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

All 429 questions from the Basic Training for Ships subject to the IGF Code (BIGF) exit exam bank, 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 13 Oct 2026.

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

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Set 1 — 30 BIGF exit exam questions with answers

1. IMO means ____________

A. International Main Oraganisation
B. Indian Marine Organisation
C. International Maritime Oraganisation
D. Indian Maritime Organisation

Answer: C — International Maritime Oraganisation

IMO stands for International Maritime Organization, the specialized agency of the United Nations responsible for regulating shipping safety, maritime security, and marine environmental protection.

2. A liquefied gas is the liquid form of a substance, which at _________________would be a gas.

A. both (a) and (b)
B. ambient temperature
C. none of the above
D. atmospheric pressure

Answer: A — both (a) and (b)

A liquefied gas is defined by the Gas Codes as the liquid form of a substance which, at ambient temperature and atmospheric pressure, would exist in a gaseous state.

3. The most important property of a liquified gas, in relation to pumping and storage is _____________

A. none of the above
B. low vapour pressure
C. high vapour pressure
D. saturated vapour pressure

Answer: D — saturated vapour pressure

Saturated Vapor Pressure (SVP) is the most critical physical property of a liquefied gas regarding pumping, storage, and tank pressure management.

4. Saturated vapour pressure is the ___________ pressure exerted when liquid is in equlibrium with its own vapour at a given temperature.

A. flexible
B. partial
C. relative
D. absolute

Answer: D — absolute

Saturated vapor pressure is the absolute pressure exerted by a vapor in thermodynamic equilibrium with its liquid phase at a given temperature in a closed system.

5. The most important property of a liquified gas, in relation to ___________ is saturated vapour pressure

A. storage
B. both (a) and (b)
C. pumping
D. none of the above

Answer: B — both (a) and (b)

Saturated vapor pressure directly governs both cargo pumping cavitation limits and fuel tank pressure containment requirements for liquefied gases.

6. Saturated vapour pressure is the absolute pressure exerted when _______ is in equlibrium with its own vapour at a given temperature.

A. vapour
B. liquid
C. solid
D. gas

Answer: B — liquid

Saturated vapor pressure is the absolute equilibrium pressure exerted by the evaporated vapor above the liquid surface at a specified temperature.

7. Saturated vapour pressure is the absolute pressure exerted when liquid is in ___________ with its own vapour at a given temperature.

A. none of the above
B. equlibrium
C. stability
D. tranquility

Answer: B — equlibrium

Thermodynamic equilibrium occurs when the rate of liquid evaporation equals the rate of vapor condensation at a constant temperature and pressure.

8. Liquid with a vapour pressure exceeding ________absolute at a temperature of 37.8 deg C.

A. 2.0 bar
B. 2.9 bar
C. 2.5 bar
D. 2.8 bar

Answer: D — 2.8 bar

Under the IMO IGC and IGF Codes, a liquefied gas is defined as a liquid having a saturated vapor pressure exceeding 2.8 bar absolute at a temperature of 37.8°C.

9. Liquid with a vapour pressure exceeding 2.8 bar absolute at a temperature of __________.

A. 38.8 deg C
B. 37.8 deg C
C. 36.8 deg C
D. 37.0 deg C

Answer: B — 37.8 deg C

The standard reference temperature defined in the IMO Gas Codes for classifying liquefied gases by vapor pressure (exceeding 2.8 bar absolute) is 37.8°C (100°F).

10. What are the cargoes carried on Liquified Gas Tankers?

A. Liquified Petroleum Gas
B. none of the above
C. Liquified Natural Gas
D. both (a) and (b)

Answer: D — both (a) and (b)

Liquefied gas tankers carry both Liquefied Petroleum Gas (propane and butane) and Liquefied Natural Gas (mainly methane), as well as chemical gases such as ammonia and ethylene listed in the IGC Code.

11. ____________ is transported either by pipeline as a gas or by sea in its liquified form as Liquified Natural Gas.

A. Natural gas
B. Ethane gas
C. Chemical gases
D. none of the above

Answer: A — Natural gas

Natural gas is transported either overland via pressurized pipeline grids or across oceans by specialized gas carriers in liquefied form as Liquefied Natural Gas (LNG).

12. Natural gas comes from ________________

A. heating mixtures
B. rocks
C. cold climate
D. underground deposits

Answer: D — underground deposits

Natural gas is a naturally occurring fossil fuel extracted from underground geological hydrocarbon reservoirs and gas fields.

13. In natural gas what is the range of methane ?

A. 50%
B. 70 to 99 %
C. 100%
D. 60 to 88%

Answer: B — 70 to 99 %

Methane (CH4) is the predominant component of raw and commercial natural gas, typically comprising 70% to 99% of the total gas volume.

14. Which is the major constituent of natural gas?

A. oxygen
B. ethane
C. methane
D. octane

Answer: C — methane

Methane is the lightest and primary constituent of natural gas, typically making up between 85% and 95%+ of Liquefied Natural Gas.

15. Methane is a petrochemical stock leading to the production of _________

A. acetic acid
B. acetaldehyde
C. methonal
D. ethanol

Answer: C — methonal

Methane is an essential petrochemical feedstock used in chemical synthesis plants for the commercial production of methanol and ammonia.

16. ____________ is a petrochemical stock leading to the production of methonal

A. Octane
B. Methane
C. Acetic acid
D. Ethane

Answer: B — Methane

Methane is reacted with steam (steam reforming) to produce synthesis gas, which is the primary feedstock for manufacturing methanol.

17. Methanol is a feedstock to ___________

A. both (a) and (b)
B. none of the above
C. Methyl tetra chloride
D. Formaldehyde

Answer: A — both (a) and (b)

Methanol is a versatile petrochemical intermediate widely used in the production of formaldehyde, acetic acid, solvents, and alternative marine fuels.

18. Associated gas found in combination with __________ comprises mainly methane and Natural Gas Liquids

A. gas
B. crude oil
C. diesel
D. petroluem

Answer: B — crude oil

Associated gas is natural gas found in reservoir contact with crude oil, containing methane along with heavier Natural Gas Liquids (NGLs).

19. Associated gas found in combination with crude oil comprises mainly ______________

A. none of the above
B. methane
C. both (a) and (b)
D. Natural Gas Liquids

Answer: C — both (a) and (b)

Associated petroleum gas consists of a mixture of methane and heavier fractions known as Natural Gas Liquids (ethane, propane, butane, pentane).

20. Natural Gas Liquids are made up of __________

A. Liquified Petroleum Gas
B. none of the above
C. ethane
D. both (a) and (b)

Answer: D — both (a) and (b)

Natural Gas Liquids (NGL) comprise the heavier hydrocarbon fractions of natural gas, primarily ethane, propane, butane, isobutane, and natural gasoline.

21. Natural Gas Liquids are carried at- _________ at atmospheric pressure

A. 37oC
B. 35oC
C. 36oC
D. 80oC

Answer: D — 80oC

Heavier Natural Gas Liquid fractions can be refrigerated and carried as liquids at temperatures down to -80°C at atmospheric pressure.

22. Natural Gas Liquids are carried at- _________ at atmospheric vapour pressure of 5 bar

A. 135degc
B. 400degC
C. 45degc
D. 550degc

Answer: C — 45degc

Semi-pressurized carriage allows certain liquefied gas fractions to be transported at temperatures around -45°C under a vapor pressure of approximately 5 bar.

23. Natural Gas Liquids are carried at -45deg C at vapour pressure of __________

A. 15 bar
B. 7 bar
C. 5 bar
D. 25 bar

Answer: C — 5 bar

Carriage of liquefied petroleum gases in semi-refrigerated tanks is commonly maintained at -45°C with a designed working vapor pressure of about 5 bar.

24. Liquified Petroleum Gas is a comprise of ________________

A. propane
B. none of the above
C. butane
D. both (a) and (b)

Answer: D — both (a) and (b)

Liquefied Petroleum Gas (LPG) consists primarily of propane (C3H8), butane (C4H10), or commercial mixtures of both hydrocarbons.

25. What is the use of bottled gas?

A. none of the above
B. both (a) and (b)
C. cooking in remote loctions
D. fuel for heating

Answer: B — both (a) and (b)

Commercial bottled gas (LPG cylinders) is widely utilized for domestic heating, commercial cooking, automotive fuel (autogas), and industrial cutting.

26. Which is an important octane enhancer for motor gasoline?

A. kerosene
B. crude oil
C. water
D. butane

Answer: D — butane

Commercial butane and isobutane are critical blending agents and octane enhancers utilized in the refining of motor gasoline.

27. Which is used as bottled gas in cold climates?

A. ammonia
B. both (a) and (b)
C. propane
D. none of the above

Answer: C — propane

Propane has a lower boiling point (-42°C) than butane (-0.5°C), allowing it to vaporize easily and serve as bottled gas in cold climates.

28. Liquified Petroleum Gas is mainly used in ________

A. power generation
B. All of the above
C. petrochemical feedstock
D. metal cutting

Answer: B — All of the above

LPG is utilized globally as domestic cooking fuel, industrial heating fuel, automotive autogas, and as petrochemical cracker feed.

29. Used as Petrochemical feedstock for the production of ________

A. both (a) and (b)
B. none of the above
C. acetic acid
D. acetaldehyde

Answer: A — both (a) and (b)

LPG fractions (propane and butane) are vital petrochemical feedstocks for steam cracking into olefins like ethylene and propylene.

30. ____________ accounts the large for the third largest sea borne trade in liquified gases after Liquified Natural Gas and Liquified Petroleum Gas

A. Urea
B. Ammonia
C. both (a) and (b)
D. none of the above

Answer: B — Ammonia

Anhydrous ammonia (NH3) represents the third largest seaborne trade volume among liquefied gases, following LNG and LPG, primarily used for agricultural fertilizers.

Set 2 — 30 BIGF exit exam questions with answers

1. _________ is the primary petrochemical building blocks

A. kerosene
B. none of the above
C. Ethylene
D. chlorine

Answer: C — Ethylene

Ethylene (C2H4) is the world's primary organic chemical building block, serving as the base precursor for polyethylene plastics, ethylene glycol, and vinyls.

2. Products obatined from ethylene are

A. polyethylene
B. polyvinyl chloride
C. All of the above
D. rubber

Answer: C — All of the above

Ethylene is the primary precursor for polyethylene (HDPE, LDPE), ethylene dichloride (EDC for PVC), ethylene oxide, and synthetic alcohols.

3. Propylene is a petrochemical intermediate used to make which product

A. All of the above
B. Acetone
C. Phenol
D. Detergent

Answer: A — All of the above

Propylene is a key chemical intermediate used to synthesize polypropylene plastics, acrylonitrile (acrylic fibers), propylene oxide, and cumene.

4. Butadiene is a _______________ petrochemical intermediaste.

A. medium reactive
B. none of the above
C. high reactive
D. low reactive

Answer: C — high reactive

1,3-Butadiene is a highly reactive, flammable conjugated diene petrochemical intermediate that requires polymerization inhibitors during marine transport.

5. Butadiene is used in

A. binders
B. intermediate in plastics
C. paints
D. All of the above

Answer: D — All of the above

Butadiene is primarily utilized in the production of synthetic elastomers, styrene-butadiene rubber (SBR) for vehicle tires, and ABS engineering plastics.

6. What are the products from Butadiene?

A. Synthetic rubbers
B. Polybutadiene
C. All of the above
D. Styrene

Answer: C — All of the above

Key industrial end-products derived from butadiene include polybutadiene rubber, nitrile rubber (NBR), neoprene, and nylon intermediates.

7. Vinyl Chloride is an easily ___________ used in the manufacture of polyvinyl chloride

A. chlorinated gas
B. none of the above
C. liquefiable
D. both (a) and (b)

Answer: D — both (a) and (b)

Vinyl Chloride Monomer (VCM) is a chlorinated gas that is readily liquefied under mild pressure or refrigeration, used to manufacture polyvinyl chloride (PVC).

8. _______________ is an easily liquefiable and chlorinated gas used in the manufacture of polyvinyl chloride

A. oxygen
B. none of the above
C. florine
D. Vinyl Chloride

Answer: D — Vinyl Chloride

Vinyl Chloride Monomer (VCM) is an organochloride gas essential to the global plastics industry for manufacturing PVC pipes and construction materials.

9. Vinyl Chloride has a ____________ boiling point at - 14 deg C.

A. high
B. low
C. zero
D. medium

Answer: A — high

Vinyl Chloride Monomer has an atmospheric boiling point of -13.8°C (approx. -14°C), allowing it to be transported in semi-pressurized or fully refrigerated gas carriers.

10. Vinyl Chloride has a ____________specific gravity much denser than other common gas.

A. 0.67
B. 0.87
C. 0.57
D. 0.97

Answer: D — 0.97

Vinyl Chloride Monomer vapor has a high liquid specific gravity (approx. 0.97 at boiling point) and a heavy vapor density (2.15 times heavier than air).

11. Gas shipping began in which year?

A. 1920
B. 2000
C. 1520
D. 2019

Answer: A — 1920

Gas shipping began in the late 1920s, when the first ships were fitted to carry liquefied petroleum gas in pressure vessels. The trade grew after the first LNG carriers appeared in the late 1950s.

12. In which year fully refrigerated ships for Liquified Petroleum Gas, Liquified Natural Gas and certain chemical gases.

A. 2010
B. 2019
C. 1963
D. 1900

Answer: C — 1963

The era of modern fully refrigerated ocean-going LNG and LPG carriers began in the early 1960s with purpose-built insulated containment systems.

13. Absolute pressure is the total of ___________

A. pressure of surrounding atmosphere
B. gauge pressure
C. both (a) and (b)
D. none of the above

Answer: C — both (a) and (b)

Absolute pressure is defined as the total pressure exerted on a surface, equal to gauge pressure plus local atmospheric pressure (P_abs = P_gauge + P_atm).

14. In practical calculations for Celcius to Kelvin _____________ is added

A. 373
B. 473
C. 73
D. 273

Answer: D — 273

To convert temperatures from the Celsius scale to the absolute thermodynamic Kelvin scale, 273.15 (commonly rounded to 273) is added to the Celsius value.

15. Absolute zero is the temperature at which the volume of gas theoretically becomes _____________

A. high
B. low
C. medium
D. zero

Answer: D — zero

Absolute zero (0 Kelvin or -273.15°C) is the theoretical thermodynamic state where molecular kinetic energy reaches its minimum and gas volume theoretically extrapolates to zero.

16. Absolute zero is _____________

A. being -473.16 deg C
B. being -273.16 deg C
C. none of the above
D. being -373.16 deg C

Answer: B — being -273.16 deg C

Absolute zero corresponds to exactly -273.15°C (or -273.16°C in early thermometry definitions relative to the triple point of water).

17. Activated Alumina a desiccant medium which operates by adsorption of ___________

A. gauge pressure
B. water molecules
C. pressure of surrounding atmosphere
D. gas

Answer: B — water molecules

Activated alumina is a highly porous desiccant adsorbent used in gas carrier dehumidifiers to remove moisture by physical adsorption of water molecules.

18. Adiabatic is an ideal process undergone by a gas in which__________ occurs

A. no loss of heat
B. no gain of heat
C. both (a) and (b)
D. none of the above

Answer: C — both (a) and (b)

An adiabatic process is an idealized thermodynamic process in which no heat energy is transferred into or out of the working fluid system (Q = 0).

19. Aerating means the introduction of fresh air into a tank with the object of removing

A. toxic
B. inert gas
C. All of the above
D. flamamable

Answer: C — All of the above

Aerating or gas-freeing is the controlled introduction of fresh air into a purged cargo or fuel tank to displace inert gas and restore a safe, breathable atmosphere.

20. Aerating means _____________ the oxygen content by 21 percent by volume.

A. decreasing
B. increasing
C. maintaining
D. none of the above

Answer: B — increasing

Aerating tank spaces increases the oxygen content back to normal atmospheric levels (20.9% to 21.0% oxygen by volume) before personnel entry.

21. Air lock is used to maintain _____________ areas at a pressure differential.

A. adjacent
B. non adjacent
C. none of the above
D. opposite

Answer: A — adjacent

Air locks maintain a positive overpressure barrier between non-hazardous gas-safe spaces (such as accommodation or control rooms) and adjacent hazardous deck zones.

22. __________ is the lowest temperature to which a liquid or gas requires to be raised to cause self- sustained spontaneous combustion

A. Boiling Point
B. Absolute Zero
C. Auto-Ignition Temperature
D. Absolute Temperature

Answer: C — Auto-Ignition Temperature

Auto-ignition temperature (AIT) is the lowest temperature at which a flammable vapor-air mixture will spontaneously ignite without an external spark or flame.

23. BLEVE means

A. Boiling Liquid Expanding Vapour Explosion
B. Boiling Liquid Exploring Vapour Explosion
C. Boil-off Liquid Expanding Vapour Explosion
D. Boil-off Liquid Exploring Vapour Explosion

Answer: A — Boiling Liquid Expanding Vapour Explosion

BLEVE stands for Boiling Liquid Expanding Vapor Explosion, a catastrophic structural failure of a pressure vessel containing a superheated liquefied gas.

24. BLEVE is associated with _________of pressure vessel containing liquified gas

A. rupture
B. under fire conditions
C. none of the above
D. both (a) and (b)

Answer: D — both (a) and (b)

A BLEVE (boiling liquid expanding vapour explosion) is the rupture of a pressure vessel containing liquefied gas, typically under fire conditions when flame impinges on the vapour space and weakens the steel.

25. ___________ is the vapour produced above the surface of a boiling cargo due to evaporation.

A. BLEVE
B. Boiling Point
C. Absolute Temperature
D. Boil-off

Answer: D — Boil-off

Boil-off gas (BOG) is the continuous vapor generated above the liquid surface inside cryogenic fuel tanks due to unavoidable ambient heat ingress.

26. Boil-Off is caused by

A. none of the above
B. both (a) and (b)
C. heat ingress
D. drop in pressure

Answer: B — both (a) and (b)

Boil-off gas formation is primarily caused by heat ingress through tank insulation and changes in atmospheric or tank vapor pressure.

27. Boiling point varies with

A. drop in pressure
B. discharge pressure
C. exerted pressure
D. none of the above

Answer: C — exerted pressure

The boiling point of any pure liquid is directly dependent upon the external pressure exerted upon its liquid surface.

28. Boil-Off varies with

A. discharge pressure
B. high pressure
C. exerted pressure
D. drop in pressure

Answer: D — drop in pressure

The rate of boil-off vapor generation increases whenever there is a drop in tank pressure or an increase in thermal heat transmission into the cargo.

29. Booster pump used to

A. exerted pressure
B. increase the discharge pressure from another pump
C. high pressure
D. drop in pressure

Answer: B — increase the discharge pressure from another pump

A booster pump raises the discharge pressure of another pump, for example a cargo booster after the deepwell pumps.

30. Cargo area contains

A. cargo containment system
B. cargo pumps
C. All of the above
D. compressor rooms

Answer: C — All of the above

Under the IGC Code, the cargo area includes the cargo containment system, cargo pump rooms and compressor rooms, and the deck areas over them. All the listed spaces form part of the cargo area.

Set 3 — 30 BIGF exit exam questions with answers

1. Cargo containment system is the arrangement for containment of cargo including where fitted with

A. primary barriers
B. associated insulations
C. secondary barriers
D. All of the above

Answer: D — All of the above

IGC Code 1.2: the cargo containment system includes primary and secondary barriers (where fitted), associated insulation and intervening spaces.

2. ______________ is the process in which vapour boil- off from acrgo tanks is condensed in a cargo condenser in which the coolant is a refrigerant gas such as R 22.

A. Boil-off
B. Cascade Reliquefaction Cycle
C. BLEVE
D. Boiling Point

Answer: B — Cascade Reliquefaction Cycle

In the cascade reliquefaction cycle, cargo boil-off vapour is compressed and condensed in a cargo condenser cooled by a refrigerant gas such as R22, which is itself cooled by a separate refrigeration cycle. The liquid cargo is then returned to the tanks.

3. _____________ is the process occurring within the impeller of a pump when pressure at the inlet to the impeller falls below the vapour pressure of the liquid being pumped.

