Skip to content
DG Exit Exam
Home
Answer Key

GASCO exit exam questions and answers — Set 6

Set 6 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.

Bank last rebuilt .

Practise these GASCO questions GASCO mock exit exam, 30 marks GASCO exit exam sets and syllabus

30 of 30 shown · Set 6

Nothing in this set matches that. Try a shorter word, or search the whole key.

Set 6 — 30 GASCO exit exam questions with answers

1. gas pressurizes the liquid out of the soda acid type- water extinguisher through the dip tube.

  • A. hydrogen
  • B. oxygen
  • C. nitrogen
  • D. carbon-dioxid
Answer: D — carbon-dioxid
Soda-acid fire extinguishers use a solution of sodium bicarbonate in water that reacts with sulfuric acid to generate carbon dioxide expellant gas for Class A fires.

2. Good housekeeping on a vessel prevents fires by

  • A. allowing better access in an emergency
  • B. eliminating potential fuel sources
  • C. eliminating trip hazards
  • D. improving personnel qualifications
Answer: B — eliminating potential fuel sources
The correct answer is eliminating potential fuel sources. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

3. On each LNG cargo tank two relief valves are fitted. Identify the correct combination of "set pressure" (lifting pressure) and "reseating pressure" for these valves.

  • A. 250 mbar and 220 mbar
  • B. 50 mbar and 20 mbar
  • C. 2.5 bar and 2.2 bar
  • D. 500 mbar and 200 mbar
Answer: A — 250 mbar and 220 mbar
The correct answer is 250 mbar and 220 mbar. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

4. Advantages of reliquefaction plant on LNG tankships will not include,

  • A. Total quantity of LNG loaded can be delivered to the customer
  • B. Reduction in heel required on ballast voyag
  • C. Lower S0 and NO emissions
  • D. Proven technology and easy availability of crew
Answer: C — Lower S0 and NO emissions
The correct answer is Lower S0 and NO emissions. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

5. What happens to the air leaving drying tower if the activated alumina inside cylindrical alumina inside cylindrical tank is "old" (inefficient)?

  • A. It will not be at required dew point
  • B. It will not be affected at all
  • C. It will not be warm enough
  • D. It will not be cold enough
Answer: A — It will not be at required dew point
The correct answer is It will not be at required dew point. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

6. What is provided to ensure that the low duty gas compressor flow rate does not fall below the designed minimum?

  • A. An automatic shut down system
  • B. An automatic surge control system
  • C. An automatic venting system
  • D. An automatic start system
Answer: B — An automatic surge control system
A nitrogen seal gas system is fitted on LNG boil-off gas compressors to prevent lubricating oil mist from contaminating the compressed vapor and prevent gas leakage along shaft seals.

7. Onboard an LNG Tanker, while vaporizing during cargo discharge using the main vaporizer, what is the approximate desired outlet temperature of LNG vapour?

  • A. -140°C
  • B. -130°C
  • C. -10°C
  • D. -120°C
Answer: C — -10°C
The correct answer is -10°C. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

8. There are typically two types of gas heaters onboard an LNG tanker. One is the main heater and which of the following options is the other?

  • A. IG heater
  • B. Fuel gas heater (Boil - off gas heater)
  • C. Nitrogen heater
  • D. Air heater
Answer: B — Fuel gas heater (Boil - off gas heater)
The correct answer is Fuel gas heater (Boil - off gas heater). This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

9. A typical membrane method Nitrogen Generator's Air Compressor will trip when the following occur, EXCEPT

  • A. Nitrogen storage tank pressuree high
  • B. Air Compressor oil separator pressuree high
  • C. Air Compressor oil separator inlet temperature high
  • D. Air Compressor oxygen reading 20% by volum
Answer: D — Air Compressor oxygen reading 20% by volum
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

10. The following are the communication connection integrated in the ESDS fibre optic system, EXCEPT:

  • A. 1 connection satellite telephon
  • B. 1 hotline telephone (to terminal)
  • C. 1 public telephon
  • D. 1 normal telephone (to terminal)
Answer: A — 1 connection satellite telephon
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.

