CHAPTER 23 REVISION QUESTIONS CORROSION
(Answer of question from course notes) Q 01- Is the electrical circuit in a corrosion corrosion reaction AC or DC? Ansns-
Direct Cur Current (DC)
Q02Q02- Does Does corr corrosi osion on occur occur at the the cathode cathode or anode anode?? AnsAns- Corr Corros osio ion n occur occurss at Anod Anodes es Q03- Name the the three three factors factors needed for corros corrosion ion to occur. Ans- The three three factor factorss required required for corros corrosion ion is is Anodes, Anodes, Cathodes Cathodes and and Electroly Electrolyte. te. Q04Q04- What What is meant meant by the term term elec electro trolyt lyte? e? Ans- Electrolyt Electrolytee is a substance substance which will conduct a current current and be broken down by its. Q05Q05- What What is corr corros osio ion? n? Ans-
Corrosion Corrosion is degradat degradation ion of metal by a Chemical Chemical or Electrochemi Electrochemical cal means. means.
Q06Q06-
In the the corros corrosion ion circu circuit it do elec electro trons ns flow flow from from anode anode to cath cathode ode??
AnsAns-
Electr Electrons ons flow flow from from Cathod Cathodes es to Anodes Anodes..
Q07- Which gas is is released released at at the cathode cathode when the electroly electrolyte te is water? Ans-
Hydrogen ga gas.
Q08Q08-
which which is is more more noble noble metal metal,, steel steel or or alumi aluminiu nium? m?
Ans-
Steel.
Q09Q09-
Which Which is more more elect electron ronega egativ tive, e, steel steel or alum alumini inium? um?
Ans-
Aluminium.
Q10- If steel steel and copper copper were were in contact contact in electr electrolyte olyte which would corrode? corrode? Ans-
Steel.
Q11Q11- Name Name two two com commo mon n hygr hygros osco copi picc salt salts. s. AnsAns-
Iron Iron Sulp Sulpha hate te and and Iron Iron Chlo Chlori ride des. s.
Q12- Name three metals used as as sacrif sacrificial icial anode on a steel steel pipeline. pipeline. Ansns-
Zinc, Alloy and Magn agnesium.
Q13Q13-
What What is the the approx approxima imate te thick thicknes nesss of mills millscal cale? e?
Ans-
25 - 100µ m.
Q14- Which of the the two metals metals would would corrode corrode if steel and zinc were coupled? coupled? Ansns-
Zinc wi will cor corrrode ode.
Q15Q15-
Which Which other other names names rela relate te to the the Galv Galvani anicc list? list?
AnsAns-
Galvan Galvanic ic Seri Series, es, Electro Electroche chemic mical al Serie Seriess and Electr Electromo omotiv tivee Force Force Series Series..
(Monday)
Q16Q16-
In which which envi environ ronmen mentt are you you likely likely to encou encounte nterr chlor chloride ide salt? salt?
Ans-
Marine’s environment.
Q17Q17-
Which Which three three comp compoun ounds ds togeth together er form form mills millscal cale? e?
AnsAns-
Wust Wustit ite, e, Magn Magnet etit itee and and Hema Hemati tite te..
Q18Q18-
If magne magnesiu sium m was coupl coupled ed with with zinc, zinc, which which would would corrod corrode? e?
Ans-
Magnesium.
Q19Q19-
In which which envi environ ronmen mentt would would sulph sulphate ate salt salt be be found? found?
AnsAns-
Indus ndustr tria iall and and agri agricu cult ltur ure. e.
Q20Q20- what what is an osmo osmoti ticc bli blist ster er?? AnsAns-
Dome Dome shape shape projec projectio tion n cause causess by Hygros Hygroscop copic ic Salts. Salts.
Q21-
What is an ion?
AnsAns-
Positi Positively vely or negativ negatively ely charge charge atom. atom.
Q22Q22- What What is is mean meantt by polar polariza izati tion on?? AnsAns-
Curr Curren entt eith either er posi positi tive ve or or nega negati tive ve ( DC DC + or or DC DC - )
Q23Q23- Is an an anod anodee posi positi tive ve or neg negat ativ ive? e? Ansns-
Positive Charge.
Q24Q24-
Can corros corrosion ion occur occur withou withoutt an electr electrolyt olyte? e?
Ans-
Cannot, Cannot, because because three three factors factors needed needed for corro corrosion sion to occur, anodes, anodes, cathodes cathodes and electr electrolyte. olyte.
Q25Q25- Name Name a sub sub atom atomic ic parti particle cles. s. AnsAns-
Prot Proton on,, Ele Elect ctro ron n and and Neut Neutro ron. n.
Q26Q26-
What What is mill millsca scale le and and when when and and where where does does it it occur? occur?
AnsAns-
Millsc Millscale ale is combin combinati ation on of oxides oxides layers layers on steel steel surfac surface, e, formed formed togethe togetherr during during rollin rolling g proces processs of steel steel at high high tempera temperatur turee with with approxim approximate ate thick thicknes nesss 25 - 100µm.
Q27- Name three factors, factors, which which can accelerate accelerate corrosion corrosion reactions. reactions. Ans-
Temperature, Temperature, Hygroscopic Hygroscopic Salts, Salts, Aerobic Aerobic Condition, Condition, Bacteria, Bacteria, acid acid and and alkalis. alkalis.
Q28- Why is is it considered considered essent essential ial to to remove remove millscal millscalee prior prior to painting? painting? Ans-
Because Because the nobility nobility between between steel steel and mill mill scale, scale, mill scale scale more more noble than than steel steel and mill mill scale is is easily flack off if temperature applied and will lack of adhesion adhesion due to different expansion.
Q29Q29-
Why does an uncoa uncoated ted steel steel plat platee corrod corrode? e?
AnsAns-
Becaus Becausee of thre threee elemen elements ts for for corro corrosio sion n was there. there.
Q30- If corrosi corrosion on occurs occurs at anodic anodic areas, areas, why does steel steel corrode corrode evenly evenly all all over the surface? surface? AnsAns-
Beca Becaus usee ther theree is no no prote protect ctio ion n at the the ste steel el..
