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OCTCO/OCTF exit exam questions and answers — Set 1

Set 1 of the Oil and Chemical Tanker Cargo Operations (OCTCO/OCTF) exit exam bank — 30 of 252 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 1 — 30 OCTCO/OCTF exit exam questions with answers

1. What MARPOL Annex regulates prevention of oil pollution from tankers?

  • A. MARPOL Annex I
  • B. MARPOL Annex II
  • C. MARPOL Annex V
  • D. MARPOL Annex III
Answer: A — MARPOL Annex I
MARPOL Annex I contains regulations for preventing oil pollution.

2. What is the maximum oxygen content allowed in inert gas supplied to cargo tanks?

  • A. 21%
  • B. 5% by volume (max 8% inside tanks)
  • C. 0%
  • D. 15%
Answer: B — 5% by volume (max 8% inside tanks)
Inert Gas Systems supply IG with O2 < 5%; tank atmosphere must be < 8% O2.

3. What operation uses crude oil jets to clean sludges from tank walls during discharge?

  • A. Crude Oil Washing (COW)
  • B. Water flushing
  • C. Steam cleaning
  • D. Solvent soaking
Answer: A — Crude Oil Washing (COW)
COW uses crude oil jets to dissolve waxy sludges during discharge.

4. What condition is mandatory before starting Crude Oil Washing (COW)?

  • A. Boiler off
  • B. Tank open to air
  • C. Dry dock
  • D. Cargo tank must be inerted with O2 < 8%
Answer: D — Cargo tank must be inerted with O2 < 8%
COW generates static charges; tank O2 must be below 8% to prevent explosion.

5. What system monitors and controls oily water discharge overboard from slop tanks?

  • A. Salinometer
  • B. OWS 15 ppm alarm
  • C. Echo sounder
  • D. Oil Discharge Monitoring and Control System (ODMCS)
Answer: D — Oil Discharge Monitoring and Control System (ODMCS)
ODMCS logs oil content, discharge rate (L/nm), and total oil discharged.

6. What is the maximum instantaneous rate of oil discharge allowed outside Special Areas under MARPOL Annex I?

  • A. 100 L/nm
  • B. Zero
  • C. 30 liters per nautical mile
  • D. 15 ppm
Answer: C — 30 liters per nautical mile
MARPOL Annex I limits en-route oil discharge to 30 L/nm.

7. What device stops hydrocarbon gas backflowing from cargo tanks into the machinery space?

  • A. Butterfly valve
  • B. Deck Water Seal and Non-Return Valve
  • C. Fan
  • D. Flame screen
Answer: B — Deck Water Seal and Non-Return Valve
The deck water seal provides a water barrier stopping gas backflow to engine room.

8. What instrument measures flammable vapor concentration as a percentage of LEL?

  • A. Explosimeter (Combustible Gas Indicator)
  • B. Dip tube
  • C. Oxygen Analyzer
  • D. Refractometer
Answer: A — Explosimeter (Combustible Gas Indicator)
Explosimeters measure flammable gas concentration up to 100% LEL.

9. What is Reid Vapor Pressure (RVP)?

  • A. Standard measure of crude oil vapor pressure at 100°F (37.8°C)
  • B. Air pressure
  • C. Hydraulic pressure
  • D. Steam pressure
Answer: A — Standard measure of crude oil vapor pressure at 100°F (37.8°C)
RVP indicates oil volatility and vapor evolution tendency.

10. What device protects oil cargo tanks against overpressure or vacuum structural damage?

  • A. High-velocity Pressure/Vacuum (P/V) valve
  • B. Gate valve
  • C. Quick closing valve
  • D. Storm valve
Answer: A — High-velocity Pressure/Vacuum (P/V) valve
P/V valves automatically relieve overpressure or vacuum inside tanks.

11. Under STCW Code Table A-V/1-1-1, what is the mandatory requirement regarding regulatory compliance and STCW code requirements during Basic Oil & Chemical Tanker operations?

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

12. What specific safety precaution must be observed when managing regulatory compliance and STCW code requirements for Basic Oil & Chemical Tanker on board?

  • A. Proceeding without informing the officer on watch
  • B. Conducting a thorough risk assessment and briefing all involved personnel prior to starting work
  • C. Disabling automated safety alarms to save time
  • D. Delegating tasks exclusively to untrained crew members
Answer: B — 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 Basic Oil & Chemical Tanker operations.

13. What does ISGOTT stand for?

  • A. International Safety Guide for Oil Tankers and Terminals
  • B. Integrated Offshore Safety
  • C. Indian Safety Group
  • D. System for Gas Safety
Answer: A — International Safety Guide for Oil Tankers and Terminals
ISGOTT is the industry standard safety guide published by ICS, OCIMF, and IAPH.

14. What is the function of an Inert Gas Scrubber tower?

  • A. Cool flue gas and remove soot and SO2 particles
  • B. Generate oxygen
  • C. Separate oil and water
  • D. Heat oil
Answer: A — Cool flue gas and remove soot and SO2 particles
Scrubber towers spray seawater to cool flue gas and remove corrosive SO2 and soot.

15. What is Load on Top (LOT) procedure?

  • A. Pumping without sounding
  • B. Overfilling tanks
  • C. Heavy cargo over light cargo
  • D. Decanting clean water under settled slops and loading fresh crude directly on top
Answer: D — Decanting clean water under settled slops and loading fresh crude directly on top
LOT decants separated water via ODMCS, retaining oil slops to merge with new cargo.