A. Cascade Reliquefaction Cycle
B. Boil-off
C. Cavitation
D. BLEVE

Answer: C — Cavitation

Cavitation happens when impeller inlet pressure falls below the liquid's vapour pressure, so vapour bubbles form.

4. In Cavitation process, the bubbles of vapour that are formed collapse with impulsive force in the _________ pressure regions of the impeller.

A. medium
B. lower
C. higher
D. zero

Answer: C — higher

Vapour bubbles formed at low pressure collapse violently when carried into the higher-pressure regions of the impeller, which erodes it.

5. Cavitation effect can cause significant damage to the

A. pumps may lose suction
B. impeller surfaces
C. both (a) and (b)
D. none of the above

Answer: C — both (a) and (b)

Cavitation is the formation and violent collapse of vapour bubbles at low-pressure points in a pump. The collapse pits and erodes the impeller surfaces, and the vapour also makes the pump lose suction and capacity.

6. What are checked during the certificate of Fittness?

A. structure
B. All of the above
C. equipment
D. fittings

Answer: B — All of the above

Before a Certificate of Fitness is issued under the IGC or IBC Code, the ship's structure, equipment and fittings are all surveyed to confirm they meet the Code. All of these items are checked.

7. ___________ ia the isolating space on a ship between two adjacent steel bulkheads or deck

A. Cofferdam
B. Cargo conatinment system
C. Compressor pumps
D. Cavitation

Answer: A — Cofferdam

IGC Code 1.2: a cofferdam is the isolating space between two adjacent steel bulkheads or decks.

8. Cofferdam is the isolating space on a ship between __________

A. both (a) and (b)
B. none of the above
C. deck
D. two adjacent steel bulkheads

Answer: A — both (a) and (b)

A cofferdam is an empty space between two adjacent steel bulkheads or decks, used to separate cargo tanks from other spaces. It acts as a barrier against leaks, gas and heat, as required by the IGC and IBC Codes.

9. ___________ is the reliquefied gases which collect in the condenser and which are then returned to the cargo tanks.

A. BLEVE
B. Cofferdam
C. Condensate
D. Aerating

Answer: C — Condensate

Condensate is the liquid formed when boil-off vapour is compressed and cooled in the reliquefaction plant condenser. It collects in the condenser or receiver and is returned to the cargo tanks, reducing cargo loss and controlling tank pressure.

10. Compression Ratio is the ratio of the absolute _____________ the discharge from a compressor divided by the absolute pressure at the suction

A. mass
B. temperature
C. pressure
D. volume

Answer: C — pressure

Compression ratio compares absolute pressures: absolute discharge pressure divided by absolute suction pressure. It indicates the work done by each compressor stage in gas carrier reliquefaction plants and is limited to control discharge temperature.

11. _____________ is the ratio of the absolute pressure at the discharge from a compressor divided by the absolute pressure at the suction

A. Temperature Ratio
B. Compression Ratio
C. Compressing ratio
D. Freezing ratio

Answer: B — Compression Ratio

The ratio of absolute discharge pressure to absolute suction pressure of a compressor is called the compression ratio. High ratios raise discharge temperature, so reliquefaction plants use multi-stage compression with intercooling to keep it within limits.

12. Natural gas contains ________ quantities of heavier hydrocarbons

A. zero
B. medium
C. bigger
D. smaller

Answer: D — smaller

Natural gas is mainly methane, with smaller quantities of heavier hydrocarbons such as ethane, propane and butane plus some nitrogen. These heavier fractions affect the boiling point, density and methane number of LNG used as fuel under the IGF Code.

13. Natural gas contains smaller quantities of ______hydrocarbons

A. medium
B. heavier
C. lighter
D. partial

Answer: B — heavier

Natural gas consists predominantly of methane and contains only smaller quantities of heavier hydrocarbons such as ethane, propane and butane. The proportion of these heavier components varies with the gas field and influences LNG composition and quality.

14. Natural gas contains smaller quantities of heavier ________

A. hydrocarbons
B. carbons
C. nitrogen
D. oxygen

Answer: A — hydrocarbons

Natural gas is mainly methane, with smaller quantities of heavier hydrocarbons (ethane, propane, butane) plus some N2/CO2.

15. Natural gas contains smaller quantities of heavier hydrocarbons collectively called as _________

A. Neutral Gas Liquid
B. Natural Gas Limit
C. Natural Gas Liquid
D. Nitrogen Gas Liquid

Answer: C — Natural Gas Liquid

Natural Gas Liquids (NGL) refer to the heavier hydrocarbon components (ethane, propane, butane, pentane plus) separated from raw natural gas streams.

16. What are the things Natural gas contains in varying amounts?

A. carbondioxide
B. hydrocarbon
C. All of the above
D. water

Answer: C — All of the above

Raw natural gas contains methane, ethane, propane, butane, inert gases (nitrogen, helium), and acid contaminants (CO2, H2S, mercaptans).

17. What are the acid gases removed in liquefaction plant?

A. carbon dioxide
B. none of the above
C. both (a) and (b)
D. hydrogen sulphide

Answer: C — both (a) and (b)

Acid gases like carbon dioxide (CO2) and hydrogen sulfide (H2S) must be scrubbed from natural gas before liquefaction to prevent corrosion and freezing.

18. In liquefaction plant which gas is removed as it freezes at a temperature above boiling point of Liquified Natural Gas

A. methane
B. ethane
C. carbon dioxide
D. hydrocarbons

Answer: C — carbon dioxide

Carbon dioxide freezes at -78.5°C, well above the liquefaction temperature of LNG (-162°C), and must be removed to prevent solid plugging in heat exchangers.

19. In liquefaction plant which toxic compound is removed?

A. All of the above
B. nitrogen sulphide
C. hydrogen sulphide
D. carbondioxide

Answer: C — hydrogen sulphide

Hydrogen sulfide (H2S) is a highly toxic, corrosive gas removed during gas sweetening processes to meet safety and transport specifications.

20. In liquefaction plant, fractionating unit name the gas which is split?

A. Butane
B. none of the above
C. Propane
D. both (a) and (b)

Answer: D — both (a) and (b)

In a gas liquefaction plant the fractionating unit separates the heavier natural gas liquids from the methane stream. The LPG fraction is split into its components, propane and butane, so both gases are produced by fractionation.

21. In liquefaction plant, which gas is liquefied into end product?

A. Oxygen
B. none of the above
C. hydrogen
D. Methane

Answer: D — Methane

In an LNG liquefaction plant, the purified, chilled methane stream is liquefied and sent to cryogenic storage tanks as the final LNG product.

22. What is the atmospheric boiling point of methane gas?

A. atmospheric boiling point is +172deg C
B. atmospheric boiling point is - 162deg C
C. atmospheric boiling point is +192deg C
D. atmospheric boiling point is +162deg C

Answer: B — atmospheric boiling point is - 162deg C

The boiling point of methane at normal atmospheric pressure (1.013 bar) is approximately -161.5°C (standard rounded to -162°C).

23. The basic liquefaction processes in current use are

A. Pre-cooled mixed refrigerant process
B. Pure refrigerant cascade process
C. All of the above
D. Mixed refrigerant process

Answer: C — All of the above

Major commercial LNG liquefaction cycles include the C3MR (propane pre-cooled mixed refrigerant) process, cascade cycles, and nitrogen expansion loops.

24. In Pre-cooled mixed refrigerant process, what is MCR

A. Multi Component Refrigerant
B. Multi Cascade Refinement
C. Minimum Combination Refrigerant
D. Multi Cascade Refrigerant

Answer: A — Multi Component Refrigerant

MCR stands for Multi-Component Refrigerant (or Mixed Refrigerant), utilizing a optimized blend of nitrogen, methane, ethane, and propane.

25. In Pre-cooled mixed refrigerant process, Multi Component Refrigerant is a combination of

A. both (a) and (b)
B. none of the above
C. mixed refrigerant cycles
D. pure refrigerant cascadecycles

Answer: A — both (a) and (b)

The mixed refrigerant stream in LNG liquefaction plants consists of tailored mixtures of nitrogen, methane, ethane/ethylene, propane, and butane.

26. Liquefied Petroleum Gas is obtained from the refining of __________

A. All of the above
B. crude oil
C. Vegetable oil
D. fatty oil

Answer: B — crude oil

Commercial LPG is produced both by extracting NGLs from natural gas processing and through fractional distillation and catalytic cracking of crude oil.

27. In production of chemical gases, from Propane which gas is produced indirectly

A. ammonia
B. All of the above
C. vinyl chloride
D. ethylene

Answer: B — All of the above

Propane dehydrogenation and petrochemical cracking processes produce chemical intermediates such as propylene, ethylene, and downstream derivatives.

28. In production of chemical gases, The ethylene stream can be synthesized with chlorine to manufacture __________

A. vinyl chloride
B. ethylene
C. All of the above
D. ammonia

Answer: A — vinyl chloride

Ethylene is chlorinated to form ethylene dichloride (EDC), which is then thermally cracked to produce Vinyl Chloride Monomer (VCM) for PVC production.

29. In production of chemical gases, The methane stream is first reformed with steam into _________

A. nitrogen
B. hydrogen
C. vinyl chloride
D. carbondioxide

Answer: B — hydrogen

In chemical synthesis, methane is reacted with high-temperature steam over a nickel catalyst in steam methane reforming (SMR) to produce hydrogen and carbon monoxide.

30. In production of chemical gases, By combining with nitrogen under high pressure and temperature in the presence of a catalyst __________ is produced.

A. hydrogen
B. carbondioxide
C. ammonia
D. vinyl chloride

Answer: C — ammonia

Ammonia is synthesized industrially via the Haber-Bosch process by reacting reformed hydrogen with atmospheric nitrogen under high pressure and temperature over an iron catalyst.

Set 4 — 30 BIGF exit exam questions with answers

1. In IGF Code, L is the _______ as defined in the International Convention on Load Lines in force.

A. less
B. length
C. least
D. lower

Answer: B — length

Under the IGF Code, vessel Length (L) is defined in accordance with the International Convention on Load Lines in force.

2. In IGF Code, Length (L) is the length as defined in the ___________ in force

A. International Convention on Level Lines
B. Indian Convention on Load Lines
C. International Convention on Load Lines
D. Independent Convention on Load Lines

Answer: C — International Convention on Load Lines

The standard definition of ship length (L) in the IGF Code references the criteria specified under the International Convention on Load Lines.

3. In IGF Code, MARVS means

A. Minimum allowable relief value setting
B. Maximum allowable relief value setting
C. Minimum allowable relief valve setting
D. Maximum allowable relief valve setting

Answer: D — Maximum allowable relief valve setting

MARVS stands for Maximum Allowable Relief Valve Setting, the design pressure limit set on cargo/fuel tank pressure relief valves.

4. In IGF Code, MAWP means

A. Minimum allocated working pressure
B. Maximum allowable working pressure
C. Minimum allowable working pressure
D. Maximum allocated working pressure

Answer: B — Maximum allowable working pressure

MAWP stands for Maximum Allowable Working Pressure, the maximum gauge pressure permissible at the top of a tank or piping system in operational service.

5. In IGF Code, Membrane tanks means

A. an tank in which an explosive gas atmosphere a flammable gas or vapour is or may be expected to be present
B. an tank in which an explosive gas atmosphere or a flammable gas or vapour is present continuously or is present for long periods
C. self-supporting, do not form part of the ship's hull and are not essential to the hull strength
D. non-self-supporting tanks that consist of a thin liquid and gas tight layer membrane) supported through insulation by the djacent hull structure

Answer: D — non-self-supporting tanks that consist of a thin liquid and gas tight layer membrane) supported through insulation by the djacent hull structure

Membrane tanks are non-self-supporting fuel containment systems composed of a thin liquid and gas-tight metallic barrier supported through load-bearing insulation by the adjacent inner hull.

6. What is critical pressure?

A. The pressure at which a substance exists in the solid state at its critical temperature.
B. The pressure at which a substance exists in the liquid state at its critical temperature.
C. ATMOSPHERIC PRESSURE
D. none of the above

Answer: B — The pressure at which a substance exists in the liquid state at its critical temperature.

Critical pressure is the minimum pressure required to liquefy a gas at its critical temperature.

7. The pressure at which a substance exists in the _______ state at its critical temperature is called critical pressure.

A. semi solid
B. liquid
C. solid
D. vapour

Answer: B — liquid

Critical pressure represents the saturation pressure corresponding to the substance's critical point temperature where liquid and vapor phases become indistinguishable.

8. Explanation for critical pressure?

A. The pressure at which a substance exists in the liquid state at its critical temperature is called critical pressure.
B. both (a) and (b)
C. Critical pressure is the saturation pressure at the critical temperature.
D. none of the above

Answer: B — both (a) and (b)

At the critical point, the liquid and vapor densities become equal and no distinct phase boundary exists, regardless of additional pressure application.

9. Critical temperature is ________________

A. The temperature above which a semi solid cannot be liquefied by pressure alone.
B. The temperature above which a gas cannot be liquefied by pressure alone.
C. none of the above
D. The temperature above which a solid cannot be liquefied by pressure alone.

Answer: B — The temperature above which a gas cannot be liquefied by pressure alone.

Critical temperature is the maximum temperature above which a gas cannot be liquefied, no matter how much external pressure is applied.

10. ________________ is the temperature above which a gas cannot be liquefied by pressure alone.

A. Absolute temperature
B. Critical temperature
C. Critical pressure
D. Absolute pressure

Answer: B — Critical temperature

Above the critical temperature, a substance exists solely as a supercritical fluid and cannot be condensed into a distinct liquid phase by pressure alone.

11. ______________ is the endorsement issued by a flag state administration to a certificate of competency of a ship's officer allowing service on dangerous cargo carriers such as oil tankers, chemical tankers or gas carriers.

A. Bulk cargo
B. EXEMPTION
C. Dangerous Cargo Endorsement
D. Cargo containment system

Answer: C — Dangerous Cargo Endorsement

A Dangerous Cargo Endorsement (DCE) is a statutory endorsement issued by the maritime administration to an officer's Certificate of Competency for service on tankers or gas carriers.

12. Dangerous Cargo Endorsement is the endorsement issued by a flag state administration to a certificate of competency of a ship's office rallowing service on dangerous cargo carriers such as ______________

A. chemical tankers
B. gas carriers
C. All of the above
D. oil tankers

Answer: C — All of the above

Dangerous Cargo Endorsements are required under STCW regulations for certified officers serving on oil tankers, chemical tankers, and liquefied gas carriers.

13. Dangerous Cargo Endorsement is the endorsement issued by a flag state administration to a ______________ ship's officer allowing service on dangerous cargo carriers such as oil tankers, chemical tankers or gas carriers.

A. continuous discharge certificate
B. Indos
C. certificate of competency
D. none of the above

Answer: C — certificate of competency

A Dangerous Cargo Endorsement is formally attached to the officer's Certificate of Competency (CoC) upon satisfying mandatory STCW sea time and specialized training.

14. Density is the mass per unit volume of a substance at specified conditions of_________

A. temperature
B. none of the above
C. both (a) and (b)
D. pressure

Answer: C — both (a) and (b)

Density is the physical mass of a substance per unit volume (kg/m³), which varies as a function of temperature and pressure.

15. ________ is the mass per unit volume of a substance at specified conditions of temperaure and pressure.

A. Volume
B. Dew point
C. Density
D. Pressure point

Answer: C — Density

Density expresses the ratio of mass to volume of a fuel gas or liquid at standard reference temperature and pressure conditions.

16. ___________ is the temperature at which condensation will take place within a gas if further cooling occurs.

A. Flame
B. Enthalpy
C. Bleve
D. Dew point

Answer: D — Dew point

Dew point is the saturation temperature at which water vapor or hydrocarbon gas begins to condense into liquid droplets upon cooling at constant pressure.

17. Enthalpy is a ___________ measure of the total heat content of a lliquid at a given temperature.

A. equlibria
B. irreversible
C. reversible
D. thermodynamic

Answer: D — thermodynamic

Enthalpy is a fundamental thermodynamic state property representing the total heat energy content (internal energy plus pressure-volume work) of a substance.

18. Enthalpy is expressed in ____________

A. k joules per unit
B. k joules per 1 kg
C. k joules per M
D. k joules per volume

Answer: B — k joules per 1 kg

Specific enthalpy in maritime thermodynamics is standardly expressed in units of kilojoules per kilogram (kJ/kg).

19. In Enthalpy, for a liquid / vapour mixture, it will be seen that it is the sum of ________________

A. the latent heat of vaporization
B. the enthalpy of the liquid
C. none of the above
D. both (a) and (b)

Answer: D — both (a) and (b)

For a saturated liquid-vapor mixture, total enthalpy is the sum of liquid sensible enthalpy and the latent heat of vaporization multiplied by vapor quality.

20. Synonyms of methane is

A. marsh gas
B. LNG
C. natural gas
D. All of the above

Answer: D — All of the above

Methane (CH4) is also commonly known as marsh gas, firedamp, methyl hydride, or natural gas.

21. Synonyms of ethane is

A. methyl methane
B. dimethyl
C. bimethyl
D. All of the above

Answer: D — All of the above

Ethane (C2H6) is also referred to as bimethyl, dimethyl, or ethyl hydride.

22. Synonyms of n-butane is

A. iso butane
B. methlypropane
C. All of the above
D. normal butane

Answer: D — normal butane

n-Butane refers to normal butane (unbranched straight-chain C4H10 hydrocarbon).

23. Synonyms of i-butane is

A. methlypropane
B. none of the above
C. iso butane
D. both (a) and (b)

Answer: D — both (a) and (b)

Isobutane (i-butane) is 2-methylpropane, a branched constitutional isomer of butane.

24. Synonyms of α butylene is

A. none of the above
B. But-1-ene
C. both (a) and (b)
D. ethyl ethylene

Answer: C — both (a) and (b)

Alpha-butylene refers to 1-butene (C4H8), an unsaturated terminal alkene monomer.

25. To ensure no release occurs during the hook-up or disconnection of components during bunkering, which of the following is necessary?

A. Draining of the bunker piping system only
B. Gassing up of the bunker piping system with LNG before connection or disconnection
C. Purging of the bunker piping system with inert gas before connection or disconnection
D. None of the above

Answer: C — Purging of the bunker piping system with inert gas before connection or disconnection

The IGF Code requires the bunkering lines to be drained and purged with inert gas (normally nitrogen) before connecting or disconnecting, so that no flammable gas is released at the manifold.

26. What is provided in bilge well in each tank connection space of an independent iqueted yes surge and

A. a level indicator
B. a temperature sensor
C. unsafety systems
D. both (a) and (b)

Answer: D — both (a) and (b)

IGF Code 6.? (tank connection spaces): the bilge well in each tank connection space of an independent liquefied gas tank shall have both a level indicator and a temperature sensor. The stem is garbled.

27. Substance of cargo vapour in air which is not flammable

A. Ammonia
B. Methane
C. Chlonine
D. Propane

Answer: C — Chlonine

Chlorine is non-flammable (it is an oxidiser). Ammonia, methane and propane all have flammable ranges in air.

28. For engines fitted with ignition systems, when would the, correct operaton of the goon system on each unit shal be verified?

A. prior to admission of gas fuel
B. after admission of gas fuel
C. every three months
D. as time permits

Answer: A — prior to admission of gas fuel

On dual-fuel engines with pilot ignition, the correct operation and timing of the pilot fuel ignition system must be automatically verified on each cylinder prior to admitting gas fuel.

29. Stop valves shall be fitted in the water spray application main supply line:

A. At intervals not exceeding 35 metres, for the purpose of isolating damaged sections
B. At intervals not exceeding 45 metres, for the purpose of isolating damaged sections
C. At intervals not exceeding 50 metres, for the purpose of isolating damaged sections
D. At intervals not exceeding 40 metres, for the purpose of isolating damaged sections

Answer: D — At intervals not exceeding 40 metres, for the purpose of isolating damaged sections

Stop valves must be installed in the water spray main supply line at intervals not exceeding 40 meters to enable isolation of damaged pipe sections during a fire.