CHAPTER 23 REVISION QUESTIONS
(Monday (Monday)) Sht 2
SURFACE PREPARATION (Answer of question from course note) Q01- Which Britis British h standard standard would would be used used in determini determining ng the size of copper slag slag abrasive? abrasive?
Ans-
BS 410.
Q02- Which Britis British h standard standard would would be used used in determini determining ng the size of metallic metallic abrasives abrasives?? Ans-
BS 410.
Q03- Which regulations regulations prohibit prohibit the use of of sand sand for for blastin blasting g steel? steel? Ansns-
COSH COSHH H reg regul ulat atio ion n
Q04-
What is meant by the term ‘key’?
AnsAns-
Cros Crosss sect sectio ion n of Blas Blasti ting ng Prof Profil ile. e.
Q05Q05-
Why is is it import important ant to have have good good surfac surfacee prepara preparatio tion? n?
AnsAns-
To remove remove cont contami aminat nation ion for for bette betterr adhesio adhesion n between between a paint paint and the the subst substrat rate. e.
Q06-
What is meant by the term ‘silver’?
Ans-
Lamination Lamination or crack, crack, appear appear to to be a longit longitudinal udinal crack, which one lip curling curling back. back.
Q0707-
what what is a hack hackle le??
Ans-
A small small surface surface lamination lamination which stand upright upright like like a needle needle after after blasti blasting. ng.
Q08- Name two other terms that could be used for ‘anchor pattern’? AnsAns-
Prof Profil ile, e, Key, Key, Pea Peak k to thro throug ugh h heigh height. t.
Q09-
What are the main advantages of using usin g ‘Testex papers” for measuring profiles?
AnsAns-
Test Testex ex pape papers rs can can be keep keepin ing g as a per perma mane nent nt reco record. rd.
Q10Q10-
What What is meant meant by the grade grade,, relati relating ng to a blast blast fini finish? sh?
AnsAns-
Degr Degree ee of clea cleanl nlin ines ess. s.
Q11Q11-
What What are the main main fact factors ors gover governin ning g the grade grade of a blas blastt finish finish??
Ans-
Dependant Dependant on on the time spent on the the area area and velocity of the the particle particles. s.
Q12- Can the the grade grade of a blast finish finish be determ determined ined by using the surface surface comparators comparators to BS7079 BS7079 Pt C3? C3? Ans-
Cannot, Cannot, surface surface comparator comparator used used for assess assess degree degree of of roughnes roughnesss only. only.
Q13Q13-
What What profil profilee range range can be measur measured ed using using X cours coursee Testex Testex??
Ans-
40 - 115µ m. m.
Q14- What profile profile range range can can be measured measured using using course course grade Testex? Testex? Ans- 20 - 50µ m. m. Q15Q15- What What are are the the two two theo theori ries es of of adhe adhesi sion? on? AnsAns-
Molecu Molecular lar Attrac Attractio tion n and Molec Molecula ularr Interf Interfere erence. nce.
Q16- Briefly Briefly describ describee the mechanisms mechanisms of the the two two theories theories of adhesio adhesion. n.
Ans-
Molecular Attraction – negatively charge particle attracted to positively areas and vise versa (analogy magnet ) Molecular Interference – Because the surface is rough and uneven the paint wets and lock into the profile (analogy Velcro/physical).
Q17-
How many microns are in 1 thou?
Ans-
25.4µ m.
Q18- Give three different names for the cross section of a blast. Ans-
Blast profile, anchor pattern and amplitude.
Q19- What is the approximate speed of abrasives leaving a venturi nozzle? Ans-
450 mph.
Q20- What is the most common cause of flash rusting on a blasted substrate? Ans-
Moisture.
Q21-
What would be considered to be an ideal shot grit mix?
Ans-
20 – 30 % Grit to 70 – 80 % Shot.
Q22-
What is the purpose of mixing shot and grit?
Ans-
To create more uniform profile which Grit cut a profile and a Shot will control peak to through height.
Q23-
Which abrasive would have the effect of work hardening?
Ans-
Steel Shot.
Q24-
Name three methods of measuring or assessing a profile.
Ans-
Surface Profile, Needle Gauge, Dial Micrometer and Replica Tape and Surface Comparator.
Q25-
What is the most common cause of rough peak on substrate?
Ans-
Blast to long time at a same area.
Q26- In what situation would it better to use steel grit in preference to copper slag abrasives? Ans-
Factory and confine space.
Q27- If crack or laminations are found on a substrate after blasting what step should be taken? Ans-
Refer to the Engineer for His/Her discretion.
Q28- Using comparators to ISO 8503, what are the three main profile assessments? Ans-
Fine, Medium and Course.
Q29- what are the other two assessments when the above three are not appropriate? Ans-
Finer than Fine and Coarser than Coarse.
Q30-
What would be size of copper slag needed to give a profile of 50 to 75 ụ m
Ans-
Garnet size 3060. (G16)
SURFACE PREPARATION
(Tuesday)
(Answer of question from course note) Q01- What is the title of the BS 7079? Ans-
Preparation of steel substrate before application of paints and related product.
Q02-
What are the four characteristics of an abrasive?
Ans-
Size of particles, hardness, density and shape of particle.
Q03-
Why are blast hoses carbon impregnated?
Ans-
To remove or reduce electric static shock.
Q04-
Name the gauge used for measuring pressure at the blast nozzle?
Ans-
Hypodermic Needle Gauge.
Q05- Name four advantages of centrifugal blasting over open blasting. Ans-
Long production run, Can control quality, more safety, efficient use of abrasive.
Q06-
According to BS 7079 it is possible to blast clean to an A Sa1?
Ans-
Impossible.
Q07-
Is there any difference between an A Sa1 and B Sa1?
Ans-
Yes, the appearance.
Q08- Could you tell the difference between rust grades A and B blasted to Sa3? Ans-
No different.
Q09-
Could you tell the difference between rust grades C and D blasted to Sa3?
