Question 1

Low creep ductility is _____ prevalent at the lower temperatures in the creep range. Or low stresses in the upper creep range.

Accepted Answer

A)  More 
B)  Less 
C)  Equally 
D)  None of the above

Question 2

With sulfuric acid corrosion, carbon steel corrosion rates increase significantly if the flow velocity exceeds about ________m fps or at acid concentrations below _________.

Accepted Answer

A)  6-9, 80% 
B)  5-7, 75% 
C)  2-3, 65% 
D)  4-6, 85%

Question 3

In HF service, carbon steel forms a protective _________ scale in dry concentrated acid. Loss of the protective scale through high velocities or turbulence will result in greatly accelerated corrosion rates.

Accepted Answer

A)  Chloride 
B)  Fluoride 
C)  Iron sulfide 
D)  Iron oxide

Question 4

A prime location for erosion is:

Accepted Answer

A)  In catalyst piping. 
B)  Downstream of a gate valve. 
C)  Any superheated steam piping. 
D)  Upstream of a pump.

Question 5

________ of a component is the most important factor in determining a components resistance to mechanical fatigue.

Accepted Answer

A)  Design 
B)  Temperature 
C)  Stress 
D)  Pressure

Question 6

Although the loss of toughness from temper embrittlement is not evident at operating temperatures, equipment that is temper embrittled may be susceptible to ________ during start-up and shutdown.

Accepted Answer

A)  Thermal fatigue 
B)  Cyclic stress 
C)  Notch toughness 
D)  Brittle fracture

Question 7

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

Accepted Answer

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

Question 8

The regenerator reboiler and the regenerator are areas where the temperature and __________ of the amine stream are the highest and can cause significant corrosion problems.

Accepted Answer

A)  Pressure 
B)  Stress 
C)  Turbulence 
D)  Concentration

Question 9

What structure is 304 stainless steel?

Accepted Answer

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

Question 10

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

Accepted Answer

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

Question 11

Dissimilar weld metal cracking occurs because the coefficients of thermal expansion between ferritic steels and 300 Series stainless steels differ by ________ or more.

Accepted Answer

A)  10% 
B)  15% 
C)  20% 
D)  30%

Question 12

______ 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.

Accepted Answer

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

Question 13

Phosphoric acid corrosion is usually found in ________ areas.

Accepted Answer

A)  High velocity 
B)  Low velocity 
C)  High temperature 
D)  Low temperature

Question 14

Mechanical fatigue can cause cracks that initiate from the surface and often form a:

Accepted Answer

A)  Clam shell appearance. 
B)  Snail shell appearance. 
C)  Turtle shell appearance. 
D)  Shell Oil shell appearance. 
E)  Taco shell appearance.

Question 15

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.

Accepted Answer

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

Question 16

Which of the following is not a major factor associated with corrosion by sulfidation?

Accepted Answer

A)  Alloy composition 
B)  Operating pressure 
C)  Operating temperature 
D)  Sulfur content

Question 17

Which of the following is not a critical factor that contributes to a brittle fracture?

Accepted Answer

A)  The material's fracture toughness 
B)  Maximum operating temperature 
C)  Stress concentration at a flaw 
D)  Magnitude of the residual stresses

Question 18

Damage due to __________ is not visible and can only be observed by metallographic examination.

Accepted Answer

A)  Galvanic corrosion 
B)  Brittle fracture 
C)  Cavitation 
D)  Graphitization

Question 19

A minimum of ________ to ______ molybdenum is needed in an alloy to resist naphthenic acid corrosion.

Accepted Answer

A)  2%, 3% 
B)  1 ½ %, 2 ½ % 
C)  2%, 2 ½ % 
D)  1%, 2%

Question 20

________ and _______ damage develop without applied or residual stress so that PWHT will not prevent them from occurring.

Accepted Answer

A)  SOHIC, Blistering 
B)  SCC, SOHIC 
C)  HIC, SCC 
D)  Blistering, HIC

Exam 1: Corrosion and Materials