30. You should always check closed doors for before opening them

A. heat from fire.
B. paint
C. cleanliness
D. None of the above

Answer: A — heat from fire.

Before opening closed doors during a fire emergency, always check the door and handle for heat with the back of a gloved hand to avoid sudden backdrafts or exposing yourself to intense flames.

Set 5 — 30 BIGF exit exam questions with answers

1. How is the gas detection required?

A. non-continuous with delay
B. continuous without delay
C. continuous with delay
D. non-continuoss without delay

Answer: B — continuous without delay

IGF Code 15.8: gas detection shall be continuous, without delay.

2. Air locks provides __ _

A. free and easy passage
B. a deck area not less than 1.5 m²
C. both (a) and (b)
D. none of the above

Answer: C — both (a) and (b)

Under the IGF Code an air lock is a space enclosed by gas-tight bulkheads with two gas-tight doors. It must give free and easy passage and have a deck area of not less than 1.5 m², so both statements are correct.

3. Ventilation systems is required to avoid __ _

A. gas accumulation
B. gas seperation
C. gas maintenance
D. none of the above

Answer: A — gas accumulation

Mechanical ventilation systems in gas fuel machinery spaces and double-wall piping are designed to run continuously to prevent any accumulation of flammable gas pockets.

4. What is the ventilation capacity of fuel preparaton rooms, pump and compressor rooms?

A. 30 air changes per hour
B. 30 air changes per sec
C. 30 air changes per min
D. 30 air changes per milli sec

Answer: A — 30 air changes per hour

The IGF Code mandates that fuel preparation rooms, compressor rooms, and pump rooms must be equipped with an independent mechanical extraction ventilation system providing at least 30 air changes per hour.

5. Fuel containment system and machinery spaces containing source that might release gas into the space shall be arranged and located such that

A. In case of fuel gas leakage it will not affect personnel
B. A fire or explosion in either will not lead to an unacceptable loss of power
C. Leakage will not affect accomodation area
D. There is no complete blackout

Answer: B — A fire or explosion in either will not lead to an unacceptable loss of power

IGF Code 5.3 / functional requirements: fuel containment and machinery spaces shall be arranged so that a fire or explosion in either will not lead to an unacceptable loss of power or make equipment in other compartments inoperable.

6. Substance of cargo vapour in air which is not toxic

A. Propane
B. Ethylene
C. Methane
D. All the above

Answer: D — All the above

Propane, ethylene and methane are non-toxic simple asphyxiants (no TLV toxicity hazard in gas data sheets), so all of the above.

7. What is the use of tankscope?

A. An instrument used for measuring hydrocarbon vapour in inerted atmospheres
B. An instrument used for measuring carbon vapour in inerted atmospheres
C. An instrument used for measuring oxygen vapour in inerted atmospheres.
D. An instrument used for measuring dioxide vapour in inerted atmospheres

Answer: A — An instrument used for measuring hydrocarbon vapour in inerted atmospheres

A Tankscope is a specialized non-catalytic optical/thermal conductivity instrument specifically designed to measure hydrocarbon gas concentrations (0-100% volume) in inert nitrogen or flue-gas atmospheres where catalytic bead explosimeters cannot operate.

8. Risk assesment needs to be carried out and applied for

A. Sizing of drip trays
B. Design of airlocks
C. Liquefied gas containment system;
D. All af above

Answer: C — Liquefied gas containment system;

A formal risk assessment must be carried out for the design, material selection, and structural arrangement of the liquefied gas fuel containment system to evaluate all failure modes.

9. 1 sS Exam 25. During bunkering, an area of sufficient size that keeps other vessels, vehicles, equipment, and cargo operations far enough away so that they pose little risk of damaging or interfering with the LNG bunkering system and equipment is called:

A. Safety Zone
B. Security Zone
C. Hazardous Area
D. ISPS Border

Answer: A — Safety Zone

The bunkering safety zone is a designated perimeter around the bunkering manifold and fuel storage areas where unauthorized activities, hot work, and non-certified equipment are strictly prohibited.

10. In Overflow control, What will an additional sensor operating independently of the high liquid level alarm do?

A. automatically actuate a switchon valve
B. automatically actuate a shutoff valve
C. manually actuate a shutoff valve
D. manually actuate a switchon valve

Answer: B — automatically actuate a shutoff valve

In fuel tank overflow control systems, an independent high-high level sensor (operating independently of the 95% level alarm) automatically actuates the emergency shutoff valve to prevent overfilling.

11. As per the regulation, It shall be possible to empty, purge and vent fuel storage tanks with fuel piping systems. Prior to venting with dry air to avoid an explosion hazardous atmosphere in tanks and fuel pipes what should be performed?

A. Inerting shall be performed.
B. Gassing up shall be performed.
C. Cooling down should be performed.
D. none of the above

Answer: A — Inerting shall be performed.

Prior to aerating fuel tanks or fuel piping with dry air, thorough inerting with dry nitrogen must be performed to ensure the hydrocarbon concentration is reduced below the flammable range.

12. Accident Limit States (ALS) relevant design parameters of limit state design of fuel containment systems

A. correspond to the maximum load-carrying capacıty
B. correspond to degradation due to the effect of cyclic loading
C. concern the ability of the structure to resist accident situations
D. none of the above

Answer: C — concern the ability of the structure to resist accident situations

Accidental Limit States (ALS) criteria in fuel containment design assess structural resistance against abnormal collision, grounding, fire exposure, or cryogenic blast loading.

13. The bunkering system shall be so arranged that

A. No leakage takes place
B. No gas is discharged to the atmosphere during filling of storage tanks
C. The bunkering system withstands fluctuation in loading pressures
D. The bunkering system withstands fluctuation in ambient temperatures

Answer: B — No gas is discharged to the atmosphere during filling of storage tanks

The bunkering system must be designed so that no gas vapor is vented or discharged to the atmosphere during fuel storage tank filling operations, utilizing vapor return lines where necessary.

14. Electric equipment installed in explosion hazardous spaces and areas

A. Should have routine maintenance schedule as per PMS
B. Must be inspected and surveyed as per requiremnt of Adminstration
C. Should have the procedures and information regarding in-service survey, maintenance and resting
D. Should be intristically safe

Answer: B — Must be inspected and surveyed as per requiremnt of Adminstration

All electrical equipment installed in explosion-hazardous spaces must be certified safe (Ex-rated), documented in the hazardous area register, and regularly surveyed in accordance with Administration rules.

15. LNG in liquid state is :

A. highly flammable and easily ignite
B. not flammable and cannot ignite
C. not toxic and can ignite
D. none of the above

Answer: C — not toxic and can ignite

In its pure liquid state, LNG is non-toxic, clear, and non-corrosive, but it vaporizes rapidly into flammable methane gas that ignites readily when mixed with air within its flammability limits.

16. What will be the Emergency Shutdown protected machinery space fallure?

A. the spaces are considered gas safe under all conditions
B. a single failure cannot lead to release of fuel gas into the machinery space
C. a single failure may result in a gas release into the space
D. none of the above

Answer: C — a single failure may result in a gas release into the space

IGF Code 2.2 / 5.6: in an ESD-protected machinery space, a single failure may result in gas release into the space, and ESD isolates and shuts down. In a gas-safe space it cannot.

17. For fuel tanks fitted with PRVs, which can be set at more than one set pressure, What is provided for each set pressure?

A. safe-pressure alarms
B. medium-pressure alarms
C. high-pressure alarms
D. low-pressure alarms

Answer: C — high-pressure alarms

IGF Code 15.6: where PRVs can be set at more than one set pressure, high-pressure alarms shall be provided for each set pressure.

18. For each main gas supply line entering an ESD protected machinery space, and each gas supply line to high pressure installations

A. Means shall be provided for rapid detection of a rupture in the gas line in the engine-room.
B. The pipelines should be always double walled
C. In case of gas leakage an automatic alarm should actuate
D. Due to redundancy there should not be any unacceptable loss of power

Answer: A — Means shall be provided for rapid detection of a rupture in the gas line in the engine-room.

For main gas supply lines entering ESD-protected machinery spaces, automated monitoring must provide rapid detection of any pressure drop or line rupture to trigger instantaneous fuel trip valves.

19. What is the critical temperature (deg C) of vinyl chloride?

A. -6592.0
B. 158.4
C. -6214.0
D. -6524.0

Answer: B — 158.4

The critical temperature of Vinyl Chloride Monomer (VCM) is 158.4°C, above which it cannot exist as a separate liquid phase.

20. What is the critical temperature (deg C) of ethylene oxide?

A. 195.7
B. -6249.0
C. -5486.0
D. -5947.0

Answer: A — 195.7

The critical temperature of Ethylene Oxide is 195.7°C, with a critical pressure of approximately 71.9 bar.

21. What is the critical temperature (deg C) of propylene oxide?

A. -6593.0
B. 209.1
C. -8529.0
D. -6219.0

Answer: B — 209.1

The critical temperature of Propylene Oxide is 209.1°C, with a critical pressure of approximately 49.2 bar.

22. What is the critical temperature (deg C) of ammonia?

A. -5627.0
B. 132.4
C. -5649.0
D. -6597.0

Answer: B — 132.4

The critical temperature of Anhydrous Ammonia (NH3) is 132.4°C, with a critical pressure of 112.8 bar.

23. What is the critical temperature (deg C) of Chlorine?

A. -9657.0
B. -2546.0
C. -5698.0
D. 144.0

Answer: D — 144.0

The critical temperature of Chlorine (Cl2) is 144.0°C, with a critical pressure of 77.1 bar.

24. What is the critical pressure (bars, absolute) of Methane?

A. 44.7
B. -2345.0
C. -6249.0
D. -5947.0

Answer: A — 44.7

The critical pressure of Methane (CH4) is 45.99 bar absolute (commonly referenced in maritime gas tables as 44.7 to 46.0 bar absolute).

25. What is the critical pressure (bars, absolute) of Ethane?

A. -7648.0
B. -5486.0
C. -8529.0
D. 48.9

Answer: D — 48.9

The critical pressure of Ethane (C2H6) is 48.8 bar absolute (approx. 48.9 bar absolute).

26. Which gas is considered as Fuel [in the context of this code] in liquid and compressed form

A. All the above
B. propane
C. Natural gas
D. i-Butane

Answer: A — All the above

Under the IGF Code, gases considered as fuel in liquid or compressed forms include natural gas (methane), LPG (propane/butane), ethane, and synthetic gas fuels.

27. In IGF Code, Which is called Fuel containment system

A. Any tank
B. Cargo tank
C. the transfer of liquid from land based
D. the arrangement for the storage of fuel including and connections

Answer: D — the arrangement for the storage of fuel including and connections

Under the IGF Code, the Fuel Containment System is the complete arrangement for storing fuel, including tank primary barriers, secondary barriers, insulation, and tank connection spaces.

28. In IGF Code, Independent tanks means

A. none of the above
B. both (a) and (b)
C. are not essential to the hull strength
D. self-supporting, do not form part of the ship's hull

Answer: B — both (a) and (b)

Independent tanks are self-supporting fuel containment structures that do not form part of the ship's hull and do not contribute to overall hull girder strength.

29. ____________is capable of being ignited.

A. Inflammable
B. Flammable
C. Absolute temperature
D. Absolute zero

Answer: B — Flammable

A substance is classified as flammable if it is capable of being ignited and burning in the presence of an oxidizer.

30. _________ is the range of gas concentrations in air between which the mixture is flammable.

A. Inflammable range
B. Flammable range
C. Pressure range
D. Temperature range

Answer: B — Flammable range

The flammable range (or explosive range) is the range of fuel gas concentrations in air (between LEL and UEL) within which combustion can occur upon ignition.

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.

Set 7 — 30 BIGF exit exam questions with answers

1. How is gas replacement achieved in a tank by the displacement method?

A. A lighter incoming gas is introduced beneath a heavier existing gas at low velocity
B. A lighter incoming gas is introduced beneath a heavier existing gas at high velocity
C. A heavier incoming gas is introduced beneath a lighter existing gas at low velocity
D. A heavier incoming gas is introduced on top of a lighter existing gas at high velocity

Answer: C — A heavier incoming gas is introduced beneath a lighter existing gas at low velocity

In displacement, the gases must stay layered. A heavier gas is fed slowly into the bottom of the tank and the lighter gas is pushed out through the top. Low velocity keeps a stable interface with minimal mixing.

2. With regard to MARPOL, identify the INCORRECT statement.

A. MARPOL specifies standards for stowing, handling, shipping and transferring pollutant cargoes
B. MARPOL specifies standards for the discharge of ship-generated wastes
C. MARPOL 73/78 consists of seven annexes, each covering a different source of ship-generated pollution
D. Acceptance of the convention by a national government obliges it to make the requirements part of domestic law

Answer: C — MARPOL 73/78 consists of seven annexes, each covering a different source of ship-generated pollution

MARPOL has six annexes: oil, noxious liquid substances in bulk, harmful substances in packaged form, sewage, garbage, and air pollution and energy efficiency. A statement claiming seven annexes is therefore incorrect.

3. In relation to ship's boiler thermodynamics, identify the INCORRECT statement.

A. Enthalpy is the sum of a fluid's internal energy and the flow work required to move it through the system
B. In steady-flow processes, the work of pushing fluid through the system may not change to any great extent
C. Any change in enthalpy equals the quantity of heat gained or lost in a constant-pressure process
D. Enthalpy is always expressed as a total that must be measured from absolute zero

Answer: D — Enthalpy is always expressed as a total that must be measured from absolute zero

Only changes in enthalpy matter in practice, so it is measured from an agreed datum, not from absolute zero. Steam tables take saturated water at 0.01°C as zero, so an absolute total from absolute zero is not required.

4. As per the IGF Code, high-pressure fuel piping is piping with a maximum working pressure of ____.

A. More than 6 bar
B. More than 10 bar
C. More than 16 bar
D. More than 300 bar

Answer: B — More than 10 bar

The IGF Code defines high-pressure piping as gas or low-flashpoint fuel piping with a maximum working pressure above 1.0 MPa (10 bar). Such piping must meet stricter requirements, such as double-walled pipes or ducts and extra testing.

5. A ____ is required for immediate inerting, because nitrogen deliveries are in liquid form.

A. Nitrogen vaporiser
B. Hydrogen vaporiser
C. Oxygen vaporiser
D. None of these

Answer: A — Nitrogen vaporiser

Nitrogen delivered as liquid must be vaporised before it can be used to inert tanks and pipes. A liquid nitrogen vaporiser provides large volumes of dry, oxygen-free inert gas quickly, for example for purging before maintenance or after bunkering.

6. Through which SOLAS chapter and part was the IGF Code made mandatory?

A. Chapter VI, Part B
B. Chapter II-2, Part C
C. Chapter II-1, Part G
D. Chapter VII, Part C

Answer: C — Chapter II-1, Part G

The IGF Code was made mandatory by amendments to SOLAS Chapter II-1, which added Part G (Regulations 56 and 57) for ships using low-flashpoint fuels, in force from 1 January 2017.

7. On what date did the IGF Code enter into force?

A. 1 July 2015
B. 1 January 2020
C. 1 July 2012
D. 1 January 2017

Answer: D — 1 January 2017

The International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code), adopted by resolution MSC.391(95), entered into force on 1 January 2017 together with the related SOLAS and STCW amendments.

8. The IGF Code applies to ships, other than those covered by the IGC Code, that use fuels with a flashpoint lower than:

A. 43°C
B. 60°C
C. 100°C
D. 35°C

Answer: B — 60°C

SOLAS II-2/4.2.1.1 generally prohibits fuel oils with a flashpoint below 60°C; ships using gases or other low-flashpoint fuels below this limit must comply with the IGF Code under SOLAS II-1 Part G.

9. Which STCW regulation contains the mandatory minimum requirements for training of seafarers on ships subject to the IGF Code?

A. Regulation V/2
B. Regulation VI/1
C. Regulation V/3
D. Regulation V/1-2

Answer: C — Regulation V/3

STCW Regulation V/3, with Section A-V/3 and Tables A-V/3-1 and A-V/3-2, sets out basic and advanced training for masters, officers, ratings and other personnel on ships subject to the IGF Code.

10. Basic training for ships subject to the IGF Code is required for seafarers responsible for:

A. Catering and hotel services only
B. Designated safety duties associated with the care, use or emergency response to the fuel
C. Navigational watchkeeping only
D. Cargo handling on oil tankers

Answer: B — Designated safety duties associated with the care, use or emergency response to the fuel

Under STCW Regulation V/3, seafarers responsible for designated safety duties associated with the care, use or emergency response to the fuel on IGF ships must hold a certificate in basic training per Table A-V/3-1.

11. Which personnel on a ship subject to the IGF Code require advanced training in accordance with STCW Table A-V/3-2?

A. Only the master
B. Only shore bunkering staff
C. Masters, engineer officers and all personnel with immediate responsibility for the care and use of fuels and fuel systems
D. All ratings forming part of a navigational watch

Answer: C — Masters, engineer officers and all personnel with immediate responsibility for the care and use of fuels and fuel systems

STCW Regulation V/3 requires masters, engineer officers and all personnel with immediate responsibility for the care and use of fuels and fuel systems on IGF ships to complete advanced training per Table A-V/3-2.

12. Which functional requirement of the IGF Code applies to the safety of fuel systems?

A. Any failure may be accepted if an alarm is given
B. Fuel systems need no redundancy if the ship is under 500 GT
C. Gas fuel shall be used only in port
D. A single failure in a technical system or component shall not lead to an unsafe or unreliable situation

Answer: D — A single failure in a technical system or component shall not lead to an unsafe or unreliable situation

Among the IGF Code functional requirements in Part A, a single failure in a technical system or component shall not lead to an unsafe or unreliable situation, which drives redundancy and segregation in fuel arrangements.

13. A ship whose engines can run either on gas fuel or on conventional oil fuel is described as a:

A. Steam turbine installation
B. Dual-fuel installation
C. Gas-only installation
D. Single-fuel installation

Answer: B — Dual-fuel installation

A dual-fuel installation can operate on gas fuel or on liquid fuel oil; a single gas-fuel installation runs only on gas, so the IGF Code requires additional redundancy of fuel supply for such ships.

14. Which IMO instrument provides the safety provisions for ships using methyl or ethyl alcohol as fuel?

A. MARPOL Annex II
B. The IBC Code Chapter 17
C. MSC.1/Circ.1621 Interim Guidelines
D. The FSS Code Chapter 9

Answer: C — MSC.1/Circ.1621 Interim Guidelines

Part A-1 of the IGF Code covers natural gas only; ships using methyl/ethyl alcohol as fuel apply the Interim Guidelines in MSC.1/Circ.1621, which supplement the general IGF Code requirements.

15. The IGF Code contains detailed prescriptive requirements (Part A-1) specifically for which fuel?

A. Hydrogen
B. Methanol
C. Ammonia
D. Natural gas

Answer: D — Natural gas

Part A-1 of the IGF Code contains specific requirements for ships using natural gas as fuel; other low-flashpoint fuels must meet the functional requirements via alternative design or IMO interim guidelines.

16. Which type of independent tank is designed as a pressure vessel and does not require a secondary barrier?

A. Membrane tank
B. Type C
C. Type A
D. Type B

Answer: B — Type C

Type C independent tanks are pressure vessels built to pressure-vessel criteria, so the IGF Code does not require a secondary barrier for them; Type A and membrane tanks need a complete secondary barrier and Type B a partial one.

17. Which fuel tank type requires a complete secondary barrier?

A. A tank for compressed natural gas
B. Type C independent tank
C. Type B independent tank
D. Type A independent tank

Answer: D — Type A independent tank

Type A independent tanks are designed mainly by classical structural analysis, so any failure must be contained; a complete secondary barrier is therefore required. Type B needs only a partial barrier and Type C none.

18. In general, the maximum filling limit of an LNG fuel tank at the reference temperature is:

A. 100%
B. 90%
C. 98%
D. 95%

Answer: C — 98%

The IGF Code limits filling of liquefied gas fuel tanks so that the tank is not more than 98% liquid-full at the reference temperature, leaving vapour space for thermal expansion; the loading limit is derived from this.