Ans-
Yes, Rust grade D have a heavy pitted.
Q10- What would be a typical speed of abrasives leaving a wheel abrator? Ans-
220mph.
Q11- What is considered to be the most efficient blasting pressure? Ans-
100psi per nozzle.
Q12-
What is meant by the term “burnishing”?
Ans-
Burnishing is a result of over brushing, smooth and shiny areas which does not provide good
adhesion. Q13-
What would be the equivalent to St2 in the Sa grade?
Ans-
SA 1
Q14- What is the neutral figure on the pH scale? Ans-
7pH
Q15- How is pH measured? Ans-
Using pH indication strip paper.
Q16- Why are inhibitor sometimes added to water in wet blasting? Ans-
To retards the formation of corrosion product.
Q17-
Name two typical areas where needle guns might be used?
Ans-
Rust Grade A and D.
Q18-
What is the Duplex process of surface preparation?
Ans-
Pickling process followed by passivation process.
Q19- Which pH range covers acids? Ans-
0 till 7pH. Acid.
Q20- Which pH range covers alkalies? Ans-
7 till 14pH Alkalines.
Q21- What is the meaning of pH? AnsQ22-
Name three disadvantages of wet blasting?
Ans-
Supply a large amount of water, disposal of slurry and mix of inhibitor.
Q23- Name two areas on a structure where flam cleaning cannot be done? Ans-
Revert, screw, bolt and nuts.
Q24- Which three basic operations are performed during flame cleaning? Ans-
Expansion, Dehydration and Heat penetration.
Q25-
How does BS 7079 define flam cleaning standards?
Ans-
AF1, BF1, CF1 and DF1.
Q26-
What is ‘Jason Hammer?
Ans-
Type of a needle gun.
Q27- What is meant by St2 and St3? Ans-
St 2 means thorough hand and power tool cleaning St 3 means Very thorough hand and power tool cleaning.
Q28- Two alloy are use to render wire brushes spark free, what are they? Ans-
Phosphorus Bronze and Beryllium Bronze.
Q29-
Why ‘Burnishing’ be avoided?
Ans-
Burnishing did not provide a good adhesion of paint.
Q30-
Name two disadvantages of using needle gun.
Ans-
Leave a very coarse profile and, work harden need.
Q31- After phosphating, what would be a typical pH requirement prior to coating? Ans-
4.5 Till 7pH.
Q32-
What is under stood by the term ‘Knock out pot?
Ans-
Oil or water filter/separator.
Q33- If an operator was blasting with a nozzle pressure of 80 psi. What would be his approximate efficiency? Ans-
70% production.
Q34-
Which solvents are commonly used for degreasing?
Ans-
Xylene.
Q35- What is the dead mans handle? Ans-
Blasting Triggers which always under operator control.
Q36-
Why is carbon impregnated in to blast hose?
Ans-
To remove or reduce the electric shock.
Q37-
how is abrasive cleansed in a wheel abrator system?
Ans-
By Air Wash Separator
Q38- What is the main disadvantage of high pressure jetting compared to other systems? Ans-
Because of high pressure it’s very hazardous to the operator.
Q39- Name five method of wet blasting. Ans-
High pressure water blasting up to 30000psi, High pressure water plus abrasive injection, and low pressure water plus abrasive injection and Water Blasting.
Q40- What would be typical temperature and concentration of sulfuric Acid in the pickling process? Ans-
5 to 10% Concentration and 60 to 70°C Temperature.
Q41-
Describe the ‘Duplex processes’.
Ans-
After Pickling Process complete, immerse the steel substrate into a bath of phosphoric/Chromic acid, 2 % solution at 80°C for approximately one to two minute with iron filling (0.5%) and after that rinse in clean water and check for Ph values. Value should be at the range of 4.5 till 7pH.
Q42- What would be maximum pressure for high pressure water jetting? Ans-
30000 Psi.
Q43- What are the disadvantages of wet blasting over dry blasting? Ans-
Lot of slurry, use large amount of water and use inhibitor.
Q44- Describe the phosphating process? Ans…………………………………………………………………………………………………………… ……. ………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………
………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… ………………………………………… Q45- What would be considered to be advantage of wet blasting over dry blasting? Ans-
Spark free, environmentally friendly, remove hygroscopic salt, and reduce dust.
Q46-
Why is the phosphating or chromating of steel done?
Ans-
To forms rust inhibitive layers, which passivate the surface and increase the adhesion properties and also extremely resistant to cathodic disbondment.
Q47-
what would be an acceptable remedy for burnished area?
Ans-
Treated by abrading with emery clothes.
Q48-
Would burnishing be expected on areas of St2 preparation?
Ans-
Yes
Q49- How many photographs of blast cleaning standards are shown in BS 7079Pt A? Ans-
14 photos, 2 for rust grade A and 4 photos for each rust grade B, C and D.
Q50- Do the plates shown in BS 7079 PtA related to grit blasting or shot blasting. Ans-
No it is related to all blasting.
PAINT TECHNOLOGY (1)
(Wednesday) Q01- Name a third type of paint other than solvent free and solvent born. Ans-
Powder paint.
Q02-
An epoxy resin would use which solvent?
Ans-
Ketones / Acetone.
Q03-
Name four or more advantages of Chlorinated Rubber paint.
Ans-
High resistance to mould growth, Non-flammable, Resistance to chemical attack, Non toxic and easy maintenance.
Q04- What are the three main disadvantages of Chlorinated Rubber paint? Ans-
Low resistance to some solvent, low temperature tolerance (65°C maximum) and spray application resulted in ‘cobwebs’
Q05-
Which solvent could be used with a Phenolic Resin?
Ans-
White Spirits.
Q06-
Chlorinated Rubber paint would contain which solvent?
Ans-
Xylene. Chlorine.
Q07- Would it be good practice to apply Chlorinated Rubber over Alkyd resin? Ans-
No, CR contain with strong solvent and Alkyd contain with weak solvent, if CR applied over Alkyd its will result a lifting.
Q08-
Which solvent could be used with an Alkyd resin?
