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Training Course Handouts Course held by Jotun Marine Coatings Sandefjord 10 -11 January 2001 Paint School

Paint School

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Page 1: Paint School

Training CourseHandouts

Course held byJotun Marine Coatings

Sandefjord10 -11 January 2001

PaintSchool

Page 2: Paint School

Jotun Paint School Course Handouts Page 1

Jotun Paint School

Course Handouts

Contents

Chapter Title Page

1 Introduction 2

2 What is Paint? 3

3 Generic Paint Types 8

4 Steelwork 15

5 Pre-treatment 19

6 Paint Application 26

7 Inspection and Control 33

8 Paint Failures 41

9 Antifouling 47

10 Safety, Health and Environment (SHE) 53

11 Corrosion 59

12 Cathodic Protection 65

Page 3: Paint School

Jotun Paint School Course Handouts Page 2

1. Introduction

Why paint?There are two main reasons for painting. For many people, the most important reason is thatwe want pleasant surroundings (decorative painting). In other contexts, paints are appliedbecause it is financially very important to protect structures against corrosion. For thesepurposes, corrosion-protective paints are used. A good paint system will be a cost-effectivemethod of protecting the structure: The life of the structure is extended, maintenance costs arereduced and the risk of accidents which affect people and the environment is reduced.

Painting and cathodic protectionFor most applications, painting has been found to be the simplest and most economical way ofprotecting structures, regardless of the exposure environment and your location in the world.

When a structure requires protection, it is important to select a paint system suitable for thepurpose. Paint is a semi-finished product and the protection will be no better than the qualityof the finished coating. The human factor applies during both pre-treatment and application. Apaint system is also often exposed to mechanical wear, which can cause weakness/damage tothe paint film. Where damage occurs, the substrate (normally steel) begins to rust. Jotun hastherefore developed a concept called the "Single Source Solution". This concept enables us toprovide cathodic protection as a back up for corrosion-protective paints. The aim is to ensureoptimum cost solutions for protecting structures exposed to water. Cathodic protectionprotects damaged areas in the paint film.

JotunJotun is one of the world's leading suppliers of corrosion-protective paints for industry,shipping and oil-related sectors. We also supply paints for decorative purposes and powderproducts, based on a worldwide network of factories and companies. To support customers,we have established a wide range of services. This ensures that the customer receives the rightpaint products from our corrosion-inhibiting systems at optimum cost.

Jotun Paint SchoolAs part of our service, Jotun arranges paint courses. These can be courses of more generalcharacter or specific customer-related courses. They focus on the practical use of paint. Tofind out more about these courses, contact your local Jotun office for more information.

Course HandoutsThe course handouts contain a brief introduction to the main topics of paint technology. Eachsection consists of an introductory section and a copy of selected overhead slides. Not alltopics in the handout will necessarily be discussed on the course you follow.

Welcome to the Jotun Paint School !

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Jotun Paint School Course Handouts Page 3

2. What is Paint ?

Definition of paint and varnish

Paint is a product in liquid or powder form which contains pigments and which is applied to asubstrate to form an opaque film. The film has protective and/or decorative properties and canalso be given special functions as required. Paint is described as opaque if it hides thesubstrate completely.

Varnish is a product which, when applied to a substrate, gives a solid transparent film andhas protective, decorative or special properties. Varnish does not contain covering pigmentsand is therefore regarded as "clear paint".

What is paint made of?

The main constituents of paint are binder, pigment, extender (filler), solvent and additives(auxiliary substances).

The binder is the most important component of paint. The binder gives the paint most of itsproperties such as adhesion to the substrate, resistance to weathering, water, chemicals,temperature etc. Binders can be divided into groups (generic types) depending on the dryingor curing process which takes place after the paint has been applied to the substrate. The firstgroup are known as oxidatively drying, as the paint absorbs oxygen from the air and dries.Example: alkyd paints. The next group are called physically drying. When the paint is appliedto the substrate, the solvent simply evaporates. Examples: chlorinated rubber and acrylic. Thethird and final group contains chemically curing paints. These paints are usually two-component, e.g. epoxy.

Pigments in a paint can be colour pigments which give the paint opaqueness, the desiredshade etc. Colour pigments, both organic and inorganic, are available in many shades.Titanium dioxide is a strong colouring, white pigment with good opaqueness and is used inwhite and pale colours. Rust-inhibiting pigments include zinc (cathodic protection) and zincphosphate (inhibiting protection). Such pigments are used only in primers (first coat).

Extenders or fillers such as dolomite, talcum etc. have little or no opaqueness and aretransparent in the binder. They have different forms e.g. balls, needles, fibres etc. and are usedto give a sealed film, the right gloss etc. In antifouling paints, for example, copper oxide isused as a pigment to prevent fouling of ships’ hulls.

Solvents are added to the paint to adjust the viscosity so the paint can be applied by brush,roller or spray gun. Different binders require special solvents or solvent mixtures to be able todry or cure in such a way that the paint properties are not damaged.

Additives are a small, but important, part of the paint. Such substances include antisettlingagents (to prevent fouling), thickeners (to prevent sagging / running), antifoaming agents (toprevent air entrapment), etc.

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Jotun Paint School Course Handouts Page 4

How does paint protect the substrate ?

Paint protects the substrate in three main ways: barrier effect, inhibitor effect and galvaniceffect. Paints which have a barrier effect only form a barrier between the substrate and theenvironment and no rust-inhibiting pigments are added. Most paints come under this group:many primers, all intermediate coats and top coats. Aluminium and glass flakes are often usedin primers to increase the barrier effect.

Paints which use the inhibitor effect contain inhibiting pigments e.g. zinc phosphate. Suchpigments are only used in primers. Paints in this group are not suitable for use under water.

Paints with a galvanic effect contain pure zinc pigments and are used only as primers. Thebasic principle is that the zinc makes metallic contact with the steel so that the zinc can act asan anode. If the paint system is damaged, the zinc pigments will protect the exposed steelcathodically (see section on Cathodic Protection).

What does a paint system consist of?

In most cases, a paint system consists of 2 to 4 coats and is built up from a primer coat, one ortwo intermediate coats and a top coat. The three main constituents in the paint system can bethree different paints, but it is not unusual to use a particular paint as both primer andintermediate coat. Each part of the system has a specific function and it is therefore importantto follow the instructions of the paint manufacturer and the recommended system structure toachieve the best possible result. The main purpose of primers is to ensure good adhesion ofthe system to the substrate. Intermediate coats usually ensure that the system is sufficientlythick to create a good barrier from the surrounding environment. The top coat gives thesurface the right colour, a good durable gloss and protection against the external environment.

A paint system can include more coats than stated above. In brief:

• Shop primer, primarily for the temporary protection of steel from production through tothe construction stage.

• Tie coat, which is applied to porous surfaces to prevent pinholes or to ensure goodadhesion between coats (tie coat).

• Mid coat. More than two are used for paints which cannot be applied in thick coats.

Personal notes

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Chapter: What is Paint ?

Jotun Paint school Handouts Page 5

Paint School1

Paint consist of:Paint consist of:

•Binder•Colour pigments•Extenders•Solvents•Additives

Paint School2

The properties of a paint will beThe properties of a paint will bedecided by the binderdecided by the binder

• Describes the type ofpaint/coating

• Bind pigments andextenders to a solid film

• Provides the adhesion tothe substrate

• Provides the water, chemical,solvent and UV resistance

Paint School3

Oxidising• Alkyd

Physically drying• Chlorinated rubber• Vinyl• Acrylic• Asphalt• Tar

Chemically curing• Epoxy• Polyurethane• Polyester• Silicate

Curing mechanism of bindersCuring mechanism of binders

Paint School4

Oxygen enter.Reaction starts:

Polymer molecules linked together through chemical bonds

Curing (drying) through oxidationCuring (drying) through oxidation

Solvents evaporating

Paint School5

Solvents evaporating

Polymer molecules stick together (no chemical bonds):

Physical drying.Physical drying.Solvent borne paintsSolvent borne paints

Polymer molecules are packing:

Paint School6

Physical dryingPhysical dryingWaterborne paintsWaterborne paints

= Dispersed droplets

Water evaporating

Droplets are packing

Droplets melt together, co-solvents evaporate

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Chapter: What is Paint ?

Jotun Paint school Handouts Page 6

Paint School7

= Polymer = Curing agent (hardener)

Solvents evaporating

Curing mechanism of Curing mechanism of two -pack paintstwo -pack paints

Polymer & hardener molecules reacted to form a new chemical substance:

Paint School8

VinylChlorinated rubberEpoxyPolyurethane

Urethane alkydAlkydBoiled linseed oilRaw linseed oil

The surface tolerance depends on the The surface tolerance depends on the penetrating properties of the binderpenetrating properties of the binder

Surface tolerant paint:Epoxy Mastic

Paint School9

Rust preventing pigments:• Red Lead• Zinc• Zinc Chromate• Zinc phosphate

Extender pigments (non/limited hiding/opacity properties):• Talcum• Barium sulphate• Microdol (dolomite)

Pigments, examplesPigments, examples

Coloured pigments (hiding power / opacity):• Inorganic; red, yellow, brown, black• Organic, all colours• Titan dioxide (white)

Paint School10

The Gloss of a paint depends on the PVCThe Gloss of a paint depends on the PVC(Pigment - Volume - Concentration)(Pigment - Volume - Concentration)

Colour pigments

Binder

Extenders

SemiglossPVC 30 - 40

FlatPVC 35 - 50

GlossyPVC 15 -25

Paint School11

• Dissolve the binder• Give lower viscosity• Give application properties

for brush, roller, spray

Solvents / Solvents / diluentsdiluents

Paint School12

Solvent or Solvent or diluentdiluent

• Single or blended• Disolves the binder completely

(Forms a solution)

• Single or blended• Does not dissolve the binder (Forms a “mixture”)• Used in conjunction with solvents

DiluentDiluent

SolventSolvent

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Chapter: What is Paint ?

Jotun Paint school Handouts Page 7

Paint School13

Addition of thinnerAddition of thinner

Evaporation rate and solubility of athinner will influence a paint’s:

• Drying time• Film-forming properties• Quality of the film

❶ Most paints are ready to be applied as supplied by the manufacturer.❷ Never add an unspecified thinner to a paint, it may lead to disastrous results

Paint School14

• Wetting agent• Anti-foam• Anti-settling• Anti-skin• Anti sagging• Catalysts• UV-absorbers etc.

AdditivesAdditives

Paint School15

Corrosion protection by paintsCorrosion protection by paints

• Barrier effect• Inhibitor effect• Galvanic effect

For corrosion prevention with paints, three mainprinciples are employed:

Paint School16

PrimerSteel

1st coat2nd coat

Impervious to ions,oxygen, carbon dioxide

Low moisture transmission

Strong adheringcoating thoroughly wets steel surface Physical as well as

chemical adhesion

No voids at interfaceto accumulate water

Clean surface - no saltsto create osmotic blistering

An impervious coating serves as an An impervious coating serves as an inert barrier to protect the surface inert barrier to protect the surface

Paint School17

Moisture may penetrate to reach the inhibitiveprimer where the reactive pigments are activated, which in turn

passivate the metal substrate at the coating/metal interface.

InhibitionInhibition

Inhibitive Primer1st Coat2nd Coat

Steel

Moisture Absorption

Ionisation of InhibitorReaction with Steel Surface

Passive layer forms

Paint School18

Inorganic Zinc Primer

2nd Organic Topcoat

Superior adhesion prevents coating undercut

Moisture allows Zinc toionize, cathodically protecting the steel.

Damage in coating to steel surface

An inorganic Zinc primer reacts to protect thesteel substrate when the topcoat is damaged.

Cathodically protective pigments Cathodically protective pigments

SteelZn2+

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Jotun Paint School Course Handouts Page 8

3. Generic Paint TypesIt is not possible to develop a "universal" paint which fulfils all possible functions. Paints aretherefore developed for different jobs. As a result, each paint has a different set of properties.Paints are often grouped according to the chemical composition of the binder, which we referto as ‘generic paint types’. To ensure that you choose the right paint or paint system with theright properties, it is important to know the strengths and weaknesses of the various generictypes.

Alkyd paints

Alkyd paints are made from alcohol and acid with the addition of fatty acid or oil. Theaddition of fatty acid and/or oil can be varied to give alkyds with different properties.

Alkyd paints can only be used above water (not submerged) as the water resistance is poor.They are not used on zinc primer or galvanised steel as a chemical reaction - saponification -would occur with the binder, with subsequent blistering and flaking. The drying/curingprocess is also temperature-dependent. This is because alkyd paints dry or cure by absorbingoxygen from the air. This is a chemical reaction and such reactions are always influenced bytemperature.

The degree of pre-treatment required for the substrate can vary from St 2 to Sa 2½, dependingon the purpose of the paint and the environment to which the paint is exposed. By modifyingthe alkyds for example with styrene or silicon, other properties can be achieved.

Physically drying paints

The group of physically drying paints contains generic types such as chlorinated rubber (CR),vinyl and acrylic-based paints. These are being withdrawn from the market due to the highcontent of volatile organic compounds (VOC). The chlorinated compounds in CR paints alsogive off chlorine on ageing.

Physically drying paints are single-component, and dry by pure evaporation of the solvents.This means that these paints are not so sensitive to the ambient temperature during applicationand drying (does not apply to waterborne acrylic). They are also resoluble by other paintswhich contain strong solvents or in contact with thinners.

CR paints are used outdoors both above and under water. Vinyl-based paints are used onlyabove water. Acrylic is used as a top coat, as it retains its gloss better than chlorinated rubberor vinyl in such systems. acrylic is also used as primers in waterborne systems.

Chemically curing paints

Chemically curing paints are thermosetting plastics, unlike physically drying paints which arethermoplastics. Thermosetting plastics are more resistant to chemicals than thermoplastics asthey form an insoluble three-dimensional network after curing.

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Jotun Paint School Course Handouts Page 9

These paints are normally two-component. The supplier provides these paints in two separatecontainers, one for the base and the other for the curing agent. We often refer to these ascomponent A and component B. Before painting, the two components must be mixed. It isparticularly important to mix the components in the correct ratio and to ensure good agitation.The curing process is a chemical reaction between the base and curing agent, so applicationand curing are temperature-dependent. It is equally important to apply the paint to thesubstrate before the chemical reaction has proceeded for too long after mixing of thecomponents. We often talk of the usage time (potlife) of paints. When the potlife has elapsed,the paint becomes dry and finally completely hard and cannot be applied.

Some chemically curing paint types

Epoxy paints have excellent chemical resistance, particularly to alkalis. They have goodadhesion both to steel and concrete and good water resistance. Epoxy can be modified usingphenol, coal tar and hydrocarbon resin to give special properties, e.g. better chemicalresistance, better penetration, better water resistance etc. One drawback with many epoxypaints is that they contain large quantities of solvent. However, other types have now beendeveloped with a high solids content (mastic products) with excellent "all round" properties.There are also a solvent-free epoxy paints which are used for drinking water tanks.Waterborne Epoxy paints are increasingly being used today because they give a betterworking environment. Chemical resistance however is slightly reduced.

Zinc epoxy (organic) or zinc ethylsilicate (inorganic) are used as cathodic protective primerson blast-cleaned substrates. Zinc ethylsilicate (solvent-based) and alkali silicate (waterborne)are also often used inside storage tanks for solvents because of the extremely good solventresistance.

Polyurethane paints are also thermosetting plastics. They are used as top coats on epoxy(which chalks in sunlight) as they have excellent weather-resistance and durable gloss.

Polyester paints are thick coat paints used in areas where a high degree of wear resistance isrequired. For example gangways, production decks, dam walls (concrete) for power stationsetc. These paints are applied in thick coats (e.g. 2 x 750 µm) and cure quickly (a few hours).They also have good chemical resistance.

