optimum materials, coatings and other corrosion protection systems.

1 INTRODUCTION

Knowing the corrosivity of the atmosphere is of critical importance to many in the corrosion control industry, from specialist practitioners such as paint and material specifiers through to a wide range of engineers and others responsible for buildings, structures, machinery, etc. that will be exposed to a specific environment. For example, coating specifiers will normally specify a more complex, thicker coating system in a severe industrial or marine environment than in a mild interior environment. Repair and maintenance requirements in an industrial plant are usually more urgent and more complicated in a severe environment than in a mild environment. There are a number of grades of alloys such as stainless steel where selection of the optimum grade often depends on the exposure environment. Clearly an understanding of the factors that influence aggressiveness of the environment to coatings and materials is of great benefit to many within and outside the corrosion protection industry. While such information may be available in the scientific literature or manufacturers’ literature, placing it in a standard gives it much greater credibility and easy availability.

This paper looks at the development of a standard for determining corrosivity zones in Australia, a brief overview of the zones, how the standard is used and how it relates to corrosivity discussions in other Australian standards.

2 DEVELOPMENT OF A CORROSIVITY STANDARD

Information on atmospheric corrosivity in Australia has been available in AS/NZS 2312 [1] for many years. This standard, designed for selection of protective coatings for steelwork exposed to the atmosphere, requires the specifier to determine the environment as the first stage in coating selection. This standard contains a description of corrosion zones and an appendix to assist the user in determining the correct zone. In recent years, International Standards have been developed to categorise corrosivity, and AS/NZS 2312 has moved to adopt the ISO categories to enable the corrosion protection industry to use internationally recognised corrosion zones. The categories in AS/NZS 2312 have been accepted throughout industry, shown by the fact that the AS/NZS 2312 categories and approach have been adopted by many other Australian standards.

The success of the system has led to separation of the corrosivity section from AS/NZS 2312 in the form of a recent standard, AS 4312—2008 Atmospheric corrosivity zones in Australia. This standard takes the


approach and information from AS/NZS 2312, but expands it significantly to make categorisation easier, and provide much more information to the user. As a separate standard, it also makes it easier to reference when developing standards that require consideration of atmospheric corrosivity. It is not intended that the discussion on corrosivity and categories be removed from the individual standards, but rather that this newer standard provide much more detailed information for the user if and when required.

The starting point for determination of corrosion zones is ISO Standard 9223 and related standards. ISO 9223 [2] and ISO 9224 [3] define corrosion zones. There are two main methods to determine their corrosivity. ISO 9225 [4] determines the zone by measuring the time of wetness, chloride concentration and SO2 levels. ISO 9226 [5] uses corrosion rates of metals to determine the corrosion zone. The relationship between these various standards is shown in Figure 1.

ISO 9223Classification of

atmospheric corrosivity

Method 1:Classification in termsof time of wetness and

pollution

ISO 9223Corrosivitycategories

Method 2:Classification based

on corrosion ratemeasurement

ISO 9225Measurement of

pollution

ISO 9224Guiding values ofcorrosion rate for

each category

ISO 9226Determination ofcorrosion rate of

standard specimens

Figure 1: Family of ISO Corrosivity standards

Whichever method is used to determine corrosivity, atmospheres are divided into one of five categories from C1 to C5 in ISO 9223 in increasing severity of the environment, as shown in Table 1. AS 4312 expands these categories slightly. The C5 zone is split into C5M and C5I (Marine and Industrial) to account for the differing effects of marine and industrial environments on some coatings, even though the corrosion rate of steel may be the same. This provides consistency with AS/NZS 2312 and ISO 12944.2 [6]. In addition, a Tropical (T) category is included to account for the effect of a tropical environment on some paint coatings, which does not relate to corrosion rate of steel. This category is unique to Australian standards.

Table 1: Corrosivity categories according to AS 4312 and ISO 9223

AS 4312 Category

ISO 9223 Category

Corrosivity Steel corrosion rate (µm/yr)

Typical environment

C1 C2 C3 C4

C5M C5I T

C1 C2 C3 C4 C5 C5 –

very low low

medium high

very high – marine very high – industrial

–

<1.3 1.3–25 25–50 50–80

80–200 80–200

–

dry indoors arid/urban inland

coastal or industrial sea-shore (calm) sea-shore (surf) severe industrial

tropical inland


While the ISO standards provide an established and well recognised method of categorising corrosivity, they are not without their weaknesses and limitations. These are discussed in detail by King and Duncan [7]. One of these weaknesses is the poor correlation between corrosivity zone as calculated from time of wetness and pollution levels, and that measured from corrosion rate of exposed metal specimens. Another is that corrosivity zone, as determined by corrosion rates on different metals, does not correlate. For example, a zone may be designated as C3 according to steel corrosion rate, but C2 or C4 according to zinc corrosion rate. AS 4312 overcomes this limitation by only categorising zones according to steel corrosion rates, although it does not specifically forbid use of one of the other methods. However, most of the experimental work done in Australia is with steel so this is unlikely to be a major issue. Furthermore, there is little data on time of wetness, salt deposition and SO2 concentration available in this country to use these levels to determine corrosion zone.

3 CORROSIVITY SURVEYS

Surveys of corrosivity in Australia have been carried out for many years, and the significant amount of data available is one of the reasons that a standard such as this can be produced for such a large country. It is not the intention of this paper to list or review the work that has been done, as the standard contains a list of readily available technical papers in Appendix C. The surveys carried out by George King, John Moresby and others at CSIRO, especially for Melbourne, Newcastle and the state of South Australia, have been especially beneficial for the development of this standard. This work has been included in the standard, simplified to show only the corrosion categories. Corrosion rates at various sites around the country from numerous other surveys are included in a table in the standard. References are given so that the user can investigate the original work if so desired.

The corrosion zones in Australia are described in the standard. It points out that proximity to the coast is the single most important factor. If there is no marine influence, then corrosion rates are generally low, and such areas would normally be in Category C2. Marine influence can fall away within a kilometre of the coast on a sheltered bay when winds and topography are favourable. However, salt deposition and resulting high corrosion rates can be found up to fifty kilometres inland in some areas, such as south eastern South Australia. As a basic rule, any site more than 50 kilometres from the coast will be in the Moderate C2 category. This covers a vast proportion of the Australian land mass, but as most of the population of the country live within 50 kilometres of the sea, they are potentially in one of the more severe categories. The corrosivity category will not only depend on distance from the shoreline, but also whether seas are rough or quiet, as shown in Table 2. Regions right on the coast with rough seas will be in the C5M (very severe marine) category as there is significant salt deposition. This extends inland by a small distance, generally of the order of 0.3 kilometres, but may be as much as 0.5 kilometres when conditions are severe. The next region inland from rough seas is the C4 region, and extends to around one kilometre inland. Regions right on the coast (within 0.1 kilometre of the shoreline) on sheltered bays are in C4. On sheltered bays, the marine influence has disappeared within a kilometre or so of the shoreline.

Table 2: Selection of corrosivity category according to distance from shoreline

Distance from shoreline Rough seas within 20/50* kilometres

No rough seas within 20/50* kilometres

0 to 0.1 km C5M C4 0.1 to 0.3/0.5* km C5M C3 0.3/0.5* to 1.0 km C4 C3 1.0 to 20/50* km C3 C2 (T)

> 20/50* km C2 (T) C2 (T) Notes: (1)

(2) T = *

Use Tropical category for sites in tropical region of the country. Use the higher figure when winds are strong and/or topography conducive to salt travel inland.

Table 2 shows the importance of distinguishing between local rough or quiet seas. The difference is one corrosivity category, or two in the case of the region from 0.1 to 0.5 kilometres inland. There are, of course,


some regions where the distinction between rough and quiet seas is not clear. In the gulf regions of South Australia for example, the seas are rough at the southern end, but quieter further north. Adelaide has surf beaches to the south, but the seas to the north of the metropolitan area are relatively benign. The survey carried out for South Australia shows that in such situations it would be best to estimate zones as somewhere between these two extremes.

The standard contains maps of major regions of Australia where surveys have been carried out, namely Melbourne, Newcastle and South Australia. In addition, maps are included of the Sydney, Brisbane and Perth metropolitan areas. Delineation of zones in these three regions is based on estimates and behaviour of regions where surveys have been carried out. It should be stressed that the borders are only estimates for these regions, and users should be aware of limitations. These are discussed below. Figure 2 summarises the maps given in the standard, indicating the major zones. No attempt has been made to determine the extent of the very severe marine zone on these maps, which cannot be resolved on this scale.

Figure 2: Corrosivity zones in some Australian centres according to AS 4312

4 MICRO-ENVIRONMENTS AND DESIGN FACTORS

The corrosivity surveys used to delineate corrosivity zones determine the effect of the macro-environment at a given site, that is, the environment generated by normal weather patterns. The important factors influencing macro-environmental corrosivity are identified as time of wetness and salt deposition. These are discussed in detail in the standard, and the research work listed in Appendix C of the standard. However, the standard notes that micro-environmental or micro-climatic factors at a site, and design features of the structure under consideration, can interact to convert a mildly corrosive site into a more severe one. The important factors are listed in Table 3, along with their effect on corrosivity. It should be noted that SO2 pollution (‘acid rain’) is considered as a micro-environmental factor in Australia, unlike many other parts of


the world where it is considered a macro-environmental factor. Australia has been fortunate that its fossil fuels have historically been low in sulphur, and furthermore that the influence of such pollutants has dropped over the past 30 or so years [8]. The table shows that micro-environmental factors will generally increase corrosivity. However, regions sheltered from rain washing generally show higher corrosion rates, but in regions with little atmospheric contamination (Category C2), exposure to rain or washing can increase corrosion rates. The major micro-environmental factors all increase corrosivity, and the standard recommends moving up to at least the next corrosivity category if any of these influence the structure. As most engineering structures will have flat ponding surfaces, if not influenced by the other factors, moving up to the next category will be the usual procedure.

