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Corrosion theory

1. What kind of process is corrosion?

Corrosion is an electrochemical process which results from an anodic reaction

and at least one cathodic reaction.

2. What factors influence the rate of corrosion?

Factors that influence the rate of corrosion as follows.

A) Variation in oxygen content on the steel surface(wet/dry)

B) R.H % (Above 60% is critical)

C) Presence of impurities in the air (acid, alkalis, salt etc.)

D) Higher nobility metals in contact with the steel.(Mill scale)

3. What particular problem related to splash zone?

1.Rapid change in Oxygen content.

2.Moisture in the atmosphere is critical ie above60%

3Wave Impact and Erosion.

4.Growth of Marine life.5.Heavily laden salt atmosphere.

6.Mechanical and Boat damage.

7.Access to the Working area.

4. What is mill scale and why it is particular problem when attempting to protect steel?

Mill scale is an oxide of iron produced when the steel is manufactured.

It is a result of the white hot steel into contact with air and forming oxide composed

Of three layers, FeO nearest steel, Fe3 O4 then Fe2O3 on the outside.

Mill scale thickness ranges from 25 microns to 100 microns.It is essential for mill scale to be removed from steel surface during blast cleaning for

the following two reasons.

Mill scale is more noble than steel and when parts of the mill scale break away the

exposed area of steel ie anode will sacrifice themselves to preserve the more noble

surrounding mill scale ie cathode.

If painted over the mill scale which is loosely adhering and flaky will leave the

steel, bringing the paint away from the substrate thus causing the early breakdown of

the system due to lack of adhesion.

5. What is cathodic disbandment and under what circumstances does it occur?

If the impressed current exceeds the corrosion current hydrogen gas bubbles are

evolved form the metal substrate ie the interface between material and coating. This is

significant problem when coating defects are present due to stripping action caused by

the hydrogen bubbles, the coating disbondment is known as cathodic disbondment.

Surface preparation

1) What is the number of the Swedish standard contained within BS 7079 and list the rust

and blasting grades together with their brief tittles?

The Swedish pictorial standard 05-59-00 is contained within BS 7079 Preparation of

steel substrates prior to the application of paint and related products.

The Swedish standard gives visual information on the following.1

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Rust Grades: - which depict the condition of steel before preparation.

A Covered in mill scale with little or no rust.

B A mixture of mill scale and rust.

CMill scales gone, rusted with slight surface pitting.

Dhaving rusted and pitted

Blast Cleaning Grades;

Sa1- Light blast cleaning

Sa2- Thorough Blast cleaning

Sa2 Very Thorough Blast cleaning

Sa3 Blast cleaning to visually clean steel

Grades of wire brushing

St 2- Thorough hand and power tool cleaning (manual)

St3 - Very thorough hand and power tool cleaning (Mech.)

2) List blast clean surface. Give a comparison of blasting grades to SSPC,BS 7079,

BS 4232 and NACE.Sa1 Light Blast cleaning: When viewed without magnification the surface shall be free

from visible oil, grease, dirt and frompoorly adhering mill scale.

Sa2 Thorough blast cleaning: When viewed without magnification the surface shall be

free from visible oil, grease, dirt and from most of mill scale, rust .paint coating and

foreign matter. Any residual contamination shall be firmly adhering.

Sa2 1/2 Very Thorough blast cleaning: When viewed without magnification the

surface shall be free from visible oil, grease, dirt ,mill scale, rust .paint coating and

foreign matter. Any remaining traces of contamination shall show only as light stain inthe form of stripes or spots.

Sa2 Thorough blast cleaning: When viewed without magnification the surface shall be

free from visible oil, grease, dirt, mill scale; rust .paint coating and foreign matter.

It shall have a uniform metallic colour.

SSPC BS7079

SS 05 59 00

BS 4232 NACE

White metal-SP 5 Sa 3 1 st quality Grade 1

Near white metal SP 10 Sa 2 1/2 2 nd quality Grade 2Commercial finish Sa 2 3 rd quality Grade 3

Light blast and brush off Sa 1 N/A Grade 4

3) What factor influence how clean and rough the surface becomes after blast

cleaning?

The cleanliness of the steel surface and its amplitude are governed by the abrasive

characteristics and human features as follows.Abrasive- Size, Shape, Density, Hardness

Human factor-Speed, Angle, Distance, Time

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4) Give the essential requirements for abrasive blasting?

The equipment required including safety features as follows.

Compressor providing air supply 100 psi

a. Pressurised pot containing abrasives

b. Liquid separator is moisture filter

c. Carbon impregnated hoses and external couplings

d. Dead mans handle for direct operator control

e. Blasting nozzle

f. Personnel protective equipments-Air fed helmet, ear defender, boots, gloves,

leather apron.

5) Some metals are hard to prepare and paint? Name three and how you might prepare

them?

New Galvanising: sweep blasting, Hand abrades, etch primer.

Aluminium: Sweep blastHand abrade For thin gauge aluminium an etch primer is used prior to intermediate

and finish coats. Not to be blast cleaned. Chlorinated hydrocarbon shall not be used.

Etch primer-polyvinyl butyl.

Stainless steel

Sweep blast Only aluminium used as blasting medium.

6) What is the rouge peak? What problem can it cause?

Rouge peaks are peaks which stand out above the required profile and should beavoided if applying thin coatings as they may lead to spot or flash rusting.

7) How do you measure surface profile? Explain.

The surface profile may be measured by a number of methods including the use of a

surface profile needle gauge. surface replica tape (testex tape) or a surface comparator.

Surface replica tape: Testex tape or press o film are the commonly used surface replica

tape. It is used to conjunction with a dial micrometer, has the advantage of providing a

permanent record. The procedure for carrying out this test is as follows.

a) Zero the micrometer ensuring the flat contact points are cleanb) Remove paper backing and stick testex tape to the surface to be measured.

c) Rub the testex paste in to the troughs using blunt instrument until peaks can be seen

butting up to the transparent plastic.

d) Remove the testex tape from the surface and measure the overall thickness with

dial micrometer.

e) Deduct 50 microns from the reading obtain the amplitude.The plastic layer to

which the testex paste is attached is 50 micron thick.

8) List all safety equipment and clothing required for open site blasting.

a) Use ofcarbon impregnated hoses to reduce the chance of static shock.

b) Use of dead mans handle for direct operator control.

c) Keep the hoses straight as possible to prevent kinks which may lead to a blow out.3

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d) Water and oil traps.

e) Hyperdermic needle gauge to control the nozzle pressure.

f) Operator should wear the protective clothing including air fed helmet, leather apron,

boots, gloves, ear defender.

g) Warning signs at the area, barrier tape.

h) Keep the compressor pressure below 100 psi.

