Deck 1: Corrosion and Materials

Question 1

Cracks that are typically straight, non-branching, and devoid of any associated plastic deformation are likely associated with which type of failure?

A) Stress corrosion cracking
B) Brittle fracture
C) Thermal fatigue
D) Temper embrittlement

Answer 1

B

Question 2

The sudden rapid fracture under stress (residual or applied) where the material exhibits little or no evidence of ductility or plastic deformation is called _________.

A) 885º F Embrittlement
B) Temper Embrittlement
C) Stress Corrosion Cracking
D) Brittle Fracture

Answer 2

D

Question 3

At high temperatures, metal components can slowly and continuously deform under load below the yield strength. This time dependent deformation of stressed components is known as _______?

A) Creep
B) Ductility
C) Softening
D) Hardening

Answer 3

A

Question 4

Which of the following can be affected by 885º F Embrittlement?

A) 410 SS
B) 430 SS
C) 308 SS
D) Alloy 2205
E) A, B and D

Question 5

Thermal fatigue cracks propagate ________ to the stress and are usually dagger shaped, transgranular and oxide-filled.

A) Axial
B) Diagonal
C) Transverse
D) Angular

Question 6

Liquid metal embrittlement can occur if 300 Series SS comes in contact with molten _______.

A) Copper
B) Mercury
C) Zinc
D) Lead

Question 7

__________ is a change in the microstructure of certain carbon steels and 0.5 Mo steels after long term operation in the 800º F to 1100º F range.

A) Graphitization
B) Softening
C) Temper Embrittlement
D) Creep

Question 8

With CUI, corrosion rates __________ with increasing metal temperatures up to the point where the water evaporates quickly.

A) Decrease
B) Increase
C) Stay the same
D) None of the above

Question 9

General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activities is called ________.

A) Flue Gas Corrosion
B) Atmospheric Corrosion
C) Cooling Water Corrosion
D) None of the Above
E) All of the Above

Question 10

What structure is 304 stainless steel?

A) Martensitic
B) Austenitic
C) Duplex
D) Ferritic

Question 11

________ is a form of erosion caused by the formation and instantaneous collapse of innumerable tiny vapor bubbles.

A) Condensate corrosion
B) Cavitation
C) Dew-Point corrosion
D) Atmospheric corrosion

Question 12

Which of the following metals is the most anodic?

A) Zinc
B) Carbon Steel
C) Nickel
D) Monel

Question 13

Inspection for wet H2S damage generally focuses on _____ and ______.

A) Weld seams
B) Nozzles
C) Trays
D) Down comers
E) A and B

Question 14

For 5Cr-0.5Mo, what is the threshold temperature for creep?

A) 500º F
B) 800º F
C) 600º F
D) 700º F

Question 15

Soil to Air interface areas are usually more susceptible to corrosion than the rest of the structure because of ___________ and __________ availability.

A) Moisture
B) Bacteria
C) Oxygen
D) B and C
E) A and C

Question 16

Cracking of dissimilar weld metals occurs on the _________ side of a weld between an austenitic and a Ferritic material operating at high temperatures.

A) Austenitic
B) Ferritic
C) Anodic
D) Cathodic

Question 17

_________ is the result of cyclic stress caused by variations in temperature.

A) Creep
B) Thermal Fatigue
C) Cyclic Cracking
D) Stress Corrosion Cracking

Question 18

Low alloy steels contain a maximum of _______ chrome.

A) 5%
B) 6%
C) 7.5%
D) 9%

Question 19

________ has been a major problem on coke drum shells.

A) Thermal fatigue
B) Stress cracking
C) Erosion
D) Temper embrittlement

Question 20

Carburization can be confirmed by substantial increases in _______ and loss of __________.

A) Hardness
B) Tensile Strength
C) Ductility
D) A and B
E) A and C

Question 21

Amine cracking has been reported down to ambient temperatures with some amines. __________ temperatures and stress levels _______ the likelihood and severity of cracking.

A) Increasing increases
B) Increasing, decreases
C) Decreasing increases
D) Increasing, reduces

Question 22

At a given pressure, the H₂S concentration in the sour water _________ as temperature _________.

A) Increases, increases
B) Decreases, decreases
C) Increases, decreases
D) Decreases, increases

Question 23

Which API RP recommends programs to monitor small-bore piping, flange faces, blistering and HIC/SOHIC in HF alky units?

A) 574
B) 751
C) 571
D) 980

Question 24

______ is similar to HIC but is a potentially more damaging form of cracking which appears as arrays of cracks stacked on top of each other. The result is a through thickness crack that is perpendicular to the surface and is driven by high levels of stress.

A) MIC
B) SOHIC
C) Sulfuric SCC
D) None of the above

Question 25

_________ is a change in the microstructure of certain carbon steels and 0.5Mo steels after long-term operation in the 800º F to 1100º F range that may cause a loss in strength, ductility and/or creep resistance.