5 METALS OTHER THAN STEEL

Section 2 of the standard contains a brief summary of the atmospheric corrosion properties of metals other than steel, including stainless steel, copper, zinc and aluminium. It refers to the relevant Australian standards for details. The standard notes that these metals have much lower corrosion rates than steel, and that generally their corrosion rate will increase as the environment becomes more severe. Unlike ISO 9223, the standard does not accept a numerical relationship between steel corrosion rates and corrosion rate of zinc, copper and aluminium. Corrosivity of the environment is important in selecting such alloys for atmospheric use. More highly alloyed stainless steels, for example, are required as the environment becomes more severe, especially with regard to chloride environments. The standard does not cover the useful ‘Pitting Resistance Equivalent (PRE)’ which can be used to select stainless steels. This allows comparison between different grades with respect to pitting and crevice corrosion, the most important forms of corrosion in severe environments. The PRE formula depends on the amount of chromium (Cr), molybdenum (Mo) and nitrogen (N) in the stainless steel. Higher PRE presents better resistance to pitting and crevice corrosion. PRE can be estimated using the following formula:

PRE = % Cr + 3.3 x % Mo + 16 x % N

Table 3: Micro-environmental factors influencing corrosivity

Feature Cause Examples Effect on corrosivity Micro-environmental • Industrial pollutants SO2, other corrosive

gases Around and within fossil fuel burning industries

Increase

• Chemicals Chemical salts, fertilisers, farming wastes

Industrial activities, farming activities

Increase

• Abrasion and impact Wind erosion, traffic, livestock

Dusty regions, farms, handling

Increase

Design • Regions sheltered from

rain or regular washing Build up of salts and pollutants

Under canopies, bridge soffits

Increase in severe environments Decrease in mild environments

• Prolonged surface wetness

Increased time-of-wetness Ponding areas, shaded regions

Increase

Table 4 provides a rough rule-of-thumb giving required PRE, and example stainless steels, for the various corrosivity categories. It must be recognised that this is a very simplified approach, and actual selection requires consideration of factors such as surface finish, presence of welding scale and maintenance regimes.

Table 4: Selection of stainless steels based on PRE number

Corrosivity category Corrosivity description PRE Example stainless steels C1 Very low <15 409, 3CR12 C2 Low 15–20 430, 304 C3 Medium 20–25 444, 316 C4 High 25–30 2304 C5 Very high >30 904L, 2205


6 HOW THE STANDARD IS USED

There are three methods of determining the corrosivity zone for a given site in Australia. These are:

(a) Where surveys have been done, the corrosivity zone can be determined from the steel corrosion rate.

(b) If the site has similar climatic and geographic features (including proximity to the sea) to a site where a survey has been carried out, then the zone can be estimated by analogy.

(c) If surveys have not been carried out at the site, or at an analogous site, then the corrosivity zone will need to be determined from first principles.

6.1 Zones using corrosivity surveys

Where surveys have been carried out, it is a relatively easy task to determine corrosivity zone. If, for example, the one year steel corrosion rate is 40 microns per year at the site of interest then, according to Table 1, the corrosivity zone is C3. The standard contains maps of the Melbourne and Newcastle metropolitan areas, and the southern region of South Australia, adapted from the CSIRO surveys. Appendix A of the standard contains a list of 89 locations around the country where surveys have been carried out, giving their corrosion rate, distance from the sea and corrosivity zone. The user must be aware that proximity to the sea is critical as indicated in Table 2, and a given town or suburb near the coast could be in any one of three different corrosivity categories.

Even where surveys have been carried out, the user needs to be aware of problems using experimentally determined corrosion rates. There are two main problems with using experimental results.

Firstly, considerable variation in results can arise when carrying out surveys at a given site. Some of these variables are described below:

When using steel, use of a low copper alloy steel (known as BISRA steel) overcomes the effects of slight variations in chemical composition of the steel on corrosion rate, and this has been used in most surveys in Australia. However, the corrosion rate determined with this material needs to be ‘converted’ to an equivalent corrosion rate of mild steel. There is no accepted conversion constant, but BISRA steel tends to show a rate of 20 to 40 per cent less than mild steel.

Surveys are often carried out over periods of time other than one year. Two year corrosion rates are reckoned to be about 20 per cent less than one year rates, but again there is no accepted figure. For other periods of time, other estimates must be performed.

There are many experimental variations which can significantly influence the corrosion rate obtained. These include specimen orientation, height above sea level, surface finish and others. Appendix B of the standard discusses these factors, noting their influence as either major or minor. This appendix refers to the recent work of Melchers and Jeffries [9] which showed a variation of corrosion rate from 300 to 600 microns per year at a severe marine site just by varying some of these factors. LaQue, after investigating factors that influence atmospheric corrosivity, concluded: “The factors that influence atmospheric corrosion of test specimens are so many and so diverse that one must conclude that results of tests of this sort can have only a limited quantitative status” [10]. Corrosivity figures from such investigations must be considered only as approximate and small differences are not significant. However, the semi-quantitative ISO categories are probably sufficiently accurate to distinguish between significant environmental corrosivity groups, although the borders between them are arbitrary.

It should be noted that the standard is not designed for those carrying out such surveys although it has much useful information, such as a list of work carried out in Australia in Appendix C of the standard.

The second important factor is that corrosivity at a given site can and will change over time. Perhaps the most important change has been a reduction in the amount of atmospheric pollution over the past fifty years


or so. Polluting plants have closed down or reduced emissions, and any sites where pollution was a major contributor to corrosivity will show reduced rates for more recent surveys. For example, the Newcastle corrosivity map shows “islands” of high corrosivity around the steelworks and Boolaroo smelter. Both have since closed, and the corrosivity would now be expected to be at a background level. Furthermore, the standard quotes the early work of Egan [11] who carried out surveys at various industrial sites in 1971. Many of these sites would be expected to have changed corrosivity. For example, Egan quotes a steel corrosion rate of 30 microns per year for the Adelaide suburb of Woodville, putting it in the ISO C3 category, while a survey carried out by CSIRO only ten years later [12] showed a corrosivity nearly half this for the same suburb, putting it in the ISO C2 category. Furthermore, climate changes now believed to be taking place will mean changes to time of wetness, winds and other factors which could see changes to corrosivity of a given site. The figures in the standard must not be seen as fixed, but rather a starting point only.

6.2 Zones by analogy to surveys

If an actual survey has not been carried out, the next alternative would be to attempt to find a site or area with similar environmental conditions resulting in a similar corrosivity. For example, it is reasonable to assume that places along the coast of NSW from the Victorian border to the Gold Coast will have similar behaviour to that determined at Newcastle. The prevailing winds are from the south-east and the temperature, rainfall and humidity are similar. The crucial factor would be distance from the coast. The map of Sydney in the standard has been drawn based on the Newcastle experience, noting that the escarpment at the west of the city would be a natural boundary between the C3 and C2 regions where it is relatively close to the coast. Other places along the east coast could be expected to show similar behaviour.

Brisbane is rather difficult to predict, as it is more humid, but against this has the sheltering effect of the Stradbroke and Moreton islands offshore minimising salt deposition. The map in the standard is a best estimate based on survey results and estimated behaviour. It is less corrosive than regions from the Gold Coast south, as there is no breaking surf, but more corrosive than the sheltered Melbourne region. Similarly, the map of Perth in the standard is a best estimate from survey results and estimated behaviour.

6.3 Zones from first principles

If a survey has not been done, and there is no existing site analogous to the desired site, the user will need to determine the classification from first principles. The standard provides some information in Section 4. There is a flow chart which should assist, working through the zones in a systematic way, similar to the approach described above. If the site is more than 50 kilometres from the coast, the corrosivity is C2, or Tropical in the northern part of the country. For those areas within 50 kilometres of the coast, the next decision to be made is whether the nearest seas are considered best as rough or quiet. It is then best to work through the categories, looking at the most severe category first, and work down from this until the most reasonable estimate can be made. With the figures obtained from surveys carried out across the continent, it should be possible for the user to come up with a realistic estimate. For critical applications, a conservative approach would be required, using the more severe category if there is any doubt.

7 COMPARISON WITH OTHER STANDARDS AND CLASSIFICATIONS

Appendix D in the standard is a brief summary of corrosivity information in other Australian standards. AS/NZS 2312 has generally been the major source of corrosivity information in an Australian standard, and the appendix contains a table relating classifications in earlier versions of the standard to later versions, as well as the ISO classification. The main change that has occurred over the years is recognition of the significant variation in corrosivity within a ‘marine’ environment. In the 1994 version of the standard, for example, there was a mild and a moderate category, both largely covered by current C2. However, there was one ‘marine’ category which would cover corrosivities given in C3, C4 and C5 of the current standard, that is, a range with steel corrosion rates varying from 25 to 200 microns per year. It is clear that adoption of zones based on corrosion rates has had a major effect on the way that corrosion environments are now recognised.


