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GASCO exit exam questions and answers — Set 7

Set 7 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 7 — 30 GASCO exit exam questions with answers

1. In an LNG carrier mixtures of methane and air are avoided at all times. What is the reason?

  • A. Dilution of cargo
  • B. Risk of fire or explosion
  • C. Degradation of cargo quality
  • D. Ice formation in cargo
Answer: B — Risk of fire or explosion
Methane-air mixtures within the flammable range (5% to 15% methane by volume) pose severe risks of fire and explosion, so tanks are inerted with inert gas or nitrogen before introducing air or cargo.

2. Which flammability diagram is used to observe change in cargo tank atmosphere for an LNG gas carrier?

  • A. Methane and nitrogen mixtures
  • B. Methane and oxygen mixtures
  • C. Methane and air mixtures
  • D. Methane, oxygen and nitrogen mixtures
Answer: D — Methane, oxygen and nitrogen mixtures
The correct answer is Methane, oxygen and nitrogen mixtures. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

3. What is the maximum interval of time between sampling and analyzing for each sampling head location sequentially?

  • A. Not exceeding 50 minutes interval
  • B. Not exceeding 30 minutes interval
  • C. Not exceeding 40 minutes interval
  • D. Not exceeding 60 minutes interval
Answer: B — Not exceeding 30 minutes interval
The correct answer is Not exceeding 30 minutes interval. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

4. How can a gas be liquefied?

  • A. By mixing gases of higher specific density
  • B. By the application of pressuree or by cooling
  • C. By fusion in a closed chamber
  • D. By evaporation in a closed chamber
Answer: B — By the application of pressuree or by cooling
The correct answer is By the application of pressuree or by cooling. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

5. What is the IGC code definition for a liquefied gas?

  • A. Product having a saturated vapor pressuree of 2.8 bar absolute at 37.8°C/100°F
  • B. Product having a saturated vapor pressuree of 1.76 bar absolute at 37.8°C/ 100 ° F
  • C. Product having a saturated vapor pressuree of 1.76 bar absolute at 38.7°C/1029 F
  • D. Product having a saturated vapor pressuree of 2.8 bar absolute at 38.7°C/102° F
Answer: A — Product having a saturated vapor pressuree of 2.8 bar absolute at 37.8°C/100°F
The correct answer is Product having a saturated vapor pressuree of 2.8 bar absolute at 37.8°C/100°F. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

6. During heat transfer from one body to another, what transfer takes place?

  • A. Molecul
  • B. Energy
  • C. Power
  • D. Electron
Answer: B — Energy
The correct answer is Energy. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

7. Why is adequate heel retained during short ballast voyages?

  • A. It is done as cargo tanks cannot be stripped completely
  • B. It reduces the ballast to be taken and thus improves turn around
  • C. It reduces boil-off rates during the ballast voyag
  • D. It enables loading without further cool down on arrival
Answer: D — It enables loading without further cool down on arrival
Retaining a small heel of LNG cargo on ballast voyages maintains tank cryogenic temperatures, minimizes thermal shock, and avoids lengthy pre-cooling at the loading port.

8. Identify the industry body which is associated with LNG industry although its major stakeholders are from the oil industry?

  • A. The Oil Companies International Marine Forum (OCIMF)
  • B. The Oil Charterers International Marine Forum (OCIMF)
  • C. The Oil & Gas Terminals International Marine Forum (OTIMF)
  • D. The Oil Terminals International Marine Forum (OTIMF)
Answer: A — The Oil Companies International Marine Forum (OCIMF)
The correct answer is The Oil Companies International Marine Forum (OCIMF). This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

9. Who are the stakeholders represented by the Society of International Gas Tanker & Terminal Operators Ltd (SIGTTO)?

  • A. Liquefied gas importing countries
  • B. Liquefied gas shipping and terminals
  • C. Liquefied gas exporting countries
  • D. Liquefied gas pipeline owners
Answer: B — Liquefied gas shipping and terminals
SIGTTO (Society of International Gas Tanker and Terminal Operators) represents liquefied gas tanker operators, terminal owners, and industry stakeholders worldwide.