Ans-
Aliphatic Hydrocarbon / White spirits.
Q09- How was the word Alkyd derived? Ans-
Alkyd derived from words of Alcohol and Acid reaction.
Q10- What is meant by opaque? Ans-
Inert particles with excellent light scattering properties in order to give covering power, opacity and colour.
Q11- What is meant by vehicle? Ans-
Binder is the main constituent of the paint; other terms are Carrier, Film former, non volatile.
Q12-
Would it be acceptable practice to apply an Alkyd over Chlorinated Rubber?
Ans-
Yes, weak solvent binder over strong solvent binder not creates any paint fault. I.e. lifting.
Q13- Would it be acceptable practice to apply Chlonirated Rubber over Phenolic? Ans-
Not acceptable, strong solvent over weak solvent will spoil the paint system. I.e. lifting.
Q14- Would it be acceptable practice to apply Phenolic Resin over Chlorinated Rubber? Ans-
Acceptable, weak solvent binder over strong solvent binder not creates any paint fault. I.e. lifting.
. Q15- Would it be acceptable practice to apply Epoxy over linseed oil base? Ans-
Acceptable, weak solvent binder over strong solvent binder not creates any paint fault. I.e. lifting.
Q16- Would it be acceptable practice to apply Chlorinated Rubber over Epoxy? Ans-
Not acceptable, strong solvent binder over weak solvent binder will spoilt the paint system. I.e. lifting.
Q17- Would it be acceptable practice to apply Epoxy Resin over Alkyd Resin? Ans-
No
Q18-
What is other name for an un-pigmented paint?
Ans-
Dye and varnish. Lacquer
Q19-
What are the natural properties of a Resin.
Ans-
Very brittle, fast dry and can not mixed with water.
Q20-
What are the natural properties of an Oil?
Ans-
Slow drying, flexibility.
Q21-
How does paint using the barrier principle work?
Ans-
Forms thick impermeable layer of high electrical resistance, applied over primer coat, to prevent from water passing into the film and leaching out the inhibitive pigmentation.
Q22-
How does paint using the Passivation principle work?
Ans-
Causing a chemical reaction between the paint constituent and the substrate.
Q23-
How does paint using cathodic protection principle work?
Ans-
By sacrificial coating.
Q24-
Give another name for solvent free two packs.
Ans-
Multi Component Liquids paints and Chemical curing materials.
Q25- Name six properties of a binder. Ans-
Ease application, adhesion to substrate, abrasion resistance, chemical resistance, cohesive strength and ability to resist the passage of water.
Q26-
Name three natural resins used in paints.
Ans-
Copal, dammar and coumarone.
Q27-
Name five natural oils used in paints.
Ans-
Linseed oil, castor oil, olive oil, tung oil, Soya oil and palm oil.
Q28- What does oleoresinous means? Ans-
A mixture of oil and resins.
Q29-
Name an inorganic high temperature service binder.
Ans-
Silicones, usually carbon or aluminium pigmented.
Q30- Name two pigments likely to be used for high temperature service. Ans-
Carbon and aluminium.
PAINT TECHNOLOGY (2)
(Wednesday)
Q01-
By what name would you call the basic unit of a polymer?
Ans-
Poly means many and Mers means single units, can be single atom or molecule.
Q02- What is polymerisation? Ans-
Joining together of a string structure of repeated units.
Q03- Name three types of polymers. Ans-
Linear polymer, branched polymer and cross linked polymer.
Q04-
What would be the characteristics of a short oil paint?
Ans-
Less than 45% oil to resin, fast drying, brittle
Q05-
What would be the characteristics of a long oil paint?
Ans-
More than 60% oil to resin, slow drying properties, elastic,
Q06-
What is meant by the term “opaque pigment”?
Ans-
Inert particle with excellent scattering properties in order to give covering power, opacity and colour,( Coloring pigment)
Q07-
What is the typical size of a pigment partical?
Ans-
1/10 micron. 0.1 Micron.
Q08-
Briefly describe the difference between “saturated” and “unsaturated” whe n referring to oils or
th
polymers. Ans-
Saturated oil will not solidify by polymerisation to form a film and unsaturated oil will combine with oxygen.
Q09-
Name two drying oils, which are unsaturated.
Ans-
Linseed oil, tung oil. Semi drying oil and Non drying oil.
Q10-
What is the main difference between a dye and a pigment?
Ans-
Dye can easily dissolve but pigment cannot.
Q11- What are the sources of pigments? Ans-
Animal, vegetable, mineral and synthetically produce.
Q12-
If Titanium Dioxide was used in paint, what would be the colour?
Ans-
White colour.
Q13-
Name three rust inhibitive pigment considered to be toxic.
Ans-
Red Lead, calcium plumbate, Coal tar and zinc chromate.
Q14- Name four commonly occurring minerals used as extender pigments.
Ans-
Kaolin, china clay, calcium plumbhate, magnesium silicate and aluminium silicate. (4.12)
Q15- Name three laminar pigments. Ans-
Micacous iron oxide, Glass flake, Graphite and Aluminium flake.
Q16- If pigment was added way below the CPVC, how would it affect the film? Ans-
A film have a good gloss properties but poor covering power and have tendency to blister or low cohesive strength.
Q17- The abbreviation CPVC means what? Ans-
Critical Pigment Volume Concentration.
Q18-
why are thixotropes added to a paint formulation?
Ans-
To give more shelf life and higher film thickness.
Q19- If carbon was used as a pigment what would be the paint colour? Ans-
A black colour.
Q20
Name four properties that a binder contributes to a paint film?
Ans-
Ease of application, adhesion to substrate, abrasion resistance, chemical resistance and cohesive strength.
Q21-
Describe how a basic inhibiter works?
Ans-
Added into primer to protect the steel substrate by passivation.
Q22- which of the common extenders could not be used in white and pestle? Ans-
Slate flavor.
Q23-
How could the film be affected if pigment was added above the CPVC?
Ans-
All particle are not wetted, the paint film would be porous, low in cohesive strength and adhesion.
Q24-
Which of the rust inhibitive pigment is the most common?
