Model Papers PDF

PAGE # 23.1 REVISION QUESTIONS

Corrosion OP – Monday 1 Is the electrical circuit in a corrosion reaction AC or DC?

D.C (Direct Current) 2 Does corrosion occur at the cathode or at the anode?

Anode 3 Name the three factors needed for corrosion to occur.

Anode, Cathode and Electrolyte 4 What is meant by the term electrolyte?

Electrolyte is a substance, which will conduct a current and be broken down by it. (Be dissociated by it) 5 What is corrosion?

Degradation of a material by chemical or Electro-chemical means 6 In the corrosion circuit do electrons flow from anode to cathode?

No 7 Which gas is released at the cathode when the electrolyte is water?

Hydrogen 8 Which is the more noble metal, steel or Aluminium?

Steel 9 Which is more electronegative, steel or Aluminium?

Aluminium 10 If steel and copper were in contact in an electrolyte which would corrode?

Steel 11 Name two common Hygroscopic salts.

Iron Chlorides, Iron Sulphates 12 Name three metals used as sacrificial anodes on a steel pipeline.

Magnesium, Zinc, and Aluminium 13 What is the approximate thickness of millscale?

From 25 to 100 Microns 14 Which of the two metals would corrode if steel and zinc were coupled?

Zinc

15 Which other names relate to the Galvanic List? Electro-Chemical Series, Electro Motive Force Series

16 In which environment are you likely to encounter chloride salts?

Marine Environments 17 Which three compounds together form millscale?

Wustite (FeO), Magnetite (Fe3 O4), Haematite(Fe2O3) 18 If magnesium was coupled with zinc, which would corrode?

Magnesium

Painting Inspection Grade 3/2. Rev 1 April 2004 WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY

Revision Questions 23.1 Copyright © 2003, TWI Ltd

19 In which environment would sulphate salts be found? Industrial (Power stations etc) and Agricultural areas

20 What is an osmotic blister?

Tiny, pinhead-sized, water-filled blister caused by hygroscopic salt contamination. (Iron sulphates / Iron Chlorides)

21 What is an ion?

A positively or negatively charged particle or atom. Unstable atom 22 What is meant by polarisation?

The polarity (negative or positive) of an atom 23 Is an anode positive or negative?

Positive 24 Can corrosion occur without an electrolyte?

No 25 Name a sub atomic particle.

Protons, Neutrons, and Electrons 26 What is millscale and when and where does it occur?

Compound of compressed oxides formed during steel rolling manufacturing operations at 580ºc, thickness 25 to 100µm.

27 Name three factors, which can accelerate corrosion reactions.

Temperature, Bacteria, Acids & Alkalines, Oxygen, Bi-metallic corrosion (galvanic list location), Hygroscopic Salts.

28 Why is it considered essential to remove millscale prior to painting?

It prevent Bi-metallic corrosion (millscale is more noble then the steel) and improves adhesion & cleanliness.

29 Why does an un-coated steel plate corrode?

Steel is heterogeneous, as it exits as both a cathode and anode simultaneously. Electrons enter at every available point of the substrate. Iron reacts readily with oxygen to form iron oxide (rust).

30 If corrosion occurs at anodic areas, why does steel corrode evenly all over the surface? Trace alloying elements in the steel (Nickel, carbon, Aluminium etc) provides millions of anodic and cathodic areas, (Bi-metallic contact) so the steel surface will corrode ( as it is both an anode and a cathode)



PAGE # 23.2 Surface preparation - Monday 1 Which British standard would be used in determining the size of copper slag abrasive?

BS.410 2 Which British standard would be used in determining the size of metallic abrasives?

BS.410 3 Which regulations prohibit the use of sand for blasting steel?

COSHH (MSDS or data sheets) & SI 1657 4 What is meant by the term ‘key’?

To improve adhesion to the surface

5 Why is it important to have good surface preparation? To improve adhesion & remove contamination.

6 What is meant by the term sliver? A surface breaking lamination.

7 What is a hackle? A sliver, which has been deformed upright after blasting.

8 Name two other terms that could be used for ‘anchor pattern’?

Peak to trough, key, Surface Profile & Amplitude 9 What are the main advantages of using ‘Testex papers’ for measuring profiles?

It provides a permanent record, and it can be used on curved surfaces 10 What is meant by the term grade, relating to a blast finish?

Degree of surface Cleanliness. 11 What are the main factors governing the grade of a blast finish?

Time spend, abrasive size, abrasive density, material density, Shape of particle, hardness of abrasive, initial rust grade

12 Can the grade of a blast finish be determined by using the surface comparators to BS 7079 Pt C3? No, only surface roughness

13 What profile range can be measured using X coarse Testex?

1.5 to 4.5 Thou” - 37-115 µm (Micron)

14 What profile range can be measured using coarse grade Testex? 0.8 to 2 Thou” – 20 to 50 µm (Micron)

15 What are the two theories of adhesion? Molecular Interference Molecular Attraction.

16 Briefly describe the mechanisms of the two theories of adhesion. Physical (e.g. Velcro) Chemical (e.g. Magnet)

17 How many microns are in 1thou? 25.4 µm

18 Give three different names for the cross section of a blast. Key, Surface Profile, Amplitude, Peak to trough, Anchor Pattern.



19 What is the approximate speed of abrasives leaving a venturi nozzle? 720 Km/h 450 m.p.h. (Miles per hour)

20 What is the most common cause of flash rusting on a blasted substrate?

Moisture

21 What would be considered to be an ideal shot grit mix? 70 - 80% shot / 20-30% grit.

22 What is the purpose of mixing shot and grit? Grit cuts the profile & shot control the peaks, to give a uniform profile.

23 Which abrasive would have the effect of work hardening a substrate?

Metallic shot or steel shot 24 Name three methods of measuring or assessing a profile.

Comparator, Visual, Touch(tactile), Surface Profile needle gauge, Dial micrometer & Replica Tape

25 What is the most common cause of rogue peaks on a substrate? Concentrated blasting in one area for too long.

26 In what situation would it be better to use steel grit in preference to copper slag abrasives?

Enclosed blast cabinets or ‘Wheelabrators’. 27 If cracks or laminations are found on a substrate after blasting what steps should be taken?

