CHEMCO exit exam questions and answers — Set 8 — Advanced Training for Chemical Tanker Cargo Operations
Set 8 of the Advanced Training for Chemical Tanker Cargo Operations (CHEMCO) exit exam bank — 30 of 663 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.
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Set 8 — 30 CHEMCO exit exam questions with answers
1. Why is it the potential for volumetric losses is greater where COW is performed?
- A. During COW, the cargo is being formed into a low pressure spray and completely atomised
- B. During COW, the cargo is being formed into a high pressure spray and completely atomised
- C. During COW, the cargo is being formed into a high pressure spray and partially atomised
- D. During COW, the cargo is being formed into a low pressure spray and partially atomised
Answer: C — During COW, the cargo is being formed into a high pressure spray and partially atomised
During COW the crude oil is delivered through washing machines as a high pressure jet, which becomes partially atomised. This releases light hydrocarbon fractions as vapour, increasing the potential for volumetric loss.
2. When the sea conditions are not exactly calm, how will you make sure that the ullage measurement reading is closer to accurate?
- A. For each tank, take 5 ullage measurements and average, then apply trim correction
- B. For each tank, take 3 ullage measurements and average, then apply trim correction
- C. For each tank, take 5 ullage measurements, leave the maximum and minimum values, then average the remaining three values and apply trim correction
- D. For each tank, take 5 ullage measurements, leave the maximum and minimum values, then average the remaining three values.
Answer: C — For each tank, take 5 ullage measurements, leave the maximum and minimum values, then average the remaining three values and apply trim correction
In a seaway the liquid surface moves, so several readings are taken and the extreme high and low values are discarded to remove the worst wave effects. The remaining three readings are averaged and the trim correction is then applied to obtain a representative corrected ullage for cargo calculation.
3. Select the appropriate sentence from below describing the ‘Oil Shortage claim’
- A. The discrepancy between what has been received on board and what has been discharged from the ship
- B. The discrepancy between what has been received on board as per B/L and what has been discharged from the ship
- C. The discrepancy between the quantity of cargo as stated in the B/L and the out turn quantity as calculated in the discharge port.
- D. The discrepancy between the quantity of cargo as stated in the B/L and the out turn quantity as calculated in the discharge port after due consideration for the allowable transportation loss
Answer: D — The discrepancy between the quantity of cargo as stated in the B/L and the out turn quantity as calculated in the discharge port after due consideration for the allowable transportation loss
A shortage claim arises from the difference between the Bill of Lading quantity and the outturn quantity measured at the discharge port, but only after allowing for the accepted transportation loss. Small losses from evaporation, clingage and measurement tolerance are normal and are not treated as a claimable shortage.
4. How to find out ‘True in-Transit losses’ during the voyage?
- A. The ship’s gross volume at normal temperature on loading is compared with the ship’s gross volume at normal temperature prior to discharge
- B. The ship’s gross volume at atmospheric temperature on loading is compared with the ship’s gross volume at atmospheric temperature prior to discharge
- C. The ship’s gross volume at standard temperature on loading is compared with the ship’s gross volume at standard temperature prior to discharge
- D. The ship’s gross volume at atmospheric temperature & pressure on loading is compared with the ship’s gross volume at atmospheric temperature & pressure prior to discharge
Answer: C — The ship’s gross volume at standard temperature on loading is compared with the ship’s gross volume at standard temperature prior to discharge
True in-transit loss is found by comparing the ship's gross volume corrected to standard temperature (15°C or 60°F) on completion of loading with the gross standard volume just before discharge. Correcting both figures to the same standard temperature removes thermal expansion effects, leaving the real change in quantity.
5. What are all the records, if maintained onboard will assist in case of claims /disputes?
- A. Voyage abstract (deck), notice of readiness (NOR), port log, Cargo pumping/loading/transfer records and Oil record book including bunker operations
- B. Voyage abstract (deck and engine), notice of readiness (NOR), port log, Cargo pumping/ transfer records and Oil record book including bunker operations
- C. Voyage abstract (deck and engine), notice of readiness (NOR), port log, Cargo pumping/loading/transfer records and Oil record book.
- D. Voyage abstract (deck and engine), notice of readiness (NOR), port log, Cargo pumping/loading/transfer records and Oil record book including bunker operations
Answer: D — Voyage abstract (deck and engine), notice of readiness (NOR), port log, Cargo pumping/loading/transfer records and Oil record book including bunker operations
In a cargo dispute the most complete set of evidence is needed: deck and engine voyage abstracts, the notice of readiness, port log, cargo loading, pumping and transfer records, and the Oil Record Book including bunker operations. Together these show timings, quantities and any internal transfers that could explain discrepancies.
