Practice Test Geeks(DPO) Dynamic Positioning Operator Exam Practice Test
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Materials Selection Flashcards

7 cards from real DPO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. In DP vessel thruster design, why is nickel-aluminum bronze (NAB) preferred over carbon steel for propeller blades?

    Answer: It offers superior corrosion resistance and antifouling properties in seawater

    NAB resists seawater corrosion and de-alloying, has natural biofouling resistance, and maintains strength at marine operating temperatures, making it ideal for propeller applications.

  2. When a DP class 3 vessel requires redundant hydraulic systems, which seal material is selected for hydraulic cylinders to handle both mineral oil and fire-resistant fluid compatibility?

    Answer: Fluorocarbon (Viton/FKM) seals

    FKM (Viton) seals are compatible with both mineral-based hydraulic oils and fire-resistant fluids (HF-DR, HF-DU types), making them the standard choice for DP hydraulic systems.

  3. Which standard governs the material requirements for structural steel used in the hull of DP offshore vessels built to Class notation?

    Answer: Classification society rules (e.g., DNV, ABS, Lloyd's) referencing IACS UR W11

    IACS UR W11 and individual classification society rules specify notch toughness grades, chemical composition, and testing requirements for hull structural steel.

  4. For DP reference sensor housings mounted below the waterline, which composite material is preferred to avoid interference with acoustic positioning systems?

    Answer: Glass fiber reinforced polymer (GFRP)

    GFRP is acoustically transparent and non-conductive, preventing signal attenuation or reflection that would impair USBL/LBL acoustic positioning sensor performance.

  5. What is the primary reason copper-nickel (Cu-Ni 90/10) alloy is selected for DP vessel seawater piping over austenitic stainless steel?

    Answer: Resistance to microbiologically influenced corrosion (MIC) and biofouling in seawater

    Cu-Ni 90/10 naturally resists biofouling and MIC in seawater systems, reduces the need for chemical dosing, and performs reliably across a wide seawater velocity range.

  6. Which property must be verified when selecting lubricating grease for DP azimuth thruster slewing ring bearings exposed to seawater ingress?

    Answer: Water washout resistance per ASTM D1264

    ASTM D1264 water washout resistance ensures grease remains in bearings despite seawater intrusion, preventing lubricant loss and accelerated bearing wear in DP thrusters.

  7. For DP vessel dynamic cables connecting turret-moored buoys to the vessel, which armor wire material is selected for resistance to hydrogen embrittlement?

    Answer: Stainless steel 316 wire

    Austenitic stainless steel 316 wire is resistant to hydrogen embrittlement unlike high-carbon or martensitic grades, which are susceptible under cathodic protection-induced hydrogen generation.