Paints and Paints application

1) what are the important properties of paint?

a) Ability to preserve the surface from corrosion& other type of deterioration.

b) Show some sacrificing effect.

c) Decorative purpose.

d) Opacity, tinting power, resistance to acid alcoholic and light.

2) Give the three basic ingredients within solvent carrying paint and list the job each

has to do?

A traditional solvent carrying paint consists of three basic ingredients these are.Binder; Binds the particles together and holds them in suspension

Gives the paint its finish

Makes the coating adhere in to the surface

Gives flexibility to the paint film.

Converts the coating to a solid dry film.

Gives resistance to water, chemical, and abrasion.

Pigment :

Gives colour to the paint.

Gives opacity to the paint.Gives resistance to acids, alkalis and light.

Solvent:

Forms the evaporative part of the drying process.

Thins the paint so it can be applied easily.

Washes out the brushes and equipment.

Acts as a degreasing agent if approved.

3) Name five binder/solvent combinations?

Binder solventstrongest Epoxy acetone High power

Chlorinated Rubber Xylene

Alkyd resin White spirit

weakest Emulsion Paint water Low power

4) Name 6 opaque pigments and give their respective colour?

Carbon Black

Compound of calcium Red, yellow

Compound of cobalt BlueCompound of chromium Green yellow, orange

Compound of iron Brown red yellow

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Titanium dioxide White

4A)Rust inhibitive pigments: anti corrosive Zinc chromateYellow Zinc

Red lead & Iron Oxide-Red, Coal tarBlack, Calcium plumbateWhite

4B) metallic pigments Zinc, Aluminium

5) Name the Paints & give their drying and curing methods.

Emulsion coalescence

Alkyd Solvent evaporation followed by

oxidation

Chlorinated rubber Solvent evaporation

Two pack epoxy Solvent evaporation followed by

chemical curing

Fusion bonded epoxy Heat cured

6) State what condition paint must stored?

In a dry lockable well ventilated building away from any source of heat. Material

should be stored at least 5 Deg C Below the flash point and current legislation and

manufacturers instruction should be followed.

7) Name five methods of applying paints and compare the advantages and limitations

of each other.

Brush application; Advantages : Effective for applying primer as it works paint well in

to a substrate, which gives optimum coverage and mixes in any dust particles ,thus

achieving optimum adhesion. Do not produce overspray

Less environment hazardLess wastage and less spotting.

Limitations: Slow production

May not have uniform thickness

High quality brushes quite expensive.

Roller application:

Advantages; Quicker than brush for large flat surfaces.

With extension poles easy to access at elevated locations.

Limitations: Non uniform paint thickness.

Paint does not work in to a surface.Some specifications not permitting roller applications.

C) Conventional Spray:

Advantages

Good finish

Suitable for applying thin material

Less operating pressure more safe

Less over spray, quicker than Brush

Limitations:

Less production.Gravity fed guns to be operated at upright position only.

High viscous paint application not possible.

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Airless spray:

Advantages:

Higher production

Highly viscous paints easily applied.

More portable. Uniform coating can be achieved .High DFT

Limitations

More wastage and overspray

Higher equipment and maintenance cost

High risk of safety due to high pressure operations.

e) Electrostatic spray

Advantages

More uniform thickness can be achieved,

Good finish

Less overspray

Limitations

High equipment cost.

8) Give 6 types of anticorrosive primer.Zinc chromate

Zinc phosphate

Red lead

Calcium plumbate

Red oxide

Coal tar

9) State the advantages of airless spray over conventional spray.

High rate of production

Uniform film thickness can be achieved.Less fog and rebound

Size and angle of the tip can be controlled by the quantity of flow and pattern.

High viscous paint can be easily applied.

10) What paints have to be considered when brush paintings?

Primers have to be considered when brush painting because brushing works a paint

into a substrate-surface which gives optimum coverage and mixes in any dust particles

thus achieving optimum adhesion.

11) What method of paint application is performed for primer and why?

Primers have to be considered when brush painting because brushing works a paintinto a substrate-surface which gives optimum coverage and mixes in any dust particles

thus achieving optimum adhesion.

12) Define the tie coat and give an example.

A coat of paint which can tie two normally incompatible systems together.

(Where adhesion problem solvent stripping or bleeding might occur.)

Eg. Aluminium leafing primer for the application of Alkyd over Bitumen due to

bleeding.

13) Describe barrier paint system and sacrificial paint coatings:-

Barrier paint system :- The substrate is isolated from the environ mental which causes

corrosion by using a coating of low permeability. This may be achieved by applying a

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E.g. epoxy, polyurethane.

Sacrificial coatings:

Sacrificial coatings contain pigments which cathodically protect the iron or steel

substrate to which the paint is adhered. These pigment particles eventually corrode

thereby sacrificing themselves to corrosion. In order to have these properties the

sacrificial pigment must be ignoble to the material to be coated. Zinc and aluminium

are the most common types of pigments employed.

17) Describe what qualities a laminar pigments gives and name four pigments.

Laminar pigments are small flakes which have leafing effect when a paint drives, this

means the flakes of pigment overlap each other like tree leaves on the ground. The

result in an excellent coating to resist the passage of water. With improved tensile

strength. M.I.O., mica, glass flakes and aluminium flakes are examples of laminar

pigments.

18) Define the term pot life, Induction period, Shelf life.

Pot life:- The pot life is the maximum period of time after mixing in which the paintmust be used. This can vary few minutes and depends on Temperature..

Induction period: - Induction period is the minimum period of time during which

mixed compounds are left to stand before use. This is allowing for certain chemical

reaction to take place and or the time allowed for air bubbles to escape. Induction

periods are typically up to 30 minutes.

Shelf life:- The maximum period of time a paint in good condition in its container

before opening and recommended by the paint manufacturer.

Paint and Film testing

1) What does a fineness of grind gauge measure?

The fineness of grind gauge measure the degree of dispersion of a paint. Also known

as hegmen grind gauge.

2) What does a crypto meter measures and two examples of crypto meter.

A crypto meter measures the opacity or the hiding power of the paint posses.

P Fund crypto meter,

Hiding power charts.

3) What determines the degree of gloss of paint may posses?

The degree of gloss determined by

a) degree of pigment dispersion.

b) Size of pigment particles

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c) The pigment volume concentration

d) Binder type.

4) What is a flash point? Describe the procedure for determination of flash point.