Stop the blasting operation and report it to the site Engineer for (ultrasonic lamination checks would normally follow)

28 Using comparators to ISO 8503, what are the three main profile assessments? Fine, Medium, Coarse

29 What are the other two assessments when the above three are not appropriate?

Finer then Fine, Coarser then Coarse 30 What would be size of copper slag needed to give a profile of 50 to 75 um?

G16 (J blast Supa is most common)



PAGE # 23.3 Surface preparation – Tuesday 1 What is the title of the BS 7079?

Preparation of steel substrate before application of paints and related products. 2 What are the four characteristics of an abrasive?

Size, Hardness, Density, Shape 3 Why are blast hoses carbon impregnated?

Static electricity discharge. 4 Name the gauge used for measuring pressure at the blast nozzle?

Hypodermic Needle Gauge. 5 Name four advantages of centrifugal blasting over open blasting.

Recyclable abrasives Operator safety Quality control No operator fatigue speed

6 According to BS 7079 is it possible to blast clean to an A Sa1?

No. 7 Is there any difference between an A Sa1 and B Sa1?

Yes. 8 Could you tell the difference between rust grades A and B blasted to Sa3?

No 9 Could you tell the difference between rust grades C and D blasted to Sa3?

Yes, possible heavy pitting. 10 What would be a typical speed of abrasives leaving a wheel abrator?

220 mph (Miles per hour). 11 What is considered to be the most efficient blasting pressure?

100 psi (Pounds per square Inch) 12 What is meant by the term “burnishing”?

Polishing or shining of the material surface 13 What would be the equivalent to St2 in the Sa grades?

Sa2½ (Stand alone grades) 14 What is the neutral figure on the pH scale?

Seven (7) 15 How is pH measured?

Potential Hydrogen – Litmus paper or pH indicator 16 Why are inhibitors sometimes added to water in wet blasting?

To prevent flash rusting (immediate oxidation). 17 Name two typical areas where needle guns might be used?

Rivets, Bolts, weld cap profiles, plate overlaps. 18 What is the Duplex Process of surface preparation?

Pickling followed by Passivation (Footners-Duplex system) blast clean to Sa 2½. 19 Which pH range covers acids?

0 to 7



20 Which pH range covers alkalies? 7 to 14.

21 What is the meaning of pH?

Potential hydrogen Iron 22 Name three disadvantages of wet blasting.

Disadvantages of wet blasting Wastage of lot of water Results in lot of Mud Creates light oxidation/flash rust

23 Name two areas on a structure where flame cleaning cannot be done.

Any area under tension (bolts, reverts, screw and nuts) 24 Which three basic operations are performed during flame cleaning?

Expansion Dehydration Heat penetration 25 How does BS 7079 define Flame Cleaning standards?

BS 7079 (ISO 8501) (SS 05 5900) AFL, BFL, CFL, & DFL.

26 What is a ‘Jasons Hammer’?

A Pneumatic caulking chisel. 27 What is meant by St2 and St3?

St2 “Thorough Hand and power tool cleaning” St3 “Very Thorough Hand and power tool cleaning”

28 Two alloys are used to render wire brushes spark free, what are they?

Phosphor Bronze and Beryllium Bronze. 29 Why should ‘Burnishing’ be avoided?

Polished surface gives very poor adhesion.

30 Name two major disadvantages of using a needle gun. Work hardening, operator fatigue, very coarse surface profile

31 After phosphating, what would be a typical pH requirement prior to coating?

4.5 to 7.0. 32 What is understood by the term ‘knock out pot’?

A small vessel with a drain tap, to remove oil and water vapour from the compressed air stream. 33 If an operator was blasting with a nozzle pressure of 80 psi. What would be his approximate

efficiency? 70% (80 psi = 20% x1.5efficiency drop = 30%)

34 Which solvents are commonly used for degreasing?

Xylene 35 What is a ‘dead mans handle’?

Safety cut-off triggers controlling the abrasive streams, which must be under the direct control of the blasting operator.

36 Why is carbon impregnated into blast hoses?

To avoid shock from static current. 37 How is abrasive cleansed in a wheel abrator system?

Air wash separator.



38 What is the main disadvantage of high pressure jetting compared to other systems? Safety, huge volume of water, slurry, no profile, flash rusting.

39 Name five methods of wet blasting. Steam, Air blasting plus water, high pressure, high pressure plus abrasive, low pressure plus abrasive.

40 What would be the typical temperature and concentration of Sulphuric Acid in the pickling process? 5-10% at 65% to 70% degrees

41 Describe the ‘Duplex Process’.

Degrease using Xylene. Check with Ultraviolet light. Immerse in 5-10% sulphuric acid for 5-25 mint at 65-70°c rinse with Clean warm water. Immerse in 1-2% phosphoric or Chromic acid, at 80°c for 1-2mins. With addition of 0.5% iron fillings. Rinse with clean warm water. Check pH level, to be between 4.5 and 7.0.

42 What would be a maximum pressure for high pressure water jetting?

30,000 psi (above this is said to be Ultra High Pressure). 43 What are the disadvantages of wet blasting over dry blasting?

Cut no profile, large amounts of slurry, large volume of water, flash rusting 44 Describe the phosphating process.

Same as duplex process

45 What would be considered to be advantages of wet blasting over dry blasting? Spark-free operation, removal of toxic detritus, removes Hygroscopic salts

46 Why is the phosphating or chromating of steel done?

Give limited protection against corrosion & prevent flash rusting. 47 What would be an acceptable remedy for burnished areas?

Emery cloth or Emery paper. 48 Would burnishing be expected on areas of St2 preparation?

No 49 How many photographs of blast cleaning standards are shown in BS 7079 Pt A?

14 Blast Cleaning standard



50 Do the plates shown in Bs 7079 Pt A relate to grit blasting or shot blasting? It refers to all types of abrasives

PAGE # 23.5 Paint technology (1) - Wednesday 1 Name a third type of paint other than solvent free and solvent borne.

Powder 2 An epoxy resin would use which solvent?

