Bgas test 1.doc

BGAS-CSWIP PAINTING INSPECTOR Grade 3/2 Name I/D No. Exam date

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Answer all Question

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Name the three factors needed for corrosion to occur. Anodes, Cathodes and Electrolyte.

What is a Corrosion? Degradation of metal by chemical or electro chemical mean.

In which environment are you likely to encaunter Chlorides Salts? Marine and damp

What is Millscale, and when and where does it occur? Combination of Oxides on the

metal surface during rolling process of metal. ( Wusetite,Hematit e and Megnatite )

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Name three factors which accelerate corrosion reaction. Temprature, Hygroscopic Salts, Aerobic condition.

Why is it important to have good surface preparation? For a better adhesion of paint to the substrate.

Give three different names for the cross section of a blast. Blast Profile, Anchor Pattern, Amplitude and Peak to through height.

What would be considered to be an idel shot and grit mix? 20-30% of Grit to 70-80% Shot

What is the purpose of mixing shot and grit?

For creat more uniform profile where Grit cut the profile and Shot control the peak to through height.

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If cracks or lamination are found on a substrate after blasting, what steps should be taken? Refer to the Engineer for UT and his decretion, or grind off that areas,welding by buttering or padding technique,grinds smooth and reblast again on that areas. page 01

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Name the gauge for measuring pressure at the blast nozzle. Hypodermic Needle Gauge. Insert the needle through the hoses near the blast nozzle, at approximately 45 degree angle with the needle facing towards to the blast nozzle. What is meants by

the terms of "Burnishing"? Polishing and smooth shiny area & does not provide good adhesion for a paints.

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What is the Footner Duplex Process of surface preparation? Pasivation process after Pickling process complete. What is meant by " St 2 and St 3"? Standards for hand and power tool cleaning or degree of cleanliness, St 2 means Thorough hand and power tool cleaning, and St 3 means Very thorough hand and power tool cleaning. What is a "Deadman Handle"? Blasting triggers,which always under operator control. Describe the "Footner Duplex Process". After Pickling, immersed the material into a bath of Phosphoric or Chromic acid

solution for one to two minute with iron filling.Rinse in clean water and check for pH value, and the reading should be in the range of pH4.5 to pH7.0.This process are to passivate the substrate.

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Why is the Phosphating or Chromating of steel done? To forms a rust inhibitive layers, which passivate the surface and increase the adhesion properties and also extremly resistance to cathodic disbondment. How many photographs of Blast Cleaning standards are shown in BS 7079 Pt A? Total 14 photographs, which 2 photo for cleaning rust grade A, and 4 photo for cleaning on each rust grade B,C and D. Would it be good practice to apply

Chlorinated Rubber over Alkyd resin paints? No,Chlorinated Rubber using a strong solvent and Alkyd using a weak solvent.If painted over, strong solvent will disolve a weak solvent and can causes of wrinkling or lifting. 20-

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What is meant by "Opaque"? Innert particles with excellent light scattering properties in order to give covering power, opacity and colour. How does paint using the barrier principle works? Forms a thick immpremable layer of high electrical resistance, applied over primer coat to prevent further water passing into the film and leaching out the inhibitive pigmentation. How does paint using the passivation principle works? By a chemical reaction between

the paint constituents and the substrate.

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Name six properties of Binder. Ease of application, adhesion to substrate, abrasion resistance, chemical resistance, cohesive strength, ability to resist the passage of water. What would be the characteristic of a long oil paint? More than 60% oil to resin, elastic and slow dry. Why are Thixotropes added to a paint formulation? For paint to keep solid particulate constituents in despersion within the paint and stop settlement and provide thickening effect. Describe how a basic inhibitor

work. Added into a primer to protect the steel substrate by passivation. 27-

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Why a plasticisers added to paint? To give paints a flexibility and reduce brittlenes. Name four drying mechanisms. Solvent evaporation, oxidation, chemical curing and coalescence. What is another term for Finess of Grind? The degree of dispersion of paint. What is meant by the term " Pot Life "? The period of time after paint mixing which the paint must be used. What is an Exothermic reaction? Giving off heat, the container will warm up. What is meant by the term "Induction period "? The length of time

after mixing which the paint should stand before used. 33-

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How is Dew Point defined? The temprature at which water vapour in the air will condense. How is Relative Humidity defined? The amount of water vapour in the air expressed as a percentage of the amount of water vapour which could be in the air at that same temprature. What is a Viscosity? A fluid resistance to flow. Which viscometer would not be used on thixotropic paint? Ford Flow Cup No. 4

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Name four accelerated test boxes.

Humidity cabinet, Salt spray cabinet, water soak test, temprature cycling and prohesion test.

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What information could be obtained from a tempreture cycling test? Subject to constant temprature cycle from hot to cold. What is the reason for taking WFT immedietly after application? To determine accurate reading because if the WFT taken after a few minute the solvent already evaporate away and paint film start their curing or drying. Name three common tests for determaining adhesion of a paint film? V-Cut test, Cross Hatch Cut test and Dolly Pull-Off test. Name eight items of information listed on a Product data sheet. Volume solids %, Flash point, Potlife, Dry to touch, Mixing

solvent, specific gravity, Wet film thickness, Dry film thickness, nozzle spray tip size.

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What function does a primer have in a paint system? As a passivating layer, wet out the substrate and provides excellent adhesion and provide key for any subsequent layer. Give the main differences between Airless and Conventional spray. Application range, productivity and efficiency. In not less than 30 words, explain the duties of a Painting Inspector. Duty of Painting Inspector are, measuring, examining, testing, gauging one or more charateristic of a product or service and comparing these with specified requirements to determine conformity. i.e: Visual inspect paint finish,

measure and report wet,dry bulb, dew point and relative humidity.Control storage of paint and abrasives.Check surface condition before and after surface preparation.Recor d weather condition and compliance with specification. Measure surface profile,DFT,WFT,p ot life and induction periods. Report any NonConformance to Engineer.Check operation of blasting and painting. Carried out quality test and compliance with specification.

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Name five documents,which a Painting Inspector might need on contract. Job specification, procedure, project drawing, technical data sheet, quality plans, code of practice. What is meant by the term of Stripe Coat?

An extra coat applied on areas of difficult accesses such as bolt and nuts, edges, angle and pipe flanges with a gurantee of minimum DFT in the system.

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Properties and Performance of paint are covered in which B.G specification? BGC PS PA 9. What are the considerations when selecting a paint system? Function, substrate, environment, special constrain, cost and maintainance.

What should be the substrate reaction when T-Wash is applied to a newly galvanised? The reaction between T-Wash and newly galvanised was the substrate turn into a black surface.

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What Volume of paint would required to cover an areas of 300 square meters, to a specified DFT of 65 micron, using a paint of 45% volume solid? 43.35% -

45 (vs) X 10

65 (DFT) 300(m2) ÷ 6.92m2/ltr(tsr) = 43.35ltr

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= 6.92m2/ltr (theorytical sperading rate)