By pressurising the tank and transferring it to another empty tank.
LNG1032-460 :
A :
If both main cargo pumps fail in a fully loaded tank on a Moss type vessel how would the cargo be discharged? Wrong or Missed Data? Click
By fitting an emergency cargo pump into the tank.
LNG1032-461 :
A :
If both main cargo pumps fail in a fully loaded tank on a Membrane type vessel how would the cargo be discharged? Wrong or Missed Data? Click
By vaporising LNG in the vaporiser and supplying it to the top of the tank.
LNG1032-462 :
A :
How is the pressure created to enable the cargo to be transferred from one tank to another if both main cargo pumps in the tank have failed?
Wrong or Missed Data? Click
The pump sits in column in the tank and the pump discharges into the column which is fitted with a valve on the top connected to the liquid line.
LNG1032-463 :
A :
When an emergency pump is fitted into a tank how does it discharge into the liquid line? Wrong or Missed Data? Click
When the secondary barrier is +5°C
LNG1032-464 :
A :
On a membrane vessel when is warming up deemed to be complete? Wrong or Missed Data? Click
When the equator is above -20°C and tank wall approximately +5°C.
LNG1032-465 :
A :
On a Moss vessel when is warming up deemed to be complete? Wrong or Missed Data? Click
Less than 3% by volume
LNG1032-466 :
A :
How low does the concentration of methane have to be in all spaces and equipment before inerting is deemed to be complete? Wrong or Missed Data? Click
Level must be above 80% tank height or below a level equal to 10% of the tank length.
LNG1032-467 :
A :
What are the normal tank filling levels for a modern membrane type vessel so that it can proceed to sea without the risk of suffering severe sloshing damage?
Wrong or Missed Data? Click
Gas detection alarm in primary barrier space (PBS). Rise in pressure in affected PBS. Fall in temperature in bottom sensors in the secondary barrier space (SBS).
LNG1032-468 :
A :
What are the indications of a leak in the primary membrane? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
5.Non-standard and Emergency Operations (Module 5) - test for Cargo Engineer
Yes, it is a problem. A small amount of water in the secondary barrier can form ice and a thermal bridge to the inner hull resulting in a cold spot.
LNG1032-469 :
A :
In case of leakage into insulation spaces, is it a problem to have a small amount of water in the secondary barrier? Why? Wrong or Missed Data? Click
Bilge wells are fitted with water detection sensors and pumping out facilities at the bottom, after end of each secondary insulation space or hold space (Moss ships).
LNG1032-470 :
A :
How to detect and eliminate water in the secondary insulation space or hold space (Moss ships)? Wrong or Missed Data? Click
Large quantities of water leaking into the insulation space of a membrane vessel could severely damage the tank membranes and insulation boxes.
LNG1032-471 :
A :
What could happen in case of serious water leakage into the insulation space of a membrane vessel? Wrong or Missed Data? Click
When the primary insulation space is 3kPa lower than the secondary.
LNG1032-472 :
A :
At what differential pressure of primary and secondary barriers is it recommended that they are inter-connected to equalise the pressures?
Wrong or Missed Data? Click
- Cargo tank insulation spaces. - Gas burning operations. - Gas compressors. - Vent mast fire extinguishing system. The dry powder fire extinguishing stations on deck are not affected.
LNG1032-473 :
A :
If the nitrogen generating system failed on board an LNG carrier and no nitrogen was available, can you state 4 systems that would be affected? Are the dry powder fire extinguishing stations on deck affected?
Wrong or Missed Data? Click
There are four alarm stages for high level to help to prevent overflowing of tanks, usually: - 95% high alarm - 98% high high alarm - 98.5% alarm and tank filling valve close - 99% very high level alarm and ESD.
LNG1032-474 :
A :
What are the cargo tanks' high level alarm stages? Wrong or Missed Data? Click
If any equipment control system in the IAS fails, then it is possible to switch to manual local control and continue operations.
LNG1032-475 :
A :
The IAS system (Integrated Automation System) is a distributed processing system. The control functions are defined locally in the process stations and not in the operator stations. Why is it important in case of failure?
Wrong or Missed Data? Click
In the event of an LNG liquid leak during cargo operations the first priority is to protect the adjacent steel work by spraying with water either from a fire hose or using the IMO spray pump.