A) Embrittlement
B) Carburization
C) Graphitization
D) Sensitization

Question 26

__________ is usually found in aqueous environments or services where water is sometimes or always present, especially where stagnant or low-flow conditions allow the growth of microorganisms.

A) MIC
B) HIC
C) SOHIC
D) None of the above

Question 27

The grain size has an important influence on the high temperature ductility and on the reheat cracking susceptibility. A ________ grain size results in _______ ductile heat affected zones, making the material more susceptible to reheat cracking.

A) Large, More
B) Small, Less
C) Large, Less
D) Small, More

Question 28

Carbonate stress corrosion cracking usually occurs at welds or cold worked areas that __________.

A) Have been stressed relieved
B) Have not been stressed relieved
C) Have high residual stress
D) Have high-applied stress

Question 29

Nitriding is usually confined to the surface of most components and will have a dull, ______ appearance. In more advanced stages, the material will exhibit very hard surface hardness.

A) Gray
B) Black
C) Brown
D) White

Question 30

Amine stress corrosion cracking is a term applied to the cracking of steels under the combined actions of ________ and __________ in aqueous alkanolamine systems used to remove/absorb H₂S and/or CO₂ and their mixtures from various gas and liquid hydrocarbon streams.

A) Temperature, pressure
B) Pressure, stress
C) Temperature, corrosion
D) Tensile stress, corrosion

Question 31

Permanent deformation occurring at relatively low stress levels as a result of localized overheating is called ________.

A) Stress cracking
B) Brittle fracture
C) Temper embrittlement
D) Stress rupture

Question 32

Equipment that is temper embrittled may be susceptible to _______ during start-up and shutdown.

A) Creep
B) Thermal fatigue
C) Brittle fracture
D) Stress fatigue

Question 33

__________ is a form of cracking that results when certain molten metals come in contact with specific alloys. Cracking can be very sudden and brittle in nature.

A) SCC
B) LME
C) AET
D) SOHIC

Question 34

With chloride stress corrosion cracking, __________ temperatures ________ the susceptibility for cracking.

A) Decreasing, Increases
B) Increasing, Increases
C) Increasing, Decreases
D) Decreasing, Eliminates

Question 35

Low creep ductility is __________ severe in high tensile strength materials and welds.

A) More
B) Less
C) Usually
D) Not

Question 36

Carbon steel is susceptible to SCC when used in ___________ service.

A) Hydrogen
B) Ammonia
C) High temperature
D) High pressure

Question 37

Nickel based alloys usually contain ________ nickel.

A) ≥30%
B) ≥20%
C) ≥10%
D) ≥12%

Question 38

_____________ usually occurs when a colder liquid contacts a warmer metal surface.

A) Brittle fracture
B) Thermal fatigue
C) Thermal shock
D) Stress rupture

Question 39

Weld heat affected zone graphitization is most frequently found in the heat affected zone adjacent to welds in a narrow band, corresponding to the low temperature edge of the heat affected zone. In multi-pass welded butt joints, these zones overlap each other covering the entire cross section. Because of its appearance, this type of graphitization is called________.

A) Half-moon
B) Eyebrow
C) Radii
D) None of the above

Question 40

In order for PASCC to occur the material must be ______.

A) PWHT
B) Non-PWHT
C) Sensitized
D) Austenitic

Question 41

Which of these materials are susceptible to creep damage?

A) Carbon steel
B) Stainless steel
C) Low alloy steel
D) All of the above

Question 42

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.

A) Minimum pressure
B) Pressure/vapor ratio
C) Maximum pressure
D) Vapor pressure

Question 43

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

A) Velocity
B) Temperature
C) Fatigue resistance
D) Material properties

Question 44

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

A) Corrosion
B) Pitting
C) Dew point corrosion
D) All of the above

Question 45

Ferritic stainless steels are usually not used in __________ applications.

A) Non-pressure boundary
B) Pressure boundary
C) High temperature
D) Low temperature

Question 46

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.

A) H₂S
B) Corrosion
C) Hydriding
D) Sulfur

Question 47

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

A) 300 Series SS
B) 5 Cr-1Mo
C) 9Cr-1Mo
D) All of the above

Question 48

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

A) Austenite
B) Martensite
C) Ferrite
D) Chromium

Question 49

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

A) Rapid
B) Fish-mouth
C) Tensile
D) None of the above

Question 50

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

A) Silicon
B) Graphite nodules
C) Carbon dust
D) Graphite dust

Question 51

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.

A) Carbides, oxygen
B) Alloys, hydrogen dioxide
C) Carbides, methane
D) Hydrogen dioxide, H₂S

Question 52

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.

