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GASCO exit exam questions and answers — Set 11

Set 11 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 11 — 30 GASCO exit exam questions with answers

1. Where are the spray and stripping pumps normally installed onboard an LNG tanker?

  • A. At the end of cargo pipes in cargo pump room
  • B. At main deck close to liquid dome fittings
  • C. Inside cargo tanks at the bottom end of tripod mast
  • D. At main deck close to vapor dome fittings
Answer: C — Inside cargo tanks at the bottom end of tripod mast
The correct answer is Inside cargo tanks at the bottom end of tripod mast. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

2. In an Air Dryer Plant in the first stage of drying process the air is cooled to around 5 degree by R 404A refrigeration plant during the second stage what drying agents is used to remove the remaining moisture?

  • A. Silica gel
  • B. Activated alumina
  • C. Perlite
  • D. Invar powder
Answer: B — Activated alumina
The correct answer is Activated alumina. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

3. When using the main vaporizer to vaporize liquid nitrogen what should be fitted at the inlet of the vaporizer?

  • A. A removable bend
  • B. A gas filter
  • C. A valv
  • D. A liquid nitrogen detector
Answer: A — A removable bend
The correct answer is A removable bend. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

4. During the nitrogen or cooling cycle in a reliquefaction plant, nitrogen is compressed in 3-stage centrifugal compressor. How is the compressor cooled?

  • A. Water cooling
  • B. Propane cooling / Butane cooling
  • C. Butane cooling
  • D. LNG cooling
Answer: A — Water cooling
The correct answer is Water cooling. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

5. How should the activated alumina in the drying tank be regenerated after the dry air unit has been in use for sometimes (for about 20 hours) or when the high humidity alarm is given?

  • A. Shutting down the unit and restart the whole plant
  • B. Warming up the activated alumina outside the tank
  • C. Back-flushing hot air through the tank
  • D. Free flow air through the tank
Answer: C — Back-flushing hot air through the tank
The correct answer is Back-flushing hot air through the tank. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

6. In the LNG re-liquefaction plant, Identify the factor with which the boil-off gas compressor capacity is adjusted automatically?

  • A. LNG vapour density
  • B. LNG heat valu
  • C. LNG Boll-off Rate(BOR)
  • D. LNG liquid density
Answer: C — LNG Boll-off Rate(BOR)
The correct answer is LNG Boll-off Rate(BOR). This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

7. How is the LNG boil-off gas removed from the cargo tanks brought to the reliquefaction plant?

  • A. By boll-off gas expanders
  • B. By low-duty compressors
  • C. By forcing vaporizer
  • D. By force draught fans
Answer: B — By low-duty compressors
The correct answer is By low-duty compressors. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

8. What is fitted to at the outlet of main and forcing steam vaporizers to ensure a stable output and avoid accumulation of non-vaporized liquid?

  • A. Demister
  • B. Spiral wires
  • C. A re-evaporator
  • D. Condensate level controller
Answer: C — A re-evaporator
The correct answer is A re-evaporator. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

9. Normally for an air dryer plant, where possible; "regeneration process must be completed at least two (2) weeks before using the dry air plant. What does this action ensure?

  • A. Residual heat in the regenerated drier is kept within the plant
  • B. Residual heat in the generated crier to dissipated
  • C. Residual heat in the regenerated drier is increased
  • D. Residual heat in the regenerated drier is not disturbed
Answer: B — Residual heat in the generated crier to dissipated
The correct answer is Residual heat in the generated crier to dissipated. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

10. Why is necessary to purge the auxiliary cargo pump column before the installation can commence?

  • A. To reduce the tank pressure
  • B. to ensure the column is filled to the top with cargo
  • C. To purge out the liquid (cargo) through bottom valve at ensure the column is inerted
  • D. To purge the air out through bottom valve and ensure column is inerted
Answer: C — To purge out the liquid (cargo) through bottom valve at ensure the column is inerted
The correct answer is To purge out the liquid (cargo) through bottom valve at ensure the column is inerted. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

11. LNG tankship submerged cargo pump running procedure will not include,

  • A. The cargo pumps may be restarted after a failed start, a maximum of 4 times excluding the failed attempt
  • B. This procedure must be adhered to as heat build-up from the high starting current may not be carried away during stripping operations
  • C. This may be due to the lack of liquid flow when (and if) the pump does not prime, due to the extremely low level of LNG during stripping operations
  • D. Up to 30 seconds of operation with dry suction but with fluid in the discharge pipe will not damagee the pump or the motor
Answer: A — The cargo pumps may be restarted after a failed start, a maximum of 4 times excluding the failed attempt
The correct answer is The cargo pumps may be restarted after a failed start, a maximum of 4 times excluding the failed attempt. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

12. What is an LNG carrier provided with to heat up LNG Vapeur delivered from compressors or vaporizers?

  • A. Steam heated forcing vaporizers
  • B. Steam generators
  • C. Steam heated gas heaters
  • D. Glycol water heated gas
Answer: C — Steam heated gas heaters
The correct answer is Steam heated gas heaters. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

13. Of the two critical equipment of a typical membrane method nitrogen generator, one is the heater. Identify the other from option given

  • A. Methane analyzer
  • B. Carbon dioxide analyzer
  • C. Oxygen analyzer
  • D. Nitrogen analyzer
Answer: C — Oxygen analyzer
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

14. Which cargo tank level measuring system is commonly used as a primary system?

  • A. Radar tank gaug
  • B. Nitrogen bubbler gaug
  • C. float gauges
  • D. steel tape measurements
Answer: A — Radar tank gaug
The correct answer is Radar tank gaug. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

15. Liquefied gas carriers are normally loaded or unloaded through__________situated amidships.

  • A. Cargo pumps
  • B. Manifolds
  • C. stripping pumps
  • D. ESD valves
Answer: B — Manifolds
The correct answer is Manifolds. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

16. What test is carried out to ensure that all stripping / spray pumps are operational? Hint: this test is is often done after leaving the loading port as it is allows time for installation of an auxiliary cargo pump should it be necessary.

