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BIGF exit exam questions and answers — Set 6 — Basic Training for Ships subject to the IGF Code

Set 6 of the Basic Training for Ships subject to the IGF Code (BIGF) exit exam bank — 30 of 429 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 6 — 30 BIGF exit exam questions with answers

1. Flammable range is the range of concentrations between

  • A. lower flammable limit
  • B. upper flammablle limit
  • C. none of the above
  • D. both (a) and (b)
Answer: D — both (a) and (b)
The flammable range is defined by the interval between the Lower Flammable Limit (LFL/LEL) and the Upper Flammable Limit (UFL/UEL).

2. Flash point is the ________ temperature at which a liquid gives off sufficient vapour to form a flammable mixture with air near the surface of the liquid.

  • A. zero
  • B. lowest
  • C. highest
  • D. medium
Answer: B — lowest
The flash point is the lowest liquid temperature at which sufficient vapor is evolved to form an ignitable flammable mixture with air near the liquid surface.

3. Gas code are ______________carrying liquefied gases in bulk

  • A. equipment of ships
  • B. none of the above
  • C. both (a) and (b)
  • D. codes of construction
Answer: C — both (a) and (b)
The IMO Gas Codes (GC Code, IGC Code, IGF Code) provide international safety standards for ships carrying liquefied gases in bulk or using gases as fuel.

4. Gas codes are published by ____________

  • A. Indian Marine Organisation
  • B. International Marine Oraganisation
  • C. International Maritime Oraganisation
  • D. Indian Maritime Organisation
Answer: C — International Maritime Oraganisation
The International Gas Codes (IGC Code, IGF Code) are developed, updated, and published by the International Maritime Organization (IMO).

5. ___________ is within ship's cargo area which is designated as likely to contain flammable vapour

  • A. Gas dangerous zone
  • B. both (a) and (b)
  • C. none of the above
  • D. Gas dangerous space
Answer: B — both (a) and (b)
A hazardous area is a designated zone on board ship within which a flammable gas atmosphere is expected to be present in quantities requiring specialized electrical equipment and precautions.

6. What does gas free certificate certified for?

  • A. 21 percent nitrogen by volume
  • B. 21 percent carbon dioxide by volume
  • C. 21 percent hydrogen by volume
  • D. 21 percent oxygen by volume
Answer: D — 21 percent oxygen by volume
A standard Gas Free Certificate confirms that an enclosed space contains 20.9% to 21% oxygen by volume, 0% LEL of flammable vapors, and safe toxic gas limits.

7. When is gas free certificate issued?

  • A. considered safe for surrounding hot work
  • B. tank hs been suitably inerted
  • C. both (a) and (b)
  • D. none of the above
Answer: C — both (a) and (b)
A Gas Free Certificate is issued by a certified marine chemist or authorized safety officer prior to hot work or shipyard drydock operations.

8. What is Gas freeing?

  • A. All of the above
  • B. removal of inert gas from a tank
  • C. removal of flammable gas from a tank
  • D. removal of toxic gas from a tank
Answer: A — All of the above
Gas freeing is the process of displacing inert gas or cargo vapors from tanks and void spaces using fresh air until the atmosphere is non-toxic, non-flammable, and breathable.

9. What is latent heat of vaporization?

  • A. permitting the outward passage of gas
  • B. sufficiently free from chemical
  • C. sufficiently free from hydrocarbon gases
  • D. Quality of heat to change the state of a substance from liquid to vapour without change of temperature
Answer: D — Quality of heat to change the state of a substance from liquid to vapour without change of temperature
Latent heat of vaporization is the amount of heat energy required to transform a unit mass of liquid into vapor at its boiling point without any change in temperature.

10. In latent heat of vaporization, Quality of heat to change the state of a substance from ____________ without change of temperature

  • A. solid to liquid
  • B. solid to vapour
  • C. liquid to molecules
  • D. liquid to vapour
Answer: D — liquid to vapour
Latent heat of vaporization measures the thermal energy required to change a substance's physical phase from liquid to vapor at constant temperature and pressure.

11. What is Liquefied gas?

  • A. sufficiently free from hydrocarbon gases
  • B. liquid which has a saturated vapour pressure exceeding 2.8 bar absolute at 37.80C and certain other substances specified in the Gas Codes
  • C. Quality of heat to change the state of a substance from liquid to vapour without change of temperature
  • D. permitting the outward passage of gas
Answer: B — liquid which has a saturated vapour pressure exceeding 2.8 bar absolute at 37.80C and certain other substances specified in the Gas Codes
The IMO Gas Codes define a liquefied gas as any liquid having a saturated vapor pressure exceeding 2.8 bar absolute at a temperature of 37.8°C.

