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LGTCO/LGTF exit exam questions and answers

All 159 questions from the Liquefied Gas Tanker Cargo Operations (LGTCO/LGTF) 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.

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Set 1 — 30 LGTCO/LGTF exit exam questions with answers

1. What does LGTF stand for in maritime STCW training?

  • A. Low Temp Facility
  • B. Liquid Gas Fleet
  • C. Gas Tanker Firefighting
  • D. Basic Training for Liquefied Gas Tanker Cargo Operations
Answer: D — Basic Training for Liquefied Gas Tanker Cargo Operations
LGTF provides basic STCW V/1-2 training for gas carrier personnel.

2. What are the two main categories of liquefied gas cargoes carried in bulk?

  • A. Water and Palm Oil
  • B. HFO and Diesel
  • C. LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas)
  • D. Crude and Bitumen
Answer: C — LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas)
LNG (mostly Methane) and LPG (Propane, Butane, Ammonia) represent the main gas trades.

3. What is cryogenic temperature range in gas shipping?

  • A. 0°C
  • B. Ambient +20°C
  • C. Extremely low temperatures below -50°C (e.g. LNG at -162°C)
  • D. Above +100°C
Answer: C — Extremely low temperatures below -50°C (e.g. LNG at -162°C)
Cryogenic liquids exist at ultra-low temperatures requiring special alloy metallurgy.

4. What injury occurs if human skin contacts cryogenic liquid gas?

  • A. Severe frostbite / Cold thermal burns
  • B. Sunburn
  • C. Skin tanning
  • D. Heat stroke
Answer: A — Severe frostbite / Cold thermal burns
Cryogenic liquids freeze body tissue instantly, causing severe frostbite burns.

5. What happens to liquid gas if spilled onto seawater?

  • A. Rapid boiling and phase change into large gas vapor clouds
  • B. Sinks as solid rock
  • C. Dissolves into salt
  • D. Turns into diesel
Answer: A — Rapid boiling and phase change into large gas vapor clouds
Cryogenic liquid absorbs heat from sea water, expanding rapidly into gas clouds.

6. How is LPG maintained liquid at ambient temperature in pressurized ships?

  • A. High pressure inside Type C pressure vessel tanks (~18 bar)
  • B. Mixing with sand
  • C. Steam heating
  • D. Adding salt
Answer: A — High pressure inside Type C pressure vessel tanks (~18 bar)
Pressurized LPG carriers hold cargo at ambient temp under high pressure (~18 bar).

7. What gas detector measures low levels of flammable gas in air?

  • A. Hydrometer
  • B. Salinometer
  • C. Explosimeter (Combustible Gas Indicator)
  • D. Thermocouple
Answer: C — Explosimeter (Combustible Gas Indicator)
Explosimeters measure flammable gas concentrations as % LEL.

8. What code sets international safety standards for gas carrier construction?

  • A. IBC Code
  • B. IMDG Code
  • C. IGC Code
  • D. IMSBC Code
Answer: C — IGC Code
The International Gas Carrier (IGC) Code governs gas ship design and operation.

9. What is the liquid-to-gas expansion ratio of LNG when vaporized at atmospheric pressure?

  • A. Approximately 1 : 600
  • B. 1 : 2
  • C. 1 : 10
  • D. 1 : 10000
Answer: A — Approximately 1 : 600
1 volume of liquid LNG expands into ~600 volumes of methane gas at ambient conditions.

10. What safety system protects ship structure from cryogenic liquid leaks on deck?

  • A. Foam blanket
  • B. Steam barrier
  • C. Water spray curtain system
  • D. Air curtain
Answer: C — Water spray curtain system
Water spray curtains provide heat shielding and warm up spilled gas liquid.

11. Under STCW Code Table A-V/1-2, what is the mandatory requirement regarding regulatory compliance and STCW code requirements during Advanced Liquefied Gas Operations operations?

  • A. Strict compliance with approved safety procedures and flag state regulations
  • B. Applicable only during drydock operations
  • C. Verbal recommendation without documentation
  • D. Optional adherence based on vessel size
Answer: A — Strict compliance with approved safety procedures and flag state regulations
STCW Code Table A-V/1-2 mandates strict compliance with approved safety protocols for Advanced Liquefied Gas Operations.

12. What specific safety precaution must be observed when managing regulatory compliance and STCW code requirements for Advanced Liquefied Gas Operations on board?

  • A. Conducting a thorough risk assessment and briefing all involved personnel prior to starting work
  • B. Delegating tasks exclusively to untrained crew members
  • C. Proceeding without informing the officer on watch
  • D. Disabling automated safety alarms to save time
Answer: A — Conducting a thorough risk assessment and briefing all involved personnel prior to starting work
Risk assessments and pre-job briefings ensure all team members understand hazards during Advanced Liquefied Gas Operations operations.

13. What PPE is required when connecting cryogenic cargo hoses?

  • A. Raincoat
  • B. Bare hands
  • C. Insulated cryogenic gloves, face shield, safety boots, and full coveralls
  • D. Cotton gloves
Answer: C — Insulated cryogenic gloves, face shield, safety boots, and full coveralls
Cryogenic gloves and face protection guard against cold liquid sprays and frostbite.

14. What gas is used to purge oxygen from cargo tanks before loading gas?

  • A. Compressed air
  • B. Oxygen
  • C. Inert gas or Nitrogen (N2)
  • D. Carbon monoxide
Answer: C — Inert gas or Nitrogen (N2)
Inerting reduces oxygen concentration below 5% to prevent flammable mixtures.

15. What is boil-off gas (BOG)?

  • A. Boiler steam
  • B. Compressed air
  • C. Engine exhaust
  • D. Vapor generated continuously due to heat ingress through tank insulation
Answer: D — Vapor generated continuously due to heat ingress through tank insulation
BOG forms constantly as cryogenic liquid absorbs small amounts of heat.

16. What risk occurs if liquid gas is trapped between two closed line valves?

  • A. Vacuum formation
  • B. Hydraulic expansion pressure rise bursting the pipe line
  • C. Permanent freezing
  • D. Pipe color change
Answer: B — Hydraulic expansion pressure rise bursting the pipe line
Warming liquid gas expands immensely; thermal relief valves prevent pipe rupture.

17. What is the function of an Emergency Shutdown (ESD) system on gas carriers?

  • A. Drop anchor
  • B. Open tank lids
  • C. Turn off lights
  • D. Stop pumps/compressors and close ESD manifold valves in emergency
Answer: D — Stop pumps/compressors and close ESD manifold valves in emergency
ESD systems isolate cargo lines within 30 seconds of emergency trip activation.

18. What gas property makes Ammonia (NH3) hazardous to crew?

  • A. Odorless and sweet
  • B. Inert behavior
  • C. Severe toxicity, respiratory irritation, skin burns, and suffocating odor
  • D. Heavy soot
Answer: C — Severe toxicity, respiratory irritation, skin burns, and suffocating odor
Ammonia is toxic, reactive with copper, and corrosive to human tissue.

19. What fire extinguisher type is installed on gas carrier cargo decks?

  • A. Foam monitors only
  • B. Dry Chemical Powder (DCP)
  • C. Sand buckets
  • D. Soda-acid
Answer: B — Dry Chemical Powder (DCP)
DCP is specified under IGC Code as primary extinguishing agent for gas fires.

20. What device measures tank insulation space gas leaks?

  • A. Thermometer
  • B. Continuous gas sampling and differential pressure monitoring system
  • C. Sounding tape
  • D. Salinometer
Answer: B — Continuous gas sampling and differential pressure monitoring system
Hold spaces and insulation layers are continuously sampled for trace gas leakage.

21. What is the danger of cold methane gas clouds near deck level?

  • A. Non-flammable
  • B. Cold methane is heavier than air initially, forming low flammable vapor clouds
  • C. Floats to space instantly
  • D. Turns to water drops
Answer: B — Cold methane is heavier than air initially, forming low flammable vapor clouds
Cold methane gas (-162°C) is denser than air and stays low until warmed.

22. What first aid treatment is given for cryogenic frostbite on hands?

  • A. Immerse in warm water bath (40°C - 42°C); DO NOT rub
  • B. Apply grease
  • C. Hold near open fire
  • D. Rub with snow
Answer: A — Immerse in warm water bath (40°C - 42°C); DO NOT rub
Warm water rewarming (40-42°C) restores circulation without causing tissue damage.