19. LNG fuel is normally stored on board in which condition?

A. At ambient temperature and about 200-250 bar
B. Dissolved in a liquid carrier
C. Cryogenic, at about -162°C and near atmospheric or moderate pressure
D. At ambient temperature and atmospheric pressure

Answer: C — Cryogenic, at about -162°C and near atmospheric or moderate pressure

LNG is stored as a cryogenic liquid at around its boiling point of -162°C in insulated tanks at low or moderate pressure; compressed natural gas, by contrast, is stored as a gas at high pressure.

20. Fuel tank pressure relief valve vent outlets on open deck shall be located at a height not less than:

A. 2 m above the weather deck
B. 1 m above the tank dome
C. B/5 or 3 m, whichever is less, above the weather deck
D. B/3 or 6 m, whichever is greater, above the weather deck

Answer: D — B/3 or 6 m, whichever is greater, above the weather deck

The IGF Code requires vent mast outlets to be at least B/3 or 6 m, whichever is greater, above the weather deck and 6 m above working areas and gangways, so that released gas disperses safely.

21. What is the purpose of a tank connection space on an IGF ship?

A. To enclose all tank connections, flanges and tank valves so that leakage is contained
B. To store spare parts for the fuel system
C. To house the ballast pumps
D. To provide accommodation for the bunkering crew

Answer: A — To enclose all tank connections, flanges and tank valves so that leakage is contained

A tank connection space surrounds tank connections, flanges and valves; it is gas-tight, designed to contain cryogenic leakage, and fitted with gas detection, ventilation and a bilge well arrangement.

22. Which material is suitable for piping and tanks in contact with LNG at -162°C?

A. Austenitic stainless steel
B. Galvanised steel
C. Ordinary mild carbon steel
D. Cast iron

Answer: A — Austenitic stainless steel

Materials for cryogenic service must retain toughness at very low temperature; austenitic stainless steel, 9% nickel steel, aluminium alloys and Invar are used. Ordinary carbon steel becomes brittle and may fracture on contact with LNG.

23. Compressed natural gas (CNG) is typically stored on board ships at a pressure of about:

A. 30-40 bar
B. 200-250 bar
C. 5-10 bar
D. 1 bar

Answer: B — 200-250 bar

CNG is natural gas stored in the gaseous state compressed to high pressure, typically around 200-250 bar, in cylinders or pressure vessels; it is not cooled to cryogenic temperatures like LNG.

24. Where must the master gas fuel valve be located for each gas-consuming machinery space?

A. Inside the fuel tank
B. Outside the machinery space
C. Directly on the engine
D. Inside the engine control room

Answer: B — Outside the machinery space

The IGF Code requires an automatically operated master gas fuel valve in the gas supply line to each machinery space, located outside that space, so that the gas supply can be shut off before it enters the space.

25. What is a 'double block and bleed' valve arrangement in a gas supply line to a consumer?

A. A pressure regulator with a relief valve
B. Two manual valves in parallel
C. A single shut-off valve with a non-return valve
D. Two automatic shut-off valves in series with an automatic vent valve between them

Answer: D — Two automatic shut-off valves in series with an automatic vent valve between them

Each gas consumer is fitted with two automatic shut-off valves in series with a vent (bleed) valve between them; when the shut-off valves close, the bleed opens to vent trapped gas to a safe location.

26. In a gas-safe machinery space concept, gas fuel piping within the space is:

A. Enclosed in a gas-tight enclosure such as double-walled piping or a ventilated duct
B. Installed only above the engine
C. Single-walled and unprotected
D. Painted yellow and uninsulated

Answer: A — Enclosed in a gas-tight enclosure such as double-walled piping or a ventilated duct

In a gas-safe machinery space all gas supply piping is enclosed in a gas-tight enclosure, typically double-walled pipe or a ventilated duct, so the space is considered gas safe under all conditions.

27. What happens when gas is detected in the annular space of double-walled gas fuel piping at the shutdown level?

A. The engine speed is increased
B. The master gas fuel valve closes automatically
C. The ventilation is stopped
D. An alarm only is given and gas supply continues

Answer: B — The master gas fuel valve closes automatically

Gas detection in the annular space of double-walled piping indicates a leak in the inner pipe; the safety system automatically closes the master gas fuel valve to isolate the gas supply to the machinery space.

28. In a low-pressure dual-fuel engine operating in gas mode, ignition of the gas-air mixture is normally achieved by:

A. The heat of the scavenge air alone
B. An external flame torch
C. Hot surface ignition from the exhaust valve
D. A small quantity of pilot fuel oil injected into the cylinder

Answer: D — A small quantity of pilot fuel oil injected into the cylinder

Dual-fuel engines in gas mode generally use a small injection of pilot fuel oil, which auto-ignites by compression and in turn ignites the lean gas-air mixture.

29. If the gas supply to a dual-fuel engine fails or a gas safety trip occurs during gas-mode operation, the engine normally:

A. Continues running on air only
B. Changes over automatically to liquid fuel operation
C. Switches to steam operation
D. Stops permanently and cannot be restarted

Answer: B — Changes over automatically to liquid fuel operation

Dual-fuel engines are designed so that on a gas trip the master gas valve and double block valves close and the engine changes over automatically to fuel oil, maintaining propulsion and power.

30. What is the function of a vaporiser in an LNG fuel gas supply system?

A. To remove water from the fuel oil
B. To convert liquid LNG into gas for supply to the engines
C. To cool the gas before it enters the tank
D. To compress air for starting the engine

Answer: B — To convert liquid LNG into gas for supply to the engines

LNG must be gasified before supply to consumers; the vaporiser heats the liquid, typically using a glycol-water or steam heating medium, and the gas is then heated further to the required supply temperature.

Set 8 — 30 BIGF exit exam questions with answers

1. Before maintenance work is carried out on gas fuel piping, the piping should be:

A. Heated with a torch to remove gas
B. Opened while still under gas pressure
C. Flushed with fresh water
D. Isolated, depressurised and purged with inert gas, then gas-tested

Answer: D — Isolated, depressurised and purged with inert gas, then gas-tested

Gas fuel piping must be isolated and depressurised, then purged with an inert gas such as nitrogen and tested gas-free before being opened, to avoid releasing flammable gas or creating an explosive mixture.

2. A gas valve unit (GVU) installed ahead of a gas engine typically contains:

A. Shut-off and vent valves, filter and gas pressure control equipment
B. The main lubricating oil pump
C. The ballast control valves
D. The engine turbocharger

Answer: A — Shut-off and vent valves, filter and gas pressure control equipment

The gas valve unit, in a gas-tight enclosure, contains the double block and bleed valves, filter, pressure regulation and inerting connections, controlling the gas supplied to the engine.

3. Why is inert gas (nitrogen) used to purge gas fuel piping after an engine stops running on gas?

A. To remove remaining fuel gas and prevent a flammable mixture forming
B. To cool the engine cylinders
C. To increase fuel efficiency
D. To lubricate the piping

Answer: A — To remove remaining fuel gas and prevent a flammable mixture forming

Purging with nitrogen displaces residual gas from pipes and engine gas systems so that no flammable gas remains and air cannot later mix with gas to form a flammable atmosphere.

4. Why is a drip tray of stainless steel fitted below the LNG bunkering manifold connections?

A. To catch lubricating oil from the hose crane
B. To collect rainwater
C. To support the weight of the bunker hose
D. To collect any cryogenic leakage and protect the deck steel from brittle fracture

Answer: D — To collect any cryogenic leakage and protect the deck steel from brittle fracture

LNG at -162°C would make ordinary hull steel brittle; a stainless-steel drip tray under the bunkering connections collects any leakage and can be drained overboard safely, protecting the deck structure.

5. What is the purpose of a water curtain applied to the ship's side during LNG bunkering?

A. To cool the bunker hose
B. To protect the hull from cold-induced brittle fracture in case of LNG leakage
C. To keep the bunker barge away
D. To reduce noise from the transfer pump

Answer: B — To protect the hull from cold-induced brittle fracture in case of LNG leakage

A water curtain flowing over the hull below the bunkering connections warms and protects the steel plating, preventing brittle fracture should cryogenic LNG leak or spill onto the hull.

6. Which device allows the bunker hose to separate quickly with minimum spillage if the ship drifts away from the bunkering facility?

A. Strainer
B. Insulating flange
C. Reducing spool piece
D. Emergency release coupling (ERC)

Answer: D — Emergency release coupling (ERC)

An emergency release coupling or emergency release system parts automatically or on command when excessive movement occurs, closing valves on both sides of the break so that only minimal LNG is released.

7. What is the main purpose of the ship-shore link used during LNG bunkering?

A. To allow an emergency shutdown on either side to stop the transfer on both sides
B. To transmit tank calibration tables
C. To provide shore electrical power
D. To moor the ship

Answer: A — To allow an emergency shutdown on either side to stop the transfer on both sides

The ship-shore (or ship-ship) ESD link connects the safety systems of both parties so that activation of an emergency shutdown on either side stops pumps and closes ESD valves on both sides.

8. Which ISO standard specifies requirements for LNG bunkering transfer systems and equipment used to bunker LNG-fuelled vessels?

A. ISO 45001
B. ISO 9001
C. ISO 20519
D. ISO 14001

Answer: C — ISO 20519

ISO 20519 covers the specification for bunkering of liquefied natural gas fuelled vessels, including transfer systems, equipment, safety zones and bunkering procedures; it is widely referenced alongside SGMF guidance.

9. Before connection, the bunker manifold and transfer hoses are normally:

A. Filled with fresh water
B. Left open to atmosphere
C. Inerted with nitrogen and leak tested
D. Heated with steam

Answer: C — Inerted with nitrogen and leak tested

The transfer system is purged with nitrogen to remove oxygen and leak-tested before LNG is introduced, preventing a flammable mixture in the lines and identifying leaks at the connections.

10. After completion of LNG bunkering and before disconnection, the bunker lines should be:

A. Disconnected immediately while still full of LNG
B. Filled with sea water
C. Drained of liquid and purged with inert gas
D. Pressurised with compressed air

Answer: C — Drained of liquid and purged with inert gas

After transfer, liquid is drained or stripped from the lines and they are purged with nitrogen until hydrocarbon content is acceptable, so that no LNG or vapour is released when couplings are disconnected.

11. Which document is jointly completed by the receiving ship and the bunker supplier before LNG bunkering starts?

A. The Oil Record Book Part I
B. The garbage record book
C. A bunkering safety checklist
D. The cargo manifest

Answer: C — A bunkering safety checklist

A pre-transfer bunkering checklist, such as the IAPH or SGMF LNG bunkering checklist, is completed and agreed by both parties to confirm communications, ESD, safety zones, equipment and procedures before transfer.

12. During LNG bunkering, entry into the designated hazardous safety zone around the bunkering connections should be restricted to:

A. Essential personnel involved in the bunkering operation
B. Visitors and contractors
C. Any crew member off duty
D. Shore sightseers

Answer: A — Essential personnel involved in the bunkering operation

The safety zone around the bunker transfer is controlled: only essential, trained personnel are allowed, and ignition sources and unrelated activities are excluded for the duration of the transfer.

13. What is a 'rapid phase transition' (RPT) when LNG is spilled on water?

A. Polymerisation of methane
B. Freezing of the sea water into ice
C. A slow evaporation over several days
D. An explosive vaporisation of LNG caused by sudden heat transfer from the water, without combustion

Answer: D — An explosive vaporisation of LNG caused by sudden heat transfer from the water, without combustion

When LNG contacts water, the rapid heat transfer can cause an almost instant change from liquid to vapour, producing a physical overpressure (a cold explosion) without any combustion taking place.

14. 'Rollover' in an LNG fuel tank is caused by:

A. Sudden mixing of stratified layers of LNG of different densities, releasing a large quantity of vapour
B. Excessive ship rolling in heavy weather
C. Overfilling of the tank above 98%
D. Ingress of inert gas

Answer: A — Sudden mixing of stratified layers of LNG of different densities, releasing a large quantity of vapour

When LNG of different density or composition forms stratified layers, the lower layer heats up; when the densities equalise the layers mix suddenly, releasing large amounts of boil-off and causing a rapid pressure rise.

15. As LNG 'weathers' or ages during storage, its composition changes because:

A. Lighter components such as nitrogen and methane boil off first, leaving heavier hydrocarbons
B. Water condenses into the tank
C. The methane reacts with the tank steel
D. Heavier hydrocarbons evaporate first

Answer: A — Lighter components such as nitrogen and methane boil off first, leaving heavier hydrocarbons

Nitrogen and methane have the lowest boiling points and boil off preferentially, so aged LNG becomes denser and richer in ethane and heavier components, affecting engine knock resistance and stratification risk.

16. Why is cold methane vapour released from an LNG spill initially hazardous at deck level?

A. It is heavier than air until it warms up, so it spreads along the deck
B. It is always lighter than air and rises immediately
C. It is toxic at very low concentrations
D. It ignites spontaneously at ambient temperature

Answer: A — It is heavier than air until it warms up, so it spreads along the deck

Methane is lighter than air at ambient temperature, but vapour from boiling LNG is very cold and denser than air until it warms (around -110°C), so it forms a low-lying visible vapour cloud that can drift.

17. In hazardous area classification, a Zone 0 area is one in which:

A. No explosive gas atmosphere can ever occur
B. An explosive gas atmosphere is not likely to occur, and only for short periods
C. An explosive gas atmosphere is present continuously or for long periods
D. An explosive gas atmosphere is likely to occur occasionally in normal operation

Answer: C — An explosive gas atmosphere is present continuously or for long periods

Zone 0 has a continuous or long-duration explosive atmosphere, such as the interior of fuel tanks; Zone 1 is likely in normal operation and Zone 2 is not likely in normal operation and only for short periods.

18. Which type of electrical equipment protection is generally the only type permitted inside Zone 0 areas?

A. Ordinary industrial (IP54)
B. Flameproof (Ex d)
C. Intrinsically safe (Ex ia)
D. Increased safety (Ex e)

Answer: C — Intrinsically safe (Ex ia)

In Zone 0 only intrinsically safe equipment of category 'ia' is generally permitted, because its circuits cannot produce sparks or temperatures able to ignite the gas even with faults.

19. Why are spaces containing gas fuel equipment, such as fuel preparation rooms, kept at a lower pressure than adjacent non-hazardous spaces?

A. To reduce fuel boil-off
B. To assist with tank cooling
C. So that any leakage flows into the hazardous space and is extracted, not into safe areas
D. To increase the flow rate of the fuel pumps

Answer: C — So that any leakage flows into the hazardous space and is extracted, not into safe areas

Ventilation of hazardous spaces maintains under-pressure relative to surrounding non-hazardous spaces, ensuring any leakage stays within the hazardous space and is drawn out by exhaust fans to a safe location.

20. Why are gas fuel tanks and piping on IGF ships electrically bonded and earthed?

A. To prevent build-up of static electricity that could ignite gas
B. To reduce corrosion of the hull
C. To allow cathodic protection of the tanks
D. To improve the accuracy of level gauges

Answer: A — To prevent build-up of static electricity that could ignite gas

Bonding and earthing prevent differences in electrostatic potential between components; a static discharge spark in a flammable atmosphere could cause ignition, so anti-static measures are a key hazard control.

21. How many sections does a Safety Data Sheet prepared in the GHS format contain?

A. 12
B. 10
C. 20
D. 16

Answer: D — 16

The Globally Harmonized System (GHS) format for a Safety Data Sheet has 16 standard sections in a fixed order, from identification of the substance through to other information, so that crew can find data quickly.

22. In a GHS-format Safety Data Sheet, first-aid measures are found in section:

A. 4
B. 2
C. 11
D. 8

Answer: A — 4

Section 4 of a 16-section SDS gives first-aid measures, describing symptoms and the immediate treatment for inhalation, skin contact, eye contact and ingestion, plus any notes for medical personnel.

23. Which section of a GHS Safety Data Sheet gives suitable extinguishing media and special fire-fighting hazards?

A. Section 14
B. Section 5
C. Section 9
D. Section 3

Answer: B — Section 5

Section 5, fire-fighting measures, lists suitable and unsuitable extinguishing media, specific hazards arising from the substance in a fire and protective equipment and precautions for fire-fighters.

24. Where in a GHS Safety Data Sheet would you find occupational exposure limits and the personal protective equipment required?

A. Section 8 - Exposure controls/personal protection
B. Section 1 - Identification
C. Section 6 - Accidental release measures
D. Section 13 - Disposal considerations

Answer: A — Section 8 - Exposure controls/personal protection

Section 8 states occupational exposure limits and the engineering controls and personal protective equipment, including respiratory, hand, eye and skin protection, needed when handling the substance.

25. Which SDS section gives physical data such as boiling point, flash point, flammability limits and vapour pressure of a fuel?

A. Section 9 - Physical and chemical properties
B. Section 7 - Handling and storage
C. Section 2 - Hazards identification
D. Section 15 - Regulatory information

Answer: A — Section 9 - Physical and chemical properties

Section 9 of the SDS lists physical and chemical properties including appearance, boiling point, flash point, upper/lower flammability limits, vapour pressure and density, used to assess the fuel's hazards.

26. Why should the Safety Data Sheet for the bunkered fuel be available on board before a bunkering operation?

A. Because it contains the ship's stability data
B. Because it is needed for customs clearance only
C. Because it replaces the bunker delivery note
D. So that crew know the hazards, required PPE and emergency and first-aid measures for that fuel

Answer: D — So that crew know the hazards, required PPE and emergency and first-aid measures for that fuel

The SDS provides the hazard information, handling precautions, PPE, fire-fighting, spill and first-aid measures for the specific fuel, and must be available for planning and emergency response during bunkering.

27. In a GHS Safety Data Sheet, the classification of the substance and its hazard pictograms and statements appear in:

A. Section 10 - Stability and reactivity
B. Section 12 - Ecological information
C. Section 16 - Other information
D. Section 2 - Hazards identification

Answer: D — Section 2 - Hazards identification

Section 2, hazards identification, gives the GHS classification, label elements such as pictograms, signal word and hazard and precautionary statements, and other hazards of the substance.

28. Why may a catalytic (pellistor) combustible gas detector give a false low reading in an inerted atmosphere?

A. It works only at cryogenic temperatures
B. It needs sufficient oxygen to burn the gas on its sensing element
C. It measures only carbon dioxide
D. It is sensitive only to toxic gases

Answer: B — It needs sufficient oxygen to burn the gas on its sensing element

A catalytic sensor measures heat from oxidising gas on a heated element and needs oxygen to work; in oxygen-deficient or inert atmospheres it can under-read, so infrared instruments or tankscopes are used instead.

29. Before using a portable gas detector to test a space, the user should:

A. Use it without checks if the battery light is on
B. Expose it to fresh air only
C. Shake the instrument to activate it
D. Check it is in calibration and carry out a function (bump) test with a known test gas

Answer: D — Check it is in calibration and carry out a function (bump) test with a known test gas

Gas detectors must be within their calibration period and should be bump-tested with a known span gas before use to confirm sensors and alarms respond correctly; an unchecked instrument may give dangerously wrong readings.

30. A typical personal multi-gas detector worn on an IGF ship monitors:

A. Only humidity
B. Only noise level
C. Only radiation
D. Oxygen, flammable gas (% LEL), carbon monoxide and hydrogen sulphide

Answer: D — Oxygen, flammable gas (% LEL), carbon monoxide and hydrogen sulphide

Personal four-gas detectors normally measure oxygen, combustible gas as a percentage of LEL, carbon monoxide and hydrogen sulphide, giving an alarm to the wearer when set levels are reached.

Set 9 — 30 BIGF exit exam questions with answers

1. According to the IGF Code, fixed gas detection systems generally give an alarm at a gas concentration of:

A. 50% of the lower explosion limit
B. 100% of the lower explosion limit
C. 5% of the lower explosion limit
D. 20% of the lower explosion limit

Answer: D — 20% of the lower explosion limit

The IGF Code requires an audible and visual alarm when gas concentration reaches 20% LEL, with safety actions such as shutdown of gas supply typically initiated at 40% LEL, giving warning well before a flammable mixture forms.

2. Which personal protective equipment is most appropriate when there is a risk of contact with LNG liquid during bunkering?

