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OCTCO/OCTF exit exam questions and answers — Set 10 — Oil and Chemical Tanker Cargo Operations

Set 10 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 10 — 30 OCTCO/OCTF exit exam questions with answers

1. Which statement is correct concerning the starting of centrifugal pumps?

  • A. They should always be started with the discharge valve open
  • B. They should always be started with the sealing line valves closed
  • C. A priming pump is always required to flood the impeller suction
  • D. They should normally be started with the discharge valve closed
Answer: D — They should normally be started with the discharge valve closed
A centrifugal pump draws minimum power at zero flow, so starting with the discharge valve closed limits the starting current and prevents pressure surges. The valve is then opened gradually once the pump has built up pressure.

2. Before gas freeing, the hydrocarbon content of an inerted cargo tank should be reduced by purging to below ____ by volume.

  • A. 8%
  • B. 11%
  • C. 5%
  • D. 2%
Answer: D — 2%
ISGOTT requires inerted tanks to be purged with inert gas until the hydrocarbon content is below 2% by volume before introducing air. This ensures that the mixture will not pass through the flammable range as air dilutes the inert gas.

3. In oil tankers, continuous oxygen analysers for the inert gas system are fitted ____.

  • A. Permanently
  • B. Temporarily
  • C. As portable units
  • D. Only during cargo discharge
Answer: A — Permanently
The FSS Code (Chapter 15) requires inert gas systems to have permanently fitted instruments that continuously indicate and record the oxygen content and pressure of the inert gas supplied, with alarms on high oxygen.

4. The internal space in the lower part of a ship's hold or engine room into which accumulated water drains and from which it is pumped is called the:

  • A. Drain tank
  • B. Pit well
  • C. Bilge
  • D. Bilge tank
Answer: C — Bilge
The bilges are the lowest internal spaces of the hull where water, oil and leakage collect. Bilge wells and suctions connected to the bilge pumping system allow this water to be removed, as required by SOLAS II-1.

5. The main inert gas distribution line on deck is provided with one or more ____.

  • A. Gauge glasses to monitor the presence of liquid
  • B. Flow meters
  • C. Pressure/vacuum (PV) breakers
  • D. Fixed oxygen content analysers
Answer: C — Pressure/vacuum (PV) breakers
The FSS Code requires one or more pressure/vacuum breaking devices on the inert gas main to protect cargo tanks against excessive pressure or vacuum if the P/V valves fail or the inert gas system cannot keep up with cargo rates.

6. While discharging cargo, the oxygen content in the inert gas main rises above the SOLAS limit and the engine room informs you that they cannot reduce it. What should you do?

  • A. Continue with cargo operations
  • B. Call the Chief Engineer and continue with cargo operations
  • C. Stop all cargo operations
  • D. Call the Master and continue with cargo operations
Answer: C — Stop all cargo operations
SOLAS and the FSS Code require cargo tank atmospheres to be kept at no more than 8% oxygen by volume. If inert gas of acceptable quality cannot be supplied, discharge must be stopped so that air is not drawn into the tanks.

7. If information concerning a cargo is not available, the cargo should be ____.

  • A. Not loaded
  • B. Loaded
  • C. Loaded until the information becomes available
  • D. Loaded with caution
Answer: A — Not loaded
Without full cargo information, such as the safety data sheet and the cargo's hazards and handling requirements, the ship cannot assess compatibility, ventilation, firefighting and personnel protection, so the cargo must not be accepted.

8. When discharging a tanker, how can list be controlled?

  • A. By shore-side personnel
  • B. By using the afterpeak tank, loading as necessary
  • C. By using a wing tank near the longitudinal centre, discharging as necessary
  • D. By using a centre tank near the bow, discharging as necessary
Answer: C — By using a wing tank near the longitudinal centre, discharging as necessary
List is caused by a transverse imbalance of weight. Adjusting the discharge from wing tanks near amidships corrects the list most effectively, with minimal effect on trim, while centre tanks have little transverse effect.

9. Which valve goes from fully open to fully closed when its handle is turned through 90°?

  • A. Butterfly valve
  • B. Check valve
  • C. Globe stop valve
  • D. Gate valve
Answer: A — Butterfly valve
A butterfly valve has a disc that rotates on a spindle across the pipe bore, so a quarter turn moves it from fully open to fully closed. Gate and globe valves require many turns of the handwheel, and check valves are not manually operated.

10. Compressed air cylinders of breathing apparatus sets should be pressure tested ashore at intervals not exceeding ____.

  • A. 10 years
  • B. 6 years
  • C. 5 years
  • D. 15 years
Answer: C — 5 years
IMO guidance on maintenance and inspection of fire protection systems (MSC.1/Circ.1432) requires breathing apparatus air cylinders to be hydrostatically tested at intervals not exceeding five years, or as required by the manufacturer.