Flash point is the minimum temperature at which the vapour of liquid will ignite if an

external source of ignition was introduced.

Flash point determination of paints or solvents may be carried out in accordance with

BS 3900 part A9 using a closed cup of Abel type.

Procedure:-

Fix the Abel cup containing the substance for the assessment into a water bath.

Activate the source of ignition every deg C rise in temperature.

Apply a heat source to the water bath and monitor the air/vapour temperature in the

Abel cup.

A flash point temperature is identified when a blue flame flashes over the substance

being assessed.

5) What is density and how do you asses it? Give to reasons for its use.

Density is weight per unit volume of substance posses.

Density = mass/volume gm / cc

Procedure for measuring density using a 100 cc density cup.

Weigh the cup to the nearest deci gram using a laboratory balance with a 1000 gm

capacity and a sensitivity of +/-- 0.1 gm

Remove the cover and fill with paint to within 2.5 mm of brim

Carefully replace the cover so that air any excess paint is expelled through the vent

Wipe off any surplus paint from the cover then re weight.

Determine the weight of the paint by subtract on.

Divide the weight by 100 if the density in g/cc is required.

Uses:- a) this procedure can be used to determine the quantity of any added thinner.

b)to determine whether a two pack paints have been mixed in the correct .

preparations.

6) What is viscosity and what equipment is used to measure viscosity of a free flowing

paint and thixotropic paint?

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Viscosity is a measure of a fluids resistance to flow.

SI unit N.s/sq. m C.G.S unit= poise Measure by using Viscometers

Viscosity of free flowing paints can be measured using a flow cup, there are many

types including Ford cup, redwood and Zohn flow cup.

Procedure for measuring viscosity using a ford cups no 4.

a) Bring temperature of the paint within 20+/- 0.5 deg C

b) Level the apparatus ,then with the end of one finger over the orifice of the cup,

rapidly fill it with paint.

c) Allow a moment for air bubbles to rise then draw a flat edge across the top of the

paint level with the edges.

d) Remove the finger from the orifice and start the stop watch simultaneously with thecommencement of the paint stream. The watch is stopped when the first distinctive

break in the paint stream occurs.

e) The time in seconds taken as the viscosity.

For the thixotropic paints the viscosity can be measured by a rotation viscometer or

another type of viscometer paints. (Kerb stormer viscometer cone and plate

viscometer and roto thinner)

7) What is specific gravity and how is testing for s.g. carried out?

Relative density or specific gravity is the density of any substance compared to the

density of water.

Specific gravity = Density of the substance/density of water.

8) Name the three adhesion tests and describe how one of them is carried out?

Adhesion is the force that resists the separation of two surfaces in contacts.

a) Cross cut test b) Cross hatch c) Dolly test.( pull off adhesion test)

Procedure for pull of adhesive test

a) Clean and degrease the surface to be tested.

b) Roughen the surface fine/medium grain emery sheet.

c) Mix regular araldite and stick dolly dolly to the surface and leave for 24 hours at 25

deg C

d) Cut paint around the dolly down to the substrate using a special cutter.

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e) Attach pull off instrument and apply pulling the force.

f) Test results require careful interpretations. Some normal values obtained for

acceptable Adhesion are as follows. 1500 psi - epoxy based systems

3000 psi - alkyd based systems 12000 psi - zinc etch primer.

9) Name four artificial weathering device and what are these designed to stimulate?

Artificial weathering devices are designed to create accelerated weathering to speed up

the duration of different test to speed up the duration test to be carried out to determine

the coating systems behaviour at specific condition.

a) tropical box:- to simulate high humidity environment.

b) Salt spray test:- Stimulate a marine environment.

c) Water soak test:- to access paint systems resistance to water absorption.

d) Cold check test:- test for low temperature contraction cracking.

e) Temperatures cycling :- to access film flexibility at alternate hot and cold

temperatures.

10) State two drying and curing tests and how they are operated?

Ballotini test: - Tiny glass balls known as ballotini are allowed to fall in to a freshly

painted test panel. The test panel moves slowly beneath the falling balotini over pre set

period of time. the time of the test is variable and the speed can be adjusted so that the

panel 300 mm long can take between 1 to 24 hours to test, where the balotini fails tostick to the painted panel drying has occurred.

Styllus test :-

The stylus test employs a series of trailing needles which pass over the wet painted

panel ,because the needles are set at different tensions at can be established when the

paint is tack dry hard dry and fully cured.

11) What is w.f.t? How does you measure it? What are the advantages of using it?

Wet film thickness is the thickness measured immediately after a coating has been

applied. The wet film thickness may be found by using a comb gauge or an eccentric

wheel.

Procedure for measuring w.f.t using a comb gauge.

a) immediately after the application of paint the comb gauge should be firmly place

don the surface in such a way the teeth are normal the plane of the surface.

b) The gauge should then remove and the teeth examined in order to determine theshortest one to touch the wet film. The film thickness should be recorded as as

lying between the last touching tooth and first non touching tooth.

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c) At least two further readings should be taken in different places in a similar manner

in order to obtain representative results over the painted one.

Advantages:-

- if the w.f.t. is known any deviation from specified thickness range can be

immediately rectified.

- If the w.f.t is known the approximate DFT can be calculated if the volume

of solids are known DFT= WFT . VS/ 100

12) What is DFT? State the principle of being able to use a banana gauge for

measuring DFT? State calibration procedure for banana gauge?

The banana gauge only used for measuring the thickness of non ferromagnetic coating

applied over a ferromagnetic substrate.

Calibration procedures :-

a) Choose a magnetically insulated shim of known thickness, close to the thickness of

the paint you expect to find.

b) Place the shim on the same substrate surface finish as the surface finish on which

the paint to be measured ids attached. e.g. if the paint is on a blasted surface

,calibrate the gauge on a uncoated blasted surface.

c) Place the magnet on the shim and press firmly on the instrument, wind the scale

wheel forward (away from you) until the magnet is definitely attached to the

shim/substrate.

d) Gradually wind the wheel backwards slowly until the magnet detaches itself. At

this point move the cursor on the instrument to the thickness of the shims shown on

the scale wheel. With some instrument the scale itself must be moved to line up

with the fixed cursor. The instrument is now calibrated and may be used to measure

the d.f.t of any non magnetic film to within a claimed accuracy of +/-- 5% in some

cases.

13) Describe a destructive test for determining the D.F.T of the paint?

Paint Inspectors gauge:-

Paint Inspectors gauge in one such type of destructive test gauge. A small V shaped

Cut in to the coating at a fixed angle governed by a cutter built in the gauge. The

width of the channel is then measured on a graticule scale by means off microscope

which is built in with the instrument.