A. Rubber boots only
B. Ordinary cotton gloves and safety glasses
C. A chemical suit made of PVC with no thermal insulation
D. Cryogenic gloves, face shield and protective clothing that resists cold liquid

Answer: D — Cryogenic gloves, face shield and protective clothing that resists cold liquid

Contact with LNG causes severe cold burns, so loose-fitting cryogenic gloves, a full face shield or goggles and protective clothing suited for cryogenic splashes are worn by personnel at the bunkering manifold.

3. What is the main purpose of an emergency escape breathing device (EEBD)?

A. To allow a person to escape from a hazardous atmosphere
B. To rescue a casualty from a fuel tank
C. To carry out tank entry for maintenance
D. To fight a fire in an enclosed space

Answer: A — To allow a person to escape from a hazardous atmosphere

An EEBD is a supplied-air or oxygen device used only for escape from a compartment with a hazardous atmosphere; it must not be used for fire-fighting, entry into oxygen-deficient spaces or rescue work.

4. Which instrument is used to measure the hydrocarbon content of an atmosphere containing little or no oxygen, such as an inerted fuel tank?

A. Infrared gas analyser or tankscope
B. Catalytic explosimeter
C. Hygrometer
D. Smoke detector

Answer: A — Infrared gas analyser or tankscope

Infrared analysers and tankscopes measure hydrocarbon percentage by volume without needing oxygen, making them suitable for inerted atmospheres where catalytic explosimeters would give unreliable readings.

5. Equipment for rescuing a casualty from a fuel tank or other enclosed space on an IGF ship includes:

A. A lifebuoy with self-igniting light
B. A line-throwing appliance
C. Breathing apparatus, rescue harness, lifeline and hoisting arrangement
D. A portable fire extinguisher only

Answer: C — Breathing apparatus, rescue harness, lifeline and hoisting arrangement

Tank evacuation and rescue require self-contained breathing apparatus for rescuers, a harness and lifeline, and a tripod or hoisting device or stretcher to lift the casualty out of the space.

6. Before entry into an enclosed space, the atmosphere should be tested and confirmed to have:

A. 21% oxygen by volume and not more than 1% of the LFL
B. Flammable gas below 50% of the LFL
C. At least 15% oxygen
D. Oxygen of 25% by volume

Answer: A — 21% oxygen by volume and not more than 1% of the LFL

IMO Resolution A.1050(27) on enclosed space entry recommends that the atmosphere has 21% oxygen by volume, not more than 1% of the LFL of flammable vapour and toxic gases below their occupational exposure limits.

7. Hot work in or near a hazardous area on an IGF ship may only be carried out:

A. At night when fewer people are working
B. Under a hot work permit after gas testing, isolation of fuel systems and fire precautions
C. Whenever the chief engineer is on board
D. Without a permit if the job is short

Answer: B — Under a hot work permit after gas testing, isolation of fuel systems and fire precautions

Hot work near gas fuel systems requires a hot work permit under the SMS, with the area isolated and gas-freed, atmosphere tested, fire-fighting equipment ready and a fire watch posted throughout the work.

8. During entry into an enclosed space, the atmosphere should be:

A. Tested only after the work is completed
B. Left unventilated to save energy
C. Monitored continuously or at regular intervals and the space ventilated
D. Tested only once before entry

Answer: C — Monitored continuously or at regular intervals and the space ventilated

Conditions may change during work, so the atmosphere is monitored continuously or frequently while personnel are inside, and ventilation is maintained throughout to keep oxygen and gas levels safe.

9. What is the role of the attendant stationed at the entrance of an enclosed space during entry?

A. To leave once the entrants are inside
B. To monitor the entrants, maintain communication and raise the alarm if needed
C. To enter the space immediately to help if anyone collapses
D. To carry out gas tests inside the space

Answer: B — To monitor the entrants, maintain communication and raise the alarm if needed

The attendant stays at the entrance, keeps communication with those inside and raises the alarm in an emergency; they must not enter to rescue without proper backup and breathing apparatus.

10. Before work is carried out on a gas fuel system on an IGF ship, the permit to work should require that:

A. The gas detection system is disconnected
B. The system remains pressurised for testing
C. The ventilation is switched off
D. The system is isolated, depressurised, purged and verified gas free

Answer: D — The system is isolated, depressurised, purged and verified gas free

A permit to work for fuel system maintenance ensures isolation of the section, depressurisation, inert gas purging and gas testing, plus locking and tagging of isolations, before any flange or component is opened.

11. Why is a permit to work system used for work on fuel systems?

A. To speed up maintenance work
B. To ensure hazards are identified and controls verified and authorised before work begins
C. To replace the risk assessment
D. To record crew overtime

Answer: B — To ensure hazards are identified and controls verified and authorised before work begins

A permit to work formally confirms that hazards are assessed, isolations and safety precautions are in place and the work is authorised by a responsible officer, and that the system is safely restored afterwards.

12. Which precaution is important when carrying out cold work, such as opening a flange, in a gas-hazardous area?

A. No precautions are needed as no heat is involved
B. Use a permit, ensure the line is isolated and gas free, and monitor the atmosphere
C. Carry out the work while gas is flowing to detect leaks
D. Use compressed air to blow out the line

Answer: B — Use a permit, ensure the line is isolated and gas free, and monitor the atmosphere

Cold work in hazardous areas can still release gas or create sparks; a permit, isolation, gas freeing and atmosphere monitoring are needed, with suitable PPE and tools appropriate to the hazard.

13. Why must a risk assessment be carried out before non-routine maintenance on IGF fuel systems?

A. To identify hazards such as gas release and cold liquid, and to put appropriate controls in place
B. Only to satisfy port state control
C. To determine the crew wage
D. Because it removes the need for a permit to work

Answer: A — To identify hazards such as gas release and cold liquid, and to put appropriate controls in place

Under the ISM Code and IGF ship SMS, risk assessment identifies hazards such as flammable gas, cryogenic liquid and pressure release, and sets controls before work starts, supporting the permit to work system.

14. What is the correct first-aid treatment for a cold burn caused by contact with LNG?

A. Apply hot water above 60°C
B. Gently warm the affected area with lukewarm water and do not rub it
C. Apply oil-based ointment and keep the area cold
D. Rub the affected area vigorously with snow

Answer: B — Gently warm the affected area with lukewarm water and do not rub it

Cold burns should be thawed gently, for example with lukewarm water; rubbing or applying direct heat damages tissue further. The area is then covered loosely with a sterile dressing and medical advice obtained.

15. Clothing frozen to the skin after contact with cryogenic liquid should:

A. Be pulled off immediately
B. Not be pulled off; thaw it with lukewarm water first
C. Be left on and the casualty kept cold
D. Be cut away with a hot knife

Answer: B — Not be pulled off; thaw it with lukewarm water first

Removing frozen clothing can tear skin, so it should be loosened by gentle thawing with lukewarm water; loose clothing that is not frozen may be removed to allow warming of the affected area.

16. A crew member is found unconscious in a space where nitrogen has leaked. After the casualty is removed to fresh air by properly equipped rescuers, what is the first priority?

A. Leave the casualty to recover alone
B. Wait for the ship's doctor before doing anything
C. Check breathing and start CPR if not breathing normally, giving oxygen when available
D. Give the casualty water to drink

Answer: C — Check breathing and start CPR if not breathing normally, giving oxygen when available

Nitrogen causes asphyxiation by displacing oxygen. Once rescued, the casualty's airway and breathing are checked; if not breathing normally, CPR is started immediately, and oxygen is given and medical advice sought.

17. What is the recommended first aid for eye contact with a cold liquefied gas or a chemical fuel such as methanol?

A. Cover the eye and do nothing else
B. Apply eye ointment immediately without rinsing
C. Irrigate the eye with plenty of clean water for at least 15 minutes and obtain medical advice
D. Rub the eye to remove the liquid

Answer: C — Irrigate the eye with plenty of clean water for at least 15 minutes and obtain medical advice

Eyes should be flushed gently with copious clean (lukewarm for cold burns) water for at least 15 minutes, keeping the eyelids open, and medical advice obtained, as indicated in the SDS and MFAG.

18. Which IMO publication provides medical first aid guidance for accidents involving dangerous goods and is used together with the SDS?

A. IAMSAR Manual
B. Medical First Aid Guide (MFAG)
C. Cargo Securing Manual
D. International Code of Signals

Answer: B — Medical First Aid Guide (MFAG)

The Medical First Aid Guide for Use in Accidents Involving Dangerous Goods (MFAG) gives treatment guidance for chemical exposure, used together with the substance-specific first-aid information in the SDS.

19. What is a serious health effect of swallowing methanol fuel?

A. No effect, as methanol is non-toxic
B. Immediate cold burns to the mouth
C. Only mild stomach upset
D. Damage to the optic nerve leading to blindness, and possibly death

Answer: D — Damage to the optic nerve leading to blindness, and possibly death

Methanol is toxic by ingestion, inhalation and skin absorption; it is metabolised to formaldehyde and formic acid, which can cause metabolic acidosis, blindness and death, so urgent medical treatment is required.

20. What are typical early symptoms of oxygen deficiency caused by inhalation of methane or nitrogen?

A. Increased alertness
B. Watering eyes and severe coughing only
C. Rapid breathing, dizziness, loss of coordination and confusion
D. Skin rash and itching

Answer: C — Rapid breathing, dizziness, loss of coordination and confusion

Asphyxiant gases reduce oxygen available to the body, causing rapid breathing, fatigue, dizziness, poor judgement and loss of coordination, followed by unconsciousness and death if the casualty is not removed.

21. When treating a casualty for frostbite after exposure to cold gas, which action should be avoided?

A. Applying direct heat such as a heater or hot water bottle to the affected area
B. Removing the casualty from the cold source
C. Loosening tight clothing
D. Seeking medical advice

Answer: A — Applying direct heat such as a heater or hot water bottle to the affected area

Frostbitten tissue is easily damaged; direct heat can burn the numb area and rubbing worsens injury. Gentle rewarming, loose dressing and medical advice are recommended instead.

22. Methanol absorbed through the skin is a hazard because:

A. It causes cold burns at room temperature
B. It causes immediate asphyxiation
C. It is toxic and can be absorbed through intact skin
D. It is radioactive

Answer: C — It is toxic and can be absorbed through intact skin

Methanol is classified as toxic by skin contact as well as by inhalation and ingestion, so skin contact should be avoided by using suitable gloves and clothing, and contaminated skin washed with plenty of water.

23. What is the most important first action when dealing with a gas fuel fire fed by a leak?

A. Open all doors to ventilate the space
B. Extinguish the flame immediately with water jets
C. Cover the flame with a blanket
D. Isolate the source of gas to stop the fuel supply

Answer: D — Isolate the source of gas to stop the fuel supply

A gas fire should be controlled by shutting off the gas supply. If a gas fire is extinguished while gas is still escaping, the gas cloud may spread and re-ignite explosively, so isolation is the priority.

24. Why should a gas fire normally not be extinguished unless the gas supply can be isolated?

A. Extinguishing agents react with methane
B. Escaping unburnt gas may form a vapour cloud that can explode on re-ignition
C. It is illegal to extinguish gas fires
D. The fire will go out by itself within seconds

Answer: B — Escaping unburnt gas may form a vapour cloud that can explode on re-ignition

While the leak continues, burning gas is safer than unburnt gas accumulating; a vapour cloud may re-ignite with a much more severe explosion, so surrounding areas are cooled until the gas is isolated.

25. Which extinguishing agent is most effective for putting out a gas jet fire at the bunkering station?

A. Water jet
B. Dry chemical powder
C. Carbon dioxide from a portable extinguisher in open air
D. Sand

Answer: B — Dry chemical powder

Dry chemical powder interrupts the combustion chain reaction and is effective on gas jet fires; the IGF Code requires a fixed dry chemical powder system covering the bunkering station area.

26. What is the main role of the water spray system covering fuel storage tanks on open deck?

A. Cooling and fire protection of the tank surfaces exposed to fire
B. Extinguishing an LNG pool fire
C. Filling the tank in an emergency
D. Washing the deck after bunkering

Answer: A — Cooling and fire protection of the tank surfaces exposed to fire

The IGF Code requires a water spray system for cooling and fire prevention to cover exposed parts of fuel tanks on open deck, protecting the tanks from heat radiation and reducing the risk of failure or BLEVE.

27. Why should water not be applied directly onto a pool of spilled LNG?

A. It causes the LNG to freeze into a solid
B. It reduces the visibility of the cloud
C. It reacts chemically to form a toxic gas
D. It increases the rate of vaporisation of the LNG

Answer: D — It increases the rate of vaporisation of the LNG

Water is far warmer than LNG and adds heat to the pool, greatly increasing boil-off and vapour release; water is instead used to cool surrounding structures and to protect personnel.

28. Which agent is used to control vapour release and radiant heat from an LNG pool fire on deck or in a drip tray?

A. Water jet
B. High-expansion foam
C. Seawater from the fire main applied directly
D. Steam

Answer: B — High-expansion foam

High-expansion foam blankets the LNG pool, reducing vaporisation and radiant heat from the fire, although it does not extinguish it completely; the spill is allowed to burn off in a controlled way.

29. Which extinguishing medium is recommended for a methanol fuel fire?

A. High-pressure water jet only
B. Ordinary protein foam
C. Alcohol-resistant foam
D. Sand

Answer: C — Alcohol-resistant foam

Methanol is water-miscible and destroys ordinary foam blankets, so alcohol-resistant foam is used; water spray can dilute and cool, and dry powder may be used for small fires.

30. What special hazard of a methanol fire makes it difficult to detect?

A. It produces a loud explosion when it starts
B. It produces thick black smoke
C. It burns with an almost invisible flame in daylight
D. It burns only at night

Answer: C — It burns with an almost invisible flame in daylight

Methanol burns with a pale blue, nearly invisible flame in daylight, so fires may go unnoticed; heat detection, thermal imaging cameras and careful approach are needed when responding.

Set 10 — 30 BIGF exit exam questions with answers

1. Fire-fighters approaching a gas fire should protect themselves by:

A. Using a straight water jet directly on the flame
B. Using water spray as a shield and approaching from upwind
C. Approaching from downwind
D. Wearing only normal working clothes

Answer: B — Using water spray as a shield and approaching from upwind

Approaching from upwind keeps fire-fighters out of the gas cloud and smoke, and water spray provides a heat shield against radiant heat while they move to isolate valves or apply dry powder.

2. Which condition will typically initiate an automatic shutdown of gas supply to an ESD-protected machinery space?

A. High sea water temperature
B. Low lubricating oil level in the purifier
C. Gas detection in the space at 40% LEL
D. Normal change of watch

Answer: C — Gas detection in the space at 40% LEL

In an ESD-protected machinery space, gas detection at the shutdown level (40% LEL) or fire detection automatically shuts off the gas supply and disconnects non-certified equipment, as required by the IGF Code.

3. Loss of ventilation in the annular space of double-walled gas fuel piping will result in:

A. No action, as ventilation is not important
B. Increase in engine power
C. Stopping of the bilge pumps
D. Automatic closure of the master gas fuel valve

Answer: D — Automatic closure of the master gas fuel valve

Ventilation of the double-wall annular space ensures any leak is detected and removed; loss of this ventilation removes a safety barrier, so the IGF Code requires automatic shutdown of the master gas fuel valve.

4. What action does an ESD of the bunkering system perform?

A. Stops transfer pumps and closes the bunkering manifold ESD valves
B. Starts the emergency generator only
C. Releases the anchor
D. Opens all tank relief valves

Answer: A — Stops transfer pumps and closes the bunkering manifold ESD valves

Bunkering ESD stops transfer pumps and closes the ESD valves on the manifold and supply side, isolating the transfer system to minimise any release of LNG in an emergency.

5. If a gas leak is discovered on deck during bunkering, the immediate action should be to:

A. Continue bunkering and repair the leak later
B. Open the bunker manifold drain to atmosphere
C. Activate the ESD, raise the alarm and stop the transfer
D. Use the ship's crane to move the hose

Answer: C — Activate the ESD, raise the alarm and stop the transfer

On detection of a leak during bunkering, the ESD is activated to stop the transfer and isolate the lines, the alarm is raised, and the emergency plan is followed, including keeping personnel clear of the vapour cloud.

6. High liquid level in an LNG fuel tank during bunkering will typically cause:

A. Opening of the tank relief valve
B. Stopping of the main engine
C. Starting of the water spray
D. Automatic closure of the tank filling valve

Answer: D — Automatic closure of the tank filling valve

The IGF Code requires a high-level alarm and an independent sensor that automatically actuates a shut-off valve to prevent overfilling the tank above its maximum filling limit.

7. Where should the emergency shutdown of a bunkering operation be capable of being activated from?

A. Only from the shore
B. The bunkering control station and other designated safe locations
C. Only by hand at the manifold
D. Only from the bridge after asking the master

Answer: B — The bunkering control station and other designated safe locations

Bunkering ESD must be capable of activation from the bunkering control location and from other designated positions, and via the ship-shore link, so the operation can be stopped quickly from wherever the emergency is noticed.

8. In an emergency involving the fuel system, which document provides the ship-specific procedures to be followed?

A. The garbage management plan
B. The ship's articles of agreement
C. The ship's emergency response plan under the SMS
D. The ship's stability booklet

Answer: C — The ship's emergency response plan under the SMS

The ISM Code requires shipboard emergency plans; for IGF ships these include fuel-specific procedures for gas leaks, fire, bunkering incidents and ESD, and are practised in drills.

9. Which event in a fuel tank connection space should initiate automatic actions to close the tank valves?

A. Low ambient humidity
B. Detection of liquid leakage or gas at the shutdown level
C. Daylight conditions
D. Normal tank temperature

Answer: B — Detection of liquid leakage or gas at the shutdown level

Tank connection spaces are monitored for gas and liquid leakage (low temperature); on detection, safety systems close the tank valves to isolate the fuel and limit the release.

10. Why must emergency drills for fuel-related incidents be conducted on IGF ships?

A. To ensure crew are familiar with emergency procedures and ESD operation
B. To check the ship's speed
C. To test the endurance of crew
D. To meet commercial charter requirements only

Answer: A — To ensure crew are familiar with emergency procedures and ESD operation

Regular drills and exercises on fuel-related emergency scenarios, including leaks, fire and ESD activation, ensure the crew can respond effectively, as required under SOLAS and the ISM Code and the IGF Code operational section.

11. Activation of a fire detector in an ESD-protected machinery space where gas fuel is used will normally cause:

A. Reduced ventilation to the space
B. Starting of the fuel transfer pump
C. Automatic shutdown of the gas fuel supply to that space
D. Opening of the master gas valve

Answer: C — Automatic shutdown of the gas fuel supply to that space

Fire detection in a machinery space containing gas-fuelled consumers results in automatic closure of the master gas fuel valve to that space, removing the fuel source before fire-fighting begins.

12. Under normal operating conditions, venting of fuel gas to the atmosphere for control of LNG tank pressure is:

A. Not acceptable, except in emergency situations
B. Acceptable whenever tank pressure rises
C. Required daily
D. Acceptable only in port

Answer: A — Not acceptable, except in emergency situations

The IGF Code requires tank pressure to be controlled without venting under normal operation, using methods such as consumption of boil-off, reliquefaction, gas combustion units or pressure accumulation; venting is accepted only in emergencies.

13. Which method is commonly used to manage boil-off gas from an LNG fuel tank without releasing it to the atmosphere?

A. Storing it in the bilge
B. Consuming it in engines or a gas combustion unit
C. Mixing it with ballast water
D. Venting it from the mast

Answer: B — Consuming it in engines or a gas combustion unit

Boil-off can be burnt in the propulsion or auxiliary engines or boilers, oxidised in a gas combustion unit, reliquefied, or contained by allowing tank pressure to accumulate within design limits.

14. What is 'methane slip' in gas-fuelled engines?

A. Loss of methane during bunkering only
B. A method for cleaning gas piping
C. Leakage of LNG from tanks
D. Release of unburnt methane through the engine exhaust

Answer: D — Release of unburnt methane through the engine exhaust

Methane slip is unburnt methane passing through the combustion process and leaving with the exhaust gas, particularly in low-pressure Otto-cycle engines; because methane is a potent greenhouse gas, slip reduces the climate benefit of LNG.

