API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 471:

  Refractory lined equipment should be designed for erosion, thermal shock and __________.

  A. Thermal fatigue
  B. Thermal expansion
  C. Thermal contraction
  D. All of the above
  B. Thermal expansion

• Question 472:

  ____________ are characterized by a localized loss in thickness in the form of pits, grooves, gullies, waves, rounded holes and valleys. These losses often exhibit a directional pattern.

  A. Erosion
  B. Corrosion/Erosion
  C. Environmental corrosion
  D. Both A and B
  D. Both A and B

• Question 473:

  Geometry, stress level, _________ and material properties are the predominate factors in determining the fatigue resistance of a component.

  A. Temperature
  B. Pressure
  C. Velocity
  D. Number of cycles
  D. Number of cycles

• Question 474:

  __________ is a form of stress corrosion cracking normally occurring during shutdowns, startups or during operation when air and moisture are present. Cracking is due to sulfur acids forming from sulfide scale, air and moisture acting on sensitized stainless steel.

  A. Caustic SCC
  B. Chloride SCC
  C. Polythionic acid SCC
  D. None of the above
  C. Polythionic acid SCC

• Question 475:

  ___________ is when oxygen reacts with carbon steel and other alloys at high temperatures converting the metal to oxide scale.

  A. High temperature corrosion
  B. Oxidation
  C. Dealloying
  D. Thermal fatigue
  A. High temperature corrosion

• Question 476:

  Increasing chromium content in the alloy improves resistance to sulfidation. However, there is little improvement with increasing chromium content until about ________ Cr.

  A. 3-5
  B. 5-7
  C. 7-9
  D. 9-12
  C. 7-9

• Question 477:

  Differential expansion in bimetallic welds can give rise to: A. Reheat cracking

  B. Thermal fatigue

  C. Stress corrosion cracking

  D. Galvanic cracking

  Correct Answer. B
  B

  ---

  API RP 571 under Thermal Fatigue highlights:

  "Differential thermal expansion between dissimilar materials (e.g., carbon steel and stainless steel) in welds

  causes high cyclic stresses that can result in thermal fatigue cracking."

  "These stresses typically occur during transient thermal cycling such as startup/shutdown operations."

  API RP 571, Section 4.2.1.5 - Thermal Fatigue)

  Thus, the correct mechanism resulting from differential expansion in bimetallic welds is thermal fatigue, making option B correct.

• Question 478:

  To detect wet insulation that might give rise to corrosion under insulation, which nondestructive examination (NDE) technique would be most useful?

  A. Deep penetrating eddy current
  B. Neutron backscatter
  C. Spectroscopy
  D. Low-intensity X-ray imaging scope
  B. Neutron backscatter

  ---

  According to API RP 571 and API RP 583 (CUI-specific guidance): "Neutron backscatter techniques are effective in detecting moisture within insulation systems, which can

  indicate areas of concern for corrosion under insulation (CUI)."

  "This method provides non-invasive, quick identification of wet insulation without removing cladding."

  API RP 571, Section 4.5.1 - Corrosion Under Insulation and API RP 583 - CUI Detection

  Thus, neutron backscatter is the preferred NDE method for moisture detection, making option B correct.

• Question 479:

  (Grooving in cooling water tubes could be due to:)

  A. Electric resistance welds
  B. Microbiologically induced corrosion
  C. Flow-induced erosion
  D. Underdeposit corrosion
  C. Flow-induced erosion

  ---

  Comprehensive and Detailed From Exact Extract:

  Grooving corrosion in cooling water systems is a well-documented damage mechanism in API RP 571,

  particularly associated with high-velocity flow conditions.

  Flow-induced erosion (also referred to as erosion-corrosion or flow-assisted corrosion) occurs when:

  High fluid velocity removes protective corrosion films

  Local turbulence, elbows, or inlet zones focus mechanical wear

  Soft metals or alloys are exposed to continuous impingement

  This results in smooth, directional grooves or channels aligned with the flow direction, a classic signature described in API RP 571.

  Why the other options are incorrect:

  Option A: ERW defects affect weld seams, not general grooving patterns.

  Option B: MIC typically causes localized pitting, not uniform grooving.

  Option D: Underdeposit corrosion produces irregular pitting beneath deposits, not flow-aligned grooves.

  API RP 571 specifically identifies flow-induced erosion as a primary cause of grooving in cooling water heat exchanger tubes.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Erosion/Erosion-Corrosion

  API Cooling Water System Corrosion Study Guide

• Question 480:

  In design and fabrication, it is advisable to avoid sharp changes in cross section, such as short radius fillets or undercut that can give rise to _________.

  Long-seam welds are particularly susceptible to reheat cracking due to mismatch caused by fit up problems.

  A. Stress concentrations
  B. Cracking
  C. Circumferential stress
  D. All of the above
  A. Stress concentrations