marine coating assigment
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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
-
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
5
10
15
20
25
30
35
40
-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
THANK YOU
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