Assignment : Marine Coatings &

Protective Coatings Prepared by:

ABDUL JABBAR KHAN

Main function of coatings is toprotect steel structures against corrosion and against chemicals

• Marine and Offshore• Industrial Steel Structures• Industrial Maintenance• Tanks• Transportation

– Railcars – Large vehicles– Sea containers [China]

Key Market Segments in Europe

Petrochemical plants10%Public Utilities

11%

Oil & gas production & transmission

11%

Bridges & infrastructure13%

Water and sew age7%

Food & beverage plants8%

Pulp and paper3%

Others7% Marine

30%

Worldwide consumption of anticorrosion coatings estimated atca. 1.1 Millions MT, with a value of ca. $ 5 Billions in 2001.

M&PC coatings represent 4% of the global coatings volume, but 8-9% of the total value.

.The role of coatings is to protect against corrosion each part of ships, which are continuously exposed to severe conditions, i.e. sea water immersion, splashes of sea water, UV rays

– maintain the value of the assets– ensure vessel safety– protect cargoes, e.g. grain or liquids– – Ballast tanks–

Ballast tanks

– Water ballast tanks – Under water hulls and sides– Cargo tank linings– Cargo holds – Boot-topping and splash

zones– Topsides and external

superstructures– Offshore oil drilling

platforms

Key Performances requirements

Resistance to corrosion

Chemical resistance

Mechanical resistance, e.g. abrasion

Weatherability

Consumption of High-Performance Anticorrosion Coatings by Resin Type in Europe

20%

7%

6%

2%

5%

2%10% 3%

45%

Epoxy

Urethane(aliphatic) Urethane(aromatic) Inorganic Zinc

Vinyl

Acrylic

ChlorinatedRubberAlkyd

Other

Source: SRI report 2001

Epoxy Resins are essential raw materials for Marine & Protective Coatings. Epoxy systems offer an outstanding balance between performances

[durable corrosion protection] and costs.

Top Coat: Appearance & Protection against UV-lightMid Coat: Barrier Protection effect. Intercoat

adhesionPrimer: Corrosion protection & Adhesion

Metal Substrate

Epoxy coating

Epoxycoating

Epoxy, PU, Alkyd, AcrylateEpoxy, PU, Alkyd, Acrylate

Basic Composition of Paint

Solvents (Liquids)

PigmentsAdditives

Resins (Binder)

PaintPigments: These are powders which impart

colour and hiding power to paintsSome pigments have mainly decorative

function while others have protective function

Few pigments have very special function, e.g cuprous oxide, for anti-fouling paint ; leafing (flake) aluminium reflects sunshine and reduce heating.

Paints:Paints are used to protect metals, timber or plastered surfaces, brick work and concrete work from the corrosive effects of weather, heat, moisture or gases etc and to improve their appearance. Composition of the paints can be easily adjusted in the process of their manufacture, depending upon the purpose for which they are required and quality of the work required.

CONSTITUENTS/ COMPOSITION OF PAINTS:Paints essentially contain a base which provides body, there is a carrier, also known as vehicle in which the base is dissolved, and it is the carrier which helps the base to spread all over when applied. The pigments are also added to give the desired colours. Some common examples of substances used as base in paint are zinc white, white lead, red lead. Common substances used as carrier in the paints is such as, water (in water paints), linseed oil and poppy oil etc.

Besides these essential ingredients, several other substances are added, such as fillers to give bulk to the paint without affecting its properties and to make it economical, solvents or thinners which dissolve other constituents and make the paint thin and driers which help in rapid drying, setting and hardening of the painted surface. Some commonly used fillers for paints are chalk, silica and charcoal, commonly used solvents are turpentine oils, petroleum sprit, commonly used driers are red lead, litharge and manganese sulphates etc.

USES OF PAINTS:The main functions performed by paints are:It is used to give a high-class finish,It is used to give attractive colours,It is used to give pleasing surfaces design and

appearance,It is also used to protect the material from

atmospheric effects,To protect various substances from corrosion,To protect wooden articles from wet-rot and

many other types of defects,To make the materials long lasting.

