API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 291:

  Amine cracking is a form of ________ stress corrosion cracking.

  A. Hydrogen
  B. Caustic
  C. Polythionic
  D. Alkaline
  D. Alkaline

• Question 292:

  Cavitation is best prevented by avoiding conditions that allow the absolute pressure to fall below the ___________ of the liquid or by changing the material properties.

  A. Minimum pressure
  B. Pressure/vapor ratio
  C. Maximum pressure
  D. Vapor pressure
  D. Vapor pressure

• Question 293:

  Ferritic stainless steels are usually not used in __________ applications.

  A. Non-pressure boundary
  B. Pressure boundary
  C. High temperature
  D. Low temperature
  B. Pressure boundary

• Question 294:

  With HF acid corrosion, oxygen contamination _________ the corrosion rate of carbon steel and promotes accelerated corrosion and SCC of Alloy 400.

  A. Increases
  B. Decreases
  C. Maintains
  D. Eliminates
  A. Increases

• Question 295:

  ______ is similar to HIC but is a potentially more damaging form of cracking which appears as arrays of cracks stacked on top of each other. The result is a through thickness crack that is perpendicular to the surface and is driven by high levels of stress.

  A. MIC
  B. SOHIC
  C. Sulfuric SCC
  D. None of the above
  B. SOHIC

• Question 296:

  Steel hardness and strength are critical factors for what type of damage mechanism?

  A. Carbonate corrosion stress cracking
  B. Polythionic acid cracking
  C. Hydrogen stress cracking--HF
  D. Amine stress corrosion cracking
  C. Hydrogen stress cracking--HF

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  API RP 571 emphasizes under Hydrogen Stress Cracking - Hydrofluoric Acid (HF) :

  "Cracking in carbon steel is influenced by high hardness and tensile stress in the presence of wet HF acid."

  "Controlling weld and heat-affected zone hardness to below 200 BHN is a key mitigation measure, as

  higher hardness significantly increases susceptibility."

  Steel hardness and strength are thus critical for cracking in HF environments, making option C correct.

• Question 297:

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

  A. Temperature
  B. Material properties
  C. Pressure
  D. Velocity
  B. Material properties

• Question 298:

  _________ significantly increases the probability and severity of blistering, HIC and SOHIC.

  A. Hydrogen
  B. Oxygen
  C. Cyanide
  D. Caustic
  C. Cyanide

• Question 299:

  Which of the following weldments is most susceptible to dissimilar metal cracking when operating at high temperatures?

  A. Carbon steel to Inconel 625
  B. Carbon steel to Monel 400
  C. Carbon steel to Incoloy 800
  D. Carbon steel to 316 stainless steel
  D. Carbon steel to 316 stainless steel

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  Dissimilar Metal Cracking (DMC) is a form of high-temperature cracking that frequently occurs in weld joints between carbon steel and austenitic stainless steel (such as Type 316 SS) due to differences in thermal expansion coefficients and mechanical properties.

  From API RP 571 Section 5.2.3.1 (Dissimilar Metal Weld Cracking):

  "Cracking frequently occurs in weld joints between ferritic and austenitic materials such as carbon steel to 300 series stainless steels due to thermal expansion mismatch during high temperature operation."

  Therefore, Option D (Carbon steel to 316 stainless steel) is the most susceptible combination and the correct answer.

• Question 300:

  In a wet H2S-type environment, what fluid material will significantly increase the probability of blistering?

  A. Polythionic acid
  B. Cyanides
  C. Carbonates
  D. Amines
  B. Cyanides

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  According to API RP 571 Section 5.1.2.1 (Hydrogen-Induced Cracking) and Publ 939-A, blistering in carbon and low alloy steels exposed to wet H2S environments can be exacerbated by the presence of cyanides . These accelerate hydrogen entry into steel, increasing the chance of hydrogen blistering. API RP 571 states:

  "HIC and blistering are forms of hydrogen damage that occur in wet H2S environments. The presence of cyanides can significantly increase hydrogen entry and the risk of blistering."

  Publ 939-A (Research on Cracking in Wet H2S Service) also notes:

  "Cyanides act as catalytic agents in hydrogen charging, which promotes internal pressure build-up and

  increases blistering."

  Thus, cyanides (Option B) are the most critical in enhancing blistering in H2S environments.