Question 1

Which of these materials are susceptible to creep damage?

Accepted Answer

All three types of steel are susceptible to creep damage as creep is a time-dependent deformation under constant stress at high temperatures, and all types of steel can undergo this type of deformation under certain conditions.

Question 2

Cavitation is best prevented by avoiding conditions that allow the absolute pressure to fall below the ___________ of the liquid or by changing the material properties.

Accepted Answer

Cavitation occurs when the absolute pressure of a liquid falls below its vapor pressure, causing bubbles to form and collapse. Therefore, preventing cavitation involves avoiding conditions that allow the absolute pressure to fall below the vapor pressure of the liquid.

Question 3

The amplitude and frequency of vibration as well as the _________ of the components are critical factors in vibration-induced fatigue.

Accepted Answer

The answer of The amplitude and frequency of vibration as...

Question 4

Since all fuels contain some amount of sulfur, sulfuric and sulfurous acid __________ can occur if the metal temperature is below this temperature.

Accepted Answer

The statement is referring to the concept of dew point corrosion, which occurs when the metal temperature falls below the dew point temperature of the fuel gases. This leads to the formation of acidic condensates, including sulfuric and sulfurous acid, which can corrode the metal surfaces. Therefore, the correct choice is C. The other two options (A and B) are not specifically related to this concept and are not applicable in this case.

Question 5

Ferritic stainless steels are usually not used in __________ applications.

Accepted Answer

Ferritic stainless steels are generally not used in pressure boundary applications due to their lower toughness and ductility compared to austenitic stainless steels, which makes them less suitable for handling high pressure.

Question 6

Hydrogen blisters may form as surface bulges on the ID, the OD on within the wall thickness of a pipe or pressure vessel. Blistering occurs from hydrogen generated by ______, not hydrogen gas from the process stream.

Accepted Answer

Blistering occurs from hydrogen generated by corrosion, where atomic hydrogen diffuses into the metal and forms molecular hydrogen, creating pressure that leads to blistering.

Question 7

Which of the following materials is not susceptible to high temperature hydrogen attack?

Accepted Answer

All of the materials listed are susceptible to high temperature hydrogen attack.

Question 8

The best way to prevent 885º F embrittlement is to use low ________ alloys, or to avoid exposing the susceptible material to the embrittling range.

Accepted Answer

Low ferrite alloys are the best option to prevent 885º F embrittlement. This type of embrittlement occurs when ferrite grains become coarser, leading to a decrease in toughness and ductility. Using low ferrite alloys can prevent this by limiting the formation of coarse ferrite grains. Avoiding exposure to the embrittling range is also important, but may not always be possible in certain applications. Choices A and B are not correct because austenite and martensite are not directly related to the prevention of 885º F embrittlement. Choice D is not correct because while chromium can improve corrosion resistance, it is not directly related to preventing embrittlement.

Question 9

Stress ruptures are characterized by _________ failures and are usually accompanied by thinning at the fracture surface.

Accepted Answer

Stress ruptures are a type of failure that occurs under long-term exposure to high stress, at temperatures well below the melting point of the material. These failures are characterized by fish-mouth shaped fractures and are usually accompanied by thinning at the fracture surface.

Question 10

At elevated temperature, the carbide phases in certain carbon steels are unstable and may decompose into _______. This decomposition is known as graphitization.

Accepted Answer

At elevated temperatures, carbide phases in carbon steels can decompose into graphite nodules, a process known as graphitization.

Question 11

High temperature hydrogen attack results from exposure to hydrogen at elevated temperatures and pressures. The hydrogen reacts with __________ in steel to produce _________, which cannot diffuse through the steel. The loss of carbides causes an overall loss in strength.

Accepted Answer

High temperature hydrogen attack involves hydrogen reacting with carbides in steel to form methane, which cannot diffuse through the steel, leading to a loss in strength.

Question 12

Different organisms thrive on different nutrients including inorganic substances (Sulfur, H₂S), and organic substances (Hydrocarbons, Organic acids). In addition, all organisms require a source of carbon, nitrogen and _______ for growth.

Accepted Answer

All organisms require a source of carbon, nitrogen, and phosphorus for growth. Oxygen and water are necessary for some organisms, but not all. Manganese is a trace element and is not essential for growth in large quantities.

Question 13

The most important factors affecting graphitization are the chemistry, stress, temperature and _______.

Accepted Answer

Time at exposure is the most important factor affecting graphitization after chemistry, stress, and temperature. Graphitization occurs over an extended period of time at elevated temperatures, usually above 1000°C, but it can be accelerated by the presence of catalysts or certain dopants.

Question 14

_________ is most likely found in hard weld and heat-affected zones and in high strength components.

Accepted Answer

SSC (sulfide stress cracking) is commonly found in hard weld and heat-affected zones and in high strength components. HIC (hydrogen induced cracking) is commonly found in wet H2S environments, SOHIC (stress-oriented hydrogen-induced cracking) is commonly found in pipelines and pressure vessels, and blistering is a type of corrosion commonly found in environments with high temperatures and pressures.

Question 15

In design and fabrication, it is advisable to avoid sharp changes in cross section, such as short radius fillets or undercut that can give rise to _________. Long-seam welds are particularly susceptible to reheat cracking due to mismatch caused by fit up problems.

Accepted Answer

The answer of In design and fabrication, it is advisable...

Question 16

Creep damage is found in high temperature equipment operating above the ________. Fired heater tubes and components, Catalytic reactors, FCC reactors and FCC fractionator and regenerator internals all operate in or near this.

Accepted Answer

Creep damage occurs in high temperature equipment operating above the creep range temperature. The other options, Transition range and MADT, do not refer to the temperature range at which creep damage may occur.

Question 17

Amine stress corrosion cracking is most often associated with lean amine services. The pure alkanolamine does not cause cracking. Cracking in rich amine services are most often associated with _______ problems.

Accepted Answer

Cracking in rich amine services is most often associated with the presence of wet H₂S.

Question 18

The loss in strength from spheroidization (Softening) is usually accompanied by a(n) _________ in ductility, which allows for deformation at stress concentrations.

Accepted Answer

Spheroidization, or softening, results in an increase in ductility. This increase in ductility allows for deformation at stress concentrations, despite the loss in strength.

Question 19

Hardness levels above ________ are highly susceptible to hydrogen stress cracking (HF). Time-to-failure decreases as the hardness increases.

Accepted Answer

The answer of Hardness levels above ________ are highly susceptible...

Question 20

__________ are the most common type of equipment susceptible to carburization in the refining industry.

Accepted Answer

Heater tubes are the most common type of equipment that are susceptible to carburization in the refining industry. Carburization occurs when carbon molecules diffuse into the metal of the equipment at high temperatures, leading to the formation of brittle carbides that can cause cracking and other forms of damage. Other types of equipment, such as reactors, heat exchangers, and fin fans, may also be affected by carburization to some extent, but not to the same degree as heater tubes.

Exam 1: Corrosion and Materials