Acetone 3 Name four or more advantages of Chlorinated Rubber paints.

Durability, Flameproof, Resistant to algae / mould growth, Not reliant upon surface profile, water proof

4 What are the three main disadvantages of Chlorinated Rubber paint?

Poor resistance to HC solvents can not be made water-borne, low temperature tolerance. 5 Which solvent could be used with a Phenolic Resin?

White spirit

6 Chlorinated Rubber paint would contain which solvent? Xylene

7 Would it be good practice to apply Chlorinated Rubber over Alkyd resin?

No 8 Which solvent would be used with an Alkyd Resin?

White spirit 9 How was the word Alkyd derived?

It is derived from an Alcohol / Acid reaction. 10 What is meant by opaque?

Hiding or covering power. The ability to hide an underlying layer. 11 What is meant by vehicle?

Binder, Film former, Non Volatile 12 Would it be acceptable practice to apply an Alkyd over Chlorinated Rubber?

Yes. 13 Would it be acceptable practice to apply Chlorinated Rubber over Phenolic?

No. 14 Would it be acceptable practice to apply Phenolic Resin over Chlorinated Rubber?

Yes. 15 Would it be acceptable practice to apply Epoxy over linseed oil base?

No. 16 Would it be acceptable practice to apply Chlorinated Rubber over Epoxy?

Yes. 17 Would it be acceptable practice to apply Epoxy Resin over Alkyd Resin?

No 18 What is another name for an un-pigmented paint?

Varnish or lacquer



19 What are the natural properties of a Resin? Brittle & fast drying.

20 What are the natural properties of an Oil?

Slow drying & elastic 21 How does paint using the barrier principle work?

Physically prevents the electrolyte from making contact with the substrate. 22 How does paint using the passivation principle work?

Phosphates & Chromate react with iron, to create a layer of rust inhibitive Passivating salts. 23 How does paint using cathodic protection principle work?

By incorporating a metallic pigment of a lower nobility than the steel into the paint (Zinc & Aluminium). 24 Give another name for solvent free two packs.

Multi - Component Liquid or MCL. 25 Name six properties of a binder.

Resistant to abrasion / acid & Alkaline / water / electron, keep the pigment in suspension, cohesive / adhesive strength / change from liquid into a solid

26 Name three natural resins used in paints.

copal’s, dammars and coumarone, amber, laq. 27 Name five natural oils used in paints.

Linseed, Olive, palm, Castor, Coconut, Soya, 28 What does oleo resinous mean?

A mixture of Oil and Resins.

29 Name an Inorganic high temperature service binder. Silicates and Silicones



30 Name two pigments likely to be used for high temperature service. Zinc and Aluminum



PAGE # 23.6 Paint technology (2) – Wednesday 1 By what name would you call the basic unit of a polymer?

Mer Molecule, atom. 2 What is polymerisation?

The joining together of a string or structure of repeated units. 3 Name three types of polymers.

Linear Polymers Branched Polymers Cross Linked Polymers 4 What would be the characteristics of a short oil paint?

Less then 45% oil to resin, faster drying, suitable for steel work. 5 What would be the characteristics of a long oil paint?

More than 60% Oil to resins, elastic, slower drying, mainly decorative applications. 6 What is meant by the term “opaque pigment”?

Pigment with excellent “light scattering” properties, or “Hiding ability”. It is said to have “covering power”. 7 What is a typical size of a pigment particle?

0.1 to 1.0 (1/10th micron to 1) micron. 8 Briefly describe the difference between “saturated” and “unsaturated” when referring to oils or

polymers. Unsaturated oils will react with oxygen and solidify, Saturated oils will not, so they are classed as non-drying oils.

9 Name two drying oils, which are unsaturated.

Linseed, Tung, Soya, safflower, China Wood. 10 What is the main difference between a dye and a pigment?

A pigment must remain solid within the binder. (A dye will dissolve)

11 What are the sources of pigments? Animal, Mineral, Synthetic, Vegetable

12 If Titanium Dioxide was used in paint, what would be the colour?

White

13 Name three rust inhibitive pigments considered to be toxic. Red lead, Coal Tar, Zinc Chromate, Calcium Plumbate

14 Name four commonly occurring minerals used as extender pigments.

Talc Chalk, Slate Flour, China Clay 15 Name three laminar pigments.

MIO, Glass Flake, Graphite, Mica

16 If pigment was added way below the CPVC, how would it affect the film? Low Opacity, Blistering, Low Cohesive Strength, High Gloss.

17 The abbreviation CPVC means what?

CPVC stands for critical pigment volume concentration. 18 Why are thixotropes added to a paint formulation?

Anti-Setting agent, Thickener, Storage aid.



19 If carbon was used as a pigment what would be the paint colour? Black.

20 Name four properties that a binder contributes to a paint film.

Adhesion, ease of application, Dielectric strength, Cohesive strength, liquid to solid will keep the pigments is suspension, impermeability.

21 Describe how a basic inhibitor works.

A basic inhibitor reacts with the substrate to create rust inhibitive salts (phosphates & Chromates), to “passivate” the surface and make it less reactive to oxidation and corrosion.

22 Which of the common extenders could not be used in whites and pastels?

Slate flour 23 How would the film be affected if pigment was added above the CPVC?

Permeable / porous, Low Cohesive strength, Low Gloss, Low Adhesion. 24 Which of the rust inhibitive pigments is the most common?

Zinc Phosphate 25 Why are extenders used in paint formulation?

Add thickness and bulk at low cost, increase intercoat adhesion 26 If chromium was used as a pigment, what colour would the paint be?

Greens, Yellows and Oranges 27 Why are plasticisers added to paint?

Increase flexibility, reduces brittleness. Modifies the film properties. 28 Two metals are commonly used as galvanic pigmentation, name them.

Zinc and Aluminium. 29 Why are driers added to oil based paint?

To ensure even through thickness drying. (Prevent wrinkling & rivelling) 30 What is meant by the term ‘thixotropic’?

Thickener, Anti-Settling agent, aid to storage.

