Download Offshore Corrosion Assessment Technician Practice Exam and more Exams Technology in PDF only on Docsity!
CAT Technician Practice Exam
Question 1. Which of the following best defines corrosion in offshore structures? A) Oxidation of a metal only in the presence of oxygen B) A chemical reaction that results in the loss of metal material to the environment C) The formation of a protective oxide film that stops further metal loss D) A purely mechanical wear process caused by fluid flow Answer: B Explanation: Corrosion is an electrochemical process that leads to metal loss when the metal reacts with its environment, not merely oxidation in oxygen or mechanical wear. Question 2. In an electrochemical corrosion cell, which component provides the path for electrons? A) Electrolyte B) Anode C) Cathode D) Metallic path Answer: D Explanation: The metallic path (the metal itself) conducts electrons from the anode to the cathode. Question 3. The Gibbs free energy change (ΔG) for a corrosion reaction must be: A) Positive for the reaction to proceed spontaneously B) Negative for the reaction to proceed spontaneously C) Zero for the reaction to proceed spontaneously D) Irrelevant to corrosion spontaneity
CAT Technician Practice Exam
Answer: B Explanation: A negative ΔG indicates a spontaneous reaction, which is required for corrosion to occur. Question 4. Which corrosion type is characterized by small, deep pits that may penetrate the entire wall thickness? A) Uniform corrosion B) Crevice corrosion C) Pitting corrosion D) Intergranular corrosion Answer: C Explanation: Pitting corrosion initiates as localized pits that can grow rapidly and penetrate through metal thickness. Question 5. Crevice corrosion most commonly occurs in which of the following situations? A) Exposed flat surfaces in seawater B) Tight gaps such as under gaskets or bolt heads C) High‑temperature steam lines D) Areas with high tensile stress Answer: B Explanation: Crevice corrosion initiates in stagnant, confined spaces where differential aeration leads to aggressive local chemistry.
CAT Technician Practice Exam
D) Methanogenic archaea Answer: B Explanation: SRB produce hydrogen sulfide, which accelerates corrosion on steel surfaces. Question 9. Erosion‑corrosion is most prevalent in which offshore component? A) Static storage tanks B) Low‑speed subsea pipelines C) High‑velocity flow control valves D) Anchors Answer: C Explanation: High fluid velocities cause mechanical wear combined with chemical attack, leading to erosion‑corrosion. Question 10. The dominant corrosion mechanism in the splash zone of an offshore platform is: A) Uniform corrosion due to constant immersion B) Crevice corrosion caused by trapped water under fittings C) Atmospheric corrosion accelerated by wet‑dry cycles D) Galvanic corrosion with seawater Answer: C Explanation: The splash zone experiences cyclic wet‑dry conditions, promoting atmospheric corrosion.
CAT Technician Practice Exam
Question 11. Which unit is commonly used to express corrosion rate in the United States? A) mm/yr B) μm/h C) mils per year (mpy) D) kg/m²·day Answer: C Explanation: Mils per year (mpy) is a standard unit for corrosion rate in the US. Question 12. Faraday’s law relates corrosion mass loss to: A) Temperature and pressure B) Current density and time C) pH and dissolved oxygen D) Salinity and flow velocity Answer: B Explanation: Faraday’s law states that mass loss is proportional to the charge passed (current × time). Question 13. In a Tafel extrapolation, the corrosion current density (i_corr) is obtained from: A) The intersection of the anodic and cathodic polarization curves B) The slope of the linear region of the cathodic curve only C) The maximum current measured during the scan D) The corrosion potential (E_corr) alone
CAT Technician Practice Exam
