White Rust Coating

8/6/2019 White Rust Coating

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NOVEMBER 2006Vol. 13 No 2

Registered by Australia Post

PP No. 229640/00002

White Rust on Zinc Coatings - Causes, Effects & Remedies

Duplex Coating Ensures Long Pipe Bridge Life

Commodities & Coating Costs


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INTERNATIONAL STRENGTH IN

GALVANIZING AND MANUFACTURING

Industrial Galvanizers Corporation operates

a network of galvanizing and manufacturingfacilities throughout Australia, Asia and the USA.

In Australia, these operations include:

INGAL Hot Dip Galvanizing

INGAL EPS steel pole engineering and

manufacturing

INGAL Civil Products steel highway safety

products

INGAL Building Systems - Lintels, T-beams

Webforge - Grating, handrails

Auszinc Alloys - Zinc alloys and chemicals

GALVANIZING

AUSTRALIA www.in ustria ga vanizers.com.au

Queensland

Industrial Galvanizers (Brisbane)

Ph: 07 3000 7900 Fax: 07 3260 2244

In ustria Ga vanizers De ta

P : 07 3271 268 Fax: 07 3271 2295

Industrial Galvanizers (North Qld)

Ph: 07 4774 8333 Fax: 07 4774 8444

New South Wales

In ustria Ga vanizers Newcast e

P : 02 4967 9099 Fax: 02 4964 8705

In ustria Ga vanizers Sy ney

Ph: 02 9636 8244 Fax: 02 9631 8615

Industrial Galvanizers (Kirrawee)

Ph: 02 9667 4328 Fax: 02 9693 2104

Industrial Galvanizers (Port Kembla)

P : 02 4275 2755 Fax: 02 4276 1277

Victoria

Industrial Galvanizers (Melbourne)

P : 03 9480 2866 Fax: 03 9484 7144

Tasmania

Industrial Galvanizers (Tasmania)

Ph: 03 6344 8822 Fax: 03 6344 7691

Western Australia

In ustria Ga vanizers WA

Ph: 08 9418 2122 Fax: 08 9434 1377

United States of America www.indgalv.net

Asia www.in ustria ga vanizers.com

MANUFACTURING

INGAL CIVIL PRODUCTS www.inga civi .com.au

Head Office Ingal Civil Products

P : 02 9710 5555 Fax: 02 9542 3667

Brisbane

Ph: 07 3271 3369 Fax: 07 3271 3299

Newcastle

Ph: 02 4964 8206 Fax: 02 4964 8705

Me ourne

P : 03 8470 0082 Fax: 03 9480 1834

Pert

Ph: 08 9451 4100 Fax: 08 9451 4200

EBFORGE www.webforge.com.au

Hea O ce

P : 03 8551 2456 Fax: 03 8551 2454

New South Wales

Ph: 02 9997 8555 Fax: 02 9997 7546

Queensland

Ph: 07 3260 1064 Fax: 07 3260 1130

Victoria

P : 03 9551 1911 Fax: 03 9558 0730

Western Austra ia

Ph: 08 9361 8933 Fax: 08 9361 7057

New Zealand

Ph: 001164 6356 1246 Fax: 01164 6356 7782

INGAL EPS www.inga eps.com.au

Western Australia

Ph: 08 9493 9222 Fax: 08 9493 9234

Queens an

P : 07 3323 2555 Fax: 07 3344 5422

Victoria

Ph: 03 9793 3670 Fax: 03 9701 3907

New South Wales

Ph: 02 9545 5199 Fax: 02 9545 0276

South Australia

P : 0500 533 833 Fax: 08 8345 1740

Austra ian Capita Territory

Ph: 02 6247 4555 Fax: 02 6247 4777

Tasmania

Ph: 03 6273 0577 Fax: 03 6273 0575Northern Territory

P : 08 8947 0870 Fax: 08 8947 0764

ww.in ga v.com.au

Industrial Galvanizers Corporation Pty Ltd, 1585 Ipswich Rd, Rocklea 4106 Australia, Ph: 07 3373 2875 Fax: 07 3373 2827


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CONTENTS

EDITORIAL

FEATURE ARTICLES

Duplex Coating Ensures Long Pipe Bridge Life

Commodities & Coating Costs

Why Do Coatings Fail?

White Rust on Zinc Coatings - Causes, Effects & Remedies

INDUSTRY NEWSPreserving Metal Masterpieces

Cathodic Protection of Steel in Concrete with Zinc Metal Spray

New Era For Dy-Mark Aerosols

New Website Resource for Galvanized Coatings

Suite of Revised Galvanized Coating Standards

Molded Fiberglass Companies FRP Pile Repair Sleeves Extend Timber Pile Life

Munters Preventing Coating Failures

CORROSION MANAGEMENT

PUBLISHER:Industrial Galvanizers Corporation Pty Ltd.

EDITOR:

John Robinson312 Pacific HighwayHexham NSW 2322

Ph: +61 2 4967 9088

Fax: +61 2 4964 8341

Email: [email protected]

DESIGN:

MAP MarketingVilla Franca, 2 Scott Street

Newcastle NSW 2300

P : +61 2 4929 7766Fax: +61 2 4929 7827


ww.mapmarketing.com.au

ADVERTISING:

MAP MarketingVilla Franca, 2 Scott Street

Newcastle NSW 2300

P : +61 2 4929 7766Fax: +61 2 4929 7827


www.mapmarketing.com.au

CORROSION MANAGEMENT is published by Industrial Galvanizers Corporation, which operates internationally

through a network of galvanizing and manufacturing plants. Industrial Galvanizers Corporation is involved in the

application of protective coatings for industrial, mining, domestic and commercial projects, using the best availabletechnology and is not affiliated with any specific suppliers of corrosion or abrasion resistant coatings.

The opinions expressed herein are not necessarily those of the publisher.

CORROSION MANAGEMENT is published for those interested in the specification, application and performance of

protective coating systems.

In Australia (Newcastle Harbour NSW), old timber piles are in the process of being removed from this

deteriorated wharf - Page 26.

Cover:

Andy Scott Stallion

on the Beach.

contents

2

5

8

5

9

21

23

23

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26

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4/32 N O V E M B E R 2 0 0 62

The main theme of this issue of Corrosion Management

reflects the dark side of protective coatings, with a feature

on why coatings fail (both organic and metallic), and a

major technical article on causes, problems and solutionsassociated with white rust and zinc coatings.

Understanding why coatings fail is as important as

understanding why they work. In a number of cases in which

I have been involved in the consulting side of my business,

apparently adequate anti-corrosion specifications have not

worked, giving rise to very costly litigation, as well as equally

costly remediation.

These costs are dramatically disproportionate to the original

cost of the coatings used. In two separate instances, the cost

of the coatings used was less than $3,000 on each project,while the remediation costs, excluding legal costs, exceeds

$150,000 in each case.

White rust problems have become a particular headache

in our global economy, as larger numbers of galvanized

products are shipped around the world. Galvanized products

that are in good condition when they are dispatched from

the galvanizing plant, may have been severely degraded

by white rust by the time they reach their destination after

being containerised and crossing the equator.

Another significant issue facing the suppliers of protectivecoatings and corrosion resistant materials has been the

unprecedented increase in costs of both metals and

petroleum products over the past 2 years.

Metals such as zinc, the principal anti-corrosion solution

for the majority of the words steel, is a good example

of skyrocketing costs. In the past year, zinc prices have

increased by 180% and do not look like heading south anyime soon.

In this issue, Corrosion Management has gathered

information from suppliers of protective coating products,

galvanizers and the stainless steel industry to put these cost

rises into perspective so that end-users can understand their

impact in ensuring the durability of construction products.

In delivering certified coatings to the market place, suppliers

and specifiers rely on Australian or international standards

o provide guidance in ensuring a quality outcome. As

Corrosion Management goes to press, a suite of revisedgalvanized coating standards has just been published by

Standards Australia and we are pleased to be able to preview

hese standards in this issue.

From January 2007, recent issues of Corrosion Management

ill be published on the Industrial Galvanizers Web Site.

More information on the comprehensively upgraded web

site can be found in the Industry News section of this issue.

editorial

John Robinson - Editor


5/323

featurearticle

DUPLEX COATING ENSURES

LONG PIPE BRIDGE LIFE

Two cranes (300t and 200t) were used to lift the 40t bridge section into place. The duplex coating is expected to provide more than 50 years

maintenance free service life in this environment.