10. Which is the typical temperature trend that indicates a membrane failure?

  • A. No change in insulation spaces temperature of affected cargo tanks
  • B. Increase in affected cargo tanks' temperatur
  • C. Decrease in affected cargo tank's temperatur
  • D. A decrease in secondary spaces temperature of affected cargo tanks
Answer: D — A decrease in secondary spaces temperature of affected cargo tanks
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

11. What is the use of thermocouples fitted at the surface of the inner hull?

  • A. To monitor cargo tank temperatur
  • B. To monitor the inner steel temperatur
  • C. To monitor hull stresses
  • D. To monitor inner hull paint thickness
Answer: B — To monitor the inner steel temperatur
The correct answer is To monitor the inner steel temperatur. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

12. What shall be followed upon after a major LNG spill?

  • A. Nothing to be done to any affected areas
  • B. All the affected areas shall be sealed off untll next dry dock repairs
  • C. All the affected areas shall be wash with oil remover
  • D. All affected areas shall be thoroughly inspected for any signs of cold shock fractures
Answer: D — All affected areas shall be thoroughly inspected for any signs of cold shock fractures
The correct answer is All affected areas shall be thoroughly inspected for any signs of cold shock fractures. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

13. What can lead to LNG (cargo) leak into primary insulation spaces?

  • A. Fatigue crack on ship hull
  • B. Fatigue cracks on primary membrane
  • C. Fatigue cracks on secondary membrane
  • D. Fatigue crack on ballast tank stiffener
Answer: B — Fatigue cracks on primary membrane
The correct answer is Fatigue cracks on primary membrane. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

14. The LNG cargo tank insulation system is designed to perform the following, EXCEPT:-

  • A. Maintain the boil - off losses from the cargo at an acceptable level
  • B. Protect cargo valves and piping
  • C. Protect the inner hull steel from the effect of excessively low temperatur
  • D. Reduce heat transfer from the outside into cargo tank
Answer: B — Protect cargo valves and piping
The correct answer is Protect cargo valves and piping. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

15. Where is the secondary insulation pump well typically located?

  • A. Aft of each tank secondary insulation spac
  • B. Forward of each tank secondary insulation spac
  • C. Centre of each tank secondary insulation spac
  • D. Top of each tank secondary insulation spac
Answer: A — Aft of each tank secondary insulation spac
The correct answer is Aft of each tank secondary insulation spac. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

16. Which of the following may not contribute to structural failure of inner hull?

  • A. Destruction of inner hull due to ship grounding
  • B. Destruction of ship side due to collision
  • C. Destruction of Ballast pump during high speed operation
  • D. Destruction of the insulation space due to sloshing effect
Answer: C — Destruction of Ballast pump during high speed operation
The correct answer is Destruction of Ballast pump during high speed operation. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

17. During a cargo handling operation which of the following precautions need not be observed to deal with spillage?

  • A. Fire fighting equipment on standby mod
  • B. Manifold shipside water spray curtain used
  • C. Ship cordoned off with LNG containment boom
  • D. Deck fire main on standby mod
Answer: C — Ship cordoned off with LNG containment boom
The correct answer is Ship cordoned off with LNG containment boom. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

18. On an LNG tanker, why ballasting operation is carried out concurrently with LNG discharging operation?

  • A. To ensure stability criteria is met at all times
  • B. To ensure vessel has sufficient trim for discharging
  • C. To ensure easy shore gangway adjustment
  • D. To maintain manifold alignment with shore marker
Answer: A — To ensure stability criteria is met at all times
The correct answer is To ensure stability criteria is met at all times. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

19. What will happen if cold LNG Boil - Off Gas (BOG) vented through the mast riser?

  • A. Mast riser will frozen up and it is possible to crack
  • B. Methane vapor will caught fire immediately
  • C. Methane vapor will be tuming back to LNG liquid
  • D. Big white plume will be produced
Answer: D — Big white plume will be produced
The correct answer is Big white plume will be produced. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

20. Traces of inert gas constituents may be present even after aerating. What are the limits for carbon dioxide (CO2) and carbon monoxide?

