Q1. Which of these is a description of brittle fracture?
(a) Sudden rapid fracture of a material with plastic deformation
(b) Sudden rapid fracture of a material without plastic deformation
(c) Unexpected failure as a result of cyclic stress
(d) Fracture caused by reaction with sulphur compounds
Q2. Which of these materials are particularly susceptible to brittle fracture?
(a) Plain carbon and high alloy steels
(b) Plain carbon, low alloy and 300 series stainless steels
(c) Plain carbon, low alloy and 400 series stainless steels
(d) High-temperature resistant steels
Q3. At what temperature is brittle fracture most likely to occur?
(a) Temperatures above 400 8C
(b) Temperatures above the Charpy impact transition temperature
(c) Temperatures below the Charpy impact transition temperature
(d) In the range 20–110 8C
Q4. Which of these activities is unlikely to result in a high risk of brittle fracture?
(a) Repeated hydrotesting above the Charpy impact transition temperature
(b) Initial hydrotesting at low ambient temperatures
(c) Start-up of thick-walled vessels
(d) Autorefrigeration events
Q5. What type of material change will reduce the risk of brittle fracture?
(a) Use a material with lower toughness
(b) Use a material with lower impact strength
(c) Use a material with a higher ductility
(d) Use a thicker material section
Q6. Cracks resulting from brittle fracture will most likely be predominantly:
(a) Branched
(b) Straight and non-branching
(c) Intergranular
(d) Accompanied by localized necking around the crack
Q7. What is thermal fatigue?
(a) The result of excessive temperatures
(b) The result of temperature-induced corrosion
(c) The result of cyclic stresses caused by temperature variations
(d) The result of cyclic stresses caused by dynamic loadings
Q8. As a practical rule, thermal cracking may be caused by temperature swings of approximately:
(a) 200 8C &
(b) 200 8F &
(c) 100 8C &
(d) 100 8F &
Q9. Cracks resulting from thermal fatigue will most likely be predominantly:
(a) Straight and non-branching
(b) Dagger-shaped
(c) Intergranular
(d) Straight and narrow
Q10. Thermal fatigue cracking is best avoided by:
(a) Better material selection
(b) Control of design and operation
(c) Better post-weld heat treatment (PWHT)
(d) Reducing mechanical vibrations
Q1. A damage mechanism that is strongly influenced by fluid velocity and the corrosivity of the process fluid is known as:
(a) Mechanical fatigue
(b) Erosion–corrosion
(c) Dewpoint corrosion
(d) Boiler condensate corrosion
Q2. As a practical rule, atmospheric corrosion:
(a) Only occurs under insulation
(b) May be localized or general (widespread)
(c) Is generally localized
(d) Is generally widespread
Q3. A typical atmospheric corrosion rate in mils (1 mil = 0.001 inch) per year (mpy) of steel in an inland location with moderate precipitation and humidity is:
(a) 1–3 mpy
(b) 5–10 mpy
(c) 10–20 mpy
(d) 50–100 mpy
Q4. Which of these metal temperature ranges will result in the most severe CUI?
(a) 0 to 51 8C &
(b) 100 to 121 8C &
(c) 0 to 10 8C &
(d) 250+ 8C &
Q5. Which other corrosion mechanism often accompanies CUI in 300 series stainless steels?
(a) HTHA
(b) Erosion–corrosion
(c) Dewpoint corrosion
(d) SCC