I N T R O D U C T I O N

A significant structural bridging project was recently

undertaken by the NSW Department of Commerce (now

incorporating the NSW Public Works Department), to design

a pipe bridge for Sydney Water to cross Mallaty Creek, on

private property near Appin, NSW.

To eliminate the need to access private property for

maintenance, the DOC specified a duplex (paint over hot dip

galvanizing) protective coating for the large prefabricated

bridge structure.

T H E P R O J E C T

The Mallaty Creek bridge was prefabricated by JBK

Engineering (Unanderra, NSW) for the DOC. The pipe bridge

as designed to carry a 1200 mm steel cement lined water

main across the creek. The bridge structure is substantial,

being 38 metres long, 4.5 metres wide and 3.5 metres high,

ith a total weight of 40 tonnes.

The heavy construction was required to carry the design

loads of over 1000 kg/metre that are imposed by the

operating water main.

The bridge was assembled in two sections at JBKs

Unanderra workshop; the sections transported to site and

fully assembled, then lifted into position using a 300 tonne

and a 200 tonne crane.


6/32 N O V E M B E R 2 0 0 64

The fabrication and coating application was supervised

by DOCs Frank Barnes, one of the departments most

experienced inspectors with many years experience in

this area, including participation of the construction of the

Sydney 2000 Olympic venues.

T H E P R O T E C T I V EC O A T I N G S Y S T E M

All the steelwork was hot dip galvanized by Industrial

Galvanizers, either at its Port Kembla facility for the smaller

components, or at its larger (12.5 metre) bath at Girraween,

in Sydney.

The galvanized coating was specified to comply with

Australian Standard AS/NZS 4680:1999. Coating thickness

of the hot dip galvanized coating as was found to generally

exceed the minimum thickness nominated in the Standard

by at least 30%. The recommended surface preparation

procedure is also listed in Appendix I of AS/NZS 4680.

This states:

INFORMATION ON THE USE OF SWEEP (BRUSH) BLAST

CLEANING OF GALVANIZED STEEL PRIOR TO PAINTING

(Informative)

I1 GENERALAbrasive sweep (brush) blast cleaning is a method

used for the preparation of a galvanized coating prior to the

application of an organic (paint) coating. The purpose of this

procedure is to remove the oxide film from the zinc surface.

NOTE: It is important that this procedure be performed carefully

to ensure that no more than 10 pm of zinc is removed.

Organic paint coatings should be applied as soon as possible

after galvanizing or abrasive blasting.

I2 PROCEDUREThe following procedure should be observed

when sweep blast cleaning is carried out to ensure that a good

surface is produced for painting, without severely damaging the

existing galvanized coating:

(a) Use fine abrasives of a size which will pass through a test

ieve of nominal aperture size 150 pm to 180 pm (80 to 100

esh), e.g. ilmenite or garnet

(b) Use a venturi nozzle which has an orifice diameter of 10m to 13 mm

(c) Set the blast pressure at 275 kPa (40 psi) maximum

(d) Keep the venturi nozzle at a distance of 350 mm to 400

m from the surface of the work piece and at an angle no

greater than 45 to the surface

This procedure is intended to produce a light surface profile

of 5-10 microns.

Dulux paint system was applied over the hot dip

galvanized surfaces. The system was as follows:

Primer Coat - Dulux Luxepoxy 4 white primer to 50-70

microns DFT

Second Coat - Dulux Luxathane R to 50-75 microns DFT

Top Coat - Dulux Luxathane R to 50-75 microns DTT

Total minimum DFT system thickness was specified at 225microns.

The surface preparation and system application was

undertaken by Waldeans Industrial Painters at Port Kembla,

and through careful handling of the bridge section in

ransport and erection, no additional coating remediation

as needed on site.

C O N C L U S I O N

The duplex coating system used on the Mallaty Creek pipe

bridge should ensure that the structure will remain corrosionfree for a period exceeding 50 years. The combination of

high quality paint systems over hot dip galvanizing has

a synergistic effect in producing a coating system whose

performance will exceed that of the sum of each of the

coatings if they were used independently. A factor of an

additional 50% has been suggested.

Mallaty Creek Bridge, trial assembled in JBK Engineerings Unanderra

workshop.


7/325


Over the past 18 months, the commodity boom has been in

the news almost every day. For most Australians, it is goodnews in that unemployment is at record low levels and the

economy is in a very healthy condition.

At street level, we have all been affected by oil price rises and

their impact on fuel costs, many commodities have doubled

or tripled in cost over this relatively short period, and do not

look like their cost will be heading south in the near future.

One largely hidden impact of these commodity cost

increases is the impact on the cost of protective coatings for

steel, the full impact of which is yet to be felt.

In addition to the rapid cost increases in some of the

major ingredients used in protective coating manufacture,

particularly zinc and petroleum, corrosion resistant

materials such as stainless steel and brass have been

similarly impacted by commodity cost increases of its major

constituents.

Z I N C & G A L V A N I Z I N G

inc is the primary anti-corrosion component for protecting

steel in its various forms, and is used for electroplating,

continuous galvanizing of wire, sheet and tube and for the

hot dip galvanizing of structural steel.

World zinc usage exceeds 9 million tonnes, of which nearly

half is used for galvanizing, and around 20% is used for

alloying with brass or bronze. Nearly 10% is used for the

manufacture of zinc chemicals, a significant proportion of

hich are used as pigments in paints.

featurearticle

COMMODITIES &

COATING COSTSJohn Robinson Editor Corrosion Management

Commodity prices affect everyone. This galvanizing plant in Virginia USA, has experienced the same cost impacts for its zinc as have Australian

galvanizers.


8/32 N O V E M B E R 2 0 0 66

Since the beginning of 2005, zinc has increased in cost

from around $US1,450/tonne to over $US4,000/tonne in

November 2006 an increase of almost 200%. In Australia,

the zinc price is also influenced by the $A exchange rate

with the $US. At an average exchange rate of $0.76, the cost

increases in $A from January 2005 to November 2006 have

been from $A2,000 to $A5,400.

The biggest impact has been on galvanizing costs. Theamount of zinc used in a galvanizing process will be

determined by the thickness of the steel (this determines its

surface area), the zinc (galvanized) coating thickness and the

type of process (this determines the residues generated by

the process).

The average zinc usage for general (jobbing) galvanizing

ranges from 6% of the weight of steel dipped for structural

fabrications, to 10% for smaller parts that are galvanized in a

centrifuge process.

The chart illustrates the cost impact of the zinc cost increasesfor these types of products.

inc cost/t - $A Fabrications - 6%inc Pick-up

Small Parts - 10%Zinc Pick-up

$2000 $120 $200

$5400 $324 $540

Increase $204 $340

The other costs associated with the hot dip galvanizing

process include energy, labour, materials, overheads and

margins. In normal times these make up typically 75% of thecosts, with zinc being the remaining 25%.

For project tonnages of structural steel, a competitive cost

for hot dip galvanizing, with zinc at $2,000/tonne, would be

in the order of $550/tonne. This same steelwork would need

to be galvanized for $754/tonne to recover the additional

zinc costs.

A typical cost for small part (centrifuge) galvanizing in

contract quantities would be in the order of $850/tonne at

the $2,000/t zinc price. $1,190/t small part galvanizing prices

are now required to recover the increased zinc coat.

P A I N T C O S T S

The biggest impact on industrial paint costs has again

been in the zinc component used in high-performance

organic and inorganic zinc-rich primers. Zinc dust is sold at a

premium to ingot zinc. This premium is in the order of

$US700, and accounts for the manufacturing costs

associated with zinc dust production.

This has pushed current $A zinc dust prices beyond

$6,000/t. Although the metallic zinc content of a zinc-richpant coating is about half that of a galvanized coating, the

cost impact remains significant.

In addition to the zinc dust cost for zinc-rich primers, zinc is

also a major component of zinc phosphate pigments used in

almost all solvent-based steel primers. These types of primers

have around 50% volume solids in the paint and while only

some of pigment components are zinc-containing, there is

an inevitable cost impact.

The other major factor influencing industrial paint costs is

he rise in the oil price, which has essentially doubled since2004, from around $US30 per barrel to the current cost of

around $US60/barrel.

