API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 561:

  Corrosion under insulation becomes more severe at metal temperatures between ________ and ________, where water is less likely to vaporize and insulation stays wet longer.

  A. 100?C, 121?C
  B. 92?C, 116?C
  C. 114?C, 132?C
  D. None of the above
  A. 100?C, 121?C

• Question 562:

  ___________ is the result of cyclic stresses caused by variations in temperature.

  A. Cyclic cracking
  B. Stress cracking
  C. Stress fatigue
  D. Thermal fatigue
  D. Thermal fatigue

• Question 563:

  The most important alloying element for prevention of high-temperature hydrogen attack is:

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

  ---

  According to API RP 941, and also noted in RP 571: "Nickel significantly improves resistance to HTHA (High Temperature Hydrogen Attack) by stabilizing austenitic phases and reducing carbide decomposition." Hence, option C is correct.

• Question 564:

  Type 304L SS is satisfactory for phosphoric acid concentration of 100% up to about _________. Type 321 is required from there to 225?F.

  A. 140?F
  B. 150?F
  C. 100?F
  D. 120?F
  D. 120?F

• Question 565:

  Fatigue cracks usually initiate on the surface at notches or __________ under cyclic loading.

  A. Branches
  B. Laterals
  C. Stress concentrations
  D. Grinding marks
  C. Stress concentrations

• Question 566:

  Spheroidization and graphitization are competing mechanisms that occur at overlapping temperature ranges. Spheroidization tends to occur preferentially above _______ while graphitization predominates below this temperature.

  A. 1000?F
  B. 1025?F
  C. 1050?F
  D. 1100?F
  B. 1025?F

• Question 567:

  A minimum of ________ to ______ molybdenum is needed in an alloy to resist naphthenic acid corrosion.

  A. 2%, 3%
  B. 1 ?%, 2 ?%
  C. 2%, 2%, 2 ?%2 ?%
  D. 1%, 21%, 2%%
  C. 2%, 2%, 2 ?%2 ?%

• Question 568:

  What steel alloy is no longer recommended for services susceptible to HTHA?

  A. Mn-0.5 Mo steel
  B. 1.25 Cr-0.5 Mo steel
  C. 1 Cr-0.5 Mo steel
  D. C-0.5 Mo steel
  C. 1 Cr-0.5 Mo steel

  ---

  Comprehensive and Detailed From Exact Extract: According to API RP 571 and API RP 941 (Nelson Curves) 1 Cr-0.5 Mo steel is no longer recommended for services susceptible to High-Temperature Hydrogen Attack (HTHA).

  API RP 941 documents industry experience showing that 1 Cr-0.5 Mo steels have suffered HTHA damage below previously assumed safe operating limits, due to insufficient carbide stability. As a result, this material has been removed from the Nelson Curves as an acceptable choice for new construction in hydrogen service.

  By contrast: Mn-0.5 Mo, C-0.5 Mo, and 1.25 Cr-0.5 Mo steels retain higher resistance due to more stable carbide structures.

  Referenced Documents (Study Basis):

  API RP 571 - Section on High-Temperature Hydrogen Attack

  API RP 941 - Updated Nelson Curves and Material Recommendations

• Question 569:

  With steam blanketing, failure occurs as a result of _________ in the tube from the internal steam pressure at the elevated temperature.

  A. Stress risers
  B. Velocity
  C. Hoop stress
  D. Tensile strength
  C. Hoop stress

• Question 570:

  ________ is a form of carbon that may promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures.

  A. Carbonic acid
  B. Coke
  C. Crude oil
  D. None of the above
  B. Coke