The Appendix also notes that the classification used in AS/NZS 2312 has generally been adopted by other standards, such as anodising and coated steel products. It also notes that the recent development of standards with corrosion resistance performance requirements, such as for lintels [13] and self tapping screws [14], can be related to environmental corrosivity. It is expected in the future that this new standard will become the central reference for other standards, providing one consistent and up-to-date reference point.

One standard with a corrosivity classification not mentioned in the new standard is AS 3600 [15] and related standards concerning concrete. These define various exposure classifications which are intended to relate to required properties of concrete, such as strength and cover to reinforcement. In an aggressive marine environment, for example, a high strength concrete with significant cover to reinforcement is required to minimise risk of chloride diffusion through the concrete causing rusting of the reinforcement and spalling of the concrete. While degradation of concrete does not directly relate to steel corrosivity, the main reason for this classification is to prevent corrosion of reinforcement, which is influenced by the same factors as corrosion of steel in the atmosphere. A summary of the classifications in AS 3600 and related AS 4312 categories is given in Table 5. This shows that the concrete standards consider that there is a need for only two marine environments, whether the structure is less than or more than one kilometre from the coast. It does not distinguish between rough sea and quiet seas, and does not recognise the extremely high corrosivity found within a few hundred metres of rough seas. Ignorance of these facts must mean that many structures in marine environments are either under-designed or over-designed, with possible serious safety, maintenance and economic consequences. It is hoped that the concrete industry will note the content of this new standard and make the required changes.

Table 5: Corrosivity category according to distance from shoreline for AS 4312 and AS 3600

Distance from shoreline AS 4312

Rough seas within 20/50* kilometres

AS 4312 No rough seas within 20/50*

kilometres

AS 3600 exposure classification for

reinforced concrete 0 to 0.1 km C5M C4 B2 0.1 to 0.3/0.5* km C5M C3 B2 0.3/0.5* to 1.0 km C4 C3 B2 1.0 to 20/50* km C3 C2 (T) B1 > 50 km (tropical) Tropical Tropical B1 > 50 km (industrial) C2 (C3, C4, C5 if severe) C2 (C3, C4, C5 if severe) B1 > 50 km (temperate) C2 C2 A2 > 50 km (arid) C2 C2 A1

Note: * Use the higher figure when winds are strong and/or topography conducive to salt travel inland.

8 CONCLUSIONS

This paper has described the Australian standard on atmospheric corrosivity, AS 4312. It has described the development of the standard, the information contained, how it is used, and how it relates to other Australian standards with discussions on corrosivity. This standard should enable those making decisions on selection of corrosion control strategies for atmospheric exposure to quickly, simply and accurately determine corrosivity.

9 ACKNOWLEDGEMENT

The author thanks the members of Standards Australia committee MT14/5 for their contributions to the standard.


10 REFERENCES

[1] Standards Australia/Standards New Zealand, AS/NZS 2312:2002, ‘Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings’.

[2] International Standards Organization, ISO 9223:1992, ‘Corrosion of metals and alloys—Corrosivity of atmospheres—Classification’.

[3] International Standards Organization, ISO 9224:1992, ‘Corrosion of metals and alloys—Corrosivity of atmospheres—Guiding values for the corrosivity categories’.

[4] International Standards Organization, ISO 9225:1992, ‘Corrosion of metals and alloys—Corrosivity of atmospheres—Measurement of pollution’.

[5] International Standards Organization, ISO 9226:1992, ‘Corrosion of metals and alloys—Corrosivity of atmospheres—Determination of corrosion rate of standard specimens’.

[6] International Standards Organization, ISO 12944.2:1998, ‘Paints and varnishes—Corrosion protection of steel structures by protective paint systems—Part 2: Classification of environments’.

[7] King, G.A. and Duncan, J.R. 1998, ‘Some apparent limitations in using the ISO atmospheric corrosivity categories’, Corrosion & Materials, vol. 23, no. 1, pp. 8–14 & 22–25.

[8] Bartlett, D.J. 2001, ‘Industrial pollution and its impact on corrosion and corrosion mitigation practices’, Corrosion and Prevention 2001, Australasian Corrosion Association, Newcastle, paper 044.

[9] Jeffrey, R. and Melchers, R.E. 2006, ‘Early observations of corrosion losses for steels at a severe marine atmospheric site’, Corrosion and Prevention 2006, Australasian Corrosion Association, Hobart, paper 028.

[10] LaQue, F.L. 1964, ‘Precautions in the interpretation of corrosion tests in marine environments’, Industrie Chimique Belge, no. 11, pp. 1177–1185.

[11] Egan, F.J. 1971, ‘Effect of environmental factors on the corrosion of steels’, Australasian Corrosion Engineering, vol. 15, no. 6, pp. 9–16.

[12] Martin, K.G. and King, G.A. 1981, ‘Corrosivity measurements at some Australian cities’, Corrosion Australasia, vol. 6, no. 4, pp. 10–15.

[13] Standards Australia/Standards New Zealand, AS/NZS 2699.3:2002, ‘Built in components for masonry construction—Lintels and shelf angles (durability requirements)’.

[14] Standards Australia, AS 3566.2—2002, ‘Self drilling screws for the building and construction industries—Corrosion resistance requirements’.

[15] Standards Australia, AS 3600—2001, ‘Concrete structures’.

[16] Standards Australia, AS 4312—2008, ‘Atmospheric corrosivity zones in Australia’.


PRODUCING COATING SPECIFICATIONS THAT WORK

by

R A Francis Aurecon, South Melbourne, Victoria, Australia

God said to Noah: make yourself an ark . . . and coat it with pitch inside and out.

Genesis 6:14

Noah’s ark may be the earliest example of the selection and written specification of a quality coating and there is no doubt that the resultant coating performed the task required of it. Indeed, until relatively recently, we were still seeing coating specifications for structural steel along the lines of ‘wire brush the surface and apply two coats of good quality paint’, little advancement over that used by Noah. However, conditions are rather different 6000 years on. We require coatings to withstand environments other than heavy rainfall and wear and tear by animals. We require coatings to last longer than 40 days and 40 nights. Unlike Noah, we have environmental and health and safety regulations to obey and coating contractors and paint company representatives to deal with. Perhaps most importantly, the Almighty generally is not called upon to select coatings and write the specification, so mistakes can be made.

A good coating specification is essential if steel structures are to continue to function as designed. This paper describes some of the factors that the specifier must consider when selecting coatings to protect steelwork, and some typical specification clauses. It follows the content of AS/NZS 2312 [1], and that document should be an essential reference for anyone selecting and specifying coatings for steel in our part of the world.

1 FACTORS INFLUENCING COATING SELECTION

The most important characteristic of a coating system for protecting a steel structure against corrosion would normally be the ability to provide protection to the substrate for as long as possible, that is, maximum durability. However, there are many other factors that must be considered and some of these are described below.

(a) Environment

The environment is perhaps the single most important factor affecting durability of a coating system. A coating which lasts a few months in a severe marine environment may last decades in a mild environment. In addition, acidic environments can be corrosive to zinc coating systems which have excellent durability in neutral environments. The important environmental factors influencing corrosion in atmospheric environments were discussed in an earlier paper [2]. Recently, a new standard [3] has provided more details on determining local corrosivity in Australia, including provision of corrosion maps of major centres. This standard uses the ISO corrosivity categories which are becoming widely used around the world for selecting methods of corrosion control for structures and other items exposed to the atmosphere. The corrosion categories are summarised in Table 1.


Table 1: Corrosivity categories according to AS 4312 and AS/NZS 2312

AS 4312 category

AS/NZS 2312 category Corrosivity Steel corrosion rate

(µm/yr) Typical environment

C1 A very low <1.3 dry indoors C2 B low 1.3–25 arid/urban inland C3 C medium 25–50 coastal or mild industrial C4 D high 50–80 sea-shore (calm)

C5M E-M very high – marine 80–200 sea-shore (surf) C5I E-I very high – industrial 80–200 severe industrial T F – – inland tropical

(b) Colour and gloss

Many of the most corrosion resistant coatings, such as metal spray, galvanizing and inorganic zincs are only available in matt grey. Even when considering coatings applied to minimise the effects of corrosion, there are many situations where colour or gloss or both are required and such coatings are not appropriate. Some reasons for requiring colour, even for nominally protective coatings, include:

Colour is often necessary for logos and identification Colour can brighten dark areas and hide ugly areas Colour is required for safety, heat reflection, visibility, etc Colour and gloss may enhance public image, provide visual impact, etc.

(c) Shop or site application

Many structures are fabricated and coated in a shop, taken to site and erected. In such cases, coatings would normally be applied in a shop, with only some touch up required on site. Such an approach will normally provide optimum durability because of the following advantages:

Coating is carried out under controlled conditions meaning less contamination from smoke, dust, etc Areas which become inaccessible can be coated Inspection is easier and more thorough There will not be problems working around other trades, so fewer ‘extras’ Coating should not be affected by bad weather.

Some coatings, such as galvanizing, are only applied in a shop. The main concerns with shop-applied coatings are that the item must be small enough to be able to be transported and there will always be a problem with site touch up. The range of coatings that can be site-applied is less than for those designed for shop application.