A) Oxygen
B) Water
C) Manganese
D) Phosphorous

Question 53

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

A) Velocity
B) Time at exposure
C) Pressure
D) Ductility

Question 54

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

A) HIC
B) SSC
C) SOHIC
D) Blistering

Question 55

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.

A) Stress concentrations
B) Cracking
C) Circumferential stress
D) All of the above

Question 56

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.

A) Transition range
B) MADT
C) Creep range
D) None of the above

Question 57

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.

A) H₂S
B) Stress
C) Wet H₂S
D) Temperature

Question 58

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

A) Increase
B) Decrease
C) Reduction
D) Yield

Question 59

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

A) 225 BHN
B) 237 BHN
C) 241 BHN
D) 247 BHN

Question 60

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

A) Reactors
B) Heat exchangers
C) Heater tubes
D) Fin Fans

Question 61

Which of the following alkanolamine systems is the most aggressive in causing amine corrosion?

A) Monoethanolamine (MEA)
B) Diglycolamine (DGA)
C) Diethanolamine (DEA)
D) Methyldiethanolamine (MDEA)

Question 62

Steel hardness, __________ and stress are critical factors in causing hydrogen stress cracking.

A) Temperature
B) Alloy composition
C) Strength
D) None of the above

Question 63

Hydrochloric acid corrosion is a general and localized corrosion and is very aggressive to most common materials of construction. Damage in refineries is often associated with dew point corrosion in which vapors containing _______ and hydrogen chloride condense from the overhead stream of a distillation, fractionation, or stripping tower.

A) O₂
B) O
C) H₂O
D) CO₂

Question 64

General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activity is called _______.

A) Cooling water corrosion
B) Oxidation
C) MIC
D) None of the above

Question 65

When connected to a more anodic material, titanium may suffer severe __________.

A) Corrosion
B) Hydriding
C) Stress
D) Notch toughness

Question 66

Which of the following materials is susceptible to CO₂ corrosion?

A) Carbon steel
B) Stainless steel
C) Duplex stainless steel
D) Both B and C

Question 67

________ usually occurs when a colder liquid contacts a warmer metal surface.

A) Stress cracking
B) Thermal fatigue
C) Thermal shock
D) Stress shock

Question 68

________ is a loss in toughness due to a metallurgical change that can occur in alloys containing a ferrite phase, as a result of exposure in the temperature range 600º F to 1000º F.

A) Caustic embrittlement
B) Notch toughness
C) 885º F embrittlement
D) Ductile embrittlement

Question 69

Increasing chromium content in the alloy improves resistance to sulfidation. However, there is little improvement with increasing chromium content until about ________ Cr.

A) 3-5
B) 5-7
C) 7-9
D) 9-12

Question 70

_________ is the sudden rapid fracture under stress (residual or applied) where the material exhibits little or no evidence of ductility or plastic deformation.

A) Thermal fatigue
B) Thermal shock
C) Brittle fracture
D) Stress fracture

Question 71

Caustic embrittlement cracking can be effectively prevented by means of PWHT at a temperature of _______.

A) 1100º F
B) 1150º F
C) 1200º F
D) 1250º F

Question 72

If the BHN is 400-500 it may indicate __________.

A) Carburization
B) Hydriding
C) Temper embrittlement
D) Caustic embrittlement

Question 73

__________ is a form of stress corrosion cracking normally occurring during shutdowns, startups or during operation when air and moisture are present. Cracking is due to sulfur acids forming from sulfide scale, air and moisture acting on sensitized stainless steel.

A) Caustic SCC
B) Chloride SCC
C) Polythionic acid SCC
D) None of the above

Question 74

The level of creep damage is a function of the material and the coincident _________ level at which the creep deformation occurs.

A) Pressure/Temperature
B) Pressure/Stress
C) Temperature/Stress
D) None of the above

Question 75

Titanium should not be used in known hydriding services such as _____ or ______.

A) Caustic, amine
B) Amine, sour water
C) Sour water, Alkylation
D) All of the above

Question 76

The presence of ________ in H₂S streams increases the severity of high temperature sulfide corrosion at temperatures above about 500º F

A) Amine
B) Hydrogen
C) Sulfides
D) All of the above

Question 77

Which of these materials is not susceptible to amine cracking?

A) Carbon steel
B) 300 Series SS
C) 400 Series SS
D) Both B and C

Question 78

Convert these temperatures - 156º C and 450º F

A) 304º F, 151º C
B) 284º F, 218º C
C) 312º F, 232º C
D) 296º F, 246º C

Question 79

The graphitization rate ____________ with increasing temperature

A) Increases
B) Decreases
C) Stops
D) Proceeds

Question 80

With hydrofluoric acid corrosion, corrosion rates increase with _______ temperatures and ______ HF concentrations.

A) Increasing, decreasing
B) Decreasing, increasing
C) Increasing, increasing
D) Decreasing, decreasing