API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 421:

  Which of the following is a critical factor for chloride stress corrosion cracking?

  A. Presence of nickel content less than 8%
  B. Presence of oxygen
  C. Presence of nickel content higher than 35%
  D. Use in an alkaline pH region
  B. Presence of oxygen

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  According to API RP 571, in the section on "Chloride Stress Corrosion Cracking (Cl-SCC)", several critical factors are outlined that contribute to the initiation and propagation of this mechanism. The document states:

  "Critical factors include the presence of chlorides (even at ppm levels), oxygen, elevated temperatures, tensile stress, and susceptible materials such as austenitic stainless steels and some nickel alloys."

  "Oxygen is an accelerant and promotes pitting that can lead to SCC initiation."

  API RP 571, 3rd Edition, Section 4.2.2.2)

  Therefore, the presence of oxygen is a well-documented critical factor in Cl-SCC. It acts in conjunction with chlorides to initiate localized pitting, which then progresses into cracking. Hence, option B is the correct choice.

• Question 422:

  General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activity is called _______.

  A. Cooling water corrosion
  B. Oxidation
  C. MIC
  D. None of the above
  A. Cooling water corrosion

• Question 423:

  With CUI, corrosion rates __________ with increasing metal temperatures up to the point where the water evaporates quickly.

  A. Decrease
  B. Increase
  C. Stay the same
  D. None of the above
  B. Increase

• Question 424:

  Short-term stress rupture is a/an:

  A. failure caused by repeated cycling from elevated temperature, typically characterized by through-wall oxide filled ruptures with little bulging.
  B. elevated temperature failure caused by localized overheating, typically characterized by bulging and thinning.
  C. elevated temperature failure caused by diffusion of hydrogen into the material, typically characterized by blistering and cracking.
  D. cracking failure caused by sulfides formed at elevated temperature that convert to acids on exposure to moisture and oxygen.
  B. elevated temperature failure caused by localized overheating, typically characterized by bulging and thinning.

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  From API RP 571 Section 5.3.2.1 (Creep and Stress Rupture):

  "Short-term creep rupture is often associated with localized overheating and results in bulging and thinning, often with a characteristic `fish-mouth' rupture appearance. These failures occur under sustained load in a short time (hours or days), typically in high-temperature service due to a sudden increase in temperature or poor heat distribution." Thus, Option B accurately describes the mechanism and visual indications of short-term stress rupture.

• Question 425:

  Which of the following alkanolamine systems is the least aggressive in causing amine corrosion?

  A. Monoethanolamine (MEA)
  B. Diglycolamine (DGA)
  C. Diethanolamine (DEA)
  D. Methyldiethanolamine (MDEA)
  D. Methyldiethanolamine (MDEA)

• Question 426:

  The dewpoint of hydrochloric acid depends on the concentration of hydrogen chloride. It is typically about _________.

  A. 180?F
  B. 160?F
  C. 130?F
  D. 110?F
  C. 130?F

• Question 427:

  What is the chemical symbol for ethane or ethylene?

  A. C?
  B. C3
  C. C4
  D. CH4
  A. C?

• Question 428:

  Stainless steels have higher coefficients of thermal expansion than carbon steel or low alloy steel or nickel based alloys and are more likely to see _________.

  A. Higher temperatures
  B. Higher stresses
  C. Higher pressure
  D. None of the above
  B. Higher stresses

• Question 429:

  Temper embrittlement is a metallurgical change that is:

  A. Not readily apparent but can be confirmed through tension testing
  B. Readily apparent and can be confirmed through impact testing
  C. Readily apparent and can be confirmed through metallography
  D. Not readily apparent but can be confirmed through impact testing
  D. Not readily apparent but can be confirmed through impact testing

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  API RP 571 describes temper embrittlement as a subtle metallurgical change that reduces impact toughness without obvious macrostructural change: "Temper embrittlement is not readily apparent by visual or standard tensile testing. It is confirmed by Charpy impact testing which measures toughness at low temperatures." "It typically affects Cr-Mo steels exposed to intermediate temperatures (650癋 to 1100癋) for extended times."

  API RP 571, Section 4.2.1.4 - Temper Embrittlement)

  Thus, the condition is not visually or physically apparent, but is confirmed through impact testing, making option D correct.

• Question 430:

  With decarburization, the decarburized layer will be free of carbide phases. Carbon steel will be ______.

  A. Annealed
  B. Quenched
  C. Pure iron
  D. None of the above
  C. Pure iron