14) How do you calculate DFT, WFT, VS%?

DFT = VS % . WFT / 100

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WFT = DFT .100 / VS %

VS% = DFT .100 / VS %

15) Describe the cathodic disbondment test :-

If the impressed current exceeds the corrosion current hydrogen gas bubbles are

evolved from the metal substrate i.e. at the interface between the material and coating.

This is significant problem when curing defects are present due to as tripping action

caused by the hydrogen bubbles, the coating disbondment known as cathodic

disbondment.

The test incorporates a coated test panel with hole drilled in to the coating. This

simulates a paint film defect. Surrounding the hole a plastic tube is glued down and

filled with sodium chloride solution to act as an electrolyte. Wires from battery are

attached to the panel and to a metal rod set in to the liquid of plastic tube. a current is

then impressed to make the panel cathodic. The coating is assessed after a period oftiming e.g. a few weeks for the amount for stripping which has occurred from the

boundary of the hole.

Weather condition

1) Name three environmental conditions when would you stop painting? 2) When shall

coating not be applied?

Environmental conditions rain, snow, high wind

It is not permissible to apply paint when the following conditions apply:-

- during snow rain or high wind

- When the air or metal temperatures is down to within 3 deg c of the dew

point temperature.

- When the air and metal temperatures are below 5 deg C

- When the relative humidity is above 90 %

3) Why the environmental test is carried out during a painting project?

Environmental tests are carried out during a project in order to verify the weather

conditions are acceptable to the specifications to carried out the painting inspection.

4)State the condition at which BGas allow painting to take place? Or what are the acceptable

application condition for blasting and painting?

Under BGas specification the acceptable application condition for blasting andpainting are-

when there is no rain, snow or heavy wind the air and metal temperature is at least 3 deg C

above the dew point temperature. Relative humidity less than 90 %.

The Temperature for application are within the manufactures given limit

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4) Explain RH, DP, Ambient temperature and Steel temperature ;-

R.H. :- Relative humidity is the amount of water vapour in the air expressed in a

percentage.

Dew point: - Dew point is the temperature at which condensation would form on a surface.

Ambient temperature :- It is the surrounding air temperature also referred as dry bulb

temperature.

Steel temperature:- it is the temperature of the substrate prior to painting.

(Magnetic steel thermometer, digital thermometer)

5) Explain how environmental test are carried out? What equipment is used to find RH

and DP? Explain its use.

Environmental conditions like RH and dew point are measured using a hygrometer of

which there are many types. The whirling hygrometer or psychrometer consists of two

mercury thermometers set side by side in a frame in a frame in which is provided with a

handle and spindle so that the frame and thermometer can be rotated quickly about

horizontal axis. The bulb of one thermometer is called wet bulb thermometer, is covered

with a closely fitted cylindrical cotton wick. The end of which dips into the distilled water

or clean rain water contained small cylinder attached to the end of the frame.

The frame is rotated by hand for 30 to 40 seconds as fast as possible so that the bulbs pass

through air at least 4 miles per sec. This causes the water to evaporate from the wet bulb.

the wet bulb cools down to a constant wet bulb temperature due to the evaporation rate of

water from the wet wick. Always read the wet bulb temperature before dry bulbtemperature immediately after rotation. Repeat the operation until consecutive readings of

each bulb temperature agree to within 0.2 deg C.

If it is 100 % RH the wet bulb will be the same temperature as dry bulb, because no

evaporation can occur. i.e. the air is saturated .If the wet bulb and dry bulb temperatures

are the same the current temperature is the dew point.

The RH and dew point can not be read directly from the apparatus, hygrometric tables or

special slide rules must be used.

Inspection standards and Specifications

1) What does BS 2015 glossary of paint terms refer to and give three examples.

Faults which occur with paints are described in BS 2015 glossary of paint terms.

These faults are due to three main causes.

1) Fault in the can (Manufacturing faults)

2) Problem which occur due to poor preparations

3) Problem which occur due to incorrect or poor application or interference by weather.

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Bleeding: The action of a material in penetrating and discolouring a coating a coating

applied on top of it.

Blistering: The formation of dome shaped blisters in a paint film. They can be blisters

which are usually caused by the expansion and contraction of the paint film against the

substrate or osmotic blisters which can be caused by water / solvent entrapment or

hygroscopic salts left on a blast cleaned surface.

Chalking: The breaking down of a paint film become chalking or powdery usually due to

disintegration of the binder caused by attack from U. V. light or severe weather condition.

2) What does BS4800 and how it is used in construction industry.

BS 4800 Paint colours for building purpose specifies 100 colours which have been

selected from the frame works of the 237 colours contained in BS 5252.

Each colour in BS 4800 is identified by three chief qualities as follows.

Hue:- The first part signifies hue or colour and consists of an even number of two

numerals and 12 main hues are used and numbered.

02- red purple

o4 reds

06 yellow red

08 yellow red

10 yellows

12 yellow green

14 green

16 green blue

18 blue

20 Purple blue

22 Violets

24 Purples

Greyness: The second part signifies greyness i.e. the apparent amount of difference in

greyness between one colour with another. Five grades are used each detained by a letter.

A Maximum greyness

B - 15 to 29

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C- 31 to 40

D Minimum greyness

E Pure No greyness.

Weight: Saturation

Colour of similar hue and greyness may differ in colour brightness or intensity of colour.

This quality termed as saturation, may be defined as the intensity of any particular hue

when compared with a neutral grey of similar lightness of the spectrum colours being the

most intense or of highest saturation.

The weight is given in pairs of numbers from 01-56. Groups of colours within each of the

five greyness ranges are graduated high to low value.

Each of these graduations is numbered,

A Greyness 01 - 13

B greyness 15 - 29

C greyness 31 - 40

D greyness 43 - 45

E greyness 49 56

BS 4800 can be used

Can be used to identify existing colours when maintenance painting and is a method by

which all manufacturers can make exactly the same colour.

3) How do Bgas define the following?

a) New galvanising; - A galvanised steel surface up on which cohesive oxide layer has not

yet formed. (Bright, shiny less than three months before)

b) Weather Galvanising: - A galvanised steel surface up on which a cohesive oxide layer

has formed by natural weathering.(dull and lack of sheen)

c) Long term protection: - the estimated period for the corrosion protection is typically 10

years.

D) Medium term protection; - Typically 5 years.

E) Short term protection: - Typically 2 to 3 years.

4) What is the procedure for removing oil, grease from a substrate after preparation has

taken place?

