CHEMCO exit exam questions and answers — Set 7
Set 7 of the Advanced Training for Chemical Tanker Cargo Operations (CHEMCO) exit exam bank — 30 of 377 questions, with the correct option marked. This bank is answer-only: the source published no usable explanations for it, so there are none here either. 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 7 — 30 CHEMCO exit exam questions with answers
1. Flue gas is drawn from the boiler uptake and delivered to the inert gas scrubber by a:
- A. Exhaust gas pressure from the stack
- B. High capacity fan
- C. Inert gas compressor
- D. Natural aspiration
2. What is the major function of the deck water seal in an inert gas system?
- A. Relieves excessive pressures from the system.
- B. Isolates hazardous areas from nonhazardous areas.
- C. Prevents the flow of inert gas into closed or isolated tanks.
- D. Removes any leftover water or soot after the gas has been scrubbed.
3. Inert gas systems must be capable of delivering inert gas with an oxygen content by volume in the inert gas main of not more than
- A. 2%
- B. 5%
- C. 8%
- D. 11%
4. On a hydrocarbon flammability chart the line which extends from 0% to 21.8% oxygen, lying tangent to the flammability range, is called the
- A. minimum oxygen content line upper threshold limit
- B. critical displacement line
- C. critical dilution line
- D. upper threshold limit
5. The component in an inert gas system used for cleaning the gas of solid and sulfur combustion products, while simultaneously cooling the inert gas, is called the
- A. filter
- B. cooler
- C. scrubber
- D. purifier
6. Inert gas systems must be capable of maintaining inert gas with an oxygen content by volume in the cargo tanks of not more than
- A. 2%
- B. 5%
- C. 8%
- D. 11%
7. You are discharging cargo and the inert gas system is in operation to inert the tanks. The pressure in a tank being discharged starts to drop below the allowable limit. What action should you take?
- A. Cut in another IG fan to increase gas flow.
- B. Open the pressure control valve until the pressure increases.
- C. Open the tank isolation valve to the fully open position.
- D. Reduce the pumping rate.
8. The fresh air intake of the inert gas system
- A. prevents the flue gas from falling below an oxygen content of 3%
- B. allows the inert gas piping to be used for gas freeing the tanks
- C. opens when there is excessive vacuum on the deck water seal
- D. enables outside air to mix with and to cool the hot flue gasses
9. What is the maximum oxygen content below which flaming combustion will no longer occur?
- A. 5%
- B. 8%
- C. 10%
- D. 12%
10. In which of the following conditions, the IG blower fans should shut down automatically?
- A. Oxygen content above 8%
- B. Low water level in deck seal
- C. Low water level in the scrubber tower
- D. High scrubber water level
11. What type of liquid is used in the liquid P/V breaker?
- A. Hydraulic oil
- B. Water-antifreeze mixture
- C. Distilled water
- D. Oil from the cargo
12. What is the maximum percent of oxygen, by volume, allowed to be maintained in the cargo tanks prior to the commencement of crude oil tank washing?
- A. 5%
- B. 8%
- C. 10%
- D. 12%
13. Checks to be done, amongst others, before and during COW are listed; identify the most important safety check
- A. When carrying out crude oil washing during cargo discharge, the Master should inform the terminal competent authority 24 hours before commencement (or other ship when ship-to-ship transfer is involved)
- B. The Oxygen analyzing equipment to be tested and working satisfactorily
- C. Inert gas in tank to be checked – (Oxygen to be less than 8%), IG pressure to be satisfactory (positive pressure)
- D. All hydrant valves on the tank washing line to be shut
14. Concurrent COW with cargo discharge: identify the precaution for the Concurrent COW method for use
- A. COW concurrent method utilizes the crude oil stream being discharged, together with its associated back pressure, to supply the COW pipeline with crude oil.
- B. COW concurrent method can be achieved either by a "bleed-off' system from the main crude oil discharge pipelines for supply to the COW pipeline or by separate supply using a designated cargo pump.
- C. COW concurrent method: The normal minimum back pressure required for the operation of the COW guns is 8 kg/cm2.