Question 16. When designing a SACP system, the “anode consumption rate” is expressed as: A) g A⁻¹ h⁻¹ B) A m² yr⁻¹ C) % of anode mass per year D) V A⁻¹ Answer: C Explanation: Consumption rate is the percentage of anode mass that is consumed annually. Question 17. In impressed current cathodic protection (ICCP), the reference electrode most commonly used for potential measurement is: A) Ag/AgCl B) Cu/CuSO₄ C) Zinc sulfate electrode D) Mercury‑mercurous oxide electrode Answer: A Explanation: Ag/AgCl electrodes provide a stable reference for measuring structure potentials. Question 18. The −850 mV CSE criterion for CP on steel in seawater is based on: A) The open‑circuit potential of pure iron B) The potential at which hydrogen evolution is negligible C) The potential at which uniform corrosion rate falls below 0.1 mpy D) The corrosion potential of stainless steel
CAT Technician Practice Exam
Answer: C Explanation: −850 mV vs. CSE is the target potential to limit corrosion rates to acceptable low values. Question 19. A common cause of ICCP system failure is: A) Over‑protection leading to coating disbondment B) Under‑protection due to insufficient current output C) Anode passivation caused by scale buildup D) All of the above Answer: D Explanation: All listed issues can cause ICCP failure; over‑protection, under‑protection, and anode passivation are typical problems. Question 20. The primary function of a zinc‑rich primer in offshore coating systems is: A) To provide a decorative finish B) To act as a sacrificial barrier delivering cathodic protection until the topcoat is intact C) To increase the surface roughness for better adhesion of subsequent layers D) To prevent biofouling Answer: B Explanation: Zinc‑rich primers release zinc ions that protect the substrate through sacrificial action.
CAT Technician Practice Exam
Answer: C Explanation: CRAs must resist chloride‑induced pitting in seawater; this property is critical for subsea valves. Question 24. Adding a corrosion allowance to a design thickness is intended to: A) Increase the weight of the component for stability B) Compensate for anticipated material loss over the service life C) Reduce fabrication cost D) Improve weldability Answer: B Explanation: Corrosion allowance provides extra thickness to account for expected material loss. Question 25. A common chemical inhibitor used to control oxygen corrosion in closed‑loop seawater systems is: A) Sodium nitrite B) Sodium hydroxide C) Sodium chloride D) Sodium bisulfite Answer: A Explanation: Sodium nitrite acts as an oxygen scavenger, reducing oxidative corrosion. Question 26. Visual inspection of offshore structures primarily aims to:
CAT Technician Practice Exam
A) Determine exact wall thickness values B) Identify obvious signs of corrosion, coating damage, and fouling C) Measure residual stress levels D) Quantify the amount of metal loss Answer: B Explanation: Visual inspection is the first step to detect apparent defects; quantitative measurements require NDT. Question 27. The most effective cleaning method before ultrasonic thickness measurement on a corroded pipe is: A) High‑pressure water jetting B) Solvent wiping only C) Abrasive sandblasting to remove mill scale D) None; cleaning is unnecessary Answer: A Explanation: High‑pressure water jetting removes loose deposits without damaging the surface, ensuring accurate UT readings. Question 28. In ultrasonic testing, a “C‑scan” image provides: A) A single‑point thickness value B) A cross‑sectional profile of the wall thickness along a line C) A planar map of wall thickness over an area D) The velocity of sound in the material
CAT Technician Practice Exam
B) Cu/CuSO₄ (copper sulfate) C) Zinc (Zn) electrode D) Mercury/mercurous sulfate Answer: B Explanation: Cu/CuSO₄ electrodes are commonly used in soil and buried pipeline CP surveys. Question 32. “On‑potential” measurements in CP surveys are taken: A) With the CP system disconnected B) While the CP system is energized C) After the structure has been removed from service D) Only during low tide Answer: B Explanation: On‑potential is measured with the CP system active to assess the protective level. Question 33. A Close Interval Potential Survey (CIPS) is primarily used to: A) Determine coating thickness on a pipeline B) Map the potential distribution along a pipeline at short intervals C) Measure the flow rate of oil in a line D) Locate weld defects Answer: B Explanation: CIPS provides detailed potential readings at frequent intervals to evaluate CP effectiveness.