31 What is meant by the term ‘aggregate’ when referring to paint? Loosely adhering cluster of pigment and particle.

32 If an antioxidant was added to paint, what would it do?

Anti Skinning Agent. Prevents paint from forming a skin in the tin. 33 Give the names of two plasticizers.

Castor Oil, Coconut oil 34 What is meant by the term solution?

The resultant liquid after dissolving a solute in a solvent 35 Give two examples of a solution.

Saltish water (salt + water) Sweet water (sugar + water) 36 What is meant by the term dispersion?

A solid or liquid mixed in another liquid, where there is no solubility. 37 There are two types of dispersion, what are they?

Suspension and Emulsion



38 If paint cures by chemical reaction is it reversible or convertible?

Convertible 39 What type of polymerisation occurs in chemically curing paint?

Cross linked. 40 Name a paint, which dries solely by solvent evaporation.

Any linear polymer paints. (Chlorinated Rubber, Vinyl’s, Emulsions). 41 What is meant by ‘non convertible’?

Reversible. Can be returned to its original state if solvent is re-introduced or re-applied. 42 What is meant by ‘non reversible’?

Convertible. It is permanently altered to a new state after undergoing a chemical change. 43 Name four drying mechanisms.

Solvent evaporation, Chemical Curing, Oxidation, Coalescence. 44 In a coating, which dries by solvent evaporation, what type of polymerisation occurs?

Linear polymerisation. 45 What is another term for Fineness of Grind?

Degree of dispersion 46 Which generic types of paint dry by solvent evaporation followed by oxidation?

Natural Oils and Resins. 47 What type of polymer forms during oxidation?

Branched polymer

48 What term applies to paint drying at ambient temperatures? Air Drying

49 What is meant by the term ‘co-alescence’?

To physically join together. 50 What is meant by the term ‘pot life’?

The length of time (following induction) that a paint remains in an applicable condition according to the manufacturer's instructions.

51 Name three curing agents used in epoxies?

Amides, Amines and Isocyanates

52 Is paint a solution or dispersion, qualify? Dispersion, as the pigments must remain solid within the binder

53 What is an exothermic reaction?

A chemical reaction which is giving off heat 54 What is meant by the term ‘induction period’?

The length of time paint is required to stand after mixing and before application, to allow the air bulb to escape and or chemical reactions to take place and is specified by the paint manufacturer.

55 What is the difference between ‘thermoplastic’ and ‘thermosetting’?

Thermosetting coating will cure if heat is applied, and Thermoplastic coating will deform if heat is applied. 56 With a chemically curing paint, what type of polymerisation occurs?

Cross linking 57 Two other terms relate to induction period, what are they?

Stand time and Lead time.



58 Does a phenolic resin have an induction period? No. (Phenolic resins paints are not chemically using.)

59 Which of the following binders are reversible? a) Epoxy b) Phenolic c) Vinyl

d) Urethane e) Chlorinated Rubber f) Alkyd

g) Cellulose h) Silicone

60 Is an epoxy powder paint thermoplastic or thermosetting?

Thermosetting 61 If a coating is permeable, what does it mean?

It will allow the passage of moisture or electrolyte. 62 What is meant by cross-linking, give two binders as an example.

Multi directional polymerisation e.g. Epoxy, Urethane. 63 What is the opposite to exothermic?

Endothermic

64 What is the term used for paints needing temperatures in excess of 65oc to cure? Stove Drying.

65 What would be a typical induction period for Chlorinated Rubber paint?

None (Chlorinated rubber is not chemical curing). 66 Name a material used as a dryer in paint formulation.

Heavy metal salts (such as octoates or naphthanates of cobalt, manganese and zirconium) 67 Why would bentonite or wax be used in paint formulation?

Thickener, thixotropic agents, anti settling agent, non drip. 68 Name two materials used as plasticisers.

Coconut Oil, Castor Oil, Palm Oil. 69 What generic type of paints would use anti-oxidants?

Natural Oils and Resin. 70 How does a single pack, epoxy ester paint dry?

Solvent evaporation followed by oxidation. 71 How is Dewpoint defined?

The temperature at which condensation would form on a substrate. 72 How is Relative Humidity defined?

The amount of water vapour in the air expressed as a percentage and calculates from the wet and dry bulb temperatures.

73 When using a whirling hygrometer which bulb should be read first and why?

The Wet bulb should be read first, as it is artificially reduced and the temperature will gradually rise back to ambient.

74 At what speed should the thermometer bulbs pass through the air?

4m/sec (four meters per second), or as fast as possible. 75 What should be used when wetting the wick on whirling hygrometer?

De-Ionized or distilled water.



76 By what other name can we refer to a whirling hygrometer? Aspirated Psychrometer

77 When the air temperature rises does the air’s capacity to hold water increase or decrease?

Increases 78 What is the stated criterion for acceptance, prior to calculations, on a whirling hygrometer?

2 Consecutive identical readings (within 0.2 degrees) 79 Name two pieces of equipment used for taking steel temperature.

Limpet Gauge (Magnetic thermometer), Touch pyrometer.



80 Is it possible for a wet bulb temperature to be higher than the dry bulb?

No, never.

PAGE # 23.8 Paint testing – Thursday 1 Define viscosity.

A fluid’s resistance to flow 2 What is meant by high viscosity?

Very thick, and resisting flow. 3 Approximately, what is the viscosity of water?

one Centi- poise, or 1 dyne sec/cm²

4 Name the cgs and SI units of dynamic viscosity. CGS = poise, SI = (N.s/m2)

5 Name three different flow cups.

Ford, Zahn, Frikmar, ISO, ASTM 6 When using a flow cup which unit of viscosity would be used?

Seconds 7 In ‘Ford Flow Cup No 4’ what does ‘4’ relate to?

Diameter of the flow hole (4mm)

8 Give the names of three different rotational viscometers. Ford flow cup, Zahn, kerbs stormer, & Rotational Viscometer

9 Give a reason for performing a viscosity test on site.

Test to determine the addition of thinner, and mix ratio of multi packs. 10 Which viscometer would not be used on thixotropic paint?

Flow cups 11 Why is temperature very important when doing viscsity tests?

Viscosity will reduce at raised temperatures 12 What is the main difference between the rotathinner and Krebs Stomer?

