API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 441:

  Thermal fatigue cracks usually propagate _______ to the stress and they are usually dagger-shaped.

  A. Parallel
  B. Diagonal
  C. Transverse
  D. Across
  C. Transverse

• Question 442:

  What arbitrary value of hydrogen sulfide in water is often used as the defining concentration where cracking damage becomes a problem in carbon steel pipe?

  A. 0.05%
  B. 0.5%
  C. 1 ppmw
  D. 50 ppmw
  D. 50 ppmw

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  As per API RP 571 and further clarified in API RP 939-C: "An arbitrary threshold of 50 ppmw H#S in the aqueous phase is often used to define when carbon and low alloy steels become susceptible to cracking damage in wet H#S environments."

  "Below this level, the risk of SSC, HIC, and SOHIC is considered lower, although damage has still occurred

  at lower concentrations depending on stress and metallurgical conditions."

  Therefore, the correct answer is option D (50 ppmw).

• Question 443:

  Oxygen and iron in the wash water injected into reactor effluent can lead to __________ corrosion and fouling.

  A. Increased
  B. Decreased
  C. Substantial
  D. Minimal
  A. Increased

• Question 444:

  High strength, low allow steels such as A193-B7 bolts and compressor parts are susceptible to hydrogen stress cracking. A193-B7M bolts are susceptible if __________.

  A. Exposed
  B. Overtorqued
  C. Double nutted
  D. None of the above
  B. Overtorqued

• Question 445:

  Stainless steels with sigma can normally withstand normal operating stresses but upon cooling to temperatures below _______ may show a complete lack of fracture toughness as measured by a Charpy impact test.

  A. 800?F
  B. 600?F
  C. 500?F
  D. 400?F
  C. 500?F

• Question 446:

  In most cases, brittle fracture occurs only at temperatures _________ the Charpy impact transition temperature.

  A. Above
  B. Below
  C. Around
  D. Inside
  B. Below

• Question 447:

  (Which three residual alloy elements are of most concern when it comes to corrosion of carbon steel in HF Alkylation process units?)

  A. Cr / Mo / Ni
  B. C / Nb / V
  C. Cr / Cu / Ni
  D. Cu / S / V
  C. Cr / Cu / Ni

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  Comprehensive and Detailed From Exact Extract:

  identifies certain residual alloying elements in carbon steel that can HF Alkylation units API RP 571 significantly increase corrosion rates in HF acid service.

  The most detrimental residual elements are:

  Chromium (Cr)

  Copper (Cu)

  Nickel (Ni)

  These elements: Disrupt formation of protective iron fluoride films Increase general and localized corrosion rates Are tightly controlled in carbon steel specifications for HF service

  Referenced Documents (Study Basis): API RP 571 - Section on Hydrofluoric Acid Corrosion

• Question 448:

  Although the loss of toughness from temper embrittlement is not evident at operating temperatures, equipment that is temper embrittled may be susceptible to ________ during start-up and shutdown.

  A. Thermal fatigue
  B. Cyclic stress
  C. Notch toughness
  D. Brittle fracture
  D. Brittle fracture

• Question 449:

  Phosphoric acid corrosion is usually found in ________ areas.

  A. High velocity
  B. Low velocity
  C. High temperature
  D. Low temperature
  B. Low velocity

• Question 450:

  Which of the following will experience the highest oxidation corrosion rate at 1350癋 (732癈)?

  A. Alloy 800H
  B. Type 310 stainless steel
  C. Type 304L stainless steel
  D. 9 Cr low-alloy steel
  D. 9 Cr low-alloy steel

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  API RP 571 under Oxidation:

  "Carbon steels and low alloy steels, such as 9 Cr, have poor oxidation resistance at temperatures above 1000?

  F (540癈), rapidly losing thickness."

  "Stainless steels with higher Cr and Ni content (like 310) have superior oxidation resistance."

  Thus, 9 Cr steel will corrode fastest at 1350癋, making option D correct.