Question 1

_______ is the primary alloying agent that affects resistance to oxidation.
A) Chromium
B) Molybdenum
C) Silicon
D) Aluminum

Accepted Answer

Chromium is the primary alloying agent that affects resistance to oxidation. It forms a protective oxide layer on the surface of the metal, which protects against further oxidation.

Question 2

To prevent carburization, select alloys with a strong surface oxide or sulfide film former such as ________.
A) Silicon
B) Molybdenum
C) Aluminum
D) Both A and C

Accepted Answer

Both silicon and aluminum are strong surface oxide formers and can help prevent carburization. Molybdenum is a good sulfide former but not as effective at forming strong surface oxide films. Therefore, the best choice(s) are A and C.

Question 3

_________ is surface initiated cracks caused by environmental cracking of 300 Series SS and some nickel based alloys under the combined action of tensile stress, temperature and an aqueous chloride environment. The presence of dissolved oxygen increases the propensity for cracking.
A) SSC
B) SOHIC
C) Cl SCC
D) HIC

Accepted Answer

The description matches Chloride Stress Corrosion Cracking (Cl SCC) which is a common form of environmental cracking in 300 Series SS and some nickel based alloys. The presence of an aqueous chloride environment, tensile stress, and temperature are the key factors that lead to Cl SCC. Dissolved oxygen further increases the propensity for cracking. Therefore, option C is the correct answer. The other options SSC (Sulfide Stress Cracking), SOHIC (Stress-Oriented Hydrogen-Induced Cracking), and HIC (Hydrogen-Induced Cracking) are different types of cracking that have different causes and mechanisms compared to Cl SCC.

Question 4

With cooling water corrosion, _________ oxygen content tends to ________ carbon steel corrosion rates.
A) Increasing, increasing
B) Decreasing, decreasing
C) Decreasing, increasing
D) Increasing, decreasing

Accepted Answer

Increasing oxygen content in cooling water typically increases the corrosion rates of carbon steel due to the enhanced electrochemical reactions that occur in the presence of oxygen.

Question 5

Although cracks may be seen visually, crack detection for caustic stress corrosion cracking is best detected by WFMT, EC, RT and ______.
A) PT
B) MT
C) ACFM
D) All of the above

Accepted Answer

ACFM (Alternating Current Field Measurement) is a non-destructive testing method effective for detecting surface-breaking cracks, including those caused by caustic stress corrosion cracking.

Question 6

_________ is accelerated high temperature wastage of materials that occurs when contaminants in the fuel form deposits and melt on the metal surfaces.
A) Spheroidization
B) Dealloying
C) Fuel ash corrosion
D) None of the above

Accepted Answer

Fuel ash corrosion is the accelerated high temperature wastage of materials due to the presence of contaminants in the fuel that form deposits and melt on metal surfaces. Spheroidization is a process of forming spherical metal particles, while dealloying is the selective removal of one or more components from an alloy. Therefore, neither spheroidization nor dealloying is related to the given definition.

Question 7

Major factors affecting sulfidation are alloy composition, temperature and ________.
A) Time
B) Stress
C) Concentration of hydrogen
D) Concentration of sulfur

Accepted Answer

The answer of Major factors affecting sulfidation are alloy composition,...

Question 8

300 Series SS can suffer pitting corrosion, crevice corrosion and ________ in fresh, blackish and salt water.
A) General corrosion
B) Oxidation
C) SCC
D) None of the above

Accepted Answer

300 Series Stainless Steel can suffer from Stress Corrosion Cracking (SCC) in environments such as fresh, brackish, and salt water.

Question 9

When caustic stress corrosion cracking is a concern, steam out of _________ carbon steel piping and equipment should be avoided.
A) PWHT
B) Non-PWHT
C) Ferritic
D) Hardened

Accepted Answer

Non-PWHT (Post Weld Heat Treated) carbon steel is more susceptible to caustic stress corrosion cracking, so steaming out such equipment should be avoided to prevent damage.

Question 10

Decarburization results in a __________, which can be confirmed by hardness testing.
A) Hardness
B) Softness
C) Brittleness
D) Oxidizing

Accepted Answer

Decarburization results in a reduction of carbon content which leads to a decrease in hardness and an increase in softness.

Question 11

Corrosion in boiler feedwater and condensate return systems is usually the result of dissolved gases, oxygen and _______.
A) Carbon monoxide
B) H₂O
C) Temperature
D) Carbon Dioxide

Accepted Answer

Corrosion in boiler feedwater and condensate return systems is usually the result of dissolved gases, oxygen and carbon dioxide. Dissolved carbon dioxide forms carbonic acid, which is a major cause of corrosion in these systems.

Question 12

With sulfidation, the presence of oxygen ________ corrosion
A) Increases
B) Decreases
C) Has no effect on
D) Stops

Accepted Answer

Sulfidation is a type of corrosion that occurs in environments containing sulfur compounds. The presence of oxygen increases the severity of sulfidation corrosion.