Rotothinner is dynamic viscosity, kerbs stormer is Kinematics. 13 Describe how to use a Ford Flow Cup.

100cc of paint, level @ 20oc, scrape excess, allow to flow, measure in seconds until first break in continuous flow.

14 Give another name for a Fineness of grind gauge.

Hegman grind gauge. 15 Is a low flash point safer than a high flash point?

No. 16 How and for what is a Hegman grind gauge used?

To measure the degree of dispersion or fineness of grind 17 Briefly describe how to do the volatile, non-volatile test to BS 3900 Pt B2.

Weight gloss rod & plate, add 2g of paint, weight again, stir and place in oven to evaporate solvent. Remove and weigh again.

18 Name the equipment used to determine the flash point of a solvent.

ABEL cup



19 What colour should the flame be at the flash point? Blue

20 What formula is used to calculate the density? Density = Weight Volume

21 What formula is used to calculate specific gravity?

Density of product / Density of distilled water SG specific Gravity = Density of x Density of Water

22 What is relative density?

Density Compared to that of distilled water. 23 What are the other names for a density cup? Pyknometer. Weight per litre cup, density cup, SG cup, weight per gallon. 24 What is a stoke, the unit for?

kinematics viscosity. 25 Which test is used to determine Abrasion Resistance?

Erichson, Taber, Gardner. 26 Which equipment would be used to determine flexibility?

Conical mandrel. 27 Which equipment would be used to measure Impact Resistance?

Tubular impact tester 28 For what reason would the Koenig Albert Apparatus be used.?

hardness of paint film 29 For which two reasons could a density cup be used on site?

Check addition of thinner, correct mixing ratio 30 Name four accelerated test boxes.

Humidity Cabinet, Salt Spray Cabinet, Temperature cycling cabinet, Water soak test cabinets, Prohesion test 31 Why would a tropical box be used?

To test a paints ability to withstand accelerated tropical conditions. 32 Would a paint be higher or lower density than water?

Higher 33 How would the density be affected if solvent was added to paint?

Weight (density) would be reduced. 34 What is the capacity of a density cup?

100cc. 35 What difference is there between SG and Density?

Density has a unit (g/cc) SG is the measure of the density of the product / 100 36 What information could be obtained from a water soak test?

Water absorption



37 What information could be obtained from a temperature cycling test? Contraction and expansion cracking

38 What information could be obtained from a cold check test?

Contraction cracking. 39 Name four drying and curing tests.

Ballotini, BK stylus, mechanical thumb test, Wolff-wilbrone pencil scratch 40 What stage of the BK test would be recorded as the drying time?

When no scratch is evident whatsoever 41 Name three methods of determining opacity.

Pfund Cryptometer, Hiding power charts plus adjustable applicator, Black/White fused plates 42 What effects the opacity of a paint film?

Hiding ability is affected by CPVC 43 Why would a Pfund cryptometer be used?

To determine the minimum DFT required to provide covering of the underlying substrate. 44 Give one reason why an inspector would use a PIG gauge?

Check DFT and correct coating sequence. Check DFT over ferrous materials (MIO). Or to check DFT on Non Ferrous substrate.

45 Why are wet paint film thicknesses needed?

To calculate the DFT if volume solids is known, ensure correct DFT.

46 Name two methods of measuring WFTs Eccentric Wheel and Comb Gauge, biscuit gauge

47 What is the reason for taking WFTs immediately after application?

Prior to immediate solvent evaporation, to ensure correct calculation of DFT 48 Where could an inspector find information to determine if a 2 pack paint was mixed in the correct

proportions, using a density cup? Manufacturer’s data sheet

49 Can a banana gauge be used on non-ferromagnetic substrate? No.

50 Could an eddy-current gauge be used on ferromagnetic substrates?

No (Electromagnetic induction is used for ferrous) 51 Can a horseshoe gauge be used on non-ferromagnetic substrates?

No 52 As part of which test would a bar applicator be used?

Hiding power charts and bar applicator (opacity) 53 Which instruments would be used to measure reflectivity?

Gloss meter 54 How does a gloss meter work?

Measures the amount of received light from a known light source, at a given angle 55 Which factors in paint govern the degree of gloss?

CPVC, Binder type, Solvent type, refractive index, Degree of dispersion



56 In a primer/mid coat what would be the expected degree of grind? 40 microns

57 In a gloss paint what would be a typical degree of grind?

Occasionally 10 microns, but mainly 20 microns. 58 What percent reading would be expected when measuring gloss on a glass panel?

100% 59 Using a gloss meter a reading of 25% would signify what?

Matt 60 If an aggregate size of 35 um was present in a paint of 30 um DFT what would be a likely result when

using a gloss meter? Matt finish.

61 Name three common tests for determining adhesion of a paint film?

V cut test, Cross cut (Cross Hatch Test), Dolly, HATE (Hydraulic Adhesion test Equipment), V cut test.

62 Which adhesion tests are quantitative? Dolly, HATE (Hydraulic Adhesion Test Equipment)

63 Inter coat adhesion and primer to substrate adhesion are two adhesion faults name the third?

Cohesion failure

64 What chemical solution is used to conduct a Cathodic Disbondment test? 3% Saltwater

65 Which gas evolved at the cathode causes disbondment? Hydrogen

66 What criterion is used when assessing a Cathodic Disbondment test panel?

No more than 5mm damage outside of 6 mm diameter hole, after 28 days 67 Name the two methods of applying Cathodic Protection.

Impressed current, Sacrificial Anode. 68 What is used to determine the potential of a pipeline?

Copper / copper sulphate, half cell reference electrode 69 Would it be advisable to refill a pipe trench with carbonaceous backfill?

No, as the CP system would be nullified. 70 Does a Cathodic Protection System eliminate corrosion?

It control the “Location” and the rate of corrosion. 71 Can the external surface of a tank be protected?