PROPERTIES OF GOOD PAINTS :The main properties of a good paint are as

follows:It should give a thin and uniform coating.It should be hard and durable on drying.The painted surface should not crack on drying.It should be resistant to weathering and

corrosive action.It should be water-repellent (except water

paints).It should have good spread.It should have good adhesive power. It should

give a good finish with attractive colour, design and appearance.

The colours should be fast and permanent.It should be cheap and economical.

Categorization of coating deficiencies: While coating failures may occur for number of reasons, they can generally be categorized into four main groupings: 1.Coating manufacturer related or caused 2.Owner/specifier related or caused 3.Coating applicator related or caused 4.Environmental service related or caused.

Coating Defects-Blistering

Coating Defects-Checking

Coating Defects-Cissing

Coating Defects-Cracking and Detachment

Coating Defects-Edge Failure

Coating Defects-Wrinkling

Coating Defects-Weld Failure

Coating Defects-Adhesion Failure

Surface preparation Blast cleaningPicklingFlame cleaningPreparation by handHydroblasting

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Blast CleaningMost efficient method of surface preparationTwo types of Blast equipment:

a. an impeller wheel plant where abrasives are thrown at high velocity against the metal surface. Self contained and collect dust and re-circulate clean abrasive – plant useb. a nozzle type where a jet of abrasive impinges on the metal surface – fitted with vacuum dust recovery equipment

Cast iron and steel grits or steel shots is preferred for metallic abrasive but non-metallic abrasives are also use.

After blasting, brush clean surface and apply a priming coat

Blast Cleaning Standards

Sa 2.5

Sa 3

Sa 2 Sa 1

PicklingImmersion of metals in an acid solutionTo remove mill scale and rust from surfaceAfter immersion in acid , metal requires

thorough hot water rinse Treatment followed by application of a priming

coat

Materials

Flame CleaningTo remove mill scale and rust from surfaceDoes not entirely remove the mill scale and rustUseful for cleaning plates under inclement

weather condition, the flame drying out the plate

Materials

The terms water washing (usually used to remove salts, slimes and light fouling from vessels in dry dock) and hydroblasting (used to remove rust and paint) can easily become confused.  To clarify the situation, the following pressure guidelines are given:

Hydroblasting / Water Jetting

Painting Procedures and PrecautionsSuccessful application of paint requires correct

technique during painting and suitable conditions during which the application takes place

Painting should take place in warm dry weather but not in direct sunlight

Presence of moisture in air or on metal surface may damage paintwork or slow down the curing process

Painting Procedures and PrecautionsPrincipal methods of paint application are the

airless spray, the air assisted spray, the roller and the brush

Brush and roller is employed when the surface is rough and small inaccessible places are to cover

The methods is slow, labour intensive and difficult with certain type of paints

Air-assisted spray has been replaced by the airless spray technique

Airless spray is the fastest and clean method.Dry film thickness of up to 300 microns

possible

Painting Procedures and PrecautionsThroughout the preparation and painting of a ship,

the need for good, safe, suitable means of access is paramount

Freedom of movement to maintain appropriate distance for paint spraying is essential

Safety is required with paints.. toxic/poisonous, flammable and irritant to skin.

Adequate ventilation and protection necessary Avoid possibility of fire and explosion

0

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35

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-10 -5 0 5 10 15 20 25 30 35 40

Temperature, °C

68 % Solids

60 % Solids

100% solids

Dry

ing

tim

e H

ou

rs

82% Solids

Drying time of epoxy coatings severely affected by temperatureDrying time strongly influenced by solids content Note: More reactive curing agents generally employed in winter systems

Drying time versus temperature of commercial coatings

Anti-Fouling PaintsThe ‘new’ anti-fouling technology - organometallic

polymer system (Self-polishing co-polymer)It incorporates an organotin toxicant.A large number of organotin polymers have been

synthesized.The coating becomes smoother with passage of

time since turbulent flow of sea water selectively removes the ‘peak’ of the anti-fouling coating where it covers roughness in the underlying hull surface.

As the toxicant is an integral part of resin matrix, the length of time during which it is active depends on the thickness of the layer applied.

Materials

Underwater surface condition of a vessel to which a high quality, self-polishing antifouling paint was applied 30 months earlier.

Self-polishing antifouling paints applied to the underwater surface of an oil tanker.

END OF SLIDE SHOW

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