  • A. Snip test
  • B. Meggar test
  • C. cold test
  • D. load test
Answer: B — Meggar test
The correct answer is Meggar test. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

17. What is the approximate temperature desired on board on LNG tanker, for the output from the forcing vaporizer?

  • A. -70C
  • B. -40C
  • C. -60C
  • D. -50C
Answer: B — -40C
The correct answer is -40C. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

18. What is the purpose of having a cofferdam heating system?

  • A. To generate sufficient boil- off to sustain dual fuel firing for the boiler in engine room.
  • B. To ensure that the cofferdam and liquid domes spaces are at all time kept at +5C when at loaded voyag
  • C. To increase cargo temperature before arrival at discharge terminal
  • D. To ensure efficiency of vaporizer operation during the cooling down operation
Answer: B — To ensure that the cofferdam and liquid domes spaces are at all time kept at +5C when at loaded voyag
The correct answer is To ensure that the cofferdam and liquid domes spaces are at all time kept at +5C when at loaded voyag. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

19. Which of the following options is an exception in a typical LNG boil off gas reliquefication plant?

  • A. cargo cycl
  • B. forced vaporization
  • C. nitrogen or cooling vaporization
  • D. auxiliary cycl
Answer: B — forced vaporization
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.

20. After extinguishing a paint locker fire using the fixed CO2 system, the next immediate action is for the space to be

  • A. opened and burned material removed
  • B. left closed with ventilation off until all boundaries are cool
  • C. checked for the proper oxygen level
  • D. opened and doused with water to prevent reflash
Answer: B — left closed with ventilation off until all boundaries are cool
The correct answer is left closed with ventilation off until all boundaries are cool. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

21. which of the following conditions can contribute to accidents ?

  • A. good housekeeping
  • B. inspections
  • C. unsafe conditions
  • D. intelligent work habits
Answer: C — unsafe conditions
The correct answer is unsafe conditions. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

22. which chemical is used to treat water in order to ensure its safety for drinking?

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

23. what is the typical measuring range for an oxygen analyzer?

  • A. 10ppm volume oxygen in air
  • B. 0- 25% volume oxygen in air
  • C. 0-5% volume oxygen in air
  • D. 0-100% volume oxygen in air
Answer: B — 0- 25% volume oxygen in air
The correct answer is 0- 25% volume oxygen in air. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

24. What is typically the first action taken when there is a serious primary membrane leak?

  • A. Equalize the primary insulation space and vapor dome pressurees of the affected cargo tank
  • B. Stop filling the affected cargo tank's primary insulations with nitrogen
  • C. open up the affected cargo tank's primary insulations with inspection
  • D. Warming up the affected cargo tank immediately
Answer: A — Equalize the primary insulation space and vapor dome pressurees of the affected cargo tank
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

25. On an LNG tanker, during discharging why is it necessary to maintain the trim of 3m by stern during final discharging before completion of bulk discharge?

  • A. To ensure proper draining of ballast water from ballast tank
  • B. to increase boil-off of cargo while discharging
  • C. to ensure maximum discharge of cargo prior to warming up of cargo tanks
  • D. to maximize boil-off of cargo with by increased exposed surface area
Answer: C — to ensure maximum discharge of cargo prior to warming up of cargo tanks
The correct answer is to ensure maximum discharge of cargo prior to warming up of cargo tanks. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

26. Onboard an LNG carrier, during loading operations, why should be- ballasting be done concurrently with loading?

  • A. to reduce vessel turnaround tim
  • B. to keep the vessel within the required limit of draft, trim, stress and stabilty
  • C. to ensure that the gangway is safe for use at all times
  • D. deballasting can be done after 50% loading is complet
Answer: B — to keep the vessel within the required limit of draft, trim, stress and stabilty
The correct answer is to keep the vessel within the required limit of draft, trim, stress and stabilty. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

27. What is the average recommended cooling down rate of cargo tanks?

  • A. 20-22 °C/ hour
  • B. 10-12 °C/ hour
  • C. 30-32 °C/ hour
  • D. 40-42 °C/ hour
Answer: B — 10-12 °C/ hour
The correct answer is 10-12 °C/ hour. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

28. What is the objective of drying cargo tanks?

  • A. to warm the cargo tanks prior to inerting
  • B. to remove methane residual
  • C. to prevent damagee of cargo equipment
  • D. to reduce moisture content
Answer: D — to reduce moisture content
The correct answer is to reduce moisture content. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

29. Onboard an LNG carrier, during loading operation which is the correct sequence of liquid flow during loading operation?

  • A. terminal- spary line- main liquid line- tank filling val
  • B. terminal- manifold crossover- main liquid line- tank filling val
  • C. terminal- manifold crossover - main vapor line- tank filling val
  • D. terminal-manifold crossover - main liquid line- spary lin
Answer: B — terminal- manifold crossover- main liquid line- tank filling val
The correct answer is terminal- manifold crossover- main liquid line- tank filling val. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

30. Where is the cargo tanks warming up operation normally carried out?

  • A. in port when alongside as this is a routine, non-critical operation
  • B. it can be done anywhere but at sea as shore support is required
  • C. in sheltered waters where the mixture can be exhausted without danger
  • D. it is done after entry into the drydock
Answer: C — in sheltered waters where the mixture can be exhausted without danger
The correct answer is in sheltered waters where the mixture can be exhausted without danger. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

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