The ingredients used in most industrial paints are largely

from petrochemical sources, which obviously have a direct

connection to oil price movements.

While the cost of a barrel of oil is listed on the news every

night, few people know how this relates to litres or gallons.

The attached chart shows the common conversion factors

for petroleum.

Table 1

Convert From onvert To Multiply By

Barrel (Petroleum) Cubic Metre 0.158910

Cubic Metre Barrel (Petroleum) .292

Barrel (Petroleum) U.S. Gallon 42.0

U.S. Gallon Barrel (Petroleum) 0.02381

Barrel (Petroleum) Litre 58.910

Litre Barrel (Petroleum) 0.006292

U.S. Gallon Litre .785

Imperial Gallon Litre 4.546

Litre U.S. Gallon 0.2642

Drum Litre 205

There are 42 US gallons in a barrel of oil, or nearly 159 litres.

This equates to $0.38 per litre. Given that numerous refining

and processing stages are necessary to convert a litre of oil

o a litre of epoxy, polyurethane, acrylic or solvent, the oil

cost impact is less significant than that of the cost of the

pigments used.

C O R R O S I O N R E S I S T A N T

M A T E R I A L S

The metals most commonly used on anti-corrosion

applications are stainless steel (Iron, nickel, chrome alloy),

brass (copper-zinc alloy), bronze (copper-tin alloy) and

aluminium.

While there have been increases in the cost of chrome,

in and aluminium, they have been at levels normally

experienced in the metals commodity area in times of high

demand of around 20-70%.

Copper, nickel and zinc prices, on the other hand havegone into another territory all together. Table 2 shows the

approximate price movements of these metals from early

2005 to late 2006.


9/327

Table 2

Metal Early 2005

cost $A

Late 2006

cost $A

Increase

$A

change

Aluminium $2,100 $3,550 $1,450 69%

Chromium $7,900 $12,100 $4,200 53%

Copper $4,000 $10,000 $6,000 50%

Nickel $18,500 $44,000 $25,500 38%

Tin $10,500 $13,500 $3,000 29%

Zinc $1,800 $5,000 $3,200 78%

The impact on common stainless steel anti-corrosion grades

such as 316 is that the nickel and chrome components that

make up over 25% of the alloy will have increased the cost

(from early 2005) by almost $5,000/tonne by late 2006.

S U M M A R Y

While demand continues to exceed supply for the metals

used for anti-corrosion applications, it is unlikely that therewill be any downward price adjustments to more normal

levels in the foreseeable future.

The lack of investment in new zinc mines and production

facilities and the closure of a number of smelters in the

1990s and early 2000s will put pressure on zinc supply for

some time to come, and this is likely to have the biggest

impact on protective coating costs for steel.

It will be up to suppliers to ensure that the coating processes

bare as efficient as possible to ensure that zinc-based

protective coatings remain competitive in deliveringlong-term anti-corrosion protection for steel.

Stainless steel costs have dramatically increased because of the

significant increase in nickel cost, with manufacturing cost increasing

by over $A5,000 since 2004.

Zinc is used as a component in paints and other industrial chemicals, such as zinc oxide, being manufactured along with zinc dust in this facility.


10/32 N O V E M B E R 2 0 0 68

featurearticle

WHY DO COATINGS FAIL?

Corrosion Management Staff

Paint quality and application standards are critical in military projects such as this maintenance operation on HMS Parramatta at Forgacs

Dockyard in Newcastle, NSW.


11/329


All protective coatings are designed to do a certain job

of protecting steel for a specified time. It is on this basis

that they are chosen by specifiers and end-users. To make

a protective coating decision, the designer has to either

trust the supplier to recommend the correct product, have

personal experience with the performance of the coating

and its application or be knowledgeable about coatingperformance and the environment to which the protective

coating will be exposed.

All protective coatings will fail eventually. It is their job to

sacrifice themselves to protect what is underneath. When

coatings fail prematurely, the costs of remediation are

frequently out of all proportion to their initial cost of supply

ad application.

There are many reasons why coatings fail. Some are

predictable and some are not that easily identified. In most

cases, however, the reasons for premature coating failure arelargely human rather than technical. This article has been

prepared to provide information about the mechanisms

of coating failure for both paint and metallic (galvanized)

coatings.

G A L V A N I Z E D C O A T I N G S

All galvanized coatings are applied by some type of factory-

based process that involves the chemical cleaning and

surface preparation of the steel followed by immersion

in molten zinc or a zinc alloy. For this reason galvanized

coatings are never subject to hidden application problemscaused by surface preparation or application because the

coating will not form unless the surface of the steel has been

properly prepared.

Galvanized coatings never fail from underneath because:

They are metallurgically bonded to the steel surface

Zinc is anodic to steel and will prevent steel from

corroding as long as any zinc is present

Contaminants cannot penetrate the metallic coating.

While there are some differences in the various types of zinccoatings, their durability is always determined by the way in

which the galvanized coating reacts to its environment. Like

most protective coatings, galvanized coatings are relatively

thin, ranging from around 15 microns in thickness for the

thinnest coatings on pre-galvanized sheet, wire and tube

products up to 200 microns or more for hot dip galvanized

coatings on structural steel. To put these coating thicknesses

in relative terms, a plastic supermarket bag is about 15

microns thick, a sheet of photocopy paper is about 100

microns thick and a business card is about 250 microns in

thickness.

Metallic coatings fail through progressive oxidation of

heir surfaces. The metallic components of the coating;

inc and zinc-iron alloys in the case of galvanized coatings,

are consumed by exposure to oxidation or dissolution by

chemicals and/or the action of atmospheric moisture. Over

50 years of laboratory and field experience with galvanized

coatings has determined that:

The corrosion rate of galvanized coatings isapproximately linear

The coating life is largely determined by the coating

thickness

The coating mass (g/m) is important in providing

cathodic protection to exposed steel

The failure of a galvanized coating will thus be determined

by the rate at which the coating is consumed. This rate

of consumption will vary depending on the exposure

conditions. A large amount of performance data that has

been accumulated on zinc coatings allows the parameters

causing failure to be accurately defined. These are:

. pH Levels: Zinc is an amphoteric metal that will react with

either acids or alkalis. Galvanized coatings perform poorly in

low pH (acid) exposure when pH drops much below pH6. At

low pH levels, very rapid dissolution of the zinc will occur. At

alkaline pH levels up to about pH 10, galvanized coating will

provide adequate performance.

2. Time of Wetness (TOW):The TOW is an important factor

in the failure of galvanized coatings. Zinc is a reactive

metal and like aluminium, requires the presence of stable

complex carbonate oxide film on the surface (visible as the

characteristic grey colour of weathered galvanizing) to give

he coating its durability. Where galvanized surfaces are

constantly wet, particularly with a moving moisture film,

he stable oxide films have difficulty in forming or may be

washed off, with re-oxidation of the surface accelerating the

consumption of the coating.

3. Presence of Chlorides & Sulfates: Chlorides and sulfates

ill react with the zinc surface to form soluble zinc salts and

ill prevent the formation of the carbonate films. Galvanized

coatings exposed in marine splash environments perform

poorly for this reason.

. Contact with Cathodic Metals: Zinc is high on the

Electrochemical Series of metals. It will dissolve sacrificially

hen in contact with metals lower in the Series. This

property is used on pre-galvanized sheet, wire and tube

products to prevent corrosion of the steel exposed at cut

edges during processing. The thicker the section, the more

stress is placed on the zinc coating at the interface and its

corrosion rate is accelerated in order to provide cathodic

protection to the exposed steel. When galvanized coatings

are in contact with large areas of metals such as stainless

steel or copper, rapid dissolution of the galvanized coating

can occur.


12/32


13/321 1

I M P R O P E R D E S I G N

Improper design includes selecting the wrong material

for the location and conditions and requiring an improper

installation. The following design problems can lead to

organic finishes failure:

. Selecting materials of inappropriate composition.

2. Selecting incompatible system components.3. Selecting organic materials that are incompatible with

he substrates, including existing finishes.

. Requiring or permitting use of materials with different

VOC type or quantity than that of existing paint without

proper preparation.

5. Improper preparation or application methods.

. Insufficient dry film thickness (not enough coats).

I M P R O P E R P R E P A R A T I O N

1. Failing to remove mildew, moss, ivy, and other plant

growth, efflorescence, laitance, oil, grease, dirt, dust, rustcorrosion, loose mill scale, wax, calcimine, loose existing

paint, and other contaminants that interfere with proper

application, or damage or telegraph through the finish

material.