16. What risk occurs if static electricity accumulates during initial filling of an un-inerted tank?

  • A. Corrosion
  • B. Electrostatic spark ignition causing tank explosion
  • C. Freezing
  • D. Cavitation
Answer: B — Electrostatic spark ignition causing tank explosion
Static sparks igniting volatile vapors cause catastrophic tank explosions.

17. What is the max initial loading rate velocity for static accumulator oils before inlet pipe is submerged?

  • A. No limit
  • B. 1 meter per second
  • C. 10 m/s
  • D. 50 m/s
Answer: B — 1 meter per second
Linear velocity is restricted to max 1 m/s initially to prevent static charge generation.

18. What safety system automatically shuts down cargo pumps and closes valves in emergencies?

  • A. Emergency Shutdown System (ESD)
  • B. Windlass brake
  • C. Boiler valve
  • D. Bilge valve
Answer: A — Emergency Shutdown System (ESD)
ESD isolates ship and shore cargo lines instantly in emergency conditions.

19. What equipment measures hydrocarbon vapor concentration in zero-oxygen inert atmospheres?

  • A. Catalytic explosimeter
  • B. Hydrometer
  • C. Litmus paper
  • D. Tankscope / Infrared Gas Analyzer
Answer: D — Tankscope / Infrared Gas Analyzer
Tankscopes measure gas concentrations in inert atmospheres where oxygen is zero.

20. What is total oil discharge limit for existing tankers during ballast voyage under MARPOL Annex I?

  • A. 1/1,000
  • B. 100 m3
  • C. Zero everywhere
  • D. Max 1/30,000 of total cargo carried on previous voyage
Answer: D — Max 1/30,000 of total cargo carried on previous voyage
MARPOL caps total ballast discharge oil volume to 1/30,000 of previous cargo.

21. What is the function of stripping pumps during cargo discharge?

  • A. Drain remaining oil liquid from tank bottoms and suction lines
  • B. Cool main deck
  • C. Generate steam
  • D. Pump ballast into fuel tanks
Answer: A — Drain remaining oil liquid from tank bottoms and suction lines
Stripping pumps remove liquid residues when main centrifugal pumps lose suction.

22. What safety document is signed by ship officer and shore representative prior to cargo transfer?

  • A. Waybill
  • B. Crew Agreement
  • C. Custom Clearance
  • D. Ship / Shore Safety Checklist (SSSCL)
Answer: D — Ship / Shore Safety Checklist (SSSCL)
The SSSCL confirms safety precautions, communications, ESD links, and manifold checks.

23. Which international regulation specifies the minimum standard for regulatory compliance and STCW code requirements concerning Basic Oil & Chemical Tanker?

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

24. In the event of an emergency involving regulatory compliance and STCW code requirements during Basic Oil & Chemical Tanker tasks, what immediate action is required?

  • A. Wait until the end of the watch to log the issue
  • B. Evacuate the vessel immediately without informing the bridge
  • C. Attempt to resolve the incident silently without raising the alarm
  • 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 gas present in crude oil vapor is highly toxic with rotten egg smell at low levels?

  • A. Methane
  • B. Nitrogen
  • C. Hydrogen Sulfide (H2S)
  • D. Carbon Dioxide
Answer: C — Hydrogen Sulfide (H2S)
H2S is highly toxic, deadens smell rapidly, and is fatal at high concentrations.

26. What is modern TLV-TWA exposure limit for Hydrogen Sulfide (H2S)?

  • A. 1 ppm to 5 ppm
  • B. 1000 ppm
  • C. 5000 ppm
  • D. 100 ppm
Answer: A — 1 ppm to 5 ppm
Modern ACGIH guidelines specify H2S TLV-TWA of 1 ppm due to high toxicity.

27. What device isolates cargo tank vapor space while maintaining pressure control?

  • A. Sounding cap
  • B. Open stack
  • C. Pressure/Vacuum (P/V) breaker or P/V valves
  • D. Scupper plug
Answer: C — Pressure/Vacuum (P/V) breaker or P/V valves
P/V breakers protect inert gas main lines and tanks from pressure spikes or vacuum.

28. What requirement applies to double hull tankers under MARPOL Annex I?

  • A. Wood lined hold
  • B. Single skin side
  • C. Open bilge
  • D. Double bottom and wing ballast tanks separating cargo tanks from outer hull
Answer: D — Double bottom and wing ballast tanks separating cargo tanks from outer hull
Double hulls protect cargo tanks from rupture during grounding or collision.

29. What action is taken if inert gas oxygen content exceeds 8% during cargo discharge?

  • A. Open tank lids
  • B. Stop cargo discharge immediately and rectify IG plant fault
  • C. Drain scrubber
  • D. Double discharge speed
Answer: B — Stop cargo discharge immediately and rectify IG plant fault
If O2 exceeds 8%, cargo operations must cease until safe inert atmosphere is restored.

30. What is purging on an oil tanker?

  • A. Pumping oil to shore
  • B. Ballasting
  • C. Introducing inert gas into an inerted tank to reduce hydrocarbon concentration before gas freeing
  • D. Washing with seawater
Answer: C — Introducing inert gas into an inerted tank to reduce hydrocarbon concentration before gas freeing
Purging drops hydrocarbon vapor levels low enough that air introduction won't create flammability.

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