Vinylester is also a thick coat paint (2 x 750µm). It has good chemical resistance and is oftenused inside storage tanks for chemicals. Such paints can be used on both steel and concrete.

Personal notes

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Chapter: Generic types

Jotun Paint school Handouts Page 10

Paint School1

• Good applicationproperties

• 1-component• Good weather durability• Good wetting properties• Good recoatability• Good levelling properties• Good gloss retention• Dry heat resistant up to

120 ºC.

• Poor chemical resistance(especially againstalkaline)

• Limited water resistance(submerged)

• Limited solvent resistance• Limited film thickness per

coat• Poor adhesion to CR• Never to be used on Zinc

Alkyd paintsAlkyd paintsPropertiesProperties

Advantages Limitations

Paint School2

• Ships• Industry

• Newbuildings / Maintenance• All exterior and interior objects• Only above water

• St 2 to Sa 2½ or shop primedsteel

Segments

Objects

Surface preparation

Alkyd paintAlkyd paintWhere to useWhere to use

Paint School3

Advantages• Physically drying• Not temperature

dependent• Easy to recoat• One component• Very good water

resistance• Relatively good chemical

resistance

Limitations• Poor solvent resistance• Low solid content• Relatively poor wetting

properties• Thermoplastic• Dry heat resistant up to

approx. 70 °C

Chlorinated Rubber paintsChlorinated Rubber paintsPropertiesProperties

Paint School4

Chlorinated Rubber paintsChlorinated Rubber paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• Below and above water• All external surfaces

• Blast-cleaned to Sa 2½ or shopprimed steel

Segments

Objects

Surface preparation

Paint School5

Advantages Limitations• Low solid content • Poor resistance against strong solvents• Dry heat resistant up to approximately 80 ºC

Used for:

Vinyl paintsVinyl paintsPropertiesProperties

• Physically drying • Good chemical resistance• Good water resistance• Quick drying• Not temperature dependent• One-component

Exterior objects above water Offshore on top of Zinc-ethylsilicate

Paint School6

Advantages• Higher content of

solids• Higher water

resistance• Better wetting

properties• Cost advantages

Disadvantages• Bleeding• Dark colours• Tar on cancer list

Used for: Under water areas

Vinyl Tar - Modified typeVinyl Tar - Modified typePropertiesProperties

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Chapter: Generic types

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Paint School7

Advantages

• Chemical curing• Very good chemical resistance• High alkali resistance• Moderate resistance to acids• Good adhesion• Very low permeability• High mechanical strength• Dry heat resistant up to 120 °C

Limitations

• Chalking• Temperature dependent• 2 - component• Requires blast cleaning• Overcoating time

Pure Epoxy paintsPure Epoxy paintsPropertiesProperties

Paint School8

Pure Epoxy paintsPure Epoxy paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• Chemical cargo tanks

• Blast-cleaned to Sa 2½ or shop primed steel

Segments

Objects

Surface preparation

Paint School9

Advantages:• Chemically curing • More flexible

• Excellent water resistance

• Better wetting properties

• Dry heat resistant up to 90 °C

Limitations:• Dark colour

• Temp. dependent

• 2-component

• Recoating interval

• Bleeding when overcoated

• Coal Tar is carcinogenic

Epoxy Coal TarEpoxy Coal TarPropertiesProperties

Paint School10

Epoksy - acrylicEpoksy - acrylicPropertiesProperties

• Very good weatherresistance

• Very good gloss retention• Very good chemical

resistance• Very good solvent

resistance• Cures down to 0 °C• Potlife (24 timer)

• 2-pack• Overcoating time

Positive Limitations

Paint School11

Epoksy - acrylic pintsEpoksy - acrylic pintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• Above water• Indoor and outdoor

• Top coat on Epoxy, Epoxy• Mastic, Polyester glass flake

Segments

Objects

Surface preparation

Paint School12

Advantages• Chemically curing • Surface tolerant • Light colours• Very good water resistance • Very good wetting properties • Good chemical resistance• High solid content• High build (Thick coats) • Winter curing agent• Dry heat resistant up to 90 ° C

Limitations

Epoxy Mastic paintsEpoxy Mastic paintsPropertiesProperties

• Chalking• Temperature dependent• Not to be applied on thick coats of physically drying paints• Minimum DFT 150 µm by airless spray

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Chapter: Generic types

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Paint School13

Epoxy Mastic paintsEpoxy Mastic paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• Ballast tanks and Cargo tanks• All exterior and interior surfaces,

above and below water• St 2 to Sa 2½ or Water jetted,

Magnesium descaled or shopprimed steel

Segments

Objects

Surface preparation

Paint School14

• Correct mixing ratio• Good mixing• Potlife• Induction time• Correct pre-treatment• Correct film thickness• Adequate ventilation

• Temperaturedependent curing

• Avoid high humidity• Minimum and

maximum curingtimes

• Time for fully cured• Use epoxy thinner• Health and epoxy

ExperienceExperienceWhen using Epoxy paintsWhen using Epoxy paints

Paint School15

• Very good weatherresistance

• Excellent glossdurability

• Very good chemicalresistance

• Very good solventresistance

• Cures down to 0 °C

• 2-pack• May cause skin

irritation• Overcoating time

Polyurethane paintsPolyurethane paintsPropertiesProperties

Advantages Limitations

Paint School16

Polyurethane paintsPolyurethane paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• All exterior substrates above

water (Also internal at times)• On top of Epoxy, Epoxy Mastic

and Polyester coatings

Segments

Objects

Surface preparation

Paint School17

Zinc EpoxyZinc EpoxyPropertiesProperties

• Chemically curing• Good corrosion protection• Good adhesion• Require min. Sa 2 ½• Good mechanical strength• May be recoated with all

types of paint, except Alkyd• Dry heat resistant up to 120

ºC

• Temperature dependent• 2-component• Film thickness: 25 - 50 µm• Not acid- and alkaline

resistant(Resistant between pH 5-9)

Advantages Limitations

Paint School18

Zinc Epoxy paintsZinc Epoxy paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• All exterior and interior objects

above and below water (as holdingprimer for underwater use 20-30microns).

• Blast-cleaning to minimum Sa 2½

Segments

Objects

Surface preparation

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Chapter: Generic types

Jotun Paint school Handouts Page 13

Paint School19

Zinc Zinc EthylsilicateEthylsilicate paints paintsPropertiesProperties

• Very good solvent resistance• Very high heath resistance

(max 400 oC)• Very high mechanical

strength• Very good adhesion to blast

cleaned steel• Relatively good re-

coatability

• Requires humidity forcuring

• 2-pack• Max. DFT: 100 µm

At higher DFT tendencyof mud-cracking orchecking

Advantages Limitations

Paint School20

Zinc Zinc EthylsilicateEthylsilicate paints paintsWhere to useWhere to use

• Ships• Offshore• Industry

• Newbuildings / Maintenance• All exterior objects above the

waterline.• Tank coating and Water ballast tank

(No paint on top)• Blast-cleaning to minimum Sa 2½

Segments

Objects

Surface preparation

Paint School21

Aluminium Silicone paintsAluminium Silicone paintsPropertiesProperties

• Pure aluminium silicone:Resistant up to approximately 600°C

• Modified aluminium silicone:Resistant up to approximately 400°C

• To be applied in thin coats only (20 µm)Heavier coats may give blistering

Remember:To be applied on Sa 2 ½Overcoating only on fully cured Zinc silicate

Paint School22

Waterborne acrylicsWaterborne acrylicsAdvantages andAdvantages and LimitationsLimitations

• Good corrosion protection• Reduce the emission of

solvents• Low VOC content• Flash point above 100 ºC• Water as thinner / cleaner• Good water resistance• Good UV - resistance• Good adhesion to other

generic type of paints• No risk of saponification

• Due to water-solublegroups, more sensitive toaqueous solutions (moreblistering/earliercorrosion)

• Slower drying comparedto solvent based types athigh relative humidity

• Need good ventilation• Need good pre-treatment• Less chemical resistance

Advantages Limitations

Paint School23

Waterborne epoxyWaterborne epoxyAdvantages and limitationsAdvantages and limitations

• Good corrosion protection• Reduced emission of solvents• Low VOC content• Flash point above 100 ºC• Water as thinner / cleaner• Good water resistance• Cures down to 5 ºC• Good adhesion to steel,

galvanized steel, Aluminiumand concrete

• Good sprayability

• Need good ventilation at highhumidity

• Must be stored above 0 ºC• Shorter potlife compared with

solvent borne• The same health hazards as

solvent borne Epoxies• Due to water-soluble groups,

more sensitive to aqueoussolutions

Advantages Limitations

Paint School24

Recommended conditionsduring application and drying

Application and drying possible

Application not recommended

10 20 30 40 50 60102030405060708090

100

Temperature ( oC)

Relative humidity (%)

Waterborne paintsWaterborne paintsConditions during applicationConditions during application

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Chapter: Generic types

Jotun Paint school Handouts Page 14

Paint School25

GlassflakeGlassflake Reinforced Polyester Reinforced Polyester

• For protection of steel and, in certain cases,Aluminium and concrete.

• The glass-flakes are 3-5 microns thick and400 microns across.

• Potlife : Approximately 45 minutes.• Curing time: Approximately 3 hours.• Thickness 600 - 1500 microns per coat.

Paint School26

GlassflakeGlassflake Reinforced Polyester Reinforced PolyesterPropertiesProperties

Advantages• Quick curing• Variable curing time• Application with airless• Excellent mechanical strength

• Glass-flakes reduce shrinkage,increases mechanical strengthand water resistance.

• Very good chemicalresistance

Limitations• Temperature dependent• Short potlife• Recoating interval

2 - 12 hours

• Bad curing may beexperienced on Zinc primersand galvanised surfaces.

Paint School27

GlassflakeGlassflake Reinforced Polyester (Styrene free) Reinforced Polyester (Styrene free)PropertiesProperties

Advantages• Styrene free• Dry to handle in 2 hours• Cures down to 5 ºC (2-component pump)• Excellent mechanical

strength

• Very good adhesion

• Very good water resistance.

• Very good chemicalresistance

Limitations• Cures down to 10 ºC

(normal airless spray)• Short potlife• Recoating interval

1 hour to 2 weeks (23 ºC )• Require Sa 2 ½ and a roughness

of 50-100 microns

• Bad curing may be experiencedon Zinc primers and galvanisedsurfaces.

Paint School28

Vinyl ester coatingsVinyl ester coatings

Glass-flake reinforced Vinylester coatingfor protection of steel and concrete

in aggressive environments.

Paint School29

Vinyl ester coatingsVinyl ester coatingsAdvantages and limitationsAdvantages and limitations

• Very fast curing• Very good adhesion• Very good abrasion

resistance• Very good chemical

resistance• Very good solvent resistance• Can be applied by normal

airless spray• Glassflakes improve abrasion

resistance

• Very fast curing• Very good adhesion• Very good abrasion

resistance• Very good chemical

resistance• Very good solvent resistance• Can be applied by normal

airless spray

Advantages Limitations

Paint School30

Application ofApplication ofPolyester and Vinyl ester coatingsPolyester and Vinyl ester coatings

• Capacity of pump, min.12 l/min (airless)

• Material hose: 3/8”• Use teflon gaskets• Nozzle: 0,035-0,053

Angle 40 - 80 o

• Remove filters• Check the W.F.T.

• Check ventilation, light etc.• Thinner No. 17 or 15,

Acetone for flushing orcleaning

• Only on blast-cleaned steel• Proper mixing• Short potlife

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Jotun Paint School Course Handouts Page 15

4. SteelworkBefore a structure is painted, a number of operations must be performed on the substrate. Theinitial work required is generally known as "steelwork". Steelwork is a very important part ofthe surface treatment and must be carried out before cleaning and priming of the steel. Goodsteelwork will ensure that the life time of the paint system meets expectations. In practice, it isimpossible to achieve a long life time for a paint system if the steelwork is omitted or poorlyperformed. The requirements for preparation will always be part of the paint specification.

A steel structure should be designed so that all parts of the structure are accessible forcleaning, pre-treatment and painting. It is particularly important to ensure that theserequirements are taken into account at the newbuilding / construction stage. Designers oftenforget that structures require maintenance.

Steelwork involves the following stages before cleaning and priming:

1. All sharp edges are rounded to a radius of at least 2 mm by grinding.2. All welding beads and slag are grinded off.3. Surface defects such as lamination etc. are removed by grinding.4. Undercutting in the weld is repaired before priming.5. Rough manual welds to be grinded.6. Gas-cut edges are to be grinded before priming.

To avoid contamination and damage to the coating, steelwork should be performed in thewelding shop and not in the paintshop. Production times will also be reduced if sharp edges innotches, manholes etc. are rounded before welding work is performed. All welds should beinspected and if necessary repaired before cleaning is carried out. The welds must be freefrom weaknesses such as undercut, hole, craters and welding splashes.

Notched, drainage holes etc. should have a radius of at least 50 mm to ensure good primingand correct paint application.

Personal notes

Page 17: Paint School

Chapter: Steel work

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Paint School1

Rounding or smoothing of:Sharp edgesCornersWelds

Grinding of:LaminationsFlame cut edgesWeld spatter

Pre-blasting preparation Pre-blasting preparation involves the following activitiesinvolves the following activities

Notches minimum diameter: 30 mmInspected and approved before cleaning

See ISO 8501 “Visual assessment of surface cleanliness”

Paint School2

A

B

Gas cut edgeA. Remove by grinder or disc sander.

B. Rolled steel sections normally have round edges. Therefore can be left untreated.

A. Remove visible spatter before grit- blasting with grinder or chipping hammer.

B. For spatter not readily removed, remove using grinder/disc.

Sharpedge

Weldspatter

A

B

Steel preparationSteel preparationEdges and weld spatters Edges and weld spatters

Paint School3

Coating applied to a square-cut section

Pre-blasting preparationPre-blasting preparationRounding sharp edgesRounding sharp edges

Reduced coating thickness at sharp edges due to tension created during drying / curing

CoatingSharp edge

Rounded edgeEven coating thickness

Steel

Paint School4

Grinding of sharp edges, welds etc.Grinding of sharp edges, welds etc.Disc sander and disc grinderDisc sander and disc grinder

Sander for removing millscale, paint and rust

Grinder for heavy grinding,such as edges and weld beads

Paint School5

Steel support afterSteel support afterblast-cleaning to Sa 2 ½blast-cleaning to Sa 2 ½

The sharp edges should have been roundedprior to blast-cleaning

Paint School6

Steel support afterSteel support afterblast-cleaning to Sa 2 ½blast-cleaning to Sa 2 ½

The sharp edges have been rounded prior to blast-cleaning:Good !

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Chapter: Steel work

Jotun Paint school Handouts Page 17

Paint School7

Manholes in a tankManholes in a tank

• Section manholes• Well grinded edges

Paint School8

Severe corrosion due to aSevere corrosion due to acombination of several effectscombination of several effects

• Sharp edges• Rough welds (not grinded)• Missing stripe coating

Paint School9

Grinding of notch with rotating fileGrinding of notch with rotating file

Easy access with a rotating file

Paint School10

Steel preparationSteel preparationWeld spatter, welding smokeWeld spatter, welding smoke

WeldWeldspatter Areas at risk

Paint School11

Disc grinding of weld beads, sharpDisc grinding of weld beads, sharpedges etc. by means of a disc grinder.edges etc. by means of a disc grinder.

Other types of discs are available.Some of them will reduce the amount of sparks.

Paint School12

Steel substrate after disc grindingSteel substrate after disc grinding

Weld beads etc. has been removedto form an acceptable substrate for the paint system

Page 19: Paint School

Chapter: Steel work

Jotun Paint school Handouts Page 18

Paint School13

Remove using grinder

Undercuts exceeding classification rulingshould be repaired by welding and grinding.