(d) Surface preparation and coating application methods

Most of the best quality primers must be applied to a blast cleaned surface. If blast cleaning is not permitted for environmental or other reasons, then only a limited range of products is available. Similarly, many modern high performance coatings must be applied by spray. At best, brush or roller can only be used for small areas with such coatings. If spraying is not permitted for environmental or OH&S regulations, concerns with overspray or other reasons, then selection will be from a limited number of coating products.

Section 7 of AS/NZS 2312:2002 covers these and other issues in more detail. The specifier must review these before selecting coatings.

2 CONTENT OF A COATING SPECIFICATION

Before selecting coatings and looking at some individual clauses in a specification, it is necessary to present an overview of the content of a typical coating specification. The following are sections which would normally be present in a typical protective paint specification. There may be other more general sections, such as a list of contractor submittals, requirements for a kick-off meeting, transport arrangements for shop-applied coatings and warranty and guarantee requirements.


1. Scope. This provides a concise but accurate description of the items that will be coated. It should also contain items that will not be coated, such as flange faces, friction grip surfaces, etc. The section may also contain some general clauses.

2. References. This section will provide a list of standards and other documents referred to in the specification. It is normally produced after the document is completed.

3. Definitions and abbreviations. This section contains important definitions and abbreviations that may need clarifying or defining for those outside the coatings industry.

4. Surface preparation. This provides detailed requirements regarding surface preparation requirements for the selected coating system.

5. Coating materials. This lists the coatings used in the selected coating system.

6. Coating application. This provides details of how the coatings should be applied.

7. Inspection requirements. This lists the tests required for surface preparation and coating application and the required records.

3 COATING SYSTEMS FOR STRUCTURAL STEEL

There is an almost infinite number of combinations of primer, intermediate and top coats, along with variations in thickness, pigment types and application properties. Therefore, selecting an optimum coating system is not easy. AS/NZS 2312 has about 70 metallic and paint coating systems for atmospheric exposure, along with 48 additional systems for other environments. A full discussion of all these, let alone the many other systems which may be suggested by suppliers, users or other standards, is clearly not possible. The following sections describe some commonly recommended atmospheric coating systems, and the factors that must be considered if they are selected.

There are many other coating systems in addition to those described below. Some covered in AS/NZS 2312 include:

Metal or thermal spray zinc or aluminium systems. These are selected for very severe environments where long life is required and the high cost can be justified.

Very thick coatings, such as ultra high build epoxy, polyester or vinyl ester. These are generally used for very severe environments such as splash zones or severe chemical exposure. They would not normally be specified for atmospheric environments.

Continuously galvanized or electro-galvanized products that have significantly thinner zinc coatings than that achieved with hot dip galvanizing, and proportionally lower durability. They would normally only be used for mild environments.

Chlorinated rubber coatings have good durability and are easy to maintain, but their high solvent content means they have very limited availability.

The durability of the systems as given in [1] is provided in the discussion. This is the life to first major maintenance, noting that normally some minor touch up will be required before this time. Rather than discussing durability in all environments as given in [1], the life to first maintenance is given only for the ‘C4: High’ corrosivity (AS/NZS 2312 Category D) environment. This environment is found from approximately 0.1 to 1 kilometre inland from a surf beach, such as most sites along the east coast of Australia from the Victorian border to Fraser Island. This includes major centres such as Sydney, Wollongong, Newcastle and the Gold Coast. Such corrosivity is also found on sheltered bays, such as Melbourne or Brisbane right on the coast. Sites further inland will have proportionally greater durability and sites more corrosive will have reduced durability compared to the figures given.

4 HOT DIP GALVANIZING

Zinc metal is perhaps the most important weapon in the fight against corrosion. It corrodes at a much lower rate than steel, often one-twentieth or less, so an intact coating of reasonable thickness will provide good


durability to steelwork except in the most aggressive environments. More importantly, if the coating is damaged exposing steel, the zinc will corrode in preference to the steel, protecting it by cathodic protection. As a result, zinc coatings last a long time and when they do break down, they do not blister or undercut, reducing the need for maintenance.

The single most important coating for protecting steel against corrosion is probably hot dip galvanizing (HDG). This process, coating the steel by dipping in a bath of molten zinc after thorough cleaning, has been successfully protecting steel for over 100 years. It has many advantages over paint coatings. It can provide complete protection to complex shapes, it has excellent adhesion and is highly abrasion resistant. Unlike most paints, edges have good thick coating coverage and no cure time is required. It is process rather than operator controlled, and inspection and quality assurance requirements are normally much simpler. However, it is only a factory-applied process and there is a limit to the size of an item which can be galvanized. The heat of the molten zinc can cause distortion of complex shapes, and vent and drain holes may be required. Along with other zinc coatings, they are only available in grey colour and are not suitable in acidic environments. The rough finish is unlikely to be acceptable in architectural applications, and touch up and repair will always be visible and usually of reduced durability.

A big advantage to the specifier with HDG is the ease of specification. A comprehensive Australian standard [4] is available and a simple sentence on a drawing along the lines of

‘Hot dip galvanize the item to AS/NZS 4680’

is often sufficient. This standard covers surface preparation, galvanizing and inspection, and these do not have to be separately specified. However, note that the quality of the finish permitted in AS/NZS 4680 is pretty ordinary (for example, bare spots up to 40 square centimetres area are permitted) and architectural finishes will require details of the required finish.

The durability of HDG in various corrosivity zones is given in Table 5.2 of AS/NZS 2312:2002, summarised for the C4 environment in Table 2. The HDG industry usually designates coating thickness in terms of grams per square metre rather than microns (100 grams per square metre is 14 microns). The galvanizer has little control over zinc thickness. Specifiers cannot request a zinc coating thickness. Thickness depends mainly on steel section thickness (the thicker the section, the longer it takes to heat up resulting in a thicker coating). The other important variable is the silicon content of the steel. A silicon content of around 0.2% gives a bright, but thin coating while silicon contents less than or greater than this give a dull grey, thicker coating. Different batches of the same grade of steel can vary in silicon content giving different appearance and, more importantly, different zinc thicknesses. If a thicker than normal galvanized coating is required, the specifier should communicate requirements to the galvanizer. Longer residence times and abrasive blast cleaning, at additional cost, may be required if the section thickness and silicon content are not adequate.

Table 2: Hot dip galvanizing systems

System Average coating thickness (µm)

Article thickness (mm)

AS/NZS 2312 C4 durability (years)

HDG390 55 1.5 to 3 5 – 15 HDG500 70 3 to 6 10 – 25 HDG600 85 > 6 15 – 25 HDG900 125 >6, high Si, etc 25+

AS/NZS 2312 lists a number painted HDG systems, so called duplex systems, showing very good durability. Painting the galvanizing provides colour as well as additional durability. While there have been many successful examples of painted galvanizing performing well, there have also been many examples where the paint has severely disbonded from the galvanizing after only a few years. Surface treatments needed to achieve long-term adhesion appear somewhat arbitrary and painting galvanizing is not worth the risk. Galvanizing alone provides very good durability, but if colour is required paint systems should be specified.


5 INORGANIC ZINC SILICATE SYSTEMS

Inorganic zinc silicate (IZS) is one of the best liquid coatings that can be used to protect steelwork. A relatively thin coating of the order of 70 to 100 microns can provide better protection in severe environments than many organic coating systems two or three times as thick. Like galvanizing, it is hard and tough and provides cathodic protection if damaged. Unlike galvanizing, it can be used on items of any size and applied on site as well as in a shop. It is the only paint coating that can be used for friction grip joints. It can only be applied to properly blast cleaned steel and application and curing can be challenging. Although it is often considered as a competitor, IZS should be considered as a complementary coating system to galvanizing [5]. Inorganic zinc is different from other paint coatings in that, despite initially producing a porous film, it continues to harden and cure over time, and it becomes denser and more protective.

There are two main types of inorganic zincs, water-borne and solvent-borne. The water-borne is harder and faster drying, but must be applied under dry, windy conditions. The solvent-borne must have a certain minimum humidity to cure, but is a little more forgiving in application. The water-borne is considered to have slightly better durability, but selection should really be on prevailing environmental conditions. Generally, water-borne would be selected for application under dry conditions, the solvent-borne under more humid conditions. AS/NZS 2312 has three IZS systems: IZS1 is a solvent-borne system applied to 75 microns, IZS2 and IZS3 are water-borne. AS 4848.1 [6] covers surface preparation and application of a solvent-borne system to a minimum thickness of 100 microns, slightly higher than IZS1 so with durability probably closer to IZS2. These systems are listed in Table 3, although the durability of the solvent-borne system is rather conservative. As with hot dip galvanizing, application of a single coat of solvent-borne inorganic zinc can be specified by a single sentence such as:

‘Apply a single coat of solvent-borne inorganic zinc according to AS 4848.1’

Again, this covers surface preparation and inspection so these do not have to be separately specified. Although the standard requires the product to meet the requirements of AS 3750.15 Type 4 which covers properties such as minimum zinc content, acceptable proprietary products would normally be listed. Some coating suppliers provide cheaper, low zinc products which are acceptable for interior and mild environments, but should be avoided in marine environments.

