571 Exercises, Rev2

API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining Industry

Rev. 2 10/06 DTM Enterprises Technical Training Division 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 oF B. 1150 oF C. 1300 oF

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. 300oF or higher B. 400oF or higher C. 500oF 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

571 Exercises, Rev2

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