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OCTCO/OCTF exit exam questions and answers — Set 14 — Oil and Chemical Tanker Cargo Operations

Set 14 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.

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 14 — 30 OCTCO/OCTF exit exam questions with answers

1. What do you understand by the term 'bleed-off COW'?

  • A. The process of pressure testing the COW lines on board
  • B. Diverting part of the cargo discharged to reduce the discharge rate
  • C. Diverting part of the cargo discharged for crude oil washing
  • D. Draining oil from the COW lines after washing
Answer: C — Diverting part of the cargo discharged for crude oil washing
In bleed-off crude oil washing, part of the discharge from a main cargo pump is diverted into the COW line to supply the tank washing machines, while the remainder continues ashore.

2. The product of the coefficient of viscosity, surface area and velocity gradient between layers of a flowing liquid is the

  • A. Viscosity of the liquid
  • B. Force of friction between liquid layers
  • C. Velocity of the fluid
  • D. Vapour pressure of the liquid
Answer: B — Force of friction between liquid layers
By Newton's law of viscosity, the shear (viscous friction) force between adjacent layers equals the coefficient of viscosity multiplied by the contact area and the velocity gradient between the layers.

3. Of the hydrocarbons found in nature, which is the lighter fraction that can exist free or dissolved in crude oil?

  • A. Crude oil
  • B. Natural gas
  • C. Asphalt
  • D. Refined oil
Answer: B — Natural gas
Natural gas, mainly methane with some ethane, propane and butane, is the lightest hydrocarbon fraction in reservoirs. It occurs as free gas above the oil or dissolved in the crude under pressure.

4. Pyrophoric oxidation is associated with carrying

  • A. Light crude oils
  • B. Sour crude oils
  • C. Refined products
  • D. Chemical cargoes
Answer: B — Sour crude oils
Sour crudes contain hydrogen sulphide, which reacts with tank rust in an oxygen-deficient atmosphere to form iron sulphide. When exposed to air this iron sulphide oxidises rapidly and can glow, providing an ignition source.

5. The emergency plan for a ship will be influenced by a number of factors. Which one will have the largest impact?

  • A. Risk assessment of the ship type and cargo
  • B. Known accidents and incidents in shipping and on company vessels
  • C. Experience and expertise of the master
  • D. Experience and expertise of shipboard personnel and shore management
Answer: A — Risk assessment of the ship type and cargo
Under the ISM Code, emergency preparedness is based on identifying potential emergency situations. The ship type, age, design and the hazards of the cargo carried determine which emergencies are credible and therefore shape the plan most.

6. The MFAG (Medical First Aid Guide for Use in Accidents Involving Dangerous Goods) is published by the

  • A. International Maritime Organization
  • B. World Health Organization
  • C. United Nations
  • D. International Labour Organization
Answer: A — International Maritime Organization
The MFAG is an IMO publication, issued as part of the IMDG Code supplement and developed jointly with WHO and ILO. It gives first-aid guidance for chemical poisoning on board.

7. A shipboard oil pollution emergency plan is required for

  • A. All vessels, regardless of size and commercial application
  • B. Any ship constructed or operated so that no oil in any form can be carried on board
  • C. Oil tankers of 150 GT and above, and other ships of 400 GT and above
  • D. Oil tankers of 400 GT and above, and other ships of 150 GT and above
Answer: C — Oil tankers of 150 GT and above, and other ships of 400 GT and above
MARPOL Annex I Regulation 37 requires every oil tanker of 150 gross tonnage and above and every other ship of 400 gross tonnage and above to carry an approved Shipboard Oil Pollution Emergency Plan.

8. Inert gas systems must be capable of maintaining an oxygen content by volume in the cargo tanks of not more than

  • A. 2%
  • B. 8%
  • C. 5%
  • D. 11%
Answer: B — 8%
SOLAS II-2 and the FSS Code Chapter 15 require the IGS to maintain the atmosphere in any part of a cargo tank at not more than 8% oxygen by volume, while the gas delivered by the plant should not exceed 5%.

9. The ISM Code requires work procedures which ensure ____ performance.

  • A. Superior
  • B. Safe
  • C. Profitable
  • D. Excellent
Answer: B — Safe
The ISM Code objectives are safety at sea, prevention of injury or loss of life and avoidance of environmental damage. Companies must establish procedures and instructions ensuring safe operation of ships and protection of the environment.