No

72 Could a crude oil tank be fully protected internally? No only to the level of the tank contents

73 What voltage would be used on a 250 um thick paint using a sponge type pinhole detector?

9 Volts 74 What voltage would be used on a 450 um thick coating with a sponge type pinhole detector?

67.5 Volts 75 When using a wet sponge, what other liquid is added to the water?

Detergent



76 What function does the above additive perform? Reduce surface tension, water softener

77 Would it be advisable to do wet sponge detection on galvanising? No because zinc is conductive.

78 Why work upwards on a vertical surface with a wet sponge? To avoid incorrect or erroneous flaw locations owing to water seepage

79 Does a sponge detector work on AC or DC current?

Dc



80 Other than the wet sponge, which other equipment could be used to determine the presence of pinholes/holidays?

High voltage holiday detector using wire brushes. (Not Springs)

PAGE # 23.10 Revision questions general – Friday 1 Name two categories of paint mill.

Direct charge Mill, Premix mill, let down mill. 2 What is the main reason for processing paint in a mill?

Correct mix proportionate with requirements, fineness of grind. 3 Briefly describe how a ball mill works.

Steel Balls tumbled in a horizontal rotating drum, grinding the mill base. 4 Briefly describe how an attritor mill works.

Vertical drum with motorised paddles driving the steel balls. 5 When would steel balls not be used in a ball mill?

When producing lighter coloured paints. 6 A bead mill is sometimes called by which other names?

Sand Mills, Pearl Mill 7 How does a colloid mill work?

High speed stone discs bottom one rotating at 3600rpm, (revs per minute), top disc stationary. 8 Name eight items of information listed on a materials data sheet.

Application temperature Safety Application method and rate SG

Brand name and description Shelf life Binder type Solvent type Batch number Storage conditions

Colour Orifice/nozzle size Coverage Over coating time

VS% Drying time Flash point Induction period Pot life Mix ratio Recommended surface preparation.

9 What do you understand from the term Halogenated Hydrocarbon?

Iodine, Fluorine, Chlorine. 10 How can we determine the viscosity of a high viscosity paint?

Kerbs- stormer Viscometer 11 Briefly describe the principles of CP.

It controls the location and rate of corrosion by means of an impressed current. 12 What function does a primer have in a paint system?

Protects the substrate by means of Anti corrosion or scarification pigments 13 In a mordant primer what is the main working constituent?

Phosphoric Acid

14 What advantages do electrostatic application methods provide? Good edge cover, good transfer, low waste, uniform thickness.

15 Which is the most expensive type of brush filling?

Natural hair



16 What is cohesive failure in paint, give the main cause? Solvent entrapment, incorrect mixing ratio, too high CPVC.

17 Why does a zinc rich paint need a strong binder?

Good cohesive strength is required with zinc to provide sacrificial protection. 18 Why are etch primers not spray applied?

Toxic, Acid, and Environmentally unsafe. 19 What do you understand by the term over spray?

Accidental spray on undesired areas (nameplates, instrumentation etc). 20 Name four methods of determining DFTs.

WFT plus calculation, PIG, electronic Gauge, Banana Gauge, Horseshoe Gauge, Tinsley Pencil. 21 What is a psychrometer used for?

To measures WET bulb & dry bulb temperature. 22 What colour should a galvanised surface be after application of ‘T’ wash?

Black 23 How soon can a ‘T’ washed substrate be coated?

As soon as it is Dry. 24 Other than pigment, base and curing agent name two other constituents of FBE powder paint.

Anti foaming agent, Wetting Agent. 25 Give the main differences between airless and conventional spray.

Conventional gives Airless gives Better atomisation, high deposition rates, More accuracy, less waste layer better finish, faster, Easier cleaning, larger area coverage. Special container required,

26 Brush application has advantages over spray application, what are they? Small area Works paints into substrate Accuracy No overspray Accessibility Very low waste Environment friendly Thicker application Cheaper Prevents pinholes

27 What is the main consideration when selecting a metallic pigment for a sacrificial paint?

Its position in the galvanic list. 28 What is meant by shererdizing?

Items are tumbled in Zinc dust at a temp just below melting point.

29 Name three types of paint feed for a conventional spray. Suction, Gravity, remote pressure.

30 What is the calorising process?

Coating with Aluminium. 31 Why would a sealer be applied to Aluminium metal spray?

Yes for high temperature service to prolong protection. 32 What is the BS 2015 term for skipped or missed areas?

Holidays



33 A colour has three properties, what are they? Hue, Brightness and saturation.

34 Why would paint be applied by ‘hot spray’?

To reduce the viscosity. 35 On an airless spray tip how are blockages cleared?

Twist the nozzle. 36 How is atomisation achieved using conventional sprays?

Airstreams convergence outside of the Nozzle. 37 How is atomisation achieved using airless sprays?

Explosive force of high pressure paint meeting low pressure air. 38 What is dip coating?

Dipping the item in a tank of paint, allowing to dry. 39 What do you understand from the term ropiness?

Brush marks 40 What is efflorescence and how does it occur?

Soluble salt, normally deposited on concrete and mortar work. 41 Name two ways of melting aluminium to enable it to be sprayed.

Electric arc, Wire & pistol 42 What is flocculation?

Loosely clustered particles or aggregate often found in out of date paint. 43 What could be the cause of bittiness in a paint film?

Foreign bodies in the paints (grit, dust etc) 44 What is a tie coat?

A coat of paint applied to an area adjoining two incompatible coating systems. 45 How many depressions of the bellows are needed for the Dräger test?

Varies according to the relevant crystals required for the solvent under test.

46 What are the hazard signs for Toxic, Very Toxic, Harmful and corrosive? Black Skull & X bones, Black X, Dripping test tubes, steel block & hand

47 What is saponification?

The production of lead soap, when using basic primer with Natural Oil paints 48 What units are used for measuring toxicity?

Ppm (part per million) 49 Which material would have to be used on a perpetually damp surface?

Moisture curing Polyurethane 50 What is padding?

Use of a pad, coated in fine natural hair, to apply paint 51 What air inlet pressure is needed to give 2500 psi delivery with 35:1 pump?

71 psi 52 What causes lifting of a paint film?