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If oil or grease found on a surface after it has been prepared that area must be swabbed

with an approved solvent followed by a 2 % detergent wash washing with clean water

through drying and re blasting.

5) What is procedure for removing oil, grease from a surface before preparation

commences?

Small areas of oil and grease shall be removed with an approved solvent where as large

areas can be given to low pressure detergent washing which must be followed by rinsingwith clean water and thorough drying.

6) What is the procedure for remove algae and mould growth from pipe works?

Algae and mould growth shall be treated with a biological agent and left for 24 hours at

least in order that biocide can kill the spores. It shall than be removed by scrubbing with

stiff bristle brushes and clean water wash.

6) What distance must be left at areas to be welded whan painting?

For zink rich paint 75 mm shall be left from the end preparation.

7) How much new paint overlap required over old repairs?

Minimum 100 mm.

8) what must one pneumatically and electrically operated power tool equipment be ?

All equipments whether pneumatically or electrically operated shall be earthed. All

equipments shall be non spark and flame proof.

9) What type of sheeting may or may not be used for protection against spillage and

spotting?

Sheeting of non flammable nature must be employed to protect areas against spillage and

spitting. Tarpaulins must not be used.

10) What areas of work does PA 10 not cover?

PA 10 not covers painting work of the following.

a) Below ground (buried)

b) Offshore installation

c) Internal coating of piers

d) Stove enamel coating.

11) What is BS 7079 ?

Preparation of steel substrates before application of paints and related products.

12) What is BS 3900 And BS 4800?

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BS 3900 Method f tests for paints.

BS 4800 Specification for paint colours for building purposes.

14) What is BS 5493?

Code of practice for protective coating of iron and steel structure

13) What is BS 5750?

14) As inspector what do you consider as your main responsibilities?

a) To asses the condition of substrate prior to treatment

b) To inspect surface preparation in accordance with BS 7099: measure and record

amplitude once in daily.

c) To ensure material used on site are to clients specification.

d) Relative humidity, dew point, air temperature, metal temperature to be checked andrecorded at least four times daily.

e) Wet and dry film thickness to be checked and recorded frequent intervals.

f) To witness and and inspect application of each coat and inspect completed paint system

in accordance with the clients specification and good paint inspection practice.

g) To submit daily and weekly reports recoding all the relevant information as required by

the client. Copies to be retained by inspector.

15) List contractor malpractices.

a) Using unqualified personnel.

b) Using unsafe plant and scaffolding.

c) Using equipment in poor condition,

d) Carrying out further work before inspection has taken place.

e) Attempting to skip a coat.

f) Apply the coating system in wrong sequence.

g) Painting or preparing a surface during bad weather condition: rain, snow mist wind etc.

h) Using incorrect paint.

i) Using a paint which out of expiry date

j) Applying too much solvent to the paint.

k) In correct storage of paint.

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l) Applying low thickness coating.

m) Attempting re use expendable abrasives.

n) Insufficient blasting or painting a difficult access area.

o) Cleaning surfaces with cottons. or rags.

p) Not observing induction and pot life timings.

q) Use of incorrect paint type or mixing different manufacturers product.

r) Insufficient attention paid for house keeping.

Paint Faults

Alligatering: - A drastic type of crazing producing a pattern resembling the the hide of a

crocodile or alligator.

Bleeding;- the action of a material in penetrating and discolouring a coating applied on topof it.

Bittiness; - The process of particles of jell, flocculated material or foreign matter in a

coating material or projecting from the surface of a film.

Blooming: - A deposit resembles the bloom on a grape that some times forms on the gloss

film of a coating causing loss of gloss and dulling of colour.

Blistering;- Formation of dome shaped blisters or projection in paints in the dry film of a

coating material by local loss of adhesion and lifting of the film from the underlyingsurface.

Blushing;- Milky shady appearance inWhite.

Chalking: - The breaking down of a paint film to become chalky or powdery usually due

to the disintegration of the binder medium caused by attack from U.V. light or severe

weather condition.

Checking: - cracking that comprises fine cracks which do not penetrate the top coat and

are distributed over the surface giving the semblance of a small pattern.

Cissing;- a failure of the paint to form a continuous film usually due to oil, grease being

present on the surface.

Cobwebbing;-The formation of a fine filament of partly dried Paint during the

sprayapplication of a fast drying Paint.

Cratering;- The formation of small bowl shaped depression in the film of a coating

material.

Crazing;- Cracking that resembles checking but the cracks are deeper and broader.

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Cracking:- Generally the splitting of a dry paint or varnish film usually as a result of

ageing.

Dry spray: - The production of a rough or slightly bitty film form sprayed coating material

where the particles are insuffiently fluid flow together to form a uniform coating.

Flaking: - lifting of the coating material from the substrate in the form of flakes or scales.

Flocculation:- The separating out of a paint constituents in the tin and their refusal to bestirred back together again.

Grinning:- Showing through of the substrate dud to the in adequate hiding power of the

coating material.

Holidays:- Missed or poorly coated areas on a painted surface.

Lifting :- softening ,swelling or separation from the substance of a dry coat as the result of

the application of a subsequent coat.

Orange peel ;- The uniform pock marked appearance in particular of a sprayed film

resembles the peel of an orange due to the failure of the film to flow out to surface.

Osmotic blisters: - formation of dome shaped blisters which can be caused by water

entrapment, solvent entrapment or hygroscopic salts left on a blast cleaned surface.

Pin holing: - The formation of minute holes down through a paint coating caused by

escaping air bubbles.

Ropiness :- ( Brush marks) Pronounced brush marks that have not flowed out because of

poor properties of the coating material.

Residual tack: - The degree of stickness remains in a film of a coating material which does

not reach the true tack free stage.

Saponification:- The formation of a soap by the reaction between a fatty acid ester and an

alkali.

Wrinkling:-The development of wrinkles in a film of a coating material during drying

mainly due to the initial formation of a surface skin.

BGAS PA 10

1) What is Bgas PA 9?

Refers to paint properties and performance requirements.

2) What is BGAS PA 10?

Refers to the technical specification for new and maintenance painting at works and site

for above ground pipe line and plant installations.

3) What are the definitions for the following from PA 10?