11. What is the purpose of having a level gauging system?

  • A. To avoid over pressureizing of cargo tanks during loading operation
  • B. To ensure tank cool down rate is maintained at required rat
  • C. To get accurate tank levels for custody transfer and topping up
  • D. To prevent sudden temperature change in the insulation spaces
Answer: C — To get accurate tank levels for custody transfer and topping up
The correct answer is To get accurate tank levels for custody transfer and topping up. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

12. What is the type of gas detection system fitted for spaces with air?

  • A. Spot metering type fixed inside the individual insulation spaces
  • B. Infrared type using sequential measurement
  • C. Portable gas detection system due to mobility of this method
  • D. Catalytic combustion typ
Answer: A — Spot metering type fixed inside the individual insulation spaces
The correct answer is Spot metering type fixed inside the individual insulation spaces. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

13. What is the "ESDS" abbreviation stands for?

  • A. Emergency shutdown deck system
  • B. Emergency system deck serial
  • C. Emergency shutdown system
  • D. Emergency downtime system
Answer: C — Emergency shutdown system
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.

14. How many suitable and operational portable gas detection equipment shall be available onboard?

  • A. At least two sets with methane gas detection capability
  • B. At least one with methane and one of carbon monoxides gas detection capability
  • C. At least one with methane gas and one of Ammonia gas detection capability
  • D. At least one with methane gas and one of propane gas detection capability
Answer: A — At least two sets with methane gas detection capability
The correct answer is At least two sets with methane gas detection capability. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

15. What is the type of gas detection system fitted to monitor gas content of the insulation spaces?

  • A. Continuous measurement system using catalytic combustion typ
  • B. Infrared type / sequential measurement
  • C. Portable gas detection system due to mobility of this method
  • D. Spot metering type fixed inside the individual insulation spaces
Answer: B — Infrared type / sequential measurement
The correct answer is Infrared type / sequential measurement. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

16. What is the use of a Distributed Control System (DCS) onboard an LNG carrier?

  • A. To allow the shore to control the ship's system from the terminal cargo control room
  • B. To monitor and control main propulsion and cargo operations
  • C. To monitor and control various cargo equipment distributed on the deck
  • D. To monitor and control the shore valves from the ship's carao control room
Answer: B — To monitor and control main propulsion and cargo operations
The correct answer is To monitor and control main propulsion and cargo operations. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

17. Which of the following is not a sign of an LNG gas (vapor) leak into insulation spaces?

  • A. Comparing to normal trends - high temperature variations on barrier spaces
  • B. Increase of pressuree in insulation spaces
  • C. Icing of sea water outside hull when ship at anchor
  • D. Sudden rise in percentage of methane vapour in insulation spaces
Answer: C — Icing of sea water outside hull when ship at anchor
The correct answer is Icing of sea water outside hull when ship at anchor. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

18. How is intrinsic safety achieved for electrical circuits used in hazardous areas?

  • A. By limiting the ignition energy and surface temperature that can arise during operation
  • B. By increasing mechanical ventilation to the area
  • C. By limiting the number of equipment used in a spac
  • D. By installing machinery which have higher power and thus shorter operation tim
Answer: A — By limiting the ignition energy and surface temperature that can arise during operation
The correct answer is By limiting the ignition energy and surface temperature that can arise during operation. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

19. Why is the 'maximum surface temperature' identified, for electrical equipment used in hazardous areas onboard LNG carriers?

  • A. The limit is on minimum surface temperature on LNG carriers as the cargo is cryogenic
  • B. Equipment should operate within these limits to prevent the formation of a hot surfac
  • C. Equipment should operate within these limits to reduce the power and boil-off consumption
  • D. Equipment should operate within these limits to reduce the heat transfer to the cryogenic cargo
Answer: B — Equipment should operate within these limits to prevent the formation of a hot surfac
The correct answer is Equipment should operate within these limits to prevent the formation of a hot surfac. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

20. What can major failure of primary membrane lead to?

  • A. Flooding of primary insulation space by cargo
  • B. Increase of temperature in pirmary spaces
  • C. Decrease of gas content in the primary space readings
  • D. Increase of gas content in secondary spac
Answer: A — Flooding of primary insulation space by cargo
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

21. How will you measure methane concentration inside insulation spaces?

  • A. By using hydrocarbon meter
  • B. By using hydrometer
  • C. By using personnel oxygen meter
  • D. By using tank scop
Answer: A — By using hydrocarbon meter
The correct answer is By using hydrocarbon meter. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

22. For the LNG NO 96 containment system, why is the cargo tanks secondary insulation spaces pressure maintained slightly higher than primary insulation spaces?