Non-observance of over coating time, applying strong solvent over weak binder



53 What is cissing and how is it caused? Oil or grease contamination of the substrate, causing a local lack of adhesion

54 What is meant by the abbreviations: OES, OEL, MEL, UEL, LEL and RAQ?

OES, Occupational Exposure Standard OEL, Occupational Exposure Limit MEL, Maximum Exposure Limit UEL, Upper Explosive Limit LEL Lower Explosive Limit RAQ Required Air Quantity

55 Why would a paint inspector use potassium hexacyonoferrate?

Check for hygroscopic salt contamination 56 What would be an average thickness for galvanising?

100 µm 57 How can you tell the difference between blooming and chalking?

No 58 What could be the reasons for inter coat adhesive failure?

Incompatibility, contamination 59 How would you determine quality of added thinners in thixotropic paint?

Rotational Viscometer 60 Why are manufacturers developing solvent free, water borne and powders?

Environmental impact, cost 61 What would be the cause of grinning on a paint film?

Poor opacity, Low CPVC 62 How can ‘bleeding’ be avoided?

Total removal of Bitumen / Coal Tar coating prior to painting 63 In less than 30 words, explain the duties of a painting inspector.

Visually inspect paint finish, DP, RH,

Monitor against re-use of abrasives. Monitor complaint materials. Monitor inter coat time, painting sequence, Monitor addition of thinners, Measure and record surface profiles. Measure & record DFT, WFT, Measure & report wet bulb dry bulb,

Check surface condition & preparation. Check adherence to Pot life & Induction period. Check operation of blasting equipment (vapour traps earth cable, Control storage of paint and abrasives,

Record Weather condition & compliance with specification Report any non conformance to engineer.

Whiplash cables, External coupling etc) should have site plan and documentation. Administering adhesion tests

Preparation of Q panels or test plates



Prepare inspection report,

64 Name five documents, which a painting inspector might need on a contract. Contract specification, inspection reports, Operator qualifications, COSHH

65 What information should be given on a daily report sheet?

Air temperature WFT Colour code Abrasive type Wind speed Contract Abrasive supplier Weather condition Location Application date Wet bulb Time Abrasive size Blast grade Rust grade location. DFT Operator name RH Dew point Over coating time Report number Dry bulb Specification Paint batch number Expiry or shelf life date Standard Paint manufacturer Inspectors name and qualification Steel temp Paint system

66 Curtains, Sags, Runs and Tears are a result of what?

Excessive paint deposition 67 Some binders can be modified to use water as a solvent, name four.

Vinyls, acrylics, emulsion, alkyds, Bitumens 68 What is meant by the term stripe coat?

Brush applying a coat of paint where spray application may be inaccessible

69 How many cm3 are there in 4.5 litres? 4500



70 A paint data sheet provides a wealth of information, name eight items. Flash point Density VS% Health & Safety, Batch numbers Recommended thinners Drying time at 20ºc Recommended WFT Application method Contents Solvent type

PAGE # 23.12 Revision questions PA 10 specific 1 What is the specified course of action for grit inclusions?

Re-blast and re-coat 2 The term ‘long term protection’ refers to what?

Protection lasting typically 10 years 3 What is the difference between new and weathered galvanising?

Weathered surface provides its own key, and requires only stiff bristled brush for preparation 4 What criterion determines which paint system should be used?

The compatibility with the existing coating system, and must be in accordance with PA 10 5 What is the total DFT of the compliant epoxy system?

265 microns minimum 6 What is the total DFT of the water borne system?

225 microns minimum 7 When can ladders and other means of access be removed?

When all operations (including final acceptance) have been completed 8 Two materials are specified for used on damp surfaces, what are they?

Moisture Curing Polyurethane, and solvent free epoxy 9 After removal of a non-drying paint, which type of primer is recommended?

White spirit based primer 10 Some non-ferrous substrates are painted for aesthetics only, name four.

Stainless steel, Concrete, Fibre Glass, Aluminium 11 Which three non-ferrous substrates are painted for anti corrosion purposes?

New and weathered galvanized, aluminium 12 According to PA 10 in which situations would ‘T’ wash be used?

New Galvanised Steel, where sweep blasting or hand abrasion in inadvisable or impractial 13 How many coats of primer are specified on surfaces at 100 – 149oc?

As many as required 14 Give preferential order of coating systems for surfaces 150 – 340oc.

TSA, IZS & Polysiloxane inorganic coating 15 Is it mandatory for a contractor to produce a test area?

Not mandatory, but generally upon request 16 List four items needing masking off prior to blasting and painting.

Name plates, instrumentation, vents, monitoring panels 17 Which Aluminium substrate would not be sweep blasted?

Thin aluminium plate 18 Which three paint systems are specified for use on Aluminium?

Water-Borne Acrylic, High Build Epoxy, Alkyd or modified Alkyd



19 What differences are there in new and maintenance painting specifications for substrates below 100oc? They are both covered by one specification = PA 10

20 Toxic coatings need special considerations for removal from substrates, name two methods which comply. Needle gun, Water jetting, Water plus abrasive

21 In which situations is a Permit to Work required?

All BGas installations (live sites) 22 Which primers are specified for non-weathered galvanising?

Wash Primers, such as T-Wash 23 Which primers are specified for weathered galvanising?

Primer not required, initial coat MIO 24 According to PA 10 is flame cleaning allowed?

No, not on live Gas sites 25 According to PA 10 is thinning of paint allowed?

Yes, but only in accordance with the manufacturers data sheet 26 What temperature range is covered by ‘hot duty service’?

Above 100ºc 27 Does PA 10 cover internal coatings on pipes?

No, BGC/PS/PA8 covers this 28 What is the specified overlap on repair areas?

100mm onto sound coating 29 What would be the specified surface preparation and coating system for Aluminium cladding?

Etch primer 30 What would be the procedure for removal of algae and mould?

Treat with a biocidal agent for 24 hours, and then scrub with stiff bristle brush and water jetting

31 What would be the procedure for degreasing prior to surface preparation? Oil, grease, salts removed by washing with appropriate solvent (5.9.1.6)

32 What would be the procedure for degreasing after to surface preparation?

Any oil grease shall be removed by washing with clean water and dry (5.9.6.4) 33 When blast cleaning on an AGI what precautions are taken?

