AIGF exit exam questions and answers — Set 4 — Advanced Training for Ships subject to the IGF Code
Set 4 of the Advanced Training for Ships subject to the IGF Code (AIGF) exit exam bank — 30 of 468 questions, with the correct option marked and a one-line explanation for every one. Read it end to end, jump to a single set, or search it — then sit the same bank as a timed paper. The real DG Shipping exit exam is 30 marks with 15 to pass.
These are the bank's original groupings. Practising deals the whole bank out again every time you reshuffle, so a practice “Set 3” is a different 30 questions each time — the set numbers below are the source file's, and are only used here so the key stays navigable. Options are listed in their original order with fixed letters; when you practise, those move too.
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Set 4 — 30 AIGF exit exam questions with answers
1. In Liquefied Petroleum Gas, __________ can be shipped seperately or as a mixture.
- A. both (a) and (b)
- B. none of the above
- C. propane
- D. butane
Answer: A — both (a) and (b)
Both propane and butane are LPG products that can be shipped separately or as a mixture, so the blank is completed by both.
2. Liquefied Petroleum Gas may be
- A. refinery by-products
- B. All of the above
- C. may be produced in conjunction with natural gas
- D. may be produced in conjunction with crude oil
Answer: B — All of the above
LPG may be produced as a refinery by-product, or recovered in conjunction with natural gas production and crude oil production, so all the listed sources apply.
3. MARVS means
- A. Minimum Allowable Relief Valve Setting
- B. Maximum Allowable Relief Valve Setting
- C. Maximum Allowed Regional Valve Setting
- D. Minimum Allotted Relief Valve Setting
Answer: B — Maximum Allowable Relief Valve Setting
MARVS means Maximum Allowable Relief Valve Setting of a fuel or cargo tank. This is the highest pressure at which the tank's pressure relief valves may be set, as defined in the IGC and IGF Codes, and it is a basis of the tank's design.
4. Maximum Allowable Relief Valve Setting on a ship's cargo tank as stated on the __________
- A. refinery by-products
- B. ship's Certificate of Fitness
- C. free from chemical
- D. production of conjunction with crude oil
Answer: B — ship's Certificate of Fitness
Under the IGC Code the MARVS of each cargo tank is stated on the ship's International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk.
5. What is MLC?
- A. Multi Liquid Column
- B. Meters Liquid Column
- C. Meters Limit Column
- D. Multi Limit Column
Answer: B — Meters Liquid Column
MLC stands for metres liquid column, a measure of pressure expressed as the height (head) of a column of liquid. It is used for pump heads in cargo pumping.
6. Meters Liquid Column is a unit of ________ used in some cargo pumping operations.
- A. volume
- B. pressure
- C. none of the above
- D. mass
Answer: B — pressure
Metres liquid column expresses pressure as the head of a column of the pumped liquid, which is why it is used for cargo pump delivery head.
7. What is Mollier diagram?
- A. graphic method of representing ship route
- B. graphic method of representing heat quantities of a refrigerant
- C. graphic method of representing ship design
- D. All of the above
Answer: B — graphic method of representing heat quantities of a refrigerant
A Mollier (pressure-enthalpy) diagram is a graphic method of representing the heat quantities (enthalpy) of a refrigerant or liquefied gas and its condition at different temperatures and pressures. It is used to analyse reliquefaction cycles.
8. In Mollier diagram, graphic method of representing heat quantities and the conditions of liquefied gas at different ____________
- A. density
- B. volume
- C. pressure
- D. temperature
Answer: D — temperature
The Mollier diagram shows the heat content and state (liquid, vapour, mixture) of a liquefied gas at different temperatures and pressures, so temperature completes the statement.
9. What re the gases associated with Natural Gas Liquid?
- A. Butane
- B. All of the above
- C. Ethane
- D. Propane
Answer: B — All of the above
Natural gas liquids are the heavier hydrocarbons separated from natural gas, mainly ethane, propane and butane (plus pentanes), so all the listed gases apply.
10. What is oxygen analyser?
- A. Instrument used to measure propane concentrations in percentage by volume
- B. Instrument used to measure ethane concentrations in percentage by volume
- C. Instrument used to measure oxygen concentrations in percentage by volume
- D. Instrument used to measure butane concentrations in percentage by volume
Answer: C — Instrument used to measure oxygen concentrations in percentage by volume
An oxygen analyser is an instrument that measures oxygen concentration as a percentage by volume. It is used to check inerting and to confirm a safe atmosphere (21% O2) before entry.
