571 exercises, rev2

API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Rev. 2 10/06 DTM Enterprises Technical Training Division Page 1 of 11
281-330-9542 – www.DTM-Enterprises.org
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4.2.3 Temper Embrittlement
1. Temper Embrittlement is a ________ in toughness that can occur in some low alloy
steels.
A. increase
B. decrease
2. Equipment subject to Temper Embrittlement is normally those that operate at
___________.
A. higher temperatures
B. lower temperatures
3. Temper Embrittlement can be readily found by Visual and other NDE methods.
A. True
B. False
4. A common method of monitoring for Temper Embrittlement is to _____________
inside the reactor. Samples are periodically removed from these blocks for impact
testing to monitor progress of temper embrittlement or until a major repair issue
arises.
A. install blocks of the original heats of the alloy steel
B. install a block of a similar heat of the alloy steel
C. install Temper Embrittlement probes
4.2.7 Brittle Fracture
5. Brittle fracture is characterized by ________________________________.
A. a slow cracking that develops over an extended period of time
B. a high strain rate that leads to a sudden failure
C. a sudden rapid failure under stress
6. The main concern for brittle fracture is ______________________.
A. during shutdown
B. during startup
C. during startup and shutdown

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7. Brittle fracture cracks will typically be straight, non-branching, and largely devoid of
any associated plastic deformation.
A. True
B. False
8. Inspection for brittle fracture is______________________________.
A. dependent on accessibility to internal surfaces
B. dependent on expensive NDE methods such as Acoustic Emissions
C. not normally done
4.2.9 Thermal Fatigue
9. The materials subject to thermal fatigue are __________________________.
A. high chrome alloys
B. all materials of construction
C. austenitic stainless steels
10. Thermal fatigue cracks usually initiate _______________of the component.
A. on the surface
B. in the through thickness
C. on the interior
11. Thermal fatigue is best prevented through design and operation to minimize thermal
stresses and thermal cycling. Some methods to help prevent thermal fatigue include
____________________________________________.
A. blend grinding the weld profile of components to remove stress raisers
B. controlled rates of heat during startup and shutdown
C. designs that incorporate sufficient flexibility
D. All of the above
12. External ________inspection can be used for non-intrusive inspection for internal
thermal fatigue cracking and where reinforcing pads prevent nozzle examination.
A. Dye penetrant
B. Shear Wave UT
C. Visual

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4.2.14 Erosion / Erosion-Corrosion
13. Erosion - Corrosion is ______________________________.
A. the accelerated mechanical removal of surface material as a result of relative
movement between, or impact from solids, liquids, vapor or any combination
thereof
B. removing protective films or scales by exposing the metal surface to further
corrosion
14. Increasing the hardness of the metal substrate is _____________________.
A. always a good method to prevent erosion from occurring
B. not always a good method to prevent erosion from occurring
15. Visual examination of suspected or troublesome areas, as well as UT checks or RT
can be used to detect the extent of metal loss.
A. True
B. False
16. Which of the following is not a form of erosion or erosion - corrosion?
A. cavitation
B. fretting
C. carburization
4.2.16 Mechanical Failure
17. One of the properties of mechanical fatigue is that it typically happens
___________.
A. well below yield strength of the material
B. well above yield strength of the material
C. at the yield strength of the material
18. Fatigue cracks usually initiate on the surface _______________under cyclic
loading.
A. at openings only
B. at notches or stress raisers
C. underneath reinforcement pads only

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19. Heat treatment can have a significant effect on the toughness and hence fatigue
resistance of a metal. In general ___________tend to perform better
than___________.
A. coarse grained microstructures - finer grained
B. medium grained microstructures - coarse grained
C. finer grained microstructures - coarse grained
20. An example of a component that might exhibit mechanical fatigue due to thermal
cycling is a ______________________________________.
A. large bore piping systems
B. coker drum
C. high pressure drop control valves
21. NDE monitoring for mechanical fatigue might include _______________________.
A. SWUT, RT and MT
B. PT, MT and SWUT
C. RT, PT and MT
4.3.2 Atmospheric Corrosion
22. Materials that might be affected by atmospheric corrosion include ______________.
A. Carbon steel, low alloy steels and copper alloyed aluminum
B. Carbon steel, low alloy steels and alloyed brasses
C. Carbon steel, low alloy steels and the 400 series stainless steels
23. Piping on supports are often very prone to atmospheric corrosion due to ________.
A. long horizontal runs
B. being located next over sprays and leaks
C. water entrapment between the pipe and the supports
24. The method(s) that can be used for inspection to find atmospheric corrosion
are_________________.
A. Visual and RT
B. UT and Visual