23. Which international regulation specifies the minimum standard for regulatory compliance and STCW code requirements concerning Advanced Liquefied Gas Operations?

  • A. Port State Control advisory note only
  • B. International Load Line Certificate Annex 3
  • C. STCW Code Section A-V/1-2 and relevant SOLAS/MARPOL conventions
  • D. Tonnage Measurement Convention 1969
Answer: C — STCW Code Section A-V/1-2 and relevant SOLAS/MARPOL conventions
STCW Code Section A-V/1-2 sets international standards for training and operational competency in Advanced Liquefied Gas Operations.

24. In the event of an emergency involving regulatory compliance and STCW code requirements during Advanced Liquefied Gas Operations tasks, what immediate action is required?

  • A. Attempt to resolve the incident silently without raising the alarm
  • B. Wait until the end of the watch to log the issue
  • C. Evacuate the vessel immediately without informing the bridge
  • D. Raise the alarm, notify the Officer of the Watch, and execute assigned muster list duties
Answer: D — Raise the alarm, notify the Officer of the Watch, and execute assigned muster list duties
Prompt alarm activation ensures emergency response teams can mobilize immediately.

25. What is the function of cargo reliquefaction plants on LPG tankers?

  • A. Vent gas into ocean
  • B. Compress and cool boil-off gas, returning it as liquid to cargo tanks
  • C. Burn BOG in boilers
  • D. Convert LPG to diesel
Answer: B — Compress and cool boil-off gas, returning it as liquid to cargo tanks
Reliquefaction units condense BOG back into liquid LPG to control tank pressure.

26. What containment system uses self-supporting spherical aluminum tanks?

  • A. Gaztransport membrane
  • B. Technigaz Mark III
  • C. Moss Rosenberg spherical system
  • D. Flat bottom tank
Answer: C — Moss Rosenberg spherical system
Moss spheres are independent Type B tanks recognized by spherical domes.

27. What safety checklist must be completed before gas cargo operations?

  • A. Bill of Lading
  • B. Custom Manifest
  • C. SIGTTO / ISGOTT Ship-Shore Safety Checklist
  • D. Passenger List
Answer: C — SIGTTO / ISGOTT Ship-Shore Safety Checklist
The Ship-Shore Safety Checklist ensures manifold, ESD, and fire systems are verified.

28. What is the Lower Explosive Limit (LEL) of Methane gas in air?

  • A. 0.1%
  • B. 50%
  • C. 20%
  • D. Approximately 5% by volume
Answer: D — Approximately 5% by volume
Methane becomes flammable in air starting at 5% volume concentration (LEL).

29. What risk is associated with sudden temperature drop during cargo tank cool-down?

  • A. Paint peeling
  • B. Rust growth
  • C. Short circuit
  • D. Thermal shock cracking of tank metal bulkheads and pipe joints
Answer: D — Thermal shock cracking of tank metal bulkheads and pipe joints
Rapid uneven cooling causes high thermal stresses leading to structural metal fractures.

30. What device stops cargo flow automatically if loading arms move beyond safe limits?

  • A. Emergency Release Coupling (ERC) / PERS
  • B. Non-return flap
  • C. Hand valve
  • D. Butterfly valve
Answer: A — Emergency Release Coupling (ERC) / PERS
PERS/ERC isolates and uncouples loading arms instantly during emergency breakaway.

Set 2 — 30 LGTCO/LGTF exit exam questions with answers

1. What is the role of Nitrogen padding in gas shipping?

  • A. Clean deck
  • B. Warm up cargo
  • C. Increase density
  • D. Maintain positive dry inert gas pressure over cargo or insulation spaces
Answer: D — Maintain positive dry inert gas pressure over cargo or insulation spaces
Dry Nitrogen padding prevents moisture ingress and eliminates flammable atmospheres.

2. What instrument measures oxygen content in gas samples?

  • A. Explosimeter
  • B. Hygrometer
  • C. Barometer
  • D. Paramagnetic or Electrochemical Oxygen Analyzer
Answer: D — Paramagnetic or Electrochemical Oxygen Analyzer
Paramagnetic oxygen analyzers accurately measure O2 concentrations in gas mixtures.

3. What is the purpose of deck water spray curtains during gas leaks?

  • A. Knock down gas clouds, cool structural steel, and shield radiant heat
  • B. Fill drinking tanks
  • C. Clean anchor chain
  • D. Wash windows
Answer: A — Knock down gas clouds, cool structural steel, and shield radiant heat
Water sprays absorb heat, disperse vapors, and protect hull steel from cold brittle fracture.

4. Who oversees gas cargo watchkeeping and manifold transfers on board?

  • A. Deck Cadet
  • B. Steward
  • C. Chief Cook
  • D. Chief Officer / Designated Cargo Officer
Answer: D — Chief Officer / Designated Cargo Officer
The Chief Officer manages all gas cargo operations and safety enforcement.

5. How frequently must operational drills and practical checks for regulatory compliance and STCW code requirements be conducted for Advanced Liquefied Gas Operations?

  • A. Annually prior to vessel drydocking
  • B. At least monthly or as mandated by SOLAS and shipboard safety management system (SMS)
  • C. Only when requested by port State control inspectors
  • D. Once every 5 years during special survey
Answer: B — At least monthly or as mandated by SOLAS and shipboard safety management system (SMS)
Regular drills maintain crew emergency readiness and satisfy SOLAS requirements.

6. What documented record must be maintained on board following completion of tasks related to regulatory compliance and STCW code requirements in Advanced Liquefied Gas Operations?

  • A. Verbal update to port agent without logging
  • B. No written record is required
  • C. Entry in the official Deck or Engine Logbook recording date, time, and operational parameters
  • D. Unsigned note on the shipboard notice board
Answer: C — Entry in the official Deck or Engine Logbook recording date, time, and operational parameters
Official logbook entries provide mandatory legal documentation of shipboard safety tasks.

7. What is the primary component of LPG Commercial Propane?

  • A. Hydrogen
  • B. Propane (C3H8)
  • C. Oxygen
  • D. Methane (CH4)
Answer: B — Propane (C3H8)
Commercial LPG propane consists mainly of propane gas.

8. At atmospheric pressure, what is the boiling point of propane?

  • A. +100°C
  • B. 42°C
  • C. 162°C
  • D. 0°C
Answer: B — 42°C
Propane boils at -42.1°C under normal atmospheric pressure.

9. What danger is posed by Nitrogen gas leaking into enclosed accommodation spaces?

  • A. Rapid asphyxiation and death without warning due to oxygen deficiency
  • B. Skin itching
  • C. Explosive fire
  • D. High noise
Answer: A — Rapid asphyxiation and death without warning due to oxygen deficiency
Nitrogen displaces air quietly, causing sudden unconsciousness and hypoxia.

10. What type of insulation is used in Technigaz Mark III membrane LNG tanks?

  • A. Fiberglass wool
  • B. Concrete blocks
  • C. Reinforced polyurethane foam (R-PUF) panels with triplex secondary barrier
  • D. Styrofoam cups
Answer: C — Reinforced polyurethane foam (R-PUF) panels with triplex secondary barrier
Mark III uses rigid polyurethane foam insulation panels faced with flexible secondary barriers.

11. What device measures liquid level in LNG tanks without mechanical contact?

  • A. Sight glass
  • B. Sounding tape
  • C. Radar ullage level gauge
  • D. Dipstick
Answer: C — Radar ullage level gauge
Radar gauges transmit microwave signals through tank vapor to measure exact liquid ullage.

12. What requirement applies to electrical equipment installed in gas carrier hazardous zones?

  • A. Household switches allowed
  • B. No certification needed
  • C. Must be certified intrinsically safe (Ex-i) or explosion-proof (Ex-d)
  • D. Bare wires permitted
Answer: C — Must be certified intrinsically safe (Ex-i) or explosion-proof (Ex-d)
Hazardous areas mandate explosion-proof/intrinsically safe electrical apparatus.

13. What is the function of the gas combustion unit (GCU) on an LNG carrier?

  • A. Generate water
  • B. Safely burn excess boil-off gas when engines cannot consume it
  • C. Warm crew cabins
  • D. Cool down tanks
Answer: B — Safely burn excess boil-off gas when engines cannot consume it
GCUs incinerate excess BOG safely to prevent venting methane into atmosphere.