Sharp profile peaks to be smoothed usinggrinder

Lamination

Undercut

Manual weld bead

Pre-blasting preparationPre-blasting preparationLaminations, undercuts, welding seamsLaminations, undercuts, welding seams

Paint School14

Unacceptable weld.Unacceptable weld.Too rough and full of pinholes / poresToo rough and full of pinholes / pores

• Weld spatters close to weld• Rewelding and grinding must be carried out

prior to reblasting and painting

Paint School15

Paint on a very poor weld. Pinholes andPaint on a very poor weld. Pinholes andholidays visible after second stripe coatingholidays visible after second stripe coating

• Neither rewelding nor grinding have beencarried out prior to application

• Remedial Actions: Reblasting, rewelding,grinding and blast -cleaning: COSTLY

Paint School16

Early corrosion of welds in aEarly corrosion of welds in awater ballast tankwater ballast tank

• Rough weld seams.Should have beengrinded

• Probably incombination withpoor stripe coating

• Mud can be seen,particularly on thebottom

Paint School17

Not recommended solution for exposure to severe /aggressive environments

Spot welding leads to crevicesSpot welding leads to creviceswhich are susceptible to corrosionwhich are susceptible to corrosion

Paint School18

Sharp edge an spot welds.Sharp edge an spot welds.Early corrosion attackEarly corrosion attack

• Construction newlypainted

• Exposed to humidatmosphere

• Corrosion initiatesafter a short period oftime on weak areas:Sharp edges, crevicesand spot welds

Page 20: Paint School

Jotun Paint School Course Handouts Page 19

5. Pre-treatmentAfter the steelwork on the steel structure has been completed, inspected and approved, pre-treatment can begin. The purpose of preparation is to ensure that the substrate is suitable forapplication of the paint, i.e. the steel is sufficiently clean and rough. Contaminants such as oil,grease and salts for example cannot be removed by blast-cleaning. Before preparation begins,the steel must be properly cleaned. Cleaning removes contamination and impurities such asoil, grease, salt, dust and dirt.

Salts from a marine atmosphere which are deposited on the structure, and welding fumes frommanual welding are examples of salts which should be washed off before preparation. Saltscan cause osmotic blistering and oil will reduce the adhesion of the paint. Salts must beremoved with plenty of fresh water. Oil and grease cannot be removed with water alone;strong alkali washing agents and solvents must be used.

Once the substrate is clean, pre-treatment can begin. There are countless methods which canbe used, all of which have advantages and disadvantages. Here is a brief list of some methods:

Blast-cleaning. To ensure maximum paint adhesion, a rough surface is required. In view ofthis, blast-cleaning is the best preparation method. Blast-cleaning removes old paint, rust andscales and gives a clean rough surface. Possible blast-cleaning methods are dry blast-cleaning,slurry blast-cleaning (addition of water) and wet blast-cleaning (water with addition ofabrasives). Dry blast-cleaning gives a clean dry surface and the required roughness but causesconsiderable dust which contaminates the immediate environment. Slurry and wet blast-cleaning give a rough, clean surface without dust, but create flash rust. It has been found thatmuch of the abrasives remain on the substrate after blast-cleaning. Such contaminants may onsome alloys cause a risk of corrosion at these points. For preparation of stainless steel,aluminium and galvanised steel, it is important to use non-metallic abrasives.

Ultra high-pressure water cleaning. This preparation method is becoming increasinglycommon. The method consists of removing contamination, corrosion products and old paintby applying water to the substrate under extremely high water pressure (up to 2500 bar). Themethod has two essential advantages: no cloud of blasting dust is created to contaminate theimmediate environment as in traditional blast-cleaning, and water-soluble salts are removedfrom the substrate. It is important to use clean water so that the substrate is not contaminatedby the water used. The method gives a clean surface but will not give any extra roughness tosteel. The original roughness of the steel is retained where intact paint is removed, but thecorrosion pattern on corroded areas will be considered as roughness where corrosion hasoccurred. One disadvantage with water cleaning is that the tendency to form flash rust on thesteel will increase as moisture is added to the substrate. The degree of flash rust depends onthe relative humidity, the temperature of the steel and atmosphere, and the cleanliness of thesurface.

Mechanical cleaning. Use of mechanical cleaning tools such as steel brushes, grindingequipment or machining, does not achieve the same degree of cleanliness and roughness asblast-cleaning and the adhesion between the substrate and the paint system will therefore bereduced. Needle guns for example often cause excessive roughness or break-up of thesubstrate.

Page 21: Paint School

Jotun Paint School Course Handouts Page 20

Electrolytical descaling. There is a special preparation method where magnesium strips areused to remove rust. This has proved particularly useful in severely corroded ballast tanks onsailing ships where thick rust layers can be removed at sea. However, the procedure requires aknowledge of how to calculate the number of anodes needed, installation of the anodes,treatment periods and cleaning after the procedure. Such treatment should therefore be carriedout in collaboration with Jotun.

The method to be used will be described in the paint specification and is primarily selectedon the basis of:

� Purpose of the structure� Exposure conditions� Required life time� Restrictions related to environmental requirements and safety.

One essential element of the entire pre-treatment process is care when performing the work.Today, the inspection is performed with reference to various standards. The most commonstandards are ISO 8501 which gives a visual description of the appearance of a steel surfaceboth before and after blast-cleaning and wire brushing. For water-blasting/water-jetting,separate standards have been prepared by ISO and SSPC/NACE.

Personal notes

Page 22: Paint School

Chapter: Pretreatment

Jotun Paint School Handouts Page 21

Paint School1

• Steel work (Pre-blasting preparation)• Removal of:

– Rust and mill scale– Salt– Grease, oil, dirt– Old / unwanted paint

• Flattening of glossy paint• Special pre-treatment of new aluminium

and galvanised surfaces

Surface treatment may include Surface treatment may include the following operationsthe following operations

Paint School2

• Salt and soil: Clean water

• Oil - grease: Solvent with emulsifying agent or alkaline cleaner

Work to be carried out Work to be carried out in the cleaning shopin the cleaning shop

Remove prior to pre-treatment:

Paint School3

Degreasing side bottom with emulsifyingDegreasing side bottom with emulsifyingdetergent to remove oil, grease etc.detergent to remove oil, grease etc.

• Should always be carried out before blast-cleaning• The detergents must be removed by ”Low pressure

water cleaning, LPWC” (Around 250 - 300 bar)

Paint School4

Equipment contaminating the surfaceEquipment contaminating the surfaceOil contamination from grinderOil contamination from grinder

Reasons may be:• Oil leaking out of

equipment• Equipment has been

stored with oil• Lack of oil trap.

(Air from compressorcontains oil)

Must be removed prior to surface preparation

Paint School5

Welding smoke is water solubleWelding smoke is water solubleand can only be removed by waterand can only be removed by water

• Solvents will notremove the weldingsmoke completely

• If not removed,osmotic blisteringmay occur.

Welding smokeArea washedwith water

Paint School6

Blisters close to weld, probably due toBlisters close to weld, probably due towelding smoke remaining on the the steelwelding smoke remaining on the the steel

• Welding smoke is resoluble in water and willcreate osmotic blistering

• Galvanic difference between steel plate and weldmay aggravate the attack

Page 23: Paint School

Chapter: Pretreatment

Jotun Paint School Handouts Page 22

Paint School7

Pre-treatmentPre-treatmentEvaluation of methodsEvaluation of methods

Blast cleaningPower grinding

Power wire-brushingManual wire- brushing.Needle hammer

Power chiseling

Manual scraping

IdealNot as good as blast cleaning, but

best alternative.Great risk of unwanted polishing.Not recommended. Very poor.Usable, but risk of unwanted rough

surface,Good in combination with other

methodsUsable in combination with other

methods.

Paint School8

Rotary impact or scarifying toolsRotary impact or scarifying tools

• Peening flaps (Roto-Peen) - Creates a surface profile, 25 to 75 microns• Rotary hammers - cutters• Nylon non-woven abrasive wheels

Rotary impact tools is the best choice for removing coatings

Equipment with rotating abrasive head

Paint School9

Grinders and sandersGrinders and sanders

• Coated abrasive discs- To remove paint, mill scale and rust

• Non-woven abrasive discs- To remove paint and rust and for feathering of paint

• Wire brushes- To remove loose rust (tends to polish surface)

Paint School10

Steel substrate treated by hand andSteel substrate treated by hand andmechanical power tool cleaning equipmentmechanical power tool cleaning equipment

Hand wire brush, approximately St 2

Mechanical wire brush approximately St 3

Paint School11

Pre-treatmentPre-treatmentIllustration of various blasting methodsIllustration of various blasting methods

Paint School12

Dry blastingDry blastingBenefits and limitationsBenefits and limitations

Advantages

• Surface remains dry• Good anchor pattern

for paint• No pre-rusting profile

Disadvantages

• Does not remove salt• Does not remove oil• Creates dust

Page 24: Paint School

Chapter: Pretreatment

Jotun Paint School Handouts Page 23

Paint School13

• Productivity is directly proportional to: Pressure at Nozzle Capacity of the air compressor

• Pressure at Nozzle 7 kg/cm² = 100% productivity

• Pressure at Nozzle 5,6 kg/cm² = 66% productivity

• Pressure at Nozzle 4,2 kg/cm² = 50% productivity

Blast cleaningBlast cleaningFactors influencing the production rateFactors influencing the production rate

Paint School14

Nozzle Nozzleholder

Air

Blast - cleaningBlast - cleaningMeasure the air pressure at the nozzleMeasure the air pressure at the nozzle

Rubber hose

Pressure gauge

Paint School15

Blast cleaning: Effect of nozzleBlast cleaning: Effect of nozzlepressure on cleaning rate.pressure on cleaning rate.

Nozzle pressures, Kg / cm²

Cleaning time: 2 minutesSource: Clemtex Ltd.

Remaining Removed

Paint School16

The blast hose shall have an opening which is 3-4 times

bigger than the orifice of the nozzle.

Blast Cleaning Blast Cleaning Rule of thumb: To avoid loss of pressureRule of thumb: To avoid loss of pressure

Hose opening Nozzle opening

3 - 4 times

Paint School17

Corroded area. Subsequent spot blasting

Solid coating

Feathered requiredImpact by abrasives

(SOURCE: Munger, C.G. Practical aspects of Coating Repair.

Materials Performance, Vol. 19, No 2 p. 46 (1980)

Blast cleaningBlast cleaningImpact damages may destroy overlapping zoneImpact damages may destroy overlapping zone

Originally corroded area

Paint School18

Blast cleaningBlast cleaningAbrasives will damage the coatingAbrasives will damage the coating

Cracks due to direct impact by abrasives 3-Coat paint

Corroded and blast cleaned

Area withreduced adhesion

Steel

Area require feathering

Page 25: Paint School

Chapter: Pretreatment

Jotun Paint School Handouts Page 24

Paint School19

Blast cleaningBlast cleaningAbrasives will damage the coatingAbrasives will damage the coating

Steel

Areas with reduced adhesion

3-coat paint systemStar crack areasImpact of abrasive

May be caused by direct impact or rebounding abrasives (ricochet)

Paint School20

Blast cleaningBlast cleaningCorrect and incorrect sweep blastingCorrect and incorrect sweep blasting

Star cracks

Abrasives approx. 0.5 mmPressure approx 2-3 kg / sqcm

Often abrasives of 0.2 - 1.4 mm and too high pressure is used

Paint School21

Corrosion has taken placeCorrosion has taken placeAlmost the total area has been spot blastedAlmost the total area has been spot blasted

• Spot blasting in this way result in many looseedges that needs to be feathered

• Recommendation: Blast - clean larger areas

Bare steel

Top coat

Antifouling

Paint School22

Loose edges resulting from spot-Loose edges resulting from spot-blasting carried out some time agoblasting carried out some time ago

• Edges has not been feathered prior to application of the paint• The edges are weak points in the paint film• Corrosion attack initiates on such areas

Paint School23

Surface has not been well cleanedSurface has not been well cleanedOver painting grit or foreign mattersOver painting grit or foreign matters

• Weak point in paint film• Entrapped air• Less adhesion• Corrosion will develop rapidly

Paint School24

Poor cleaning of ballast tanksPoor cleaning of ballast tanks

• Abrasives remaining from blast cleaning• 300 µm Coal Tar Epoxy• Blistering and rust penetration after 10 months of exposure

Page 26: Paint School

Chapter: Pretreatment

Jotun Paint School Handouts Page 253

Paint School25

Slurry and wet blastingSlurry and wet blastingBenefits and limitationsBenefits and limitations

Advantages

• Surface profile isachieved

• Removes salt• Creates no dust.

Disadvantages

• Flash rust maydevelop on surface

Paint School26

• Salt level on steel surface drastically reduced.• No dust produced.• No grit cost (water is usually cheaper).

Grit blasting uses 55 kg/m², costing £ 63,-/ton = 3,46/m².Ultra High Pressure Water Jetting, UHPWJ needs 130 l/m²,costing £ 0,80/ton = £ 0,10/m²).

• Close working of other trades possible.• Abrasives can be introduced if improved surface profile is

required.• Lower noise level than with grit blasting.

Water-jettingWater-jettingAdvantagesAdvantages

Paint School27

• Degreasing and washing• Sweep blasting with non-metallic abrasive• Abrading through other means, e.g.

mechanical tools, emery paper etc

Pre-treatment ofPre-treatment of Stainless steelStainless steel

Paint School28

• Degreasing and washing• Sweep blasting with non-metallic abrasiveor• Abrading through other means, e.g.

mechanical tools, emery paper etcor• Washing with a strong alkaline cleaner

followed by washing with clean wateror• Wash primer (Not in combination with

Epoxy paint)

Pre-treatment ofPre-treatment of AluminiumAluminium

Paint School29

Pre-treatment of hot-dipPre-treatment of hot-dipgalvanised steel.galvanised steel.

• T-wash• Sweep blasting• Etch primer, single or two - pack• Natural weathering for at least

twelve months

Paint School30

Electrolytic de-scaling.Electrolytic de-scaling.Working processWorking process

• Empty the ballast tank• Mount the Magnesium strips• Fill the tank with seawater• Ballasting period of 1-2 weeks• Empty the tank• Remove calcareous deposit immediately

(Water pressure: 250 to 300 bar)• Remove loose rust and scale• Remove iron cores• Dry the tank• Start application of paint

Page 27: Paint School

Jotun Paint School Course Handouts Page 26

6. Paint ApplicationIt is important to understand that paint is a semi-finished product. Only once the paint hasbeen applied to a structure will the real properties of the paint system become apparent. Howwell a system works largely depends on the skill of the painter. The protective properties of apaint can be significantly reduced if the paint is applied incorrectly.

Application technique

To apply the paint to achieve the optimum properties, it is important to select the rightapplication tool and method. Generally application tools are selected according to the size ofthe object, complexity, accessibility, type of paint and environmental aspects.

Painting always begins with "stripe coating". Stripe coating means applying an extra coat ofpaint on areas where experience has shown that it is difficult to achieve the specified filmthickness by spray. Typical areas which should be stripe coated are sharp edges, notches,welds (particularly manual welds) and areas which are difficult to reach with a spray gun.This is a very important job but it is often skipped or done badly as it is a time-consumingprocess. Stripe coating on bare steel should always be carried out with a round or oval brushand not a roller. The aim is to ensure good wetting of the substrate. Stripe coating should alsobe used between each coat. A stripe coat can be applied with a roller on the previous coatwhere suitable. The film thickness achieved using brushes or rollers is normally in the rangeof 35 - 40 µm.

Airless spraying is the most effective and cost-saving application method. It is possible topaint large areas in the minimum of time and paint can be applied in greater and more evenfilm thicknesses per coat than with a brush and roller. The application technique andexperience of the painter are very important for achieving a good result. This includes factorssuch as the right distance between the gun and object (normally 30 to 60 cm), the right angleto the object (normally 90 degrees), good overlapping (approx. 50% overlap) and sensitivityin use of the trigger. When spraying, the paint is applied at as low a pressure as possible toachieve an even spread. Too high a pressure leads to dry spraying and a lot of dust.

