API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 521:

  Microbiologically induced corrosion is largely independent of the:

  A. Water content of the process
  B. Presence of hydrogen sulfide
  C. pH of the fluid
  D. Velocity of the flow stream
  D. Velocity of the flow stream

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  From API RP 571 on Microbiologically Influenced Corrosion (MIC):

  "MIC depends on the presence of water, nutrients, and specific microbial species such as SRB (sulfate-reducing bacteria)."

  "While flow velocity may influence deposition and oxygen content, MIC can occur in both stagnant and flowing systems. Hence, it's not strongly dependent on velocity."

  Thus, option D is correct -- MIC is largely independent of flow velocity.

• Question 522:

  The rate of spheroidization is affected by:

  A. temperature and pressure.
  B. type of steel and H# partial pressure.
  C. exposure time and stress.
  D. temperature and microstructure.
  D. temperature and microstructure.

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  According to API RP 571 Section 5.3.2.3 (Spheroidization): "Spheroidization is the transformation of the microstructure of carbon and low alloy steels when exposed to elevated temperatures for long durations. The rate of spheroidization depends on temperature, prior microstructure, and exposure time... The microstructure becomes less effective at carrying loads, and strength is reduced." Key influencing factors for the rate of spheroidization are: Temperature (higher accelerates the process), Microstructure (initial phase distribution and morphology). Pressure and hydrogen partial pressure are not relevant for this transformation, nor is stress a primary driver. Therefore, Option D (temperature and microstructure) is correct.

• Question 523:

  Caustic embrittlement cracking can be effectively prevented by means of PWHT at a temperature of _______.

  A. 1100?F
  B. 1150?F
  C. 1200?F
  D. 1250?F
  B. 1150?F

• Question 524:

  Sigma phase in welds can be minimized by controlling ferrite in the range of _________ for Type 347 SS.

  A. 3%-5%
  B. 5%-7%
  C. 7%-9%
  D. 5%-9%
  D. 5%-9%

• Question 525:

  Which of the following are affected by sulfidation?

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

• Question 526:

  Which of these materials are not susceptible to PASCC?

  A. Carbon steel
  B. 300 Series SS
  C. 400 Series SS
  D. Both A and C
  D. Both A and C

• Question 527:

  What alloy element most improves naphthenic acid corrosion (NAC) resistance?

  A. Molybdenum
  B. Chromium
  C. Niobium
  D. Nickel
  A. Molybdenum

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  API RP 571, Naphthenic Acid Corrosion:

  "Molybdenum significantly improves resistance to naphthenic acid attack. Alloys such as 317, 316Mo, and Alloy 20 are used in severe NAC environments due to higher Mo content."

  "Chromium and nickel play secondary roles; molybdenum is the key element."

• Question 528:

  Exposure to high solution strength caustic can result in general corrosion or high corrosion rates above ________.

  A. 175?F
  B. 150?F
  C. 125?F
  D. 100?F
  B. 150?F

• Question 529:

  Polythionic acid stress corrosion cracking (PTASCC) can be detected by:

  A. Hardness measurements
  B. Magnetic particle testing
  C. Liquid penetrant testing
  D. Ultrasonic thickness measurements
  C. Liquid penetrant testing

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  From API RP 571 Section 5.1.2.5 (Polythionic Acid Stress Corrosion Cracking): "PTASCC typically occurs on the surface of stainless steels that have been sensitized. Since cracks are open to the surface, liquid penetrant testing (PT) is the most effective detection method." Magnetic particle testing is ineffective for non-magnetic materials like austenitic stainless steels. UT is less effective for fine surface-connected cracks. Hardness testing is unrelated to detecting cracking. Thus, Option C (Liquid penetrant testing) is the correct and preferred method for detecting PTASCC.

• Question 530:

  Hardness is primarily an issue with SSC. Typical low strength carbon steels should be controlled to produce weld hardness less than ________.

  A. 225 BHN
  B. 237 BHN
  C. 200 BHN
  D. 240 BHN
  C. 200 BHN