Question 1

Cooling water corrosion and __________ are closely related and should be considered together.

Accepted Answer

Fouling and corrosion are closely related in cooling water systems because fouling can lead to under-deposit corrosion and affect heat transfer efficiency, which can exacerbate corrosion issues.

Question 2

_________ is the main concern during start-up, shutdown and/or hydro testing for equipment/piping operating at elevated temperatures. This event can also occur in an auto refrigeration event in units processing light hydrocarbons.

Accepted Answer

The main concern during start-up, shutdown, and/or hydro testing for equipment/piping operating at elevated temperatures is brittle fracture. This occurs due to the rapid temperature changes and thermal stresses that can cause the material to become brittle and prone to cracking or fracturing. Carburization, spheroidization, and stress fractures are also important considerations in high-temperature applications, but are not the main concern during start-up, shutdown, and hydro testing.

Question 3

Dissimilar weld metal cracking forms at the toe of the weld in the heat affected zone of the ________ material.

Accepted Answer

Dissimilar weld metal cracking forms at the toe of the weld in the heat affected zone of ferritic materials.

Question 4

Welds joining dissimilar materials (ferritic) may suffer __________ related damage at high temperatures due to differential thermal expansion stresses.

Accepted Answer

The answer of Welds joining dissimilar materials (ferritic) may suffer...

Question 5

With Cl SCC, ________ levels of chloride ________ the likelihood of cracking.

Accepted Answer

Increasing levels of chloride increase the likelihood of stress corrosion cracking (SCC) in materials susceptible to chloride-induced SCC.

Question 6

All piping and equipment exposed to HF acid at any concentration with hardness levels above ________ are subject to hydrogen stress cracking.

Accepted Answer

The answer of All piping and equipment exposed to HF...

Question 7

Carbon steel and low alloy steels are subject to excessive hydrochloric acid corrosion when exposed to any concentration of HCl acid that produces a pH below______.

Accepted Answer

The answer of Carbon steel and low alloy steels are...

Question 8

Amine corrosion depends on the design, operating practices, the type of amine, amine concentration, temperature and _________.

Accepted Answer

Amine corrosion is influenced by the velocity of the fluid, as higher velocities can increase the rate of corrosion by enhancing the removal of protective films on metal surfaces.

Question 9

Stainless steels have higher coefficients of thermal expansion than carbon steel or low alloy steel or nickel based alloys and are more likely to see _________.

Accepted Answer

Stainless steels have higher coefficients of thermal expansion, which means they are more likely to experience higher stresses when subjected to temperature changes.

Question 10

For pressure vessels, inspection should focus on welds of ________ operating in the creep range.

Accepted Answer

CrMo alloys are commonly used in pressure vessels operating in the creep range. These materials are able to withstand high temperatures and pressure, but their welds are prone to defects like cracking and porosity. Therefore, inspections should focus on identifying these defects in the welds of CrMo alloy pressure vessels.

Question 11

Changing to a more corrosion resistant and/or higher hardness material _________ improve cavitation resistance.

Accepted Answer

The answer of Changing to a more corrosion resistant and/or...

Question 12

__________ caustic concentrations and ________ temperatures increase the likelihood and severity of cracking with caustic embrittlement.

Accepted Answer

Increasing caustic concentrations and temperatures can lead to more severe cracking due to caustic embrittlement. Lower concentrations and temperatures reduce the risk and severity of cracking.

Question 13

If wet electrodes or high moisture content flux weld electrodes are used to weld carbon steel, hydrogen can be charged into the steel resulting in _________.

Accepted Answer

The answer of If wet electrodes or high moisture content...

Question 14

Graphitization can be prevented by using chromium containing low alloys steels for long-term exposure above ________.

Accepted Answer

The answer of Graphitization can be prevented by using chromium...

Question 15

The major factors affecting high temperature sulfidation are the temperature, the presence of hydrogen, the concentration of H₂S and the __________.

Accepted Answer

Alloy content is a major factor affecting high temperature sulfidation because different alloys have varying resistance to sulfidation based on their composition.

Question 16

Dew point corrosion can occur if the metal temperature is below the dew point. The dew point of sulfuric acid is __________.

Accepted Answer

The dew point of sulfuric acid is typically around 280º F, which is the temperature at which sulfuric acid vapors condense and can cause corrosion.

Question 17

________ eliminates the susceptibility of most common steels to SCC.

Accepted Answer

Post weld heat treatment (PWHT) is a process that involves heating the weld zone after welding and holding it at a suitable temperature for a specified time, followed by controlled cooling. This process eliminates the susceptibility of most common steels to stress corrosion cracking (SCC). Preheat and high temperature also have benefits in reducing the risk of SCC, but they are not as effective as PWHT in eliminating susceptibility to SCC.

Question 18

The accepted way to test for temper embrittlement is ________.

Accepted Answer

Impact testing is the accepted way to test for temper embrittlement.

Question 19

Thermal fatigue cracks usually initiate on the _________ of the component. They are generally wide and filled with oxides due to the elevated temperatures.

Accepted Answer

Thermal fatigue cracks usually initiate on the surface of the component due to the elevated temperatures, and are generally wide and filled with oxides.

Question 20

Which of the following materials is not susceptible to SCC?

Accepted Answer

Carbon steel and low alloy steel are generally not susceptible to stress corrosion cracking (SCC) under most conditions, unlike 300 Series stainless steels which are more prone to SCC.

Exam 1: Corrosion and Materials