Checks to be carried out during application

The painter only has one instrument available for checking the film thickness duringapplication: wet film gauge (comb or wheel). It is important to use the cam regularly. Thisensures good checking during the entire application process so that the correct film thicknessis achieved over the entire structure. The atmospheric conditions should always be checkedduring application of paint, and the correct ventilation ensured, especially in tanks. Theseconditions must be monitored throughout the application process and whilst the paint isdrying / curing.

Mixing and thinning

Do not add unnecessary quantities of thinner to the paint as this causes slower drying and youwill have to apply the paint in greater wet-film thicknesses to achieve the same dry film. Use

Page 28: Paint School

Jotun Paint School Course Handouts Page 27

of the correct (specified) thinners is important as adding the wrong thinner can cause poorresults in terms of corrosion protection.

When applying two-component paints, the mixing process itself is also important. Usemechanical agitators and not stirrers. Good agitation or mixing of the two components and thecorrect mixing ratio are important. Follow the instructions on the technical data sheet for theproduct. Plural component spray (two-component spray) are also available for applyingspecial two-component paints, where the components are mixed in the correct ratio in the unititself.

Health

The painter is exposed to solvents and various other components in the paint. Make sure thatapproved protective equipment is used and that ventilation is adequate.

Personal notes

Page 29: Paint School

Chapter: Paint Application

Jotun Paint School Handouts Page 28

aint School1

ApplicationApplication

Cleanliness and good housekeeping before,during and after application are one of the most

important factors to have a good result

Paint School2

Tools for mixing of paintsTools for mixing of paints

• Always use mechanicalagitator to ensure propermixing.

• Proper mixing will not beachieved by a stirrer

• A stirrer may also containdirt and loose parts thatmay contaminate the paintand clog the sprayequipment

Paint School3

Consequence of inferior mixing:Consequence of inferior mixing:Poor coating performancePoor coating performance• To the right: Correct mixing and mixing ratio.• To the left: Insufficient mixing and / or incorrect

mixing ratio.

Paint School4

Airless spray:Good

Paint brush:Good

Roller:Poor, particularly for the first coat

Methods for paint applicationMethods for paint application

Paint School5

Application by paint brushApplication by paint brush

Benefits• Good wetting of the substrate• Forces the paint into the surface• Better than roller on the first coat• Good on areas with poor accessibility

Limitations• Gives low film thickness, many coats required• Creates an uneven film• Application speed is slow

Paint School6

Benefits• Application speed is faster than with paint brush• Good on areas with poor accessibility

Limitations• Poor wetting of the substrate• Never use for the first coat• May incorporate air and pinholes in the paint film• Gives low film thickness, many coats required

Application by rollerApplication by roller

Page 30: Paint School

Chapter: Paint Application

Jotun Paint School Handouts Page 29

Paint School7

ApplicationApplicationStripe coating prior to each full coatStripe coating prior to each full coat

• Where difficult access with spray• Profiles • Inside edges• Holes, notches• Corners, angles• Sharp edges • Manual welding seams

Stripe coat with paint brush:

Paint School8

Stripe coating of superstructureStripe coating of superstructurebetween first and second full coatbetween first and second full coat

• Pipes• Supports• Windows• Reeling

Note the contrasting colours.Excellent work

Paint School9

Poor workmanship:Poor workmanship:Stripe coated welding seamStripe coated welding seam

• Many holidays• The paint must be worked properly into the rough

substrate using several strokes with the paint brush.

Paint School10

• Correct distance between spray gunand substrate: (30-60 cm)

• Correct angel (90°)

• Overlapping (50% or cross application)

Paint application.Paint application.Rules when sprayingRules when spraying

Paint School11

Seek to keep the gun at aSeek to keep the gun at aright angle to the substrateright angle to the substrate

The distance should be between 30 and 60 cm. The optimaldistance will vary, among other things with wind,

temperature, pressure at the nozzle and viscosity of the paint .

Paint School12

50 %

OverlapOverlapping ensures an even film thickness

Paint application. Paint application. Airless spraying with overlapAirless spraying with overlap

Page 31: Paint School

Chapter: Paint Application

Jotun Paint School Handouts Page 30

Paint School13

Application with a spray gun.Application with a spray gun.Stroke and triggeringStroke and triggering

Start stroke →→→→ Pull trigger →→→→ Release trigger →→→→ End stroke

Structure

Paint School14

• As the coating droplets hit the substrate they will become flat. • Then, they will overlap and form a continuous paint film

Formation of a paint filmFormation of a paint film

Paint School15

Area of effective spraying

Outside area of effective spraying:• Low impact• Poor flow of paint• Result: Dry-spray

Overspray or dry-sprayOverspray or dry-spray

Dry-spray will develop at the edges of a wide spray fan.This may give a rough film and pinholes

Paint School16

Incorrect application technique.Incorrect application technique.Waving with the gunWaving with the gun

Result:• Uneven paint film• Dry-spraying will occur• The loss factor will be high• The roughness will increase

Paint School17

• A rough surface• Too much paint dust• Pinholes in the paint film• Entrapped air• Entrapped solvents• Too high paint consumption

Incorrect use of airless spray Incorrect use of airless spray equipment will result in:equipment will result in:

Paint School18

Spraying of a ship’s bottom.Spraying of a ship’s bottom.Very poor application techniqueVery poor application technique

• Too long distance• Dry spraying• Uneven film thickness

Running wateralong side the shipwhile painting.(Scupper plug missing)

Page 32: Paint School

Chapter: Paint Application

Jotun Paint School Handouts Page 31

Paint School19

Poor application techniquePoor application techniqueserves nobodyserves nobody

• Contamination ofthe environment

• High loss factor• Poor corrosion

protection• Waste of money

Paint School20

Spot-blasting andSpot-blasting andpoor application technique.poor application technique.

• Loose paint edges• Application has been

done in only onedirection

• Corrosion hasdeveloped on shadowsides shortly afterapplication

Direction of application

Paint School21

Application TechniqueApplication TechniqueWith Spray GunWith Spray Gun

Positioning of the spray gunCorrect Wrong

Parallel Perpendicular Arcing Tilting

Over spray Heavy Light

Light

Paint School22

Source: Corr. Control Principles and Metodes, Sect. 7, Ameron Inc., Monterey Park, Ca.)

Spray application technique.Spray application technique.Apply one extra coat to cornersApply one extra coat to corners

Wrong Correct

Paint School23

Application directly into the corner gives an uneven film thickness,but may still be satisfactory for many types of service

(Source: Industrial Maintenance Painting, National Association of Corrosion Engineers; Houston TX, p. 88, 1973.)

Area with thick paint film

Area with thin layer of paint

Application of inside cornersApplication of inside corners

Air cushion is formed

Paint School24

(Source: Industrial Maintenance Painting, National Association of Corrosion Engineers; Houston TX, p 88, 1973)

1

23

54

Application of inside cornersApplication of inside corners

• Spray each side of the corner separately• Use a vertical spray pattern• This will give an even film thickness

Page 33: Paint School

Chapter: Paint Application

Jotun Paint School Handouts Page 32

Paint School25

Air will be compressed in pits and push the paint back.This makes use of airless spray on such areas almost impossible

Application technique:Application technique:

Surfaces with deep pitsSurfaces with deep pits

Paint School26

Inside a tankInside a tankRuns leading to cracking of paintRuns leading to cracking of paint

• Paint has collectedin the corner

• Several mm thickpaint

• The paint cracked,corrosion willdevelop

Paint School27

Paint not applied according to thePaint not applied according to thespecification. Close up of paint filmspecification. Close up of paint film (2 of 2)(2 of 2)

• Specification : 50 µm• Thickness of topcoat:

100 - 150 µmResult:• Entrapped air• Entrapped solvents• Porous film• Blisters and

delamination willoccur in future

Paint School28

• Relative humidity, %• Ventilation• Temperature• Film thickness• Number of coats• Evaporation speed of solvents

What factors influenceWhat factors influencethe drying / curing process ?the drying / curing process ?

Paint School29

Temperature of substrate should be ata temperature of

min. 3oC

above dew point of the air in thevicinity

Main rule for pre-treatment Main rule for pre-treatment and paint application:and paint application:

Paint School30

Temperature and humidityTemperature and humidityof air used for drying.of air used for drying.

• Supply of heated air immediately after application maylead to skin drying and entrapped solvents

• Cold air will keep the film open longer and ensure properevaporation

• Avoid high air temperature (especially epoxy)• High humidity will slow down the drying time• Exhaust from heating equipment using propane or paraffin

oil contain water and Carbon dioxide and may createAmine sweating

Page 34: Paint School

Jotun Paint School Course Handouts Page 33

7. Inspection and ControlThe human factor is an important element in the process to ensure the specified quality of thepaint system. It is therefore very important to inspect and control all work performed inconnection with surface treatment. During the manufacture of a structure, inspections andcontrol should be performed at the following critical phases:

• Steelwork• Pre-treatment• Before, during and after application.

For all activities, the inspector should verify and document that the work complies with thespecification and has been performed professionally, and that the paint supplier's instructionsfor use of the product have been followed.

Steelwork

Activities which are normally included in the preparation are described in chapter 4. Theinspector should verify that the steelwork has been performed according to specification orISO 12944-3. In particular, this includes the rounding of edges, grinding of welds, removal ofweld spatters and grinding of laminations.

Pre-treatment

The inspector must check and ensure that the structure is free from oil, grease and salt andthat the washing procedure has been followed. Visual assessments shall be made of the degreeof rust on the steel before preparation and the condition of the structure after preparation.Standards ISO 8501-1 or ISO 8501-2 (for repair work) apply. Before and during pre-treatment, the atmospheric conditions are checked according to ISO 8502-4. Other checks tobe performed usually include inspection for invisible contamination on the surface such assalts (ISO 9502-6 and 9), dust (ISO 8502-3) and specified roughness (ISO 8503). All data andrecords shall be entered in a daily log.

Application of paint

The inspector's task during application of the paint is to ensure that all work proceeds in thespecified manner. This includes all work operations from opening of the paint tin to theapplication of the final coat. It is important to have a good overview of all technicaldocumentation. Check technical data sheets and check for use of the right thinners, the rightcuring agent for the base, mechanical agitators and a good mix when using two-componentpaints. Check the specified pre-reaction time if given in the technical data sheet. Check thatstripe coating has been performed properly before application of the full coat by spraying.Ensure that the painter carries out careful checks with using wet film gauge so that thespecified wet film thickness is applied. The atmospheric conditions should be monitoredduring the painting work. Ensure adequate ventilation to remove solvents. All data andrecords must be entered in a daily log.

Page 35: Paint School

Jotun Paint School Course Handouts Page 34

Drying / curing

After drying / curing, the dry film thickness is checked (ISO 2808). Pay particular attention toareas where access with an airless spray gun is difficult, and ensure that the dry film thicknesslies within the specified limits. Check that the overpainting intervals are observed for thepaints, and that the surface is clean before overpainting. After a structure is painted, the totalfilm thickness should be checked. Individual specifications also require adhesion testing forexample to ISO 4624, or holiday detection to ASTM G62-85. It is very important to havegood test routines and enter all data and records in a daily log.

Personal notes

Page 36: Paint School

Chapter: Inspection and Control

Jotun Paint school Handouts Page 35

Paint School1

What is QA - QC ?What is QA - QC ?

QA = Quality Assurance (A documented management system)

QC = Quality Control (Inspection and testing routines)

Paint School2

An inspector’s work includes:An inspector’s work includes:

• Be capable of interpreting the specifications• Understand the objective of the inspection• Inspect all structures to be painted• Ensure that all specified requirements are met• Document the results from the inspections• In case of non-conformance: Issue written reports

Paint School3

Daily logsDaily logs

• Steel temperature• Air temperature• % Relative Humidity• Dew point• Object no. and name• Exact specification• Pre-treatment, specified and

actually conducted.

• Film thickness (to bemeasured also at spot repair)

• Area, m²• Product name, place of

production and batch no.• Name of relevant persons• What was discussed• Non conformance report

(remember signatures)• Other comments

Paint School4

• All paints that will be used• All relevant inspection methods and inspection tools• Relevant standards• Relevant TDS and MSDS• Methods involved in cleaning, pre-treatment

and paint application• The equipment used for pre-treatment and

application: Benefits and limitations

An inspector needs to knowAn inspector needs to know

Paint School5

What needs to be inspected ?What needs to be inspected ?

• Shop-priming of the steel• The steel work (Pre-blasting preparation)• Cleaning and surface preparation

prior to paint application• Application of paint• The applied paint film and its

curing/drying conditions.

If relevant, the following stages of the production need to be inspected

Paint School6

Inspection of steel workInspection of steel work(Pre-blasting preparation)(Pre-blasting preparation)

• Rounding of sharp edges.• Smoothing of rough welding seams.• Removal / grinding of weld spatter and beads.• Cracks and pittings.• Surface faults like laminates etc.• ISO 12944 - 3 , or ISO 8501 - 3

The following items need to be inspected during construction

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Paint School7

Inspection of cleaning and surfaceInspection of cleaning and surfacepreparation prior to applicationpreparation prior to application

• Cleanliness (salt, oil, grease and dust/dirt)• Evaluation of present condition (rust grade)• Surface preparation (e.g. blast cleaning)• Cleanliness of prepared surface

(salts, oil, grease, dust and dirt)• Climatic conditions

(temperature, relative humidity etc.)

If relevant, the following conditionsmust be inspected / verified

Paint School8

ISO 8501 - 1ISO 8501 - 1Surface preparationSurface preparation

• Visual assessment of surface cleanliness after blast cleaning, hand or power tool cleaning or flame cleaning

• Rust grades and preparation grades of uncoated steel

• Photographic examples of steel when blast cleaned with different abrasives

Paint School9

ISO 8501 - 2ISO 8501 - 2Surface preparationSurface preparation

As for ISO 8501-1, but: For steel where previous coating has been removed

locally, not completely.

Paint School10

PSa : Localised blast cleaning (grades 2, 2 ½ and 3)

PSt : Localised hand and power tool cleaning (grades 2 and 3)

PMa : Localised machine abrading (one grade)

ISO 8501 - 2ISO 8501 - 2Standard for deciding preparation gradesStandard for deciding preparation grades

Paint School11

ISO 8502ISO 8502Assessment of surface cleanlinessAssessment of surface cleanliness (1 of 2)(1 of 2)

Part 1 Field test for soluble iron corrosion products

Part 2 Laboratory determination of chloride on cleaned surfaces.

Part 3 Assessment of dust on steel surfaces prepared for painting (pressure- sensitive tape method)

Part 4 Guidance on the estimation of the probability of condensation prior to paint application.

Part 5 Measurement of chloride on steel surfaces prepared for painting. Ion detector tube method.

Paint School12

ISO 8502ISO 8502Assessment of surface cleanlinessAssessment of surface cleanliness (2 of 2)(2 of 2)

Part 6 Extraction of soluble contaminants for analysis. The Bresle method.

*Part 9 Conductometric measurements of soluble salts

.

* Part 7, 8 and 10 are not prepared

*

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Paint School13

Surface temperature of the

structure must be minimum

3 °C above the dew point

of the surrounding atmosphere

Atmospheric conditions.Atmospheric conditions.Requirement during blasting and paintingRequirement during blasting and painting

Paint School14

• Ambient temperature will influence:– shelf life– pot life– viscosity/sprayability– steel temperature

• Steel temperature will affect:– speed of cure– degree of cure– recoating interval– service life of the coating

Ambient temperature andAmbient temperature andsteel temperaturesteel temperature

Is the temperatures important ? YES !

Paint School15

ISO 8502 - 6ISO 8502 - 6The Bresle method.The Bresle method.