Table 3: Inorganic zinc silicate coating systems

System Surface preparation

Coating AS/NZS 2312 C4 durability (years)

IZS1 Sa2½ 75 µm solvent-borne IZS 5 – 10 IZS2 Sa2½ 75 µm water-borne IZS 15 – 25 IZS3 Sa2½ 125 µm water-borne IZS 25+

AS 4848.1 Sa2½ 100 µm solvent-borne IZS –

6 COLOUR (POLYURETHANE) COATING SYSTEMS

Where colour is required, the most widely specified systems include a top coat of polyurethane, designated PUR in AS/NZS 2312. Polyurethane provides excellent gloss, colour and durability. Mid coats are based on epoxies which also have excellent durability, adhesion and toughness, but chalk, so normally require topcoating. Primers can be zinc-rich, either epoxy zinc or inorganic zinc, or zinc-free epoxy. There are a number of possible systems, depending on environment, required durability, whether it is maintenance or new work and whether there are restrictions on blasting or spraying. For most new work, PUR4 consisting of 75 microns of zinc-rich primer, 125 microns of epoxy mid coat and 50 microns polyurethane top coat, is a widely-specified system, ideal for most environments. Variations to this system are shown in Figure 1, indicating the sort of decisions that the specifier must make.


PUR2Sa2½

75 Epoxy primer 50 PU

PUR2a* Sa2½

75 Zinc primer 50 PU

PUR1 St2

125 Epoxy mastic 50 PU

PUR4 Sa2½

75 Zinc primer 125 HB epoxy

50 PU

PUR6 St 2

75 Epoxy mastic 75 HB epoxy

75 HB PU

PUR5 Sa2½


50 PU

PUR7 Sa2½


75 HB PU

PUR3 Sa2½

75 Epoxy primer 125 HB epoxy

50 PU

Lower cost, Two coat

Maintain Can’t blast Two coat No zinc

Maintain Can’t blast, Can’t spray

No zinc

Higher cost & durability No zinc

Can’t spray

No zincLower costTwo coat

Notes: (1) PU = polyurethane

(2) HB = High build (3) Numbers indicate nominal thickness in microns (4) * PUR2a is not listed in AS/NZS 2312

Figure 1: Relationship between polyurethane topcoat systems in AS/NZS 2312

Looking at the stages in the various systems:

Surface preparation and priming: For most new work, the surface would be blast cleaned to AS 1627.4 [7] Class Sa2½ with a zinc-rich primer. Either inorganic zinc or epoxy zinc could be specified, but recent findings indicate that, in a multi-coat system, there is little difference between performance of epoxy zincs and inorganic zincs. As epoxies are easier to apply and top coat, and do not have curing limitations of inorganic zincs, they would normally be recommended. If use of zinc is restricted, such as in some refineries or if the environment is acidic, a zinc-free epoxy primer would be specified, again to 75 microns. Such primers may contain zinc phosphate inhibitive pigment or no corrosion resistant pigments. If blast cleaning cannot be carried out, hand or power tool cleaning to ISO 8501-1 [8] St2 is specified. Epoxy mastic is normally applied to a minimum dry film thickness of 125 microns if applied by spray, 75 microns if brush application is required (primers should not be applied by roller). Epoxy mastic would also be the primer specified for spot repair, even if spot preparation can be carried out by blast cleaning, as it is likely to be compatible with existing weathered coatings.

Mid or intermediate coats: A mid coat is normally applied to build up thickness and ensure good coverage. Three coats will always provide better protection than two as there is better coverage of critical areas such as edges and corners. A mid coat of 125 microns of standard epoxy is normally sufficient, although this can be increased to 200 microns for very severe environments. If spraying cannot be used, the mid coat would be specified to 75 microns. A mid coat is not required in less severe environments, for shorter life or to reduce costs.


Top coats: A thin top coat of polyurethane is applied to provide colour and gloss retention as epoxies exposed to atmospheric environments tend to chalk. The top coat is normally specified as 50 microns, but for some colours a second coat is required for opacity. Where spraying is not possible, high build polyurethanes which can be applied up to 75 microns by brush or roller are preferred.

Table 4 lists the polyurethane systems and gives relative durability of each. Generally, for best durability, blasting rather than hand or power tool cleaning should be used and three coat systems are better than two coat systems. Although not indicated by the durability figures, zinc-rich primers provide far better protection to edges and damaged areas and should be specified wherever possible in atmospheric applications.

Table 4: Polyurethane topcoat systems

Ref No. Surface prepara-

ation

First coat Second coat Third coat Total thickness

(µm)

C4 Durability

(years) Sa2½ 75 µm zinc primer 200 µm high build epoxy 50 µm polyurethane 325 15 – 25 PUR5 Excellent durability, colour and gloss. Requires blasting and spray application. Sa2½ 75 µm zinc primer 125 µm high build epoxy 50 µm polyurethane 250 10 – 15 PUR4 Very good durability, colour and gloss. Requires blasting and spray application. Sa2½ 75 µm epoxy primer 125 µm high build epoxy 50 µm polyurethane 250 10 – 15 PUR3 Non zinc primer for acidic conditions, or restrictions on zinc. Requires blasting and spray application. Sa2½ 75 µm zinc primer 75 µm HB epoxy 75 µm HB polyurethane 225 5 – 10 PUR7 Similar to PUR4 but for brush/ roller application. For new work or where full removal of existing coating is required. St2 75 µm spot epoxy

mastic 75 µm HB epoxy 75 µm HB polyurethane 225 2 – 5 PUR6

For repair of above systems. Brush or roller application. Mid coat could be epoxy mastic. Sa2½ 75 µm zinc primer 50 µm polyurethane 125 – PUR2a* Lower durability version of PUR4. *Not listed in AS/NZS 2312 Sa2½ 75 µm epoxy primer 50 µm polyurethane 125 5 – 10 PUR2 Lower durability version of PUR3. St2 125 µm epoxy mastic 50 µm polyurethane 175 2 – 5 PUR1 For repair of above systems, no blasting but spraying allowed.

7 ALTERNATIVE COLOUR COATING SYSTEMS

Polyurethane top coat systems are widely specified and used, and have shown excellent performance over many years. One problem with polyurethane is that, during application, free isocyanate in the curing agent is a hazardous material, and painters must be careful to minimise exposure. There is no free isocyanate in cured product and such coatings have no known hazard once the coating is cured. The industry is well aware of the OH&S issues and with proper ventilation and the correct use of personal protective equipment, such coatings can be safely applied. However, health concerns have led to a desire for safer coatings.

Catalysed or two-pack acrylics were introduced in the 1980s as an alternative isocyanate-free coating and became popular in Australia. However, their long term performance has been disappointing, showing reduced durability and greater chalking than the polyurethane equivalents. Furthermore, they are difficult to apply with problems such as very fast drying (although slow curing) and issues with intercoat adhesion. Most of the polyurethane systems described above have catalysed acrylic equivalents in AS/NZS 2312 (the ACC systems) but there is little reason to consider them.

The latest top coat technology is the polysiloxane coating, which appears to have even better durability and gloss retention than polyurethanes. However, as a new coating, they do not have the long-term experience of the polyurethanes and are more expensive. AS/NZS 2312 only lists one polysiloxane system, noting its reduced durability because of limited practical experience. It is a two coat system with a polysiloxane top coat of 125 microns over 75 microns of zinc rich primer. However, coating suppliers now recommend that this product simply replace polyurethane as a 50 or 75 micron coating in a system such as PUR4 or PUR5.


Accelerated testing suggests such systems should give better durability and gloss retention than the polyurethane equivalents.

AS/NZS 2312 also lists single pack alkyd (ALK) and water-borne acrylic latex (ACL) systems. These are easy to apply, relatively cheap and come in a wide range of colours. However, their durability is considerably reduced compared with the above systems, and they are rarely specified for structural steelwork except in mild environments. A single coat of alkyd primer (ALK1) may be all that is required for internal steel beams which are never exposed to the weather. One system which does have good durability is a single coat of acrylic latex over 75 microns of water-based inorganic zinc silicate over a blast cleaned surface (ACL2). ACL2 does require 2 coats, but one is usually sufficient unless colour has poor opacity. Note this system has lower durability than 75 microns of water-based inorganic zinc by itself (IZS2). The top coat is purely for decorative purposes and actually inhibits the long term protection that can be achieved by uncoated inorganic zincs. This is a water-based system so can meet the low Volatile Organic Compound (VOC) requirements of ‘Green Star’ buildings without compromising durability. However, it can be difficult to apply and requires low humidity and windy conditions for proper curing.

Although epoxies chalk and discolour with exposure to UV, they can be used without a top coat, or indeed as a top coat where colour and gloss retention are not critical. They have ease of application, ease of maintenance and good economy as well as good durability. High build epoxies applied up to 200 microns or more over 75 microns of zinc-rich (EHB4) or zinc-free primer (EHB3) over blast cleaned steel can provide an economic coating system with good durability. The ultimate epoxy atmospheric systems use micaceous iron oxide (MIO) pigment in the top or intermediate coat or both. This flaky pigment adds to moisture resistance, provides additional protection against UV light and gives a lustrous metallic finish, at additional cost. EHB6 is a two-coat MIO epoxy systems with very good durability. It should be stressed that, even where gloss, appearance and colour retention are not critical requirements, polyurethane systems are often specified as they hold less dirt, are easier to clean and do not lose thickness from chalking.