12. In Liquefied gas, a liquid which has a saturated vapour pressure exceeding ______ absolute at 37.80C and certain other substances specified in the Gas Codes.

  • A. 18 bar
  • B. 308 bar
  • C. 48 bar
  • D. 2.8 bar
Answer: D — 2.8 bar
Liquefied gases are legally defined by a saturated vapor pressure exceeding 2.8 bar absolute at 37.8°C under the IMO IGC and IGF Codes.

13. In Liquefied gas, a liquid which has a saturated vapour pressure exceeding 2.8 bar absolute at __________ and certain other substances specified in the Gas Codes.

  • A. none of the above
  • B. 0
  • C. 100
  • D. 37.80C
Answer: D — 37.80C
The standard reference temperature at which the 2.8 bar absolute vapor pressure threshold is measured under the IMO Gas Codes is 37.8°C (100°F).

14. In Liquefied gas, a liquid which has a saturated vapour pressure __________ 2.8 bar absolute at 37.80C and certain other substances specified in the Gas Codes.

  • A. none of the above
  • B. maintaining
  • C. decreasing
  • D. exceeding
Answer: D — exceeding
Under the IMO Gas Codes, a cargo is classified as a liquefied gas when its saturated vapor pressure exceeds 2.8 bar absolute at 37.8°C.

15. What is the major constituent of Liquefied Natural Gas?

  • A. Polybutadiene
  • B. Styrene
  • C. methane
  • D. Acrylonitrile
Answer: C — methane
Methane (CH4) is the predominant hydrocarbon constituent of Liquefied Natural Gas (LNG), typically comprising 85% to 99% of its composition.

16. What is lower flamable limit?

  • A. The concentration of a hydrocarbon gas in air below which there is insufficient hydrocarbon to support combustion.
  • B. The concentration of a carbon gas in air below which there is insufficient hydrocarbon to support combustion.
  • C. The concentration of a hydrogen gas in air below which there is insufficient hydrocarbon to support combustion.
  • D. The concentration of a nitrocarbon gas in air below which there is insufficient hydrocarbon to support combustion.
Answer: A — The concentration of a hydrocarbon gas in air below which there is insufficient hydrocarbon to support combustion.
The Lower Flammable Limit (LFL) is the minimum concentration of flammable vapor in air below which the mixture is too lean to ignite or sustain combustion.

17. What is concentration of a hydrocarbon gas in air below which there is insufficient hydrocarbon to support combustion?

  • A. Flash point
  • B. Gas freeing
  • C. Flammable range
  • D. Lower flamable limit
Answer: D — Lower flamable limit
The Lower Flammable Limit (LFL/LEL) represents the minimum volume percentage of fuel vapor in air required to support combustion; below this level the fuel mixture is too lean.

18. Accidental release measures in an MSDS will NOT include ____.

  • A. Personal precautions, protective equipment and emergency procedures
  • B. Methods and materials for containment and cleaning up
  • C. Environmental precautions
  • D. Instructions for informing the authorities of an accidental release
Answer: D — Instructions for informing the authorities of an accidental release
Section 6 of a GHS-format SDS (accidental release measures) covers personal precautions, protective equipment and emergency procedures, environmental precautions, and methods and materials for containment and clean-up. Reporting obligations come from regulations and company procedures, not this section.

19. Which flammability diagram is used to follow changes in the cargo tank atmosphere on an LNG 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
During inerting, gassing up and aeration, the tank atmosphere is a mixture of methane, oxygen and nitrogen. The methane-oxygen-nitrogen flammability diagram shows whether the mixture stays outside the flammable zone during these changes.

20. Which of the following cargoes carries a risk of polymerisation?

  • A. Methane
  • B. Propane
  • C. Butane
  • D. Vinyl chloride
Answer: D — Vinyl chloride
Vinyl chloride monomer can polymerise exothermically, so it is carried with an inhibitor or under an oxygen-free inert atmosphere, as required by the IGC Code. Methane, propane and butane are saturated hydrocarbons and do not polymerise.

21. Ethylene carriers normally use ____.

  • A. Semi-pressurised and refrigerated tanks
  • B. Semi-pressurised and non-refrigerated tanks
  • C. Pressurised and non-refrigerated tanks
  • D. None of these
Answer: A — Semi-pressurised and refrigerated tanks
Ethylene boils at about -104°C and its critical temperature is about 9.5°C, so it cannot be kept liquid by pressure alone at ambient temperature. Ethylene carriers use insulated semi-pressurised/fully refrigerated tanks with cascade reliquefaction plants.