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A) Compliant coating: - A coating which complies with the Environmental protection act .

b) Long term protection Typically 10 years

Medium term protection typically 5 years

Short time protection typically 2-3 years

d) Fully weathered Galvanising:- A galvanised steel surface upon which a cohesive

oxide layer has formed by natural weathering.

e) Dew point: - the temperature at which condensation would form on asubstrate.

f) Relative humidity:- the amount of water vapour in the air expressed as a

percentage.

g) Induction period : The length of time a paint is required to stand after mixing and

before application. This time allows air bubbles to escape and or chemical reaction

to take place and is specified by the paint manufacturer.

h) Pot life;- The length of time ( following induction) that a point remains in an apply

able condition according to the manufacturers instruction.

i) Shelf life:-Length of time a paint can be stored,before it can be used.

j) T wash;- An etch primer for zinc metal surfaces Blue in colour it turns black upon

drying if it has been applied successfully.

k) Sheeting for protection:- Sheeting of a non flammable nature must be employed to

protect areas not being prepared or painted from contamination.

l) Masking outs:- the contractor must mask out items to be protected during

preparation and painting in order to prevent malfunction of the plant. Such areas

typically or fire protection equipment, weld end preparation, atmosphere sensing

head ,vent on control equipment, flame trap, lubricating points name plate etc.The

contractor is responsible for removing all masking material.

4) What are the Condition for final surface preparation:-

When conditions in the working area are such that metal surfaces are moist, damp orwet, final preparation shall not be carried out.

- Any surface preparation procedure or method of cleaning shall not be

allowed to contaminate wet paint film.

- Equipment used shall be of non sparking type.

- Electrically operated tools are not permitted.

- Power tools operated by compressed air shall have oil trap vapour trap fittedto the compressed air lines.

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- All contaminants shall be removed by means of an approved solvent.

- Allage and mould growth when in evidence shall be treated with biocide

agent and left for at least 24 hours in order that the biocide can kill the

spores. It shall then removed by scrubbing with stiff bristles brushes and

clean water or by use of high pressure water wash.

- All surfaces shall normally be dry before painting commences.

5) Condition for application of paint as per PA 10 :-

Paint shall normally applied when

a) the RH % is less than 90%

b) the air and metal temperature is at least 3 deg C above the DP

c) Ambient and substrate temperature should not be below the set out by the paint

manufacturer for particular paint.

d) Paint shall not normally apply when conditions in the working zone are such that

the working surface becomes moist or dump during the painting operations.

e) Painting equipments shall be used in accordance with the paint manufacturers

recommendations.

f) All paint shall be applied in order to produce a firmly adhering continuous film,

free from misses, runs tears, sag etc.

g) Stripe coating shall be carried out to welds edges etc in order to achieve a full paintfilm thickness as specified.

h) All painted areas must be thoroughly dry before being over coated and any

contamination of the paint film should be removed before further coats are applied.

i) Final coating shall be free from significant visible imperfection.

Health and safety

1) What document state health and safety at work?

H.A.S.W.A. : - hazardous and safety at work act1974.

2) What year was the health and safety act passed?

The control of substances hazardous to health regulations 1988 come in to force 1 st

October 1989(COSHH regulations).

4) How long would be records of examinations monitoring test for five years and 30

years for identifiable employees.

5) EPA environmental protection act waste material disposal.

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6) What is VOC?

Volatile organic compound.

7) How would structures coated by lead based paints be blast cleaned?

Wet blast system or enclosed recovery blast system shall be used for removing lead

based paints.

8) Name some heavy metals used in coating and painting?

Work permit is an clearance to carryout an work in a safer manner .as per contract

specification.

Name and describe three tests for locating soluble iron salts and mill scale on a blasted

Substrate.

Soluble iron salts: The potassium ferricyanide test may be used to detect the presence

of colourless soluble iron salts which may be present in the pits after blast cleaning. Ifthee salts present they will accelerate corrosion causing rust spot which may in turn

break the bond of any applied coatings leading to failure of the coating system. Spray

the fine mist of distilled water on to a small area of the surplus using a scent spray type

of bottle.

Wait a moment for any water droplets to evaporate and then apply a potassium

ferricyanide test paper by pressing down for 2 to 5 seconds.

Remove the test paper and check to see if any salts have been drawn by capillary

action. they show as Persian blue spots.

Soluble chlorides; The silver nitrate test may be used to detect the presence of soluble

chlorides.

Preparations; make 2% solution (by weight) of silver nitrate in distilled water.

- Cut strips of filter paper and store in a sealed plastic bag.

Procedures;

a) wet filter paper strip with silver nitrate solution.

b) Press the test paper on to the steel surface and leave in contact for 20 seconds.

c) Remove the filter paper and wash thoroughly in distilled water .

d) Any silver chloride formed remains on the paper when the paper is immersed in to

photographic developer, the chlorides shows up as brown black areas.

Mill scale: To test the presence of mill scale particles left behind after blasting to

BS 7079 grades Sa 3; the copper sulphate test is used.

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Procedure: A fine mist of slightly acidic copper sulphate solution is sprayed on to a

localised area of approximately 100 mm in diameter. The steel turns a bright copper

colour and any mill scale particles show as black spots.

Name five items that can be included in paints to improve its performance or

suitability for a certain use.

a) Drier or catalyst; Driers added to accelerate the drying process. Drier consists of

compound of metal e.g. Napthenats of cobalt, zirconium Manganese.

b) Plasticizers: a plasticizer is a paint reduces the brittleness of the dried film by

allowing the molecules of the paint to move more easily. There by making it more

plastic.

c) Stabilisers; Holds modern synthetic film formers intact and helps to prevent

flocculation occurring in tin.

d) Extenders: Extenders are cheap mineral powders which can be added to paint in

order to make it flow easily, increase opacity and reduces cost.

e) Anti skinning agent: anti skinning agents prevent or slow down the formation of a

skin on the surface of a paint in its container by retarding or eliminating polymer

growth due to oxidation.

f) Thixotropic agent; thixotropic added to paint give a gelly like structure which give

the paint high build and anti sag properties.

Identify six paints by their binder name.

Alkyd, Cellulose, Chlorinated rubber, emulsion, epoxy, poly urethane, vinyl

What is the difference between thermosetting and thermoplastic?

Paints which melt when heat is applied are known as thermoplastic coatings.

Coatings which do not melt after the application of heat are known as thermo set

coatings.What is impressed current and what problem can arise from its incorrect use?

Impressed current is a type of cathodic protection system.e.g. used for large areas ofpipes.

If the impressed current exceeds the corrosion current hydrogen bubbles are evolved

from the metal substrate i.e. at the interface between the material and the coating.

This is a significant problem when curing defects are present due to stripping action

caused by the hydrogen bubbles leads to coating disbondment is known as cathodic

disbondment.

Name the two types of paint mill and give two examples of each?

