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GASCO exit exam questions and answers — Set 5

Set 5 of the Advanced Training for Liquefied Gas Tanker Cargo Operations (GASCO) exit exam bank — 30 of 351 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.

These are the bank's original groupings. Practising deals the whole bank out again every time you reshuffle, so a practice “Set 3” is a different 30 questions each time — the set numbers below are the source file's, and are only used here so the key stays navigable. Options are listed in their original order with fixed letters; when you practise, those move too.

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Set 5 — 30 GASCO exit exam questions with answers

1. What are the symptoms of Asphyxiant , when LPG and LNG carried as cargo?

  • A. Increased rate and dept of respiration and loss of consciousness
  • B. Blueness of the skin (Cyanosis)
  • C. Stertorous breathing with a snoring sound
  • D. All of the abov
Answer: D — All of the abov
The correct answer is All of the abov. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

2. Inert gas- How is sea water supplied to the deck seal ?

  • A. Through the main sea water pumps or through the condenser cargo pump
  • B. Through a sea water aggregate pump fitted on the cargo deck
  • C. Through the deck fire lin
  • D. Through the deck seal pump fitted in the engine room
Answer: D — Through the deck seal pump fitted in the engine room
The correct answer is Through the deck seal pump fitted in the engine room. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

3. On tank vessels, which of these valve types is most commonly used in conjunction with hydraulically actuated controls?

  • A. Non return valves
  • B. Globe valves
  • C. Butterfly valves
  • D. Gate valves
Answer: C — Butterfly valves
The correct answer is Butterfly valves. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

4. What is critical temperature of methane in °Celsius ?

  • A. -82.5
  • B. 82.5
  • C. 52.8
  • D. None of the abov
Answer: A — -82.5
The correct answer is -82.5. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

5. On tank vessels equipped with the power operated cargo tank valves, the type of power operator most commonly used is _____

  • A. Hydraulic
  • B. Electric
  • C. Steam
  • D. Diesel
Answer: A — Hydraulic
The correct answer is Hydraulic. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

6. The valve best suited for throttling gas or liquid flow in a pipe line is the _____

  • A. Globe valv
  • B. Gate valv
  • C. Check valv
  • D. Pug cock
Answer: A — Globe valv
The correct answer is Globe valv. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

7. What is the boiling point at atmospheric pressure of ammonia

  • A. -42 °Celsius
  • B. -34 °Celsius
  • C. -5 °Celsius
  • D. None of the abov
Answer: B — -34 °Celsius
Anhydrous ammonia (NH3) has an atmospheric boiling point of -33.4°C (approximately -34°C).

8. Which tanks are completely supported self-supporting and do not form part of the ship's hull structure

  • A. Independent tanks
  • B. Membrane tank
  • C. Semi membranee tank
  • D. None of the abov
Answer: A — Independent tanks
The correct answer is Independent tanks. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

9. Ammonia forms explosive compounds with

  • A. Mercury alon
  • B. Mercury, chlorine, iodine, bromine, calcium, silver oxide and silver hypo chlorit
  • C. Silica
  • D. Water
Answer: B — Mercury, chlorine, iodine, bromine, calcium, silver oxide and silver hypo chlorit
The correct answer is Mercury, chlorine, iodine, bromine, calcium, silver oxide and silver hypo chlorit. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

10. A bigger spell of LPG will be visible as a _____ which is condensed water vapour from the atmosphere

  • A. White cloud
  • B. Blue cloud
  • C. Black cloud
  • D. None of the abov
Answer: A — White cloud
The correct answer is White cloud. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

11. How is BOIL OFF gas generated

  • A. Evaporation
  • B. Heat ingress
  • C. Drop in pressure
  • D. All of the abov
Answer: D — All of the abov
Boil-Off Gas (BOG) is the continuous natural vaporization of cryogenic liquefied gas (like LNG at -161.5°C) caused by ambient heat ingress through the cargo tank insulation.

12. In addition to water detection sensors fitted at secondary insulation spaces, which is the other typical sensing devices fitted to give an early indication of inner hull experiencing structural failure?

  • A. Water moisture detector inside primary insulation spac
  • B. Water moisture detector at the vapor dom
  • C. Water moisture detector inside secondary insulation spac
  • D. Water moisture detector inside wing ballast tank
Answer: C — Water moisture detector inside secondary insulation spac
The correct answer is Water moisture detector inside secondary insulation spac. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

13. Which of the following can lead to major leak of insulation spaces?

  • A. Due to hair line cracks inside membranee.
  • B. Due to significant fatigue cracks on welds of cargo tank membranees
  • C. The gradual increase of methane content inside the insulation spac
  • D. Due to accidentally tripped of both HD and LD compressors
Answer: B — Due to significant fatigue cracks on welds of cargo tank membranees
The correct answer is Due to significant fatigue cracks on welds of cargo tank membranees. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

14. Which of the following equipment is not used to lift an auxiliary cargo pump?

  • A. Electrical connection box
  • B. Chain block
  • C. Overhead railing
  • D. Manifold spool piece derrick
Answer: D — Manifold spool piece derrick
The correct answer is Manifold spool piece derrick. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

15. What will happen to the liquid level within and pressure of a cargo tank when there is a big crack (major leak) in the cargo tank's primary membrane and adjacent insulation space, underneath the cargo level?

  • A. The liquid level will increase and pressuree will suddenly increas
  • B. The liquid level will drop and pressuree will suddenly drop
  • C. The liquid level will drop and pressuree will suddenly ris
  • D. The liquid level will increase and pressuree will be suddenly drop
Answer: C — The liquid level will drop and pressuree will suddenly ris
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

16. Onboard an LNG carrier, with NO 96 containment system, what is the maximum allowable differential head between the cargo tank and primary spaces liquid level during discharge operation from the damaged tank?