CAT Technician Practice Exam
Question 34. The holiday detector used on offshore structures typically operates at: A) 1 V low voltage for detecting small pinholes B) 1 kV high voltage for locating larger defects C) Both low‑voltage (≤ 500 V) and high‑voltage (≥ 5 kV) modes D) Only acoustic emission Answer: C Explanation: Holiday detectors have low‑voltage mode for small defects and high‑voltage mode for larger areas. Question 35. Dry film thickness (DFT) of a coating is measured using: A) Ultrasonic thickness gauge B) Magnetic induction gauge C) X‑ray fluorescence (XRF) D) Visual inspection Answer: B Explanation: Magnetic induction gauges are standard for measuring DFT on ferromagnetic substrates. Question 36. In a pull‑off adhesion test, the failure mode that indicates good coating adhesion is: A) Cohesive failure within the coating B) Adhesive failure at the substrate‑coating interface C) Substrate fracture
CAT Technician Practice Exam
Question 39. Statistical analysis of corrosion data to estimate probability of failure is commonly performed using: A) Linear regression only B) Weibull distribution or log‑normal analysis C) Simple averaging of thickness loss D) Fourier transform Answer: B Explanation: Weibull and log‑normal models are standard for reliability and failure probability assessments. Question 40. A typical structure of an offshore inspection report includes all EXCEPT: A) Observation of defects B) Detailed financial accounting of the inspection crew’s expenses C) NDT results and interpretation D) Recommendations for corrective actions Answer: B Explanation: Financial accounting is not part of the technical inspection report. Question 41. The API standard most relevant to offshore pipeline corrosion management is: A) API 650 B) API 570 C) API 1104
CAT Technician Practice Exam
D) API 5L
Answer: B Explanation: API 570 covers inspection, repair, and alteration of piping systems, including corrosion management. Question 42. In Fitness‑for‑Service (FFS) assessment, a component with a wall loss of 30 % of its original thickness is generally considered: A) Safe for continued operation with no restrictions B) To be repaired or replaced depending on remaining strength criteria C) Immediately out of service D) Acceptable only if the material is stainless steel Answer: B Explanation: 30 % loss often triggers evaluation against remaining strength criteria; repair or replacement may be required. Question 43. Risk‑Based Inspection (RBI) programs prioritize inspections based on: A) The age of the equipment only B) The probability of failure and consequence of failure C) The number of previous inspections performed D) The cost of inspection equipment Answer: B Explanation: RBI uses risk = probability × consequence to prioritize inspection resources.
CAT Technician Practice Exam
D) Only the operator’s internal policy Answer: B Explanation: Spent abrasives may be classified as hazardous waste depending on contaminants and must follow relevant regulations. Question 47. Which of the following is a direct environmental impact of offshore corrosion? A) Increased fish population due to metal nutrients B) Release of hydrocarbons from corroded pipelines leading to spills C) Formation of harmless rust particles that settle on the seabed D) None of the above Answer: B Explanation: Corroded pipelines can leak oil or gas, causing environmental contamination. Question 48. The “splash zone” is defined as the area on an offshore structure that: A) Is always submerged under water B) Experiences intermittent wetting and drying due to wave action C) Remains dry at all times D) Is protected by a permanent coating Answer: B Explanation: The splash zone is subject to cyclic wet‑dry conditions, influencing corrosion mechanisms.
CAT Technician Practice Exam
Question 49. Which of the following coating application methods provides the best control over film thickness? A) Brush coating B) Spray coating C) Roll coating D) Dip coating Answer: D Explanation: Dip coating immerses the substrate, allowing precise control of DFT through withdrawal speed and viscosity. Question 50. In the context of offshore corrosion, “galvanic coupling” refers to: A) Two metals electrically connected in seawater, leading to accelerated corrosion of the more anodic metal B) The use of a galvanometer to measure corrosion current C) The application of a galvanic coating on steel D) None of the above Answer: A Explanation: Galvanic coupling occurs when dissimilar metals are electrically connected in an electrolyte, causing the anodic metal to corrode faster. Question 51. Which of the following is NOT a typical cause of coating blistering on offshore structures? A) Trapped moisture beneath the coating B) High substrate temperature during cure