Ans-
Zinc phosphate.
Q25-
Why are the extenders used in paint formulation
Ans-
Provide adhesion, cohesion, films strength and durability.
Q26- If chromium was used as a pigment, what colour would the paint be? Ans-
Green, yellow and oranges.
Q27-
Why are plasticisers added to paint?
Ans-
To give paint flexibility and reduce brittleness.
Q28- Two metals are commonly used as galvanic pigmentation, name them. Ans-
Zinc and Aluminium.
Q29-
Why are driers added to oil based paint?
Ans-
For oxidizing oil and resin which are added during paint manufacturing.
Q30-
What is meant by the term ‘thixotropic’?
Ans-
It is a thickener which also allow a higher film thickness.
Q31-
What is meant by the term ‘aggregate’ when referring paint?
Ans-
Process of milling or grinding a paint ingredient to a suitable size.
Q32-
If an antioxidant was added to paint, what would it do?
Ans-
Its will retard the formation of skin on the paint surface.
Q33-
Give the names of two plasticisers.
Ans-
Castor oil and coconut oil. Alkyd resins and non drying oil.
Q34- What is meant by the term solution? Ans-
The resulting liquids I.e. salts mix with water will result salty water. Water and sugar are solution.
Q35- Give two example of a solution. Ans-
Binder and solvent, water and salt, water and sugar.
Q36-
What is meant by the term dispersion?
Ans-
No solubility between two materials e.g. Paint.
Q37-
There are two types of dispersion, what are they?
Ans-
Suspension and Emulsion.
Q38- If paint cures by chemical reaction is it reversible or convertible? Ans-
Convertible/Non Reversible.
Q39-
what types of polymerization occurs in chemically curing paint?
Ans-
Cross linked Polymer.
Q40-
Name a paint which dries solely by solvent evaporation.
Ans-
Chlorinated Rubber, Vinyl, Acrylic, cellulous material and lacquer.
Q41-
What is meant by ‘non convertible’?
Ans-
Allowing the polymer in a paint structure back into solution.
Q42-
What is meant by ‘non reversible’?
Ans-
Not allowing the polymer in a paint structure back into solution.
Q43- Name four drying mechanisms. Ans-
Solvent Evaporation, Oxidation, Chemical Curing and Coalescence.
Q44- In a coating, which dries by solvent evaporation, what type of polymerization occurs. Ans-
Chlorinated Rubber, Vinyl’s, Acrylic and fall into Linear Polymer categories.
Q45-
What is another term for Fineness off Grind?
Ans-
The Hegman Grind Gauge which used to measure degree of dispersion of paint.
Q46-
Which generic type of paint dry by solvent evaporation followed by oxidation.
Ans-
Alkyd, Phenolic and neutral oil and resin.
Q47-
What types of polymer forms during oxidation?
Ans-
Cross linking Polymer.
Q48-
What term applies to paint drying at ambient temperature?
Ans-
Air Drying. Reversible or non convertible and linear polymer.
Q49-
What is meant by the term ‘coalescence’?
Ans-
Physically joint together.
Q50-
What is meant by the term’ Pot-life’
Ans-
The periods of time after mixing which the paint must be used.
Q51-
Name three curing agents used in epoxies?
Ans-
Amides, Amines and Isocycnate.
Q52-
Is paint a solution or dispersion, qualify?
Ans-
Dispersion.
Q53- What is exothermic reaction? Ans-
Giving off heat, the container will warm up.
Q54-
What is meant by the term ’Induction period’?
Ans-
The length of time after mixing which the paint should stand before used to allow polymerization/ wetting of paint.
Q55-
What is the difference between ‘thermoplastic’ and thermosetting’?
Ans-
Thermosetting means the material will cure with the application of heat. And Thermoplastic means materials soften with the application of heat.
Q56-
With a chemically curing paint, what type of polymerisation occurs?
Ans-
Cross Linking Polymer.
Q57-
Two other terms relate to induction period, what are they?
Ans-
Stand Time and Lead Time.
Q58-
Does a Phenolic resin have an induction period?
Ans-
Yes, the time depends on Paint Manufacturer recommendation.
Q59-
Which of the following binders are reversible?
Ans-
a)Epoxy Alkyd
b) Phenolic f) Cellulose
c) Vinyl g) Urethane
d) Chlorinated Rubber, h) Silicon
Q60-
Is an epoxy powder paint thermoplastic or thermosetting?
Ans-
Thermosetting, the powder will cure with the application of heat.
e)
Q61-
If a coating is permeable, what does it mean?
Ans-
It’s a Barrier coat.
Q62-
What is meant by cross-linking, give two binders as an example?
Ans-
????????
Q63- What is opposite to exothermic? Ans-
Endothermic reaction, taking in heat, the paint container will cold and forming condensation.
Q64- What is the term used for paints needing temperatures in excess of 65°c to cure? Ans-
Stoving, using oven or infra red.
Q65- What would be a typical induction period for Chlorinated rubber paint? Ans-
Depends on Technical Data Sheet recommendation from paint manufacture.
Q66-
Name a material used as a dryer in paint formulation.
Ans-
Heavy metal salts, Octoates or naphtanes of cobalt, manganese and zirconium.
Q67-
Why would bentonite or wax be used in paint formulation?
Ans-
These are “Thixotropes” added to paint keep solid particulate constituents in depression within the paints.
Q68-
Name two materials used as plasticisers.
Ans-
Coconut oil And Caster oil / Alkyd and Non drying oil.
Q69-
What generic type of paints would use anti-oxidant?
AnsQ70- How does a single pack? Epoxy Easter paint dry. Ans-
By oxidizing.
Q71- How is Dew-point defined? Ans-
The temperature at which water vapor in the air will condense.
Q72-
How is relative humidity defined?
Ans-
The amount of water vapor in the air expressed as a percentage of the amount of water vapor which could be in the air at that same temperature.
Q73- When using a whirling hygrometer which bulb should be read first and why? Ans-
Always wet bulb first and immediately, when rotation stops wet bulb start rise in temperature.
