API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 271:

  (Which of the following is the appropriate method for monitoring hydrochloric acid corrosion susceptibility in an atmospheric crude unit?)

  A. Ultrasonic thickness measurements of water injection points
  B. Measuring the pH of the water in the boot of the overhead accumulator
  C. Using strategically placed corrosion probes or corrosion coupons
  D. Manual or automatic ultrasonic scanning or profile radiographing of piping, vessels, and exchangers in the system
  B. Measuring the pH of the water in the boot of the overhead accumulator

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  Comprehensive and Detailed From Exact Extract:

  Hydrochloric acid (HCl) corrosion in atmospheric crude units is primarily associated with the overhead system, where chloride salts hydrolyze to form HCl in the presence of condensed water. This damage mechanism is well documented in API RP 571 under "Chloride Stress Corrosion Cracking and Hydrochloric Acid Corrosion". The primary indicator of HCl corrosion risk is the acidity of the condensed water in the overhead system. The overhead accumulator boot water collects condensed water where

  dissolved HCl will be present. Monitoring the pH of this water provides a direct, real-time indication of acid formation and corrosion severity.

  Low pH values (typically below 5.5) indicate active HCl corrosion conditions.

  API RP 571 states that pH monitoring is a key operational control and surveillance tool for managing overhead corrosion.

  Why the other options are incorrect:

  Option A (UT at water injection points) does not address overhead acid formation and is not a susceptibility monitoring method.

  Option C (Corrosion probes or coupons) provide general corrosion rate data, but they do not directly measure HCl formation or acid severity and often respond too slowly for operational control.

  Option D (UT scanning or radiography) is a damage detection method, not a susceptibility or early-warning monitoring technique.

  API RP 571 emphasizes that effective monitoring of HCl corrosion requires controlling and monitoring water chemistry, especially pH in the overhead accumulator boot, to prevent severe localized corrosion and ammonium chloride salt deposition.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Hydrochloric Acid Corrosion in Crude Unit Overhead Systems

  API Corrosion and Materials Study Guides - Atmospheric Crude Unit Overhead Corrosion

• Question 272:

  Alloys with nickel content above _________ are highly resistant to Cl SCC. The greatest susceptibility is 8% to 12% nickel.

  A. 15%
  B. 20%
  C. 30%
  D. 35%
  D. 35%

• Question 273:

  If the BHN is 400-500 it may indicate __________.

  A. Carburization
  B. Hydriding
  C. Temper embrittlement
  D. Caustic embrittlement
  B. Hydriding

• Question 274:

  (Refractory materials can suffer what forms of degradation in service?)

  A. Carburization and fuel ash corrosion
  B. Nitriding and embrittlement
  C. Sulfidation and oxidation
  D. Refractory dusting and checking
  D. Refractory dusting and checking

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  Comprehensive and Detailed From Exact Extract:

  According to, not experience metallic

  API RP 571 refractory materials are non-metallic and therefore do corrosion mechanisms such as carburization, sulfidation, or oxidation. Instead, refractories degrade through: Dusting (loss of material due to chemical or thermal attack) Checking (crack formation caused by thermal cycling and differential expansion) These are the primary and characteristic damage modes of refractories in high-temperature service.

  Referenced Documents (Study Basis):

  API RP 571 - Section on Refractory Degradation

• Question 275:

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

  A. Temperature
  B. Pressure
  C. Velocities
  D. None of the above
  C. Velocities

• Question 276:

  All piping and equipment exposed to HF acid at any concentration with hardness levels above the recommended limit (237 BHN) are subject to _________.

  A. Hydrogen stress cracking
  B. Sulfide stress cracking
  C. Chloride stress cracking
  D. None of the above
  A. Hydrogen stress cracking

• Question 277:

  What standard refers to Risk-Based-Inspection?

  A. RP 581
  B. RP 579
  C. RP 588
  D. RP 568
  A. RP 581

• Question 278:

  Sulfur and chlorine species in fuel will form sulfur dioxide, sulfur trioxide and hydrogen chloride within the combustion products. At low enough temperatures, these gases and the water vapor in the flue gas will condense to form _________ acid.

  A. Hydrochloric
  B. Hydrofluoric
  C. Sulfuric
  D. Both A and C
  D. Both A and C

• Question 279:

  ________ greatly increases the probability and severity of blistering, HIC and SOHIC damage.

  A. Acids
  B. Caustics
  C. Amines
  D. Cyanides
  D. Cyanides

• Question 280:

  Carbonate SCC can occur at relatively low levels of ________ but usually occurs at welds that have not been stressed relieved.

  A. Residual stress
  B. Applied stress
  C. Acid concentration
  D. None of the above
  A. Residual stress