6. How to find out ‘Theoretical in-Transit losses’ during the voyage?
- A. The ship’s net volume on board at standard temperature on completion of loading is compared with the net volume on board at standard temperature prior to the commencement of discharge emptying and filling losses.
- B. The ship’s net volume on board at normal temperature & pressure on completion of loading is compared with the net volume on board at normal temperature & pressure prior to the commencement of discharge emptying and filling losses.
- C. The ship’s gross volume on board at standard temperature on completion of loading is compared with the net volume on board prior to the commencement of discharge emptying and filling losses.
- D. The ship’s net volume on board at standard temperature on completion of loading is compared with the gross volume on board at standard temperature prior to the commencement of discharge emptying and filling losses.
Answer: A — The ship’s net volume on board at standard temperature on completion of loading is compared with the net volume on board at standard temperature prior to the commencement of discharge emptying and filling losses.
Theoretical in-transit loss compares the ship's net volume corrected to standard temperature on completion of loading with the net standard volume on board just before discharge commences. Using net figures at the same standard temperature excludes free water and thermal expansion, so only the apparent quantity change during the voyage remains.
7. What are the international classification that describes petroleum liquid cargoes ?
- A. flammable and combustible
- B. volatile and non-volatile
- C. Organic and Inorganic
- D. Acidic and non-acidic
Answer: B — volatile and non-volatile
ISGOTT classifies petroleum liquid cargoes as volatile or non-volatile, based on flash point. Non-volatile petroleum has a flash point of 60°C or above, while volatile petroleum has a flash point below 60°C and can produce flammable gas at normal ambient temperatures.
8. Petroleum liquids derived from the naturally occurring crude oil that may include the following
- A. Gasoline, Lubricant, Asphalt
- B. Phosphoric acid, Sulfuric acid, Hydrochloric acid
- C. Caustic soda, molten sulfur, Boric acid
- D. Tallow, grease, molasses
Answer: A — Gasoline, Lubricant, Asphalt
Gasoline, lubricating oils and asphalt (bitumen) are all products refined from naturally occurring crude oil. The acids, caustic soda, molten sulphur, tallow and molasses in the other choices are inorganic chemicals or animal and vegetable products, not petroleum derivatives.
9. The EmS guide is given in
- A. Volume 1 of IMDG code
- B. Volume 2 of IMDG code
- C. IMDG code supplement
- D. SOLAS
Answer: C — IMDG code supplement
The Emergency Response Procedures for Ships Carrying Dangerous Goods (EmS Guide) is published in the IMDG Code Supplement, together with the Medical First Aid Guide (MFAG). Volumes 1 and 2 contain the main provisions and the Dangerous Goods List, which gives the EmS fire and spillage schedule codes.
10. MARPOL Annex I came into force in
- A. 1987
- B. 1983
- C. 1992
- D. 2003
Answer: B — 1983
MARPOL 73/78, including the mandatory Annex I on prevention of pollution by oil, entered into force on 2 October 1983. Annex II for noxious liquid substances followed later, in April 1987.
11. How to reduce Hydrogen Sulphide Hazard in Residual Fuel Oils?
- A. Ventilation to lower the concentration of vapour in the ullage space and in specific areas where vapours may accumulate should be carried out as soon as practicable.
- B. Transfer the oil to some other tank using fuel transfer pump,
- C. Keep heating the oil to maintain a higher temperature
- D. Circulate the oil in the same tank using the fuel transfer pump
Answer: A — Ventilation to lower the concentration of vapour in the ullage space and in specific areas where vapours may accumulate should be carried out as soon as practicable.
Hydrogen sulphide released from residual fuel oil accumulates in the tank ullage space and nearby areas. ISGOTT advises reducing the hazard by ventilating these spaces as soon as practicable to lower the vapour concentration, while transferring, circulating or heating the oil would release more H2S.
12. What is pressure surge ?
- A. When the pressure of oil increases suddenly at the manifold
- B. When the pressure of oil decreases suddenly at the manifold
- C. When the discharge pressure at the pump drops to zero
- D. A sudden increase in the pressure of the liquid in a pipeline brought about by an abrupt change in flow rate
Answer: D — A sudden increase in the pressure of the liquid in a pipeline brought about by an abrupt change in flow rate
ISGOTT defines a pressure surge as a sudden increase in liquid pressure in a pipeline caused by an abrupt change in flow rate, typically from rapid valve closure. The surge travels along the line and can rupture hoses, loading arms or pipework, so valve closure times must be controlled.