Question 13

With very few exceptions, cooling water should always be on the ________ side to minimize stagnant areas.
A) Tube
B) Shell
C) Inlet
D) Outlet

Accepted Answer

Cooling water should be on the tube side to ensure better flow distribution and minimize stagnant areas, which can lead to fouling and corrosion.

Question 14

Nitriding layers are magnetic. Therefore, _________ should be checked for magnetism as an initial screening for nitriding.
A) 300 Series SS
B) 400 Series SS
C) Duplex SS
D) Low alloy steel

Accepted Answer

Nitriding layers are magnetic because they contain iron nitrides. 300 Series SS is austenitic and non-magnetic, so it should be checked for magnetism as an initial screening for nitriding.

Question 15

A fatigue fracture is brittle and the cracks are most often __________.
A) Parallel
B) Transgranular
C) Intergranular
D) Transverse

Accepted Answer

Fatigue fractures are caused by repeated loading and unloading cycles, which can cause small cracks to form and grow until failure occurs. These cracks most often occur within the material's grains, which is known as transgranular cracking. Therefore, the best choice is B.

Question 16

________ is a form of carbon that may promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures.
A) Carbonic acid
B) Coke
C) Crude oil
D) None of the above

Accepted Answer

Coke is a form of carbon that can promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures of the furnace. This can lead to the formation of carburized layers on the surface of the furnace tubes or other equipment, which can reduce their service life and potentially lead to cracking or other forms of damage.

Question 17

Carbon dioxide (CO₂) corrosion results when CO₂ dissolves in water to form ________.
A) Carbon monoxide
B) Carbonic acid
C) Hydrofluoric acid
D) None of the above

Accepted Answer

CO₂ dissolves in water to form carbonic acid, which can result in corrosion of materials such as metals and concrete.

Question 18

Components that have been carburized may have a change in the level of ________.
A) Carbon
B) Chromium
C) Ferromagnetism
D) Stress

Accepted Answer

The answer of Components that have been carburized may have...

Question 19

Geometry, stress level, number of cycles and _________ are the predominate factors in determining the fatigue resistance of a component.
A) Temperature
B) Material properties
C) Pressure
D) Velocity

Accepted Answer

Material properties, such as strength and ductility, play a crucial role in determining the fatigue resistance of a component. Temperature, pressure, and velocity can also affect fatigue resistance but to a lesser extent compared to geometry and number of cycles.

Question 20

The primary factors affecting high temperature oxidation are metal temperature and _______.
A) Pressure
B) Alloy composition
C) Stress
D) Oxygen

Accepted Answer

Alloy composition plays a significant role in high temperature oxidation as different alloys may have different oxidation rates and tendencies. Metal temperature is also a factor, but it is indirectly related to oxidation as higher temperatures may accelerate oxidation rates. Pressure and stress may influence oxidation indirectly but are not considered primary factors. Oxygen is necessary for oxidation to occur, but it is not considered a primary factor affecting high temperature oxidation.

Exam 1: Corrosion and Materials

_______ is the primary alloying agent that affects resistance to oxidation.

To prevent carburization, select alloys with a strong surface oxide or sulfide film former such as ________.

_________ is surface initiated cracks caused by environmental cracking of 300 Series SS and some nickel based alloys under the combined action of tensile stress, temperature and an aqueous chloride environment. The presence of dissolved oxygen increases the propensity for cracking.

With cooling water corrosion, _ oxygen content tends to carbon steel corrosion rates.

Although cracks may be seen visually, crack detection for caustic stress corrosion cracking is best detected by WFMT, EC, RT and ______.

_________ is accelerated high temperature wastage of materials that occurs when contaminants in the fuel form deposits and melt on the metal surfaces.

Major factors affecting sulfidation are alloy composition, temperature and ________.

300 Series SS can suffer pitting corrosion, crevice corrosion and ________ in fresh, blackish and salt water.

When caustic stress corrosion cracking is a concern, steam out of _________ carbon steel piping and equipment should be avoided.

Decarburization results in a __________, which can be confirmed by hardness testing.

Corrosion in boiler feedwater and condensate return systems is usually the result of dissolved gases, oxygen and _______.

With sulfidation, the presence of oxygen ________ corrosion

With very few exceptions, cooling water should always be on the ________ side to minimize stagnant areas.

Nitriding layers are magnetic. Therefore, _________ should be checked for magnetism as an initial screening for nitriding.

A fatigue fracture is brittle and the cracks are most often __________.

________ is a form of carbon that may promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures.

Carbon dioxide (CO₂) corrosion results when CO₂ dissolves in water to form ________.

Components that have been carburized may have a change in the level of ________.

Geometry, stress level, number of cycles and _________ are the predominate factors in determining the fatigue resistance of a component.

The primary factors affecting high temperature oxidation are metal temperature and _______.