11. The time allowed in the charter party for loading or discharging cargo is called:

  • A. Laytime
  • B. Specified loading time
  • C. Maximum allowed loading time
  • D. Charter party loading time
Answer: A — Laytime
Laytime is the period agreed in a voyage charter party for the charterer to load and discharge cargo without paying extra. Time used beyond laytime is charged as demurrage, while time saved may earn despatch.

12. During cargo operations, or whenever dangerous vapour may be present on deck, you should:

  • A. Keep accommodation doors and windows open to allow vapour to dissipate
  • B. Immediately cease all cargo operations
  • C. Hoist flag Bravo
  • D. Keep closed all ports and windows facing the cargo area
Answer: D — Keep closed all ports and windows facing the cargo area
ISGOTT requires external doors, ports and windows of the accommodation facing or near the cargo area to be kept closed during cargo operations, so that flammable or toxic vapour cannot enter the accommodation where ignition sources exist.

13. Any hawser by which a vessel is secured to a dock or mooring, made of natural fibre, synthetic fibre or wire, is called a:

  • A. Breast line
  • B. Spring line
  • C. Heaving line
  • D. Mooring line
Answer: D — Mooring line
Mooring line is the general term for any rope or wire used to secure a ship to a berth, buoy or another vessel. Head, stern, breast and spring lines are particular mooring lines named by their direction of lead.

14. Temperature control of cargoes means ____.

  • A. Applying heat in a controlled manner
  • B. Allowing the cargo to adopt ambient temperature
  • C. Allowing the cargo to heat naturally
  • D. Merely monitoring the cargo temperature
Answer: A — Applying heat in a controlled manner
Cargoes such as heavy fuel oils, vegetable oils and certain chemicals must be kept within specified temperature limits. Heating coils are used to apply heat in a controlled manner to maintain pumpability without damaging the cargo.

15. The narrow empty space between two adjacent watertight or oiltight compartments, designed to isolate them from each other, is called a ____.

  • A. Void tank
  • B. Buoyancy tank
  • C. Reserve fuel tank
  • D. Cofferdam
Answer: D — Cofferdam
A cofferdam is a narrow void space separating two compartments, such as cargo tanks from the engine room or fuel tanks from fresh water tanks, so that leakage from one cannot directly contaminate the other. SOLAS and MARPOL require them in specified locations.

16. How should pinching of the cargo hose between the vessel and the dock be prevented?

  • A. Tying the topping lifts and runners to the winch heads
  • B. Laying out an excess length of hose on deck
  • C. Adjusting the hose supports
  • D. Lashing the hose tightly to the ship's rail
Answer: C — Adjusting the hose supports
Cargo hoses must be properly supported by saddles or slings so they are not pinched, kinked or chafed between the ship's side and the jetty. Hose supports are adjusted as the vessel rises or falls with tide and draught changes.

17. Which MARPOL Annex governs the international carriage of chemical cargoes in bulk?

  • A. Annex V
  • B. Annex II
  • C. Annex III
  • D. Annex I
Answer: B — Annex II
MARPOL Annex II contains the regulations for the control of pollution by noxious liquid substances carried in bulk, which covers bulk chemical cargoes. Annex I covers oil, Annex III packaged harmful substances and Annex V garbage.

18. Entry into a cargo tank can be made when the atmosphere is ____.

  • A. HC more than 1% LFL / O2 21% / CO 1 ppm / H2S 3 ppm
  • B. HC less than 1% LFL / O2 21% / CO 50 ppm / H2S 1 ppm
  • C. HC less than 1% LFL / O2 18% / CO 50 ppm / H2S 1 ppm
  • D. HC less than 1% LFL / O2 21% / CO 0 ppm / H2S 0 ppm
Answer: D — HC less than 1% LFL / O2 21% / CO 0 ppm / H2S 0 ppm
ISGOTT requires that before entry the space be ventilated to 21% oxygen by volume, hydrocarbon below 1% LFL and toxic gases such as CO and H2S below their occupational exposure limits, ideally not detectable. Oxygen at 18% or CO at 50 ppm is unacceptable.

19. Which of the following valves should be used only in either the fully open or the fully closed position?

  • A. Any needle valve
  • B. Any check valve
  • C. A globe valve
  • D. A gate valve
Answer: D — A gate valve
A gate valve is designed for isolation only. Used partially open, the gate vibrates and the seats and wedge are eroded by high-velocity flow, so it should be either fully open or fully closed. Globe and needle valves are used for throttling.

20. Cryogenic burns can result in frostbite. What is the proper immediate treatment?

  • A. Massage the affected area
  • B. Apply ice to the area and gradually warm
  • C. Warm the area quickly by immersing in water at about 108°F (42°C) until thawed
  • D. Compress the affected area with a cryogenic burn heat wrap
Answer: C — Warm the area quickly by immersing in water at about 108°F (42°C) until thawed
Frostbite from cryogenic liquid contact is treated by rapid rewarming of the affected part in warm water at about 40 to 42°C (104 to 108°F). Rubbing or massaging damages frozen tissue, and applying ice worsens the injury.