14. What is the upper explosive limit (UEL) of Methane gas in air?

  • A. 2%
  • B. 100%
  • C. 50%
  • D. Approximately 15% by volume
Answer: D — Approximately 15% by volume
Methane flammable range in air is 5% (LEL) to 15% (UEL) by volume.

15. What action is taken if a gas detector alarm activates in the compressor room?

  • A. Evacuate room, trip compressor ESD, and investigate cause upwind with SCBA
  • B. Open window and smoke
  • C. Turn off bell
  • D. Ignore alarm
Answer: A — Evacuate room, trip compressor ESD, and investigate cause upwind with SCBA
Gas alarms signal dangerous hydrocarbon leaks requiring immediate ESD isolation.

16. What publication provides emergency medical guidance for chemical/gas casualties?

  • A. COLREG 1972
  • B. Medical First Aid Guide (MFAG)
  • C. Port Tariff Manual
  • D. Engine Telegraph Guide
Answer: B — Medical First Aid Guide (MFAG)
MFAG details emergency treatments and antidote administration for toxic gas exposures.

17. What type of personal protective equipment (PPE) is essential when handling regulatory compliance and STCW code requirements under Advanced Liquefied Gas Operations guidelines?

  • A. Certified task-specific PPE meeting SOLAS/IMO performance standards
  • B. Standard street clothing with rubber gloves
  • C. High-visibility vest only
  • D. Basic cotton coveralls without eye or foot protection
Answer: A — Certified task-specific PPE meeting SOLAS/IMO performance standards
Approved PPE protects personnel against specific physical and chemical hazards.

18. What parameter must be verified prior to authorizing enclosed space entry for regulatory compliance and STCW code requirements related to Advanced Liquefied Gas Operations?

  • A. Temperature check only
  • B. Oxygen level at 15% with ventilation turned off
  • C. Visual inspection through access hatch without gas testing
  • D. Atmospheric oxygen level at 20.9% and zero toxic/flammable gas concentration
Answer: D — Atmospheric oxygen level at 20.9% and zero toxic/flammable gas concentration
Enclosed space safety requires verified atmospheric gas testing prior to entry.

19. What is the density of Methane gas at ambient temperature compared to air?

  • A. Same as water
  • B. Heavier than lead
  • C. Heavier than air
  • D. Lighter than air (relative density ~0.55)
Answer: D — Lighter than air (relative density ~0.55)
Warm methane gas is lighter than air (~0.55 SG) and disperses upward.

20. What is the density of Propane vapor at ambient temperature compared to air?

  • A. Lighter than air
  • B. Same as helium
  • C. Heavier than air (relative density ~1.5)
  • D. Zero weight
Answer: C — Heavier than air (relative density ~1.5)
Propane vapor is 1.5 times heavier than air, collecting in low deck areas and bilges.

21. Why is water prohibited for extinguishing liquid gas jet fires at manifold valves unless flow is stopped first?

  • A. Water ruins paint
  • B. Water freezes gas
  • C. Water turns gas to oil
  • D. Extinguishing flame without stopping gas flow creates unignited gas cloud explosion hazard
Answer: D — Extinguishing flame without stopping gas flow creates unignited gas cloud explosion hazard
Extinguishing gas flames while gas keeps escaping creates huge explosive vapor clouds.

22. What equipment measures dew point (moisture) in Nitrogen or inert gas?

  • A. Manometer
  • B. Pyrometer
  • C. Hydrometer
  • D. Dew point meter / Hygrometer
Answer: D — Dew point meter / Hygrometer
Hygrometers verify dry inert gas (-40°C to -60°C dew point) to prevent ice hydrates.

23. What is the function of a thermal relief valve fitted on liquid gas lines?

  • A. Pump bilges
  • B. Relieve small liquid expansion pressure when trapped between closed line valves
  • C. Cool main engine
  • D. Measure depth
Answer: B — Relieve small liquid expansion pressure when trapped between closed line valves
Thermal relief valves vent tiny liquid quantities to prevent explosive line pressure.

24. What safety system automatically closes manifold valves if ship moves beyond safe berthing limits?

  • A. Rudder indicator
  • B. Anchor drop switch
  • C. Emergency Shutdown (ESD) / Emergency Release System (ERS)
  • D. Auto-pilot
Answer: C — Emergency Shutdown (ESD) / Emergency Release System (ERS)
ERS links monitor vessel movement and trip ESD before loading arm physical limits are exceeded.

25. What gas is produced by incomplete combustion in inert gas generators?

  • A. Argon
  • B. Carbon Monoxide (CO)
  • C. Pure Oxygen
  • D. Helium
Answer: B — Carbon Monoxide (CO)
Incomplete combustion releases toxic Carbon Monoxide (CO) gas.

26. What is the purpose of hold space inerting on LPG tankers?

  • A. Store fresh water
  • B. Prevent flammable atmosphere in void space surrounding cargo tanks
  • C. Wash hold steel
  • D. Keep hold warm
Answer: B — Prevent flammable atmosphere in void space surrounding cargo tanks
Inerting hold spaces eliminates oxygen, preventing fires if cargo leaks from primary tank.

27. What signal alerts crew to immediately evacuate an enclosed space?

  • A. Evacuation alarm sounder / radio order from standby person
  • B. Whistle signal
  • C. Dinner bell
  • D. One short horn blast
Answer: A — Evacuation alarm sounder / radio order from standby person
Standby watchkeepers order immediate evacuation if gas levels rise or ventilation fails.

28. Who is responsible for ensuring all gas tanker crew receive proper safety familiarization?

  • A. Customs Officer
  • B. The Ship's Master and Chief Officer
  • C. Shore crane driver
  • D. Port Agent
Answer: B — The Ship's Master and Chief Officer
Master and safety officers enforce mandatory STCW familiarization before crew start duties.

29. What key responsibility belongs to seafarers performing watchkeeping duties for regulatory compliance and STCW code requirements under Advanced Liquefied Gas Operations?

  • A. Continuous monitoring of operational parameters and immediate reporting of anomalies
  • B. Operating equipment beyond design pressure limits
  • C. Bypassing safety trips during routine operations
  • D. Leaving watchkeeping station unattended
Answer: A — Continuous monitoring of operational parameters and immediate reporting of anomalies
Continuous vigilance and prompt communication are core watchkeeping duties under STCW.

30. Which document contains detailed hazard data and emergency handling instructions for substances involved in regulatory compliance and STCW code requirements during Advanced Liquefied Gas Operations?

  • A. Ship's Cargo Manifest summary page
  • B. Crew List document
  • C. Bill of Lading description
  • D. Safety Data Sheet (SDS) / Material Safety Data Sheet (MSDS)
Answer: D — Safety Data Sheet (SDS) / Material Safety Data Sheet (MSDS)
Safety Data Sheets provide critical hazard identification, PPE requirements, and first aid response steps.

Set 3 — 30 LGTCO/LGTF exit exam questions with answers

1. Liquefied gas tankers are categorized as per the cargoes carried, as follows:

  • A. LPG ships, LEG ships, LNG ships, Chlorine ships, LPG / Chemical ships
  • B. LPG ships, Reefer Container ships, Bulk carriers
  • C. Fully pressurized ships, Semi-pressurized ships, Fully refrigerated ships
  • D. Oil tankers, Ro-Ro carriers, Chemical carriers
Answer: A — LPG ships, LEG ships, LNG ships, Chlorine ships, LPG / Chemical ships
Liquefied gas carriers are categorized by their specific cargo types: LPG (Liquefied Petroleum Gas), LEG (Liquefied Ethylene Gas), LNG (Liquefied Natural Gas), Chlorine carriers, and combined LPG/Chemical gas carriers.

2. There are three types of gas tankers according to the carriage condition, such as:

  • A. LPG ships, Reefer ships, Container ships
  • B. LPG ships, LEG ships, LNG ships
  • C. Chlorine ships, LPG/Chemical ships, Reefer container ships
  • D. Fully pressurized ships, Semi-pressurized ships, Fully refrigerated ships
Answer: D — Fully pressurized ships, Semi-pressurized ships, Fully refrigerated ships
Gas tankers are classified by thermodynamic carriage conditions into: Fully Pressurized (ambient temperature), Semi-Pressurized (refrigerated with intermediate pressure), and Fully Refrigerated (cryogenic boiling point at atmospheric pressure).