10. Oily cargo residues may be discharged from an oil tanker at an instantaneous rate not exceeding how many litres per nautical mile, provided all other conditions are met?

  • A. 10
  • B. 30
  • C. 20
  • D. 21
Answer: B — 30
MARPOL Annex I Regulation 34 permits discharge from the cargo area of an oil tanker only when en route, more than 50 NM from land, outside special areas, with the instantaneous rate of discharge not exceeding 30 litres per nautical mile.

11. What type of crude oil is used for crude oil washing?

  • A. Dry
  • B. Wet
  • C. Both dry and wet
  • D. Sweet only
Answer: A — Dry
Only dry crude, free of settled water, should be used for COW. Water in the washing oil can generate electrostatic charge in the mist during washing and reduces cleaning effectiveness, so the source tank is decanted first.

12. An explosimeter is used for measuring the percentage of

  • A. UFL
  • B. LEL
  • C. Inert gas
  • D. Oxygen
Answer: B — LEL
An explosimeter (catalytic combustible gas indicator) is calibrated to read hydrocarbon concentration as a percentage of the lower explosive limit, from 0 to 100% LEL. It does not measure oxygen or inert gas.

13. Purging is the introduction of which gas into an already inerted tank?

  • A. Oxygen
  • B. Inert gas
  • C. Air
  • D. Steam
Answer: B — Inert gas
ISGOTT defines purging as introducing inert gas into a tank already in the inert condition to further reduce the oxygen and hydrocarbon content, so that air can later be admitted without the atmosphere passing through the flammable range.

14. All equipment used on tankers, such as walkie-talkies, torches and cameras, must be

  • A. Sturdy
  • B. Made of brass
  • C. Intrinsically safe
  • D. Of good quality
Answer: C — Intrinsically safe
Portable electrical equipment used in the cargo area or hazardous zones of a tanker must be of an intrinsically safe, certified type, so that any spark or heat it produces cannot ignite flammable vapours.

15. The percentage of oxygen in the atmosphere is

  • A. 15%
  • B. 21%
  • C. 20%
  • D. 24%
Answer: B — 21%
Normal air contains about 21% oxygen by volume, the rest being mainly nitrogen. Before entry, an enclosed space must show a steady 21% oxygen reading to be considered safe from oxygen deficiency.

16. The resistance of a liquid to flow is called

  • A. Pressure surge
  • B. Viscosity
  • C. Mobility
  • D. Hydraulic pressure
Answer: B — Viscosity
Viscosity is the internal friction of a fluid which resists flow. High-viscosity cargoes need heating to be pumped efficiently, and viscosity decreases as temperature rises.

17. Various properties of a chemical cargo include

  • A. Melting point
  • B. Volatility
  • C. Vapour pressure
  • D. All of the above
Answer: D — All of the above
Physical properties such as melting point, volatility and vapour pressure, listed in the cargo data sheet, determine heating requirements, venting, vapour hazards and handling precautions for chemical cargoes.

18. Cargo quantity is calculated at what temperature?

  • A. Ambient temperature
  • B. Local average temperature
  • C. Standard temperature
  • D. Highest recorded temperature
Answer: C — Standard temperature
Because oil volume varies with temperature, observed volumes are corrected to a standard temperature, normally 15°C (or 60°F), using ASTM petroleum measurement tables, so that quantities can be compared consistently.

19. Pump room ventilation ____ be kept running while personnel are working in the pump room.

  • A. May
  • B. May not
  • C. Must
  • D. Need not
Answer: C — Must
ISGOTT requires cargo pump rooms to be mechanically ventilated before entry and continuously while anyone is inside, to remove heavier-than-air hydrocarbon or toxic vapours from leaks and to maintain a safe atmosphere.

20. How many cargo pumps are normally fitted inside one cargo tank on a chemical tanker?

  • A. One
  • B. Two
  • C. Three
  • D. None
Answer: A — One
Modern chemical tankers normally have one deepwell or submerged pump in each cargo tank, allowing each tank to be discharged independently and giving full segregation of different chemical grades.

21. The minimum percentage of oxygen required to support combustion of hydrocarbon gas is about

  • A. 0.5%
  • B. 18%
  • C. 11%
  • D. 21%
Answer: C — 11%
ISGOTT notes that hydrocarbon gas mixtures cannot burn when the oxygen content is below about 11% by volume. This is why IG systems keep tank oxygen at 8% or less, giving a safety margin.