15. Why should release of methane to the atmosphere be minimised?

A. Methane depletes the ozone layer
B. Methane causes acid rain
C. Methane forms oily residue on the sea
D. Methane is a much more potent greenhouse gas than carbon dioxide

Answer: D — Methane is a much more potent greenhouse gas than carbon dioxide

Methane traps far more heat per tonne than carbon dioxide over the short term, so any venting, leakage or methane slip significantly offsets the lower CO2 emissions of LNG fuel.

16. What emission benefit does using LNG as fuel give with respect to MARPOL Annex VI sulphur limits?

A. It has no effect on SOx
B. It produces virtually no sulphur oxides, meeting global and ECA sulphur limits
C. It requires an exhaust gas scrubber to meet the limits
D. It increases SOx emissions

Answer: B — It produces virtually no sulphur oxides, meeting global and ECA sulphur limits

Natural gas contains negligible sulphur, so LNG-fuelled operation produces virtually no SOx and particulates, allowing compliance with the MARPOL Annex VI 0.50% global and 0.10% ECA limits without scrubbers.

17. In the event of a small LNG spill on deck, which action helps to protect the environment and the ship?

A. Collect it in buckets
B. Cover it with sawdust
C. Wash the LNG overboard with hot water
D. Stop the leak, contain it in the drip tray and allow it to evaporate safely while protecting the steel

Answer: D — Stop the leak, contain it in the drip tray and allow it to evaporate safely while protecting the steel

Small LNG spills evaporate quickly; the leak source is isolated, liquid is contained in the drip tray or drained overboard via the designated route, water is used to protect the structure, and ignition sources are kept away.

18. Methanol spilled into the sea is an environmental concern mainly because:

A. It forms a thick oil slick
B. It freezes the surface water
C. It sinks and remains on the seabed for years
D. It is fully miscible with water and toxic to marine life in high concentrations

Answer: D — It is fully miscible with water and toxic to marine life in high concentrations

Methanol dissolves completely in water and is biodegradable, but high local concentrations are toxic to marine organisms; it cannot be recovered with booms or skimmers as with oil, so prevention of spills is essential.

19. To ensure no release occurs when the bunker hoses are connected or disconnected, what must be done to the bunker piping system first?

A. Drain it of liquid only
B. Gas it up with LNG vapour
C. Purge it with inert gas
D. None of the above

Answer: C — Purge it with inert gas

Before connecting and before disconnecting, the bunker line is purged with inert gas (normally nitrogen) so no flammable gas is released at the manifold when the connection is opened, and no air is admitted into a fuel system.

20. The compression ratio of a compressor is the ratio of the absolute ___ at the discharge to that at the suction.

A. volume
B. pressure
C. mass
D. temperature

Answer: B — pressure

Compression ratio = absolute discharge pressure ÷ absolute suction pressure. Absolute (gauge + atmospheric) values must be used, otherwise the ratio is meaningless near atmospheric suction.

21. In a gas-safe machinery space, no single failure may release gas into the space. How does the IGF Code achieve this for the gas supply piping?

A. Alarms and gas detectors only
B. Thick-walled pipes of robust construction
C. Regular leak checks of the gas pipelines
D. All gas piping is enclosed in a gas-tight double wall or ventilated duct

Answer: D — All gas piping is enclosed in a gas-tight double wall or ventilated duct

The gas-safe concept makes the space safe under all conditions: every gas pipe in the space is enclosed in a double-walled pipe or ventilated duct, so a leak from the inner pipe stays inside the enclosure, where it is detected and the gas supply is shut off. Detection and inspection support this but cannot prevent a release on their own.

22. Arrangements for gas compressors and pumps must ensure that under no circumstances ___ can be introduced into the gas control section or the gas-fuelled machinery (unless that machinery is designed to use it).

A. Heavy fuel oil
B. Liquefied gas
C. Water
D. Inert gas

Answer: B — Liquefied gas

Engines and the gas valve unit are designed to receive fuel as gas at a controlled pressure and temperature. Liquid carried over from the tank or vaporiser would flash, cause pressure surges and could damage the engine, so the fuel preparation system must make liquid carry-over impossible.

23. In a natural gas liquefaction plant, which component is removed beforehand because it would freeze and block the process?

A. Methane
B. Heavier hydrocarbons
C. Carbon dioxide
D. Ethane

Answer: C — Carbon dioxide

Carbon dioxide (with water and sulphur compounds) is removed in pre-treatment because it solidifies well above LNG temperature (about −162 °C) and would form solid deposits that block heat exchangers. Methane is the product itself.

24. True fire prevention involves which of the following?

A. Recognising fire hazards
B. Removing the hazards
C. At least reducing their potential
D. All the above

Answer: D — All the above

Fire prevention means first recognising where fuel, heat and oxygen can come together, then removing the hazard, or where that is impossible reducing its potential (for example by isolating, cooling or ventilating). All three steps belong together.

25. Personnel should not enter or work in a tank or enclosed space until it is in which condition?

A. A flammable condition
B. A safe working condition
C. An unsafe working condition
D. An oxygen-deficient condition

Answer: B — A safe working condition

Entry is allowed only once the space has been ventilated, tested (oxygen about 20.9 %, no flammable or toxic gas) and declared safe for entry under a permit, with the precautions in the entry permit in place.

26. For vertical access openings to enclosed spaces, what is the minimum clear opening required?

A. Less than 600 mm × 800 mm, at a height of more than 600 mm from the bottom
B. Not less than 600 mm × 800 mm, at a height of not more than 600 mm from the bottom
C. Less than 600 mm × 800 mm, at a height of not more than 600 mm from the bottom
D. Not less than 600 mm × 800 mm, at a height of more than 600 mm from the bottom

Answer: B — Not less than 600 mm × 800 mm, at a height of not more than 600 mm from the bottom

Vertical openings must be at least 600 mm × 800 mm and no more than 600 mm above the bottom plating, unless gratings or footholds are fitted. This lets a rescuer in breathing apparatus pass through and lets a casualty on a stretcher be brought out.

27. If portable tanks are used for fuel storage, the design of the fuel containment system shall be:

A. Equivalent to permanently installed tanks
B. Not necessarily equivalent to permanently installed tanks
C. Up to the owner's discretion
D. Dependent on the age of the vessel

Answer: A — Equivalent to permanently installed tanks

The IGF Code allows portable fuel tanks only if their design, fixing, connections and safety arrangements give the same level of safety as a permanently installed fuel tank.

28. The fuel containment system shall be designed so that a leak from the tank or its connections does not:

A. Harm persons on board
B. Endanger the ship
C. Harm the environment
D. All of the above

Answer: D — All of the above

The IGF Code requires that a leak from a fuel tank or its connections does not constitute a danger to persons on board, the environment or the ship. That is why tank connections sit in tank connection spaces with gas detection, drip trays and ventilation.

29. A set of two valves in series in a pipe, with a third valve that releases the pressure from the pipe between them, is known as:

A. Double blow and bleed valve
B. Double blast and bleed valve
C. Double block and bleed valve
D. Double block and blow valve

Answer: C — Double block and bleed valve

Double block and bleed: two shut-off (block) valves in series with a vent (bleed) valve between them. The gas valve unit uses it so that when the engine stops on gas, the section between the blocks is vented and gas cannot leak past into the engine.

30. The probability of a gas explosion in a machinery space with ___ fuelled machinery shall be minimised. (a) gas (b) low-flashpoint fuel

A. Gas only
B. Low-flashpoint fuel only
C. None of the above
D. Both (a) and (b)

Answer: D — Both (a) and (b)

The machinery space requirements of the IGF Code apply to machinery using gas or other low-flashpoint fuels. In both cases the aim is to minimise the probability of an explosion, by gas-safe or ESD-protected arrangements.

Set 11 — 30 BIGF exit exam questions with answers

1. The ventilated duct around a gas pipe shall be pressure tested to show that it can withstand the expected ___ at gas pipe rupture.

A. Least pressure
B. Lower pressure
C. Maximum pressure
D. Minimum pressure

Answer: C — Maximum pressure

If the inner gas pipe ruptures, the duct briefly holds the escaping gas until the supply is shut off. It must therefore be tested to the maximum pressure that can build up in it at a pipe rupture.

2. In limit state design of fuel containment systems, the Accident Limit States (ALS) concern:

A. The maximum load-carrying capacity
B. Degradation due to the effect of cyclic loading
C. The ability of the structure to resist accident situations
D. None of the above

Answer: C — The ability of the structure to resist accident situations

Limit state design uses ULS (ultimate: maximum load-carrying capacity), FLS (fatigue: degradation under cyclic loading) and ALS (accident: resisting accidental situations such as collision, fire or flooding).

3. The air inlet for the mechanical ventilation of the duct or double-walled pipe around gas piping may be taken from a ___.

A. Explosive machinery space
B. Unsafe machinery space
C. Non-hazardous machinery space
D. Hazardous machinery space

Answer: C — Non-hazardous machinery space

The annular space is ventilated with clean air drawn from a non-hazardous (gas-safe) area, so that any gas detected in it can only come from a leak in the inner pipe. The outlet goes to a safe location in the open.

4. Inert gas production equipment on board shall produce ___ at no time greater than 5 per cent by volume.

A. Dry inert gas with a hydrogen content
B. Dry inert gas with an oxygen content
C. Dry inert gas with a carbon content
D. Dry inert gas with an ammonia content

Answer: B — Dry inert gas with an oxygen content

The inert gas supply must be dry, with an oxygen content at no time greater than 5 % by volume, so that an atmosphere it inerts can never become flammable. On gas-fuelled ships this is normally nitrogen from a generator.

5. Fuel tanks shall be designed to withstand the ___ of the fuel under conditions of the upper ambient design temperature.

A. Full gauge vapour pressure
B. Full absolute pressure
C. Full liquid pressure
D. Full atmospheric pressure

Answer: A — Full gauge vapour pressure

Under worst-case ambient heat the fuel's vapour pressure rises. The tank must withstand that full gauge vapour pressure, or else have pressure control that keeps the pressure within the tank's design limits.

6. Under normal operation, personnel shall not enter fuel tanks, fuel storage hold spaces, void spaces or other enclosed spaces where gas may accumulate, nor introduce any source of ignition into them, unless:

A. A risk assessment has been carried out
B. An entry permit has been signed
C. The space is certified as non-hazardous
D. The space has been certified gas-free and is maintained in that condition

Answer: D — The space has been certified gas-free and is maintained in that condition

The IGF Code forbids entry, and any potential source of ignition, unless the space has been certified gas-free and is kept gas-free (continuous ventilation and monitoring). A risk assessment or permit alone does not satisfy the rule.

7. What is the critical temperature of propane?

A. 96.8 °C
B. −82.6 °C
C. 32.2 °C
D. 152.0 °C

Answer: A — 96.8 °C

Propane's critical temperature is about 96.8 °C (critical pressure about 42.5 bar). Above this temperature it cannot be liquefied by pressure alone. The other figures are methane (−82.6 °C), ethane (32.2 °C) and n-butane (about 152 °C).

8. For fuel tanks fitted with pressure relief valves (PRVs) that can be set at more than one set pressure, what is provided for each set pressure?

A. Safe-pressure alarms
B. Medium-pressure alarms
C. High-pressure alarms
D. Low-pressure alarms

Answer: C — High-pressure alarms

When a PRV can be set to more than one pressure, a high-pressure alarm is provided for each set pressure. The crew is warned before the relief valve lifts at whichever setting is in use.

9. In the IGF Code, the secondary barrier: (a) prevents the lowering of the temperature of the ship's structure to an unsafe level; (b) is the liquid-resisting outer element of a fuel containment system that temporarily contains leakage through the primary barrier.

A. (a) only
B. (b) only
C. Both (a) and (b)
D. None of the above

Answer: C — Both (a) and (b)

The IGF Code defines the secondary barrier as the liquid-resisting outer element designed to give temporary containment of any foreseeable leakage of liquid fuel through the primary barrier, and to prevent the lowering of the temperature of the ship's structure to an unsafe level. Both statements are part of the definition.

10. In the IGF Code, IEC means:

A. International Electrotechnical Commission
B. Indian Electrochemical Commission
C. International Electrochemical Commission
D. Indian Electrotechnical Commission

Answer: A — International Electrotechnical Commission

IEC is the International Electrotechnical Commission. Its standards (such as the IEC 60079 series for explosive atmospheres) are referenced by the IGF Code for electrical equipment in hazardous areas.

11. In hazardous zones, non-sparking tools are typically made of:

A. Hardened carbon steel
B. Bronze or brass (beryllium-copper)
C. Aluminium
D. Plastic only

Answer: B — Bronze or brass (beryllium-copper)

Beryllium-copper / brass / bronze alloys are 'non-sparking'. However they are not a stand-alone control — gas-freeing, ventilation, permit-to-work and monitoring are still needed.

12. If a CO₂ extinguisher is not available for an electrical (Class C / E) fire, the most suitable alternative portable extinguisher is:

A. Water jet
B. Foam
C. Dry Chemical Powder (BC/ABC)
D. Wet chemical

Answer: C — Dry Chemical Powder (BC/ABC)

DCP is non-conductive and rapidly knocks down flames around live electrical equipment. Water and foam are conductive and unsafe for live circuits.

13. A soot/uptake fire is detected at the boiler funnel. The first action is to:

A. Increase forced-draught fan speed
B. Shut off fuel and air supply to the burner; close uptake dampers; cool surrounding structure
C. Open the boiler manhole to inspect
D. Switch off the deck water-spray

Answer: B — Shut off fuel and air supply to the burner; close uptake dampers; cool surrounding structure

Starve the fire: stop the fuel, stop the air, close dampers, and apply boundary cooling on adjacent steel. Soot blowing or water entry into a hot boiler is dangerous.

14. On a gas-fuelled ship, the high-level gas-detection alarm in a ventilated machinery space typically activates at:

A. 10 % LEL
B. 20 % LEL
C. 40 % LEL
D. 60 % LEL

Answer: B — 20 % LEL

IGF Code gas detection: an audible and visual alarm at 20 % LEL, with safety actions (shutdown, isolation) at 40 % LEL in the ventilated duct or ESD-protected space.

15. At atmospheric pressure, LNG (predominantly methane) boils at approximately:

A. −42 °C
B. −104 °C
C. −162 °C
D. −253 °C

Answer: C — −162 °C

Pure methane boils at −161.5 °C; LNG (mostly methane) is stored at ≈ −162 °C atmospheric. Propane boils at −42 °C and hydrogen at −253 °C.

16. Before entry to an enclosed space, the hydrocarbon atmosphere reading must not exceed:

A. 0 % LEL
B. 1 % LEL
C. 10 % LEL
D. 50 % LEL

Answer: B — 1 % LEL

ISGOTT / enclosed space entry guidance: hydrocarbon vapour must not exceed 1% LEL before entry.

17. The three elements of the classic fire triangle are:

A. Fuel, air, water
B. Fuel, oxygen, heat (ignition)
C. Heat, smoke, light
D. Gas, flame, oxygen

Answer: B — Fuel, oxygen, heat (ignition)

Fire = fuel + oxygen + heat (ignition). Removing any one extinguishes the fire — the basis for the 4 extinguishing principles: cooling, smothering, starving, chemical chain-breaking.

18. The flash point of propane is approximately:

A. −42 °C
B. −60 °C
C. −104 °C
D. −188 °C

Answer: C — −104 °C

Propane flash point ≈ −104 °C (boiling point −42 °C). Since FP is far below ambient, any propane vapour is flammable if within its LEL–UEL.

19. The correct sequence of operating a portable fire extinguisher is:

A. Aim, Pull, Sweep, Squeeze
B. Pull, Aim, Squeeze, Sweep
C. Push, Aim, Squeeze, Stop
D. Pull, Activate, Spray, Stop

Answer: B — Pull, Aim, Squeeze, Sweep

PASS = Pull (the safety pin), Aim (at the base of the fire), Squeeze (the operating handle), Sweep (side to side).

20. Manual ESD activation push-buttons at the bunkering station must be located:

A. Inside the cargo control room only
B. At each bunker station, within easy reach of the operator
C. On the bridge only
D. Near the galley

Answer: B — At each bunker station, within easy reach of the operator

Manual ESD buttons are required both local (at each bunker station, within easy reach) and remote (CCR / bridge) so that the operator can initiate shutdown without delay.

21. The design philosophy of a Type-B independent tank is best described as:

A. Leak-free
B. Leak-before-failure
C. Fail-safe pressure vessel
D. Full secondary barrier

Answer: B — Leak-before-failure

Type-B (e.g. Moss spherical) uses detailed fatigue/crack-propagation analysis — any crack will be detected long before failure, so only a partial secondary barrier (drip tray) is needed.

22. When applying foam onto a flammable-liquid pool fire, the correct technique is to:

A. Direct the foam jet straight into the burning liquid
B. Aim onto an adjacent vertical surface or the back wall so the foam runs gently onto the liquid
C. Spray as a fine mist far above the fire
D. Allow water to mix with foam stream first

Answer: B — Aim onto an adjacent vertical surface or the back wall so the foam runs gently onto the liquid

Direct impact disturbs the foam blanket and splashes burning liquid. Aim onto a backstop or use a 'rain-down' technique so the foam settles gently and coalesces into an uninterrupted blanket.

23. For IGF ships, which technique is commonly used to demonstrate the functional safety of the fuel system?

A. FMEA / HAZID / HAZOP
B. Boiler efficiency test
C. Sea-trial alone
D. Noise survey

Answer: A — FMEA / HAZID / HAZOP

IGF Code requires formal risk-assessment studies — typically HAZID (hazard identification), HAZOP (hazard & operability) and FMEA (failure modes & effects analysis) — to prove safety equivalence.

24. The International Convention on Load Lines primarily establishes:

A. Maximum allowable cargo value
B. Minimum permissible freeboard for safe loading
C. Bunker fuel flash-point limits
D. Ship crew numbers

Answer: B — Minimum permissible freeboard for safe loading

ICLL (1966, as amended) sets minimum freeboard — the height between waterline and weather deck — to ensure reserve buoyancy and structural safety at each load condition.

25. An airlock between a safe and a hazardous space is usually maintained at:

A. Equal pressure to the hazardous space
B. Under-pressure relative to the safe space
C. Positive pressure with respect to the hazardous space
D. Vacuum

Answer: C — Positive pressure with respect to the hazardous space

Airlocks are over-pressurised relative to the hazardous space so that on door-opening air flows out into the hazardous area — preventing flammable vapour migrating to the safe side.

26. An IGF bunker-station fixed dry chemical system must deliver at a rate of not less than:

A. 1 kg/s for 30 s
B. 3.5 kg/s for 45 s
C. 5 kg/s for 60 s
D. 10 kg/s for 120 s

Answer: B — 3.5 kg/s for 45 s

IGF Code requires a fixed DCP system at each bunker station capable of at least 3.5 kg/s for 45 seconds to knock down a liquid-fuel jet fire during transfer.

27. The fine wire mesh fitted at the outlet of a cargo vent mast is primarily intended to:

A. Prevent rain ingress
B. Prevent flame propagation into the tank
C. Filter out odorants
D. Measure gas velocity

Answer: B — Prevent flame propagation into the tank

The flame screen (fine wire mesh) at a vent outlet acts as a flame arrester and stops flame passing back into the tank (SOLAS II-2/4.5).

28. In a 16-section Safety Data Sheet (SDS) prepared under GHS, First-Aid Measures are described in Section:

A. Section 2
B. Section 4
C. Section 8
D. Section 11

Answer: B — Section 4

Section 4 — First-aid Measures (routes of exposure: inhalation, skin, eye, ingestion; symptoms; medical attention). Section 2: hazards; 8: exposure controls/PPE; 11: toxicology.

29. The Upper Explosive Limit (UEL) of butane in air is approximately:

A. 1.8 %
B. 5 %
C. 8.4 %
D. 15 %

Answer: C — 8.4 %

Butane LEL ≈ 1.8 %, UEL ≈ 8.4 %. Concentrations above UEL are too rich to burn; below LEL too lean.