2. Failing to remove sources of moisture and water that

affect the finish and to ensure that the substrate is

completely dry. Water and moisture can cause a finish to

dry slowly, aiding mildew, moss, and other plant growth.

3. Failing to neutralize alkali in masonry substrates or use

alkali-resistant paints can cause peeling. Alkali residue

can cause a paints gloss to be poor or inconsistent.

4. Failing to remove natural salts from previously paintedsurfaces results in peeling and under-film corrosion.

5. Failing to remove loose, peeling, or otherwise unsound

nish materials from an existing surface before applying

a new finish.

6. Applying finish materials over a slick or glossy surface.

ailing to remove gloss from an existing surface or

undercoat before applying a succeeding coat results in

ailure of the finish to adhere.

7. Failing to prime water-stained surfaces before painting.

8. Failing to remove chalking before repainting.

9. Failing to remove rusted nails, other fasteners and other

rusted items or to clean the rust off and apply a rust-

inhibitive primer.

0. Failing to countersink nails and screws, fill the holes, and

spot prime.

1. Failing to remove discolorations caused by colour

extractives in wood substrates and provide a stain-

blocking primer.

2. Failing to clean and apply a knot primer to knots that are

already bleeding or may bleed in the future.

3. Failing to sand shoulders at the edges of sound paint or

otherwise feather the edges of existing paint where new

paint is applied.

4. Failing to properly prepare wood substrates, including

removing residue from knots, pitch streaks, cracks, open

joints, and sappy spots; applying a coat of white shellac

to pitch and resinous sap wood before the prime coat is

applied.

5. Failing to properly prepare metal substrates.

6. Failing to fill holes and imperfections in the substrate.

I M P R O P E R A P P L I C A T I O N

1. Failing to follow the design and recommendations of

the manufacturer and recognized authorities.

2. Applying organic finishes before the building has been

completely closed and wet work, such as concrete,

masonry, and plaster, have dried sufficiently. or where

concrete or plaster is not at the proper level of alkalinity.

3. Applying paint to damp or wet surfaces can cause poor

adhesion and blistering.

4. Applying finish materials when humidity exceeds the

level recommended by the manufacturer.

5. Applying primer or finish material at temperatures

below the minimum specified by the manufacturer. Low

temperatures can cause wrinkling and prevent adhesion.

This steel lintel coating has failed after only 3 years. Probable cause is poor surface preparation and a costly repair.


14/32 N O V E M B E R 2 0 0 61 2

6. Applying organic finishes when the temperature of the

air, surface, or finish is too high. High temperature can

hin the finish material and make it cover poorly, set too

rapidly, and form too thin a film. Surfaces, or air that is too

hot can also cause a paint to wrinkle or the paint not to

adhere.

7. Permitting drastic changes in temperature before a paint

has completely set can result in alligatoring or checking

when the paint expands or contracts. If the top coat is

not elastic enough, it will crack.

8. Permitting a wide temperature differential between the

finish and the surface, which may cause blistering and

peeling.

9. Failing to remove dust, dirt, moisture, and other

contaminants between coats, causing blisters, peeling,

cracking, flaking, or scaling.

10. Failing to ensure that the surfaces of previous coats are

conditioned before the next coat is applied.

11. Using the wrong type finish for the installation.

12. Applying organic finish materials that are incompatible

with previous coats, existing finish materials, or

substrates.13. Applying damaged organic finish materials, regardless of

whether the damage was inherent in the manufactured

materials or occurred during shipment, storage, or

installation.

14. Using the wrong primer.

15. Using the wrong, defective, or poor-quality thinner.

Such solvents may evaporate too quickly. resulting in

wrinkling, alligatoring, blistering, checking, peeling,

flaking, cracking, or checking. Or they may dry slowly,

causing the finish to dry too slowly or never dry

completely.

16. Using too little thinner, resulting in orange peeling,flaking, cracking, or scaling.

17. Using too much thinner. Failing to properly agitate

and mix paint before and during application can cause

colour separation, resulting in alligatoring, checking,

peeling, flaking, cracking, or scaling. Improperly mixed

paint may not dry.

18. Mixing incompatible paints.

19. Adding lamp black or another pigment material to paint

materials to make them hide better with less paint.

20. Adding too much oil to paint, causing alligatoring or

checking and improper drying.

21. Using pigments incompatible with other ingredients,

resulting in alligatoring. checking, peeling. flaking.

cracking, or scaling.

22. Failing to properly apply paint or transparent finish

materials, including not using enough material.

23. Failing to apply a uniform paint film.

24. Applying finish coats that are too thin.

25. Applying finish coats that are too thick..

26. Applying a coat of organic finish to a still wet undercoat,

causing the finish to dry slowly or wrinkle.

27. Applying a hard finish coat over a relatively soft

undercoat can cause wrinkling, alligatoring, checking, or

peeling of the top coat.

28. Permitting water in the air line used in solvent basedpaint spray applications.

29. Applying sprayed paint using too high an air pressure,

causing wrinkling.

30. Applying paint using incompatible spray equipment

- incorrect mixing, nozzle pressure, nozzle size.

P O O R M A I N T E N A N C E

P R O C E D U R E S

1. Failing to clean finishes regularly. Grease, dirt, and other

contaminants can result in permanent stains.

2. Cleaning using abrasive or caustic cleaners can severelydamage organic finishes.

3. Failing to keep vegetation from growing on or close

to building surfaces. Vines can penetrate the surface,

permitting water to enter. Mildew and moss can grow on

the wet surfaces. Water can force efflorescence from the

substrate, causing paint to peel or flake off.

4. Water in a wood substrate can set up a chemical reaction

between the water and the natural extractives in the

wood, staining the paint.

N A T U R A L A G I N G

Organic finishes lose their properties over time for the

following reasons:

1. Failure to refinish at proper intervals. Finish materials

exposed to the suns UV rays fail faster than those in other

locations. All organic finishes fail eventually and need to

be maintained and repainted at proper intervals.

This paint failure was caused by applying the solvent-based paint

over a damp surface, causing subsequent blistering.


15/321 3

2. Bleeding of natural finished wood. Unprotected wood

exposed to weather turns dark over time as water-soluble

impurities bleed out. The appearance of bleeding on

ransparent-finished exterior wood surfaces indicates

hat the finish has failed and water has reached the

substrate. The worst woods for bleeding are redwood and

cedar.

3. Mildew growth due to a failed finish permitting water to

reach the substrate.

4. Loss of elasticity. Old paint loses its elasticity and

becomes hard and unable to respond to expansion

and contraction in its substrate. The result is crazing,

alligatoring, flaking, or peeling.

5. Permeability of the paint film. Moisture penetrating paint

lm or entering through cracks or holidays in the steel

surfaces will initiate rusting under the paint film.

6. Natural erosion. Weathering paint slowly wears away

until it eventually does not properly protect thesubstrate.

P R E V E N T I N G F A I L U R E S

Specifiers cannot absolutely control what happens during

construction, but their specifications and what they do

during the construction phase can greatly affect the

outcome.

1 . F o l l o w M a n u f a c t u r e r sR e c o m m e n d a t i o n s

Products that appear similar may have entirely different

preparation and application requirements. A prudent

specifier will call the manufacturers technical representative

for advice. A mistake specifiers often make is failing to verify

hat manufacturers listed in the specifications actually make

products that comply with the specified requirements.

The variety of products is so broad and their chemistry so

beyond the knowledge of most specifiers that it is not wise

o guess at which products are compatible. The only positive

ay to ensure quality is to specify a particular product and

hen enforce its use. Make sure that the products specified

are compatible with existing solvents,finishes and with each

other.

Specifications should require that all components of

a system are the products of the same manufacturer.

Government specifications sometimes present real obstacles

o controlling the quality of finishing products.

n agency may prohibit naming products. More often,

products may be named to establish quality but not to limit

supply to the named products. Beef up the specifications

here the agency will let you do so, to control more closely

finishing products and their application.

Paint manufacturers put a lot of effort into developing their products to determine their performance and subject them to exposure testing in

facilities such as this.