A method for extraction ofsoluble contaminants on

steel substrates for analysis:

The Bresle method

This is a quantitative test

Paint School16

ISO 8502 - 9ISO 8502 - 9ConductometricConductometric measurement of soluble salts. measurement of soluble salts.

Field method for measuring soluble saltsby conductivity (µ S) of solutions

containing water soluble salts

Paint School17

Calculation of salt levelCalculation of salt levelon the substrateon the substrate

(L(L22 - L - L11) x 6 = mg salt per m) x 6 = mg salt per m22

L2 = µS after cleaning

L1 = µS before cleaning

Water sample, ml.: 10 15 20 50Constant in formula: 4 6 8 20

Formula:

Paint School18

Instruments for measuringInstruments for measuringsurface roughnesssurface roughness

• Stylus instruments• Elcometer Mod. 123• Testex Press-O-film• Microscope• Comparator

–Rugotest No. 3–ISO 8503 etc.

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Chapter: Inspection and Control

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Paint School19

ISO 8503ISO 8503Surface roughnessSurface roughness

• Example of a referencecomparator

• Surface profile comparatorcomprising four segments.

• Grit (G)• Shot (S)• Check if the profile is

according to specificationand the paintmanufacturer’srecommendation

Paint School20

Inspection during applicationInspection during application

• Record name of coating and batch no.• Ensure proper mixing of 2-pack paints• Ensure use of the correct thinner• Measuring the wet film thickness (WFT)• Number of coats as given in the specification• Cleanliness between coats (salts, dust, oil etc.)• Drying time / recoating intervals• Control of equipment: Pressure, nozzle etc.• Climatic conditions (Ventilation, Air and steel temperature and the relative humidity)

The following must be verified, inspected or tested:

Paint School21

Information to be found from theInformation to be found from thetechnical data sheet, TDStechnical data sheet, TDS

• Product description– Generic type etc.

• Recommended use– Where to use the product

• Technical information– Solids by volume, WFT,

DFT• Application data

– Methods, mixing, potlife• Surface preparation

– Different methods given

• Conditions duringapplication

• Drying and overcoating timeat different temperatures

• Typical recommendedsystem

• Storage• Handling• Packing control• Health and safety

– Details in MSDS

Paint School22

Method 1:

Method 2:

Method 3:

Method 4:

Method 5:

Determination of wet film thickness.

Determination of dry-film thickness bycalculation from mass

Measurement of dry-film thickness bymechanically contacting method

Measurement of dry-film thickness by theprofilometer method

Measurement of dry-film thickness usingmicroscope method

ISO 2808 - 97ISO 2808 - 97Determination of film thickness Determination of film thickness (1 of 2)(1 of 2)

Paint School23

Method 6:

Method 7:

Method 8:

Method 9:

Method 10:

Magnetic method

Eddy current method

Non-contact methods

Gravimetric method (dissolving methods)

Determination of dry-film thickness onblast-cleaned steel substrates

ISO 2808 - 97ISO 2808 - 97Determination of film thickness: Determination of film thickness: (2 of 2)(2 of 2)

Paint School24

Calculations : PaintCalculations : PaintAbbreviationsAbbreviations

WFT = Wet Film ThicknessDFT = Dry Film Thickness% VS = Percent Volume SolidsLF = Loss FactorDV = Dead Volume

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Paint School25

Example:

WFT = 250 µm

% VS = 50 %

DFT = = 125 µm

WFT x % VS100

250 x 50100

Formula for determining the DFTFormula for determining the DFT

Formula: DFT =

Paint School26

Consumption of Paint with lossConsumption of Paint with loss

Epoxy mastic = 196 litre

Polyurethane topcoat = 83 litre

500 x 200 10 x 85 x 0,6

500 x 50 10 x 50 x 0,6

To be painted: Tank, area of 500 m2 , 40 % loss

40 % loss implies that only 60 % will remain on the surface. The correction factor, Loss factor, will be 0.6

Formula: Area, m2 x DFT 10 x % VS x loss factor

Paint School27

Dead volumeDead volume increases theincreases thevolume of paint requiredvolume of paint required

Steel

Smooth (polished) steel surfaceEven film thickness

Steel

Uneven steel surfacePaint will fill the valleys

Specified thickness

Dead volume

Paint School28

How much paint should we order ?How much paint should we order ?calculation of paint consumption with losscalculation of paint consumption with loss

Example: 100 litre is needed, loss is 40 %We have to order

= = 167 litre

Not 100 litre + 40 % extra = 140 litre

100 x 100 60

100 0,6 (loss factor)

A loss of 40 % means that only 60 % will be applied on the surface

Paint School29

Inspection after applicationInspection after application

• Climatic conditions (Ventilation, Temperature and humidity)• Curing / drying of the film• Dry film thickness (DFT)• Adhesion• Holiday detection (if required)

After application the following must be checked

Paint School30

• Electromagnetic instruments• Calibration on a smooth steel surface min. 1,2 mm thick• For DFT measurement, not less than 25 and preferably

above 50 microns• Number of readings, as a guide:

– 1 reference area: At least 3 readings evenly– 2 reference areas for every square meter for flat plates– 4 reference areas for every length for a web– 2 reference areas every metre length for a flange– 2 reference areas every metre length for a pipe

ISO 2808 - 97ISO 2808 - 97Determination of film thicknessDetermination of film thickness

Method No. 10 - On blast cleaned steel substrates

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Paint School31

ASTM D 3359-87ASTM D 3359-87Adhesion testing by knife and adhesive tapeAdhesion testing by knife and adhesive tape

• There are two test methods• The method to select depends on the DFT

Method A: DFT above 125 micronsMethod B: DFT below 125 microns

(Above 125 if wider cuts are used)

Method A: X - cut. Tape testMethod B: Cross - cut. Tape test

Paint School32

ISO 2409ISO 2409Cross-cut testCross-cut test

Cutting toolSingle bladed knife

orMulti-blade cutting tool with 6 cuttingedges spaced 1 mm or 2 mm apart

Spacing of cuts 0 - 60 microns: 1 mm spacing, hard substrates 0 - 60 microns: 2 mm spacing, soft substrates60 - 120 microns: 3 mm spacing, hard/soft substrates121 - 250 microns: 3 mm spacing, hard/soft substrates

Paint School33

ISO 4624ISO 4624Pull-off test for adhesionPull-off test for adhesion

Procedure:• Test dollies glued onto the coating• Adhesive: Cyano-acrylate or solvent free epoxy• Remove adhesive and coating around the dollies• Pull off test-dollies vertical to the surface• Read adhesion value and report the type of fracture

Fractures:• Adhesion failure - fracture between coats or substrate and 1. coat• Cohesion failure - fracture within a coat

Paint School34

ASTM G 62 - 85 Method AASTM G 62 - 85 Method APinhole detection. Pinhole detection. LowLow voltage.voltage.

• Low voltage: < 75 V DC• To detect pinholes, voids or metal particles to be

in the range of 25-250 microns.• Effective for paint films up to a DFT of 500

microns if a wetting agent is used in the water.• This is a non-destructive test.

Paint School35

ASTM G 62 Method BASTM G 62 Method BHoliday detection. Holiday detection. High High voltage.voltage.

High voltage: 900 - 20.000 V

Used to detect pinholes, voids andareas with thin paint films

This is a destructive test.

Paint School36

ISO 12944ISO 12944General standard for corrosion protection:General standard for corrosion protection:

Part 1 General introduction.Part 2 Classification of environments.Part 3 Design considerations.Part 4 Types of surface and surface preparation.Part 5 Protective paint systems.Part 6 Laboratory performance test methods.Part 7 Execution and supervision of paint work.Part 8 Development of specifications for new work

and maintenance.

Paints and varnishes - Corrosion protection of steel structures by protective paints systems.

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8. Paint FailuresAs we have already said, paint supplied in containers is a semi-finished product. The finishedproduct only exists once the paint has been applied to the structure in a complete paint system.This is where we see how good the protection is. The most important and most common paintfailures occur as a result of poor or insufficient steelwork, preparation or application. Some ofthese faults are revealed during or shortly after application but some only appear after acertain period in service. The most common failures during and just after application are:

• Insufficient film thickness• Sags / runs• Dry spraying• Pinholes• Amine sweating

Insufficient film thickness is often the result of non-systematic application and inadequatechecks with a wet film gauge.

Sags / runs occur when the paint is applied too thickly or too much thinner has been added tothe paint. This is probably because the specification has not been followed. Occasionally,faults are also found in the paint. The inspector must note the production number in the dailylog. Sags / runs should be repaired immediately with a brush.

Dry spraying is normally a result of poor application or difficult weather conditions. Themost common application fault is too great a distance between the spray gun and the structure.High temperature combined with low relative humidity will also contribute to dry spraying asthe solvents evaporate en route from the gun to the object. Strong wind or strong ventilationalso contributes to an increased risk of dry spraying.

Pinholes often occur on porous substrates, for example zinc silicate. On these substrates, it isimportant to apply a thin layer of paint, normally called a tie coat or by using the mist coat -full coat technique. Pinholes are also found if there is too strong ventilation duringapplication.

Amine sweating can occur on epoxy paints during curing in particularly humid environments.The phenomenon results in a sticky surface, occasionally visible as white stains. These mustbe removed before overpainting using rags and tepid water (thinners for some paints). Therisk of amine sweating is reduced by observing the specified induction time after mixing thetwo-component paint and ensuring good atmospheric conditions during application andcuring.

The most common paint faults after exposure are:

• Blistering• Rust penetration• Cracking• Flaking• Chalking

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Such faults can be assessed using standard ISO 4628.

Blistering is normally an adhesion-related problem and is due to poor cleaning beforeapplication of the paint. The most common cause of blistering is the application of the paint toa substrate contaminated with salt (osmotic blistering). After blisters have formed, they burstand the underlying unprotected material begins to rust if rust formation has not alreadystarted. Osmotic blistering occurs on exposure under water or in areas with heavycondensation. In particular, the salts sodium chloride and ferric chloride, and welding smoke,cause blistering. Other causes of blistering can be dust or grit on the surface (reducesadhesion), voids between the steel and the paint or trapped air in the paint film. Blistering isevaluated according to ISO 4628-2.

Rusting occurs after a blister in the paint film bursts. The failure will occur most quicklywhere the paint film is too thin. Particularly susceptible areas are sharp edges, rough weldsand places which are difficult to access for application. If rusting occurs after a very shorttime without prior blistering, there will be an opening through to bare steel, i.e. a pinhole.Rust penetrationevaluated according to ISO 4628-3.

Cracking occurs after a certain ageing of the coating. The causes can be:

• The top coat is harder than the coats underneath• Excessively thick system combined with temperature variations• Excessively fast curing of two-component systems• Excessively thick zinc silicate gives "mud cracking".

There are various degrees of cracking. Cracks can either form in the top coat only orthroughout. The time before the fault occurs can vary. Mud cracking occurs immediately afterapplication but cracking occurs only after a certain time. Cracking is evaluated according toISO 4628-4.

Flaking is normally the result of a poorly cleaned substrate (oil, grease) or the paint beingapplied onto condensation or surfaces with amine sweating. Paint will frequently flake offfrom areas with blistering or cracking and occurs where adhesion is poorest. Flaking isevaluated according to ISO 4628-5.

Chalking is an ageing problem. The binder is degraded by UV radiation from the sun and thepigments appear as dust on the surface. The paint's ability to resist chalking will varyaccording to the binder used. Epoxy will chalk in sunlight after just a few months whereaspolyurethane will retain its gloss for many years. Chalking is evaluated according to ISO4628-6.

Personal notes

Page 44: Paint School

Chapter: Paint Failures

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Paint School1

Most common paint failuresMost common paint failures

• Holidays, too low DFT• Sags and runs• Orange peel• Dry spraying• Overspray• Pinholes, popping• Fish-eyes• Wrinkling / lifting

• Sweating (Amine)• Blushing• Poor drying / curing• Blisters• Rust penetration• Cracking• Flaking• Chalking• Discolouration/bleeding

Paint School2

Sags and runsSags and runs

Appearance• Paint running or hanging like curtains on vertical surfacesCaused by• Too high Wet film thickness• Too much thinner added to the paint• Airless spray gun too close to surfaceRepair• Avoid above• Use paint brush to smoothen or remove excessive paint

Paint School3

Orange peelOrange peel

• Paint surface is rough, like an orange peel

• Poor flow / levelling properties of the paint(Paint too thick or too low temperature)

• Poor atomisation of the paint• Too fast evaporation of the thinner• Airless spray gun too close to surface

• Improve application technique• Use correct thinner• Grind surface and apply new paint

Appearance

Caused by

Repair

Paint School4

Dry sprayDry spray

• Porous, sandpaper like surface of the paint• Poor atomisation of the paint• Spray gun too far away from the object• High air temperature and low relative humidity: Too fast

evaporation of the solvents• Strong wind during application• Inorganic Zinc: Re-blast and apply new paint• Physically drying paints: Apply thinner on the painted

surface and apply a new coat• Oxidativly drying paints: Remove loose dust and apply

topcoat• Two-pack paints: Remove loose dust, sandpaper to

smooth surface, apply topcoat

AppearanceCaused by

Repair

Paint School5

PinholesPinholes

Appearance• Tiny holes through one or more coats, or even down to the

substrate, as if perforated by a needleCaused by• Dry spraying• Entrapped solvents or air• Porosity of previous coat• Incorrect application technique or viscosity of the paintRepair• Grind top layer of the paint• Recoat

Paint School6

Pinholes / poppingPinholes / popping

Solvents or air try to evaporate through the upper partof the film, which has already nearly dried, leavingsmall bubbles /craters on the surface

• Very porous substrate (e.g. Zinc silicate primer)• Entrapped solvents or air in the paint film• Usually in connection with too high film thickness,

too long application distance or too strong ventilation.

• Reduce film thickness or ventilation and adjustapplication technique (Tie coat / mist coat technique.

