[Apr 01, 2026] API-571 Test Engine files, API-571 Dumps PDF
Latest API API-571 PDF and Dumps (2026) Free Exam Questions Answers
NEW QUESTION # 35
Boiler water condensate corrosion is caused primarily by:
- A. Carbon dioxide and oxygen
- B. High pH from water treatment problems
- C. Dissolved iron oxides
- D. Sodium sulfites or hydrazines
Answer: A
Explanation:
According to API RP 571, in the section on Boiler Water Condensate Corrosion:
"The major contributors to condensate corrosion are dissolved CO# and O#. Carbon dioxide forms carbonic acid in the presence of water, lowering pH and causing generalized corrosion."
"Oxygen causes pitting and localized corrosion unless chemically treated." Thus, option B (Carbon dioxide and oxygen) is the primary root cause and the correct answer.
NEW QUESTION # 36
Temper embrittlement _________ be prevented if the material contains critical levels of the embrittling impurity elements and is exposed in the embrittling range.
- A. Will
- B. None of the above
- C. Can
- D. Cannot
Answer: D
NEW QUESTION # 37
Metal dusting is preceded by ________ and is characterized by rapid metal wastage.
- A. Decarburization
- B. Carburization
- C. None of the above
- D. Graphitization
Answer: B
NEW QUESTION # 38
_________ is the main concern during start-up, shutdown and/or hydro testing for equipment/piping operating at elevated temperatures. This event can also occur in an auto refrigeration event in units processing light hydrocarbons.
- A. Stress fracture
- B. Spheroidization
- C. Carburization
- D. Brittle fracture
Answer: D
NEW QUESTION # 39
The likelihood of brittle fracture is best lessened by:
- A. Using carbon or low-alloy steels
- B. Using thicker construction materials to lower the resulting stress
- C. Frequent inspection of the piping or equipment involved
- D. Postweld heat treatment (PWHT)
Answer: D
Explanation:
From API RP 571, brittle fracture prevention measures include:
"Postweld Heat Treatment (PWHT) reduces residual stresses in the heat affected zone and base metal, thus lowering susceptibility to brittle fracture."
"PWHT is particularly effective when applied to pressure-containing components fabricated from carbon steel or low-alloy steel that will experience low-temperature service." (Reference: API RP 571, Section 4.2.1.2 - Brittle Fracture) Therefore, while other measures may reduce stress or detect flaws, PWHT directly targets one of the root causes: residual stress. Thus, option D is the best prevention method.
NEW QUESTION # 40
Carbonate SCC may easily be mistaken for SSC or SOHIC; however, the carbonate cracks are usually
________ the toe of the weld and have multiple parallel cracks.
- A. Diagonal to
- B. Perpendicular to
- C. Further from
- D. Closer to
Answer: C
NEW QUESTION # 41
All ________ based materials and low alloy materials, 300 Series SS and 400 Series SS are susceptible to Sulfidation.
- A. Chromium
- B. Carbon
- C. Steel
- D. Iron
Answer: D
NEW QUESTION # 42
For a specific material, HTHA is dependent on temperature, hydrogen partial pressure, time and _________.
- A. Alloy composition
- B. Velocity
- C. Pressure
- D. Stress
Answer: D
NEW QUESTION # 43
When connected to a more anodic material, titanium may suffer severe __________.
- A. Hydriding
- B. Notch toughness
- C. Stress
- D. Corrosion
Answer: A
NEW QUESTION # 44
The creep threshold temperature for 1 1/4, 2 1/4, 5 and 9 Cr is ________.
- A. 700(o) F
- B. 600(o) F
- C. 800(o) F
- D. 1000(o) F
Answer: C
NEW QUESTION # 45
Annealed steels are more resistant to Spheroidization than normalized steels. _________ grained steels are more resistant than ______ grained steels.
- A. PWHT, Non-PWHT
- B. Course, Fine
- C. Fine, Course
- D. Non-PWHT, PWHT
Answer: B
NEW QUESTION # 46
________ is a form of carbon that may promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures.
- A. Carbonic acid
- B. Crude oil
- C. None of the above
- D. Coke
Answer: D
NEW QUESTION # 47
_________ acid is most often used as a catalyst in polymerization units.
- A. Naphthenic
- B. Polythionic
- C. Phosphoric
- D. Sulfuric
Answer: C
NEW QUESTION # 48
HTHA is dependant on temperature, hydrogen partial pressure, time and _________.