13. Burning of candle is an example of ______________.
- A. rapid combustion
- B. spontaneous combustion
- C. slow oxidation
- D. explosion
Answer: A — rapid combustion
A candle flame is a self-sustaining rapid oxidation producing heat and light (rapid combustion); slow oxidation is rusting, spontaneous combustion needs no ignition source.
14. What is flammable range ?
- A. The range in which nothing will burn
- B. The range in which the oxygen content is too low to cause explosion
- C. The range in which the oxygen content is too high to cause explosion
- D. The range of hydrocarbon gas concentrations in air between the lower and upper flammable limits. Mixtures within this range are capable of being ignited and of burning.
Answer: D — The range of hydrocarbon gas concentrations in air between the lower and upper flammable limits. Mixtures within this range are capable of being ignited and of burning.
ISGOTT defines the flammable range as the range of hydrocarbon gas concentrations in air between the lower and upper flammable limits. Mixtures inside this range can be ignited and will burn, while mixtures below the LFL are too lean and those above the UFL are too rich.
15. What is the eight-hour safe exposure limit for Carbon Monoxide?
- A. 15ppm
- B. 25ppm
- C. 125ppm
- D. 250ppm
Answer: B — 25ppm
The commonly applied 8-hour time-weighted average exposure limit (TLV-TWA) for carbon monoxide is 25 ppm. CO is colourless and odourless and combines with haemoglobin far more readily than oxygen, so even low continuous concentrations are dangerous.
16. What is Oxygen deficiency?
- A. Oxygen less than 21%
- B. Oxygen less than 16%
- C. Oxygen less than 8%
- D. Oxygen less than 5%
Answer: A — Oxygen less than 21%
ISGOTT describes an oxygen-deficient atmosphere as one containing less than 21% oxygen by volume, the normal content of air. Any reading below 21% means something has displaced or consumed oxygen, and the space must not be entered without further ventilation and testing.
17. It is possible to find the appropriate EmS SPILLAGE SCHEDULE from the
- A. Proper shipping name
- B. UN Number
- C. Packing group
- D. Packing instructions
Answer: B — UN Number
Each entry in the IMDG Dangerous Goods List is identified by its UN number, and column 15 gives the EmS codes, such as F-E and S-D, for that UN number. The spillage schedule is therefore found by looking up the UN number.
18. Pyrophoric oxidation occurs when loading:
- A. Light crude oils
- B. Sour crude oils
- C. Refined products
- D. Chemical cargoes
Answer: B — Sour crude oils
Sour crude oils contain hydrogen sulphide, which reacts with rust in tanks lacking oxygen to form pyrophoric iron sulphide. When air later reaches these deposits they oxidise rapidly and can glow red hot, igniting flammable gas, which is why inert gas is kept in tanks carrying sour crude.
19. Systemic poisons are those that cause an adverse health effect on------------
- A. the whole body
- B. several organs of the human body
- C. the skin only
- D. a specific organ
Answer: D — a specific organ
Systemic toxins are absorbed into the bloodstream and produce harmful effects at a site away from the point of contact, typically a target organ such as the liver, kidneys or nervous system. The bank defines this as damage to a specific organ, unlike local irritants that act only on the skin.
20. The products of combustion are
- A. carbon dioxide and water
- B. oxygen and water
- C. only carbon dioxide
- D. only oxygen
Answer: A — carbon dioxide and water
Complete combustion of hydrocarbon fuels with sufficient oxygen produces carbon dioxide and water vapour, while releasing heat. Oxygen is consumed in the reaction, so it cannot be a product, and water is always formed from the hydrogen in the fuel.
21. In the burning process hydrocarbon gases react with oxygen in the air:
- A. To produce carbon and water
- B. To produce hydrogen and water
- C. To produce carbon dioxide and water
- D. To produce carbon monoxide and water
Answer: C — To produce carbon dioxide and water
When hydrocarbon gases burn, carbon combines with oxygen to form carbon dioxide and hydrogen combines with oxygen to form water. Carbon monoxide or soot forms only when combustion is incomplete because there is not enough oxygen.
