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CHEMCO exit exam questions and answers — Set 21 — Advanced Training for Chemical Tanker Cargo Operations

Set 21 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 21 — 30 CHEMCO exit exam questions with answers

1. What is the main purpose of taking a 'first foot' sample at the start of loading?

  • A. To check the cargo quality in the tank and line before the bulk of the parcel is loaded, so contamination is detected early
  • B. To measure the ullage after one foot of loading
  • C. To calibrate the shore flow meter
  • D. To test the high-level alarm
Answer: A — To check the cargo quality in the tank and line before the bulk of the parcel is loaded, so contamination is detected early
Loading is stopped after a small quantity, about one foot of cargo, has entered the tank, and samples are analysed. If the cargo is contaminated by the tank or lines, the problem affects only a small quantity and loading can be stopped before the whole parcel is spoiled.

2. Why is loading started at a slow rate before increasing to the agreed maximum rate?

  • A. To confirm cargo is entering the correct tank and there are no leaks before increasing flow
  • B. To allow the cargo to cool in the lines
  • C. To let the shore pumps warm up
  • D. To reduce the vapour pressure of the cargo
Answer: A — To confirm cargo is entering the correct tank and there are no leaks before increasing flow
At the initial slow rate the officer checks that the correct tank valves are open, the cargo is reaching the nominated tank, no other tank level is rising, and the manifold and lines are tight. Only then is the rate increased as agreed with the terminal.

3. For a static accumulator cargo loaded into a tank that is not inerted, what initial flow velocity limit is recommended by ISGOTT until the tank inlet is well covered?

  • A. 1 m/s in the branch line to the tank
  • B. 7 m/s
  • C. 12 m/s
  • D. No limit if the cargo is chemical
Answer: A — 1 m/s in the branch line to the tank
Splashing and high flow rates generate static charge in non-conducting cargoes. ISGOTT recommends limiting the linear velocity in the tank inlet branch to 1 m/s until the inlet is submerged and splashing has stopped, after which the rate can be increased within limits.

4. When topping off a cargo tank, which practice is correct?

  • A. Give the terminal advance notice, reduce the loading rate and never close the last valve against the full flow
  • B. Close all tank valves quickly at the same time
  • C. Increase the rate so the tank fills before the next tank is opened
  • D. Rely only on the overfill alarm to stop loading
Answer: A — Give the terminal advance notice, reduce the loading rate and never close the last valve against the full flow
Topping off is a critical stage: the terminal must be told in good time to reduce rate, tanks are topped one at a time under close watch, and valves are not closed against the flow, which could cause pressure surge or force cargo into other tanks.

5. At the end of loading, the shore line is blown clear into the ship with nitrogen or compressed air. Which precaution is most important?

  • A. Keep a receiving tank with sufficient ullage open and control the gas pressure to avoid overflow, splashing or overpressurising the tank
  • B. Close all tank valves so the gas stays in the line
  • C. Open the ullage ports of all tanks
  • D. Blow the line at maximum available pressure to finish quickly
Answer: A — Keep a receiving tank with sufficient ullage open and control the gas pressure to avoid overflow, splashing or overpressurising the tank
Line blowing pushes a slug of liquid followed by a large volume of gas into the tank. The receiving tank must have ullage and venting capacity, the gas pressure and volume must be agreed and controlled, and the operation watched to prevent overflow, cargo mist and tank overpressure.

6. During discharge of a nitrogen-padded cargo, what must be done to maintain the tank atmosphere?

  • A. Supply nitrogen into the tank to replace the volume of liquid discharged and prevent air entry or vacuum
  • B. Open the ullage port to let in fresh air
  • C. Stop the P/V valve from operating
  • D. Discharge only half the tank and leave the rest on board
Answer: A — Supply nitrogen into the tank to replace the volume of liquid discharged and prevent air entry or vacuum
As liquid leaves the tank a matching volume of gas must enter. For padded cargoes this is nitrogen from the ship's or shore supply, which keeps oxygen and moisture out and prevents the vacuum valve from drawing in air or the tank structure being exposed to vacuum.

7. Why may a high-viscosity cargo need to be heated before and during discharge?

  • A. To reduce viscosity for pumping and stripping and, under MARPOL Annex II, to keep it above the temperature at which it becomes high-viscosity or solidifying
  • B. To increase its vapour pressure for vapour return
  • C. To raise its flash point
  • D. To kill bacteria in the cargo
Answer: A — To reduce viscosity for pumping and stripping and, under MARPOL Annex II, to keep it above the temperature at which it becomes high-viscosity or solidifying
Heating lowers viscosity, improving pump performance and stripping. Under Annex II, viscosity and solidification are judged at the unloading temperature, so keeping the cargo at the required temperature can avoid it being classed as high-viscosity or solidifying and needing a mandatory prewash.

