Corrosion Ap Essay Questions And Answers

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REVISION QUESTIONS
Corrosion OP

- Monday

Is the electrical circuit in a corrosion reaction AC or DC?
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Does corrosion occur at the cathode or at the anode?
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Name the three factors needed for corrosion to occur.
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What is meant by the term electrolyte?
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What is corrosion?
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In the corrosion circuit do electrons flow from anode to cathode?
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Which gas is released at the cathode when the electrolyte is water?
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Which is the more noble metal, steel or Aluminium?
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Which is more electronegative, steel or Aluminium?
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10 If steel and copper were in contact in an electrolyte which would corrode?
11 Name two common Hygroscopic salts.
12 Name three metals used as sacrificial anodes on a steel pipeline.
13 What is the
approximate thickness of millscale?
14 Which of the two metals would corrode if steel and zinc were coupled?
15 Which other names relate to the Galvanic List?
16 In which environment are you likely to encounter chloride salts?
17 Which three compounds together form millscale?
18 If magnesium was coupled with zinc, which would corrode?
19 In which environment would sulphate salts be found?
20 What is an osmotic blister?
21 What is an ion?
22 What is meant by polaris~tion?
23 Is an anode positive or negative?
24 Can corrosion occur without an electrolyte?
25 Name a sub atomic particle.
26 What is millscale and when and where does it occur?
27 Name three factors, which can accelerate corrosion reactions.
28 Why is it considered essential to remove millscale prior to painting?
29 Why does an un-coated steel plate corrode?
30 If corrosion occurs at anodic areas, why does steel corrode evenly all over the surface?

Painting Inspection Grade 3,2. Rev I April 2004
Revision Questions
23.1
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~fATERIALS

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-Monday

Which British standard would be used in detennining the size of copper slag abrasive?
Which British standard would be used in detennining the size of metallic abrasives?
Which regulations prohibit the use of sand for blasting steel?
What is meant by the tenn 'key'?
Why is it important to have good surface preparation?
What is meant by the tenn sliver?
What is a hackle?
Name two other tenns that could be used for 'anchor pattern'?
What are the main advantages of using 'Testex papers' for measuring profiles?
What is meant by the tenn grade. relating to a blast finish?
What are the main factors governing the grade of a blast finish?
Can the grade of a blast fmish be detennined by using the surface comparators to BS 7079
Pt C3?
What profile range can be measured using X coarse Testex?
What profile range can be measured using coarse grade Testex?
What are the two theories of adhesion?
Briefly describe the mechanisms of the two theories of adhesion.
How many microns are in 1thou?
Give three different names for the cross section of a blast.
What is the approximate speed of abrasives leaving a venturi nozzle?
What is the most common cause of flash rusting on a blasted substrate?
What would be considered to be an ideal shot grit
mix?
What is the purpose of mixing shot and grit?
Which abrasive would have the effect of work hardening a substrate?
Name three methods of measuring or assessing a profile.
What is the most common cause of rogue peaks on a substrate?
In what situation would it be better to use steel grit in preference to copper slag abrasives?
If cracks or laminations are found on a substrate after blasting what steps should be taken?
Using comparators to ISO 8503, what are the three main profile assessments?
What are the other two assessments when the above three are not appropriate?
What would be size of copper slag needed to give a protile of 50 to 75 urn?

Painting Inspection Grade 3/2. Rev I April 2004
Revision Questions
23.2
Copyright @ 2003, TWr Ltd

TWI

rTTl.

'L/Lli

WORLD CEMRE FOR

MATERIALS
JOINING
TECH/IoOLOGY

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- Tuesday

What is the title of the BS 7079?
What are the four characteristics of an abrasive?
Why are blast hoses carbon impregnated?
Name the gauge used for measuring pressure at the blast nozzle?
Name four advantages of centrifugal blasting over open blasting.
According to BS 7079 is it possible to blast clean to an A Sal?
Is there any difference between an A Sal and B Sa1?
Could you tell the difference between rust grades A and B blasted to Sa3?
Could you tell the difference between rust grades C and D blasted to SaJ?
What would be a typical speed of abrasives leaving a wheel abrator?
What is considered to be the most efficient blasting pressure?
What is meant by the term "burnishing"?
What would be the equivalent to sa in the Sa grades?
What is the neutral figure on the pH scale?
How is pH measured?
Why are inhibitors sometimes added to water in wet blasting?
Name two typical areas where needle guns might be used?
What is the Duplex Process of surface preparation?
Which pH range covers acids?
Which pH range covers alkalies?
What is the meaning of pH?
Name three disadvantages of wet blasting.
Name two areas on a structure where flame cleaning cannot be done.
Which three basic operations are performed during flame cleaning?
How does BS 7079 define Flame Cleaning standards?
What is a 'lasons Hammer'?
What is meant by St2 and 8t3?
Two alloys are used to render wire brushes spark tree, what are they?
Why should 'Burnishing' be avoided?
Name two major disadvantages of using a needle gun.
After phosphating, what would be a typical pH requirement prior to coating?
What is understood by the term 'knock out pot'?
If an operator was blasting with a nozzle pressure of 80 psi. What would be his approximate efficiency?
Which solvents are commonly used for degreasing?
What is a 'dead mans handle'?
Why is carbon impregnated into blast hoses?
How is abrasive cleansed in a wheel abrator system?
What is the main disadvantage of high pressure jetting compared to other systems?
Name five methods of wet blasting.
What would be the typical temperature and concentration of 8ulphuric Acid in the pickling process? Describe the 'Duplex Process'.
What would be a maximum pressure for high pressure water jetting?
What are the disadvantages of wet blasting over dry blasting?
Describe the phosphating process.

Painting lnsp~ction Grade 3/2. Rev 1 April 2004
Revision Questions
23.3
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