- D. COW concurrent method: If supply is achieved by the bleed-off from the bulk discharge, then sufficient back pressure has to be maintained at all times.
15. When evacuating a seaman by helicopter lift, the vessel should be__________.
- A. stopped with the wind dead ahead
- B. stopped with the wind on the beam
- C. underway with the wind 30° on the bow
- D. underway on a course to provide no apparent wind
16. A rescue helicopter's hoist area should have a radius of at least __________.
- A. 6 feet of clear deck
- B. 10 feet of clear deck
- C. 25 feet of clear deck
- D. 50 feet of clear deck
17. Usually the most gentle way of riding out a severe storm on a larger vessel is__________.
- A. head on at slow speeds
- B. hove to
- C. running before the seas
- D. to rig a sea anchor
18. Your vessel is off a lee shore in heavy weather and laboring. Which action should you take?
- A. Put the sea and wind about two points on either bow and reduce speed.
- B. Heave to in the trough of the sea.
- C. Put the sea and wind on either quarter and proceed at increased speed.
- D. Put the bow directly into the sea and proceed at full speed.
19. You are steaming in a heavy gale and find it necessary to heave to. Under most circumstances, this is best done by __________.
- A. stopping the engines and drifting beam to the seas
- B. going slow astern and taking the seas on the quarter
- C. taking the sea fine on the bow and reducing the speed to the minimum to hold that position
- D. maintaining speed and taking the sea broad on the bow
20. Snow has obliterated surface features and the sky is covered with uniform, altostratus clouds. There are no shadows and the horizon has disappeared. What is this condition called?
- A. Ice blink
- B. Whiteout
- C. Water sky
- D. Aurora reflection
21. A vessel is wind rode when it is __________.
- A. at anchor and heading into the wind
- B. backing into the wind
- C. carrying lee rudder
- D. necessary to apply a leeway correction to the course
22. When evacuating a seaman by helicopter lift, which course should the ship take?
- A. Downwind so that the apparent wind is close to nil.
- B. A course that will keep a free flow of air, clear of smoke, over the hoist area.
- C. A course that will have the hoist area in the lee of the superstructure.
- D. With the wind dead ahead because the helicopter is more maneuverable when going into the wind.
23. When the gyro-pilot is used for steering, what control is adjusted to compensate for varying sea conditions?
- A. Rudder control
- B. Sea control
- C. Lost motion adjustment
- D. Weather adjustment
24. What types of mooring lines are used for larger tankers?
- A. Ropes with high elastic elongation properties
- B. Ropes with low plastic elongation properties
- C. Ropes with high modulus of rigidity
- D. Strain hardened ropes
25. Normally Brakes must be ___________tightened to achieve the required holding capacity of the line's Minimum Breaking Load.
- A. 30%
- B. 50%
- C. 60%
- D. 75%
26. ‘It is preferred to have all mooring lines of the same material and construction’ This is strictly followed due to
- A. The load on all the mooring lines should be same
- B. To avoid undue stress on mooring lines
- C. To increase the life of the mooring lines
- D. To avoid compressive over loading of any of the mooring ropes
27. How to prevent failure of the mooring and other components in the mooring system during large swell conditions?
- A. By attaching fibre tails in the mooring ropes
- B. By attaching fibre tails on the ends in the mooring ropes
- C. By attaching fibre tails on the sides of the mooring ropes
- D. By attaching fibre tails perpendicular to the mooring ropes
28. Mooring winch brakes should be tested at regular intervals, not exceeding _____. Choose the correct period from below?
- A. 18 months
- B. 12 months
- C. 24 months
- D. 30months
29. What is the possible alternate for winch-stowed steel wire ropes for the mooring of large tankers at terminals?
- A. Low Modulus synthetic fibre ropes
- B. High Modulus synthetic wire ropes
- C. High Modulus synthetic fibre ropes
- D. Low Modulus nylon ropes
30. Why mooring wires used by large tankers are normally stored on self- stowing mooring winches?
- A. Self - stowing winches are convenient
- B. Weight and size make manual handling difficult
- C. Self – stowing winches have brakes
- D. Self-stowing winches are reliable
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