OCTCO/OCTF exit exam questions and answers — Set 4 — Oil and Chemical Tanker Cargo Operations
Set 4 of the Oil and Chemical Tanker Cargo Operations (OCTCO/OCTF) exit exam bank — 30 of 802 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.
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Set 4 — 30 OCTCO/OCTF exit exam questions with answers
1. What is very important to be carried out after use of deck foam system?
- A. Stop all pumps for deck foam system.
- B. Close all valves in the system.
- C. Flush the system complete with sea water.
- D. Clean the foam tank.
Answer: C — Flush the system complete with sea water.
After operating a deck foam firefighting system, the entire piping network must be thoroughly flushed with seawater/freshwater to prevent corrosive foam concentrate from hardening and clogging the pipes and monitors.
2. Fixed dry chemical powder extinguishers are mostly used in:
- A. Oil tankers.
- B. Passenger vessels.
- C. Chemical tankers.
- D. Bulk carriers.
Answer: C — Chemical tankers.
Fixed dry chemical powder (DCP) extinguishing systems are commonly installed on chemical tankers and gas carriers for rapid flame inhibition and three-dimensional gas/chemical fire knockdown.
3. During transit of a vessel if chemical fire occurs, the vessel should:
- A. Stop and allow other ships to proceed.
- B. Reduce vessel speed to minimum possible.
- C. Steer clear of other vessels.
- D. Anchor immediately.
Answer: C — Steer clear of other vessels.
If a chemical fire occurs on board a vessel during transit, the vessel should immediately alter heading to keep clear of other ships and position the wind to blow smoke away from the accommodation.
4. The electrostatic field strength which is sufficient to cause breakdown of air or petroleum gases is about?
- A. 5000 Kilovolts/meter
- B. 3000 Kilovolts/meter
- C. 3000 Volts/ meter
- D. 5000 Volts/meter
Answer: B — 3000 Kilovolts/meter
An electrostatic field strength of approximately 3,000 kilovolts per meter (3 kV/mm) is required to break down the dielectric strength of air or petroleum gas and cause an incendiary spark discharge.
5. A crew member is unconscious and the face is flushed. You should ___?
- A. Lay the crew member down with the head and shoulders slightly raised
- B. Administer a liquid stimulant
- C. Lay the crew member down with the head lower than the feet
- D. Attempt to stand the crew member upright to restore consciousness
Answer: A — Lay the crew member down with the head and shoulders slightly raised
For an unconscious casualty with a flushed (red) face, position them lying down with the head and shoulders slightly elevated to reduce cranial blood pressure.
6. What is the range of expansion ratio for high expansion foams?
- A. 1000: 1
- B. 5: 1 to 15: 1
- C. 1250 liters/ min
- D. 1000 liters/ min
Answer: A — 1000: 1
High-expansion foam systems produce foam with an expansion ratio typically up to 1000:1, allowing large enclosed spaces like engine rooms or pump rooms to be flooded quickly.
7. What is the least a person should do before entering machinery spaces?
- A. Wear appropriate personal protective equipment
- B. Inform the bridge
- C. Inform his superiors
- D. Check oxygen level
Answer: A — Wear appropriate personal protective equipment
Before entering machinery spaces, seafarers must always wear required personal protective equipment (PPE) including safety shoes, boiler suit, helmet, and ear defenders.
8. What is the least you must do before entering a cofferdam in the engine room?
- A. Open up the manhole and enter the cofferdam
- B. Complete an enclosed space checklist
- C. Enter the cofferdam and simultaneously start ventilation
- D. Check lighting only
Answer: B — Complete an enclosed space checklist
Before entering any cofferdam or enclosed compartment, a full enclosed space entry risk assessment and checklist (including multi-gas atmosphere testing) must be completed and signed by authorized officers.
9. TLV-STEL is the spot exposure of a chemical substance for a duration of:
- A. S minutes
- B. 15 minutes
- C. 30 minutes
- D. 60 minutes
Answer: B — 15 minutes
TLV-STEL (Threshold Limit Value - Short Term Exposure Limit) is the maximum concentration to which workers can be exposed continuously for a short period of 15 minutes without suffering adverse health effects.
10. What is pour point ?
- A. The temperature at which oil gets frozen
- B. The lowest temperature at which petroleum oil will remain fluid
- C. The temperature at which oil cannot be discharged
- D. The temperature at which oil needs to be heated
Answer: B — The lowest temperature at which petroleum oil will remain fluid
Pour point is defined as the lowest temperature at which a petroleum oil or liquid remains fluid and will pour or flow under standardized test conditions.