• Remove paint on painted surfaces and repaint

Appearance

Caused by

Repair

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Paint School7

FisheyesFisheyes

Appearance• Spots of paint on the surface with no wetting of the

surface around the spots. Appearance of a fisheye.Caused by• Paint applied on oil, silicone or other contaminants• Painted on incompatible paint (Glossy paint giving

poor wetting)Repair• Grind top layer of the paint• Recoat

Paint School8

WrinklingWrinkling

Appearance• Small wrinkles through or partly through the paint filmCaused by• Skin drying of the paint film, which is usually applied

too thickRepair• Grind top layer of the paint• Recoat

Paint School9

LiftingLifting

Appearance• Small wrinkles through the paint filmCaused by• Softening and raising or swelling of a previous

coat by the application of an additional coat• Normally when overcoating Alkyd• Lifting often caused because the solvents in the

new coat is too strong for the previous coatRepair• Remove the paint• Recoat

Paint School10

Sweating and carbonisationSweating and carbonisation(Amine blooming)(Amine blooming)

Appearance• Tacky and sweating film, often with white stainsCaused by• High humidity, particularly on Epoxies during curing• Poor ventilation• The Amines react with CO2 and humidity and form

Amine carbamate.• Too low temperatureRepair• Wash with warm water or thinner, using ragsPreventive measure: Induction time before application start

Paint School11

Bloom and blushBloom and blush(Blushing)(Blushing)

Appearance• Surface looks milkyCaused by• Condensation on cold steel surfaces at high humidity• Air pollution, sulphur dioxide (SO2) and ammonia

forming ammonium sulphate on the paint film.• “Fast “ thinnersRepair• Grind top layer of the paint• Recoat

Paint School12

ISO 4628ISO 4628Content of the StandardContent of the Standard

Part 1 General principles and rating schemesPart 2 Designation of degree of blisteringPart 3 Designation of degree of rustingPart 4 Designation of degree of cracking

Part 5 Designation of degree of flakingPart 6 Designation of degree of chalking

The standard consists of six parts

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Paint School13

ISO 4628 - 2ISO 4628 - 2Degree of blisteringDegree of blistering

Density 2 Density 3

Density 4 Density 5

Blisters of size 5

Paint School14

ISO 4628 / 3ISO 4628 / 3Designation of degree of rustingDesignation of degree of rusting

RatingDesignate the degree of rust formation byreference to the pictorial standards

Degree Area rusted %Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

0

0,05

0,5

1

8

40/50

Paint School15

ISO 4628 / 3ISO 4628 / 3Designation of degree of rustingDesignation of degree of rusting

Test report:The test report shall contain at least the following information:a) the type and identification of the product testedb) a reference to this International Standard (ISO 4628/3)c) the numerical rating of the rusted aread) the numerical rating of the size of the rust spots, if desired, for example: Rust: Ri 3 (S4) = rusted area, as a percentage of rust, approximates standard 3,

the sizes of the individual rust spots of the order of a fewmillimetres.

e) the date of the examination

Paint School16

Pinpoint rustingPinpoint rusting

Appearance• Points of rustCaused by• Small pores (pinholes), openings or defects in

the paint film down to bare steel• Holidays due to overspray, dry spraying etc.• Too high substrate roughnessRepair• Grind down to bare steel• Recoat

Paint School17

ISO 4628 / 4ISO 4628 / 4Designation of degree of crackingDesignation of degree of cracking

Test report:a) the type and identification of the product testedb) a reference to this International Standard (ISO 4628/4)c) the numerical rating of the quantity of crackingd) the numerical rating of the size of crackinge) the depth of cracking (a. b. or c), where possible, for example: cracking 2 (S3) b

If necessary, the standard assessment may be amplified inwords, for example “linear cracking”. The use of suchcomments shall, however, be avoided wherever possible

e) the date of the examination

Paint School18

ISO 4628 - 4ISO 4628 - 4Evaluation of crackingEvaluation of cracking

Quantity

1 2 3 4 5

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Paint School19

ISO 4628 / 5ISO 4628 / 5Designation of degree of flakingDesignation of degree of flaking

Test reportThe test report shall contain at least the following information:

a) the type and identification of the product testedb) a reference to this International Standard (ISO 4628/5)c) the numerical rating of the quantity of flakingd) the numerical rating of the size of flakinge) the depth of flaking (a or b),

for example: flaking 3 (S2) a

Paint School20

ISO 4628 - 5ISO 4628 - 5Evaluation of flaking.Evaluation of flaking.

Quantity

1 2 3 4 5

Paint School21

ChalkingChalking

• Almost like dust on top of the coat• The gloss will be reduced

Pigments and extenders exposed onthe paint surface, due to

• Exposure to sun / UV light• Degradation of the binder• Weathering of the paint• Insufficient mixing of the paint

• Grind and/or wash top layer of the paint• Recoat

Appearance

Caused by

Repair

Paint School22

BleedingBleeding

• Discolouration of a paint, particularly intopcoats

• Coloured ingredients in a previous coat or onthe substrate is dissolved by solvents in thesubsequent coat, e.g.

• Soluble pigments (Poor solvent resistance)• Tar, Bitumen, etc.• Surface contaminants (coloured)• Re-blasting and re-application

Appearance

Caused by

Repair

Note:Note: Bleeding may continue through additional coats unless source is removed

Paint School23

DelaminationDelamination(Adhesion failure)(Adhesion failure)

Appearance• Loss of adhesion:

– Intercoat delamination: Between coats– Substrate delamination : Between primer and substrate

Caused by• Primer not compatible with subsequent coat• Contamination of substrate or between coats• Recoating interval too long• Blooming / sweating

Repair• Remove loose paint layer or down to substrate• Recoat

Paint School24

Mud-crackingMud-cracking

Appearance• Cracks occurring during the drying process of the paint• Appearance of the surface of cracked mudCaused by• Particularly for inorganic Zinc applied at a too high film

thicknessRepair• Re-blast to Sa 2½ or grind off• Apply the inorganic Zinc

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Jotun Paint School Course Handouts Page 47

9. AntifoulingAll surfaces exposed to seawater will be "attacked" by marine organisms. When theseorganisms attach and grow, they cause a significant increase in surface roughness. On a ship'shull, this results in greater friction resistance and hence increased fuel consumption. It istherefore extremely important to prevent marine fouling when assessing a ship's fueleconomy. The types of organisms and their growth rates vary with the temperature of theseawater, salinity and the light intensity in the sea. Plant organisms are normally diatoms orgreen/brown algae, whereas the most common animal organisms are Cirripedia (barnacles),bryozoa and hydroids.

The most common way of preventing the fouling of marine structures is to apply apreventative coating or antifouling as we often call it. This contains one or more toxins(biocides) which are normally sufficient to make the antifouling effective against mostorganisms.

Antifouling paint can be divided into three categories: conventional, long life and self-polishing antifouling paints.

1. Conventional antifouling paints – also known as "soluble matrix" antifouling paint, havebeen in use for many years. The main binder is resin, a natural product which dissolves veryslowly in seawater. The Resin is brittle but although these formulations contain variousadditives, this type of antifouling often takes the form of a very weak film and the paint canonly be applied in relatively low film thickness. The effective protection against foulingvaries from 12 to 18 months. 2. Long life antifouling paints are also known as "insoluble matrix". The binder is notcompletely insoluble in seawater. The active components (biocides) and resin are released butthe binder remains on the structure as a porous frame. The porous film left after the biocideshave been released forms a weak substrate for a new coat of paint. It is thereforerecommended that a sealer coat be applied at each dry docking to create a better substrate forthe new antifouling. One risk with this type of antifouling is that year after year, coat aftercoat, many layers of paint are built up. This build up of layers can cause the paint to breakaway from the surface or from earlier coats, which increases the roughness of the hull. Thiscondition is called "sandwich coating" and, after fouling, is the main cause of increasedroughness on a ship's hull. Long-term antifouling paints are effective for about 24 months.

3. Self-polishing antifouling paints – hydrating type are based on a mixture of water-soluble and water-sensitive binders. These react with seawater to form a soft layer whichdissolves relatively easily in water. This type of antifouling was first developed when the needarose for tin-free antifouling paints. The effective life is about 36 months. In today's market, conventional, long-term and self-polishing hydrating antifouling paints arelargely tin-free. 4. Self-polishing antifouling paints – hydrolysing type contain a binder which is initiallyinsoluble in seawater. When the paint film is exposed to seawater, a thin layer on the surfaceof the film absorbs water and a chemical reaction occurs between the binder and the water(hydrolysis). This is the main difference compared with other antifouling paints. The reactionproduct is water-soluble and will slowly dissolve or be washed away. Thus fresh, new

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antifouling paint is constantly being exposed. This results in a linear/predictable rate ofbiocide release which ensures a highly effective antifouling action. This type of antifouling isavailable both tin-free and with tin. Both variants can give effective protection for up to 60months.

One very important reason for using self-polishing antifouling paints is to avoid the"sandwich coating", which often occurs when using conventional or long-term antifoulingpaints. With a self-polishing antifouling paint, the surface will not become porous and it is notnormally necessary to use sealers. When a ship is in dock, the hull is rinsed with fresh waterto remove slime and other contamination, and the new antifouling paint is then applieddirectly onto the old paint film.

Self-polishing antifouling paints are often based on copper with tin and/or other biocides.Those based on tin are restricted in most countries due to the environmental effects in the seaand will be prohibited from use within a few years. Copper-based products are more"environmentally friendly".

Personal notes

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Paint School1

What is fouling ? What is fouling ? (1 of 2)(1 of 2)

Fouling is the settlement and growth ofmarine plants and animals on man-

made structures in the sea

Paint School2

What is fouling ? What is fouling ? (2 of 2)(2 of 2)

There is an estimated 4 - 5000 fouling speciesand these can be classified into:

➨➨ Microfouling– generally referred to as slime, a complex

viscous mixture of bacteria and microscopicorganisms

➨➨ Macrofouling– which includes animals and plants

Paint School3

What is theWhat is theconsequence of foulingconsequence of fouling

On a ship’s hullIncreased fuel consumptionIncreased fuel consumption

On a marine structureIncreased drag Increased drag Heavier load on the structure Heavier load on the structure Structural failuresStructural failures

Seawater pipe systems–– Increased corrosionIncreased corrosion–– Reduced pipe Reduced pipe diametres diametres Pump failures Pump failures

Paint School4

Why do ships needWhy do ships needanti-fouling systems?anti-fouling systems?

Fouling leads to an increase in fuel consumptionof up to 40%, due to the increase in drag resistance

A clean ship sails faster and with less energy

Fouling will eventually damage the primer system

Paint School5

Selection of AntifoulingsSelection of Antifoulings

• Legislation / Environment• Type of ship• Speed• Trade / Voyage factor• Dry-docking interval:

–Conventional antifoulings: 1 - 2 years–TBT-containing antifoulings

(tributyltin): 5 years–TBT-free, self polishing antifoulings: 3 years

Paint School6

Hull roughnessHull roughness

• Permanent roughness– welding seams, valve openings, bulging

plates etc.• Temporary roughness

– flaking, dry spray, cracking, sagging,fouling etc.

Roughness can be divided in two main groups

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Paint School7

Frictional resistance depends on:Frictional resistance depends on:

• The speed of the ship• The area of the underwater hull• The shape of the hull• The roughness of the hull

Hull roughness is the only one of these factors which can be varied to a significant degree

Paint School8

Antifoulings and hull economyAntifoulings and hull economy

Calculation example: Panamax vesselAntifouling

– 7,000 litres at a cost of $ 40,000 - $ 50,000➡ 10% saving represents $ 4,000 - $ 5,000

Fuel cost– 10,000 HP at $ 100 / ton, sailing 250 days a year➡ Would save 5% or $ 100,000 in the same period

➡➡ 20-25 times better return

Paint School9

Application faultsApplication faults

• Typical application faults that increase roughness:– Overspray– Sagging– Dry spray– Paint spatter

• Poor application has a greater ill effect on the dragof a hull than wear and tear

Paint School10

Antifouling Antifouling challengeschallenges

• Main threat on sidebottom is fouling

• Main threat on flatbottom is roughness

Paint School11

Development of AntifoulingsDevelopment of Antifoulings

Influencing factors the past thirty years:

➊ Demands from shipowners for better performance witheconomy

➋ Increased emphasis on surface roughness and hullperformance

➌ Increases in fuel oil prices over the period➍ Technological achievements by many antifouling

manufacturers➎ The trend to extend periods between dry-dockings➏ The increasing awareness of environmental issues

Paint School12

Main types ofMain types of antifoulings antifoulings

1. Conventional Antifouling

2. Long-life Antifouling

3. Selfpolishing Antifouling

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Chapter: Antifoulings

Jotun Paint school Handouts Page 51

Paint School13

The composition of AntifoulingsThe composition of Antifoulings

• Binder• Biocide• Extenders• Pigments• Solvents• Additives

?

Paint School14

Conventional AntifoulingsConventional Antifoulings

• Soluble matrix paints• Rosin as a binder• Approximately 12 months protection• Binders dissolves in water and biocide is released• Often called: Tropic, Super Tropic etc.

NOTE:NOTE:Danger of cracking and flakingNeeds to be quickly immersed in water

Paint School15

Long-life Long-life AntifoulingAntifouling

• Insoluble matrix paints• Only biocides are released• Effective protection is up to 24 months• Leaves weak substrate for subsequent coat• Sealer coat normally required• Binder: CR, Vinyl (possible to add small

amount of colophonium)• Often called Sargasso etc.

Paint School16

Self polishing AntifoulingsSelf polishing Antifoulings

• Predictable performance• Extended dry docking period• Control of roughness and smoothing• No “sandwich coatings” problems• Fouling control due to linear biocide release• Lifetime directly proportioned with dry film

thickness

Paint School17

Selfpolishing AntifoulingSelfpolishing Antifouling with TBT with TBT

• Introduced in the 1970’s• Contains chemically bound organotin• Released by hydrolysis in seawater• In addition, biocides like cuprous oxide

(Cu2O) and organic boosters are used• The rest of the copolymer is water soluble

and is worn off, usually by friction• Reduce hull roughness• No sealer coat required for recoating

Paint School18

Self-polishing Self-polishing AntifoulingAntifouling - Tin free - Tin free

• Blend of water soluble and water sensitivebinders or hydrolysable binders.

• With respect to performance the early ‘ablative’antifoulings have been refined close to thosecontaining tin.

• Not identical to tin based antifouling inperformance yet.

Page 53: Paint School

Chapter: Antifoulings

Jotun Paint school Handouts Page 52

Paint School19

Rel

ease

rat

e (µ

g/cm

2 /

day)

40

30

30

10

1 2 3 Time, years

Conventional A/F

Long life A/F

Selfpolishing A/F

Comparison of release rate of biocide for different A/F-types

Release rate for Anti-Release rate for Anti-foulingsfoulings

Minimum release level for

fouling protection

Paint School20

Why is hydrolysis so important ?Why is hydrolysis so important ?

Because:• Linear erosion rate assures long term antifouling

property• No skeletal layers means good adhesion• Continual smoothing of the surface ensures good

fuel efficiency• Hard film maintains its good appearance

Paint School21

Rules and regulationsRules and regulations

• MEPC approved a draft assembly resolution inNovember 1998 agreeing that:

A complete prohibition on the presence of TBT anti-fouling systems on ship’s hulls to be in place by 1.1.2008

A complete prohibition on the presence of TBT anti-fouling systems on ship’s hulls to be in place by 1.1.2008

The application of all anti-fouling systems containing TBTshould be prohibited throughout the world by 1.1.2003

The application of all anti-fouling systems containing TBTshould be prohibited throughout the world by 1.1.2003

Paint School22

New tin-free technologyNew tin-free technology

SeaQuantum - Advanced tin-free anti-foulingSeaQuantum - Advanced tin-free anti-fouling

Meets the draft IMO regulations for 2003 and 2008Meets the draft IMO regulations for 2003 and 2008

With performance that exceeds what has gone beforeWith performance that exceeds what has gone before

Matches tin-containingMatches tin-containing selfpolishing selfpolishing performance performance

With a track record of success in With a track record of success in newbuilding newbuilding andanddrydockingdrydocking

Based on a unique hydrolysing Based on a unique hydrolysing silylsilyl polymer polymer

Paint School23

• Because linear polishing rateassures long term antifoulingproperty

• Because no skeleton layer meansgood adhesion

• Because continuous smootheningof the surface ensures good fuelefficiency

• Because hard film maintains itsgood appearance

New tin-free technologyNew tin-free technologyWhy is hydrolysis so important?Why is hydrolysis so important?

Newly appliedSteel hull

After exposure in the seaSteel hull

Paint School24

Anti-fouling for Aluminium hullsAnti-fouling for Aluminium hulls

Special requirements:• Must be free from Copper• Must perform at speeds up to 50 knots• Preferably selfpolishing

Can also be used on steel hulls:• When port calls are frequent• When service distances are short• For laid up ships

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Jotun Paint School Course Handouts Page 53

10. Safety, Health and Environment (SHE)In recent years, awareness of SHE-related matters has increased. This is reflected inlegislation and by companies and individuals becoming involved in such matters. At the PaintSchool, we have decided to focus on health problems in connection with the surface treatmentof structures.

General guidelinesDuring the preparation and use of paint, it is important to be aware of the risks associated withthe activity. In brief:

• Follow current legislation from local and national authorities.• Read the safety data sheets for all products. Know the risks and how to protect yourself.• Obtain the necessary training in the use of the products and equipment to be used.• Use the necessary protective equipment to protect the respiratory system, eyes, skin and

hearing.• Inspect all areas where work will take place to reveal possible SHE faults.• Ensure correct storage and handling of products and associated thinners before, during and

after the work. The products should be collected in a specially allocated area.

