API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 581:

  Corrosion of the anode may be significantly higher ________ to the connection to the cathode, depending on solution conductivity.

  A. Parallel
  B. Adjacent
  C. Diagonally
  D. Perpendicular
  B. Adjacent

• Question 582:

  The accepted way to test for temper embrittlement is ________.

  A. Impact testing
  B. Metallographic
  C. RT
  D. UT Shear wave
  A. Impact testing

• Question 583:

  The most important factors affecting graphitization are the chemistry, stress, temperature and _______.

  A. Velocity
  B. Time at exposure
  C. Pressure
  D. Ductility
  B. Time at exposure

• Question 584:

  Sulfidation is primarily caused by:

  A. Impacting particles.
  B. Sulfur compounds decomposing at higher temperatures.
  C. Sulfur compounds being created in the FCCU (Cat Cracking Unit).
  D. Elemental sulfur collecting in stagnate areas, e.g. dead legs.
  E. Operators failing to adequately control the ph of sulfur streams.
  B. Sulfur compounds decomposing at higher temperatures.

• Question 585:

  In HF service, carbon steel forms a protective _________ scale in dry concentrated acid. Loss of the protective scale through high velocities or turbulence will result in greatly accelerated corrosion rates.

  A. Chloride
  B. Fluoride
  C. Iron sulfide
  D. Iron oxide
  B. Fluoride

• Question 586:

  The most effective means of preventing caustic stress corrosion cracking is:

  A. Postweld heat treatment
  B. Upgrading to 300 series stainless steel
  C. Reducing caustic concentration
  D. Controlling process temperature during steamouts
  A. Postweld heat treatment

  ---

  According to API RP 571, under Caustic Stress Corrosion Cracking (Caustic Embrittlement):

  "Cracking occurs in stressed components exposed to caustic (e.g., sodium hydroxide)."

  "The most effective mitigation strategy is postweld heat treatment (PWHT), which relieves residual stress

  that promotes cracking."

  "Upgrading materials or controlling concentration may help, but do not replace stress relief."

  API RP 571, Section 4.2.2.3 - Caustic SCC)

  Thus, PWHT is the most effective prevention technique, making option A correct.

• Question 587:

  Which of the following damage mechanisms are most closely related because they occur in similar environments?

  A. Carburization and metal dusting
  B. Oxidation and sulfidation
  C. Fuel ash corrosion and flue gas dew-point corrosion
  D. Carbonate corrosion and CO# corrosion
  B. Oxidation and sulfidation

  ---

  According to API RP 571:

  "Oxidation is the reaction of metal and oxygen to form oxides. It generally occurs in high temperature environments with excess oxygen."

  "Sulfidation is a high temperature corrosion mechanism that occurs due to interaction between sulfur-containing compounds and metal surfaces, forming metal sulfides. Like oxidation, sulfidation occurs in environments above 500 癋 (260 癈)."

  "Both oxidation and sulfidation can occur concurrently, particularly in mixed environments of oxygen and sulfur."

  API RP 571, Sections 5.1.1 and 5.1.3 - Oxidation and Sulfidation)

  These two mechanisms are thermally activated and occur in elevated temperature conditions found in heaters, furnaces, and piping systems. Hence, option B is correct.

• Question 588:

  A steam actuated soot blower has condensate in the first steam exiting the soot blower. What type of damage can be expected to be found when the furnace is brought down for maintenance and inspection?

  A. Thermal fatigue
  B. Steam blanketing
  C. Creep
  D. Stress rupture
  A. Thermal fatigue

• Question 589:

  Generally, to minimize corrosion of carbon steel in hydrofluoric acid service, residual elements (Cr, Ni, Cu) should be less than:

  A. 0.15 wt.%
  B. 0.18 wt.%
  C. 0.25 wt.%
  D. 0.35 wt.%
  A. 0.15 wt.%

  ---

  API RP 751, which governs HF alkylation units, specifies:

  "The total residuals of chromium, nickel, and copper in carbon steel used in HF service should be less than 0.15 wt.% to minimize corrosion risk."

  "Higher residuals increase the reactivity and corrosion rate of carbon steel in the presence of HF acid."

  API RP 751, Section 5.3 - Materials Specification for HF Units)

  Therefore, option A is the correct choice.

• Question 590:

  Why are high-cycle fatigue cracks difficult to detect with nondestructive examination (NDE)?

  A. They are usually in 90?corners where inspection is difficult.
  B. Cracks are so tight they are often missed.
  C. Time required for crack growth is not predictable.
  D. They normally start on the I.D. surface.
  B. Cracks are so tight they are often missed.

  ---

  According to, is characterized by very tight, narrow cracks that can API RP 571 high-cycle fatigue (HCF) escape detection using typical NDE methods due to their minimal opening displacement and fine geometry.

  From API RP 571 Section 5.2.1 (Fatigue - High Cycle):

  "The cracks are usually tight and may be difficult to detect using conventional NDE techniques such as PT or MT. UT and RT may also have difficulty identifying these small, tight flaws, especially in early stages of propagation."

  The primary issue in NDE is not the geometry (such as 90?corners) or ID location, but rather the tightness and early-stage subtlety of the cracks which results in reduced detectability. Therefore, option B is correct as it aligns most accurately with API RP 571's detailed characterization of HCF detection challenges.