16/32 N O V E M B E R 2 0 0 61 4

2 . W r i t e C o n t r o l s I n t oS p e c i f i c a t i o n s

Contracts that prohibit specifying products and

manufacturers by name will require more submittal data

than projects where the products can be limited. When not

permitted to specify products by name, write descriptive

specifications. Specify requirements that fit within every

acceptable manufacturers recommendations and everyproduct specified. Always require that repair work be done

by the original installer.

3 . S p e c i f y A p p r o p r i a t eP r o d u c t s & S y s t e m s

Apart from specifying paint systems of the appropriate

generic type for the application, it is necessary to be aware

of development on OH&S legislation on the availability of

certain types of paint. Approval of certain types of long

established pigments has been withdrawn (lead, chromates,

coal tar) and other paint system components used in twopack systems are under review (isocyanates). Restrictions

have been placed in volatile organic compounds (VOCs)

or solvents in paints in many jurisdictions and this will

force changes to established painting technology away

from solvent based systems to water based, high solids or

solventless products.

4 . S p e c i f y C o r r e c tP r e p a r a t i o n &A p p l i c a t i o n P r o c e d u r e s

Follow the specific preparation and application proceduresrecommended by the manufacturers of the products

specified. Pay particular attention to the need to ensure that

the surface is not contaminated with invisible contaminants

such as diesel fuel residues (from truck exhausts) or

chlorides. Guide specifications often overlook problems that

can occur when existing finishes are involved. A properly

administered quality assurance plan is required and the

applicator should be certified to an acceptable Australian or

ISO standard.

5 . E n s u r e C o m p l i a n c e

The final thing a specifier can do to avoid potential

organic finish failures is to carefully review the credentials

of both supplier and applicator. Make sure that the

products submitted are right for the job and comply with

specifications. Make sure that the applicator is qualified to

an acceptable quality standard. The cheapest bidder will

rarely have the best application credentials. The person

who handles field observation must enforce the specified

requirements related to preparation for and application of

organic finishes. Ignoring even apparently small faults can

lead to disastrous results.

C O N C L U S I O N

ll coatings will eventually fail and understanding the

reasons for failure will allow the best cost/ performance

compromise to be reached. Quality coatings will rarely

deliver quality performance with second rate application.

Quality coatings will rarely deliver quality performance if

hey are used in an inappropriate application. Every generic

coating type has particular characteristics that will suit itfor specific applications. With rapidly changing technology,

particularly in the areas of industrial paint coatings and

continuous galvanizing, it is becoming increasingly difficult

for specifiers to evaluate the long term performance of

coatings and their reliability as these new coatings have yet

o establish their own set of successes and failures as have

he well established coating technologies.

R E F E R E N C E S

1. ot Dip Galvanizing, 4th Edition. Galvanizers Association

of Australia (1995) pp 25.2. Porter, F.C., Corrosion Resistance of Zinc and Its Alloys,

Marcel Dekker Inc, (1994) pp 83-98.

3. Simmons, H.I, ield Applied Organic Finish Failures, The

Construction Specifier, July 1996 pp 54.

4. Robinson, J.C., Design for Galvanizing Manual, 2nd Edition,

Industrial Galvanizers Corporation, 1996 pp 28-32.

5. Hare, Clive H., aint Film Degradation, SSPC 01-14 (2001)

Part 4 pp 113-407.

All successful paint coatings rely on good surface preparation.


17/321 5

When steel is first galvanized, the zinc coating has not developed its protective oxide film and is most prone to rapid oxidation when in contact

with pure water.

WHITE RUST ON ZINC COATINGS -

CAUSES, EFFECTS & REMEDIESfeaturearticle

John Robinson, Mount Townsend Solutions Pty Ltd


inc is among single most widely used coating materials

used to protect steel from corrosion. It is applied to steel

components by a number of industrial processes. These

include zinc electroplating, the continuous galvanizing of

sheet, wire and hollow sections, and the hot dip galvanizing

of fabricated steel items.

While many of these coating processes use alloying elements

in the zinc (such as aluminium), most products are coated

with largely zinc-based coatings.

problem common to all these products, is the

phenomenon of white rust, or more euphemistically referred

o as white storage stain.

While its mechanism is well understood, its occurrence

presents a major difficulty to both the manufacturers and

he galvanized products end users. This problem arises

because it is often difficult to allocate responsibility for

damage that occurs to galvanized products due to whiterusting as the coating may be in 100% good condition when

it leaves the galvanizing facility.


18/32 N O V E M B E R 2 0 0 61 6

This is a particular difficulty when product is exported or

imported in containers, is stored for an extended period and

transits from temperate to tropical climatic zones.

On delivery, the galvanized coating may be rejected by the

customer because of white rust problems in transit. Who is

responsible?

T H E M E C H A N I S M O F W H I T ER U S T F O R M A T I O N

Zinc is a relatively reactive metal and it will react vigorously

with both acids and alkalis. Its delivers its best anti-corrosion

performance in neutral pH conditions, and is thus well

suited as a protective coating in most atmospheric exposure

classifications, other than severe marine.

However, zinc, like aluminium, relies on the formation of an

oxide film on its surface for its durability. Once this oxide film

is formed, the rate of corrosion of zinc (galvanized) coatings

is very slow typically 2 microns or less in thickness per yearin normal environments.

When steel is freshly galvanized, the zinc has no significant

oxide film on its surface. The chemical reactions that occur to

form this film take some time. They are:

1. The oxidation phase 2Zn + O2 = 2ZnO

2. The hydration phase 2Zn = 2H2O + O = 2Zn(OH)2

3. Carbonation 5Zn(OH)2 = 2CO2 +

2ZnCO .3Zn(OH) + 2H2O

It is the formation of the zinc carbonate oxide film, that is

highly water insoluble, that provides the underlying zinc

with its good anti-corrosion performance.

Other reactions can occur in the presence of chlorides,

sulfates and other corrodents that may accelerate the

degradation of the zinc-based coating at a rapid rate. It is

the exposure of `young zinc-coated surfaces to pure water

that is the principal mechanism associated with white rust

formation.

Pure water (H O) contains no dissolved salts or minerals andzinc will react quickly with pure water to form zinc hydroxide,

a bulky white, and relatively unstable, oxide of zinc. Where

freshly galvanized steel is exposed to pure water (rain, dew

or condensation), in an oxygen deficient environment, the

water will continue to react with the zinc and progressively

consume the coating. The most common condition in which

white rust occurs is where galvanized products are nested

together, tightly packed, or when water can penetrate

between the items and remain for extended periods.

In favourable (for white rust) conditions, very rapid

consumption of the zinc can occur and corrosion rates 20-50times higher than those normally experienced.

While this type of corrosion is called white rust, it may have

a dark gray or even black appearance on the galvanized

surface.

It is standard galvanizing practice in hot dip galvanizing

facilities, to cool the work by quenching it in water. In most

operations, the quench water contains a low concentration

of sodium dichromate (usually less than 0.5%).

The quenching of the hot steel in this weak dichromate

solution creates a passivating film on the galvanized

coatings surface that provides some initial protection for the

inc, and gives to time to develop its own protective oxide

film.

Some proprietary coatings are applied to continuously

galvanized products to perform the same function.

These treatments must be considered temporary. In periods

of heavy rain, the dichromate passivation film, which is

slightly soluble in water, can be washed off the surface andcan increase the propensity of the zinc surface to white rust

hen exposed to pure water.

Short-term exposure to rain water is not necessarily a

problem, and wetting and drying cycles may in fact assist in

he development of the protective oxide film.

Carbon dioxide is required to initiate the development of the

stable carbonate based oxide film, thus good access to air

is an essential part of the process. Poorly ventilated, damp

conditions are conversely very detrimental in white rust

formation.

Heavy white rusting on guard rail assembly caused by water trapped

between nested components.


19/321 7

The galvanized products in the foreground have been passivated with a more concentrated sodium dichromate solution, giving them a slightly

yellow tinge and higher white rust resistance.

A V O I D I N G W H I T E R U S TF O R M A T I O N

There are a number of simple steps that can greatly reduce

or eliminate the formation of white rust. These are:

1. Keep the packed work dry

2. Pack the items to permit air circulation between the

surfaces

3. Stack the packed items at an angle to allow water to

drain out

4.Treat the surface with proprietary water repellent

or barrier coatings to prevent moisture contact with

galvanized surface

5. Provide adequate ventilation when transporting

galvanized items for extended periods

T R E A T I N G G A L V A N I Z E DS U R F A C E S A F F E C T E D B YW H I T E R U S T

Once the galvanized surface has been attacked and the zinc

hydroxide compounds have formed, it is desirable to remove

the oxide products from the surface because:

a.Their presence inhibits the formation of stable carbonate

based oxides

b.They are unsightly

The effect on the galvanized coating can range from veryminor to extremely severe. Various levels of remedial

treatment are available to deal with white rust problems at

the levels at which they are likely to occur.