11. What is non-volatile petroleum?
- A. Petroleum having a flashpoint of 60 Degrees C or above
- B. Petroleum having a flashpoint of 60 Degrees C or below
- C. Petroleum having a flashpoint of 100 Degrees C or above
- D. Petroleum having a flashpoint of 100 Degrees C or below
Answer: A — Petroleum having a flashpoint of 60 Degrees C or above
Non-volatile petroleum is defined in ISGOTT as petroleum having a flashpoint of 60°C (140°F) or above.
12. What is the lower flammable limit?
- A. The concentration of a hydrocarbon gas in air below which there is insufficient hydrocarbon to support combustion
- B. The limit where there is insufficient oxygen to support combustion
- C. The limit where there is too much oxygen to support combustion
- D. The limit for man entry of personnel into tanks
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 hydrocarbon gas in air below which there is insufficient fuel to support combustion (the mixture is too lean).
13. What is cold work?
- A. Carrying out work in a cold atmosphere
- B. Work that cannot create a source of ignition
- C. Carrying out work on reefer containers
- D. Work that can be done only in cold temperatures
Answer: B — Work that cannot create a source of ignition
Cold work refers to maintenance, inspection, or repairs that do not involve heat, flames, or the potential generation of an ignition source or spark.
14. The most common measure taken on tankers to avoid static discharge is:
- A. Closed ullaging
- B. Use of only approved PPE on deck
- C. Bonding and grounding
- D. Having continuous pipe lengths.
Answer: C — Bonding and grounding
Static electrical accumulation and dangerous potential differences on tankers are avoided by bonding and grounding all pipes, hoses, and metal structures to the ship hull.
15. The permit towork should not last for more than?
- A. 12 hours
- B. 24 hours
- C. 36 hours
- D. 48 hours
Answer: B — 24 hours
A standard permit to work (PTW) for hot work or enclosed space entry is issued for a specific task and is valid for a maximum duration of 24 hours (or one work shift).
16. What is a hot work permit?
- A. Document used for carrying out repairs under super vision
- B. A document issued by the person responsible permitting specific hot work to be done during a particular time interval in a defined space
- C. Document used for work in a dry-dock
- D. Document valid for 7 days for carrying out tank cleaning
Answer: B — A document issued by the person responsible permitting specific hot work to be done during a particular time interval in a defined space
A hot work permit is a written safety document issued by an authorized responsible person permitting specific hot work within a designated space and timeframe following rigorous safety checks.
17. H2S gas is:
- A. Less toxic
- B. Inflammable
- C. Toxic, corrosive and flammable
- D. Non-toxic
Answer: C — Toxic, corrosive and flammable
Hydrogen sulphide (H2S) is a highly toxic, corrosive, and flammable gas with a characteristic rotten-egg odor at low concentrations.
18. Electrons have:
- A. No charge
- B. Positive charge
- C. Negative charge
- D. Neutral charge
Answer: C — Negative charge
Electrons are subatomic particles carrying a negative electric charge.
19. How to reduce Hydrogen Sulphide Hazard in Residual Fuel Oils?
- A. Ventilation to lower the concentration of vapor in the ullage space and in specific areas where vapors may accumulate should be carried out as soon as practicable.
- B. Transfer the oil to some other tank using fuel transfer pump,
- C. Keep heating the oil to maintain a higher temperature
- D. Circulate the oil in the same tank using the cargo pump
Answer: A — Ventilation to lower the concentration of vapor in the ullage space and in specific areas where vapors may accumulate should be carried out as soon as practicable.
H2S hazards in residual fuel tanks are mitigated by ventilating ullage spaces to disperse accumulated toxic vapours as soon as practicable prior to sampling, gauging, or tank work.
20. Inert gas is introduced to cargo tank to:
- A. Lower the LEL of cargo vapor.
- B. To make the cargo vapors a lean mixture of hydro carbons
- C. To exclude oxygen and thus prevent fire or explosion.
- D. Cool down the cargo
Answer: C — To exclude oxygen and thus prevent fire or explosion.
Inert gas (with low oxygen content <5% from the generator and <8% in the tank) is supplied to cargo tanks to displace oxygen and render the atmosphere non-flammable.
21. What is Cargo inhibition?
- A. All chemical cargo physical and chemical properties change. during transportation; to avoid this, certain inhibitors are added to the cargo
- B. For some chemical cargoes. under heat and in presence of oxygen, their physical and Chemical properties change. To avoid this certain inhibitor are added to the cargo
- C. Some chemical cargoes have some physical and chemical properties that change due to cold weather in presence of oxygen, to avoid this. Certain inhibitors are added to the cargo
- D. Adding Inhibitors to a refined vegetable oil adds its market value as the inhibitor maintains its color
Answer: B — For some chemical cargoes. under heat and in presence of oxygen, their physical and Chemical properties change. To avoid this certain inhibitor are added to the cargo
Cargo inhibition involves adding specific chemical stabilizers/inhibitors to sensitive monomers (like styrene) to prevent self-polymerization or degradation under temperature and oxygen exposure.