22. The fire triangle consists of

  • A. Oxygen
  • B. Flammable material
  • C. Ignition source
  • D. All of the above
Answer: D — All of the above
Fire requires fuel, oxygen and a source of ignition (heat). Removing any one side of the triangle prevents or extinguishes a fire, which is the basis of tanker fire prevention through inerting and ignition control.

23. A sudden increase of liquid pressure in a pipeline is called

  • A. Pressure drop
  • B. Pressure value
  • C. Pressure surge
  • D. All of the above
Answer: C — Pressure surge
A pressure surge occurs when liquid flow is suddenly stopped, for example by rapid valve closure. The kinetic energy is converted to a pressure wave that can rupture hoses, loading arms or pipelines.

24. MARPOL Annex II deals with

  • A. Oil pollution
  • B. Pollution by noxious liquid substances (chemicals) in bulk
  • C. Both oil and chemical pollution
  • D. Sewage pollution
Answer: B — Pollution by noxious liquid substances (chemicals) in bulk
MARPOL Annex II contains regulations for the control of pollution by noxious liquid substances carried in bulk, which covers chemical tankers, categories X, Y, Z and OS, and the Cargo Record Book.

25. Lifeboats should be equipped with

  • A. 2 buoyant rescue quoits attached to not less than 30 m of buoyant line
  • B. 2 buoyant rescue quoits attached to not less than 15 m of buoyant line
  • C. 1 buoyant rescue quoit attached to not less than 30 m of buoyant line
  • D. 1 buoyant rescue quoit attached to not less than 15 m of buoyant line
Answer: A — 2 buoyant rescue quoits attached to not less than 30 m of buoyant line
LSA Code 4.4.8 lists the normal lifeboat equipment, which includes two buoyant rescue quoits, each attached to not less than 30 m of buoyant line.

26. What is a deadweight scale?

  • A. The maximum deadweight the vessel can achieve
  • B. The ratio of deadweight and reserve buoyancy
  • C. The maximum reserve buoyancy the vessel can have
  • D. A table forming part of the ship's plans showing the draught for a given deadweight or displacement
Answer: D — A table forming part of the ship's plans showing the draught for a given deadweight or displacement
A deadweight scale is a diagram or table supplied with the ship's plans giving, against draught, the corresponding deadweight, displacement, TPC and freeboard, so the draught for a given load can be read off.

27. In a fire emergency, the duties of the technical (engine) team include

  • A. Informing the office about the fire
  • B. Starting the fire pump and emergency generator
  • C. Maintaining communication with the bridge team
  • D. Both starting the fire pump and emergency generator and maintaining communication with the bridge
Answer: D — Both starting the fire pump and emergency generator and maintaining communication with the bridge
The engine team supports fire fighting by starting fire pumps and the emergency generator and keeping communication with the bridge command. Informing the office is a duty of the master and bridge team.

28. Where inert gas supply to individual cargo tanks can be isolated, the isolating valves must be provided with means for

  • A. Draining inert gas
  • B. Fitting blind or spectacle flanges
  • C. Securing and locking in the closed position
  • D. Easy removal and inspection
Answer: C — Securing and locking in the closed position
Where individual tanks can be isolated from the IG main, the FSS Code requires the isolating valves to have locking arrangements under the control of a responsible officer, preventing accidental isolation of a tank from inert gas.

29. Hot work at a tanker berth should not be carried out until permission is obtained from

  • A. The master
  • B. The chief officer
  • C. The company safety officer
  • D. The terminal representative
Answer: D — The terminal representative
ISGOTT states that hot work on a tanker alongside a terminal is prohibited unless authorised by the terminal (and port authority where required), in addition to the ship's own permit to work system.

30. The fire control plan must be permanently exhibited on board, and a duplicate set must also be available elsewhere. Where must this duplicate be kept?

  • A. In the engine control room
  • B. At the terminal
  • C. In a weathertight enclosure near the gangway
  • D. Handed over to the surveyor
Answer: C — In a weathertight enclosure near the gangway
SOLAS II-2/15.2.4 requires a duplicate set of fire control plans to be kept permanently in a prominently marked weathertight enclosure outside the deckhouse, normally near the gangway, for the assistance of shore fire-fighting personnel.

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