11. In oxygen analyser which gas in measured?
- A. Propane
- B. oxygen
- C. Pentane
- D. Butane
Answer: B — oxygen
Oxygen analyzers measure oxygen volumetric concentration (0-21% O2) in enclosed spaces to verify breathable conditions or inerting completeness.
12. What is oxygen deficient atmosphere?
- A. atmosphere containing less than 11 percent oxygen by volume
- B. atmosphere containing less than 21 percent oxygen by volume
- C. atmosphere containing less than 11 percent oxygen by pressure
- D. atmosphere containing less than 21 percent oxygen by pressure
Answer: B — atmosphere containing less than 21 percent oxygen by volume
An oxygen-deficient atmosphere is one containing less than the normal 21% oxygen by volume. Spaces should read 21% O2 before entry without breathing apparatus.
13. How is peroxide formed?
- A. none of the above
- B. chemical combination of cargo liquid with atmosphere oxygen
- C. both (a) and (b)
- D. chemical combination of vapour with atmosphere oxygen
Answer: C — both (a) and (b)
Peroxides are formed by the slow autoxidation of unsaturated chemical gas monomers (like 1,3-butadiene or isoprene) when exposed to atmospheric oxygen.
14. Chemical combination of cargo liquid with oxygen from other source and vapour with oxygen from other source forms __________
- A. Formation of Peroxide
- B. Formation of Oxygen
- C. Formation of oxide
- D. Formation of Ethane
Answer: A — Formation of Peroxide
Contact between reactive chemical monomers and atmospheric oxygen results in the formation of hazardous, unstable peroxides.
15. Qualities for Peroxide is
- A. none of the above
- B. highly reactive
- C. both (a) and (b)
- D. potential hazard
Answer: C — both (a) and (b)
Peroxides are highly reactive substances that can decompose violently, give off oxygen and support or start combustion. They are therefore both highly reactive and a potential hazard, and need careful segregation, temperature control and inhibitors where required.
16. In some cases, Peroxide is
- A. unstable
- B. both (a) and (b)
- C. none of the above
- D. potential hazard
Answer: B — both (a) and (b)
Certain peroxides are powerful chemical oxidizing agents capable of causing spontaneous decomposition and violent explosions.
17. How is polymer formed?
- A. The chemical union of two or more molecules of the same compound to form a larger molecule of a new compound
- B. The chemical union of two or more molecules of the same compound to form a smaller molecule of a new compound
- C. The chemical reaction of one molecule of the same compound to form a smaller molecule of a new compound
- D. The chemical reaction of one molecule of the same compound to form a larger molecule of a new compound
Answer: A — The chemical union of two or more molecules of the same compound to form a larger molecule of a new compound
Polymerization is a chemical reaction in which monomer molecules combine together to form large repeating polymer chains, releasing substantial exothermic heat.
18. What is the process for the chemical union of two or more molecules of the same compound to form a larger molecule of a new compound called?
- A. Vaporization
- B. Gas freeing
- C. Static electricity
- D. Polymerisation
Answer: D — Polymerisation
Polymerization is the chemical reaction where monomer units bond together, which if uncontrolled on ships can generate dangerous temperatures and pressures.
19. What is a Primary Barrier in liquified gas tanks?
- A. seperating barrier between liquid and gas
- B. Inner surface designed to contain the cargo when the cargo containment system includes a secondary barrier
- C. nothing special barrier
- D. chemical combination of cargo liquid with oxygen from other source
Answer: B — Inner surface designed to contain the cargo when the cargo containment system includes a secondary barrier
The primary barrier is the inner liquid-tight containment boundary designed to directly hold cryogenic cargo or fuel under normal operating conditions.
20. ___________ is a refrigerant gas?
- A. B65
- B. R22
- C. C24
- D. A22
Answer: B — R22
R22 (chlorodifluoromethane / HCFC-22) is a synthetic halogenated hydrocarbon gas historically used as an industrial refrigerant.
21. What is the full chemical name of R22?
- A. monochloro difluoromethane
- B. monoflouride difluoromethane
- C. monochloride dimethane
- D. monochloro dimethane
Answer: A — monochloro difluoromethane
R22 is chlorodifluoromethane (CHClF2), often called monochlorodifluoromethane. It is an HCFC refrigerant that is being phased out under the Montreal Protocol and MARPOL Annex VI because it depletes the ozone layer.
22. What are the characteristics of R22?
- A. All of the above
- B. colourless
- C. non-flammable
- D. odourless
Answer: A — All of the above
R22 is a non-flammable, colorless, faint-ether-odor gas with a boiling point of -40.8°C at atmospheric pressure.