- A. Pressure
- B. Stress
- C. Yield
- D. Tensile strength
Answer: B
NEW QUESTION # 49
Which of the following materials is least affected by brittle fracture?
- A. 300 series stainless steel
- B. Carbon steel
- C. 400 series stainless steel
- D. All stainless steels
- E. Chromes
Answer: A
NEW QUESTION # 50
How can temper embrittlement be prevented if a material contains critical levels of the appropriate impurity elements and is exposed in the embrittling temperature range?
- A. Postweld heat treatment (PWHT) of repairs
- B. Specification of Charpy V-notch impact test
- C. Embrittlement cannot be prevented
- D. Use of a controlled pressurization sequence
Answer: B
Explanation:
API RP 571 provides the following guidance regarding temper embrittlement:
"For materials that contain impurity levels which make them susceptible to temper embrittlement, the most effective preventive measure is to specify low FATT or Charpy impact energy requirements."
"These requirements ensure the material retains adequate toughness even if embrittlement occurs."
"While temper embrittlement itself cannot always be fully prevented during long-term exposure to temperatures between 650°F and 1070°F (343°C-577°C), its effects can be identified and mitigated through impact testing criteria." Therefore, option C is correct. Specification of Charpy V-notch testing ensures material selection accounts for embrittlement susceptibility and maintains service integrity.
NEW QUESTION # 51
300 series stainless steel heater tubes in an oil-burning furnace in the hydrocracker began to leak and the furnace was brought down. What was the probable cause of the cracking?
- A. Polythionic acid stress corrosion
- B. Stress oriented hydrogen induced cracking
- C. Chloride stress corrosion
- D. Amine stress corrosion
Answer: A
NEW QUESTION # 52
(A section of vacuum bottom outlet piping is being replaced because of naphthenic acid corrosion (NAC).
Which of the following potential replacement materials would be most resistant to NAC?)
- A. 9 Cr-1 Mo steel
- B. 317 stainless steel
- C. 321 stainless steel
- D. Titanium
Answer: D
Explanation:
Comprehensive and Detailed Explanation From Exact Extract:
Naphthenic Acid Corrosion (NAC) occurs in high-temperature refinery streams (typically 450-750 °F / 230-
400 °C) containing organic acids. According to API RP 571, NAC is particularly aggressive toward carbon steels and low-alloy steels, and resistance improves with increasing chromium and molybdenum content, but is best with titanium.
Titanium exhibits exceptional resistance to NAC due to the formation of a stable, protective oxide film that is not attacked by naphthenic acids. API RP 571 identifies titanium as one of the most resistant materials available for severe NAC environments.
Why the other options are less suitable:
Option B (9 Cr-1 Mo steel) has limited resistance and is still susceptible at higher TAN and velocities.
Option C (317 stainless steel) offers improved resistance but can still experience attack under severe NAC conditions.
Option D (321 stainless steel) has lower molybdenum content than 317 SS, making it less resistant.
API RP 571 explicitly notes that titanium provides superior resistance compared to stainless steels and Cr-Mo alloys in NAC service.
Referenced Documents (Study Basis):
API RP 571 - Section on Naphthenic Acid Corrosion
API Corrosion and Materials Selection Study Guide
NEW QUESTION # 53
Blistering, HIC, SOHIC and SSC damage can occur wherever there is a ____________ environment.
- A. Hydrogen
- B. Sulfur
- C. Aqueous
- D. Wet H²S
Answer: D
NEW QUESTION # 54
Steel hardness, __________ and stress are critical factors in causing hydrogen stress cracking.
- A. Alloy composition
- B. Temperature
- C. Strength
- D. None of the above
Answer: C
NEW QUESTION # 55
Which of the following alkanolamine systems is the least aggressive in causing amine corrosion?
- A. Methyldiethanolamine (MDEA)
- B. Diglycolamine (DGA)
- C. Monoethanolamine (MEA)
- D. Diethanolamine (DEA)
Answer: A
NEW QUESTION # 56
SCC usually occurs at pH values above two (2). SCC tendency __________ toward the alkaline pH region
- A. Increases
- B. Stabilizes
- C. None of the above
- D. Decreases
Answer: D
NEW QUESTION # 57
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