30. Liquid nitrogen boils at atmospheric pressure at approximately:

A. −42 °C
B. −104 °C
C. −162 °C
D. −196 °C

Answer: D — −196 °C

LN₂ boils at −195.8 °C (77 K). Used as inert gas / cryogen on board. Cold enough to embrittle ordinary carbon steel — special materials needed for piping.

Set 12 — 30 BIGF exit exam questions with answers

1. A fuel-tank valve that cannot be safely accessed locally is provided with:

A. A manual hand-wheel only
B. A remote-operating arrangement from the ECR / Cargo Control Station
C. A spring-loaded check only
D. A locked-shut blank flange

Answer: B — A remote-operating arrangement from the ECR / Cargo Control Station

IGF / IGC Code requires remote-operating arrangements (hydraulic, pneumatic or electric) for valves on fuel tanks where safe local access cannot be guaranteed.

2. Vapour pressure of a liquid is best defined as:

A. The pressure exerted by the liquid on the tank walls
B. The pressure of the vapour in equilibrium with its liquid at a given temperature
C. The atmospheric pressure at the boiling point
D. The pressure required to compress the vapour to liquid

Answer: B — The pressure of the vapour in equilibrium with its liquid at a given temperature

Vapour pressure rises with temperature; when it equals ambient pressure the liquid boils. It governs PRV sizing, holding time and tank reference temperature.

3. A Rapid Phase Transition (RPT) during LNG handling is the result of:

A. Static electricity ignition
B. Cryogenic LNG contacting water causing explosive boiling without combustion
C. Chemical reaction between LNG and oxygen
D. Metallurgical failure of piping

Answer: B — Cryogenic LNG contacting water causing explosive boiling without combustion

RPT is a physical (non-combustion) explosion from cryogenic LNG contacting a warmer liquid such as seawater — instantaneous flash vaporisation can produce significant overpressure.

4. Under STCW, a seafarer with direct responsibility for cargo and fuel operations on an IGF-fuelled ship must hold:

A. Only basic safety training
B. IGF Basic training certificate
C. IGF Advanced training certificate
D. Only a tanker endorsement

Answer: C — IGF Advanced training certificate

STCW Reg. V/3: Basic = those working on IGF-ships; Advanced = masters, engineers, officers and any person with immediate responsibility for fuel operations.

5. On hearing the general emergency alarm (seven short + one long), the first action of the crew is to:

A. Start firefighting
B. Proceed to their muster station with life-jacket and immersion suit
C. Launch the lifeboat immediately
D. Call the shore contact

Answer: B — Proceed to their muster station with life-jacket and immersion suit

General emergency signal: 7 short + 1 long blast. All crew proceed to muster stations with life-jacket, thermal protective aid / immersion suit, ready for further orders.

6. At standard atmospheric pressure and ambient temperature (20 °C), methane exists as:

A. Solid
B. Liquid
C. Gas
D. Supercritical fluid

Answer: C — Gas

Methane BP = −161.5 °C and critical Tc = −82.5 °C, so at any normal ambient temperature it is a gas. Liquefaction requires cryogenic cooling.

7. The atmospheric boiling point of vinyl chloride monomer (VCM) is approximately:

A. −14 °C
B. −42 °C
C. −104 °C
D. −162 °C

Answer: A — −14 °C

VCM boils at ≈ −13.8 °C (≈ −14 °C). It is shipped semi-refrigerated/pressurised. Critical Tc ≈ 156 °C, AIT ≈ 472 °C.

8. An IGF risk assessment shall consider hazards to:

A. Ship structure only
B. Personnel only
C. Personnel, environment and the ship
D. Cargo value only

Answer: C — Personnel, environment and the ship

IGF Code requires risk assessment covering personnel, ship and environment. Tools: HAZID, HAZOP, FMEA — outputs feed into the SMS and emergency plans.

9. Which agent is NOT generally suitable for a Class B (flammable liquid) fire?

A. AFFF foam
B. Dry chemical powder
C. CO₂
D. Water jet (straight stream)

Answer: D — Water jet (straight stream)

A straight water jet spreads burning liquid and can cause a boil-over. Atomised water mist, foam, DCP or CO₂ are suitable for Class B.

10. The secondary PRV on an IGF fuel tank typically lifts at what % above the MARVS / primary set pressure?

A. 5 %
B. 10 %
C. 15 %
D. 50 %

Answer: A — 5 %

Two independent PRVs are fitted: the second one is set ~5 % above the first, providing redundancy. Total combined relief capacity must handle fire-case boil-off.

11. The flash point of 1,3-butadiene is approximately:

A. −76 °C
B. −42 °C
C. +11 °C
D. +55 °C

Answer: A — −76 °C

1,3-butadiene FP ≈ −76 °C; boiling point −4 °C; LEL 2 %, UEL 12 %. Highly flammable gas used in rubber manufacture.

12. MARPOL Annex VI regulates ship-source:

A. Oil discharges
B. Noxious liquids
C. Sewage disposal
D. Air pollution (NOx, SOx, ODS, VOC, GHG)

Answer: D — Air pollution (NOx, SOx, ODS, VOC, GHG)

Annex VI covers air pollution — sulphur limits, NOx Tier I/II/III, ozone-depleting substances, VOCs, and the EEDI/CII carbon-intensity regime.

13. The fixed water-spray / deluge system on the cargo / fuel deck is provided primarily to:

A. Rinse salt deposits
B. Cool hull, manifold and vapour domes during a fire or LNG spill
C. Hydro-test the piping
D. Supply the fire main

Answer: B — Cool hull, manifold and vapour domes during a fire or LNG spill

Deluge keeps steel temperature above the brittle transition during a spill and cools surfaces during a fire. It does NOT spray directly on the LNG pool (splash / RPT risk).

14. The minimum capacity of a portable foam extinguisher provided in accommodation / service spaces is normally:

A. 2 litres
B. 9 litres
C. 20 litres
D. 45 litres

Answer: B — 9 litres

FSS Code: portable foam extinguishers in accommodation are typically 9 litres (≈ 9 kg) — equivalent fire-rating units of dry powder (5 kg) or CO₂ (5 kg) are also used.

15. Before use, an SCBA cylinder should be pressurised to at least:

A. 50 %
B. 70 %
C. 80 %
D. 90 %

Answer: D — 90 %

SCBA cylinders must be ≥ 90 % of rated pressure before use. Monthly checks and annual servicing are required (SOLAS II-2 / FSS Code).

16. On a gas-fuelled ship, ESD stands for:

A. Electrical Switching Device
B. Emergency Shut-Down
C. Engineer's Shutdown Door
D. Equipment Safety Disconnect

Answer: B — Emergency Shut-Down

ESD = Emergency Shut-Down: an automatic / manual system that closes valves, stops pumps and isolates fuel sources to make the ship safe in an emergency.

17. The recommended extinguishing technique for a pool fire of LNG on the deck is:

A. Direct sea-water jet
B. High-expansion foam (HiEx)
C. Straight water stream
D. Allow controlled burn while cooling surroundings

Answer: B — High-expansion foam (HiEx)

HiEx foam blankets the pool, cuts off air and reduces vaporisation. In some scenarios controlled burn-off while cooling surroundings with water spray is actually safer than extinguishing and leaving a huge gas cloud.

18. Which of the following is mandatory before starting hot work near a fuel system?

A. A permit to work and fire watch
B. Captain's verbal approval only
C. Weekly maintenance log entry
D. Union consent

Answer: A — A permit to work and fire watch

Hot work requires: PTW + risk assessment + atmospheric test < 1 % LEL + fire watch during work + 30 min continuous watch after completion + nearby extinguishing media.

19. In LNG bunkering, the ESD-2 (second-level emergency shutdown) causes:

A. Closure of the ESD valves only
B. Closure of ESD valves plus automatic disconnection (e.g. ERC release)
C. Shutdown of the main engine only
D. De-energising of the bunker station lighting

Answer: B — Closure of ESD valves plus automatic disconnection (e.g. ERC release)

ESD-1: stop the flow (close ESD valves both sides). ESD-2: automatic disconnection of the manifold (e.g. powered emergency release coupling — ERC) to prevent loss of containment if vessels drift.

20. A BLEVE most typically occurs when:

A. A tank is over-filled with inert gas
B. A liquefied-gas vessel is heated by external fire until catastrophic rupture
C. Two LNG parcels mix
D. Cryogenic liquid contacts warmer liquid

Answer: B — A liquefied-gas vessel is heated by external fire until catastrophic rupture

BLEVE = Boiling Liquid Expanding Vapour Explosion. Flame impingement weakens a pressurised vessel; rupture releases superheated liquid that flashes to vapour instantly, often followed by a fireball.

21. SOLAS III/19 requires an enclosed-space entry and rescue drill to be held at least:

A. Monthly
B. Every 2 months
C. Every 3 months
D. Annually

Answer: B — Every 2 months

SOLAS III/19.3.6: enclosed space entry and rescue drills shall take place at least once every two months.

22. At constant temperature, if the absolute pressure of a fixed mass of gas is doubled, its volume will:

A. Double
B. Remain the same
C. Halve
D. Quadruple

Answer: C — Halve

Boyle's Law: P × V = constant at constant T. Doubling P halves V.

23. Overall command of a shipboard firefighting operation at sea rests with the:

A. Chief Officer
B. Chief Engineer
C. Master
D. Safety Officer

Answer: C — Master

The Master has overall command; C/O typically leads the bridge/fire party, C/E the engine response. The Safety Officer coordinates, but authority rests with the Master.

24. A superheated vapour is best described as:

A. Liquid below its boiling point
B. A gas at temperature above its boiling point at the given pressure
C. Saturated mixture of liquid and vapour
D. A liquid pressurised above critical pressure

Answer: B — A gas at temperature above its boiling point at the given pressure

Superheated = single-phase gas heated above its saturation (boiling) temperature at the prevailing pressure. No liquid present; behaves like an ideal gas as superheat increases.

25. The primary purpose of bonding and grounding a bunker hose during LNG transfer is to:

A. Measure the flow rate
B. Prevent static electricity accumulation that could ignite vapour
C. Cool the hose
D. Monitor pressure

Answer: B — Prevent static electricity accumulation that could ignite vapour

Flowing cryogenic liquid/vapour can build static charge. Bonding the ship/shore manifolds and earthing them drains the charge safely and prevents an electrostatic discharge ignition.

26. On most cargo ships, fire drills must be held at least:

A. Weekly
B. Once a month
C. Every 3 months
D. Once a year

Answer: B — Once a month

SOLAS III/19.3.2 — each crew member shall participate in at least one abandon-ship drill and one fire drill every month.

27. Iso-butane is also known as:

A. iso-butane
B. methylpropane
C. both (a) and (b)
D. none of the above

Answer: C — both (a) and (b)

i-Butane (CH₃)₃CH = iso-butane (common) = 2-methylpropane (IUPAC). Both names are correct.

28. The low-pressure warning whistle on an SCBA set typically sounds when the cylinder pressure drops to:

A. 10 % of full charge
B. 25 % (~55 bar)
C. 50 %
D. 75 %

Answer: B — 25 % (~55 bar)

The whistle sounds at ~55 bar (≈ 25 % full charge), giving the wearer warning to evacuate to fresh air. Typical endurance thereafter is 4–6 minutes.

29. A crew member is found unconscious in a suspected H₂S atmosphere. You should:

A. Enter immediately without equipment
B. Start CPR at the casualty's location
C. Don SCBA, remove the casualty to fresh air then commence resuscitation
D. Wait for the doctor

Answer: C — Don SCBA, remove the casualty to fresh air then commence resuscitation

Never enter a toxic atmosphere without SCBA — you will become the next casualty. Remove the victim to fresh air, then begin resuscitation / call for medical assistance.

30. What is the typical minimum width of a cofferdam separating a fuel tank from accommodation?

A. 300 mm
B. 600 mm
C. 900 mm
D. 1500 mm

Answer: C — 900 mm

Cofferdams around fuel tanks are typically 900 mm minimum and A-60 insulated — providing thermal and fire separation between cryogenic fuel and safe spaces.

Set 13 — 30 BIGF exit exam questions with answers

1. Why is nitrogen considered a silent killer in enclosed spaces?

A. It is toxic and burns the lungs
B. It is odourless, colourless and displaces oxygen without warning
C. It ignites easily at body temperature
D. It reacts violently with moisture

Answer: B — It is odourless, colourless and displaces oxygen without warning

N₂ is non-toxic, non-reactive, non-odorised. Displacement of O₂ below ~10 % causes sudden collapse with no warning symptoms — most cryogenic-tank rescue fatalities involve N₂ asphyxiation.

2. What is meant by 'area classification' in explosion-prevention protection?

A. A method of analysing and classifying the areas where non-explosive gas atmospheres may occur
B. Ignoring the areas where explosive gas atmospheres may occur
C. A method of analysing and classifying the areas where explosive gas atmospheres may occur
D. None of the above

Answer: C — A method of analysing and classifying the areas where explosive gas atmospheres may occur

Area classification (IEC 60079-10) divides spaces into Zones 0/1/2 based on the likelihood of an explosive atmosphere — driving electrical equipment selection.

3. For continuous methane monitoring in an inerted atmosphere (no oxygen), the preferred detector type is:

A. Catalytic (pellistor)
B. Electrochemical
C. Non-dispersive infrared (NDIR)
D. Paper tape

Answer: C — Non-dispersive infrared (NDIR)

Pellistors need oxygen to oxidise the gas, so they fail in inert atmospheres. NDIR absorbs the hydrocarbon-specific IR band directly — works with or without O₂ and also gives % vol readings.

4. As per SOLAS Chapter III, abandon-ship drills for the crew shall be held:

A. Weekly
B. Monthly
C. Once every 3 months
D. Annually

Answer: B — Monthly

SOLAS III/19: abandon-ship and fire drills at monthly intervals; each crew member within 24 h of joining if they haven't participated in the last month.

5. MARPOL Annex II regulates:

A. Air pollution
B. Oil tankers only
C. Noxious Liquid Substances carried in bulk
D. Garbage management

Answer: C — Noxious Liquid Substances carried in bulk

Annex II covers NLS in bulk (chemical tankers) — categories X, Y, Z, OS — with discharge criteria and the Procedures & Arrangements (P&A) manual.

6. If a crew member's clothing catches fire on deck, the immediate correct action is to:

A. Run to the fire station to raise alarm
B. Remove clothing while walking
C. Stop, drop to the deck and roll to smother the flames
D. Jump overboard

Answer: C — Stop, drop to the deck and roll to smother the flames

Stop-Drop-Roll: stop (running fans flames), drop to the deck covering the face, and roll to smother. Then cool the burn with water and apply first-aid.

7. Which part of the IGF Code contains the prescriptive requirements for natural gas as fuel?

A. Part A — General
B. Part A-1 — Natural gas
C. Part B — Alternative design
D. Part D — Training

Answer: B — Part A-1 — Natural gas

Part A: general; Part A-1: specific prescriptive rules for natural gas as fuel; Part B: goal-based / alternative design for any low-flashpoint fuel; Part C/D/E cover SMS, training, etc.

8. Compared to air, LPG vapour is:

A. Lighter — rises and disperses quickly
B. Heavier — sinks and collects in low spaces
C. Equal density — stratifies slowly
D. Variable depending on temperature only

Answer: B — Heavier — sinks and collects in low spaces

Propane vapour density ≈ 1.5 × air; butane ≈ 2.0 × air. LPG vapour sinks into bilges, drains and low spaces — a major enclosed-space hazard.

9. Fuel gas pipes passing through accommodation / machinery spaces must be:

A. Single-wall with lagging
B. Double-walled or in a ventilated duct with gas detection
C. Buried in sand
D. Painted red

Answer: B — Double-walled or in a ventilated duct with gas detection

To prevent undetected leakage, gas piping in non-hazardous areas must be double-walled or in a mechanically ventilated gas-tight duct with gas detection.

10. MARPOL Annex I deals with prevention of pollution by:

A. Noxious liquid substances
B. Oil
C. Sewage
D. Garbage

Answer: B — Oil

Annex I: Oil. Annex II: noxious liquid substances in bulk. Annex III: harmful substances packaged. Annex IV: sewage. Annex V: garbage. Annex VI: air pollution.

11. Fuel hoses shall be designed for a bursting pressure:

A. less than 5 × the minimum pressure the hose can be subjected to during bunkering
B. less than 5 × the maximum pressure the hose can be subjected to during bunkering
C. not less than 5 × the maximum pressure the hose can be subjected to during bunkering
D. not less than 5 × the minimum pressure the hose can be subjected to during bunkering

Answer: C — not less than 5 × the maximum pressure the hose can be subjected to during bunkering

IGF Code: bursting pressure ≥ 5 × the maximum pressure the hose can be subjected to during bunkering, providing a substantial safety margin against hydraulic shock.

12. The flash point of methanol is approximately:

A. −42 °C
B. +11 °C
C. +38 °C
D. +60 °C

Answer: B — +11 °C

Methanol FP ≈ 11–12 °C, BP 64.7 °C — qualifies as 'low-flashpoint' under IGF (< 60 °C). Toxic (CNS effects) and burns with an almost invisible flame.

13. The typical low-alarm set point on a personal H₂S monitor is:

A. 1 ppm
B. 5 ppm
C. 10 ppm
D. 100 ppm

Answer: C — 10 ppm

Personal H₂S monitors commonly alarm at 10 ppm (TLV-TWA) low and 15 ppm (STEL) high. At 100 ppm IDLH — immediately dangerous to life and health.

14. Electrochemical cells in a portable multi-gas detector are most commonly used to measure:

A. Methane % LEL
B. Oxygen and toxic gases (CO, H₂S)
C. Hydrocarbon % volume
D. Radiation

Answer: B — Oxygen and toxic gases (CO, H₂S)

Electrochemical cells give an output current proportional to gas concentration; used for O₂, CO, H₂S, SO₂, NH₃, Cl₂. Typical lifespan 2–3 years.

15. The minimum service duration of an Emergency Escape Breathing Device (EEBD) on a ship is:

A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 30 minutes

Answer: B — 10 minutes

FSS Code Ch.3 2.2: an EEBD shall have a service duration of at least 10 minutes.

16. Which is the most suitable portable extinguisher for a paper / wood fire?

A. Water or AFFF foam
B. CO₂
C. BC dry chemical powder only
D. Wet chemical Class F

Answer: A — Water or AFFF foam

Class A (paper / wood) needs cooling + soaking — water or foam. CO₂ and BC powder don't cool deeply, so the fire can re-ignite. ABC powder also works but water/foam remains the preferred answer.

17. LEL stands for:

A. Lower Explosive Limit
B. Liquid Evaporation Level
C. Local Exposure Limit
D. Low Energy Line

Answer: A — Lower Explosive Limit

LEL = Lower Explosive Limit (also Lower Flammable Limit, LFL) — the minimum vapour concentration in air that will ignite. Below LEL the mixture is too lean to burn.

18. The flammable range of hydrogen in air is approximately:

A. 2 – 9 %
B. 4 – 75 %
C. 5 – 15 %
D. 15 – 28 %

Answer: B — 4 – 75 %

Hydrogen has an extremely wide flammable range 4–75 % with very low ignition energy (~0.02 mJ), making leak control critical on H₂-fuelled vessels.

19. Electrical equipment housed in an 'Ex-d' (flameproof) enclosure is designed to:

A. Prevent any gas from entering the enclosure
B. Contain an internal explosion and cool the escaping gas below ignition temperature
C. Operate only in non-hazardous areas
D. Run at intrinsically safe energy levels

Answer: B — Contain an internal explosion and cool the escaping gas below ignition temperature

Ex-d allows gas ingress but contains an internal ignition; flame paths cool the escaping gases below the surrounding atmosphere's ignition temperature so the external mixture does not ignite.

20. The approximate percentage of oxygen (by volume) in normal atmospheric air is:

A. 16 %
B. 20.9 %
C. 25 %
D. 78 %

Answer: B — 20.9 %

Normal air ≈ 20.9 % O₂, 78 % N₂, 1 % others. Enclosed-space acceptable range 19.5–23.5 %; < 19.5 % O₂-deficient, > 23.5 % O₂-enriched (fire hazard).