Q74-
At what speed should be thermometer bulb pass through the air?
Ans-
At a speed of 4meter/second.
Q75- What should be used when wetting the wick on whirling hygrometer? Ans-
Distilled water.
Q76-
By what other name can we refer to a whirling hygrometer?
Ans-
Aspirated Hygrometer and Psychrometer.
Q77-
When the air temperature rises does the air’s capacity to hold water increase or decrease?
Ans-
Decrease.
Q78- What is the stated criterion for accept, prior to calculation, on a whirling hygrometer? Ans-
Must be according to BS 2482.
Q79-
Name two pieces of equipment used for taking steel temperature?
Ans-
Limpet Gauge, Digital Thermometer, Thermocouple and Touch Pyrometer.
Q80- Is it possible for wet bulb temperature to be higher than the dry bulb? Ans-
No, its impossible.
PAINT TESTING
(Thursday) Q01- Define viscosity. Ans-
Fluids resistance to flow, where the liquids with a high viscosity is one which a high resistance to flow and it would not run easily, a low viscosity is fluids runs very easily.
Q02- What is meant by high viscosity? Ans-
Liquids with a high resistance to flow. And would not run easily.
Q03-
Approximately, what is the viscosity of water?
Ans-
One centi poise.
Q04-
Name the CGS and SI units of dynamic viscisity?
Ans-
CGS-Poise and SI-Newton per square meter.
Q05- Name three different flow cups. Ans-
Ford Flow Cup, Zhan and Frikmar, and DIN.
Q06-
When using a flow cup which unit of viscosity would be used?
Ans-
SI unit, Time in second at the measure temperature (second/20°C±0.5)
Q07-
In ‘Ford flow cup No.4’ what does ‘4’ relate to?
Ans-
Diameter of nozzle opening at the bottom of cup.
Q08- Give the name of three different rotational viscometers. Ans-
Rotothinner-Dynamic Viscosity and Kreb stormer Viiscometer-Kinematics Viscosity.
Q09-
Give a reason for performing a viscosity test on site.
Ans-
To find out the addition of thinner. Comparing the sample taken from the operator at the point of application and the sample from the paint manufacture techni cal data sheet.
Q10-
Which viscometer would not be used on thixotropic paint?
Ans-
Ford Flow Cup.
Q11- Why is temperature very important when doing viscosity test? Ans-
Temperature would affect the drying and curing of paint under test.
Q12-
What is the main difference between the rotathinner and Krebs Stomer?
Ans-
Rotothinner giving dynamic viscosity and Krebs Stomer giving kinematics viscosity.
Q13-
Describe how to use a Ford Flow Cup.
Ans-
Clean and dry the cup, put on the triangular stand and make it parallel using spirit bubble leveling on the lid of cup, open a cup, place a finger at a nozzle under a cup, fill a cup with a paint under test and clean out any accesses if paint by ruler, standby with stop watch, at the time we remove our finger from nozzle immediately at the same time press start button at stop watch and look at the first brake of paint which drop from nozzle under cup and stop the stop watch. The reading should be Second/20°C±0.5.
Q14-
Give another name for a Fineness of grind gauge.
Ans-
The Hegman Grind Gauge.
Q15-
Is low flash point safer than a high flash point?
Ans-
NO, the higher Flash point is better and safer.
Q16-
How and for what a Hegman grind gauge used?
Ans-
Its used to measure the degree of dispersion of paint, Paint is added to the deepest point of the scale and drawn to totally fill the groove by a special scraper bar, then check the 3mm band where aggregates through the surface of paint.
Q17- Briefly describe how to do the volatile, non volatile test to BS3900 Pt B2 Ans-
10.1 page
Q18-
Name the equipment used to determine the flash point of a solvent?
Ans-
Able Cup.
Q19-
What colour should the flame be at the flash point?
Ans-
Blue flame flash.
Q20- What formula is used to calculate the density? Ans-
Density=Wt ÷ Volume
Q21-
What formula is used to calculate the specific gravity?
Ans-
SD or SG=Density of X ÷ Density of water.
Q22- What is the relative density? Ans-
Density of Water. Specific gravity
Q23-
What are the other names for a density cup?
Ans-
Relative Density Cup, Specific Gravity Cup, Weight per liter Cup, Weight per gallon Cup and Pyknometer.
Q24- What is the stoke, the unit for?
Ans-
Kinematics Viscosity.
Q25-
Which test is used to determine Abrasion Resistance?
Ans-
Taber Rotary Abraser.
Q26-
Which equipment would be used to determine flexibility?
Ans-
Conical Mandrels.
Q27- Which equipment would be used to measure impact resistance? Ans-
Tubular Impact Tester.
Q28-
For what reason would the Koenig Albert Apparatus be used?
Ans-
Test the hardness of paint after fully cured.
Q29-
For which two reasons could a density cup be used on site?
Ans-
Determine correct mixing ratio and correct percentage of thinner added into a paint.
To calculate density if 2 pack material has been used.
Q30- Name four accelerated test boxes. Ans-
Humidity Cabinet, Salt Spray Cabinet, Water Soak Test, Temperature Cycling and prohesion test.
Q31- Why a tropical box would be used? Ans-
Testing a pain in a situation of tropical condition.
Q32-
would a paint be higher or lower density than water?
Ans-
Higher than density of water. ( Yes)
Q33- How would the density be affected if solvent was added to paint? Ans-
Solvent would dilute the paint.
Q34-
What is the capacity of a density cup?
Ans-
100cc.
Q35-
What is the difference between SG and Density?
Ans-
SG= Density of paint ÷ Density of water Density = weight ÷ Volume
Q36-
What information could be obtained from a water soak test?
Ans-
Water absorption.
Q37- What information could be obtained from a temperature cycling test? Ans-
Subject to constant cycle temperature from hot to cold and hot again.
Q38-
What information could be obtained from a cold check test?
Ans-
Constant expansion and contraction which can result in a crack.
Q39- Name four drying and curing test?
Ans-
Ballotini Test and BK Drying Time Recorder.
