API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 191:

  Decarburization damage is normally verified by:

  A. Impact testing
  B. Tensile testing
  C. Bend testing
  D. Metallographic testing
  D. Metallographic testing

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  According to API RP 571, under the section on High Temperature Hydrogen Attack (HTHA) and Decarburization:

  "Decarburization is typically confirmed by metallographic examination. This method reveals carbon loss and microstructural changes such as spheroidization or softening of pearlite."

  "Tensile or impact testing may not reveal early-stage decarburization, especially in partial layers."

  Therefore, metallographic testing is the standard and most direct method to confirm decarburization damage, making option D correct.

• Question 192:

  What type of damage is affected by higher hydrogen partial pressures?

  A. Hydrogen-induced cracking
  B. Hydrogen embrittlement
  C. Hydrogen blistering
  D. High temperature hydrogen attack
  D. High temperature hydrogen attack

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  According to API RP 941 and API RP 571 High Temperature Hydrogen Attack (HTHA) is highly, influenced by hydrogen partial pressure at elevated temperatures:

  "The likelihood and rate of HTHA increase with both temperature and hydrogen partial pressure. Operating beyond established material limits on the Nelson Curves can lead to internal decarburization and methane formation in the steel."

  API RP 571, Section 4.2.1.3 - High Temperature Hydrogen Attack) Therefore, among all listed damage types, HTHA is the most directly affected by high hydrogen partial pressures, making option D correct.

• Question 193:

  Which damage mechanism will not benefit much from PWHT mitigation?

  A. Carbonate stress corrosion cracking
  B. Sulfide stress cracking
  C. Hydrogen-induced cracking
  D. Amine stress corrosion cracking
  C. Hydrogen-induced cracking

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  API RP 571 discusses Hydrogen-Induced Cracking (HIC) and Blistering:

  "Postweld heat treatment (PWHT) does not significantly reduce susceptibility to HIC, as the mechanism is primarily driven by hydrogen charging in wet H#S environments and steel cleanliness, not residual stresses."

  "PWHT is more effective for SSC, SOHIC, and other stress-driven mechanisms."

  Thus, HIC will not benefit much from PWHT, making option C correct.

• Question 194:

  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
  A. Creep

• Question 195:

  SCC tendency ________ towards the alkaline pH region

  A. Decreases
  B. Increases
  C. Remains constant
  D. Varies
  A. Decreases

• Question 196:

  SSC generally occurs below about ________.

  A. 225?F
  B. 200?F
  C. 180?F
  D. 150?F
  C. 180?F

• Question 197:

  The graphitization rate ____________ with increasing temperature

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

• Question 198:

  Naphthenic acid corrosion is a form of high temperature corrosion that occurs primarily in crude and vacuum units and downstream units that process certain fractions that contain naphthenic acid. Which of the following materials is susceptible to naphthenic acid corrosion?

  A. Carbon steel
  B. 300 Series SS
  C. 400 Series SS
  D. All of the above
  D. All of the above

• Question 199:

  (Creep damage can be mitigated by:)

  A. Postweld heat treatment at 1150 癋 (621 癈)
  B. Solution anneal heat treatment
  C. Removing the damaged material
  D. Preheating to 500 癋 (260 癈) during repair welding
  C. Removing the damaged material

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  Comprehensive and Detailed From Exact Extract:

  According to, is a time-dependent, high-temperature damage mechanism that API RP 571 creep damage occurs when materials are exposed to stress at temperatures typically above about 700 癋 (370 癈) for extended periods. Creep damage results in void formation, microcracking, grain boundary separation, and eventual rupture.

  Once creep damage has occurred, it is considered irreversible metallurgical degradation. API RP 571 clearly states that heat treatments cannot restore creep life because the material's microstructure has already been permanently damaged.

  Option A (PWHT at 1150 癋) may relieve residual stresses but does not heal creep voids or microcracks.

  Option B (Solution annealing) is applicable to certain stainless steels but is not effective for reversing creep damage, particularly in low-alloy and Cr-Mo steels.

  Option D (Preheating during welding) helps prevent hydrogen-related cracking but has no effect on existing creep damage.

  API RP 571 emphasizes that the only effective mitigation for creep damage is to remove the affected material and replace it with sound material, or to retire the component if damage is widespread. Fitness-for-service assessments (API 579-1/ASME FFS-1) may be used to evaluate remaining life, but mitigation requires material removal.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Creep and Stress Rupture Damage

  API Corrosion and Materials Study Guide

• Question 200:

  A 6", A106 Gr B, flanged line carrying caustic wash water at 200?F has signs of atmospheric corrosion. Which of the following may have help accelerate the corrosion?

  A. Sulfides
  B. Fly ash
  C. Caustic
  D. None of the above
  B. Fly ash