22. In relation to a ship's boiler, identify the INCORRECT statement.

  • A. Radiant heat absorbed by the heating surface is passed by conduction to the water inside the tubes
  • B. Convection currents in the water complete the transfer of heat from the burning fuel to the water
  • C. Radiation, conduction and convection do not all occur in the boiler at the same time
  • D. The amount and arrangement of heating surface determine the size, shape and form of the boiler
Answer: C — Radiation, conduction and convection do not all occur in the boiler at the same time
In a boiler all three modes of heat transfer happen at once. The flame radiates to the tubes, heat is conducted through the metal, and convection carries it in the water and in the flue gases. The claim that they do not occur together is false.

23. A vessel loads ammonia and obtains the MSDS from the shipper. Which of the following information is given in the MSDS?

  • A. A synonym of ammonia is marsh gas
  • B. The main hazards of ammonia are toxicity and corrosivity
  • C. The main hazard of ammonia is flammability
  • D. The chemical formula of ammonia is CH4
Answer: B — The main hazards of ammonia are toxicity and corrosivity
Anhydrous ammonia (NH3) is classed mainly as toxic and corrosive. It is flammable only within a narrow range of about 15 to 28%, so this hazard is secondary. Marsh gas and CH4 refer to methane.

24. Which law states that the total pressure of a gas mixture equals the sum of the partial pressures of its constituent gases?

  • A. Boyle's law
  • B. Charles's law
  • C. Gay-Lussac's law
  • D. Dalton's law of partial pressures
Answer: D — Dalton's law of partial pressures
Dalton's law states that in a mixture of non-reacting gases, each gas exerts the pressure it would exert alone, and the total pressure is the sum of these partial pressures. This is the basis for working out vapour concentration in a tank atmosphere.

25. The outlet from a fuel tank pressure relief valve shall normally be located at least ____ from the nearest air intake, air outlet or opening to accommodation, service and control spaces.

  • A. 5 m
  • B. 10 m
  • C. 12 m
  • D. 15 m
Answer: B — 10 m
The IGF Code (and similarly the IGC Code) requires vent outlets from pressure relief valves to be at least 10 m from the nearest air intake, air outlet or opening to accommodation, service and control spaces or other non-hazardous areas.

26. The sum of gauge pressure and atmospheric pressure is ____.

  • A. Absolute pressure
  • B. Vacuum pressure
  • C. Atmospheric pressure
  • D. Critical pressure
Answer: A — Absolute pressure
Gauge pressure is measured relative to the surrounding atmosphere. Adding atmospheric pressure, about 1.013 bar, gives absolute pressure, which is used in gas laws and on vapour pressure curves.

27. A tank that receives liquid overflowing from a full tank is called a(n) ____.

  • A. Overflow tank
  • B. Spilling tank
  • C. Flowing tank
  • D. None of these
Answer: A — Overflow tank
An overflow tank collects liquid that overflows from service, settling or storage tanks through overflow pipes, so the liquid does not spill on deck or into the machinery space. Its level is alarmed.

28. ____ is the standard atmospheric pressure, equivalent to 760 mm (29.92 inches) of mercury.

  • A. 913.25 millibars
  • B. 1013.25 millibars
  • C. 1213.25 millibars
  • D. None of these
Answer: B — 1013.25 millibars
One standard atmosphere is 760 mmHg, or 29.92 inHg, equal to 1013.25 millibars (hPa) or 101.325 kPa. It is the reference for converting between gauge and absolute pressure.

29. What method is used on board LNG carriers for replacing gases in cargo tanks?

  • A. Displacement method
  • B. Dilution by repeated pressurisation
  • C. Dilution by repeated vacuum
  • D. Continuous dilution
Answer: A — Displacement method
LNG carriers usually change tank atmospheres by displacement, or the piston effect. A gas of different density is introduced slowly at the top or bottom so it pushes the existing gas out with little mixing, which saves inert gas and time.

30. Identify the correct sequence of tank preparation before bunkering (or loading) LNG.

  • A. Purging, inerting and cool-down
  • B. Inerting, gassing up and cool-down
  • C. Cool-down, purging and gassing up
  • D. Gassing up, inerting and cool-down
Answer: B — Inerting, gassing up and cool-down
An aerated tank is first inerted to bring oxygen down, then gassed up with natural gas vapour to remove the inert gas and CO2 that would freeze, and finally cooled down gradually before liquid is loaded.

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