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1) Direct charge mill: which take and mix all the raw ingredients together .e.g.

Ball mill, Attritor mill, High speed dispersers

2) Pre mix mills; Take the ingredients which have been pre mixed to a rough

consistency and refine this mixture to high quality paint. E.g. Bead mill (pear or sand

mill), Colloid mill, Tipple roll mill, single roll mill.

What is the title of BS 3900?

The British standard for dealing with testing is BS 3900 method of test for paints.This document is divided into eight separate parts each one dealing with a separate

aspects of testing procedures. They are

Group A test on Liquid paint (excluding chemical test)

Group B test involving chemical examinations of liquid paints and dried paint films.

Group C Tests associated with paint film formulation.

Group D optical tests on paints

Group E Mechanical tests on paints

Group F Durability tests on paint films

Group G Environmental tests on paint films.

Group H - Defects

Non destructive D.F.T. gauge -- Electronic gauge, Banana gauge

Destructive D.F.T Gauge Paint Inspectors gauge.

what two coats of paints are applied at works?

At works the following two coats of paints are applied

a) High solids solvent based Epoxy primer 75 Microns minimum.

B) Epoxy M.I.O 75 Microns minimum.

what is the maximum allowed time for priming to take place following preparation and

by what method is primer applied?

The maximum allowed time for priming to take place after preparation in all cases is 4

hrs. The brush is very effective for applying primer as it works paint well into asubstrate and produces an excellent finish.

What do BGas class as a hot duty service?

Metal surfaces that will reach a temperature in excess of 99 Deg C when in service is

classed as hot duty service.

Fire or Flame shall not be used to cleanout paint kettles

Name a black pigment in common use apart from coal tar.

Carbon black.

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Reversible head Used to clean out any blockages in the orifice of the nozzle.

Fluid Tip Lined with tungsten carbide .the orifice size governs throughput of the

paint and the orifice angle governs the size of spray pattern.

1) PA-9: Paint type approved for particular job

Approved paint manufacturer (service and price)

Test to be done by manufacturer.

3) IGE / SR /21 Blast cleaning operation.

Long term protection: Paint system to last without recoat.

White rust Weathered galvanising more than 3 months old.

Manufacturers temperature limit for application.

-Whirling hygrometer and dew point calculator.

Check on hygrometer;

- more freely

- calibration sticker

- Water in column.

- Wick is clean

- Breakage on thermometer.

- Check close to work area

- Take 2 set of reading at least

- Take morning before work commence

- Facing the wind direction.

If profile is more than required amplitude ;

For small area Abrade with emery

Large area; a) Reblast using smaller size abrasives.

b) reduce the nozzle pressure

c) keep distance between surface and nozzle.

d) Time Blast more quickly (less time)

e) Use straight bore nozzle.

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SPA 1

-Complaint solvent based system;

In the finish coat usually used to prevent chalking if epoxy is used.

Urethane.

SPA 6

New galvanising full system minimum 120 microns and must include an MIO coat.

For SS full system minimum 120 microns(Do not require MIO)

-Polyurethane advantages; Polyurethane finish coats are often used to replace epoxy

finish coats. They have the following qualities.

- High gloss

- Retain the gloss

- Hold the colour

- Abrasion resistant

- Easily cleaned

- Good resistance to U.V.light.

Advantages of epoxy

- More flexible

- Used on damp surfaces

- Build thickness

- Chemically cured and hard

- Mechanical resistance.

- Epoxy not cured by oxidising. Cured by chemical reaction between two

components.

Splash zone: oxygen on water is 1/5 % of air and corrosion protection by sacrificial

anode only.(No painting is done)

Temperature of water, saltiness of water.

-Surface preparation depends ;

Type of paint

Length of protection

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Quality of finish

Pressure washing 100 psi maximum

Sweep blasting; To remove any foreign material.

Pressure drop between compressor and nozzle;

Compressor leaky

Too long hose

Leakage in coupling, Kink in hose

-BS 729 Hot dip galvanising.

-Six opaque pigments with respective colours.

Calcium plumbate white

Coal tar- black

Red iron oxide red

Red lead red

Zink chromate yellow

Zink phosphate - white.

Bleeding:

To prevent bleeding a tie coat should be applied.

Alkyd and Bitumen: tie coat should be Aluminium leafing primer.

-solvent stripping; depend on solvent power of paint applied over.

Chlorinated rubber and alkydaluminium leafing primer.

Dry blister Due to localised adhesion.

When applying MIO care should be taken to avoid adding more solvent. i.e. wft may

be wrong.

T wash- To provide a key for new galvanised surface.

Painting application Brush or spray appropriate 4 hour.(except SP4 immediately)

H.A.S.W.A.; - Health and safety at work act 1974

This act deals with the duties of the employer and the employee in the work place.

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The main duty of the employer is to provide a safe working environment. The main

duties of the employee are to keep themselves and others safe at all times by their

action at work. They also have a legal duty to report accidents, incidents or spillages.

C.O.S.H.H.:- Control of substances hazardous to health 1988.

This acts deals with the use, handling, transport storage packaging and labelling of

many hazardous materials. In our industries it deals mostly with solvents sand and

dust.

What additional information you should need when maintenance painting a pipeline

without removing the existing coating/

The following additional information to be recorded is.

- Nature of the existing system must be established to decide the type of

preparation to be commenced.

- Amount of surface contamination.

- Extent of corrosion.

- Extent of paint breaks down.

- Compatibility of the existing system with the new system. if not compatible

select the appropriate tie coat.

- In service environmental condition.

Holiday and pinhole detector

Holiday; misses d or poorly coated areas

Pinhole: Minute defects caused by escaping air bubbles when the paint dries.

5 volts per micron- Procedure;earth the substrate

a) Pass a metal brush(holidays) or wet sponge(pin hole) over the painted surface at

a pre set voltage 9typically 5 volts/micron and at a controlled speed.

b) When a defect is found an audio or visual warning will be given.

c) These areas must be marked repaired and retested.

BS 3900 ; Applied voltage should be less than the di electric strength of the coating

material.

-Mordent solution, t wash, wash primer = etch primer

Aluminium etch primer poly vinyl butylHow corrosion occur?

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a) Naturally occurring b)Electro chemical process c) Through electrolyte.

Bleeding: Discoloration of newly applied coating over existing coating

Blooming; A loss of gloss and milky type appearance due to a wet paint film

coming into contact with cold or damp air.

Lifting; Applying a coat of paint before the previous coating was fully dried causing

patches of the underneath coating to be lifted off in to the newly applied coating.