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4.3.3 Corrosion Under Insulation (CUI)
25. Materials that might be affected by CUI include_______________________.
A. Carbon steel, low alloy steels 300 and 600 Series SS
B. Carbon steel, low alloy steels 500 Series SS and duplex stainless steels
C. Carbon steel, low alloy steels 300 Series SS and duplex stainless steels
26. It is known that 300 Series SS, 400 Series SS and duplex SS are subject to pitting
and localized corrosion. The 300 series are also subject to what form of attack if
chlorides are present?
A. ________________________________________
27. Preventing CUI calls for careful selection of insulating materials. Therefore
__________ materials will hold less water against the vessel/pipe wall than
___________and, are potentially be less corrosive.
A. closed-cell foam glass - mineral wool
B. mineral wool - closed-cell foam glass
C. asbestos - closed-cell foam glass
28. The recommended technique for identifying wet insulation and potential CUI is
____________.
A. Profile radiography
B, Neutron backscatter
C. Insulation removal
4.3.4 Cooling Water Corrosion
29. Cooling water corrosion is a general or localized corrosion of carbon steels and
other metals caused by _______________________________________.
A. dissolved salts, gases, organic compounds or microbiological activity
B. Low pH, inert gases, inorganic compounds or microbiological activity
C. High pH, gases, organic compounds or microbiological activity
30. ________cooling water outlet temperatures and or process side inlet temperatures
tend to increase corrosion rates as well as fouling tendency.
A. Decreasing
B. Increasing

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31. Cooling water corrosion ________areas will appear as grooving along the weld
fusion lines.
A. at GTAW welds
B. at ERW welds
C. at nozzle welds
32. Cooling water should be monitored for variables that affect corrosion and fouling.
Below list the main variables that affect cooling water corrosion.
A. _______________________________
B. _______________________________
C. _______________________________
D. _______________________________
E. _______________________________
F. _______________________________
G. _______________________________
4.3.5 Boiler Water Condensate Corrosion
33. Corrosion in boiler feed water and condensate return system is usually the result of
dissolved gases, such as____________________________.
A. oxygen and sulfur phosphates
B. carbon dioxide and low pH amine
C. oxygen and carbon dioxide
34. Corrosion from oxygen tends to be pitting type damage and can show up any where
in the system, but is most aggressive in __________________________.
A. equipment such as closed heaters and economizers
B. boiler tubes in the radiant section
C. boiler tubes in the convection section
35. _______________is the common monitoring tool used to assure that the various
treatment systems are performing in a satisfactory manner.
A. pH measurement alone
B. complete water analysis
C. oxygen content

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4.4.2 Sulfidation
36. Which of the following alloys form sulfides at a lower temperature than carbon
steel?
A. copper alloys
B. nickel alloys
C. aluminum alloys
37. Generally the resistance to Sulfidation in iron and nickel base alloys increases as
the _____________ content increases.
A. nickel
B. molybdenum
C. chromium
38. Inspection methods to determine thinning by Sulfidation include ___and ___.
A. UT thickness and VT
B. UT thickness and Profile RT
C. EC and Profile RT
39. Sulfidation is also known as __________________.
A. Sulfurous Oxide Attack (SOA)
B. High Temperature Sulfide Attack (HTSA)
C. Sulfidic Corrosion (SC)
4.5.1 Chloride Stress Corrosion Cracking (Caustic Embrittlement)
40. The description of Chloride Stress Corrosion Cracking is surface initiated cracks
caused by environmental cracking of 300 Series SS and some nickel base alloys
under the combined action of tensile stress, temperature and an aqueous chloride
environment. This condition is accelerated by__________.
A. increasing temperature
B. decreasing temperature
C. decreasing chloride
41. Which of the following alloys is highly susceptible to CLSCC?
A. nickel
B. duplex stainless steel
C. 300 series stainless steel