The following treatments are recommended to deal with

hite rust on galvanized products.

1 . L i g h t W h i t e R u s t i n g

This is characterised by the formation of a light film of whitepowdery residue and frequently occurs on freshly galvanized

products during periods of heavy rain. It is particularly

evident on areas that have been buffed or filed during

quality assurance operations. These treatments remove

he passivated surface from the galvanizing and expose

unoxidised zinc to attack from rainwater. Provided the

items are well ventilated and well drained, white rust rarely

progresses past this superficial stage. It can be brushed off

if required but will generally wash off in service with normal

eathering. No remedial treatment is generally required at

his level.

2 . M o d e r a t e W h i t e R u s t i n g

This is characterised by a noticeable darkening and

apparent etching of the galvanized coating under the

affected area, with the white rust formation appearing

bulky. The galvanized coating thickness should be checked

o determine the extent of attack on the coating. In the

majority of cases, less than 5% of the galvanized coating

ill have been removed and thus no remedial work should

be required, as long as the appearance of the affected

area is not detrimental to the use of the product and the

inc hydroxide residues are removed by wire brushing. Ifappearance is unacceptable, the white rust affected area can

be treated as follows:


20/32 N O V E M B E R 2 0 0 61 8

a. se a wire brush or abrasive pad to remove all white

corrosion products

b. sing a cloth pad wet with aluminium paint, rub the

surface with the pad to apply a thin film of aluminium

paint to the affected area to blend it with the adjacent

unaffected galvanized surfaces.

3 . S e v e r e W h i t e R u s t i n g

This is characterised by very heavy oxide deposits. Items may

be stuck together. Areas under the oxidised area may be

almost black of show signs of red rust. A coating thickness

check will determine the extent to which the galvanized

coating has been damaged. Remedial treatment to reinstate

the coating should be undertaken as follows:

a. ire brush or buff the affected area to remove all

oxidation products and rust if any

b. pply one or two coats of approved epoxy zinc-rich paint

o achieve required dry film thickness of 100 microns

minimum

C H E M I C A L R E M O V A L O FW H I T E R U S T

Pasminco (now Zinifex) has researched the effectiveness of

chemical removal of white rust and reported the results in its

Technical Project Report No. D713C (6th July 1995).

This research report evaluated the effectiveness of several

chemical treatments based on sodium dichromate,

chromium trioxide, sodium hydroxide and chromic acid

respectively.

From this research, two systems were found to be effective

in both removing white rust and re-passivating the cleaned

inc surface.

These combinations were:

1.420 g/l chromium trioxide + 0.5% nitric acid

2. 200 g/l chromic acid

The chromic acid solution proved most effective in

removing white rust residues with minimum effect on

he substrate, while the chromium trioxide/nitric acid

combination was best at reinstating the passivation

properties of the zinc surface.

The removal of white rust by each of these methods needs

o done with due diligence with respect to environmental

constrains and OH&S issues related to handling chemicals

of this type. These processes are also suited to localised

reatment of white rust affected areas.

Where large areas of the products are white rust affected,

re-galvanizing may be the most economical option.

C O N C L U S I O N

White rust is a post-galvanizing phenomenon.

Responsibility for its prevention lies in the manner it

is packed, handled and stored prior to the galvanized

products installation and use. The presence of white rust is

not a reflection on the galvanized coatings performance,

but rather the responsibility of all those involved in the

supply chain to ensure that the causes of white rust arerecognised and the risks of its occurrence minimised on

newly galvanized steel.

Severe white rusting has occurred on the edge of this guard rail. The dark area has had almost all the zinc coating removed in less than 12 weeks

duting storage in damp conditions.


21/321 9

Scottish sculptor and artist Andy Scott has produced metal

masterpieces of public art, initially from his home base

in Glasgow. Australia has also been a recipient of Andy

Scotts skill in the form of four metal sculptures that he has

produced locally.

These works included a woman depicting timeless

elements of the human experience which stands 6 metres

tall with outstretched arms 3.9m, was a centre piece for

the SWELL Currumbin Sculpture Festival 2004 followed up

a life size stallion, which was a centre piece for the SWELLCurrumbin Sculpture Fest 2005.

industrynews

PRESERVING METAL

MASTERPIECES

Corrosion Management Staff

When the ArtsCape sculpture exhibition asked Andy Scott

if he wanted the prime location of the most eastern point of

ustralia to display another of his works of art, how could he

refuse? Argestes (which means the east wind) Aqua is a 5m

high steel mosaic masterpiece of man made from small 3mm

plates of steel individually welded together.

The topography of the Byron Bay headland created logistical

challenges for the installation of the Argestes Aqua. With the

assistance of a local helicopter the sculpture was airlifted in

wo sections to its final display location.

Andy Scott and Lady Sculpture.


22/32 N O V E M B E R 2 0 0 62 0

ndy Scott has continued to wow the artistic world of

sculpting. Recently Andy has been commissioned to public

orks on behalf of the Gold Coast City Council (Lady + Child

Sculpture) and Southport Rotary Club.

Each of these Andy Scott steel sculptures is extremely

complex with myriads of connected steel elements making

up their forms. Providing these metal masterpieces with an

appropriate level of corrosion protect that would also satisfyhe aesthetics and final quality requirements of the artist,

along with the physical size of the sculptures, made hot dip

galvanizing Andy Scotts preferred option.

Each of these sculptors was galvanized in Brisbane by

Industrial Galvanizers Corporation. The larger sculptures

needed to de double-dipped because of their dimensions.

The complete immersion of the sculptures into the molten

inc ensured that all internal surfaces, welds and connections

ere uniformly coated with a heavy zinc-based coating that

is highly abrasion resistant, along with its corrosion resistant

properties.

nother advantage of the hot dip galvanizing process, is that

at some future time, when the coating has reached the end

of its service life, each artwork can be quickly re-galvanized

o reinstate it to its original level of durability.

More information on Andy Scotts wonderful works can be

seen on his website at:

ww.aqza25.dsl.piper.com/andy/work.html

Top Right:

Argesta Aqua at Byron Bay.

Right:

Lady + Child just out of the bath - the Industrial Galvanizers

galvanizing bath in Brisbane, Qld.


23/322 1

CATHODIC PROTECTION OF STEEL INCONCRETE WITH ZINC METAL SPRAY

For many years industrial companies have fought to protect

steel reinforced concrete from corrosion. The prime causes

of corrosion in concrete include salt, chloride and de-icing

treatments. The salt seeps into the concrete and erodes the

steel reinforcing bar (rebar) causing cracks and spalling in

the concrete and eventually the potential for failure of the

structure. One very effective, long-term solution is metal or

thermal spraying the concrete with zinc or a variety of zinc

alloys. This is a technology that protects or extends the life of

a wide variety of products in the most hostile environments.

The majority of metallised zinc cathodic protection systems

are operated in galvanic or sacrificial mode. However,

metallised zinc cathodic protection systems can be, and are

in many instances, operated in impressed current mode. The

sprayed coating, a high purity zinc alloy, is connected to one

pole of a DC power supply. The steel rebars are connected

industrynews

o the other pole of the power supply. The electrical circuit is

completed between the rebar and the zinc by the presence

of moisture in the concrete. The action of the corrosion cell

causes the zinc to corrode in preference to the steel rebars,

herefore protecting the rebars from corrosion.

The process of spraying the zinc onto the substrate ensures

hat there is a good, even connection path between the

coating and the rebars through the concrete. Prior to metal

spraying, damaged sections of concrete need to be repaired

ith rebars also repaired or replaced. The surface needs to

be lightly blasted to remove any surface dirt and provide a

good key to enable the coating to bond. The coating would

hen be applied with either a Metallisation Arc140, Arc701

or Arc170 system, depending on the size and accessibility ofhe structure. Typical bond strength is in the region of 3MPa

for zinc and coating thickness would be between 300 and

500 microns.