LNG1032-476 :
A :
What would be your first priority in the event of an LNG liquid leak during cargo operations? Wrong or Missed Data? Click
Because the tank is not designed for the high pressure required to transfer the liquid.
LNG1032-477 :
A :
Why do membrane tanks have to be able to fit emergency cargo pumps as opposed to transferring the cargo by tank pressurisation as on a Moss vessel?
5.Non-standard and Emergency Operations (Module 5) - test for Cargo Engineer
So that if, for whatever reason, the foot valve opens or has not closed properly while and the column cover is removed the pressure in the tank would not insufficient to force the cargo up and overflow out of the top of the column.
LNG1032-478 :
A :
Why is the tank pressure reduced to just above atmospheric prior to and during the fitting of an emergency cargo pump? Wrong or Missed Data? Click
The basic design of the tanks permits the pressure require for the transfer. In general it is a safer operation than fitting an emergency cargo pump. All the equipment required for the operation is already part of the ships normal equipment except of the two additional pilot valves for the safety valves adjustment. It is more cost effective as no emergency pump needs to be purchased and maintained.
LNG1032-479 :
A :
After failure of the tank pumps on a Moss vessel, why is it preferable to transfer cargo by pressurisation of the tank, as opposed to fitting an emergency pump?
Wrong or Missed Data? Click
It is essential that the tank to be entered has blanked or at least double shut off arrangements between all other tanks and systems that contain LNG or vapour.
LNG1032-480 :
A :
What is an essential requirement regarding the isolation of a gas free tank that needs to be entered for inspection? Wrong or Missed Data? Click
The tank should be continuously purged with dry air while it is opened up and work is being carried out.
LNG1032-481 :
A :
What is an essential requirement regarding the ventilation of a gas free tank where work is being carried out? Wrong or Missed Data? Click
While a single tank is being aerated (after warming it up and gas freeing) gas burning cannot be continued, as the vapour line is needed to vent the tank to the forward mast riser.
LNG1032-482 :
A :
What is the problem on older vessels when aerating a single gas free tank while the other tanks are still under LNG vapour? Wrong or Missed Data? Click
That fully effective communication is established and maintained throughout the whole operation.
LNG1032-483 :
A :
What is of crtitical importance at all times during all stages of a ship to ship transfer? Wrong or Missed Data? Click
Altering the vessel's course. Altering the vessel's speed. Altering the vessel's trim.
LNG1032-484 :
A :
If the ship is on passage in rough weather and severe sloshing can be heard in the cargo tanks, what can be done? Wrong or Missed Data? Click
Inform the buyer's representative and the terminal control and agree on a way forward and whether loading/discharge operations should be continued or not.
LNG1032-485 :
A :
If any key equipment becomes unavailable while the vessel is in port either loading or discharging what should be the first course of action?
Wrong or Missed Data? Click
Venting the boil off to atmosphere via a mast riser.
LNG1032-486 :
A :
Different vessels are fitted with various ways of dealing with the boil off from the LNG cargo. Which method is common to all vessels but should only be used as a last resort?
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
5.Non-standard and Emergency Operations (Module 5) - test for Cargo Engineer
The proportion of methane in the cargo will decrease.
LNG1032-487 :
A :
What changes are likely to occur in cargo composition during a loaded passage? Wrong or Missed Data? Click
6.6kV: - Main cargo pumps. - HD compressors. 440V: - LD compressors - spray pumps - stripping pumps - compressor house/motor room fans
LNG1032-488 :
A :
Can you give 2 equipments that will be driven by 6.6kV motors on a modern LNG vessel? And 2 equipments that will be driven by the low voltage 440V supply system?
Wrong or Missed Data? Click
- Electric motor room supply fans. - Cargo compressor room exhaust fans. - Glycol circulating pumps.
LNG1032-489 :
A :
Your vessel suffers a blackout while discharging cargo. Can you state 3 pieces of equipment that will restart automatically when power is restored?
Wrong or Missed Data? Click
A gas detection alarm in the annular space/IBS/primary insulation space.