Q40- What stage of the BK test would be recorded as the drying time? Ans-
When there are no any scratches visible on a paint surface.
Q41- Name three methods of determining opacity? Ans-
Black and white fused plate, Through Type and Hiding Power Chart and
micrometer adjustable
film applicator. Q42-
What affects the opacity of a paint film.
Ans-
Capability of paint to giving hiding power to the underlying surface.
Q43-
Why would Pfund crypto meter be used.
Ans-
To checked opacity of paint.
Q44-
Give one reason why an inspector is would use a PIG gauge?
Ans-
To determine the individual thickness of paint film.
Q45-
Why are wet paint film thicknesses needed?
Ans-
To control thickness during application which give a confidence that after paint dry the thickness still in the range of dry film thickness a per spec requirement and control a paint consumption.
Q46-
Name two method of measuring WFTs.
Ans-
Eccentrics Rims and Wet Combs.
Q47-
What is the reason for taking WFT immediately after application?
Ans-
To determine accurate thickness reading.
Q48- Where could an inspector find information to determine if a 2 pack paint was mixed in the correct proportions, using a density cup? Ans-
Comparing with paint manufacturer technical data sheet.
Q49-
Can a banana gauge be used on non-ferromagnetic substrate?
Ans-
No, it can be used on ferrous metal substrate only.
Q50- Could an eddy-current gauge be used on ferromagnetic substrate? Ans-
No, It can be used on non ferrous metal substrate only.
Q51- Can a horseshoe gauge be used on non-ferromagnetic substrate? Ans-
No, it can be used on ferrous metal substrate only.
Q52-
A part of which test would a bar applicator be used?
Ans-
Hiding power chart in opacity test.
Q53- Which instruments would be used to measure reflectivity? Ans-
Glossmeter.
Q54- How does a glass meter work?
Ans-
By a reflectance of light at specified angle.
Q55-
Which factors in paint govern the degree of gloss?
Ans-
Degree of dispersion, particle size, resin type, solvent type and pigment volume concentration.
Q56- In a primer / mid coat what would be the expected degree of grind? Ans-
40µ m.
Q57-
In gloss paint what would be a typical degree of grind?
Ans-
10 - 20µm.
Q58- What percent reading would be expected when measuring gloss on a glass panel? Ans
Almost 100%.
Q59-
Using a gloss meter a reading of 25% would signify what?
Ans-
Degree of gloss for primer and mid coat paint.
Q60- If an aggregate size of 35µm was present in a paint of 30 µm DFT what would be likely result when using a gloss meter? Ans-
Light would be deflected and the gloss percentage reading would be lower.
Q61- Name common tests for determining adhesion of paint film? Ans-
V-Cut test, Cross Hatch Cut and Dolly test.
Q62- Which adhesion tests are quantitative? Ans-
Dolly Test units in Mpa/psi/lb/Newton.
Q63- Inter coat adhesion and primer to substrate adhesion are two adhesion fault name the third? Ans-
Cohesive failure within a paint film.
Q64- What chemical solution is used to conduct a Cathodic disbondment test? Ans-
Sodium Chlorides.
Q65-
Which gas involved at the cathode causes disbondment?
Ans-
Hydrogen and Chlorine gas.
Q66- What criterion is used when assessing a Cathodic Disbondment test panel? Ans-
After V-Cut the paint must not exposed the substrate. I.e. F.B.E 5mm only after 28 day.
Q67-
Name the two methods of applying Cathodic protection?
Ans-
Sacrificial Anodes and Impress Current.
Q68-
What is used to determine the potential of a pipeline?
Ans-
??????????
Q69-
Would it be advisable to refill a pipe trench with carbonaceous backfill?
Ans-
??????????
Q70-
Does a Cathodic protection system eliminate corrosion?
Ans-
No, these systems only control the corrosion formation.
Q71-
Can the external surface of a tank be protected?
Ans-
Yes, by primary defence (coating)
Q73- What voltage would be used on a 250 um thick paint using a sponge type pinhole detector? Ans-
Setting at 9volts.
Q74- What voltage would be used on a 450 um thick coating wiyh a sponge type pinhole detector? Ans-
Setting at 67.5volts or 90volts.
Q75- When using wet sponge, what other liquid is added to the water? Ans-
Detergent or washing liquids.
Q76- In wet sponge holiday testing what function does the additive perform? Ans-
To allow immediate penetration of the water and providing a very low resistance circuit back to the control box.
Q77- Would it be advisable to do wet sponge detection on galvanizing? Ans- No, On galvanized surface holiday detection can’t be performed. Q78-
why work upwards on a vertical surface with a wet sponge?
Ans-
To wet out the entire surface.
Q79-
Does a sponge detector work on AC or DC current?
Ans-
Its work on DC current.
Q80- Other than the wet sponge, which other equipment could be used to determine the presence of pinholes / holidays? Ans-
The high voltage Holiday Detector.
Revision Question General (Friday)
Q01- Name two categories of paint mill. AnsQ02-
What is the main reason to processing paint in a mill.
AnsQ03-
Briefly describe how ball mill works?
AnsQ04-
Briefly describe how attritor mill works?
AnsQ05-
When would steel balls not be used in ball mill?
AnsQ06-
A bead mill is some times called by which other name?
AnsQ07- How does a colloid mill work? AnsQ08- Name eight items of information listed on a material data sheet? AnsQ09-
What do you understand from the term “Halogenated h ydrocarbon”?
AnsQ10- How can we determine the viscosity of high viscosity paint? AnsQ11-
Briefly describe the principle of CP?
AnsQ12-
What function does a primer have in paint system?
AnsQ13-
In a mordant primer what is the main working constituent?
AnsQ14- What advantages does electrostatic application method provide? AnsQ15-
Which is the most expensive type of brush filling?
AnsQ16Ans-
What is cohesive failure in paint, give the main cause?
Q17-
Why does a zinc rich paint need a strong binder?
AnsQ18-
Why are etch primers not spray applied?
AnsQ19-
What do you under stand by the term over spray?
AnsQ20-
Name four method of determining DFTs?