Zinc metal sparing onto concrete structures to provide cathodic protection for the reinforcing bar has proved an economical solution on a

number of major projects in Europe and the USA.


24/32 N O V E M B E R 2 0 0 62 2

The costs to apply metal sprayed coatings to large concrete

structures is not insignificant, particularly when many

structures are difficult to access, such as bridges.

However, the long-term benefits can make the process

extremely commercially attractive. If performed correctly

and depending on the coating applied, the process can

offer corrosion protection for up to 20 years before the

next significant maintenance is required. The protectionoffered can greatly prolong the life of the structure and also

prevent costly accidents from cracked sections falling from

the structure. Once applied, the coating requires minimal

maintenance. If required for aesthetic purposes, zinc

coatings can also be painted.

A recently developed alloy of aluminium, zinc and indium

has been used in a small number of applications. This

material is more active than zinc and it is claimed to not

require an impressed current to provide adequate levels of

corrosion protection.

A recent example of corrosion protection using this alloy

has been trialled by Aeroports de Paris at Charles de Gaulle

(Roissy) airport. Aeroports de Paris, responsible for the

maintenance of most of the Roissy airport infrastructure,

recognised deterioration in some of the concrete panels

at the airport and sought a long-term corrosion protection

solution. The precast concrete panels, which are 2.6 x 2.8m

of lightly reinforced 8cm thick units, form the underside of

the concrete viaducts carrying road traffic to and from a busy

terminal complex. Run-off from de-icing salt has lead to an

important level of chloride in the panel concrete. Although

the panels are not structurally significant, spalling could

present a hazard to passing traffic.

Following a stringent review and testing of the panels to

establish the deteriorating condition, an anode was applied

to the panels in a test area. After grit blasting the panel

surface, the anode of aluminium/zinc/indium alloy was

applied by a Metallisation arc spray system to an application

thickness of 300 microns. The anode connection plate in

the centre of each panel is clearly visible by its red anode

cable, which would not normally be on show in a typical

commercial application. The other cables run to connections

to the rebars and to embedded reference electrodes. As

this is a test site it was necessary to install monitoringequipment. This was to allow the connection between the

anode and cathode to be interrupted for measurement of

electrochemical performance. After two years the system

appears to be well adapted to treat corrosion of the viaduct

panels and is deemed to be a successful test.

Another significant application of the Al-Zn-In alloy in the

US is the San Luis Pass Bridge near Galveston, Texas. More

than 30,000 m2 of concrete beams and caps are protected

with this alloy, installed using Metallisation ARC 700 units by

Corrosion Restoration Technologies of Jupiter, Florida.

Oregon Department of Transportation (ODOT) demonstrates

another success story for cathodic protection on concrete.

In a bid to reduce the high costs of bridge reconstruction,

ODOT has applied a system of metallised zinc anodes and

impressed current cathodic protection. This process has

been used to protect its Cape Creek Bridge from corrosion

and subsequent reconstruction. The bridge is exposed to

a coastal environment and is subject to attack by chloride

from the salty air. Prior to the cathodic protection project on

he bridge, it had suffered substantial concrete spalling on its

columns and underdeck. By selecting to protect the bridge

in this way ODOT saved over $13 million by not having to

reconstruct the bridge. The cost of cathodic protection is

quite expensive. This is due to the requirement of a movable

ork platform, which is enclosed to contain the abrasive

blasting and zinc spraying residues. These measures are

critical when spraying zinc to protect the environment.

However, when compared to the cost of reconstructing

a bridge the size of Cape Creek Bridge the savings are

phenomenal.

Dave Wixson, Metallisation distributor in the US says:

Cathodic protection is a cost effective way to stop rebar

corrosion in existing structurally sound structures. Rebars in

dry alkaline concrete are protected by a passive ferric oxidefilm, however, when the rebar is hit with 250 ppm chloride

solution, generally from salt, the protection breaks down.

The protective ferric oxide film is converted to red rust and

corrosion begins. Concrete thickness >4cm (>1.5 in), will

prevent chloride penetration. For exposed rebar and thin

concrete, where there is chloride concentration in excess of

about 250 ppm, rebar corrosion will be initiated with the red

rust spalling adjacent concrete. Protecting the rebar with a

barrier using an impressed or passive cathodic protection

system, counters the corrosion.

Many thanks to Palmer Consulting of France, TMS of the USAand Corrosion Restoration Technologies Inc (now part of

Structural Group, Inc.) of the USA for information supplied.

For more information on thermal spraying please contact

Stuart Milton on +44 (0)1384 252 464 or visit

ww.metallisation.com


25/322 3

NEW ERA FOR DY-MARK

AEROSOLSindustrynews

Australian owned aerosol manufacturer Dy-Mark Coatings

has officially launched its new divisional name, corporate ID

and eight new product lines at launches around Australia.

Dy-Mark Coatings has extensive experience and knowledge

in aerosols, paints and inks and is recognised as one of

the leading suppliers of quality identification products in

Australia.

A two new product range of particular interest is the new

Anti-Slip Industrial paint and Rust Reformer paint Dy-Mark.

Anti-Slip Industrial paints creates a durable slip-resistant

surface for most interior and exterior metal, concrete,

ceramic and wood surfaces. Dy-Mark Anti-Slip aerosols apply

easily and provide uniform coverage with a low-lustre satin

finish. The aerosols dry tough and are resistant to substances

like oil, petrol and mild chemicals, with a durable finish that

resists peeling and cracking.

Dy-Mark Rust Reformer aerosol chemically converts rust into

a tough non-rusting barrier in one easy step which protects

against further corrosion. Ideally suited for metal equipment,

railings and furniture the coating dries to a hard flat black

nish. Aerosol is extremely useful for spraying complex

shapes and other hard to reach areas.

Rust Reformer aerosol can be top coated with compatible

nish products such as alkyd and modified alkyd resin

systems. In addition, the coating can be top coated with a

ater-based product if the reformer is allowed to dry for

24 hours. Dy-Mark Rust Reformer aerosol is available in a350g can.

For further information please

contact:

Sandy Hollows

Group Marketing Manager

Dy-Mark Group

Ph: 07 3723 8083

M: 0424 509 022

[email protected]

NEW WEBSITE RESOURCE FOR

GALVANIZED COATINGS

An upgraded website will be launched in December2006 by Industrial Galvanizers Corporations Australian

Galvanizing Division to enhance its value as a resource for

specifiers seeking information and services associated with

the specification, use and availability of hot dip galvanized

coatings.

The new Ingal website is designed for easy information access

and incorporates a number of new features. These include:

The complete Ingal Specifiers Manual - 40 chapters of

echnical information on all aspects of hot dip galvanized

coatings and other industrial coating systems. The Ingal/CSIRO Corrosion Mapping System - corrosivity

maps for anywhere in Australia.

Recent and previous issues of Corrosion ManagementMagazine - online.

Galvanizing plant locations and capacities.

Online quote requests.

Special services - Galvanized Coating Guarantees and

Custom Coating Packages.

Case studies - Case histories of the performance of hot dip

galvanized coatings on major projects.

Online technical inquiry service.

The majority of technical and reference information on the site

is designed to be downloadable in PDF format should hard

copy be required.

The website address is www.ingal.com.au


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industrynews

SUITE OF REVISED GALVANIZED

COATING STANDARDS


Standards Australia has recently published four revised

galvanized coating standards that relate to the majority of

galvanized products produced in Australia. These updated

standards replace similar standards that were last revised in

the late 1990s.

The updates cover both continuously galvanized products

(tube, wire and open sections) and batch galvanized

products.

AS/NZS 4680:2006 - Hot dip galvanized (zinc) coatings on

fabricated ferrous articles .

AS/NZS 4680 Is specific to after-fabrication galvanizing and

specifies the heaviest galvanized coatings. In most cases, the

hot dip coating will always exceed the specified minimum

thickness because of the nature of the application process.

Minimum coating thickness is specified on the basis of steel

thickness. The coating is specified in grams/m2 which is

usually converted to average coating thickness in microns so

non-destructive measurement of the coating can be done.

This standard has some minor changes but is very similar

to the 1999 edition. AS/NZS 4680 has been aligned with the

related international standard ISO 4680 as part of Standards

Australias policy of aligning Australian Standards with ISO

(international) Standards.

W h a t s N e w

The coating specifications have been updated to reflect

Australias industry conditions and the latest technology.