3. The cargo area of a gas tanker which is not equipped in an approved manner to ensure that its atmosphere is at all times maintained in a safe manner is a:

  • A. Gas-safe space
  • B. Airlock
  • C. Gas-dangerous space
  • D. Machinery space
Answer: C — Gas-dangerous space
Under the IGC Code, a gas-dangerous space is any space or zone not equipped in an approved manner to guarantee that its atmosphere is continuously maintained in a gas-safe condition.

4. A space other than a gas-dangerous space is known as:

  • A. Airlock
  • B. Air handling unit
  • C. Enclosed space
  • D. Gas-safe space
Answer: D — Gas-safe space
The IGC Code defines a gas-safe space as any space on board a gas tanker other than a gas-dangerous space, maintained with positive pressure ventilation or located outside hazardous zones.

5. Air intakes for accommodation and engine-room have to be at a minimum safe distance from ventilation outlets from:

  • A. Gas-dangerous spaces
  • B. Gas-safe spaces
  • C. Main deck
  • D. Airlocks
Answer: A — Gas-dangerous spaces
Air intakes for accommodation, service, and machinery spaces must be situated at prescribed minimum safe distances from ventilation outlets of gas-dangerous spaces to prevent vapor ingress.

6. Can hot work in dangerous and hazardous areas be carried out during cargo, tank cleaning, gas freeing, purging or inerting operations?

  • A. Yes, with general supervision
  • B. No, hot work is strictly prohibited during these operations
  • C. Can be carried out as long as a cold work permit is obtained
  • D. Yes, provided the fire main is pressurized
Answer: B — No, hot work is strictly prohibited during these operations
Hot work is strictly prohibited in gas-dangerous and hazardous areas during cargo transfer, tank cleaning, gas freeing, purging, or inerting operations due to extreme explosion risks.

7. Access from a gas-dangerous zone on the open weather deck to a gas-safe space is arranged through:

  • A. The accommodation alleyway
  • B. An airlock
  • C. The motor room
  • D. The compressor room
Answer: B — An airlock
Access between a gas-dangerous weather deck zone and a gas-safe space (such as the electric motor room or accommodation) must be arranged through an approved airlock with two gas-tight doors.

8. Airlock doors should be self-closing and must not have hooks or hold-open devices. There should be a minimum distance of at least _____ between both doors.

  • A. 0.5 metres
  • B. 1.5 metres
  • C. 1.0 metres
  • D. 2.0 metres
Answer: B — 1.5 metres
Under the IGC Code, airlock doors must be self-closing without hold-back devices, and the distance between the two doors must be at least 1.5 metres to prevent simultaneous opening.

9. An audible and visual alarm system gives a warning on both sides of the airlock when:

  • A. More than one door is moved from the closed position
  • B. One door is moved from the closed position
  • C. One door cannot be opened
  • D. Both doors cannot be opened
Answer: A — More than one door is moved from the closed position
The airlock safety system activates audible and visual alarms on both sides if more than one door is opened or moved from the closed position simultaneously.

10. The gas-safe and airlock spaces within the cargo area have:

  • A. Negative pressure ventilation
  • B. Positive pressure ventilation
  • C. Natural ventilation
  • D. Air conditioning only without positive pressure
Answer: B — Positive pressure ventilation
Gas-safe spaces and airlocks situated within the cargo area are equipped with mechanical positive pressure ventilation to prevent flammable and toxic gas ingress.

11. When the over-pressure of an airlock or gas-safe space is lost:

  • A. All electrical equipment that is not of a certified safe type should be de-energized
  • B. All electrical equipment that is of a certified safe type should be de-energized
  • C. All electrical equipment should continue running without interruption
  • D. All electrical equipment, both certified and non-certified, must be de-energized immediately
Answer: A — All electrical equipment that is not of a certified safe type should be de-energized
If positive overpressure is lost in an airlock or gas-safe space, all non-certified electrical equipment must be automatically or manually de-energized to eliminate ignition sources.

12. Segregation, separation and airlocks are fundamental to the safety of:

  • A. Oil tankers
  • B. Gas tankers
  • C. Chemical tankers
  • D. Container ships
Answer: B — Gas tankers
Atmospheric segregation, physical separation, and pressurized airlocks are fundamental design and operational safety barriers on liquefied gas tankers.

13. Can LNG and LPG be used as fuel in a ship's engine room?

  • A. Only LPG can be used
  • B. Only LNG can be used
  • C. Yes, both can be used under relevant IGF/IGC Code requirements
  • D. No, none can be used
Answer: C — Yes, both can be used under relevant IGF/IGC Code requirements
Both LNG and LPG are approved for use as marine engine fuel under the IMO IGF Code and IGC Code, subject to specialized double-wall piping, leak detection, and safety interlocks.

14. List the dryers used with an Inert Gas Generator on gas ships to dry the inert gas generated:

  • A. Refrigerated drier and absorption (desiccant) drier
  • B. Only refrigerated dryer
  • C. Only absorption dryer
  • D. None of the above; only demister pads are used
Answer: A — Refrigerated drier and absorption (desiccant) drier
Inert gas generators on gas carriers utilize a two-stage drying plant: a refrigerated dryer to cool gas and condense bulk water (+5°C), followed by an adsorption desiccant dryer (activated alumina) to achieve low dew points (-45°C to -65°C).

15. Can cargo be loaded if the MSDS (Material Safety Data Sheet) for the cargo is not supplied by the shipper or terminal?

  • A. Yes, if cargo details are verbally communicated
  • B. No, cargo must not be loaded without the official MSDS
  • C. Yes, it does not make a difference
  • D. Yes, provided the vessel has loaded similar cargo before
Answer: B — No, cargo must not be loaded without the official MSDS
SOLAS and the IGC Code strictly mandate that cargo operations must not commence until an official Material Safety Data Sheet (MSDS/SDS) detailing physical and chemical hazards is provided.

16. What is the atmospheric boiling point of Methane?

  • A. -0.5°C
  • B. -104°C
  • C. -161.5°C
  • D. -41.5°C
Answer: C — -161.5°C
Methane (CH4), the primary constituent of LNG, has an atmospheric boiling point of -161.5°C (-162°C), requiring fully refrigerated cryogenic carriage.

17. What is the atmospheric boiling point of Butane (n-Butane)?

  • A. -0.5°C
  • B. -42°C
  • C. -88.6°C
  • D. -104°C
Answer: A — -0.5°C
Normal butane (n-C4H10) has an atmospheric boiling point of -0.5°C, allowing it to be easily liquefied at modest refrigeration or pressure.

18. What is the vapour relative density of Methane? (Air = 1)

  • A. 1.058
  • B. 0.554
  • C. 1.55
  • D. 2.09
Answer: B — 0.554
At ambient temperature, methane vapor has a relative density of approximately 0.554 compared to air, meaning warm methane gas is lighter than air and rises rapidly.

19. What is the vapour relative density of Propane? (Air = 1)

  • A. 0.554
  • B. 1.55
  • C. 0.20
  • D. 0.80
Answer: B — 1.55
Propane vapor has a relative density of 1.55 (Air = 1), making it significantly heavier than air and causing it to collect in low deck areas and bilges.

20. What is the vapour relative density of n-Butane? (Air = 1)

  • A. 0.90
  • B. 2.09
  • C. 2.60
  • D. 1.70
Answer: B — 2.09
Normal butane vapor has a relative density of approximately 2.09 (Air = 1), which is more than twice as heavy as air.

21. What is the operation carried out prior to cooling down the tanks on fully refrigerated liquefied gas carriers?

  • A. Gassing up
  • B. Inerting
  • C. Aerating
  • D. Gas freeing
Answer: A — Gassing up
Before cooling down cargo tanks with liquid cargo, tanks must be gassed up with warm cargo vapor to displace inert gas and prevent freezing of CO2 or moisture.

22. What is the operation carried out prior to gassing up the tanks on liquefied gas carriers?

  • A. Gas freeing
  • B. Aerating
  • C. Cooling down
  • D. Inerting
Answer: D — Inerting
Prior to introducing flammable cargo vapor (gassing up), cargo tanks containing air must be thoroughly inerted with inert gas or nitrogen to lower oxygen levels below flammable thresholds.