  • A. To avoid vapor transfer into secondary insulation spaces if primary insulation spaces vapor leaks
  • B. To avoid cold spot formation in inner hull
  • C. To reduce heat transfer and increase efficiency of insulation spaces
  • D. To prevent ingress of air through the leak spot into cargo tank
Answer: A — To avoid vapor transfer into secondary insulation spaces if primary insulation spaces vapor leaks
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

23. How do you remove water from the secondary insulation space?

  • A. By using emergency turbine driven pump fitted in secondary insulation spaces well
  • B. By using vacuum pump fitted inside compressor room
  • C. By using emergency cargo pump fitted in affected tank emergency cargo pump column
  • D. By using emergency hand driven pump fitted in primary insulation spaces well
Answer: A — By using emergency turbine driven pump fitted in secondary insulation spaces well
The correct answer is By using emergency turbine driven pump fitted in secondary insulation spaces well. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

24. If insulation damage occurs, how does filling the ballast tanks with sea water help in maintaining the hull steel temperature?

  • A. Through slow heat transfer, as sea water conducts heat better than air
  • B. Through better heat transfer, as sea water conducts heat better than air
  • C. Due to the improved heat transfer to outside sea at ambient temperatur
  • D. As sea water temperature is much lower than LNG temperature, thus helping the heat transfer
Answer: B — Through better heat transfer, as sea water conducts heat better than air
The correct answer is Through better heat transfer, as sea water conducts heat better than air. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

25. Onboard an LNG tanker with NO 96 containment system, what will happen if a minor membrane leak (crack) occurs above the cargo level?

  • A. Small flow of liquid into the crack will vaporize. cargo tank pressuree will remain the same.
  • B. Direct vapor flow rate into the insulation spaces via the crack changes with cargo tank's pressure
  • C. Cargo pressuree will be tremendously increased boil-off Gas will be out of control
  • D. Leak will become bigger and primary membranee will collapse inwards
Answer: B — Direct vapor flow rate into the insulation spaces via the crack changes with cargo tank's pressure
In Gaztransport & Technigaz NO 96 membrane containment systems, Invar membranes and perlite insulation boxes maintain cargo containment and thermal insulation.

26. International Certificate of fitness for Carriage of Liquefied Gas in bulk will not include,

  • A. signify that a minimum standard of constructional safety has been incorporated into the ship's build
  • B. list the cargo grades that the ship is certified to carry
  • C. the carriage condition or minimum tank temperature that must be maintained
  • D. the carriage condition for minimum certificated crew that must be maintained.
Answer: D — the carriage condition for minimum certificated crew that must be maintained.
The correct answer is the carriage condition for minimum certificated crew that must be maintained.. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

27. Which code will you refer to for the requirements on LNG containment system?

  • A. SIGTTO
  • B. IGC Cod
  • C. IBC Cod
  • D. OCIMF
Answer: B — IGC Cod
The correct answer is IGC Cod. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

28. What is the ideal location for the cargo tank from the bottom shell plating, for any Gas Tanker type?

  • A. B/ 10 or 1.5 meters (4.9 feet), whichever is less
  • B. B/5 or 3.0 meters (9.8 feet), whichever is less
  • C. B/ 15 or 2 meters (6.5 feet), whichever isless
  • D. B/ 4 or 2.4 meters (7.9 feet), whichever is less
Answer: C — B/ 15 or 2 meters (6.5 feet), whichever isless
The correct answer is B/ 15 or 2 meters (6.5 feet), whichever isless. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

29. As per Chapter 11 of IGC code (fire protection and fire extinction) which of the following is a requirement for an LNG tanker?

  • A. Firemen's outfits
  • B. Fire ESD system
  • C. Fire emergency response plans
  • D. Fire equipment test / drill
Answer: A — Firemen's outfits
Fixed water spray systems on gas carriers provide boundary cooling for cargo tank domes, deck piping, manifolds, and accommodation forward bulkheads.

30. Onboard an LNG carrier, what provisions are made for separation between the deck and electric motors room?

  • A. Watertight doors
  • B. Airlocks
  • C. Air intakes
  • D. Weathertight doors
Answer: B — Airlocks
The correct answer is Airlocks. This complies with established gas tanker operational standards, thermodynamics, and the IGC Code safety requirements.

Printing this? Use your browser's Print (Ctrl/⌘ + P) — the buttons, the search box and the site chrome drop out and the questions run on as plain text, so a set fits a few pages. Filter to one set first if you only want that set on paper.

Practise these GASCO questions as a timed paper All 351 GASCO questions and answers GASCO exit exam sets and syllabus All 27 STCW exit exam courses