This page contains answers to Seagull CES test about COW system (Crude Oil Washing), and serve as a database of questions and answers, using which seafarer can prepare to exams for getting certificate of competence, or just to challenge yourself with knowledge in this theme.
CBT CD 0054 – COW.pdf
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Amount of questions: 28.
Right answers marked with this sign .
According to IMO the Manual has to be approved by the Administration. With regard to general practice who is giving the final approval of the Manual?
The classification society.
The IMO.
The coast guard.
The port state.
Are we allowed to perform COW at sea?
Yes, on ballast passages.
No, we are not allowed to perform COW at sea.
Yes, between discharge ports.
There are no restrictions regarding COW at sea.
From how many or which one of the cargo pumps must it be possible to take “bleed-off” from main(s) for COW supply?
From 50 % of the cargo pumps.
From any one of the cargo pumps.
From at least two of the cargo pumps.
From a particular cargo pump.
How many percent of the cargo tanks to be crude oil washed on rotational basis for sludge control during a 4 months period?
Approximately 25 %.
Approximately 50 %.
Approximately 30 %.
Approximately 10 %.
How to avoid excessive electrostatic generation in the washing process due to the presence of water in the crude oil washing fluid?
By recirculating cargo in the tank before use as a source of washing fluid.
By discharge at least 1 metre from the tank before use as a source of washing fluid.
By heating the cargo in the tank before use as a source of washing fluid.
Increase the inert gas pressure in the tank before use as a source of washing fluid.
How to avoid vapour emission during filling of departure ballast (non SBT vessel)?
By simultaneous ballasting and cargo discharge.
By reduce the IG pressure.
By minimise the amount of departure ballast.
Water, that is put into a tank, which has been crude oil washed but not water washed shall be regarded as:
Clean ballast.
Arrival ballast.
Dirty ballast.
Segregated ballast.
What are the requirements regarding experience for persons, who are intended to have particular responsibilities as defined in the Manual?
They shall have, at least, 6 months experience on oil tankers, where they should have been involved in COW operation.
They shall have, at least, 9 months experience on oil tankers, where they should have been involved in COW operation.
They shall have, at least, 9 months experience on oil tankers, where they should have been involved in COW operation.
With regard to experience, there is no such requirement.
What is IMO’s requirement regarding the oxygen level in the tank before and during it is crude oil washed?
The oxygen level must not exceed 8 % by volume.
The oxygen level must not exceed 10 % by volume.
The oxygen level must not exceed 5 % by volume.
The oxygen level must not exceed 12 % by volume.
What is the difference between SBT-system and CBT-system?
There is no difference.
CBT-system must have separate ballast pumps.
SBT-system can utilise cargo pumps/lines for ballast handling.
CBT-system can utilise cargo pumps/lines for ballast handling.
What is the dissolving effect dependent on?
The type of oil.
The composition of the oil.
The temperature of the oil.
What is the maximum quantity of oil you are permitted to discharge into the sea from an “existing tanker”?
1/20 000 of the total quantity of the cargo.
1/15 000 of the total quantity of the cargo.
1/30 000 of the total quantity of the cargo.
There is no such restriction.
What is the minimum distance from the nearest land when you are pumping departure ballast overboard?
30 nautical miles.
10 nautical miles.
100 nautical miles.
50 nautical miles.
What is the purpose of the small diameter line?
To be utilised when decanting the slop tank.
To discharge ashore the drainings form pumps and lines.
To strip the pump room.
To supply driving media to the eductor.
What is the requirement regarding arrangements for hand dipping the cargo tanks after COW?
Arrangements in the aftermost portion of the tank and in 3 other suitable locations.
Arrangements in each corner of the tank.
Arrangements in the middle of the tank.
Arrangements in the aftermost portion of the tank and in 4 other suitable locations.
What is the requirement regarding capacity of inert gas plant?
Same as the discharging capacity.
At least 125 % of the maximum discharge capacity.
At least 115 % of the maximum discharge capacity.
There is no such requirement.
What is the requirement regarding hydrant valves on the COW line?
No requirement.
They must be blanked off.
They must be fitted with a special cap.
They must be disconnected.
What is the requirement regarding stripping system capacity when washing bottom of the cargo tanks?
There is no requirement to stripping capacity.
The stripping capacity must be 25 % more, than the total throughput of washing fluid.
The stripping capacity must be 50 % more, than the total throughput of washing fluid.
The stripping capacity must be 10 % more, than the total throughput of washing fluid.
What is the requirement to the number of drive units on vessels, equipped with tank washing machines, where the drive units are detachable?
No particular requirement.
That no drive unit has to be shifted more than 3 times.
That no drive unit has to be shifted more than twice.
That no drive unit has to be shifted more than once.
What kind of action must be taken in the event of total failure of the inert gas system during discharge/COW?
Stop the discharge/COW.
Call the Chief Engineer.
Stop the COW and reduce the discharge rate.
What kind of action to be taken if an alternation affecting the crude oil washing system is made?
Advise IMO.
Advise port state.
Revise the Manual.
Advise the coast guard.
What requirements must the person in charge of COW operation meet with regard to the COW Manual?
Be familiar with the Manual.
Been instructed in the content of the Manual.
Be fully knowledgeable of the content of the Manual.
Have detailed knowledge of the Manual.
Where in the tank shall the oxygen level be determined before crude oil washing?
1 metre from the deck and in the bottom of the tank.
In the middle of the tank.
1 metre from the deck and in the middle region of the ullage space.
2 metre from the deck and in the middle region of the ullage space.
Where shall the verification of submerged washing machines be recorded?
In the deck logbook.
In the engine logbook.
In the PMS (planned maintenance system).
In the Supplement 2 to the Oil Record Book.
Where should you record the crude oil washing after completion?
Oil Record Book.
Cow Manual.
Pumping Log.
Inert plant manual.
Who is signing the Ship/Shore Safety Checklist?
Chief officer.
Ship and Shore Representative.
The surveyor.
The Captain.
Why is COW more efficient than water washing?
Because the cargo is circulated through fixed washing machines.
Because tank corrosion is reduced.
Because of the dissolving property in crude.
Because of the “splash-back-effect”.
Why was COW made compulsory?
To reduce amount of sludge in cargo tanks.
To reduce pollution.
To improve cargo outturn.
To prevent corrosion in cargo tanks.
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