22. Why are inhibitors added in the cargo?
- A. Inhibitors are added by the ship staff before loading are Toxic. Inhibited cargoes often need oxygen hence should be carried in inerted tanks.
- B. Inhibitors are added by the Terminal before loading are Toxic. Inhibited cargoes often need oxygen hence should not be carried in inerted tanks.
- C. Inhibitors that are added by the Terminal before loading are Non-Toxic. Inhibited cargoes do not need oxygen and can be carried in inerted tanks.
- D. Once the cargo is inhibited, its temperature is never a concern for cargo carriage
Answer: B — Inhibitors are added by the Terminal before loading are Toxic. Inhibited cargoes often need oxygen hence should not be carried in inerted tanks.
Certain chemical cargo inhibitors require dissolved oxygen to remain active; carrying these inhibited cargoes under total inerting without proper oxygen levels can cause premature inhibitor failure.
23. The main elements of peak safety performance are?
- A. reducing the number of accidents to less than 5 % of the previous year's accidents
- B. reducing the number of pollution incidents to less than 2 % of the previous year pollution incidents.
- C. No operational incidents, no personal injuries and no harm to the environment.
- D. Increasing vessel speed
Answer: C — No operational incidents, no personal injuries and no harm to the environment.
Peak safety performance in modern shipping targets zero operational incidents, zero occupational personal injuries, and zero environmental pollution.
24. Organizational safety value aims at:
- A. < 2 incidents in a year
- B. reduce incidents to less than 10 % of incidents in the previous year
- C. Zero incident program
- D. allow only one incident per year.
Answer: C — Zero incident program
A proactive organizational safety culture aims for continuous safety excellence through a zero-incident program.
25. What factor mainly affects Vapor cloud dilution rate?
- A. Quantity of Spill
- B. Weather conditions
- C. Thermal inversion
- D. diameter of the vapor cloud
Answer: B — Weather conditions
The rate of dispersion and dilution of a hazardous vapour cloud in the atmosphere is primarily governed by prevailing ambient weather conditions (wind speed, turbulence, atmospheric stability).
26. How is the Putrefaction process connected to Carbon Monoxide?
- A. Putrefaction process generates obnoxious and toxic vapors
- B. Putrefaction process depletes the oxygen in the tank due to chemical reaction
- C. Putrefaction process generates obnoxious and toxic vapors and these depletes the oxygen in the tank due to chemical react ion
- D. Purification occurs due to a decrease in tank temperature
Answer: B — Putrefaction process depletes the oxygen in the tank due to chemical reaction
Putrefaction of organic materials or vegetable oils depletes oxygen in the enclosed space through chemical decomposition and generates hazardous toxic gases.
27. Chemical cargo vapors can enter the human body due to:
- A. Continuous working on deck.
- B. Working i n the pump room
- C. Inhalation, skin contact and also swallowing.
- D. Improper use of proper PPE
Answer: C — Inhalation, skin contact and also swallowing.
Chemical cargo vapours and toxins can enter the human body via three primary exposure pathways: inhalation (respiratory tract), skin contact/absorption, and ingestion (swallowing).
28. Key Features and Measurement of an Effective Safety Culture; identify one statement that identifies an effective safety culture?
- A. Recognition that all accidents are preventable and only usually occur following unsafe actions or a failure to follow established procedures
- B. Individual seafarers assume responsibility for safety rather than relying on others to provide it
- C. Through mutual respect, increasing confidence in the value of the safety culture results in a more effective Safety Management System
- D. A safety management system that is always setting targets for continuous improvement, with a goal of zero accidents
Answer: D — A safety management system that is always setting targets for continuous improvement, with a goal of zero accidents
A core principle of an effective safety culture is the continuous drive of the safety management system toward continuous improvement with the ultimate goal of zero accidents.
29. Paraffinic, Paraffinic- Naphthenic and Aromatic Intermediate are the three classifications of?
- A. Natural gas
- B. Crude oil
- C. Coal
- D. Asphalt
Answer: B — Crude oil
Crude oils are broadly classified based on chemical composition into paraffinic, paraffinic-naphthenic, and aromatic/asphaltic intermediate bases.
30. Higher viscosity means?
- A. Proper atomization of fuel
- B. Rich atomization of fuel
- C. Poor atomization of fuel
- D. Easy pumping
Answer: C — Poor atomization of fuel
Higher viscosity fluids resist atomization and flow, leading to poor atomization and incomplete combustion in oil-burning systems unless preheated.
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