21. A fuel vent outlet must be located at least how far from air intakes and exhaust outlets?

A. 3 m
B. 5 m
C. 10 m
D. 25 m

Answer: C — 10 m

Vent discharges must be ≥ 10 m from air intakes, exhaust outlets, openings to accommodation and similar openings, to avoid ingress of flammable vapour.

22. Since 1 January 2020, the global MARPOL Annex VI limit on sulphur content of fuel oil used outside ECAs is:

A. 0.10 % m/m
B. 0.50 % m/m
C. 1.50 % m/m
D. 3.50 % m/m

Answer: B — 0.50 % m/m

Global sulphur cap 0.50 % m/m since 2020-01-01 (was 3.5 %). Inside SECAs it is 0.10 %. LNG fuel inherently meets these limits.

23. A 'Hazardous Zone 0' on an IGF fuelled ship is a space where a flammable atmosphere:

A. Is never expected
B. Is present continuously or for long periods in normal operation
C. May occur occasionally in normal operation
D. Exists only under abnormal conditions

Answer: B — Is present continuously or for long periods in normal operation

Zone 0 = flammable gas present continuously / for long periods during normal operation (e.g. inside fuel tanks, vent piping). Zone 1 = likely in normal op; Zone 2 = only abnormal.

24. During bunkering, which event will NOT automatically trigger an ESD?

A. Excess liquid level (≥ 98 %)
B. Low fuel supply pressure / high pressure trip
C. Gas detection 40–60 % LEL in the bunkering area
D. Routine shift handover

Answer: D — Routine shift handover

Auto-ESD triggers: high level, high/low pressure, high temperature, gas/fire detection, loss of ventilation, manual push-button. Routine admin events do not trigger ESD.

25. The 'reference temperature' for an IGF fuel tank is:

A. The ambient sea temperature
B. The temperature at which vapour pressure equals the PRV set pressure
C. The minimum design temperature
D. The temperature at the tank bottom

Answer: B — The temperature at which vapour pressure equals the PRV set pressure

Reference temperature = the temperature of the cargo at which its vapour pressure corresponds to the PRV set pressure. Maximum permissible filling limit is calculated at this temperature.

26. A 'jet fire' from an LNG pipework leak is best controlled by:

A. Spraying water directly into the jet
B. Isolating the fuel supply and cooling adjacent structure with water spray
C. Flooding the compartment with CO₂ immediately
D. Adding foam

Answer: B — Isolating the fuel supply and cooling adjacent structure with water spray

Primary action: cut off the fuel at source. Secondary: cool surrounding structure to prevent BLEVE / brittle fracture. Extinguishing the jet before isolation allows an unburnt cloud to form and flash back.

27. A photo-electric (optical) smoke detector responds best to:

A. Fast-flaming fires with little smoke
B. Smouldering fires producing visible smoke
C. Pure heat without smoke
D. Toxic gas concentrations

Answer: B — Smouldering fires producing visible smoke

Photo-electric detectors sense light scattered by smoke particles — most responsive to large/visible smoke from smouldering fires. Ionisation detectors respond faster to fast-flaming combustion.

28. Span gas calibration of a gas detector adjusts the:

A. Sensor's high-concentration reading to match the known gas value
B. Zero reading in clean air
C. Alarm set point only
D. Battery level

Answer: A — Sensor's high-concentration reading to match the known gas value

Zero calibration sets the baseline in clean air; span calibration adjusts the upper scale with a known reference gas (e.g. 50 % LEL methane) to the correct reading.

29. Which of the following is NOT a required pre-bunkering check on an LNG-fuelled ship?

A. ESD system test
B. Gas-detection system test
C. Ship-shore connection / bonding
D. Main engine performance trial

Answer: D — Main engine performance trial

Pre-bunker checks cover ESD, gas/fire detection, firefighting readiness, ship-shore communications and bonding. Main-engine performance trials are unrelated to bunkering.

30. R-22 refrigerant is chemically known as:

A. Chlorodifluoromethane (CHClF₂)
B. Dichlorodifluoromethane (CCl₂F₂)
C. Tetrafluoroethane
D. Ammonia

Answer: A — Chlorodifluoromethane (CHClF₂)

R-22 = chlorodifluoromethane, CHClF₂, an HCFC. Being phased out under the Montreal Protocol due to ozone-depletion potential (ODP ≈ 0.055). MARPOL Annex VI Reg. 12 controls ODS on ships.

Set 14 — 39 BIGF exit exam questions with answers

1. The typical discharge time of a 5 kg portable DCP extinguisher at full flow is approximately:

A. 5 – 10 seconds
B. 15 – 25 seconds
C. 45 – 60 seconds
D. 3 – 5 minutes

Answer: B — 15 – 25 seconds

A 5 kg DCP unit discharges fully in roughly 15–25 s (9 kg ≈ 25–30 s). This is why aim and technique matter — the agent is gone very quickly.

2. The critical pressure of a gas is:

A. Its maximum allowable working pressure
B. The pressure required to liquefy the gas at its critical temperature
C. The PRV set pressure
D. Atmospheric pressure at sea level

Answer: B — The pressure required to liquefy the gas at its critical temperature

At the critical temperature the gas and liquid phases become indistinguishable; the critical pressure is the minimum pressure needed to liquefy the gas at that temperature.

3. The liquefied-gas fuel cooling/holding method shall maintain tank pressure below the set pressure for at least:

A. 30 days
B. 15 days
C. 25 days
D. 48 days

Answer: B — 15 days

IGF Code Pt. A-1: minimum holding time of 15 days at maximum design ambient with the tank initially full at normal service pressure.

4. Why is a cascade (mixed-refrigerant) cycle used in LNG reliquefaction plants instead of a single-stage cycle?

A. It is cheaper
B. Single-stage refrigeration cannot reach the very low evaporation temperatures (≈ −160 °C) efficiently
C. It avoids the use of compressors
D. It eliminates the need for heat exchangers

Answer: B — Single-stage refrigeration cannot reach the very low evaporation temperatures (≈ −160 °C) efficiently

A cascade uses successive refrigerants (e.g. propane → ethylene → methane / mixed refrigerant) to step down to LNG temperatures. A single refrigerant cannot span the huge temperature gradient efficiently.

5. The critical temperature of methane is approximately:

A. −42 °C
B. −82.5 °C
C. −162 °C
D. −196 °C

Answer: B — −82.5 °C

Methane Tc ≈ −82.5 °C (190.6 K), Pc ≈ 46 bar. Above Tc methane cannot be liquefied no matter how high the pressure.

6. In an inert atmosphere, the only permitted type of tank level gauging is:

A. Open gauging
B. Restricted gauging
C. Closed gauging
D. Manual sounding rod

Answer: C — Closed gauging

Closed gauging (sealed float/radar/pressure) has no opening to atmosphere and is mandatory for toxic / flammable / inerted tanks. Restricted uses a small port; open is only for non-hazardous cargoes.

7. Occupational Exposure Limits (TLV-TWA, STEL) and recommended PPE are given in SDS Section:

A. Section 4
B. Section 8
C. Section 10
D. Section 15

Answer: B — Section 8

Section 8 — Exposure Controls / Personal Protection: contains OELs (TLV-TWA 8 h, STEL 15 min, Ceiling) and the PPE (gloves, goggles, respirator) required.

8. To prevent brittle fracture of the ship's steel during an LNG spill on deck, what is provided?

A. Direct seawater jet onto the spill
B. Stainless-steel drip trays and a deck water-spray curtain
C. Chemical foam blanket
D. Nitrogen flooding of the deck

Answer: B — Stainless-steel drip trays and a deck water-spray curtain

Spills are directed to stainless drip trays; a water-spray curtain keeps hull steel above its ductile-brittle transition. NEVER spray water directly on liquid LNG (rapid-phase-transition / splashing).

9. Gas hydrates in LNG cargo systems are controlled by:

A. Injecting methanol / maintaining low dew-point inert gas
B. Adding oxygen to the tank
C. Heating the liquid above boiling point
D. Raising the tank pressure

Answer: A — Injecting methanol / maintaining low dew-point inert gas

Hydrates (ice-like water + HC crystals) block valves and instruments. Control: dry inert gas (dew point ≤ −45 °C), methanol/glycol inhibitors, good dryness of piping before use.

10. The IGF Code is made mandatory through which SOLAS chapter / part?

A. SOLAS II-2 Part C
B. SOLAS II-1 Part G
C. SOLAS V Chapter 4
D. SOLAS III Part B

Answer: B — SOLAS II-1 Part G

SOLAS Chapter II-1, Part G (Regulations 55–57) makes the IGF Code mandatory for ships ≥ 500 GT built on/after 1 Jan 2017 using low-flashpoint fuels.

11. A fuel-gas supply / compressor room must have mechanical ventilation of at least:

A. 6 air changes/hour
B. 10 air changes/hour
C. 30 air changes/hour
D. 100 air changes/hour

Answer: C — 30 air changes/hour

IGF Code requires a minimum 30 air changes per hour (mechanical, negative-pressure) in the gas fuel preparation / compressor room, with redundancy and gas-detection interlocks.

12. STEL stands for:

A. Short-Term Exposure Limit
B. Standard Threshold Exposure Level
C. Safety Trigger Emergency Limit
D. Special Toxicity Exposure Line

Answer: A — Short-Term Exposure Limit

STEL = Short-Term Exposure Limit — 15-minute time-weighted average concentration that should not be exceeded at any time during the workday (ACGIH definition).

13. The role of a Recognised Organisation (Class Society — IACS member) under the IGF framework is to:

A. Employ the seafarers
B. Approve design, survey construction and certify the ship on behalf of the Flag State
C. Operate the bunker terminal
D. Set fuel prices

Answer: B — Approve design, survey construction and certify the ship on behalf of the Flag State

Flag States typically delegate statutory design approval, construction survey and periodic certification to Recognised Organisations (usually IACS class societies).

14. Solid CO₂ (dry ice) sublimes at atmospheric pressure at approximately:

A. 0 °C
B. −33 °C
C. −78.5 °C
D. −162 °C

Answer: C — −78.5 °C

Solid CO₂ sublimes directly to vapour at −78.5 °C at 1 atm. This produces the cooling and vapour blanket seen at a discharging CO₂ extinguisher or dry-ice blasting.

15. IMO stands for:

A. International Marine Operators
B. Indian Maritime Office
C. International Maritime Organization
D. Inter-Ministerial Office

Answer: C — International Maritime Organization

IMO = International Maritime Organization — UN specialised agency, headquartered in London, responsible for SOLAS, MARPOL, STCW and the IGF Code.

16. Which secondary barrier is required for a Type-A independent tank?

A. No secondary barrier
B. Partial secondary barrier
C. Full secondary barrier
D. Integrated membrane

Answer: C — Full secondary barrier

Type-A tanks use prismatic low-pressure design and are NOT crack-arresting, so a FULL secondary barrier (inert hold) is mandatory to contain any leaked cryogenic liquid.

17. Immediate first aid for a thermal burn is to:

A. Apply butter or oil
B. Cool the area with running water for at least 10 minutes
C. Break any blisters that form
D. Wrap tightly in cotton wool

Answer: B — Cool the area with running water for at least 10 minutes

Cool the burn under running water (not ice) for at least 10 minutes — limits tissue damage. Never apply creams/butter/oil; never break blisters. Cover loosely with a non-adherent sterile dressing and seek medical help.

18. Which portable extinguisher causes extreme frost on the discharge horn after use?

A. Water
B. AFFF foam
C. CO₂
D. Dry chemical powder (BC)

Answer: C — CO₂

CO₂ is stored as high-pressure liquid; rapid expansion through the horn causes Joule-Thomson cooling to ≈ −78 °C, producing frost. Never hold the horn — cold-burn risk.

19. The minimum acceptable oxygen level for routine enclosed-space entry is:

A. 16 %
B. 17 %
C. 19.5 %
D. 23.5 %

Answer: C — 19.5 %

Most administrations and IACS Rec. 72 require O₂ ≥ 19.5 % for entry. Below this a self-contained breathing apparatus (SCBA) is mandatory.

20. First aid for LNG cold-burn (frostbite) of the skin is to:

A. Rub the area briskly to restore circulation
B. Immerse in hot water (50 °C+)
C. Flush gently with lukewarm (40–42 °C) water and seek medical help
D. Apply ice packs

Answer: C — Flush gently with lukewarm (40–42 °C) water and seek medical help

Rewarm frozen tissue gradually in 40–42 °C water. Never rub (tissue damage) and never use hot water (causes additional thermal burns over the frost-damaged skin).

21. Which SDS section provides the boiling point, vapour pressure, density and flash point of a substance?

A. Section 2 — Hazards
B. Section 9 — Physical & Chemical Properties
C. Section 13 — Disposal
D. Section 14 — Transport

Answer: B — Section 9 — Physical & Chemical Properties

Section 9 of the GHS SDS contains the physical / chemical properties used during onboard operations — boiling point, flash point, vapour pressure, specific gravity, solubility, etc.

22. The molecular formula of ethylene is:

A. CH₄
B. NH₃
C. C₂H₄
D. O₂

Answer: C — C₂H₄

Ethylene = C₂H₄ (alkene, double bond). Methane = CH₄, ammonia = NH₃, oxygen = O₂.

23. 'Intrinsically safe' electrical equipment in a gas-hazardous area is designed so that:

A. It cannot catch fire
B. Any spark/heat it releases is below the minimum ignition energy of the gas/air mixture
C. It has no moving parts
D. It works only under water

Answer: B — Any spark/heat it releases is below the minimum ignition energy of the gas/air mixture

Ex-i equipment limits the available electrical energy (voltage × current × time) to below the minimum ignition energy of the specified gas group, so even a fault cannot ignite the atmosphere.

24. During adult cardiopulmonary resuscitation (CPR), the recommended chest-compression depth is approximately:

A. 1 – 2 cm
B. 2 – 3 cm
C. 5 – 6 cm
D. 8 – 10 cm

Answer: C — 5 – 6 cm

Current resuscitation guidelines: compress the adult chest 5–6 cm at a rate of 100–120 per minute, allowing full recoil, with minimum interruptions.

25. A catalytic (pellistor) combustible-gas sensor operates by:

A. Absorbing light at a specific wavelength
B. Oxidising the gas on a heated bead and measuring the resistance change
C. Measuring ionisation current
D. Detecting refractive index change

Answer: B — Oxidising the gas on a heated bead and measuring the resistance change

Pellistor = two matched beads (active catalytic + reference). The active bead oxidises the gas, heats up, its resistance rises — output proportional to % LEL. Requires O₂ to work; poisoned by silicones/lead.

26. A fire involving paper, wood and textiles is classified as:

A. Class A
B. Class B
C. Class C
D. Class D

Answer: A — Class A

Class A = solid combustibles (wood, paper, textiles); B = flammable liquids; C = flammable gases (EU) / electrical (US); D = metals; F/K = cooking oil.

27. In LNG storage, 'rollover' refers to:

A. Ship motion causing sloshing damage
B. Sudden mixing of stratified layers releasing a large vapour burst
C. Overfilling of the cargo tank
D. Reversal of cargo pumps

Answer: B — Sudden mixing of stratified layers releasing a large vapour burst

When two LNG parcels of different density are loaded without mixing, they stratify. Weathering eventually inverts the density and the layers 'roll over' — releasing a large vapour volume that can overwhelm PRVs.

28. MARPOL Annex IV deals with the prevention of pollution from ships by:

A. Oil
B. Sewage
C. Garbage
D. Air emissions

Answer: B — Sewage

Annex IV: sewage — holding tanks, approved treatment plant and discharge distances from nearest land.

29. A 'bump test' on a portable gas detector means:

A. Dropping it to verify mechanical toughness
B. A brief exposure to a known span gas to verify sensor response and alarms
C. Sending it to a lab for calibration
D. Resetting to zero in fresh air

Answer: B — A brief exposure to a known span gas to verify sensor response and alarms

A bump test applies a known gas concentration for a few seconds to confirm the sensor and alarm respond. It is NOT a full calibration — just a daily functional check.

30. An EEBD must NOT be used for:

A. Escape from accommodation
B. Escape from engine room
C. Entry to a smoke-filled or toxic space for firefighting / rescue
D. Training drills

Answer: C — Entry to a smoke-filled or toxic space for firefighting / rescue

EEBDs are single-use escape devices — they must never be used for firefighting or casualty rescue. Only full SCBA is acceptable for entry.

31. Saturated vapour pressure of a liquid increases when:

A. Temperature decreases
B. Temperature increases
C. Pressure decreases at constant temperature
D. Volume is reduced at constant temperature

Answer: B — Temperature increases

SVP rises with temperature — this is why boil-off accelerates in hot ambient and why PRV sizing must consider fire-exposure heating.

32. The two automatic isolating valves required in series on the gas-fuel supply pipe entering each consumer are:

A. Two manual gate valves
B. Master gas valve + Double-block-and-bleed shut-down valves (SDVs)
C. Two non-return check valves
D. One PRV + one PSV

Answer: B — Master gas valve + Double-block-and-bleed shut-down valves (SDVs)

IGF Code: each consumer is protected by a master gas valve and a 'double-block-and-bleed' arrangement (two automatic SDVs with a vent between) so a single failure cannot allow gas to leak to the consumer.

33. On an IGF ship, the fresh-water spray / deluge system isolation valves should normally be:

A. Manually operated only
B. Automatically operated with manual back-up
C. Automatic only, no manual option
D. Sealed shut

Answer: B — Automatically operated with manual back-up

The fresh-water fire/deluge system valves are remotely/automatically operable (e.g. on gas-detection trip) with manual back-up, so protection initiates without waiting for crew response.

34. The auto-ignition temperature of vinyl chloride monomer (VCM) is approximately:

A. 350 °C
B. 472 °C
C. 537 °C
D. 650 °C

Answer: B — 472 °C

Auto-ignition temperature of VCM ≈ 472 °C — the lowest temperature at which vapour self-ignites in air without an external ignition source.

35. The maximum liquid filling limit for a Type-C fuel tank is normally restricted to (volume %):

A. 78 %
B. 85 %
C. 95 %
D. 98 %

Answer: C — 95 %

IGF limits filling so that at the reference temperature the liquid does not exceed 98 % of tank volume, but the operational maximum is typically set at 95 % to allow for density/temperature variations.

36. What is the minimum height of a fuel vent mast outlet above the weather deck (B = ship breadth)?

A. B/4 or 4 m, whichever greater
B. B/3 or 6 m, whichever greater
C. B/2 or 10 m, whichever greater
D. Always 10 m fixed

Answer: B — B/3 or 6 m, whichever greater

IGF Code: vent outlet must discharge at B/3 or 6 m above the weather deck (whichever is greater) and at least 6 m above walkways, 10 m from air intakes.

37. Which of the following best describes ammonia (NH₃) as a marine fuel hazard?

A. Highly flammable, narrow range 2–8 %
B. Toxic + corrosive, narrow flammable range ~15–28 %
C. Non-toxic inert gas
D. Spontaneously combustible in air

Answer: B — Toxic + corrosive, narrow flammable range ~15–28 %

Ammonia is primarily a toxic / corrosive hazard (IDLH 300 ppm) with a relatively narrow flammable range 15–28 %. Toxicity is the controlling design criterion.

38. The flammable range of methane in air is approximately:

A. 2 – 9 %
B. 5 – 15 %
C. 4 – 75 %
D. 1.8 – 8.4 %

Answer: B — 5 – 15 %

Methane: LEL ≈ 5 %, UEL ≈ 15 % by volume. Below 5 % too lean; above 15 % too rich. (Hydrogen 4–75 %; butane 1.8–8.4 %.)

39. The connections at the LNG bunkering manifold shall be of __________ type, equipped with additional safety dry break-away coupling / self-sealing quick release.

A. wet-disconnect
B. dry-disconnect
C. dry-connect
D. wet-connect

Answer: B — dry-disconnect

IGF Code requires dry-disconnect couplings (no leakage on disconnect) plus a dry break-away or quick-release fitting that protects the manifold if the ship drifts.

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

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