23. What is the vapour relative density of Chlorine? (Air = 1)

  • A. 2.00
  • B. 2.49
  • C. 1.55
  • D. 0.55
Answer: B — 2.49
Chlorine vapor is heavy and dense, with a relative density of approximately 2.49 (Air = 1), causing toxic clouds to settle in low spaces and hold bottoms.

24. Requirement for cargo tank entry with respect to tank atmosphere check of hydrocarbon content:

  • A. Hydrocarbon content must be more than 10% LFL
  • B. Hydrocarbon content must be less than 1% LFL
  • C. Hydrocarbon content must be above the UFL
  • D. Hydrocarbon content must be between LFL and UFL
Answer: B — Hydrocarbon content must be less than 1% LFL
For safe entry into any gas cargo tank or enclosed space, hydrocarbon vapor content must be tested and verified to be less than 1% of the Lower Flammable Limit (LFL).

25. What is the auto-ignition temperature of Ethylene Oxide?

  • A. 452°C
  • B. 509°C
  • C. 429°C
  • D. 396°C
Answer: C — 429°C
Ethylene Oxide has an auto-ignition temperature of approximately 429°C (804°F) and exhibits wide flammability limits (3% to 100%).

26. What is the auto-ignition temperature of Propylene Oxide?

  • A. 465°C
  • B. 509°C
  • C. 416°C
  • D. 396°C
Answer: A — 465°C
Propylene oxide has an auto-ignition temperature of approximately 465°C (449°C–465°C depending on test standard).

27. What is the critical pressure of Propane in bars absolute?

  • A. 38.1 bar absolute
  • B. 42.6 bar absolute
  • C. 50.2 bar absolute
  • D. 46.2 bar absolute
Answer: B — 42.6 bar absolute
The critical pressure of propane is approximately 42.6 bar absolute (4.26 MPa) at its critical temperature of 96.8°C.

28. What is the critical pressure of n-Butane in bars absolute?

  • A. 38.1 bar absolute
  • B. 42.6 bar absolute
  • C. 52.6 bar absolute
  • D. 32.2 bar absolute
Answer: A — 38.1 bar absolute
The critical pressure of n-butane is approximately 38.1 bar absolute (3.8 MPa) at its critical temperature of 152.0°C.

29. What is the critical pressure of Methane in bars absolute?

  • A. 50.3 bar absolute
  • B. 34.3 bar absolute
  • C. 44.7 bar absolute
  • D. 65.2 bar absolute
Answer: C — 44.7 bar absolute
The critical pressure of methane is approximately 44.7 to 46.0 bar absolute at its critical temperature of -82.5°C.

30. What is known as Inert Gas?

  • A. Non-flammable gases containing insufficient oxygen to support combustion
  • B. Flammable gas with concentration between LEL and UFL limits
  • C. Flammable gas with concentration above UFL limits
  • D. Toxic gas having concentration percentage below TLV-TWA
Answer: A — Non-flammable gases containing insufficient oxygen to support combustion
Inert gas is defined as a gas or mixture of non-flammable gases (such as nitrogen or combustion flue gas) containing insufficient oxygen to support the combustion of hydrocarbons.

Set 4 — 30 LGTCO/LGTF exit exam questions with answers

1. What is the critical pressure of Ethylene in bars absolute?

  • A. 46.2 bar absolute
  • B. 38.8 bar absolute
  • C. 50.5 bar absolute
  • D. 42.6 bar absolute
Answer: C — 50.5 bar absolute
The critical pressure of ethylene is approximately 50.5 bar absolute (5.05 MPa) at its critical temperature of 9.9°C.

2. An LNG fire is classified under which class of fire in maritime STCW standards?

  • A. Class A fire
  • B. Class B fire
  • C. Class C fire
  • D. Class D fire
Answer: C — Class C fire
Under standard international and European/ISO fire classifications used in STCW maritime training, flammable gas fires (including LNG and LPG methane vapor fires) are categorized as Class C fires.

3. Which fixed fire-fighting system is mandatory for fire-fighting on the cargo deck of a liquefied gas carrier?

  • A. Fixed low-expansion foam system
  • B. Fixed dry chemical powder (DCP) system
  • C. Fixed CO2 flooding system
  • D. Fixed wet chemical fire-fighting system
Answer: B — Fixed dry chemical powder (DCP) system
The IGC Code mandates the installation of a fixed dry chemical powder (DCP) extinguishing system on the cargo area deck of all liquefied gas carriers.

4. What should crew members do immediately when the ship's General Emergency Alarm sounds?

  • A. Wear PPE, lifejacket, carry immersion suit and go to the navigation bridge
  • B. Wear PPE, lifejacket, carry immersion suit and go to the engine control room
  • C. Wear PPE, lifejacket, carry immersion suit and proceed to the forecastle
  • D. Wear PPE, lifejacket, carry immersion suit and proceed to the designated Muster Point as per the Ship's Muster List
Answer: D — Wear PPE, lifejacket, carry immersion suit and proceed to the designated Muster Point as per the Ship's Muster List
Upon hearing the general emergency alarm, all personnel must don proper warm clothing and lifejackets, carry their immersion suits, and muster immediately at their designated muster station.

5. What is Critical Temperature?

  • A. The temperature above which a gas cannot be liquefied by pressure alone
  • B. The temperature at which a gas changes state to liquid at atmospheric pressure
  • C. The temperature at which a gas becomes superheated
  • D. The temperature at which liquefied gas changes from liquid to gas during boiling
Answer: A — The temperature above which a gas cannot be liquefied by pressure alone
Critical temperature is the specific temperature above which a gas cannot be condensed into liquid form, regardless of the amount of pressure applied.

6. What is Flammable Range?

  • A. A mixture of flammable gas in air whose gas percentage is above the UFL
  • B. The range of hydrocarbon vapor concentration in air between the LFL and UFL capable of burning
  • C. A mixture of flammable gas in air whose gas percentage is below the LFL
  • D. A gas mixture whose concentration is strictly between 0% and 10% LFL
Answer: B — The range of hydrocarbon vapor concentration in air between the LFL and UFL capable of burning
The flammable range is the intermediate concentration span of flammable gas mixed with air (between Lower and Upper Flammable Limits) within which combustion can occur if ignited.

7. What is Flash Point?

  • A. The lowest temperature at which a liquid ignites spontaneously without a spark
  • B. The lowest temperature at which a liquid gives off sufficient vapour to form an ignitable mixture with air near its surface
  • C. The temperature at which a boiling liquid expanding vapor explosion (BLEVE) takes place
  • D. The lowest temperature required for self-sustained spontaneous combustion
Answer: B — The lowest temperature at which a liquid gives off sufficient vapour to form an ignitable mixture with air near its surface
Flash point is the lowest temperature at which a liquid produces enough vapor to form a momentary flammable mixture with air near the surface when exposed to an ignition source.

8. The ship's General Emergency Alarm signal is defined as:

  • A. Three long blasts on the ship's whistle and general alarm bells
  • B. Seven or more short blasts followed by one long blast on the ship's whistle and bells
  • C. Continuous sounding of the ship's whistle for more than 2 minutes
  • D. One continuous long blast followed by two short blasts
Answer: B — Seven or more short blasts followed by one long blast on the ship's whistle and bells
Under SOLAS Chapter III, the standard general emergency alarm signal consists of seven or more short blasts followed by one long blast on the ship's whistle and internal alarm system.

9. What operation is done on fully refrigerated gas carriers before loading liquid cargo?

  • A. Gassing up
  • B. Cooling down
  • C. Inerting
  • D. Aerating
Answer: B — Cooling down
Before loading cryogenic liquid cargo, cargo tanks must be cooled down gradually with liquid cargo spray to minimize thermal stress and prevent excessive boil-off pressure spikes.

10. What operation is done on fully refrigerated gas carriers before gassing up after drydock?

  • A. Drying only
  • B. Inerting
  • C. Cooling down
  • D. Aerating
Answer: B — Inerting
After drydock (when tanks contain air), tanks must be dried and inerted with inert gas or nitrogen to lower oxygen levels below 8% (typically <5%) prior to introducing flammable cargo gas.