  • A. CO2 <1.5% BV and CO <150ppm
  • B. CO2 <1.5% BV and CO <250ppm
  • C. CO2 <1.0%BV and CO <50ppm
  • D. CO2 <0.5% BV and CO <50ppm
Answer: D — CO2 <0.5% BV and CO <50ppm
The correct answer is CO2 <0.5% BV and CO <50ppm. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

21. What should be done before commencing unloading test?

  • A. Ship should provide specifications to port
  • B. Exchange of ship - shore safety plan
  • C. Terminal should provide specifications to port
  • D. Ship and terminal should test the ship's pumps
Answer: B — Exchange of ship - shore safety plan
The correct answer is Exchange of ship - shore safety plan. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

22. During a long ballast passage which method of retaining heel onboard produces less boil-off?

  • A. Heel is retained in a center tank and sprayed in others
  • B. Heel is retained in alternate tanks
  • C. Heel is retained in 50% of the tanks
  • D. Adequate heel is retained in all the tanks
Answer: D — Adequate heel is retained in all the tanks
Retaining a small heel of LNG cargo on ballast voyages maintains tank cryogenic temperatures, minimizes thermal shock, and avoids lengthy pre-cooling at the loading port.

23. How do you maintain the cargo tank pressure as low as possible (about 20 - 30 mbar gauge) during inerting operation after gas burning is stopped?

  • A. by continuous venting via vapor dome's safety valves (manually opened)
  • B. by continuous venting via vacuum pump mast riser
  • C. by continuous venting via ship's funnel exhaust
  • D. by continuous venting via dedicated mast riser
Answer: D — by continuous venting via dedicated mast riser
The correct answer is by continuous venting via dedicated mast riser. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

24. What should be the vessel's trim and list during gauging for custody transfer?

  • A. Upright and 1 m down by stern
  • B. Upright and 0.5 m down by stern
  • C. There are no restrictions trim and list
  • D. Upright and even keel
Answer: D — Upright and even keel
The correct answer is Upright and even keel. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

25. Fire fighters can control small LNG fire by using____________.

  • A. water
  • B. water mixed with ail
  • C. high expansion foam
  • D. dry chemical powder
Answer: D — dry chemical powder
The correct answer is dry chemical powder. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

26. Smoke detectors are classified into the following:

  • A. Photoelectric typ
  • B. Tonization typ
  • C. Photoelectric type and Ionization typ
  • D. Ionization type smoke detectors are in machinery spaces
Answer: C — Photoelectric type and Ionization typ
The correct answer is Photoelectric type and Ionization typ. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

27. Where do the cargo manifold relief lines, the cargo machinery space relief lines and cargo tanks relief lines lead to?

  • A. They are led to a common riser
  • B. They are led to gas line to engine room
  • C. They are led to vapor domes
  • D. They are led to high duty compressor suction lin
Answer: C — They are led to vapor domes
The correct answer is They are led to vapor domes. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

28. Onboard an LNG tanker, for both main and forcing steam vaporizers it is important to note the output capacity (the amount of LNG liquid turned into LNG vapor). What does this capacity depend on?

  • A. Cooling water supplied to the vaporizers
  • B. Heat supplied to the vaporizers (steam supply)
  • C. Air supplied to the vaporizers
  • D. Condensate returned from the vaporizers
Answer: B — Heat supplied to the vaporizers (steam supply)
The correct answer is Heat supplied to the vaporizers (steam supply). This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

29. Relief valves are used on an LNG carrier liquid header. Identify the correct combination of "set pressure" (lifting pressure) and "reseating pressure" for these valves.

  • A. 100 mbar and 900 mbar
  • B. 10 bar and 9 bar
  • C. 15 bar and 10 bar
  • D. 1000 mbar and 500 mbar
Answer: B — 10 bar and 9 bar
The correct answer is 10 bar and 9 bar. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

30. When does the need to rig the auxiliary cargo pump arise?

  • A. When all the cargo pumps (main and stripping pumps) in a particular tank are out of servic
  • B. When the needs arise to increase flow rate during discharging operation
  • C. In case of one cargo pump of the particular tanks is out of servic
  • D. To increase the loading rate of LNG from shore due to shore pumps is out of servic
Answer: A — When all the cargo pumps (main and stripping pumps) in a particular tank are out of servic
The correct answer is When all the cargo pumps (main and stripping pumps) in a particular tank are out of servic. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

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