  • A. 100 mm of cargo level
  • B. 500 mm of cargo level
  • C. 50 mm of cargo level
  • D. 10 mm of cargo level
Answer: B — 500 mm of cargo level
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

17. In the event of major LNG spill which of the following action should not to be taken?

  • A. Stop cargo operation
  • B. Inject cargo line with CO2, without stopping the cargo operation
  • C. Close all accommodation doors and ventilation fans
  • D. Start the deck water spray (or IMO) pump
Answer: B — Inject cargo line with CO2, without stopping the cargo operation
The correct answer is Inject cargo line with CO2, without stopping the cargo operation. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

18. What is the method used to prevent any further lowering of the hull steel temperature due to damaged insulation?

  • A. By flooding the ballast tanks with CO2 around the affected cargo tank
  • B. By sending ship's crew to scaling off the ice formed on the surfaces of the hull steel
  • C. By injecting nitrogen gas inside the ballast tanks around the affected cargo tank
  • D. By flooding ballast tanks with sea water around any affected cargo tank
Answer: D — By flooding ballast tanks with sea water around any affected cargo tank
The correct answer is By flooding ballast tanks with sea water around any affected cargo tank. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

19. Which is the melting point temperature of the ESDS automatic fusible element normally fitted onboard?

  • A. Between 200°C to 206°C
  • B. Between 50°C to 55°C
  • C. Between 72°C to 78°C
  • D. Between 98°C to 104°C
Answer: D — Between 98°C to 104°C
ESDS automatic fusible thermal elements are designed to melt between 98°C and 104°C during a fire, depressurizing the pneumatic loop and tripping the emergency shutdown system.

20. Identify the odd one. Onboard an LNG tanker with NO 96 containment system, which of the following is not a typical early indication of a major cargo leak into the insulation spaces?

  • A. There will be a rapid increase of methane content in affected areas
  • B. Relief valve for the affected primary space may lift
  • C. Inner hull temperature will drop in affected areas
  • D. There will be cold spots at the ship side close to the affected area
Answer: D — There will be cold spots at the ship side close to the affected area
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

21. Which of the following portable gas meters is used to monitor methane content during the inerting operation prior aerating?

  • A. M2 test tub
  • B. Hygrometer
  • C. Oxygen meter
  • D. Gas scop
Answer: D — Gas scop
The correct answer is Gas scop. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

22. Onboard a membrane class LNG tanker, during purging cargo tanks with LNG, where is the sampling point for taking the gas readings?

  • A. Vaporiser outlet sample cock
  • B. Heater outlet sample cock
  • C. Vapor line sample cock
  • D. At cargo tank loading line sample cock
Answer: D — At cargo tank loading line sample cock
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

23. Onboard an LNG tanker, why is forced boil - off required out during loaded passage?

  • A. To maintain cargo tank pressurees
  • B. To maintain cargo tank temperatures
  • C. To maintain cold temperature at the tripod mast
  • D. To supplement fuel supply to the main propulsion plant
Answer: D — To supplement fuel supply to the main propulsion plant
The correct answer is To supplement fuel supply to the main propulsion plant. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

24. If there is an interruption at the end of cooldown before loading, what is the recommended measure to be taken?

  • A. To stop cooldown completely and open loading valv
  • B. To stop cooldown and close the vapor manifold
  • C. To start own spray pump and cool down
  • D. To continue cooldown process until the tank bottom close to -160°C.
Answer: D — To continue cooldown process until the tank bottom close to -160°C.
The correct answer is To continue cooldown process until the tank bottom close to -160°C.. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

25. Can ballast operations take place during custody transfer measurement?

  • A. Yes, ballasting should be done to maintain even keel
  • B. Ship should be maintained upright by ballasting
  • C. No; all ballast operations should be suspended
  • D. There are no restrictions on ballast operations
Answer: C — No; all ballast operations should be suspended
The correct answer is No; all ballast operations should be suspended. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

26. What is the medium used for inerting cargo tanks?

  • A. Oxygen
  • B. Inert gas
  • C. Dry air
  • D. Methan
Answer: B — Inert gas
The correct answer is Inert gas. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

27. What is the main reason for a membrane class LNG tanker to retain a small quantity of cargo ("heel") during ballast passage?

  • A. To ensure easy starting of cargo pump at loading port
  • B. To reduce the consumption of heavy fuel oil on passage
  • C. To avoid bottom of the cargo tank come into contact with oxygen
  • D. For cold maintenance of the cargo tanks
Answer: D — For cold maintenance of the cargo tanks
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

28. Which equipment Is used for evacuating the Insulation spaces?

  • A. Vacuum pumps
  • B. HD blowers
  • C. LD blowers
  • D. Water ballast ejector
Answer: A — Vacuum pumps
The correct answer is Vacuum pumps. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

29. Safety is dependent on orderliness and cleanliness. Order may be maintained by______.

  • A. storing items in their assigned plac
  • B. storing all items in a common storage container except those ready-for-sea
  • C. tagging all items according to their age and then storing them together
  • D. disposing of used items
Answer: A — storing items in their assigned plac
The correct answer is storing items in their assigned plac. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

30. Oxygen in the atmosphere of the tank is used up when iron is converted into oxides during the corrosion process. ---------------i in the tanks prior to entry.

  • A. Copious quantity of fresh air
  • B. Space to have a minimum oxygen level for sustaining lif
  • C. Pressurized oxygen pumped
  • D. Space to be ventilated for 24 hours
Answer: B — Space to have a minimum oxygen level for sustaining lif
The correct answer is Space to have a minimum oxygen level for sustaining lif. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

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