API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 71:

  Resistance to oxidation of steel is best provided by alloying with:

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

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  Comprehensive and Detailed From Exact Extract: According to, oxidation API RP 571 chromium is the most effective alloying element for improving resistance in steels. Chromium: Forms a stable, adherent chromium oxide (Cr#O#) scale Greatly reduces oxidation rates at elevated temperatures Is the basis for oxidation-resistant alloys and stainless steels Other alloying elements may provide secondary benefits, but chromium is the primary contributor to oxidation resistance.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Oxidation and High-Temperature Corrosion

• Question 72:

  Ammonium chloride salts may be whitish, greenish or _________.

  A. Reddish
  B. Brownish
  C. Yellowish
  D. Bluish
  B. Brownish

• Question 73:

  Refer to the following table: Corroded End -- Anodic (More Active) Magnesium Magnesium alloys Zinc Aluminum Aluminum alloys Steel Cast iron Type 410 SS (active state) Ni-Resist Type 304 SS (active state) Type 316 SS (active state) Lead Tin Nickel Brass Copper Bronze Copper-Nickel Monel Nickel (passive state) Type 410 SS (passive state) Type 304 SS (passive state) Type 316 SS (passive state) Titanium Graphite Gold Platinum Protected End -- Cathodic (More Noble) Which of the following metal combinations is most likely to experience galvanic corrosion in brackish water or seawater?

  A. Brass coupled to nickel
  B. Aluminum coupled to steel
  C. Cast iron coupled to Ni-resist
  D. Steel coupled to nickel
  B. Aluminum coupled to steel

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  Galvanic corrosion occurs when two dissimilar metals are electrically connected in the presence of an electrolyte such as brackish water or seawater. The rate and severity of galvanic corrosion depend on: The relative position of the metals on the galvanic series (potential difference) Area ratio between anode and cathode Conductivity of the electrolyte API RP 571 explains:

  "The more active (anodic) metal in the galvanic couple corrodes preferentially. The more noble (cathodic) metal is protected." "The greater the difference in potential between the two metals, the more aggressive the galvanic reaction."

  "Aluminum is highly anodic compared to steel. In seawater or brackish conditions, aluminum will corrode rapidly when electrically coupled to steel, especially if the aluminum surface area is small

  relative to the steel."

  API RP 571, Section 4.3.5.1 - Galvanic Corrosion)

  Referring to the galvanic series presented in your table:

  Aluminum is much higher (more anodic) than steel.

  This makes aluminum the sacrificial metal in such a pair.

  This is not the case for brass-to-nickel or cast iron-to-Ni-Resist, which are much closer together on the galvanic scale.

  Therefore, among all the listed pairs, Aluminum coupled to Steel creates the most significant galvanic potential difference and is most likely to result in galvanic corrosion in brackish or seawater service.

• Question 74:

  The sudden rapid fracture under stress (residual or applied) where the material exhibits little or no evidence of ductility or plastic deformation is called _________.

  A. 885?F Embrittlement
  B. Temper Embrittlement
  C. Stress Corrosion Cracking
  D. Brittle Fracture
  D. Brittle Fracture

• Question 75:

  Hydrogen blisters may form at many different depths from the surface of the steel, in the middle of the plate or near a weld. In some cases, neighboring or adjacent blisters that are at slightly different depths (planes) may develop cracks that link them together. Interconnecting cracks between the blisters often have a __________ appearance.

  A. Crescent
  B. Eyebrow
  C. Step like
  D. Jagged
  C. Step like

• Question 76:

  Which of the following is not a critical factor that contributes to a brittle fracture?

  A. The material's fracture toughness
  B. Maximum operating temperature
  C. Stress concentration at a flaw
  D. Magnitude of the residual stresses
  B. Maximum operating temperature

• Question 77:

  Susceptibility of an alloy to sulfidation is determined by its ability to form protective _________.

  A. Oxide scales
  B. Sulfide scales
  C. Carbide scales
  D. None of the above
  B. Sulfide scales

• Question 78:

  A form of thermal cracking, __________, can occur when high and nonuniform thermal stresses develop over a relatively short period of time in a piece of equipment due to differential expansion and contraction.

  A. Thermal expansion
  B. Thermal stress
  C. Thermal shock
  D. Linear expansion
  C. Thermal shock

• Question 79:

  Mechanical fatigue is caused by:

  A. Cyclic stresses occurring over a long period of time.
  B. Higher than average stresses at high temperatures.
  C. Constant stresses occurring at low temperatures.
  D. Cyclic operating conditions of bird poop then rain, bird poop then rain, etc.
  A. Cyclic stresses occurring over a long period of time.

• Question 80:

  Which material does not have an endurance limit?

  A. Non-normalized carbon steel
  B. Normalized carbon steel
  C. Stainless steel
  D. Titanium
  C. Stainless steel