23. R22 is virtually non-toxic with a _______
- A. TLV of 1,000 ppm
- B. TLV of 2 ppm
- C. TLV of 500 ppm
- D. TLV of 30 ppm
Answer: A — TLV of 1,000 ppm
R22 has a low acute toxicity profile with a standard Threshold Limit Value - Time Weighted Average (TLV-TWA) of 1,000 ppm.
24. What is relative liquid density?
- A. The chemical union of two or more molecules of the same compound to form a larger molecule of a new compound
- B. The mass of the gas at a given temperature compared with the mass of an equal volume of gas at the same temperature at a different given temperature
- C. The mass of a liquid at a given temperature compared with the mass of an equal volume of fresh water at the same temperature at a different given temperature
- D. Inner surface designed to contain the cargo when the cargo containment system includes a secondary barrier
Answer: C — The mass of a liquid at a given temperature compared with the mass of an equal volume of fresh water at the same temperature at a different given temperature
Relative liquid density is the dimensionless ratio of the mass of a liquid volume to the mass of an equal volume of pure fresh water at reference temperature.
25. What is relative vapour density?
- A. Inner surface designed to contain the cargo when the cargo containment system includes a secondary barrier
- B. The chemical union of two or more molecules of the same compound to form a larger molecule of a new compound
- C. The mass of a liquid at a given temperature compared with the mass of an equal volume of fresh water at the same temperature at a different given temperature
- D. The mass of a vapour compared with the mass of an equal volume of air, both at standard condition of temperature and pressure
Answer: D — The mass of a vapour compared with the mass of an equal volume of air, both at standard condition of temperature and pressure
Relative vapor density is the ratio of the mass of a gas volume to the mass of an equal volume of dry air at standard temperature and pressure (Air = 1.0).
26. What is restricted gauging?
- A. none of the above
- B. system employing a device, which penetrates the tank and which when in use permits a small quantity of cargo vapour to be expelled to the atmosphere.
- C. the device is kept completely closed when the device is not in use
- D. both (a) and (b)
Answer: D — both (a) and (b)
Restricted gauging uses an ullage device designed to limit the release of vapor during level measurement, such as sounding tubes with shut-off balls.
27. In restricted gauging, when the device is not in use
- A. the device is kept open
- B. none of the above
- C. the device is kept operated
- D. the device is kept completely closed
Answer: D — the device is kept completely closed
In restricted gauging arrangements, the measurement orifice is kept tightly closed when not in active use to prevent flammable vapor escape.
28. What is roll over?
- A. The pressure at which a vapour is in equilibrium with its liquid at a specific temperature
- B. The phenomenon where the stabilty of two stratified layers of liquid of differing relative density distributed resulting in a spomtaneous rapid mixing of the layers accompanied in the case of liquefied gases, by violent vapour evolution
- C. Heat energy given to or taken from a substance which raises or lowers its temperature
- D. The mass of the gas at a given temperature compared with the mass of an equal volume of gas at the same temperature at a different given temperature
Answer: B — The phenomenon where the stabilty of two stratified layers of liquid of differing relative density distributed resulting in a spomtaneous rapid mixing of the layers accompanied in the case of liquefied gases, by violent vapour evolution
Roll-over is a phenomenon in LNG storage tanks where stratification of two liquid layers of differing densities destabilizes, resulting in sudden, violent mixing and massive boil-off vapor generation.
29. What is Saturated Vapour Pressure?
- A. The pressure at which a vapour is in equilibrium with its liquid at a specific temperature
- B. The mass of the gas at a given temperature compared with the mass of an equal volume of gas at the same temperature at a different given temperature
- C. Heat energy given to or taken from a substance which raises or lowers its temperature
- D. The phenomenon where the stabilty of two stratified layers of liquid of differing relative density distributed resulting in a spomtaneous rapid mixing of the layers accompanied in the case of liquefied gases, by violent vapour evolution
Answer: A — The pressure at which a vapour is in equilibrium with its liquid at a specific temperature
Saturated Vapor Pressure is the equilibrium pressure exerted by the vapor phase above its liquid in a closed system at a specific temperature.
30. What is sensible heat?
- A. The liquid resisting outer element of a cargo containment system designed to provide temporary containment of a leakage of liquid cargothrough the primary barrier
- B. The phenomenon where the stabilty of two stratified layers of liquid of differing relative density distributed resulting in a spomtaneous rapid mixing of the layers accompanied in the case of liquefied gases, by violent vapour evolution
- C. The pressure at which a vapour is in equilibrium with its liquid at a specific temperature
- D. Heat energy given to or taken from a substance which raises or lowers its temperature
Answer: D — Heat energy given to or taken from a substance which raises or lowers its temperature
Sensible heat is thermal energy transferred to or from a substance that results in a measurable change in temperature without changing its physical phase.
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