AnsQ21- What is a psychrometer used for? AnsQ22-
What colour should a galvanized surface be after application of “T” wash?
AnsQ23-
How soon can a “T” washed substrate should be coated?
AnsQ24- Other than pigment, base and curing agent name two other constituent of FBE powder paints? AnsQ25- Give the main difference between airless and conventional spray? AnsQ26- Brush application has advantages over spray application, what are they? AnsQ27- What is the main consideration when selecting a metallic pigment for sacrificial paint? AnsQ28- What is meant by Shererdizing? AnsQ29-
Name three types of paint feed for conventional spray?
AnsQ30- What is the Colorizing process? AnsQ31-
Why would a sealer be applied to aluminum metal spray?
AnsQ32-
What is the BS 2015 term for skipped or missed area?
AnsQ33-
A colour has three properties, what are they?
AnsQ34-
Why would paint be applied by hot spray?
AnsQ35-
On an airless spray tip how blockage cleared?
AnsQ36-
How atomization is achieved using conventional spray?
AnsQ37-
How atomization is achieved using airless spray?
AnsQ38- What is dip coating? AnsQ39-
What do you under from the term Roppiness?
AnsQ40-
What is efflorescence and how does it occur?
AnsQ41-
Name two of melting aluminum to enable it to spray?
AnsQ42- What is flocculation? AnsQ43-
What could be the cause of bittines in a paint film?
AnsQ44-
What is a Tie coat?
AnsQ45-
How many depressions of the bellows are needed for the drager test?
AnsQ46- What are the hazard signs are Toxic, Very Toxic, Harmful, and corrosive? AnsQ47- What is saponification? AnsQ48-
What unit is used for measuring toxicity?
AnsQ49- Which material would have to used on a perpetually damp surface? AnsQ50-
What is pudding?
AnsQ51- What air inlet pressure is needed to give 2500 psi delivery with 35:1 pump? Ans-
Q52-
What cause lifting of a paint film?
AnsQ53-
What is cissing and how is it caused?
AnsQ54- What is mean by abbreviations: OES, OEL, MEL, UEL, LEL and RAQ? AnsQ55- Why would a painting inspector use potassium hexacyonoferrate? AnsQ56-
What would be an average thickness for galvanizing?
AnsQ57- How can you tell the difference between blooming and chalking? AnsQ58-
What could be the reason for inter coat adhesive failure?
AnsQ59- How could you determine quality of added thinner in thixotropic paint? AnsQ60- Why are manufacturers developing solvent free, water born and powder? AnsQ61-
What would be the cause of grinning on a paint film?
AnsQ62-
How can “Bleeding “ be avoided?
AnsQ63-
In less than 30 words, Explain the duties of painting inspector.
Q64- Name five documents, which a painting inspector might need on a contract?
Q65-
What information should be given on daily report sheet?
Q66-
Curtains, sags, Runs and Tears are a result of what.
Ans-
Q67- Some binders can be modified to use water as solvent, name four.
Q68-
What is meant by term “Strip coat”?
Ans-
Q69-
How many cm³ are there in 4.5 Liters?
Ans-
Q70- A paint data sheet provides a wealth of information, name eight.
Revision Question PA 10 Specific
Q01- what is the specified course of action for grit inclusion? AnsQ02-
The term ‘Long term’ refer to what?
AnsQ03- What is the difference between new and weathered galvanizing? Ans-
Q04-
what criterion determines which paint system should be used?
Ans-
Q05-
What is the total DFT of the compliant epoxy system?
AnsQ06-
What is the total DFT of the water born system?
AnsQ07-
when can ladder and other means of access be removed?
AnsQ08- Two materials are specified to use on damp surface, what are they? AnsQ09-
After removal of a non- drying paint, which type of primer is recommended?
AnsQ10-
Some none ferrous substrates are painted for aesthetics only, name four.
Ans-
Q11- which three non-ferrous substrates are painted for anti corrosion purposes? AnsQ12-
According to PA 10 in which situations would ‘T’ wash be used?
Ans-
Q13-
How many coats of primer are specified on surface at 100 – 149 ° C.?
AnsQ14- Give preferential order of coating system for surfaces 150 – 340 ° C. Ans-
Q15-
Is it mandatory for a contractor to produce a test area?
Ans-
Q16-
List four items needing masking off prior to blasting and painting.
Ans-
Q17-
Which Aluminium substrate would not be sweep blasted?
AnsQ18- Which three paint systems are specified for use on Aluminium? Ans-
Q19- What differences are there in new and maintenance painting specifications for substrates bolw 100 °C.?
Ans-
Q20- Toxic coatings need special considerations for removal from substrates, name two methods which comply. Ans-
Q21-
In which situations is a permit to work required?
AnsQ22- Which primers are specified for non-weathered galvanizing? AnsQ23-
Which primers are specified for weathered galvanizing?
AnsQ24-
According to PA 10, is flame cleaning allowed?
AnsQ25-
According to PA 10, is thinning of paint allowed?
AnsQ26- What temperature range is covered by ‘hot duty service? AnsQ27-
Does PA 10 cover internal coating on pipes?
AnsQ28Ans-
What is the specified overlap on repair areas?
Q29- What would be the specified surface preparation and coating system for Aluminium cladding? AnsQ30-
What would be the procedure for removal of algae and mould?
AnsQ31- What would be the procedure for degreasing prior to surface preparation? Ans-
Q32- What would be the procedure for degreasing after to surface preparation? Ans-
Q33-
When blast cleaning on an AGI what precautions are taken?
Ans-
Q34-
Is it permissible to prepare paint by stirring?
AnsQ35- What would be surface preparation method for new galvanizing? Ans-
Q36- When would it be necessary to apply a sealer to inorganic zinc silicate? Ans-
Q37- How could areas of a paint breakdown be prepared for repainting? Ans-
Q38-
What information should be on a paint can label for BG?
Ans-
Q39- When measuring DFTs over galvanizing what allowance are made? Ans-
Q40- What id the first firsts coat applied to galvanized substrates and why? Ans