8. What should be checked daily during the passage for cargoes in transit on a chemical tanker?

  • A. Tank pressures, cargo temperatures, padding/inert pressure, cofferdam and void space condition, and inhibitor expiry for inhibited cargoes
  • B. Only the ullages of empty tanks
  • C. Only the main engine fuel consumption
  • D. The bill of lading quantities
Answer: A — Tank pressures, cargo temperatures, padding/inert pressure, cofferdam and void space condition, and inhibitor expiry for inhibited cargoes
Care of cargo in transit includes monitoring tank pressure and temperature, maintaining nitrogen padding or inerting, checking for leakage into cofferdams or adjacent spaces, and confirming inhibited cargoes remain within the inhibitor's effective life, with readings recorded.

9. Several grades are loaded at the same time through different manifolds. Which measure is most important to prevent cross-contamination?

  • A. Positive segregation of each line by blanks or double valve separation and verification of every valve before starting
  • B. Using one common line for all grades and flushing it between parcels
  • C. Loading all grades at the same rate
  • D. Keeping the crossover valves open to equalise pressure
Answer: A — Positive segregation of each line by blanks or double valve separation and verification of every valve before starting
Each parcel must follow its own line from manifold to tank. Line segregation, usually two valves or a blank between grades, is checked against the line-up drawing, and valve settings are double-checked before flow starts so that no grade can enter another grade's system.

10. Under ISGOTT, who must complete the Ship/Shore Safety Checklist?

  • A. The responsible officer of the ship and the terminal representative, jointly
  • B. The master only
  • C. The terminal representative only
  • D. The charterer's surveyor
Answer: A — The responsible officer of the ship and the terminal representative, jointly
The Ship/Shore Safety Checklist is a joint document. The responsible officer and the terminal representative check each item, agree on operational limits and communications, and sign it before transfer starts, with repetitive checks made at agreed intervals during the operation.

11. What is the purpose of the pre-transfer conference between ship and terminal before chemical cargo operations?

  • A. To agree the cargo grades, sequence, rates, pressures, emergency stop procedures and communications
  • B. To agree the freight rate
  • C. To decide which crew members may go ashore
  • D. To settle cargo quantity disputes from the previous port
Answer: A — To agree the cargo grades, sequence, rates, pressures, emergency stop procedures and communications
Before transfer the ship and terminal exchange information on cargo properties and hazards, nominated quantities, sequence and maximum rates, line and manifold pressure limits, venting or vapour return, emergency shutdown and signals, so both sides operate to one agreed plan.

12. Which information must the ship have about every cargo before it is loaded, under IBC Code 16.2?

  • A. A full description of physical and chemical properties including reactivity, actions in case of spills or leaks, countermeasures against personal contact, and fire-fighting procedures
  • B. Only the commercial name and quantity
  • C. The price of the cargo and buyer's name
  • D. The cargo's country of origin
Answer: A — A full description of physical and chemical properties including reactivity, actions in case of spills or leaks, countermeasures against personal contact, and fire-fighting procedures
IBC Code 16.2 requires that cargo information be on board and available to all concerned, including properties, reactivity, spill actions, personal contact countermeasures, fire-fighting media and procedures, and transfer, tank cleaning, gas-freeing and ballasting procedures. Cargo not accompanied by this information must not be loaded.

13. What is the correct action if, during loading, the level is found rising in a tank that is not supposed to receive cargo?

  • A. Stop loading immediately, find the cause such as an open valve or leaking valve, and correct it before restarting
  • B. Continue loading and correct it after completion
  • C. Open the tank's ullage port and monitor
  • D. Increase the rate to finish quickly
Answer: A — Stop loading immediately, find the cause such as an open valve or leaking valve, and correct it before restarting
An unexpected level rise means cargo is going to the wrong tank, possibly mixing grades or overflowing an unprepared tank. Cargo transfer must be stopped, the terminal informed, the line-up checked and the problem corrected before transfer resumes.

14. Before the first cargo enters a tank, which inspection is normally carried out by the cargo surveyor and ship's officer?

  • A. Visual inspection of the tank for cleanliness and dryness, and wall-wash results where required, followed by issue of a tank acceptance certificate
  • B. Inspection of the engine room bilges
  • C. Inspection of the crew accommodation
  • D. Testing of the lifeboat engine
Answer: A — Visual inspection of the tank for cleanliness and dryness, and wall-wash results where required, followed by issue of a tank acceptance certificate
Sensitive chemical cargoes require tanks, lines and pumps to be clean, dry and odour-free. The surveyor inspects the tanks, may take wall-wash samples for analysis and, if satisfied, issues an acceptance certificate before loading begins.