22. Buildup of electrostatic charge when loading static accumulator oils is avoided by:
- A. Increasing the flow rate
- B. Not using natural fibre ropes in ullaging equipment
- C. Taking tank soundings within a metal sounding pipe
- D. Fitting, fixed equipment away from the tank wall
Answer: C — Taking tank soundings within a metal sounding pipe
ISGOTT allows dipping, ullaging and sampling of static accumulator cargoes in a non-inerted tank when done within a sounding pipe, because the earthed metal pipe prevents charge from building up on the liquid surface around the equipment. Increasing flow rate would generate more static charge.
23. What is a resuscitator ?
- A. Equipment to revive an unconscious person
- B. To supply air to a person in a tank
- C. Equipment to restore the breathing of a person overcome by gas or lack of oxygen
- D. It is a rescue equipment for use in emergency
Answer: C — Equipment to restore the breathing of a person overcome by gas or lack of oxygen
A resuscitator is a device that supplies oxygen or air under controlled pressure to restore breathing in a casualty overcome by gas or lack of oxygen. Tankers carry one under SOLAS for enclosed space rescue, and it is used by trained persons after the casualty has been removed.
24. What is the TLV-TWA for hydrogen sulphide over a period of 8 hours ?
- A. 5 ppm
- B. 10 ppm
- C. 15 ppm
- D. 20 ppm
Answer: A — 5 ppm
ISGOTT gives an 8-hour time-weighted average TLV for hydrogen sulphide of 5 ppm, with a short-term limit of 10 ppm. Above about 100 ppm H2S paralyses the sense of smell, so odour can never be relied upon for detection.
25. The International Medical Guide for Ships gives guidelines on how to diagnose, treat and prevent health problems in seafarers, mainly focusing on the first _____________ hours after injury.
- A. 6
- B. 48
- C. 12
- D. 24
Answer: B — 48
The International Medical Guide for Ships, published by WHO with IMO and ILO, is written to help non-medical crew diagnose, treat and prevent health problems on board. The bank states that it concentrates on care during the first 48 hours after injury, before shore medical help can be obtained.
26. When required to work in an area where explosive gases may accumulate, you should use tools which are
- A. approved by the Coast Guard
- B. high carbon steel
- C. fixed with a ferrous cover
- D. non-sparking
Answer: D — non-sparking
Where explosive gas can accumulate, only non-sparking tools should be used, typically made of beryllium copper or other non-ferrous alloys. Steel tools striking steel can produce incendive sparks able to ignite a flammable gas mixture.
27. Multi-gas instruments are widely used and are usually capable of housing four different sensors. A typical configuration would comprise sensors for measuring: identify one that will be of major importance for enclosed space entry,
- A. Hydrocarbon vapor as a % LFL (explosimeter function using a pellistor sensor).
- B. Hydrocarbon vapor in inert gas as a % Volume (tankscope function using an infra-red sensor).
- C. Oxygen (using an electrochemical sensor).
- D. Hydrogen Sulfide (using an electrochemical sensor).
Answer: C — Oxygen (using an electrochemical sensor).
For enclosed space entry the first priority is confirming normal oxygen content, measured with the electrochemical oxygen sensor of a multi-gas meter. ISGOTT requires a steady 21% oxygen reading before entry, along with acceptable hydrocarbon and toxic gas levels.
28. Tanker pump room ventilation must be switched on at least how many minutes before entry ?
- A. 10 minutes
- B. 15 minutes
- C. 30 minutes
- D. One hour
Answer: C — 30 minutes
Cargo pump room ventilation must run long enough to remove accumulated vapours and give adequate air changes before anyone enters. The bank takes 30 minutes as the minimum period, after which the atmosphere is tested and the entry permit procedures under SOLAS II-2 and ISGOTT are followed.
29. Which of the following hazards is the main concern when entering a ballast tank?
- A. toxic gases
- B. flammable gases
- C. infection
- D. lack of oxygen
Answer: D — lack of oxygen
Ballast tanks are kept closed and their steel surfaces corrode, a process that consumes oxygen from the trapped air. The main entry hazard is therefore oxygen deficiency, so ventilation and oxygen testing are essential before entry.
30. A crew member is unconscious and the face is flushed. You should __________.
- A. lay the crew member down with the head and shoulders slightly raised
- B. administer a liquid stimulant
- C. lay the crew member down with the head lower than the feet
- D. attempt to stand the crew member upright to restore consciousness
Answer: A — lay the crew member down with the head and shoulders slightly raised
A flushed face suggests raised blood pressure or blood flow to the head, such as from stroke or heat stroke. The casualty should be laid down with head and shoulders slightly raised to reduce pressure in the head, never given liquids while unconscious and never stood upright.
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