The AS/NZS 2312 systems covered in this section are summarised in Table 5.

Table 5: Other Recommended AS/NZS 2312 Colour Paint Systems

Ref No. Surface prepar-

ation

First coat Second coat Third coat Total thickness

(µm)

C4 Durability

(years) St2 40 µm alkyd primer 40 NR ALK1 Simple system for use in a non corrosive environment. Sa2½ 75 µm WB IZS primer 40 µm acrylic latex 40 µm acrylic latex 155 5 – 10 ALC2 Water based system with reasonable durability. Requires blasting and spraying. Sa2½ 75 µm epoxy primer or

zinc primer 200 µm high build epoxy 275 10 – 15 EHB3

EHB4 High durability, two coat system where appearance not critical. Requires blasting and spraying. Sa2½ 75 µm zinc primer 125 µm epoxy MIO 125 µm epoxy MIO 325 10 – 25 EHB6 Very high durability system where a MIO finish is acceptable. Requires blasting and spraying.

Notes: (1) NR = Not recommended (2) WB IZS = Water-borne inorganic zinc silicate.

8 SURFACE PREPARATION

Selection of the optimum coating system is crucial, but the specification must make the surface preparation requirements clear, especially when blast cleaning is required. A typical specification clause for blast cleaning is along the lines of:

‘The surface shall be blast cleaned with steel grit or garnet to AS 1627 Part 4 Class Sa2½ with an angular profile between 40 microns and 75 microns, as measured by replica tape (Method A in AS/NZS 3894 Part 5).’


Such a clause covers two main requirements: the visual cleanliness and the surface profile (or anchor pattern). Issues of concern to the specifier include:

Blast cleaning for atmospheric work is normally specified to Class Sa2½, sometimes called “near white”. This is almost completely clean but a few stains of adherent contamination are allowed. These do not interfere with coating adhesion or durability. A completely clean surface (Class Sa3 or white metal) is normally only required for critical applications such as tank or pipeline linings, underground or underwater structures or similar environments. A lesser standard of cleaning, Class Sa2 leaves quite a bit of contamination and may be suitable for mild environments and less exacting coatings. The manufacturer’s data sheet will give cleanliness requirements, but Class Sa2½ should be specified, even if Sa2 is permitted. However, never specify a lesser standard than permitted by the manufacturer. ISO 8501-1 also contains descriptions of the classes of blast and is sometimes used in specifications.

The clause limits abrasives to steel grit or garnet. Steel grit is only used in shops where it is cleaned and recycled. Garnet can be used in the field as well as in shops. There are a number of other abrasives available, but some, such as some slag, have environmental and OH&S issues as they may contain heavy metals. Sand as an abrasive was banned in Australia many years ago as it can cause silicosis, but is still used in many other countries. Garnet and steel grit are both effective, low dust abrasives and will provide a clean, rough surface with minimal environmental impact.

Surface profile is a measure of the height of the peaks to the valleys of the blasted surface. A profile range, very roughly related to coating thickness is required for most heavy duty coatings. The profile must be jagged or angular for optimum adhesion, and rounded profile produced by shot is not normally acceptable. If not given in the data sheet, Table 6 shows typical profiles for atmospheric coating systems. There are a number of methods for measuring profile, but replica tape is most accurate and the only method that provides a hard copy for QA purposes. Profile is not related to cleanliness, but is not specified for lesser cleanliness grades such as hand or power tool cleaned surfaces.

Table 6: Typical profile requirements for different primer coating types

Primer coating type Nominal DFT (microns)

Recommended profile (microns)

Epoxy (zinc) primer 75 to 100 30 – 50 Inorganic Zinc 75 to 125 30 – 50 High Build Epoxy 150 to 250 50 – 75

Limits on non visible contamination, such as salts, are sometimes specified. However, this is normally only required for maintenance work in severe environments where salt contamination has been a problem. It is not normally required for new work. There are conflicts in the industry over acceptable levels, methods of test and the effect of subsequent coatings. Section 4.2.6 of [1] provides a summary of some of the issues.

Clauses on removal of oil, grease and related contamination, removal of fabrication defects, removal of dust after blasting and the time limit between blasting and priming will also require specification.

9 APPLICATION, INSPECTION AND QUALITY ASSURANCE

The best coating system is wasted if it is not properly applied. Most of the high durability coating systems described above must be carefully applied by skilled applicators to properly prepared surfaces. In some ways, surface preparation and application are more critical than the coatings used. A full discussion of items requiring specification is outside the scope of this paper, but three important aspects will be reviewed.

‘Storage, handling, mixing, thinning and application of all materials shall be in accordance with the manufacturer’s recommendations. All coatings shall be used prior to expiration of shelf life, and catalysed coatings shall be used prior to expiration of pot life.’


A clause such as this means that you do not have to specify all these requirements. The manufacturer’s technical data sheet (TDS) then becomes part of the specification. You may wish to override some TDS requirements, for example you may require that the paint is sprayed for good finish, whereas the data sheet may allow any method of application. Data sheets rarely specify the requirement for stripe coats on edges, welds and other critical regions. They may not include all temperature and humidity restrictions that are desirable. However, a clause such as this is normally a mandatory part of any coating specification.

‘Preference shall be given to contractors who are registered with the Painting Contractor’s Certification Program (PCCP).’

Good quality coating contractors are essential for any coating work, but making sure such contractors are selected is not easy. Good contractors will have trained workers, well-maintained equipment, good QA processes and satisfied customers, among many other qualities. Checking on these is not easy. The Painting Contractor Certification Program (PCCP) [9] is a scheme that accredits contractors who can demonstrate that they can meet certain minimum performance requirements. There are five classes of certification. Classes 1 to 4 cover application of coatings of increasing complexity in a shop or on site. Class 5 covers removal of hazardous material such as lead paint, and such certification is normally mandatory for such work.

‘No surface preparation or coating application shall take place if the relative humidity is greater than 85%, the surface temperature less than three degrees above the dew point or under other unfavourable weather conditions, unless the work is well protected from such conditions. In addition,

the coating shall not be applied if the ambient temperature is below 10° C or surface temperature above 45° C.’

Temperature, humidity and dew point must be monitored and controlled during surface preparation and coating application. A freshly blasted surface may rust if exposed to high humidity or dew point conditions. A freshly painted surface will more often than not be damaged by the same conditions. In addition, most paints will dry too slowly or too quickly if applied at temperatures which are too low or too high. Restrictions such as these would normally be included in most specifications. The manufacturer’s data sheet should give this information and Table 8.1 in [1] provides useful information.

10 CONCLUSIONS

Structural steel will usually require a protective coating system if it is to provide years of good service. This paper has provided:

Some of the factors that must be considered when selecting a protective coating system Some recommended coating systems from AS/NZS 2312 Some typical clauses from a protective coating specification.

Following such advice should enable steel structures to remain corrosion-free for many years.

11 REFERENCES

[1] Standards Australia/Standards New Zealand, AS/NZS 2312:2002, ‘Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings’.

[2] Francis, R.A. 1996, ‘An update on the corrosion process and protection of structural steelwork’, Steel Construction, vol. 30, no. 3, pp. 2-11.

[3] Standards Australia, AS 4312—2008, ‘Atmospheric corrosivity zones in Australia’.

[4] Standards Australia/Standards New Zealand, AS/NZS 4680:2006, ‘Hot-dip galvanized (zinc) coatings on fabricated ferrous articles’.

[5] Francis, R.A. 1998, ‘Inorganic zinc or galvanizing: Choosing the ideal corrosion protection for structural steel’, Steel Construction, vol. 32, no. 3, pp. 2-10.


[6] Standards Australia, AS 4848.1—2006, ‘Application specifications for coating systems, Part 1: Single coat inorganic (ethyl) zinc silicate—Solvent-borne’.

[7] Standards Australia, AS 1627.4—2005, ‘Metal finishing—Preparation and pretreatment of surfaces—Abrasive blast cleaning of steel’.

[8] International Standards Organization, ISO 8501-1:2007, ‘Preparation of steel substrates before application of paints and related products—Visual assessment of surface cleanliness—Part 1: Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous coatings’.