LNG1032-490 :
A :
What is usually the first indication given that a leak has developed in the primary barrier? Wrong or Missed Data? Click
30% LFL
LNG1032-491 :
A :
At what gas concentration is the normal alarm point for the gas detection system? Wrong or Missed Data? Click
Drain pipes fitted with bursting discs, that rupture at cryogenic temperatures, are fitted from the upper skirt stiffener to the drip pan.
LNG1032-492 :
A :
If a leak developed in the upper half of a Moss tank, how does the LNG get down to the drip collection pan under the tank. Wrong or Missed Data? Click
A punch messenger is deployed that punches a hole in the primary membrane and insulation box top at the tank bottom so that the LNG can flow into the tank as it is being pumped out.
LNG1032-493 :
A :
How is LNG removed from the primary barrier of a No96 system while the tank is being pumped out so that it does not collapse the membrane into the tank?
Wrong or Missed Data? Click
Pumps or eductors are provided to remove any ballast water that may leak into hold spaces or secondary insulation spaces.
LNG1032-494 :
A :
How to remove any ballast water that may leak into hold spaces or secondary insulation spaces? Wrong or Missed Data? Click
After a leak has been repaired in the inner hull on a membrane vessel and the insulation space pumped out final drying is achieved by increasing the nitrogen flow through the space.
LNG1032-495 :
A :
After a leak has been repaired in the inner hull on a membrane vessel and the insulation space pumped out, how to achieve the final drying of the space?
5.Non-standard and Emergency Operations (Module 5) - test for Cargo Engineer
Water leakage detectors are fitted in all hold and secondary insulation spaces.
LNG1032-496 :
A :
What will help to detect any water ingress in the hold and secondary insulation spaces? Wrong or Missed Data? Click
At least two generators are fitted. Air supply can be taken from other systems and compressors. Critical spares are carried on board. Regular maintenance and testing is carried out.
LNG1032-497 :
A :
Since nitrogen is so critical to the safe operation of an LNG vessel what is done to reduce the risk of loosing supply? Wrong or Missed Data? Click
That depends on the temperature: methane vapour become lighter than air at -100°C
LNG1032-498 :
A :
Is methane vapour lighter or heavier than air? At what temperature does methane vapour become lighter than air? Wrong or Missed Data? Click
395°C
LNG1032-499 :
A :
What is the auto ignition temperature of methane? Wrong or Missed Data? Click
First loading after refit.
LNG1032-500 :
A :
How often are the cargo tank independent high (98.5%) and high high (99% ESD) alarms normally tested by actually transferring cargo to activate them?
Wrong or Missed Data? Click
Either a main cargo pump or a stripping pump can be used for transferring the cargo. A person should be standing by the filling valve of the tank being tested so that he can close it manually if necessary. A good eye should be kept on all other tank levels in case any valves are leaking.
LNG1032-501 :
A :
When testing at the first loading after refit the cargo tank independent high (98.5%) and high high (99% ESD) alarms by actually transferring cargo to activate them, what are the precautions taken?
Wrong or Missed Data? Click
Small cargo leaks can sometimes be stopped by using rags and water to form an ice seal over the leak.
LNG1032-502 :
A :
How is it sometimes possible to stop small cargo leaks? Wrong or Missed Data? Click
Any person dealing with an LNG leak of any description must wear appropriate protective clothing.
LNG1032-503 :
A :
What is the key precaution when dealing with an LNG leak, even a small one? Wrong or Missed Data? Click
In the case of a major LNG leak the ESD must be activated immediately.
LNG1032-504 :
A :
How to react in case of major LNG leak? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
5.Non-standard and Emergency Operations (Module 5) - test for Cargo Engineer
1) Initiate cargo shutdown (ESD). 2) Sound alarms/make emergency PA announcement, advising no smoking/naked lights and implementing Emergency action plan. 3) Establish source of leakage and isolate as much as possible. 4) Identify and treat casualty summoning medical assistance as required. 5) Provide copious amounts of water to the leakage area to minimise cold shock and brittle fracture. 6) Eliminate possible sources of ignition as much as possible, bearing in mind the location and extent of gas cloud and drift direction. If in port advise terminal, civil and port authorities of gas cloud.
LNG1032-505 :
A :
What actions would you take in the event of a cargo spillage or pipeline rupture, starting with the most important? Wrong or Missed Data? Click