21. What is the requirement for the diameter of the crude oil washing lines?

  • A. It must maintain the pressure only
  • B. It must maintain the flow only
  • C. There is no special requirement for the line dimension
  • D. It must maintain the required pressure and flow for the type of tank cleaning machine in use
Answer: D — It must maintain the required pressure and flow for the type of tank cleaning machine in use
COW supply lines are sized so that the pressure and flow rate delivered to each machine meet the machine manufacturer's requirements when the designed number of machines operate simultaneously, as stated in the approved COW Operations and Equipment Manual.

22. Which conditions must exist for an electrostatic spark discharge to occur?

  • A. Charge separation
  • B. Charge accumulation
  • C. An electrostatic discharge path (spark gap)
  • D. All of the above
Answer: D — All of the above
ISGOTT lists three stages for a static ignition hazard: charge separation, charge accumulation on an insulated object or liquid, and a discharge of sufficient energy across a gap. All three must occur in a flammable atmosphere for ignition.

23. The prime mover of a deepwell cargo pump is usually a(n) ____ motor.

  • A. Electric
  • B. Pneumatic
  • C. Steam
  • D. Electric or hydraulic
Answer: D — Electric or hydraulic
Deepwell cargo pumps on product and chemical tankers are driven from deck by either an electric motor (with a gas-tight bulkhead or on deck) or a hydraulic motor, depending on the design. Steam and pneumatic drives are not normally used.

24. How is sea water supplied to the inert gas deck seal?

  • A. Through the deck fire line
  • B. Through the main sea water pump or the cargo condenser pump
  • C. Through the deck seal pump fitted in the engine room
  • D. Through a sea water pump fixed on the cargo deck
Answer: C — Through the deck seal pump fitted in the engine room
The deck water seal is supplied by dedicated deck seal pumps, normally located in the engine room, with a standby pump or alternative supply. The supply must be maintained at all times, including when the IG plant is shut down.

25. Which statement is correct regarding the operation of an eductor?

  • A. Suction pressure must be checked continuously
  • B. It must be operated according to the specific eductor's performance curve
  • C. It requires a minimum 8 bar drive pressure and high back pressure
  • D. It requires a minimum 12 bar drive pressure
Answer: B — It must be operated according to the specific eductor's performance curve
Eductor performance depends on drive pressure, suction head and back pressure, and each eductor has its own performance curve. It should be operated within that curve; high back pressure reduces or stops suction.

26. What is meant by dirty ballast?

  • A. Ballast water contaminated with mud
  • B. Sea water used as ballast that is contaminated with residues of crude oil or persistent refined oils left in cargo tanks
  • C. Ballast water from a different origin
  • D. Ballast carried in dedicated segregated ballast tanks
Answer: B — Sea water used as ballast that is contaminated with residues of crude oil or persistent refined oils left in cargo tanks
Dirty ballast is ballast water carried in cargo tanks that previously carried oil and is therefore contaminated with oil residues. It must be discharged only in accordance with MARPOL Annex I or to reception facilities.

27. Which document states the minimum freeboard assigned to a vessel and the position of the load line mark on the ship's side?

  • A. International Load Line Certificate
  • B. International Tonnage Certificate
  • C. Safety Construction Certificate
  • D. Certificate of Registry
Answer: A — International Load Line Certificate
The International Load Line Certificate, issued under the Load Line Convention 1966 by the Administration or a recognised organisation on its behalf, records the assigned freeboards and the position of the deck line and load line disc.

28. Under MARPOL Annex II, noxious liquid substances that present a major hazard to marine resources or human health, justifying prohibition of discharge into the sea, are classed as Category ____.

  • A. X
  • B. Y
  • C. Z
  • D. OS (Other Substances)
Answer: A — X
MARPOL Annex II Reg 6 places NLS in Category X when discharge from tank cleaning or deballasting presents a major hazard, so discharge is prohibited. Category Y is a hazard with limits, Z a minor hazard, and OS no harm.

29. A gauging system that allows no cargo vapour to escape to the atmosphere is called a ____ gauging system.

  • A. Closed
  • B. Restricted
  • C. Open
  • D. Partially closed
Answer: A — Closed
A closed gauging system, such as radar or float gauges, measures ullage without releasing vapour and is used extensively on inerted tankers. Systems that release a small amount of vapour, such as sounding pipes with vapour locks, are called restricted systems.

30. Hazards associated with dangerous liquid substances include ____.

  • A. Flammability
  • B. Corrosivity
  • C. Toxicity
  • D. All of the above
Answer: D — All of the above
Dangerous liquid cargoes, especially chemicals, may present flammability, toxicity, corrosivity and reactivity hazards, which are listed for each product in the IBC Code and cargo safety data sheets. A single cargo often presents several of these hazards.

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