[9] http://www.apas.gov.au/pccp/

22 STEEL CONSTRUCTION VOLUME 45 NUMBER 1 - DECEMBER 2011

ASI STEEL DETAILER MEMBERS

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VICTORIABalpara Pty LtdUnit 8, 104-106 Ferntree Gully RoadOakleigh VIC 3166 03 9544 3877Engineering Design Resource68 Hotham StreetTraralgon VIC 3844 03 5173 7600Fabcad DraftingSuite 359 Church StreetMorwell VIC 3840 03 5133 0733G.A.M. Steel557 Mount Derrimut RoadDerrimut VIC 3030 03 8368 1555Hybrid Steel Engineering48 Wilson RoadMelton VIC 3338 03 9746 9193

PlanIT Design GroupUnit 2A14-16 Garden BoulevardDingley VIC 3172 08 9551 6666

WESTERN AUSTRALIACADstruction DraftingSuite 4, First Floor896 Albany HighwayEast Victoria Park WA 6101 08 9472 7457Formation Design SystemsSuite B, 1A Pakenham StreetFremantle WA 6160 08 9335 1522Multiplan Drafting Pty LtdUnit 12, 4 Queen StreetBentley WA 6102 08 9356 5993PDC Global Pty Ltd48 Kishorn Road Applecross WA 6153 08 9315 6600Universal Drafting Pty LtdSuite 2, 8 Hasler RoadOsborne Park WA 6017 08 9242 8944Westplan DraftingUnit 3/11 Robinson RoadRockingham WA 6168 08 9592 2499

NEW ZEALANDSteel Pencil554 Main StreetPalmerston North 4410 +64 6 356 8253

ASI STEEL MANUFACTURER, DISTRIBUTOR AND GALVANIZER MEMBERS

APC Groupwww.apcgroup.com.auAtlas Steelwww.atlassteels.com.auAus Steelwww.aussteel.net.auAustralian Reinforcing Company (ARC)www.arcreo.com.auBisalloy Steelswww.bisalloy.com.auBlueScope Steelwww.bluescopesteel.comBlueScope Distributionwww.bluescopedistribution.com.auBlueScope Lysaghtwww.bluescopesteel.comBrice Metalswww.brice.com.auCMC Coil Steelswww.cmcaustralia.com.auCommandowww.commando.com.auDematic www.dematic.com/apacDexion Australiawww.dexion.com.auDonhadwww.donhad.com.auFerrocutwww.ferrocut.com.au

Fielders Steel Roofi ngwww.fi elders.com.auFletcher Buildingwww.fl etcherbuilding.comFletcher Insulation Groupwww.tasmaninsulation.comFletcher Challenge Steel - Bisalloy+64 9 525 9414GB Galvanizing Servicewww.gbgalv.com.auGraham Group (NSW) www.grahamgroup.com.auHartway Galvanizerswww.hartway.com.auHoran Steel www.horan.com.auIndustrial Galvanizing Corporationwww.ingal.com.auIngal EPSwww.ingaleps.com.auIntercast and Forgewww.intercast.com.auKingfi eld Galvanisingwww.kingfi eldgalvanizing.com.auKingspan Insulated Panelswww.kingspan.com.auKorvest Galvaniserswww.korvest.com.auLitesteel Technologieswww.onesteel.com/litesteelMacrackwww.macrack.com.auMantamesh/ Delta Shelvingwww.mantamesh.com.auMenghello Galvanizingwww.meneghello.comMetalandwww.metaland.com.auMetalcorp Steelwww.metalcorpsteel.com.auMidalia Steelwww.midaliasteel.comMolnar Engineeringwww.molnarhoists.com.au National Galvanizing Industries Pty Ltdwww.natgalv.com.auOneSteel Australian Tube Millswww.austubemills.comOneSteel Limitedwww.onesteel.comOneSteel Market Millswww.onesteel.comOrrcon Pty Ltdwww.orrcon.com.auPacifi c Steel Groupwww.pacifi csteel.co.nzPremier Steel www.onesteel.comRigby Joneswww.rigbyjones.com.auRondo Building Serviceswww.rondo.com.au

STEEL CONSTRUCTION VOLUME 45 NUMBER 1 - DECEMBER 2011 23

Southern Queensland Steel www.sqsteel.com.auSouthern Sheet & Coilwww.southernsheetandcoil.com.auSouthern Steel Groupwww.southernsteelgroup.com.auSouthern Steel W.Awww.southernsteelwa.com.auSteel & Tube Holdingswww.steelandtube.co.nzSteelpipe Australiawww.steelpipe.com.auStramit Building Products www.stramit.com.auSurdex Steel Pty Ltdwww.surdexsteel.com.auVulcan Steel Pty Ltd03 8792 9600Webforge Australiawww.webforge.com.auWeldlok Industrialwww.weldlok.com.au

Combell Steelfab Pty Ltd51 Jedda RoadPrestons NSW 2170 02 9607 3822Coolamon Steelworks81 Wade StreetCoolamon NSW 2701 02 6927 4000Cooma Steel Co. Pty LtdRoyal HillCooma NSW 2630 02 6452 1934Cosme-Australia Stainless Steel Fab19 Lasscock RoadGriffi th NSW 2680 02 6964 1155Cullen Steel Fabrications26 Williamson RoadIngleburn NSW 2565 02 9605 4888D D’s Engineering and FabricationLot 59 Industrial DriveMoree NSW 2400 02 6752 6274D.A.M. Structural Steel65 Hartley RoadSmeaton Grange NSW 2567 02 4647 7481D.M.E. Kermac Welding & EngineeringCemetery StreetGoulburn NSW 2580 02 9725 5720Davebilt Industries116 Showground RoadNorth Gosford NSW 2250 02 4325 7381Designed Building Systems144 Sackville StreetFairfi eld NSW 2165 02 9727 0566Edcon Steel Pty LtdUnit 3A, 9-13 Winbourne RoadBrookvale NSW 2100 02 9938 8505Ficogi Engineering Pty Ltd33 Liverpool StreetIngleburn NSW 2565 02 9829 2711Flame-Cut Pty Ltd68 Elizabeth StreetWetherill Park NSW 2164 02 9609 3677Fyshwick Metalwork9 Lorn RoadQueanbeyan NSW 2620 02 6299 0294H F Hand Constructors Pty Ltd26-32 Akubra PlaceSouth Kempsey NSW 2440 1300 434 263Halley and Mellowes10 Hereford StreetBerkeley Vale NSW 2261 02 4389 6191Hutchins Bros25-27 Driscoll RoadNarrandera NSW 2700 02 6959 2699ILB Steel Buildings24-28 Lords PlaceOrange NSW 2800 02 6362 3100Industrial Building Systems9 Old Punt RoadTomago NSW 2322 02 4961 6822Mecha Design & FabricationPO Box 477Wyong NSW 2259 02 4351 1877Morson Engineering4 Lucca RoadWyong NSW 2259 02 4352 2188National Engineering Pty Ltd288 Boorowa StreetYoung NSW 2594 02 6382 9372

Nepean Engineering23 Graham Hill RoadNarellan NSW 2567 02 4646 1511Pacifi c Steel Constructions Pty LtdUnit 1, 4 Maxim PlaceSt Marys NSW 2760 02 9623 5247Piper & Harvey Steel Fabrications (Wagga) Pty Ltd51 Tasman RoadWagga Wagga NSW 2650 02 6922 7527Precision Oxycut106 Long StreetSmithfi eld NSW 2164 02 9316 9933Rambler Welding Industries Pty Ltd39 Lewington Street NSW 2650 02 6921 3062Riton Engineering Pty Ltd101 Gavenlock Road NSW 2259 02 4353 1688S&L Steel Fabrications59 Glendenning RoadRooty Hill NSW 2766 02 9832 3488Saunders International Ltd271 Edgar StreetCondell Park NSW 2200 02 9792 2444Sebastian Engineering Pty Ltd21-25 Kialba RoadCampbelltown NSW 2560 02 4626 6066Sydney Maintenance Services2/16 Carnegie PlaceBlacktown NSW 2148 0412 083 704Tenze Engineering55 Christen RoadPunchbowl NSW 2196 02 9758 2677Tubular Steel Manufacturing Pty Ltd15 Johnson StreetMaitland NSW 2320 02 4932 8089Universal Steel Construction (Australia) Pty Ltd52-54 Newton RoadWetherill Park NSW 2164 02 9756 2555Walpett Engineering Pty Ltd52 Hincksman StreetQueanbeyan NSW 2620 02 6297 1277Weldcraft Engineering (ACT) Pty Ltd79 Thuralilly StreetQueanbeyan NSW 2620 02 6297 1453WGE Pty Ltd29 Glastonbury AveUnanderra NSW 2526 02 4272 2200

NORTHERN TERRITORYM & J Welding and Engineering1708 Mckinnon RoadBerrimah NT 801 08 8932 2641

QUEENSLANDAG Rigging & Steel207-217 McDougall StreetToowoomba QLD 4350 07 4633 0244Alltype Welding55 Christensen RoadStapylton QLD 4207 07 3807 1820Austin Engineering173 Cobalt StreetCarole Park QLD 4300 07 3271 2622Austweld Engineering77 Coleyville RoadMutdapilly QLD 4307 07 5467 1122

ASI STEEL FABRICATOR MEMBERS

AUSTRALIAN CAPITAL TERRITORYBaxter Engineering Pty Ltd177 Gladstone StreetFyshwick ACT 2609 02 6280 5688

NEW SOUTH WALESAWI Steel Pty Ltd36 Day StreetNorth Silverwater NSW 2128 02 9748 6730Aardvark Steel Constructions16A Jumal PlaceSmithfi eld NSW 2164 02 9632 2411Algon Steel7 Pippita CloseBeresfi eld NSW 2322 02 4966 8224Align HLot 102 Lackey RoadMoss Vale NSW 2577 02 4869 1594Allthread Industries15 Bellona AvenueRegents Park NSW 2143 02 9645 1122Amarcon Group23 Arizona RoadCharmhaven NSW 2263 02 4352 2468Armidale Romac Engineering288 -290 Mann StreetArmidale NSW 2350 02 6772 3407Beltor Engineering Pty LtdThe BroadwayKillingworth NSW 2285 02 4953 2444Bosmac Pty Ltd64-68 Station StreetParkes NSW 2870 02 6862 3699C & V Engineering Services Pty Ltd23 Church AvenueMascot NSW 2020 02 9667 3933Charles Heath Industries18 Britton StreetSmithfi eld NSW 2164 02 9609 6000