11. What is the chemical formula of Vinyl Chloride Monomer (VCM)?

  • A. C2H3Cl
  • B. CH3COCl
  • C. NaClO
  • D. CH4
Answer: A — C2H3Cl
Vinyl chloride monomer has the chemical formula C2H3Cl (chloroethene), a toxic, flammable chemical gas carried in gas carriers.

12. What is the chemical formula of Methane?

  • A. C2H6
  • B. CH4
  • C. C3H8
  • D. C2H4
Answer: B — CH4
Methane, the simplest alkane and primary component of natural gas, has the chemical formula CH4.

13. How many pressure relief valves must be fitted for cargo tanks above 20 m³ capacity on gas carriers?

  • A. At least one relief valve
  • B. At least two relief valves
  • C. At least three relief valves
  • D. At least four relief valves
Answer: B — At least two relief valves
The IGC Code Chapter 8 requires that all cargo tanks with a capacity exceeding 20 m³ must be fitted with at least two independent pressure relief valves.

14. The critical temperature for Propane is:

  • A. 96.8°C
  • B. 100.4°C
  • C. 44.5°C
  • D. 32.1°C
Answer: A — 96.8°C
The critical temperature of propane is 96.8°C (206.2°F). Below this temperature, propane can be liquefied by pressure alone.

15. The critical temperature for Methane is:

  • A. 32.1°C
  • B. -82.5°C
  • C. 44.5°C
  • D. -64.8°C
Answer: B — -82.5°C
The critical temperature of methane is -82.5°C. Above -82.5°C, methane cannot be liquefied regardless of how much pressure is applied, which is why LNG must be refrigerated.

16. The critical temperature for Ethylene is:

  • A. 1.2°C
  • B. 19.8°C
  • C. 9.9°C
  • D. 32.1°C
Answer: C — 9.9°C
The critical temperature of ethylene is 9.9°C (283 K), requiring refrigeration on semi-pressurized and fully refrigerated ethylene carriers.

17. Independent Type B tanks on gas carriers are characterized as:

  • A. Completely self-supporting when full or empty
  • B. Self-supporting only when empty
  • C. Self-supporting only when full
  • D. Non-self-supporting membrane structures
Answer: A — Completely self-supporting when full or empty
Independent Type B tanks (such as Moss spherical tanks or SPB prismatic tanks) are fully self-supporting under all load conditions, designed with sophisticated stress analysis requiring only a partial secondary barrier.

18. The maximum allowable tank design pressure in the vapour space for Independent Type A tanks is:

  • A. 0.9 barg
  • B. 0.25 barg
  • C. 0.7 barg
  • D. 18 barg
Answer: C — 0.7 barg
Independent Type A tanks are constructed primarily of planar surfaces; their design vapor space pressure must not exceed 0.7 barg (typically operated below 0.25 barg).

19. The IGC Code stipulates that a secondary barrier must be capable of containing cargo leakage for a period of how many days?

  • A. 10 days
  • B. 15 days
  • C. 30 days
  • D. 45 days
Answer: B — 15 days
Under the IGC Code, the secondary barrier must be capable of safely containing cargo leakage from the primary barrier for at least 15 days under specified sea conditions.

20. Type 'C' tanks are normally spherical or cylindrical pressure vessels having design pressures higher than:

  • A. 0.7 barg
  • B. 2.0 barg
  • C. 1.0 barg
  • D. 5.0 barg
Answer: B — 2.0 barg
Type C tanks are pressure vessels designed according to recognized pressure vessel codes with design vapor pressures generally exceeding 2.0 barg, exempting them from requiring a secondary barrier.

21. Semi-membrane tanks are:

  • A. Completely self-supporting when loaded or empty
  • B. Self-supporting only when loaded
  • C. Self-supporting only when empty
  • D. Non-self-supporting tanks under all conditions
Answer: C — Self-supporting only when empty
Semi-membrane tanks are designed to be self-supporting in the empty condition, but when loaded, hydrostatic cargo loads are transferred through insulation to the supporting ship hull.

22. Liquefied gas is defined by the IGC Code as a liquid having a saturated vapour pressure exceeding:

  • A. 2.8 bar absolute at 37.8°C
  • B. 3.8 bar absolute at 37.8°C
  • C. 2.8 bar absolute at 27.8°C
  • D. 3.8 bar absolute at 27.8°C
Answer: A — 2.8 bar absolute at 37.8°C
The IGC Code defines liquefied gases as liquids with a saturated vapor pressure exceeding 2.8 bar absolute at a temperature of 37.8°C (100°F).

23. What is the mode of operation of fixed dry chemical powder (DCP) monitors on gas tanker decks?

  • A. Only locally from deck
  • B. Operation both locally and remotely
  • C. Only remotely from the navigation bridge or CCR
  • D. Automatic thermal sensor activation only
Answer: B — Operation both locally and remotely
IGC Code regulations require deck fixed DCP monitors to be capable of discharge and actuation both locally at the monitor and remotely from a safe location.

24. How many independent fixed DCP units for fire-fighting are required on the deck of a gas carrier of cargo capacity 1,000 m³ and above?

  • A. At least one independent DCP unit
  • B. At least two independent DCP units
  • C. At least three independent DCP units
  • D. At least four independent DCP units
Answer: B — At least two independent DCP units
For gas carriers with a cargo capacity of 1,000 m³ or greater, the fixed dry chemical powder system must consist of at least two independent, self-contained units.

25. What is the minimum discharge time for a deck fixed DCP system with all monitors and hand-held hoses operating?

  • A. 25 seconds
  • B. 35 seconds
  • C. 45 seconds
  • D. 60 seconds
Answer: C — 45 seconds
Under the IGC Code, the stored capacity of dry chemical powder must be sufficient to provide a minimum continuous discharge time of at least 45 seconds.

26. How many monitors are fitted in a fixed DCP installation for deck fire-fighting on gas ships?

  • A. At least one monitor
  • B. At least two monitors
  • C. At least three monitors
  • D. At least four monitors
Answer: C — At least three monitors
Fixed DCP installations are arranged with multiple monitors (typically at least three across manifold and cargo areas) to ensure complete coverage of deck cargo areas from at least two independent directions.

27. What is the atmospheric boiling point of Chlorine?

  • A. -45°C
  • B. -25°C
  • C. -39°C
  • D. -34°C
Answer: D — -34°C
Chlorine (Cl2) has an atmospheric boiling point of approximately -34°C (-29.2°F).

28. What is the atmospheric boiling point of Ammonia (Anhydrous NH3)?

  • A. -33.4°C
  • B. -45.4°C
  • C. -42.4°C
  • D. -29.6°C
Answer: A — -33.4°C
Anhydrous ammonia (NH3) boils at -33.4°C at standard atmospheric pressure.

29. What is the atmospheric boiling point of Propylene (Propene)?

  • A. -42.4°C
  • B. -47.7°C
  • C. -103.9°C
  • D. -63.4°C
Answer: B — -47.7°C
Propylene (C3H6) has an atmospheric boiling point of -47.7°C (-53.9°F).

30. What are Carbamates in gas shipping chemistry?

  • A. A white powdery substance produced by the reaction of ammonia with carbon dioxide
  • B. Compounds formed by the interaction of water and hydrocarbons at certain pressures and temperatures
  • C. Compounds formed by the chemical combination of cargo liquid with oxygen
  • D. The chemical union of two or more identical molecules into a polymer
Answer: A — A white powdery substance produced by the reaction of ammonia with carbon dioxide
Carbamates (ammonium carbamate) are white powdery solids formed when ammonia reacts with carbon dioxide (such as from combustion inert gas), which can severely choke cargo valves and filters.

Set 5 — 30 LGTCO/LGTF exit exam questions with answers

1. What are Gas Hydrates in liquefied gas operations?

  • A. A white powdery substance produced by the reaction of ammonia with carbon dioxide
  • B. Solid crystalline compounds formed by the interaction of water and hydrocarbon gas at specific temperatures and pressures
  • C. Compounds formed by the chemical combination of cargo liquid with atmospheric oxygen
  • D. Polymerized chains of unsaturated alkene molecules
Answer: B — Solid crystalline compounds formed by the interaction of water and hydrocarbon gas at specific temperatures and pressures
Gas hydrates are solid, ice-like crystalline compounds formed when free water molecules trap light hydrocarbon molecules under elevated pressure and low temperatures, risking pipe and valve blockages.