SafetySafety aspects are particularly important in connection with the use of solvent-based paints.Solvents are flammable and in the right environment and under unfavourable conditions cancause both fire and explosion. Be aware that solvents are heavier than air and will sink downto areas which lie below the painting work.

In general, the following aspects should be checked in connection with painting work.

• Plan the work and co-ordinate this with other activities in the area.• Inspect the area where the work is to be performed. Shut off the areas affected. Remember

areas which are lower than that where the painting is to be performed.• Check the equipment to be used, including safety and protective equipment.• Closed rooms must be declared gas-free before work begins.• Take extra safety precautions when painting in tanks and confined areas: Adequate

ventilation, explosion-proof working lights and equipment, an assistant with a line andadequate breaks in fresh air.

HealthSurface treatment represents a health risk. The risk can however be reduced to a minimum ifthe operators and people in the vicinity of areas where such work is in progress proceed asfollows:

• Read the safety instructions and SHE documentation for the product (safety data sheet)• Follow the instructions given. In particular: use adequate approved protective equipment

e.g. fresh air masks, gloves, protective goggles and anti-static footwear/clothing.

The most serious health risks are associated with the following:

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Jotun Paint School Course Handouts Page 54

Solvents• Irritation of the skin, eyes and respiratory organs• Can be absorbed through the skin. Degrease the skin. Can cause eczema• Negative effects on the liver, kidneys, respiratory organs, blood, central nervous system

and reproductive organs• Can cause headaches, dizziness and fatigue

Epoxy• Irritation of eyes and skin• Causes skin allergy• For sensitive persons: epoxy allergy can be life-long

Isocyanates• Irritation of eyes, skin and respiratory organs• Causes allergy to the skin and respiratory organs• For sensitive people: allergies can be life-long• At high temperature: toxic gases such as free isocyanates can be emitted

Heavy metals: Dust and vapoursMetals harmful to health are mainly: chromium (IV), lead, iron, cadmium, cobalt, copper, zincand nickel. The organs which can be affected (examples of symptoms/effects):• Respiratory organs (metal fever)• Skin (eczema)• Blood cells (anaemia)• Nervous system (fatigue)• Heart (irregular pulse)• Kidneys (reduced function)• Bone structure (accumulation)

DustDust is a factor which must be taken into account both during pre-treatment and sprayapplication. Dust is inhaled through the nose and mouth and can cause lung damage (dustdisease, silicosis) and irritation of the eyes. Dust on the skin can also cause irritationdepending on what the substance contains.

NoiseNoise is primarily linked with steelwork and preparation. Many tools produce noise levelsover 100 decibels. A lower limit for the use of ear protectors is often set at around 80decibels.

Personal notes

Page 56: Paint School

Chapter: SHE

Jotun Paint school Handouts Page 55

Paint School1

Many risks are involvedMany risks are involvedwhen working with paintswhen working with paints

Safety– Explosion and Fire

Health– Manufacturing and Surface treatment

Environment– Emission to air (VOC)– Emission to water (Maintenance)– Emission to soil (Waste handling)

Paint School2

Solvents are heavier than air

• A fire may start in lower areas or compartments• Ignorant personnel below can be affected

Safety hazard: SolventsSafety hazard: Solvents

Paint School3

Safety risk:Safety risk:High pressure equipmentHigh pressure equipment

Surface treatment involves equipment with very high pressures

Never point any high pressure unit at another person or at yourself !!

• Blast cleaning - Mixture of air and particles• Water Jetting - Water up to above 2500 Bar• Airless spray application - Paint

Paint School4

How can we reduce the possibilityHow can we reduce the possibilityfor accidents to happen ?for accidents to happen ?

• Read the Safety Data Sheet and follow thegiven precautions and advices

• Check the surrounding areas for nearbyactivities, particularly welding, machining etc.(remember lower levels)

• Ensure proper ventilation and check thedirection where solvents may move

• Always use approved and sufficient personalprotection equipment of approved type

Paint School5

How flammable is a paint ?How flammable is a paint ?

The “Flash point”“Flash point” tells how flammable a Paint is.

The flash point is the lowest temperatureat which the fumes from the solvents

ignite or explode

Classification:Classification:� Extremely flammable: Flash point below 0 °C� Highly flammable: Flash point between 0 and 21°C� Flammable: Flash point between 21 and 55 °C

This information can be found in the Safety Data SheetPaint School6

Precautions when paintingPrecautions when paintingin confined spaces.in confined spaces.

• Ensure good ventilation• Exhaust points for fumes / solvents must be close

to the bottom• Start application from the bottom and up• Always use non-sparking tools• Use antistatic clothing with hood• Use masks with air supply• Use boots and gloves• Safety lines• Sufficient rest periods

Never smokeor use naked flames !

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Chapter: SHE

Jotun Paint school Handouts Page 56

Paint School7

SymbolsSymbolsFire and explosion hazardsFire and explosion hazards

These symbols can be found inSafety Data Sheets and on the paint tin label

Explosive Oxidizing Extremelyflammable

Highly flammable

E O F+ F

Paint School8

SymbolsSymbolsHealth hazardsHealth hazards

These symbols can be found inSafety Data Sheets and on the paint tin label

Very Toxic Toxic Corrosive Harmful Irritant

T+ T C Xn Xi

Paint School9

Types of information to be found inTypes of information to be found in the safety data sheet (16 points). the safety data sheet (16 points).

1. Identification of the company2. Composition and ingredients3. Hazard identification4. First aid measure5. Fire fighting Measures6. Accidental release measures7. Handling and storage8. Exposure control and personal

protection

9. Physical and chemical properties10. Stability and reactivity11. Toxicological information12. Ecological information13. Disposal considerations14. Transport information15. Regulatory information16. Other information

Paint School10

Evaporation of solvents duringEvaporation of solvents duringapplication of an objectapplication of an object

Area: 20.000 m² Dry Film thickness: 300 microns

0

1000

2000

3000

4000

5000

Mastic Tar Epoxy Alkyd CR82 % 65 % 50 % 40 %

Litres of Solvents

Vol. % Solids

Paint School11

General precautions forGeneral precautions forsurface treatment surface treatment (1 of 3)(1 of 3)

Before the work starts• Do not start the work without proper training or experience• Know all safety routines and where to find

necessary equipment if an accident should occur• Read and understand all Safety and Technical Data Sheets• Know all the hazards involved (R phrases)• Know all protective measures requires (S phrases)• Availability of appropriate, personal protection equipment• Evaluate the work place regarding - Other nearby activities, warning signs,

mixing station, first aid kits, ventilation, housekeepingPaint School12

During work• Always use appropriate, approved

personal protection equipment• Use the tools and equipment correctly to avoid

injuries to others or to yourself• Keep all containers / tins closed• The work can be exhausting: Take sufficient rests• Keep the work place tidy during the work

General precautions forGeneral precautions forsurface treatment surface treatment (2 of 3)(2 of 3)

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Chapter: SHE

Jotun Paint school Handouts Page 57

Paint School13

After work• Close all Containers / tins• Clean the equipment properly• Store unused paint and thinners safely (Paint store)• Throw waste in designated containers. (Hazardous

waste)• Clean the personal protection equipment

and store it properly to avoid contamination• Clean yourself with water and cleaning cream

General precautions forGeneral precautions forsurface treatment surface treatment (3 of 3)(3 of 3)

Paint School14

Filter typesFilter types

DustP1: Lowest degree of protectionP2: Medium degree of protectionP3: Highest degree of protection

Gas from organic solventsA1 Lowest degree of protectionA2 Medium degree of protectionA3 Highest degree of protection Other types might be

required for productsclassified as corrosive.

Paint School15

Health Health hazardshazardswhen using paintswhen using paints..

BindersBinders• Skin contact.• Particularly Epoxy, Amines and Isocyanates may

cause skin irritation and Allergic reactions

Other constituents:Other constituents:• Tar, Heavy metals

• By inhalation• Skin contact• Ingestion

Solvents: May enter the body in three ways:

Paint School16

Health Health hazardshazards from fromsolventsolvent exposure exposure

Acute effects• Headache• Abnormal tiredness• Dizziness• Nausea

Long term effects• Irritability • Loss of memory• Organ damages

(kidneys, liver, CNS)• Reduced reaction ability• Reduced evaluation ability

Skin irritations• Eczema• Dry and cracked skin

Paint School17

Health hazard:Health hazard:inhalation of solventsinhalation of solvents

The most dangerous hazard• Solvents will be transported by the blood stream to internal

organs of the body.• Amount absorbed and the effect on the body will depend

on: Type of solvent, period of exposure, concentration andwork load.

• May cause damage to: Central nervous system, respiratorysystem, liver, kidneys and reproductive systems,

Protective measures:Proper ventilation.

Use approved, protective mask

Paint School18

Health hazard:Health hazard:Skin contact with solventsSkin contact with solvents

The most frequently occurring health effects• Causes:

- Reddening - Swelling - Drying and cracking of skin - Absorption through intact skin: Some, like Xylene - Absorption through damaged skin: Several, like White Spirit

Protective measures: Avoid direct contact

Protective clothes, gloves and boots

Page 59: Paint School

Chapter: SHE

Jotun Paint school Handouts Page 58

Paint School19

Health Health hazards whenhazards whenworking with working with EpoxiesEpoxies..

Hazards :� Eczema and allergic reactions on the skin� Liquid Epoxies with low molecular weigths (below 700) are most likely to give an allergic reaction� An allergic reaction to Epoxy is irreversible.� Hyper-sensitive persons must stay away from epoxies.

Protective measures� Protective clothes covering the whole body and gloves� Proper cleaning with water, soap and cleaning cream� Use disposable overalls

Paint School20

Health Health hazards whenhazards whenworking withworking with tartar containing paints containing paints..

Hazards� The main hazard with tar containing paints is the risk for

developing cancer, especially when exposed to strong sunlight� Long term exposure to vapours may damage internal organs,

cause heritable genetic defects and birth defects� Short term exposure to fume and vapours may cause irritation

to nose, throat and eyes� Splashes to skin causes irritationProtective measures� Protective mask to avoid breathing vapours� Protective clothes covering the whole body and gloves

Paint School21

Health Health hazards when workinghazards when workingwith paints containing with paints containing IsocyanatesIsocyanates..� The monomer is more volatile than the pre-polymer and is

therefore more dangerous� Isocyanates are found in Polyurethane paintsHazards� Irritation of eyes skin and airways� Sensitization by inhalation and skin contact� AsthmaProtective measures� Protective mask to avoid breathing of vapours� Protective clothes covering the whole body, boots and gloves

Paint School22

Some times used in pigments, additives or driers.Hazards (Metal fumes,dust from hot work)� Zinc. Dust and fumes: Zinc fever, chills, coughing, irritation� Copper. Fumes: Metal fever and chills� Lead. Dust and fumes. Damage blood cells, Anemi, skeleton,

reduced fertility and central nervous system� Chromium. Dust and fumes: Sensitisation, cancer� Nickel / Cobalt. SensitisationGeneral Protective measures� Protective mask to avoid breathing of vapours� Protective clothes covering the whole body, boots and gloves

Health Health hazards when workinghazards when workingwith paints containingwith paints containing heavyheavy metals metals..

Paint School23

• Antifoulings are generally looked upon as Toxic• Some antifoulings contain Tin• Tin may cause irritation to skin and eyes the central

nervous system and effect the immune system

General Protective measures� Protective mask to avoid breathing of

spray mist / droplets� Protective clothes covering the whole body,

boots and gloves

Health Health hazards when workinghazards when workingwith with antifoulingsantifoulings..

Paint School24

How dangerous is aHow dangerous is achemical or a paint ?chemical or a paint ?

Different persons will respond differentlyIn general the hazard will depend on:

The concentrationand risk of exposure

The toxicity and amount

of the compound

The contact period with the chemical

Page 60: Paint School

Jotun Paint School Course Handouts Page 59

11. Corrosion

What is corrosion?

To give materials satisfactory protection against corrosion, it is important to understand whatcorrosion is. Only once we know when, how and why a material corrodes (rusts) can wespecify the right material and give the material a cost-effective protection.

Corrosion is defined as "a material’s reaction with the surrounding environment during theformation of corrosion products". From this definition, it is clear that it is not enough toknow the properties of the material, we also need knowledge of the exposure environment.This means that we need to know how corrosive the environment surrounding the material is.To illustrate the different material properties, consider the following example: gold will notcorrode in seawater and therefore we call this an inert material in this environment. Zinchowever is far from inert. Similarly a particular material will have a totally different longevityin two different environments: unprotected steel corrodes quickly in seawater but will bealmost everlasting in a dry indoor atmosphere.

The corrosion process

The corrosion process is caused by the supply of energy to metals when they are producedand processed. This is an undesirable energy state and the metal will try to return to its naturalcondition. This can involve the material dissolving into metal ions and electrons. For such areaction to occur, the metal must form part of a corrosion cell. A corrosion cell consists oftwo different materials connected together via a conductive electrolyte and a metal conductor.A conductor can be another conductive material or it can be a direct contact between the twometals. The conductive electrolyte can for example be seawater or condensation with someform of contamination or salts which make the condensation conductive.

If we regard the corrosion process as an electrical circuit, it is easy see that we can stop or atleast reduce the corrosion by either breaking the electrical circuit or by increasing theresistance in the circuit. This is the principle behind the use of many paints as corrosionprotection. When paint is applied to the metal, we apply an insulating layer and it becomesmore difficult for the conductive ions in the electrolyte to reach the surface of the metal. Theohmic resistance in the circuit increases. Another method is to change the surroundingenvironment. We can for example prevent condensation forming by changing the temperatureof the metal or by ensuring better ventilation.

Corrosion types

There are many different forms of corrosion. Although we will not discuss all of them, weshould briefly mention the two most common types on steel structures: galvanic corrosion,general corrosion and crevice corrosion.

Galvanic corrosion occurs when two different alloys are connected together in an electricalcircuit, as described for corrosion cells. In such a circuit, it is always the most negative metalwhich corrodes. This metal is called the base metal or the anode in the circuit. The noble

Page 61: Paint School

Jotun Paint School Course Handouts Page 60

metal or cathode will actually acquire a certain degree of protection (see cathodic protection).Typical examples of galvanic corrosion are aluminium which corrodes when connected tosteel or a cast iron valve which is connected to an aluminium-brass pipe.

In principle, general corrosion is very similar to galvanic corrosion except that the corrosionprocess occurs on one metal only. The galvanic cell occurs when either various alloy elementsor contaminants are present in the metal or the metal surface is uneven. The corrosion willoccur on the most base elements on the alloy surface.

Crevice corrosion is a type of corrosion which is mostly found on passive materials such asstainless steels. The attack takes place in narrow gaps or crevices. Critical crevices forinitiation of corrosion are between plates, pores in welds, between gasket and flange in pipesystems, under various types of settlements (marine mud) and contamination (paint splashes).The reason for the attacks is that the environment inside the crevice is different from theenvironment outside. A corrosion cell will be formed between the two areas. A ondition thatwill increase the risk of attack even furter is the presens of aggressive ions such as chloridesfound in seawater. Once initiated the crevice corrosion attack may propagate at a very highspeed and cause rust penetration within a surprisingly short period of time.

Personal notes

Page 62: Paint School

Chapter: Corrosion

Jotun Paint school Handouts Page 61

Paint School1

Definition of CorrosionDefinition of Corrosion

Corrosion is a reaction between

Materialand

Surrounding environment

under formation of corrosion products

Paint School2

Production andProduction anddegradation of steeldegradation of steel

Plates, pipes,profiles, etc.

Energy

Manufac

turing

Water /humidity

Oxygen

Raw materialIron ore Rust

Reaction between the material and the surrounding environment takes place

The presence of water / humidity and Oxygen is a pre-requisite for corrosion of steel

Paint School3

How is rust formed ?How is rust formed ?