Abrasive blast cleaning should comply with current safety regulations (5.9.2.1) 34 Is it permissible to prepare paint by stirring?

Only below 5 litres mechanical methods preferred

35 What would be the surface preparation method for new galvanising? Sweep blast (Sa 1)

36 When would it be necessary to apply a sealer to inorganic zinc silicate?

When long term protection is required 37 How could areas of a paint breakdown be prepared for repainting?

Sweep blasting, emery paper 38 What information should be on a paint can label for BG?

Hazard warning symbol, batch number, paint type, colour



39 When measuring DFTs over galvanising what allowances are made? Deduct the thickness of the zinc, generally 100 microns

40 What is the first coat applied to galvanised substrates and why? MIO, primer is not required

41 Properties and Performances of paint are covered in which BG specification?

BGC / PS / PA9 42 What are the considerations when selecting a paint system?

Existing coating if any (compatibility), surface temperature, environment, lifetime expectancy, cost, cleaning methods available, specification requirements

43 According to PA 10 which two coats are applied ‘at works’?

Primer and MIO 44 Give the criterion for when and when not, painting can take place.

Max. 90% Relative Humidity, Steel & Air Temperature to be 3°c above Dew point 45 What should be the substrate reaction when ‘T’ wash is applied to a newly galvanised substrate?

The substrate turns black 46 Which two materials are specified for use on damp surfaces?

Moisture Curing Polyurethane, Solvent Free Epoxies 47 What is the maximum time lapse from surface preparation to coating?

4 Hours 48 Which is the most common pigment used in high temperature paints?

Silicone 49 What would be the result of over thick application of zinc silicate?

Mud Cracking



50 According to PA 10 is roller application permissible? PA 10 states that roller application is not recommended

PAGE # 23.14 B. Gas 3.2 Maths Exercises WFT calculations 1 What WFT would need to be applied to give a DFT of 45 um using a paint of 56% vs?

80.35µm

2 What WFT would need to be applied to give a DFT of 60 um using a paint of 40% vs? 150 µm

3 A paint of 38% vs was used to give a DFT of 45 um what wad the WFT?

118.4 µm 4 A DFT of 55 um was obtained from a paint of 55% vs, what was the WFT applied?

84.62 µm 5 What WFT would be applied to leave a DFT of 65 um using a paint of 49% vs?

132.65 µm DFT calculations 1 What would be the DFT if 20 litres of paint, vs. 45% covered an area of 9m x 12m? 2 25 litres of paint, vs. 65% was used to cover a circular area of 10m diameter. What would be the

resulting DFT? 3 What DFT would be obtained if a paint vs content 42% was applied at a WFT of 84 um? 4 What would be the resulting DFT if a WFT of 130 um, what would be the resulting DFT? 5 A paint, vs 65% was applied at a WFT of 130 um, what would be the resulting DFT? VS calculations 1 A DFT of 53 um was obtained from a WFT of 110 um, what was the vs% of the paint? 2 A paint was applied at 120 um WFT. The resulting DFT was 65 um, what was the vs%?



3 What would be the vs% of a paint if it was applied with a WFT of 120 um and a DFT of 68 um was obtained?

4 What was the vs% of a paint with a DFT of 36 um, when the WFT was 108 um? 5 A DFT of 62 um was measured, from a WFT application of 100 um, what would be the vs% of the

paint used? Volume calculations 1 What volume of paint would be required to cover an area of 300 square metres, to a specified DFT of

65 um, using a paint of 45% vs? 2 How much paint would be required to coat a tank, roof and side sheets to a DFT of 100 um? The tank

is 5 metres diameter and 6 metres high. The paint to be used is solvent free. 3 How much paint would be needed to cover a circular area of 10 metres diameter, using a paint 65% vs

to a DFT of 60 um? 4 A circular area of 7 metres radius is to be coated to a DFT of 45 um. What volume of paint would be

required if the vs content was 48%? 5 How much paint would be needed, at 55% vs, to coat an area of 250 square metres to a DFT of 60 um?



Density and SG exercise 1 What would be the weight of 16.5 litres of paint with a SG of 1.45? 2 What is the density of a paint if 7.5 litres weighs 9.75 kg? 3 What would be the relative density of paint in question two? 4 If the weight of 25 litres of paint is 37.5 kg, what would be the SG? 5 A 2 pack epoxy should be mixed at one part base to one part activator, the base has a density of

1.4gm/cc and the activator 0.9 gm/cc. What would be the density of the mixed components? 6 A 2 pack paint is mixed at a ratio of six parts pack A (density 1.3gm/cc) to one part pack B (density

0.9gm/cc). What would be the density of the combined parts? 7 A mixed 2 pack paint has a density of 1.35gm/cc. The density of the base was 1.5gm/cc and the

activator 0.9gm/cc. The mixing ratio was 3:1. Has the paint been mixed correctly? 8 A mixed 2 pack paint has a density of 1.35gm/cc. Mixed at a ratio of 6:1, base density 1.45gm/cc,

activator density 0.95gm/cc. Has the paint been mixed correctly?



RH and DP exercise



WB DB DP RH Steel Temp. Y/N 1 10 12 13 2 9 10 11 3 4 6 6 4 5 7 6.5 5 11 12 12 6 14.5 15.5 16 7 9.5 10.5 11 8 12 16 17 9 12 13 13 10 13 13.5 14 11 17.5 21 23 12 14 17.5 17 13 11 11 11.5 14 7.5 8.5 8 15 7 6 7 16 6.5 8 11 17 2 3 3 18 13 15 16 19 8 8 8 20 16 18.5 19 21 17 18 18 22 8 9.5 10 23 22 24.5 24.5 24 16 16.5 19 25 3 4 5 26 7 8 9 27 19 18 20 28 12 12.5 13 29 14 16.5 16.5 30 8.5 11 11

Whirling hygrometer Limpet Gauge ( Magnetic contact wait 15 min before reading) Thermocouple (Electronic, contact, Immediate reading) Density (The Density (SG) cup Flash Point of solvent ( ABEL Closed Cup) Higman Grind Gauge (for fineness of grind, Degree of dispersion)

Painting Inspection Grade 3/2 1 Appendix C

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