API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 81:

  Amine cracking has been reported down to ambient temperatures with some amines. __________ temperatures and stress levels _______ the likelihood and severity of cracking.

  A. Increasing increases
  B. Increasing, decreases
  C. Decreasing increases
  D. Increasing, reduces
  A. Increasing increases

• Question 82:

  Which of the following statements about high-temperature hydrogen attack is most accurate?

  A. Acoustic emission testing is not a proven method for the detection of high-temperature hydrogen attack damage.
  B. High-temperature hydrogen attack will most often be associated with the formation of surface blisters.
  C. High-temperature hydrogen attack damage is most often limited to welds and heat-affected zones.
  D. 300 series stainless steels are also susceptible to high-temperature hydrogen attack at conditions normally seen in refinery units.
  A. Acoustic emission testing is not a proven method for the detection of high-temperature hydrogen attack damage.

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  API RP 571 on HTHA states:

  "Acoustic emission testing is not currently a proven or reliable method for identifying HTHA in refinery

  components."

  "HTHA typically occurs internally, not as surface blisters, and is not limited to welds. Austenitic (300 series) stainless steels are generally resistant at normal refinery conditions."

  API RP 571, Section 4.2.1.3 - High Temperature Hydrogen Attack) Thus, option A is the most accurate statement.

• Question 83:

  Polythionic acid stress corrosion cracking is:

  A. Identified by transgranular cracking on the process side of equipment and piping.
  B. Found only in low carbon grades of austenitic stainless steel.
  C. Typically localized and may not be evident until a leak appears.
  D. Rarely found in process furnaces.
  C. Typically localized and may not be evident until a leak appears.

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  API RP 571 under Polythionic Acid Stress Corrosion Cracking (PTA SCC) specifies:

  "Cracking is usually intergranular, and often localized, especially in sensitized austenitic stainless steels

  exposed to sulfur-containing environments during shutdown or cleaning."

  "It is not always visible on inspection and may only become evident when a leak occurs."

  API RP 571, Section 4.2.2.5 - PTA SCC)

  Hence, option C is correct as it best describes the detection difficulty and behavior of PTA SCC.

• Question 84:

  Cooling water corrosion of exchanger tubes is typically increased by:

  A. Increasing the passivation layer.
  B. Decreasing the process temperature.
  C. Increasing the oxygen content.
  D. Decreasing the cooling water outlet temperature.
  C. Increasing the oxygen content.

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  According to API RP 571, under the section "Corrosion in Aqueous Environments - Cooling Water Corrosion ", one of the key contributors to corrosion in carbon steel and other materials used in heat exchangers is the presence of dissolved oxygen. API RP 571 states:

  "Oxygen is a primary contributor to corrosion in cooling water systems. Systems open to the atmosphere are typically more corrosive than closed systems due to the continual replenishment of oxygen."

  "Corrosion rates are highest where oxygen concentration is the greatest, especially in systems using untreated or poorly treated water."

  "Carbon steel corrodes in the presence of oxygen and water, forming corrosion products that may or may not adhere to the surface."

  API RP 571, Section 4.3.1.1 - Cooling Water Corrosion)

  Therefore, increasing oxygen content directly increases corrosion activity in exchanger tubes, making option C the correct and documented answer.

• Question 85:

  Which of the following materials is least affected by atmospheric corrosion?

  A. Carbon steel
  B. Chromes
  C. Stainless steels
  D. Copper alloyed with aluminum
  C. Stainless steels

• Question 86:

  Stress relief and stabilization heat treatment of 300 Series SS for maximizing chloride SCC and PASCC resistance can cause ____________ problems, especially in thicker sections.

  A. Thermal fatigue
  B. Reheat cracking
  C. Hydrogen
  D. HIC
  B. Reheat cracking

• Question 87:

  Damage from sigma phase appears in the form of ________.

  A. Corrosion
  B. Hardness
  C. Cracking
  D. Ductility
  C. Cracking

• Question 88:

  In most cases, brittle fracture occurs only at:

  A. High temperatures in areas of high stress concentration
  B. Temperatures below ambient in thick sections
  C. Temperatures below the Charpy impact transition temperature
  D. Temperatures above the Charpy impact transition temperature
  C. Temperatures below the Charpy impact transition temperature

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  API RP 571 provides detailed insights:

  "Brittle fracture generally occurs at low temperatures, specifically below the ductile-to-brittle transition temperature as defined by the Charpy impact test." "Most carbon and low-alloy steels are ductile above their Charpy transition temperature but may fracture suddenly without ductility below it."

  API RP 571, Section 4.2.1.2 - Brittle Fracture)

  Hence, option C is correct and technically accurate based on the material behavior curve.

• Question 89:

  Decarburization results in a __________, which can be confirmed by hardness testing.

  A. Hardness
  B. Softness
  C. Brittleness
  D. Oxidizing
  B. Softness

• Question 90:

  The extent and depth of decarburization is a function of temperature and ______.

  A. Pressure
  B. Material properties
  C. Exposure time
  D. Velocity
  C. Exposure time