2. What are Peroxides in chemical and gas cargo handling?

  • A. A white powdery substance produced by the reaction of ammonia with carbon dioxide
  • B. Compounds formed by the interaction of water and hydrocarbons at low temperatures
  • C. Unstable, shock-sensitive compounds formed by the reaction of cargo liquid or vapor with atmospheric oxygen
  • D. Non-flammable inert gases used for tank padding
Answer: C — Unstable, shock-sensitive compounds formed by the reaction of cargo liquid or vapor with atmospheric oxygen
Peroxides are hazardous, highly reactive, and potentially explosive compounds formed when unsaturated monomers (like butadiene or vinyl chloride) react with oxygen.

3. Liquefied gas cargo tank contents are bounded directly by the:

  • A. Secondary barrier
  • B. Primary barrier
  • C. Interbarrier space
  • D. Ship's inner hull
Answer: B — Primary barrier
The primary barrier is the inner containment shell or membrane that is in direct contact with and contains the liquid cargo under normal carriage conditions.

4. A device used to determine the liquid-vapour interface during the ullaging of semi-pressurized and fully pressurized tanks is a:

  • A. Radar gauge
  • B. Float gauge
  • C. Capacitance gauge
  • D. Slip tube
Answer: D — Slip tube
Slip tubes are restricted gauging devices fitted on pressurized cargo tanks that penetrate the shell to locate the liquid/vapor interface by observing liquid spray when cracked open.

5. Which of the following is an example of a closed gauging system that does not penetrate the cargo tank shell?

  • A. Slip tube
  • B. Float gauge
  • C. Radar (microwave) gauge
  • D. Nitrogen bubbler gauge
Answer: C — Radar (microwave) gauge
Radar (microwave) level gauges transmit and receive electromagnetic signals through a gas-tight antenna window without physically penetrating or opening the cargo containment barrier.

6. Where on a firefighter wearing SCBA is the fireproof 30-metre lifeline attached?

  • A. Tied around the waist
  • B. Tied to the SCBA air cylinder bottle
  • C. Attached by means of a snap hook to the harness of the apparatus, or to a separate safety belt
  • D. Tied securely around the wrist
Answer: C — Attached by means of a snap hook to the harness of the apparatus, or to a separate safety belt
SOLAS Fire Safety Systems Code requires the 30-metre fireproof lifeline to be fastened by a snap hook directly to the harness of the breathing apparatus or to a dedicated safety belt.

7. Which of the following is a solid desiccant medium that dries gas by adsorption of water molecules?

  • A. Wood shavings
  • B. Cotton fiber
  • C. Activated carbon
  • D. Activated alumina
Answer: D — Activated alumina
Activated alumina (or molecular sieve silica gel) is a highly porous aluminum oxide desiccant that extracts moisture through surface adsorption, achieving dew points below -60°C.

8. The temperature at which condensation will take place within a gas mixture if further cooling occurs is known as:

  • A. Critical temperature
  • B. Dewpoint
  • C. Absolute temperature
  • D. Flash point
Answer: B — Dewpoint
Dewpoint is the saturation temperature at which water vapor (or cargo vapor) in a gas mixture begins to condense into liquid at constant pressure.

9. A gauging system employing a device which penetrates the tank and which, when in use, permits a small quantity of cargo vapour or liquid to escape to atmosphere is known as:

  • A. Closed device which does not penetrate the cargo tank
  • B. Closed device which penetrates the cargo tank
  • C. Restricted gauging device
  • D. Indirect gauging system
Answer: B — Closed device which penetrates the cargo tank
Devices penetrating the tank that release small, controlled quantities of vapor/liquid during measurement (such as slip tubes) are categorized under IGC Code as closed penetrating or restricted gauging systems.

10. Float gauges installed on liquefied gas tankers are an example of which gauging category?

  • A. Closed devices which do not penetrate the cargo tank
  • B. Restricted gauging
  • C. Closed devices which penetrate the cargo tank
  • D. Indirect ullage systems
Answer: B — Restricted gauging
Float gauges on gas ships utilize internal floats and tape mechanisms enclosed in gas-tight housings, categorized under operational standards as restricted/closed penetrating devices.

11. Semi-pressurized ships capable of withstanding carriage temperatures of down to -48°C are designed to carry which cargo?

  • A. LNG
  • B. Ethylene
  • C. Ethane
  • D. LPG (Propane and Butane)
Answer: D — LPG (Propane and Butane)
Semi-pressurized LPG ships with -48°C minimum design temperatures are fully capable of carrying commercial propane (-42.3°C boiling point) and butane (-0.5°C).

12. Semi-pressurized ships capable of withstanding carriage temperatures down to -104°C cannot carry which of the following cargoes?

  • A. Methane (LNG)
  • B. Propane
  • C. Butane
  • D. Ethylene
Answer: A — Methane (LNG)
Methane requires a cryogenic carriage temperature of -161.5°C, which exceeds the -104°C metallurgical limits of ethylene/LPG semi-pressurized carriers.

13. In the case of a typical fully pressurized ship carrying cargo at ambient temperatures, what is the maximum design working pressure of the cargo tanks?

  • A. 0.7 barg
  • B. 18 barg
  • C. 5 to 7 barg
  • D. 9 barg
Answer: B — 18 barg
Fully pressurized gas tankers carry cargoes at ambient temperatures (up to 45°C) without refrigeration, requiring Type C pressure vessels rated for approx. 17.5 to 18 barg.

14. The deepwell or submersible cargo pumps used for pumping liquefied gases are of which design type?

  • A. Rotary vane type
  • B. Gear type
  • C. Reciprocating piston type
  • D. Centrifugal type
Answer: D — Centrifugal type
Liquefied gas cargo pumps are multi-stage centrifugal pumps, driven either by submerged electric motors or top-mounted motors via long vertical shafts.

15. For a typical semi-pressurized ship, cargo tanks and associated equipment are designed for what working pressure?

  • A. Approximately 5 to 7 barg and a vacuum of 0.5 barg
  • B. Approximately 18 barg
  • C. Approximately 9 barg and a vacuum of 1.0 barg
  • D. Approximately 0.7 barg and a vacuum of 1.0 barg
Answer: A — Approximately 5 to 7 barg and a vacuum of 0.5 barg
Semi-pressurized cargo tanks are designed for moderate pressures of 5 to 7 barg (typically 5.5 barg) with a vacuum capability of 0.3 to 0.5 barg.

16. State the typical thickness of the primary metal membrane in membrane LNG tanks:

  • A. 2.0 to 3.7 mm thick
  • B. 0.7 to 1.5 mm thick
  • C. 4.0 to 5.0 mm thick
  • D. 8.5 to 10.0 mm thick
Answer: B — 0.7 to 1.5 mm thick
Membrane containment systems (such as GTT Mark III corrugated stainless steel or NO 96 Invar alloy) use thin metal sheets ranging from 0.7 mm (Invar) to 1.2–1.5 mm (stainless steel).

17. State the carriage temperature for Propane at atmospheric pressure:

  • A. -161.5°C
  • B. -88.6°C
  • C. -42.3°C
  • D. -0.5°C
Answer: C — -42.3°C
On fully refrigerated LPG carriers, commercial propane is transported at its atmospheric boiling point of -42.3°C.

18. State the carriage temperature for Ethylene Oxide at atmospheric pressure:

  • A. 15.8°C
  • B. -7.2°C
  • C. -23.8°C
  • D. 10.7°C
Answer: D — 10.7°C
Ethylene oxide has an atmospheric boiling point of 10.7°C (51.3°F), transported under inert gas padding.

19. State the carriage temperature for Propylene Oxide at atmospheric pressure:

  • A. 9.6°C
  • B. 34.2°C
  • C. -7.2°C
  • D. -10.2°C
Answer: B — 34.2°C
Propylene oxide has an atmospheric boiling point of 34.2°C (93.6°F) and is carried under controlled temperature and inert padding.

20. Dräger detector tubes and hand bellows pump are primarily used to measure which type of gas?

  • A. Toxic gas
  • B. Flammable gas % LEL
  • C. Oxygen percentage
  • D. Inert gas volume
Answer: A — Toxic gas
Dräger colorimetric chemical stain tubes with hand pumps are specialized precision instruments used to detect toxic gases and trace chemical vapors in parts per million (PPM).

