This set of Corrosion Engineering Multiple Choice Questions & Answers (MCQs) focuses on “ Environments – Atmospheric Corrosion”.
1. Which of the following is/are the classifications of atmospheres regarding atmospheric corrosion?
a) Industrial
b) Marine
c) Rural
d) Industrial, marine and rural
View Answer
Explanation: Atmospheric corrosion can be defined as the corrosion of metals in surrounding corrosive environment. It can be classified into three types namely industrial, marine and rural atmospheres.
2. Which of the following is/are the primary causes of atmospheric corrosion?
a) Moisture
b) Oxygen
c) Moisture, oxygen and sulfur contaminants
d) Sulfur contaminants only
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Explanation: The primary causes of atmospheric corrosion is moisture, oxygen and sulfur contaminants. Absence of either moisture or oxygen in at least form will result in no corrosion.
3. Corrosion of steel on the seacoast is 400 to 500 times is more corrosive than in a desert area.
a) True
b) False
View Answer
Explanation: Corrosion of steel on the seacoast is 400 to 500 times is more corrosive than in a desert area. This due to the contamination of atmosphere with sodium chloride and other impurities at the seacoast.
4. How many times that industrial corrosion is more corrosive than rural atmospheres?
a) 10 to 20
b) 50 to 100
c) 30 to 50
d) 100 to 150
View Answer
Explanation: Industrial corrosion is 50 to 100 times more corrosive than desert areas. It is due to the presence of Sulphur burned gases such as SO2, SO3 and these results in the formation of sulfurous and sulfuric acids in the presence of moisture.
5. Which of the following is/are the reasons for more corrosiveness of industrial atmosphere than rural atmosphere?
a) Formation of sulfurous and sulfuric acid
b) Ejection of corrosive ammoniacal solutions
c) Formation of sulfurous and sulfuric acid and ejection of corrosive ammoniacal solutions
d) High levels of carbon dioxide
View Answer
Explanation: Formation of sulfurous and sulfuric acid from sulfur burning gases and ejection of corrosive ammoniacal solutions are the reasons of industrial corrosion. Whereas carbon dioxide is not corrosive in nature.
6. Which of the following alloying elements increase resistance of steel to atmospheric corrosion?
a) Copper
b) Nickel
c) Chromium
d) Copper, nickel and chromium
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Explanation: Steel is the most widely used metal for various metallic structures in all atmospheres. The resistance of steel can be improved by alloying elements such as copper, nickel and chromium. This is due to formation of stable, thick and adherent protective film.
7. Which of the following metals are widely used for atmospheric applications?
a) Copper and lead
b) Copper, lead, aluminum and galvanized steel
c) Galvanized steel only
d) Galvanized steel and copper
View Answer
Explanation: Copper, lead, aluminum and galvanized steel are widely used for atmospheric corrosion applications. Improving the corrosion resistance of steel with small alloy additions is now commonly used along with weight-saving applications.
8. Which of the following alloys is also called as weathering steels?
a) Low-alloy steels used for atmospheric applications
b) High-alloy steels used for atmospheric applications
c) Low-alloy copper alloys
d) Low-alloy aluminum alloys
View Answer
Explanation: Low-alloy steels used for atmospheric applications is also known as weathering steels. It is also used in weight-saving applications and to increase durability of paint coatings.
9. Sheltered corrosion is the type of corrosion where moisture condenses or accumulates and does not dry out for long periods of time.
a) False
b) True
View Answer
Explanation: Sheltered corrosion is the type of corrosion where moisture condenses or accumulates and does not dry out for long periods of time. Corrosion on inside of an automobile door and inside of a partially filled automobile gasoline tank are the examples of sheltered corrosion.
10. Which of the following phenomenon that results in rapid corrosion on the inside of large storage tanks occurs when moisture-laden salt air is drawn in?
a) Sheltering
b) Breathing
c) Exhalation
d) Crevice
View Answer
Explanation: Breathing results in rapid corrosion on the inside of large storage tanks occurs when moisture-laden salt air is drawn in. This can be prevented by protective coatings for steels and blanketing with nitrogen or dry air inside the tank.
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