24 STEEL CONSTRUCTION VOLUME 45 NUMBER 1 - DECEMBER 2011

Beenleigh Steel Fabrications Pty Ltd41 Magnesium DriveCrestmead QLD 4132 07 3803 6033Belconnen Steel Pty Ltd11 Belconnen CrescentBrendale QLD 4500 07 3881 3090Bettabuilt Fabrication685 Kingsthorpe-Haden RoadKingsthorpe QLD 4400 07 4634 4355Brown Steel157 O’Mara RoadCharlton QLD 4350 07 4614 3901Cairns Steel Fabricators6 Walters StreetPortsmith QLD 4870 07 4035 1506Casa Engineering (Brisbane) Pty Ltd1-7 Argon StreetCarole Park QLD 4300 07 3271 2300Central Engineering Pty Ltd19 Traders WayCurrumbin QLD 4223 07 5534 3155Durable Engineering460 Beaudesert RoadSalisbury QLD 4107 07 3277 7007DWW Engineering Pty Ltd53 Station AvenueDarra QLD 4076 07 3375 5841Fritz Steel (QLD) Pty Limited29 Enterprise StreetRichlands QLD 4077 07 3375 6366Gay Constructions Pty Ltd225 Queensport RoadMurrarrie QLD 4172 07 3890 9500KG Fabrication Pty LtdUnit 3/35 Sodium StreetNarangba QLD 4504 07 3888 4646Morton Steel Pty Ltd78 Freight StreetLytton QLD 4178 07 3396 5322Noosa Engineering & Crane Hire9 Leoally RoadNoosaville QLD 4566 07 5449 7477Pierce Engineering Pty Ltd48 Quinn StreetNorth Rockhampton QLD 4701 07 4927 5422Quality Assured Bolt & Steel Fabrication44 Andrew Campbell DriveNarangba QLD 4504 07 3888 3888Rimco Building Systems Pty Ltd3 Supply CourtArundel QLD 4214 07 5594 7322Steel Fabrications Australia Pty Ltd58 Anton RoadHemmant QLD 4174 07 3439 6126Steel Structures Australia26-28 Link DriveYatala QLD 4207 07 3287 1433Stewart & Sons Steel11-17 Production StreetBundaberg QLD 4670 07 4152 6311Structural Steel Buildings592 Ingham RoadMount Louisa QLD 4814 07 4774 4882

Sun Engineering113 Cobalt StreetCarole Park QLD 4300 07 3271 2988Thomas Steel Fabrication19 Hartley StreetGarbutt QLD 4812 07 4775 1266Watkins Steel106 Depot StreetBanyo QLD 4014 07 3414 7400W D T Engineers124 Ingram RoadAcacia Ridge QLD 4110 07 3345 4000

SOUTH AUSTRALIAAdvanced Steel Fabrications61-63 Kapara RoadGillman SA 5013 08 8447 7100Ahrens GroupWilliam StreetSheaoak Log SA 5371 08 8524 9045BGI Building Group21-23 Tanunda RoadNuriootpa SA 5355 08 8562 2799Bowhill EngineeringLot 100, Weber RoadBowhill SA 5238 08 8570 4208Gadaleta Steel Fabrication12 Wattle StreetPort Pine SA 5540 08 8633 0996Manuele Engineers16 Drury TerraceClovelly Park SA 5042 08 8374 1680RC & ML Johnson 671 Magill RoadMagill SA 5072 08 8333 0188S A Structural9-11 Playford CresentSalisbury North SA 5108 08 8285 5111S J Cheesman21 George StreetPort Pirie SA 5540 08 8632 1044Samaras Structural Engineers96-106 Grand TrunkwayGillman SA 5013 08 8447 7088Steriline Racing38 Oborn RoadMt Barker SA 5251 08 8398 3133Tali Engineering119 Bedford StreetGillman SA 5013 08 8240 4711Williams Metal Fabrication181 Philip HighwayElizabeth South SA 5112 08 8287 6489

TASMANIAHaywards Steel Fabrication & Construction160 Hobart RoadLaunceston TAS 7249 03 6391 8508

VICTORIAAlfasi Steel Constructions73-79 Waterview CloseDandenong South VIC 3175 03 9794 9274Apex Welding & Steel Fabrication15 Centofanti PlaceThomastown VIC 3074 03 9466 4125

Aus Iron Industries15-17 Galli CourtDandenong South VIC 3175 03 9799 9922Australian Rollforming Manufacturers35-45 Frankston - Dandenong RoadDandenong VIC 3175 03 9794 2411Bahcon Steel Pty Ltd549 Princes DriveMorwell VIC 3840 03 5134 2877Geelong Fabrications Pty Ltd5-17 Madden AvenueGeelong VIC 3214 03 5275 7255GFC Industries Pty Ltd42 Glenbarry RoadCampbellfi eld VIC 3061 03 9357 9900GVP Fabrications Pty Ltd25-35 Japaddy StreetMordialloc VIC 3195 03 9587 2172Kiewa Valley Engineering Pty Ltd34 Moloney Drive Wodonga VIC 3690 02 6056 6271Martin Jones Welding & Mechanical Services120 Roses LaneClunes VIC 3370 03 5345 3969Materials Fabrication/ Melbourne Facades5/23 Bell StreetPreston VIC 3072 03 480 0054Metalform Structures Pty Ltd2 Zilla CourtDandenong VIC 3175 03 9792 4666Minos Structural Engineering Pty LtdBulding 3, 69 Dalton RoadThomastown VIC 3074 03 9465 8665Monks-Harper Fabrications Pty Ltd25 Tatterson RoadDandenong South VIC 3164 03 9794 0888Multicoat Pty Ltd7 Laser DriveRowville VIC 3178 03 9764 8188Page Steel Fabrications Pty Ltd20 Fulton DriveDerrimut VIC 3030 03 9931 1600Riband Steel (Wangaratta) Pty Ltd69-81 Garden RoadClayton VIC 3168 03 9547 9144Skrobar Engineering Pty Ltd12-14 Sullivan StreetMoorabbin VIC 3189 03 9555 4556Stilcon Holdings Pty Ltd37 Link CourtBrooklyn VIC 3012 03 9314 1611Structural Challenge Pty Ltd63 Star CrescentHallam VIC 3803 03 8795 7111Thornton Engineering Australia Pty Ltd370 Bacchus Marsh RoadCorio VIC 3214 03 5274 3180Wolter Steel Co. Pty Ltd12 Elite WayCarrum Downs VIC 3201 03 9775 1983

WESTERN AUSTRALIAAllstruct Engineering16 Ryelane StreetMaddington WA 6109 08 9459 3823Alltype Engineering Services52 Hope Valley RoadNaval Base WA 6165 08 9410 5333Arch Engineering9 Rivers StreetBibra Lake WA 6163 08 9418 5088AGCLevel 2, 251 St Georges TerracePerth WA 6000 08 6210 4518Austline Fabrications181 Welshpool RoadWelshpool WA 6106 08 9451 7300Bossong Engineering Pty Ltd189 Planet StreetWelshpool WA 6106 08 9212 2345Cays Engineering17 Thornborough RoadGreenfi elds WA 6210 08 9582 6611Civmec Construction and Engineering Pty Ltd16 Nautical DriveHenderson WA 6166 08 9437 6288

Complete Steel Projects31 Cooper RoadJandakot WA 6164 08 9414 8579EMICOLFirst Floor, Ascot PlaceBelmont WA 6104 08 9374 1142Fitti Steel Fabrication11 Erceg RoadYangebup WA 6965 08 9434 1675Fremantle Steel Fabrication Co.Lot 600 Prinsep RoadJandakot WA 6164 08 9417 9111GF Engineering39 Lionel StreetNaval Base WA 6165 08 9410 1615Highline Limited8 Colin Jamieson DriveWelshpool WA 6106 08 6454 4000Holtfreters Pty Ltd1 Centro AvenueSubiaco WA 6008 08 9442 3333H’var Steel Services Pty Ltd51 Jessie Lee StreetHenderson WA 6166 08 9236 2600Inter-Steel Pty Ltd9 Ilda RoadCanning Vale WA 6155 08 9256 3311

Italsteel W.A.1 Forge StreetWelshpool WA 6106 08 6254 9800Metro Lintels2 Kalmia RoadBibra Lake WA 6163 08 9434 1160Pacifi c Industrial Company42 Hope Valley RoadNaval Base WA 6165 08 9410 2566Park Engineers Pty Ltd388 Welshpool RoadWelshpool WA 6106 08 9451 7255Perna Engineering32 Cocos DriveBibra Lake WA 6163 08 9418 6352R&R Engineering (WA) Pty Ltd1021 Abernethy RoadForestfi eld WA 6058 08 9454 6522Scenna Constructions43 Spencer StreetJandakot WA 6164 08 9417 4447United Group ResourcesPO Box 219Kwinana WA 6167 08 9219 5500Uniweld Structural Co Pty Ltd10 Malcolm Road Maddington WA 6109 08 9493 4411

Level 13, 99 Mount Street, North Sydney, NSW 2060 Phone (02) 9931 6666 Facsimile (02) 9931 6633 Email [email protected] Website steel.org.au

Documents

Specifying Steel Corrosion Protection