LGTCO/LGTF exit exam questions and answers — Set 5 — Liquefied Gas Tanker Cargo Operations
Set 5 of the Liquefied Gas Tanker Cargo Operations (LGTCO/LGTF) exit exam bank — 30 of 599 questions, with the correct option marked and a one-line explanation for every one. Read it end to end, jump to a single set, or search it — then sit the same bank as a timed paper. The real DG Shipping exit exam is 30 marks with 15 to pass.
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Set 5 — 30 LGTCO/LGTF exit exam questions with answers
1. Semi-pressurized ships capable of withstanding carriage temperatures of down to -48°C are designed to carry which cargo?
- A. LNG
- B. Ethylene
- C. Ethane
- D. LPG (Propane and Butane)
2. Semi-pressurized ships capable of withstanding carriage temperatures down to -104°C cannot carry which of the following cargoes?
- A. Methane (LNG)
- B. Propane
- C. Butane
- D. Ethylene
3. In the case of a typical fully pressurized ship carrying cargo at ambient temperatures, what is the maximum design working pressure of the cargo tanks?
- A. 0.7 barg
- B. 18 barg
- C. 5 to 7 barg
- D. 9 barg
4. The deepwell or submersible cargo pumps used for pumping liquefied gases are of which design type?
- A. Rotary vane type
- B. Gear type
- C. Reciprocating piston type
- D. Centrifugal type
5. For a typical semi-pressurized ship, cargo tanks and associated equipment are designed for what working pressure?
- A. Approximately 5 to 7 barg and a vacuum of 0.5 barg
- B. Approximately 18 barg
- C. Approximately 9 barg and a vacuum of 1.0 barg
- D. Approximately 0.7 barg and a vacuum of 1.0 barg
6. State the typical thickness of the primary metal membrane in membrane LNG tanks:
- A. 2.0 to 3.7 mm thick
- B. 0.7 to 1.5 mm thick
- C. 4.0 to 5.0 mm thick
- D. 8.5 to 10.0 mm thick
7. State the carriage temperature for Propane at atmospheric pressure:
- A. -161.5°C
- B. -88.6°C
- C. -42.3°C
- D. -0.5°C
8. State the carriage temperature for Ethylene Oxide at atmospheric pressure:
- A. 15.8°C
- B. -7.2°C
- C. -23.8°C
- D. 10.7°C
9. State the carriage temperature for Propylene Oxide at atmospheric pressure:
- A. 9.6°C
- B. 34.2°C
- C. -7.2°C
- D. -10.2°C
10. Dräger detector tubes and hand bellows pump are primarily used to measure which type of gas?
- A. Toxic gas
- B. Flammable gas % LEL
- C. Oxygen percentage
- D. Inert gas volume
11. Which of the following liquefied gases is non-flammable?
- A. Chlorine
- B. Ethylene
- C. Ethylene oxide
- D. Propylene oxide
12. Which of the following liquefied gases is categorized as toxic under the IGC Code?
- A. Ethylene
- B. Propylene
- C. Chlorine
- D. Methane
13. The fixed gas-detection system's alarm on a gas carrier is activated when flammable vapour concentration reaches:
- A. 10% of the Lower Explosive Limit (LEL)
- B. 30% of the Lower Explosive Limit (LEL)
- C. 20% of the Lower Explosive Limit (LEL)
- D. 40% of the Lower Explosive Limit (LEL)
14. Which statement correctly applies to Independent Type C cargo tanks?
- A. A full secondary barrier is required
- B. No secondary barrier is required
- C. A partial secondary barrier in the form of a drip tray is always mandatory
- D. Must be fitted with membrane insulation barriers
15. For safe cargo tank entry, toxic gas concentration must be verified below:
- A. Less than the OEL (Occupational Exposure Limit)
- B. Less than 80% of the OEL
- C. Less than 50% of the OEL / TLV
- D. Less than 60% of the OEL
16. What is the primary extinguishing chemical filled in an ABC-rated Dry Chemical Powder (DCP) extinguisher?
- A. Potassium bicarbonate
- B. Sodium bicarbonate
- C. Mono-ammonium phosphate
- D. Sodium, magnesium and aluminium powder
17. What is the chemical powder filled in a standard BC-rated DCP fire extinguisher?
- A. Potassium bicarbonate urea
- B. Sodium bicarbonate
- C. Mono-ammonium phosphate
- D. Calcium hydroxide
18. Under maritime international standards, what class of fire does a flammable gas fire fall under?
- A. Class A fire
- B. Class B fire
- C. Class C fire
- D. Class D fire
19. Under maritime international standards, what class of fire does a flammable liquid fire fall under?
- A. Class A fire
- B. Class B fire
- C. Class C fire
- D. Class D fire
20. What is the propellant gas used in fixed dry chemical powder (DCP) fire-fighting systems on gas carrier decks?
- A. Oxygen
- B. Compressed atmospheric air
- C. Acetylene
- D. Nitrogen
21. Running two identical centrifugal cargo pumps in parallel will result in:
- A. Almost double the discharge pressure with the same discharge rate
- B. Almost double the discharge flow rate with discharge pressure largely unchanged
- C. Double discharge rate and double discharge pressure simultaneously
- D. The exact same discharge pressure and rate as running one pump
22. Whether cargo tanks are of Type 'A', 'B' or 'C', a complete double hull is required for carriage of liquefied gas cargoes below what temperature?
- A. -88°C
- B. -55°C
- C. -104°C
- D. -162°C
23. What is the minimum water application rate of the fixed water spray system for fire protection purposes on horizontal deck surfaces?
- A. 10 litres/m² per minute
- B. 4 litres/m² per minute
- C. 20 litres/m² per minute
- D. 15 litres/m² per minute
24. What is the minimum water application rate of the fixed water spray system for fire protection purposes on vertical surfaces?
- A. 8 litres/m² per minute
- B. 4 litres/m² per minute
- C. 12 litres/m² per minute
- D. 15 litres/m² per minute
25. In fixed gas-detection systems on board gas carriers, the Gas Codes mandate that sampling intervals from any one space must not exceed:
- A. 60 minutes
- B. 30 minutes
- C. 45 minutes
- D. 20 minutes
26. What is the name of the statutory certificate issued by a Flag Administration confirming that a gas carrier complies with the IGC/GC Gas Code?
- A. Certificate of Construction
- B. Load Line Certificate
- C. Safety Construction Certificate
- D. International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk
27. Which space is defined as the space enclosed by the ship's structure in which a cargo containment system is situated?
- A. Interbarrier space
- B. Hold space
- C. Void space
- D. Cofferdam
28. Which petroleum gases does commercial LPG mainly consist of?
- A. Ethane & Pentane
- B. Butadiene & Ammonia
- C. Chlorine & Ethylene
- D. Propane & Butane
29. What is the primary purpose of inerting on a liquefied gas carrier?
- A. To prevent flammable vapour/air mixtures in cargo tanks and associated piping
- B. To increase oxygen content in vapour/air mixtures in tanks
- C. To increase hydrocarbon concentration in vapour/air mixtures
- D. To pressurize cargo tanks for deepwell pump suction
30. What is the limitation of a catalytic combustion type combustible gas detector (explosimeter)?
- A. It cannot be used for measurement in air
- B. It cannot be used for measurement in an inert (oxygen-deficient) atmosphere such as nitrogen
- C. It cannot be used for measuring methane
- D. It cannot be used in an atmosphere containing 21% oxygen
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