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42. SCC usually occurs at pH values_____. At lower pH values, uniform corrosion
generally predominates. SCC tendency decreases toward the alkaline pH region.
A. above 2
B. below 2
C. above 4
43. Inspection for CL SCC can be detected by using which of the following NDE
methods?
A. VT
B. PT
C. Both methods above
4.5.2 Corrosion Fatigue
44. Corrosion fatigue can affect __________________ materials.
A. Carbon Steel
B. Austenitic Stainless Steel
C. All metals and alloys
45. The fatigue fracture is brittle and the cracks are most often _________, as in stress-
corrosion cracking, but not branched, and often results in propagation of
____________cracks.
A. transgranular - multiple parallel
B. intergranular - multiple parallel
C. transgranular - multiple radial
46. Corrosion fatigue is usually found in Deaerators by using __________ NDE.
A. VT
B. MT
C. WFMT

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4.5.3 Caustic Stress Corrosion Cracking (Caustic Embrittlement)
47. Caustic embrittlement is a form of stress corrosion cracking characterized by
surface-initiated cracks that occur in piping and equipment exposed to caustic,
primarily adjacent to___________.
A. non-PWHT welds
B. PWHT welds
C. nozzles and other openings
48. Crack propagation rates increase dramatically with temperature and can sometimes
grow through wall in ____________________________.
A. a matter of a few weeks
B. a matter of hours or days
C. a matter of a few months
49. Caustic embrittlement is often found in piping and equipment that handles caustic.
It may also be found in a process unit that______________________.
A. removes naphtha
B. mercaptans
C. Light Gas Oil
50. Prevention of cracking in carbon steels can be achieved by PWHT to a temperature
of __________________.
A. 1250 o
F
B. 1150 o
F
C. 1300 o
F
5.1.2.3 Wet H2S Damage (Blistering/HIC/SOHIC/SCC)
51. Name the four types of Wet H2S Damage.
A. ________________________________________________________
B. ________________________________________________________
C. ________________________________________________________
D. ________________________________________________________

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52. Blistering, HIC, and SOHIC damage have been found to occur between ambient
and _______________.
A. 300o
F or higher
B. 400o
F or higher
C. 500o
F or higher
53. Typical low-strength carbon steels used in refinery applications should be controlled
to produce weld hardness <200 HB. These steels are not usually subject to SCC at
hardness below ___________________.
A. 200 HB
B. 237 HB
C. 190 HB
53. Blistering and HIC damage _________ prevented with PWHT.
A. cannot be
B. can be
C. may be
5.1.3.1 High Temperature Hydrogen Attack (HTHA)
54. HTHA occurs when hydrogen reacts with ______in steel to form ______which
cannot diffuse through the steel.
A. iron - iron oxide
B. carbon - carbon dioxide
C. carbides - methane
55. Internal visual inspection for blisters ______________ HTHA.
A. will always indicate
B. may not indicate
C. does not indicate
56. Acoustic Emission Testing is a proven method for finding HTHA.
A. True
B. False

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Answer Key API RP 571 Damage Mechanisms
1. B 36. A
2. A 37. C
3. B 38. B
4. A 39. C
5. C 40. A
6. C 41. C
7. A 42. A
8. C 43. C
9. B 44. C
10. A 45. A
11. D 46. C
12. B 47. A
13. B 48. B
14. B 49. B
15. A 50. B
16. C 51. A. Hydrogen Blistering
17. A B. Hydrogen Induced Cracking
18. B C. Sulfide Stress Corrosion Cracking
19. C D. Stress Oriented Hydrogen Induced Cracking
20. B 52. A
21. B 53. B
22. A 54. C
23. C 55. B
24. B 56. B
25. C
26. A. Stress Corrosion Cracking
27. A
28. B
29. A
30. B
31. B
32. A. pH
B. Oxygen Content
C. Cycles of Concentration
D. Biocide Residual
E. Biological Activity
F. Cooling Water Outlet Temperature
G. Hydrocarbon Contamination& Process Leaks
33. C
34. A
35. B

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