Solvent stripping: applying a coat of paint with a very strong solvent causing

patches of the underneath coating to be stripped off.

Oxidation; It is a chemical reaction between the binder and oxygen to bring about

the drying of a one pack paint.

Chemical curing: It is a chemical reaction between an epoxy binder and a catalyst to

bring about the curing of two pack paint.

Overspray; Lost of paint on to other surfaces or in to the atmosphere when spraying.

BS 4800 ; it is a range of 100 standardised colours taken from the frame work of

237 colours of BS 5252.

Uses; The ways in all manufacture make paint in same colour.

Galvanic series; List of metal compounds in their order of nobility in sea water at

ambient temperatures.

Gold Noble ( stable )

Silver

Copper

Mill scale

Iron

Aluminium

Zinc ignoble ( un stable)

We can use galvanic series to bring about cathodic protection of steel in two ways.

Bi metallic corrosion, sacrificial coating.

Flash point indication of fire risk

chlorinated rubber 13 to 21 thou =2400 psi

H.B.epoxy 17 to 23 thou= 3000 psi

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Zinc rich primer 17 to 23 thou = 2800 psi

19 thou = 2500 psi.

Manufacturers data sheet;

Product description

Recommended use

Technical information

Application data

Condition during application

Drying and curing time

Recommended painting system

Storage and packing

Health and safety

1) How is Sweep Blast performed?

After abrasive blasting, cut off the flow of abrasive. Only pure air will flow through

the nozzle at the same speed.

Project it on the blasted surface so that any abrasive i.e. grit particles. Dust etc will be

blown off by the air from the blasted Surface. Ensure that no dust particles are present.

I Simple test- stick clear cello tape on the blasted surface& pull it out and check for

any dust particle is present.4. Use of Wet Comb Gauge.

WFT COMB GAUGE. It is pushed firmly into the wet paint so that the outer most

teeth make contact with the substrate.

Held at right angles to the surface. Gauge is removed and the teeth are examined.

WFT lies between the last tooth i.e.

Coated and the first tooth that is Uncoated. Midpoint between this is WFT.

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Theory Question

1. Etch Primers & their uses?

2. Function &use of Solvents ?3.Different Types of Surface Preparation ?

4. Critical. Pigment. Volume .Concentration (C.P.V.C)

5. Preparation Of Two Pack Paints for Use

6.Sealers for High Temperatures Surfaces ?.

7. Purposes of B.S.4800 ?

8. Qualities of Polyurethane Finish Coats ?

9. Advantages & Disadvantages of Epoxy Paint System ?

10.Detail operation of Airless & Conventional Spray System?

11. Action taken when coatings are applied out of Sequence ?12.Risk Assessment when cleaning &Painting ?

13. Problems when Density and Viscosity of a paint are not correct ?

14.Visual inspection steps required for blast clean surfaces&Dry paint films ?

15. Conventional & Airless Spray System ?

16. Sequence of events leading to Clients Inspection ?

17 .Use of Electrostatic spray system ?

18. Functions of Primers, Midcoats, and Finish Coats ?

19. Client/ Contractor Relationship ?

20. Purpose of Working to quality Plan ?21. Factors which cause Poor Adhesion of Paint System?

22. Rust inhibitive properties of Paint system?

23. Recording of Information following Project Completion?

24. Explain Barrier &Sacrificial Coatings?

25. Environmental Testing: Paint Film Permeability Paint Film Flexibility

. Humid Environment , Marine Condition

26. Paint Faults: Blooming; Bleeding; Chalking; Cissing; Cracking; Grinning

Flocculation; Overspray; Osmotic Blistering.

Based on Practical.

1. Checks & Use of Whirling Hygrometer?

2. Calculation of Dew point &Relative Humidity ?.

3. Environmental limits for Painting Application?

4. Identification of Abrasives?

5. Identification of Rust grades &Blast cleaning grades?

6. Calibration of Dial micrometer?

7. Selection of a W.F.T. Comb Gauge& Reading of it?

8. Limits for Testex Tape?9. Reduction of Blast cleaned Surface?

10. Principle in which Banana gauge works? State the Calibration Procedure?

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1What is Corrosion/? What factors influence corrosion?

2. What is Mill scale? Why should it be removed?

3. List the items that are needed for open site blasting?

4. What factors determines the cleanliness of the steel surface?

5. What are the Rust grades Blast cleaning grades?

6. What is Paint? What does it contains? State the functions of .it?

7. Name four rust Inhibitive Primers?

8. What do you understand by C.P.V.C ?

9. State different methods of drying & curing give Examples of each?

10. What is a Tie-coat? What are laminar pigments, state their use?

11. What is B.S.2015? Explain Blistering, Chalking, Cisssing, Flocculation,

Grinning. Holidays.

12. What is Opacity? How do you measure it?

13. Define Viscosity? State a method to determine it?

14. What is Density? What is the use Density cup?

15. How do you select a wet comb gauge, for what it is used?

16. State the calibration procedure for a Banana Gauge? Explain the principle of it?

17. What is a Dolly test /18. State under what conditions Painting can proceed?

19. What are the main Responsibilities & Duties of Painting Inspector?

20. List Contractors Malpractices?

21. State the various methods of Paint Application? Briefly explain it?

22. What is a work permit? What do you understand by COSHH, HASWA?

23. Write the Formulae in which you use in Painting Works?

24. What information is needed before you undertake a maintenance Contract prior to

Coating?

25. What is not covered in BGPA10? What is BGPA9 /26. Define Dewpoint, Relative Humidity, Induction Period, Potlife, Flash point ?

27. What are the areas that need to be masked?

28. What Safety precaution to be followed in a Blasting &Painting Work?

29. How will you treat the surface affected by Algae Mould Growth?

30. What action will you do to rectify surfaces contaminated with oil?

31. What are the essentials things to consider on Maintenance Painting Job?

32. What is the use of SIS05 5900 & BS 4800, BS3900, BS5493, BS2569,

BS2842.BS7079

33. Describe the operations involved in S.P.A. 134. Why sealer is to be used? Explain a painting system for high temperature

services?

35. State the system for ferrous surfaces which are Damp?

2) Explain about scaffolding safety?

3) What are the main features to maintain good relationship between contractor

and client?

4) What are the sequences of activities you will follow for final client

inspection?

5) Explain the advantages of urethane paints?6) Explain the advantages of epoxy paints?

7) How will you reduce the risk at site?

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8) What kind of visual inspection to be done for cs before blasting preparations/

9) What visual inspection to be done for w.f.t.?

10) If blasted profile is higher than the standard how will you rectify?