Painted surfaceexposed to humidity

The water molecules penetrate the paintDue to osmotic forces blisters are formed

The blisters break andcorrosion is initiated

Paint School4

Freely corroding steelFreely corroding steel

Electrolyte (Water or soil)

Steel

Cathode CathodeAnode

Paint

Paint School5

Pre-requisites for corrosionPre-requisites for corrosion

• A Cathode:The noble metal / alloy (or part of metal)

• An Anode:The less noble metal / alloy

• An electrical connection between the two metals.Conducting electrical current (by electrons)

• An electrolyte:Conducting electrical current (by ions)

A galvanic cell consists of:

Paint School6

AA galvanic cell galvanic cell

In seawater, a calcareous deposit is formed on the steel surface

2 e

Zn = Zn + 2 e

Cathode:Steel Anode:

ZincO2

½ O2 + H2 O + 2e = 2OH

2+ -

- -

-

-

Page 63: Paint School

Chapter: Corrosion

Jotun Paint school Handouts Page 62

Paint School7

Aluminium Zinc Steel

Protective Iron oxide

In a strong alcaline environment Aluminium and Zinc will corrode rapidly, while steel will be passive

Corrosion speed differ whenCorrosion speed differ whenexposed to the same environmentexposed to the same environment

pH > 10

Paint School8

Galvanic potentials in seawaterGalvanic potentials in seawater

Paint School9

Steel inSteel in Seawater SeawaterPotentialPotential versus versus Zinc Zinc & Ag/Ag & Ag/Ag ClCl ref. ref. electrodeselectrodes

Rapid corrosion

General corrosion

Some corrosion

100% Cathodic protection

Overprotection

Possible coating damage

Increasing polarisation

Ag / Ag Cl Zinc

+ 0.50

- 0.25

+ 0.0

+ 0.25

- 0.55

- 1.30

-1.05

- 0.80

Potentials in volt

- 0.60

- 1.35

-1.10

- 0.85

Cu / CuSO4

Paint School10

How to measure the corrosionHow to measure the corrosionpotential of a structurepotential of a structure

+ -

Reference electrode

Volt meter

Structure

Sea water

Paint School11

Elements influencing theElements influencing thecorrosion speed of metalscorrosion speed of metals

• Temperature• Salinity• Oxygen content• Water velocity• Acidity (See below)• Type of electrolyte ( e.g. cargo or chemicals)• Content of contaminants / pollution that

promotes corrosion• Micro-organisms.

Submerged materials

Paint School12

Neutral

Acidic

Alcaline

pH-scalepH-scale

Page 64: Paint School

Chapter: Corrosion

Jotun Paint school Handouts Page 63

Paint School13

ParametresParametres influencing the corrosion influencing the corrosionspeed. Atmospheric corrosionspeed. Atmospheric corrosion

• Humidity• Temperature• Concentration of salts• Amount of air pollution,

including acid rain, soot and dust particles

Paint School14

Apart from using paint and CP:Apart from using paint and CP:How to protect against corrosion ?How to protect against corrosion ?

• Good design• Avoid corrosion traps• Improved accessibility - maintenance• Proper materials selection• Insulate between dissimilar materials• Change the surrounding environment• Remove water / humidity• Apply metallic coatings• Use corrosion inhibitors (closed systems)

Corrosion protection can be achieved in many waysCorrosion protection can be achieved in many ways

Paint School15

Avoid stagnant water atAvoid stagnant water atbottoms of tanks and containersbottoms of tanks and containers

Unfortunate Better Best solutionx

x x

Paint School16

CorrosionCorrosionProperties of the materialsProperties of the materials

• All materials have their strong sides• But, they also have their weak points

Knowledge is required for selecting the correct material for a given application

Paint School17

Most frequently occurringMost frequently occurringtypes of corrosiontypes of corrosion

On carbon steel• Uniform corrosion• Uneven corrosion (deep pits)• Galvanic corrosion• Stress corrosion cracking

Paint School18

Most frequently occurringMost frequently occurringtypes of corrosiontypes of corrosion

Stainless steels• Crevice corrosion• Pitting corrosion• Stress corrosion cracking

Titanium• Hydrogen embrittlement

• Fatigue

Aluminium• Pitting corrosion• Galvanic corrosion

Copper based alloys• Erosion corrosion

Page 65: Paint School

Chapter: Corrosion

Jotun Paint school Handouts Page 64

Paint School19

Steel with mill scaleSteel with mill scale

Outdoor exposure• The mill scale cracks• Corrosion will develop on the steelMill scale is more noble than steel

Mill scale Corrosion

Steel Steel

Paint School20

Crevice corrosion occurs underCrevice corrosion occurs underpaint spillage or platespaint spillage or plates

StainlessStainless Steel Steel

PaintPlate

Corroded areas

Ingress of seawaterSeawater

Crevice corrosion occurs in narrow gaps where the oxygen concentration is lower than

on the freely exposed part of the material

Paint School21

Galvanic corrosion is to a large extentGalvanic corrosion is to a large extentdetermined by the conductivity of the electrolytedetermined by the conductivity of the electrolyte

Anode Cathode

Corroded area

The corrosion attack decreases with increasing distance from the cathode due to an increased ohmic resistance

Electrolyte (Seawater)

Paint School22

Pitting corrosionPitting corrosion

• Pitting corrosion is a localised attack on a material normally protected by a passive film• The passive film may be destroyed mechanically or by aggressive ions in an electrolyte• Severe corrosion may take place beneath the passive layer

Seen from above Cross section

Stainless steel

Passive layerPitting corrosion

Paint School23

Corrosion fatigueCorrosion fatigue

No. of dynamic cycles

Load

No failure above line

Fatigue only

Corrosion fatigue

Corrosion Fatigue is a combined effect of an aggressive environment and dynamic loads on a structure

Paint School24

Stray current corrosionStray current corrosion

- +Welding transformer

Quay

Corrosion

Stray current

To earth

Pontoon

Seawater

Welding on board

Page 66: Paint School

Jotun Paint School Course Handouts Page 65

12. Cathodic Protection

Basic conditions

Cathodic protection (CP) is one of the most common forms of corrosion protection. Tounderstand how this method works, you need to be familiar with a few basic facts. The first isthe mechanism behind the corrosion process (see the section "Corrosion"). Remember that thevery occurrence of the corrosion process means that when a metal corrodes (rusts), the metalbreaks down into ions and electrons are released.

It is also necessary to understand what an electrochemical cell (corrosion cell) is. This is aconductive circuit which consists of a noble metal (cathode) and a base metal (anode) inmetallic contact with each other. In addition, the metals must be in contact with each other viaa conductive electrolyte (for example seawater). In such a circuit, it is always the anode whichcorrodes, while the cathode will be protected.

Which metal will corrode in a cell ?

When two metals are connected together, we can predict which will corrode and which willbe protected. This is due to the electrochemical voltage level of the metal, or corrosionpotential. The potential for a metal can be measured by putting the metal in seawater andmeasuring the voltage between the metal and a reference electrode. When we have measuredthe potential of several metals, we can classify them. The most noble is placed at the top ofthe list and the most base at the bottom. This classification is called the ‘Galvanic series’. In aconnection between two metals, the most negative metal will be the anode whilst the metalhigher up in the table will be the cathode.

Principle of cathodic protection

Cathodic protection is based on preventing a metal from dissolving. By ensuring thatelectrons cannot be released from the metal we want to protect, the corrosion can be limited orstopped. This is done by connecting a more negatively charged metal (e.g. aluminium) to themetal we want to protect (e.g. steel). Aluminium will release electrons more readily and willhave enough power to propel the electrons into the steel and thus prevent dissolution.Aluminium is therefore the anode and will corrode instead of the steel. The aluminium issacrificed, hence the name sacrificial anode.

When the negatively charged electrons enter the steel, the steel will of course have a morenegative potential than it has in its free state. It is this change in potential which protects thesteel. To ensure protection, the steel must fall below a certain negative potential level. Thislevel is called the protection potential and is specified as a design criterion. The protectionpotential is normally of the order of -800 mV relative to a silver/silver chloride referenceelectrode.

An anode can only release a certain number of electrons before it is consumed. To ensure thatthe anodes work as long as necessary, we must calculate how many anodes are required.These calculations are called ‘designing a cathodic protection system’. A design requires

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Jotun Paint School Course Handouts Page 66

knowledge of some important parameters. The most important ones are the area to beprotected, the type of material to be protected, the type of anode to be used, the lifetime of thesystem and the area of the structure which has been painted. A painted structure requiresfewer anodes than an unpainted one.

Finally: cathodic protection can be achieved by a forced voltage system. These systemssupply DC current to the steel in the same way as anodes.

Personal notes

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Chapter: Cathodic Protection

Jotun Paint School Handouts Page 67

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Corrosion of a metal or alloyCorrosion of a metal or alloy

• Corrosion is a reaction between the metal and the surroundingenvironment

• The corrosion rate depends on the properties of the metal andthe corrosivity of the environment.

• Corrosion is dissolution of the metal, among other thingsinvolving the release of electrons:

2+Fe →→→→ Fe + 2e

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How to protect a structureHow to protect a structure

Corrosion Protection can be achieved by :• Sacrificial Anode Cathodic Protection System• Impressed Current Cathodic Protection System

Both systems supply electrons to the structure.The structure will become more negative and metal

dissolution will be prevented

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• Zinc– Noranode– Coral Z

• Aluminium– Coral A– Coral A high grade

• Magnesium

Type ofType of sacrificial anodessacrificial anodes

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MarineMarineObjectsObjects to be to be protectedprotected::

• Ships• FPSO / FSU• Mobile rigs• Floating dry-docks• Barges

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Offshore and Offshore and industryindustry (Norwegian (Norwegian sectorsector).).ObjectsObjects to be to be protectedprotected::

• Offshore platforms– Fixed/floating– Concrete/steel

• Subsea installations– Templates/manifolds/

modules.• Subsea pipelines

• Harbour facilities– Piles– Sheet piles

• Buried tanks andpipelines (onshore)

• Above ground storagetanks

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TheThe principle principle of cathodic of cathodic protection protection..potentials vspotentials vs. different reference. different reference electrodes electrodes

+ 500

+400

+300

+200

+100

0

- 600

- 700

- 800

- 900

- 1000

- 1100

Freely corroding steel

Mixed potential

Freely corroding Zinc

mVZn

Cu /

CuSO4

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Chapter: Cathodic Protection

Jotun Paint School Handouts Page 68

Paint School7

Cathodic Cathodic ProtectionProtectionSteel Steel protected protected by a by a sacrificialsacrificial anode anode

Electrolyte (Water or soil)

Cathode Anode

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Rapid corrosion

General corrosion

Some corrosion

100% Cathodic protection

Overprotection

Possible coating damage

Corrosion potentialsCorrosion potentials in in seawaterseawaterZincZinc, Ag/Ag , Ag/Ag ClCl and and CuCu/CuSO/CuSO4 R4 Reference eference electrodeselectrodes

Ag / Ag Cl Zinc

+ 0.50

- 0.25

+ 0.0

+ 0.25

- 0.55

- 1.30

-1.05

- 0.80

Potentials in volt

- 0.60

- 1.35

-1.10

- 0.85

Cu / CuSO4

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ReductionReduction of of corrosion corrosion rate of steel by rate of steel bycathodiccathodic protection protection.. Moving seawater Moving seawater

Corrosion rate(per cent)

Free corrosion100

50

10

Full cathodic protection

-600 -650 -700 -750 - 800 -850+500 +450 +400 +350 +300 +250

mVCu / CuSO4Zn

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MarineMarineDesign criteriaDesign criteria

• Design lifetime• Coating system and condition• Current density (Coating type and

damages)• Electrolytic resistivity• Environmental conditions / impacts• Ballasting period.

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ProtectiveProtectiveDesign criteriaDesign criteria

• Design lifetime• Coating system and condition• Protection potential• Anode capacity• Electrolyte resistivity• Environmental conditions/impacts

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Current density requirementCurrent density requirementdependsdepends on: on:

A. Environmental parameters• Sea water composition and

salinity• Sea water temperature• Resistivity of sea water• Sea water flow velocity• Other factors, marine growth

B. Steel surface• Painted / not painted• Steel temperature• Coating system, if any• Condition of coating

system

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Chapter: Cathodic Protection

Jotun Paint School Handouts Page 69

Paint School13

Sacrificial anode material selectionSacrificial anode material selection

Main TypesMain Types• Zinc• Aluminium• Magnesium

Anode material selectionAnode material selection• Chemical composition• Electrochemical

performance- Anode potential- Stable current- Consumption

• Anode corrosion pattern• Price• Class requirements

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ComparisonComparison of cathodic of cathodic protection protection systems systemsgeneralgeneral advantagesadvantages::

Sacrificial anode systems• Simple, reliable and free

from in-service operatorsurveillance

• System installation issimple

• Low installation cost for short term protection

Impressed current systems• Flexibility under widely

varying operating conditions• Weight advantage for large

capacity, long life systems• Low friction (reduced sea

water drag)• Low life cycle cost (LCC)

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ComparisonComparison of cathodic of cathodic protection protectionsystems general systems general limitationslimitations

Sacrificial anode systems• Large weight for large

capacity, long life systems.

• Response to varyingoperating conditions islimited.

• Hydrodynamic loadings canbe high (Seawater drag)

Impressed current systems• Relative complexity of

system demands high levelof design expertise.

• In-service operatorsurveillance required.

• Vulnerable to componentfailure or loss of power.

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Why chooseWhy choose an ICCP system on hull an ICCP system on hull

• Smooth hull, no drag• Flexible dry-docking intervals• Low cost for long term operation• Long lifetime, minimum of maintenance• No welding required at dry docking• No risk of damaging internal Paint systems• Fully automatic corrosion protection

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Why chooseWhy choose a SACP system on hull a SACP system on hull

• Simple installation

• Maintenance free between dry docking

• Low cost for short term operation

• World-wide availability

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ShipShip hull: hull: Current density Current density at atdifferentdifferent paint paint damage damage

Current density, mA/m²20 40 60 80 100 120 140 160 180

100

80

60

40

20

0

Paint damage, %

Anodes ICCP

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Chapter: Cathodic Protection

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PrinciplePrinciple : : Effect Effect of of using using CP CPCorrosion Curves depend on - Coating condition - CP-design

Coating breakdown

CP installed

CP and coating at newbuilding

Time

Corrosion

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Corrosion in broken blisterCorrosion in broken blisterPassivation Passivation by CPby CP

Paint

Steel

Rust

Without Cathodic Protection

Paint

Steel

With Cathodic ProtectionAnodeAnode current

Seawater

Seawater

Calcareous layer

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ShipsShips hull: hull: Current density Current density as asfunctionfunction of coating of coating breakdown breakdown

Coating breakdown Current density 2 - 5 % 10 mA/m2

5-10 % 15 mA/m2

10-15 % 20 mA/m2

15-20 % 30 mA/m2

20-25 % 40 mA/m2

25-30 % 50 mA/m2

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Sacrificial anode systemSacrificial anode system

➊ Aluminium alloy anodes➋ Zinc alloy anodes (technically equal)

Aluminium is recommended prior toAluminium is recommended prior toZinc because:Zinc because:

☛ Aluminium anode weight is approx. 1/3 of Zinc☛ Total price for equal protection: Al. anodes

approx 1/2 of Zinc anodes☛ Lower installation costs due to weight difference

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Cathodic protectionCathodic protection❶ ICCP - Impressed Current❷ SACP - Sacrificial Anodes❸ EAF - Electrolytic Antifouling System for

seawater systems (CUPROBAN)❹ Slip ring arrangement for propeller shaft

Coatings and Cathodic ProtectionCoatings and Cathodic Protection

➡➡ The Single Source SolutionThe Single Source Solution

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Location of Pitguard anodesLocation of Pitguard anodes

Web frame

Web frame

Tank bottom

SeawaterAnode

Waterlevel