They are more user-friendly.

AS/NZS 4534:2006 -Zinc and zinc/aluminium coatings on

steel wire.

AS/NZS 4534 - Is specific to continuously galvanized wire.

The coating is applied in a continuous process. A number of

coating classes are available that vary with wire diameter.

A WXX identification system is used, with W10 being the

standard class against which the other classes are rated. e.g.

W20 is double the coating mass of W10 and W05 is half the

coating mass of W10 for the same wire diameter.

AS/NZS 4791:2006 - ot dip galvanized (zinc) coatings

n ferrous open sections applied by a continuous or

specialised process.

AS/NZS 4792:2006 - ot dip galvanized (zinc) coatings

n ferrous hollow sections applied by a continuous or

specialised process.

AS/NZS 4791 - Open sections

AS/NZS 4792 - Hollow sections

These two standards were developed specifically forOneSteels Duragal continuously galvanized hollow

and open sections and Palmer Tubes and Orrcons hollow

sections manufactured from continuously galvanized (CG)

strip. Some sections may be hot dip galvanized using a

semi-continuous galvanizing process.

Where the hot dip galvanized coating is used, the coating

class is designated by the classification HDGXXX, where the

XX numerals are the coating mass per square metre on

each surface. e.g. HDG200 is 200 g/m2

average.

Where CG strip is used, the coating class is designated byhe classification ZBXXX/XXX. The ZB indicates `zinc both

sides and the XXX is the coating mass per side in g/m2. e.g.

B100/100 represents 100 g/m2

coating mass average on

both sides.

Where the coating is applied by an in-line process

(Duragal ), the coating class is designated by the

classification ILGXXX, where ILG indicates in-line galvanized

and the XXX is the single-side coating mass in g/m2. e.g.

ILG100 represents 100 g/m2

on the outside of hollow

sections and all surfaces of open sections.

W h a t s N e w

Changes to the coating provisions - operating in the

building, construction and engineering industry, you need

o be aware of coatings that are readily available from

manufacturers and coating specifications - outlines an

easy-to-use guide of coatings.


27/322 5

Costs for the revised standards in hard copy from SAI Global

are:

Member Retail

S/NZS 4680:2006 $51.14 $69.52

S/NZS 4792:2006 $51.14 $69.52

S/NZS 4791:2006 $51.14 $69.52

S/NZS 4534:2006 $62.04 $82.72S 1397-2001 $45.87 $61.16

Delivery and handling: $15.95

For printed copies of these publications, order from:

Reply Paid 5420

SAI Global, Customer Service Centre

Sydney NSW 2001

Internet ordering and online catalogue

ww.saiglobal.com/shop

Customer Service Centre

GPO Box 5420 Sydney

NSW 2001

Ph: 131 242

Fax: 1300 65 49 49



28/32 N O V E M B E R 2 0 0 62 6

industrynews

MOLDED FIBERGLASS

COMPANIES FRP PILE REPAIR

SLEEVES EXTEND TIMBER PILE

Editors Note: While this is a US project, the circumstances of

aging harbour infrastructure is a common one that also affects

Australias maritime installations. This New York project offers a

solution to preserving existing timber piling in critical operating

harbor facilities.

P R O J E C T P R O F I L E /C H A L L E N G E

A cleaner Hudson River is in everyones best interest; just

not the piles supporting the New York City Passenger Ship

Terminal (PST) at the Port of New York. In recent years thepollution-laden waters of the Hudson have become cleaner

which has invited the return of wood-boring marine worms

that have infiltrated and eroded the timber piles of the PSTs

three, approximately 1,000 feet long and 125 feet wide,

finger piers.

As part of the New York City Economic Development

Corporations $50 million PST improvement plan, stabilizing

he facilities infrastructure and restoring its structural

integrity were essential to the world-class terminals trade

and transport capabilities.

s severe structural infrastructure deterioration caused by

corrosion exists in concrete, steel and wood all over the

orld, finding restoration vs. replacement solutions is vital

o economic growth and stability. Each year nearly 1 million

passengers pass through the PST, therefore finding the best

pile restoration solution vs. replacing the PSTs deteriorating

piles (which would mean an extremely costly, extended

shutdown) was the projects goal.

New York Citys Passenger Ship Terminal was the recipient of one of the first major pier encapsulation projects to extend the life of the timber

and concrete piles.


29/32


30/32 N O V E M B E R 2 0 0 62 8

industrynews

Munters is world leader in humidity control with

services for dehumidification, humidification and

temperature control.

Project Report:The Ravensthorpe Nickel Mine in Western

Australia - owned by BHP Billiton - is currently under

construction and Munters have been called to assist. Our

brief was to prevent weather related delays and avoid

conditions suitable to coating failures in lining/coating

applications of the internal of nickel refining process tanks.

Munters supplied temporary desiccant dehumidification

an eating systems w ic were size to ac ieve t e

climatic specifications for application and curing.

The use of Munters dehumidification and heating

equipment has ensured specified conditions are being

maintained, preventing the flash rust blooms that reduce

he adhesion of coatings while also eliminating the risk of

inter-coat de-lamination. The dry conditioned air has also

decreased weather related delays to the project, helping to

maintain the completion schedule of the overall tank lining.

MUNTERS PREVENTING

COATING FAILURES

Outside Back Cover [ ] Ingal EPS

Inside Back Cover [ ] Zinifex Limited

Inside Front Cover [ ] Industrial Galvanizers

P l e a s e F a x 0 2 4 9 2 9 7 8 2 7

PLEASE Yes, I would like to know more about the products offered by the following companies appearing inCorrosion Management (Please Tick) FAX 02 4929 7827

EmailPhone ( ) Fax ( )

Name

Type of Business

Position

Company

Page 25 [ ] Australian Taxation Office

Page 28 [ ] Munters

A D V E R T I S E R R E S P O N S EC O R R O S I O N M A N A G E M E N T


31/32

AUSTRALIAS WORLD CLASS

ZINC MANUFACTURER & SUPPLIER

Headquartered in Australia, Zinifex is one of the worlds largest zinc

manufacturers and suppliers, with production facilities spanning three

continents - Australia, Europe and North America.

Wor wi e our zinc n s extensive use or corrosion protection o a

multitude of steel products - steel fabrications, sheet, tubular and wire

products, and fasteners. Each year, over 7 million tonnes of steel are

protected with Zinifex zinc globally.

Our zinc is use or:

ot dip galvanising of steel fabrications

In-line & continuous galvanising of sheet steel, tubulars & wire

roducts

E ectrop ating o stee

anufacture of zinc dust for zinc-rich paints

anufacture of zinc anodes for cathodic protection of steel structures

Zinifex is committed to providing quality zinc products and to supporting

its customers wit expert tec nica service.

Insist on zinc for superior corrosion protection.

Rely on zinifex for quality products and service.

Zinifex Metals Ltd.

evel 29, Freshwater Place

Sout an Bou evar

Sout an VIC 3006

: +61 3 9288 0333

: +61 3 9288 0208

www.zini ex.com

Steve Dunlop

Sa es Manager - Meta s

: +61 3 9288 0281

: +61 3 9288 0208

: steve. un op@zini ex.com

For Sa es Enquiries:

Zinc products:

SHG (99.995%)

Zinc Ingot & Blocks

Continuous

Galvanising Grade

Zinc Alloys

Galvanising Zinc

Toning Alloy

EZDA Zinc Die

Casting Alloy


32/32

Have a burning desire to use timber poles?

By investing in treated timber poles, your wallet might not be the only thing that gets burnt. As concern over the ongoing fire safety of

timber poles mounts, INGAL EPS is pleased to offer a superior alternative. The high strength to weight ratio of steel, combined with

the increased durability and sheer toughness of the hot dip galvanized coating ensure that the steel pole is highly resistant to bushfire

damage. Steel poles are an extremely light weight product delivered in sectional supply making it ideal for installation in remote or

difficult terrain and the modular design system allows easy upgrades throughout the life of the pole. Poles can be either in-ground or

base plate mounted and are designed in accordance with AS 1170.2, AS 4100 and AS/NZS 4600. Being highly resistant to insects, rot

and fire, maintenance costs are substantially reduced and steel poles are also environmentally friendly, being a fully recyclable product.

axiom/

EPS-C

M04

Documents

White Rust Coating