15. When ballasting a chemical tanker during cargo discharge, the main purpose of following the planned ballast sequence is to:

  • A. Keep stress, stability, trim and draught within limits throughout the operation
  • B. Wash the cargo tanks with ballast water
  • C. Avoid using the ballast pump
  • D. Increase the cargo pump discharge rate
Answer: A — Keep stress, stability, trim and draught within limits throughout the operation
As cargo leaves the ship, ballast is taken in a planned sequence so that bending moments, shear forces, GM, trim, air draft and propeller immersion remain within limits at every stage, and the ship is ready for sea at completion.

16. Under the STCW and MLC rest-hour rules, what is the minimum rest that a seafarer involved in cargo operations must have?

  • A. 10 hours in any 24-hour period and 77 hours in any 7-day period
  • B. 6 hours in any 24-hour period and 42 hours in any 7-day period
  • C. 8 hours in any 24-hour period and 56 hours in any 7-day period
  • D. 12 hours in any 24-hour period and 84 hours in any 7-day period
Answer: A — 10 hours in any 24-hour period and 77 hours in any 7-day period
STCW regulation VIII/1 and MLC 2006 standard A2.3 require at least 10 hours of rest in any 24-hour period, in no more than two periods one of which is at least 6 hours, and 77 hours in any 7-day period, which must be planned into cargo watch rotas.

17. Why should the cargo operation plan be discussed with and signed by all officers and crew involved before operations start?

  • A. So everyone understands the sequence, hazards, their responsibilities and the stop and emergency procedures
  • B. Because the terminal will not supply cargo otherwise
  • C. To satisfy the requirements of the bill of lading
  • D. So that only the chief officer needs to be present during operations
Answer: A — So everyone understands the sequence, hazards, their responsibilities and the stop and emergency procedures
Supervising personnel with cargo responsibilities includes briefing them on the plan, cargo hazards from the SDS, PPE, critical stages and emergency actions. A signed plan confirms understanding and supports safe handovers between watches.

18. What is the main reason for keeping cargo manifolds fitted with drip trays and the scuppers plugged during transfer?

  • A. To contain any leakage or spill on deck and prevent it going overboard
  • B. To collect rainwater for washing
  • C. To keep the deck dry for cargo sampling
  • D. To reduce static electricity
Answer: A — To contain any leakage or spill on deck and prevent it going overboard
Leakages are most likely at hose or arm connections. Drip trays under the manifold and plugged scuppers contain spills so they can be cleaned up and prevent pollution of the water, while spill equipment is kept ready near the manifold.

19. When connecting a cargo hose or reducer to the manifold, which practice is correct?

  • A. Use a gasket suitable for the cargo and fit bolts in every bolt hole, tightened evenly
  • B. Use any spare gasket available
  • C. Fit only half the bolts to allow quick disconnection
  • D. Use a rubber gasket for all cargoes
Answer: A — Use a gasket suitable for the cargo and fit bolts in every bolt hole, tightened evenly
The joint must be tight against the cargo and the agreed pressure. Gasket material must be compatible with the product, for example PTFE for many aggressive chemicals, and every bolt hole must be used with properly tightened bolts so the connection cannot leak.

20. During discharge, the terminal cannot accept cargo at the agreed rate and back pressure at the manifold rises. What should the ship do?

  • A. Reduce the pump rate to stay within the agreed maximum manifold pressure and consult the terminal
  • B. Increase the pump speed to overcome the back pressure
  • C. Close the manifold valve quickly while the pump runs
  • D. Open the manifold drain to relieve pressure
Answer: A — Reduce the pump rate to stay within the agreed maximum manifold pressure and consult the terminal
Exceeding the agreed manifold pressure can rupture hoses or arms. The ship must keep within the agreed pressure and rate, adjusting pump speed as necessary, and never close valves against a running pump, which would cause surge and pump damage.

21. Why is it important to record the times of starting and stopping cargo operations, rates, pressures and any stoppages during transfer?

  • A. They form the operational record needed for safety review, quantity disputes and statutory entries such as the Cargo Record Book
  • B. They are needed only for crew overtime
  • C. They are required only by the vessel's flag for ships over 20 years
  • D. They replace the ullage report
Answer: A — They form the operational record needed for safety review, quantity disputes and statutory entries such as the Cargo Record Book
Accurate cargo logs support investigation of incidents and claims, show compliance with agreed rates and pressures, and provide the information for Cargo Record Book entries, notices of protest and time sheets.

22. What is the safest method to clear cargo remaining in a deepwell pump discharge line at the end of discharge?

  • A. Use the pump's purging connection to blow the line to shore with nitrogen or air at controlled pressure
  • B. Open the line drain to deck
  • C. Leave the cargo in the line for the next voyage
  • D. Flush the line with seawater into the sea
Answer: A — Use the pump's purging connection to blow the line to shore with nitrogen or air at controlled pressure
Deepwell pumps are fitted with purging arrangements so that the riser and discharge line can be blown clear with nitrogen or compressed air towards the shore, completing discharge and reducing residues without releasing cargo on deck or overboard.

