API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 541:

  With 885?F embrittlement, increasing amounts of ________ increase susceptibility to damage when operating in the high temperature range of concern.

  A. Chromium
  B. Hardness
  C. Ferrite
  D. Hydrogen
  C. Ferrite

• Question 542:

  (Which of the following can be used to confirm 885 癋 (475 癈) embrittlement?)

  A. Metallographic testing
  B. Ductility testing
  C. Magnetic particle testing
  D. Bend or impact testing
  D. Bend or impact testing

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  Comprehensive and Detailed From Exact Extract: Per, primarily affects carbon and low-alloy steels, causing a API RP 571 885 癋 (475 癈) embrittlement loss of toughness without obvious microstructural changes visible by routine metallography. Because the damage mechanism manifests as a shift in ductile-to-brittle transition temperature (DBTT), confirmation requires mechanical property testing, not surface or volumetric NDE. Impact testing (Charpy V-notch) and bend testing are specifically cited as effective methods to demonstrate the loss of toughness and increased brittleness associated with 475 癈 embrittlement. Why the other options are incorrect: Metallography often shows little or no visible change. Magnetic particle testing only detects surface-breaking flaws. Ductility testing alone is not as definitive as impact toughness testing. Referenced Documents (Study Basis): API RP 571 - Section on 885 癋 (475 癈) Embrittlement API Corrosion and Materials Study Guide

• Question 543:

  What is the chemical symbol for butane of butylenes?

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

• Question 544:

  Carburization can be confirmed by substantial increases in _______ and loss of __________.

  A. Hardness
  B. Tensile Strength
  C. Ductility
  D. A and B
  E. A and C
  E. A and C

• Question 545:

  Sigma phase embrittlement can occur in which of the following piping materials operating at temperatures of 1000癋 to 1750癋 (538癈 to 954癈)?

  A. 300 series stainless steel
  B. 400 series stainless steel (12Cr)
  C. Monel 400
  D. 5% chrome
  A. 300 series stainless steel

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  As per API RP 571 Section 5.3.2.2 (Sigma Phase Embrittlement):

  "Sigma phase embrittlement occurs in austenitic stainless steels (like 300 series) and duplex stainless steels exposed to 1000癋 to 1800癋 (540癈 to 980癈)... This embrittlement results in a significant loss of toughness and ductility." Sigma phase is not a concern in Monel (nickel-copper alloy) or 5Cr steels. 400 series are ferritic and not typically affected by sigma phase. Hence, Option A (300 series stainless steel) is correct.

• Question 546:

  Major factors affecting sulfidation are alloy composition, temperature and ________.

  A. Time
  B. Stress
  C. Concentration of hydrogen
  D. Concentration of sulfur
  D. Concentration of sulfur

• Question 547:

  Typically, surface decarburization will have what effect on steel components in high temperature service?

  A. Accelerate stress cracking potential
  B. Cause failure by lowering strength
  C. Accelerate oxidation and sulfidation corrosion
  D. Normally no detrimental effect
  B. Cause failure by lowering strength

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  Comprehensive and Detailed From Exact Extract:

  According to API RP 571, surface decarburization is a metallurgical degradation mechanism that occurs when carbon is removed from the surface layers of steel due to exposure to oxidizing environments at elevated temperatures. This results in a carbon-depleted surface layer. Carbon is a primary strengthening element in carbon and low-alloy steels. When carbon is lost from the surface:

  Hardness and tensile strength are reduced

  Creep resistance and load-carrying capability decrease

  The component becomes more susceptible to plastic deformation and failure under stress

  API RP 571 states that decarburization leads to loss of mechanical strength, especially critical in high-temperature service, where components already operate close to material limits.

  Why the other options are incorrect:

  Option A: Stress cracking is not the primary effect; loss of strength is.

  Option C: Decarburization does not directly accelerate oxidation or sulfidation, although both may coexist.

  Option D: This is incorrect; decarburization is considered detrimental in high-temperature applications.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Decarburization and Metal Dusting API Corrosion and Materials Study Guide

• Question 548:

  What is the minimum pH value where chloride stress corrosion cracking begins to occur?

  A. 2
  B. 4
  C. 7
  D. 10
  A. 2

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  Comprehensive and Detailed From Exact Extract: API RP 571 chloride stress corrosion cracking (Cl-SCC) of austenitic stainless steels is strongly influenced by low pH environments in the presence of chlorides, tensile stress, and elevated temperature.

  API RP 571 identifies that: Chloride SCC can initiate at very low pH levels pH values near 2 represent a threshold where aggressive chloride attack and cracking become possible

  Increasing acidity dramatically increases SCC susceptibility Therefore, pH = 2 is the lowest and most critical value listed where chloride SCC can begin.

  Referenced Documents (Study Basis): API RP 571 - Section on Chloride Stress Corrosion Cracking

• Question 549:

  Which of the following damage mechanisms is related to steel hardness?

  A. Stress-oriented hydrogen-induced cracking
  B. Sulfide stress corrosion cracking
  C. Hydrogen-induced cracking
  D. Hydrogen blistering
  B. Sulfide stress corrosion cracking

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  API RP 571 details that:

  "Sulfide Stress Cracking (SSC) susceptibility increases significantly with increased hardness of the steel."

  "NACE MR0175/ISO 15156 provides hardness limits for carbon and low-alloy steels to avoid SSC in sour environments. These are typically limited to 22 HRC or 248 Brinell."

  "High hardness promotes crack initiation under tensile stress in sour environments (i.e., containing H#S)."

  API RP 571, Section 4.2.2.1 - Sulfide Stress Corrosion Cracking)

  While hydrogen-induced cracking (HIC) and blistering are related to hydrogen charging, SSC is the only mechanism directly and critically impacted by hardness, making option B correct.

• Question 550:

  At elevated temperatures, dissimilar weld metal cracking is aggravated by the diffusion of carbon out of the weld metal and into the base metal. The temperature at which carbon diffusion becomes a concern is above ________.

  A. 700?F
  B. 750?F
  C. 800?F
  D. 900?F
  C. 800?F