21. Which of the following liquefied gases is non-flammable?

  • A. Chlorine
  • B. Ethylene
  • C. Ethylene oxide
  • D. Propylene oxide
Answer: A — Chlorine
Chlorine (Cl2) is a non-flammable, highly toxic and oxidizing liquefied gas. (Ethylene, ethylene oxide, propylene oxide, and ammonia are flammable).

22. Which of the following liquefied gases is categorized as toxic under the IGC Code?

  • A. Ethylene
  • B. Propylene
  • C. Chlorine
  • D. Methane
Answer: C — Chlorine
Chlorine (along with anhydrous ammonia and ethylene oxide) is classified as a toxic liquefied gas under the IGC Code requiring specialized cargo containment and emergency safety systems.

23. The fixed gas-detection system's alarm on a gas carrier is activated when flammable vapour concentration reaches:

  • A. 10% of the Lower Explosive Limit (LEL)
  • B. 30% of the Lower Explosive Limit (LEL)
  • C. 20% of the Lower Explosive Limit (LEL)
  • D. 40% of the Lower Explosive Limit (LEL)
Answer: B — 30% of the Lower Explosive Limit (LEL)
The IGC Code requires fixed gas-detection alarms in enclosed spaces to trigger at not more than 30% of the Lower Explosive Limit (LEL).

24. Which statement correctly applies to Independent Type C cargo tanks?

  • A. A full secondary barrier is required
  • B. No secondary barrier is required
  • C. A partial secondary barrier in the form of a drip tray is always mandatory
  • D. Must be fitted with membrane insulation barriers
Answer: B — No secondary barrier is required
Because Type C pressure vessels are designed against classical pressure vessel design criteria with high safety factors against catastrophic failure, no secondary barrier is required.

25. For safe cargo tank entry, toxic gas concentration must be verified below:

  • A. Less than the OEL (Occupational Exposure Limit)
  • B. Less than 80% of the OEL
  • C. Less than 50% of the OEL / TLV
  • D. Less than 60% of the OEL
Answer: C — Less than 50% of the OEL / TLV
Industry safety guidelines (ISGOTT/SIGTTO) require that toxic gas concentrations must be tested and confirmed below 50% of the Occupational Exposure Limit (OEL/TLV) prior to enclosed space entry.

26. What is the primary extinguishing chemical filled in an ABC-rated Dry Chemical Powder (DCP) extinguisher?

  • A. Potassium bicarbonate
  • B. Sodium bicarbonate
  • C. Mono-ammonium phosphate
  • D. Sodium, magnesium and aluminium powder
Answer: C — Mono-ammonium phosphate
ABC multipurpose dry chemical fire extinguishers are filled with mono-ammonium phosphate powder, which forms a sticky residue that smothers Class A embers and breaks Class B/C chemical chain reactions.

27. What is the chemical powder filled in a standard BC-rated DCP fire extinguisher?

  • A. Potassium bicarbonate urea
  • B. Sodium bicarbonate
  • C. Mono-ammonium phosphate
  • D. Calcium hydroxide
Answer: B — Sodium bicarbonate
Standard BC dry chemical powder extinguishers are filled primarily with sodium bicarbonate (baking soda), highly effective on flammable liquid and gas fires.

28. Under maritime international standards, what class of fire does a flammable gas fire fall under?

  • A. Class A fire
  • B. Class B fire
  • C. Class C fire
  • D. Class D fire
Answer: C — Class C fire
Flammable gas fires (such as methane, propane, butane, or ethylene) are classified as Class C fires in international maritime firefighting standards.

29. Under maritime international standards, what class of fire does a flammable liquid fire fall under?

  • A. Class A fire
  • B. Class B fire
  • C. Class C fire
  • D. Class D fire
Answer: B — Class B fire
Fires involving flammable liquids or liquefiable solids (such as oils, diesel, paint, or solvents) are classified as Class B fires.

30. What is the propellant gas used in fixed dry chemical powder (DCP) fire-fighting systems on gas carrier decks?

  • A. Oxygen
  • B. Compressed atmospheric air
  • C. Acetylene
  • D. Nitrogen
Answer: D — Nitrogen
High-pressure dry Nitrogen (N2) gas cylinders are utilized as the propellant medium to fluidize and discharge dry chemical powder through deck monitors and hand lines.

Set 6 — 9 LGTCO/LGTF exit exam questions with answers

1. Running two identical centrifugal cargo pumps in parallel will result in:

  • A. Almost double the discharge pressure with the same discharge rate
  • B. Almost double the discharge flow rate with discharge pressure largely unchanged
  • C. Double discharge rate and double discharge pressure simultaneously
  • D. The exact same discharge pressure and rate as running one pump
Answer: B — Almost double the discharge flow rate with discharge pressure largely unchanged
Operating centrifugal pumps in parallel increases the total volumetric discharge flow rate (nearly double, depending on system backpressure) while the total discharge head/pressure remains approximately constant.

2. Whether cargo tanks are of Type 'A', 'B' or 'C', a complete double hull is required for carriage of liquefied gas cargoes below what temperature?

  • A. -88°C
  • B. -55°C
  • C. -104°C
  • D. -162°C
Answer: B — -55°C
Under the IGC Code, a complete double hull and double bottom structure surrounding the cargo hold spaces is mandatory for vessels carrying liquefied gases at carriage temperatures below -55°C.

3. What is the minimum water application rate of the fixed water spray system for fire protection purposes on horizontal deck surfaces?

  • A. 10 litres/m² per minute
  • B. 4 litres/m² per minute
  • C. 20 litres/m² per minute
  • D. 15 litres/m² per minute
Answer: A — 10 litres/m² per minute
The IGC Code Chapter 11 requires deck fixed water spray systems to deliver a minimum uniform application rate of 10 litres/m² per minute over horizontal surfaces.

4. What is the minimum water application rate of the fixed water spray system for fire protection purposes on vertical surfaces?

  • A. 8 litres/m² per minute
  • B. 4 litres/m² per minute
  • C. 12 litres/m² per minute
  • D. 15 litres/m² per minute
Answer: B — 4 litres/m² per minute
The IGC Code specifies a minimum water spray delivery rate of 4 litres/m² per minute for vertical surfaces, accommodation bulkheads, and tank domes.

5. In fixed gas-detection systems on board gas carriers, the Gas Codes mandate that sampling intervals from any one space must not exceed:

  • A. 60 minutes
  • B. 30 minutes
  • C. 45 minutes
  • D. 20 minutes
Answer: B — 30 minutes
Where sequential gas sampling systems are used on gas carriers, the interval between consecutive samplings from any individual monitored location must not exceed 30 minutes.

6. What is the name of the statutory certificate issued by a Flag Administration confirming that a gas carrier complies with the IGC/GC Gas Code?

  • A. Certificate of Construction
  • B. Load Line Certificate
  • C. Safety Construction Certificate
  • D. International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk
Answer: D — International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk
The statutory document certifying full compliance with the International Gas Carrier Code regarding structure, containment, safety systems, and piping is the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk (COF).

7. Which space is defined as the space enclosed by the ship's structure in which a cargo containment system is situated?

  • A. Interbarrier space
  • B. Hold space
  • C. Void space
  • D. Cofferdam
Answer: B — Hold space
Under the IGC Code, a 'Hold Space' is the enclosed space bounded by the ship's primary hull structure within which a cargo containment system is located.

8. Which petroleum gases does commercial LPG mainly consist of?

  • A. Ethane & Pentane
  • B. Butadiene & Ammonia
  • C. Chlorine & Ethylene
  • D. Propane & Butane
Answer: D — Propane & Butane
Liquefied Petroleum Gas (LPG) consists predominantly of propane (C3H8), butane (C4H10), or mixtures of both hydrocarbons.

9. What is the primary purpose of inerting on a liquefied gas carrier?

  • A. To prevent flammable vapour/air mixtures in cargo tanks and associated piping
  • B. To increase oxygen content in vapour/air mixtures in tanks
  • C. To increase hydrocarbon concentration in vapour/air mixtures
  • D. To pressurize cargo tanks for deepwell pump suction
Answer: A — To prevent flammable vapour/air mixtures in cargo tanks and associated piping
The primary objective of inerting is to displace oxygen or flammable gas with an inert medium (such as nitrogen or flue gas) to ensure that the atmosphere in tanks and piping remains non-flammable at all times.

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