23. Before loading a cargo that requires the tank to be dry, which check is appropriate?

  • A. Confirm the tank, lines and pump are free of water and, if specified, measure the dew point of the tank atmosphere
  • B. Fill the tank with fresh water and then pump it out
  • C. Measure the cargo's flash point
  • D. Check the pH of the ballast water
Answer: A — Confirm the tank, lines and pump are free of water and, if specified, measure the dew point of the tank atmosphere
Water-sensitive cargoes require tanks and systems to be dried thoroughly, often by ventilating with dry air or nitrogen. Where 'Dry' is required in column h of chapter 17, the dew point of the inert or drying gas and tank atmosphere is checked to confirm moisture is low enough.

24. A tank's P/V valve is normally set for the venting system pressure. When a cargo requires a different setting or the vapour return line is used, what must the officer do before loading?

  • A. Confirm that the venting arrangement and settings for each tank meet the product's requirements and agree vapour pressure limits with the terminal
  • B. Close the P/V valve completely during loading
  • C. Open the tank ullage hatch for free venting
  • D. Remove the flame screens to increase venting capacity
Answer: A — Confirm that the venting arrangement and settings for each tank meet the product's requirements and agree vapour pressure limits with the terminal
The type of venting required for each product is given in column g of chapter 17. The officer must ensure the correct venting line-up, check P/V valves are free and correctly set, and when using vapour return agree the maximum loading rate and vapour pressure with the terminal.

25. What is the main hazard of loading a cargo into a tank containing residues of an incompatible previous cargo?

  • A. A dangerous reaction producing heat, gas or toxic products, as well as cargo contamination
  • B. Only a minor change in colour
  • C. Reduction in the ship's draught
  • D. Increase in the tank's design pressure
Answer: A — A dangerous reaction producing heat, gas or toxic products, as well as cargo contamination
Even small residues can react with a new cargo, for example an acid with an alkali or a monomer with a catalyst. Tanks, lines and pumps must be cleaned to the required standard and compatibility with the previous cargo checked when planning the next load.

26. Which reagent is used in the wall-wash chloride test, a white cloudiness indicating chlorides from seawater washing?

  • A. Silver nitrate solution
  • B. Potassium permanganate solution
  • C. Phenolphthalein indicator
  • D. Sodium hydroxide solution
Answer: A — Silver nitrate solution
In the chloride test, silver nitrate is added to the wall-wash sample; chloride ions form insoluble silver chloride, seen as white turbidity compared with a standard. The result shows whether seawater salt has been adequately removed by the fresh water rinse.

27. Which liquid is most commonly used as the wall-wash solvent when testing tank surfaces before loading a high-purity cargo?

  • A. High-purity methanol
  • B. Seawater
  • C. Diesel oil
  • D. Caustic soda solution
Answer: A — High-purity methanol
High-purity methanol is sprayed onto selected bulkhead areas and collected; it dissolves traces of previous cargo, hydrocarbons and chlorides. The sample is then tested for chlorides, hydrocarbons, colour and permanganate time against the specification for the next cargo.

28. In a wall-wash hydrocarbon (water miscibility) test, demineralised water is added to the methanol sample. What indicates the presence of hydrocarbons?

  • A. The mixture becomes cloudy or hazy
  • B. The mixture turns pink
  • C. Gas bubbles are given off
  • D. The mixture remains perfectly clear
Answer: A — The mixture becomes cloudy or hazy
Methanol is fully miscible with water, but hydrocarbons are not. If hydrocarbon residues are present, adding water causes them to come out of solution, producing turbidity that is compared with standards; a clear mixture indicates the tank meets the requirement.

29. Why is a final rinse with fresh or demineralised water given after washing a tank with seawater before loading a sensitive cargo?

  • A. To remove the chloride salts left by seawater, which cause wall-wash failure and pitting of stainless steel
  • B. To raise the temperature of the tank
  • C. To remove the tank coating
  • D. To inert the tank
Answer: A — To remove the chloride salts left by seawater, which cause wall-wash failure and pitting of stainless steel
Seawater leaves chloride residues on tank surfaces. These fail the chloride specification of many cargoes and attack the passive film on stainless steel. A fresh water rinse followed by drying removes the salts before inspection and wall-wash testing.

30. Which reference publication is widely used on chemical tankers for recommended tank cleaning procedures for each product?

  • A. Dr. Verwey's Tank Cleaning Guide
  • B. The IAMSAR Manual
  • C. The International Code of Signals
  • D. The Ship's Routeing guide
Answer: A — Dr. Verwey's Tank Cleaning Guide
The Tank Cleaning Guide by Dr. Verwey lists products with their properties and recommended cleaning methods, such as water temperature, use of detergents and whether a cold prewash is needed, and is used together with the P&A Manual and company procedures.

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