Technigaz Mark III system
LNG1032-100 :
A :
In which system is "Triplex" used to form the secondary barrier? Wrong or Missed Data? Click
36% nickel steel
LNG1032-101 :
A :
What is Invar? Wrong or Missed Data? Click
The tanks are of stiffened plate structure of either aluminium or 9% nickel steel. The tanks are sub-divided by a centre line liquid tight bulkhead and swash bulkheads dividing them into four spaces.
LNG1032-102 :
A :
What is the tank material and the tank structure of the SPB system developed by the Japanese company IHI? Wrong or Missed Data? Click
Vessels with Moss containment are instantly recognisable in that the tops of the spheres protrude above the hull. Vessels with Membrane containment have the characteristic whaleback/trunkdeck. Vessels with an SPB containment have a flat deck.
LNG1032-103 :
A :
How do you easily recognise LNG vessels with Moss, Membrane or SPB containment? Wrong or Missed Data? Click
-124°C
LNG1032-104 :
A :
What is the maximum temperature allowed at the equatorial ring on a Moss type vessel before loading can be started? Wrong or Missed Data? Click
On a Moss vessel the main requirement to keep the tanks ready for loading is to keep the equatorial ring cold. On a Membrane vessel the main requirement is to ensure that sufficient heel is retained from the previous discharge to keep the tank bottoms cold for the whole of the voyage to the loading port.
LNG1032-105 :
A :
What is the main requirement to keep the tanks ready for loading on a Moss vessel and on a Membrane vessel? Wrong or Missed Data? Click
By spraying LNG into the tank at regular intervals during the ballast voyage.
LNG1032-106 :
A :
How is the equatorial ring on a Moss vessel kept cold, ready for loading? Wrong or Missed Data? Click
It is the internal tank pressure that keeps the membrane pressed against the underlying load bearing insulation and so prevents any fatigue stresses due to the vessel's motion or vibration.
LNG1032-107 :
A :
Why is the tank pressure more critical on Membrane ships than Moss ships and why to maintain this pressure between design limits? Wrong or Missed Data? Click
Inert gas from the system's cooling tower passes through a separator where entrained water droplets are removed centrifugally. The saturated gas then enters a refrigerated cooler where it is dehumidified to a dew point of about 5°C. Thus a large amount of water is removed without causing it to freeze. From the cooler, the
LNG1032-108 :
A :
Briefly describes how the inert gas is dehumidified then dried in the inert gas plant. Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
2.Equipment (Module 2) - test for Chief Engineer
By using a small blower to circulate gas, heated by a steam or electric heater at the inlet of the column, and then passing it over a cooler at the outlet of the column to condense the moisture out of it.
LNG1032-109 :
A :
How is the desiccant in the drier unit of the inert gas plant regenerated after it has been depleted? Wrong or Missed Data? Click
Regeneration is deemed to be complete when the column outlet temperature is between 180-200°C.
LNG1032-110 :
A :
When do you know that the regeneration of the desiccant in the inert gas plant drier unit is completed? Wrong or Missed Data? Click
The regenerated column is ready for use when it has been cooled to between 40-45°C.
LNG1032-111 :
A :
When is the regenerated desiccant column of the inert gas plant drier unit ready for use? Wrong or Missed Data? Click
It is the temperature at which water in the atmosphere becomes saturated and condensation begins.
LNG1032-112 :
A :
What is the definition of Dew Point? Wrong or Missed Data? Click
5 to 9 hours which is around 60% - 70% of the time it takes to deplete a column.
LNG1032-113 :
A :
On average, how long does it normally take to regenerate a depleted desiccant column of the inert gas plant drier unit? Wrong or Missed Data? Click
A pressure control valve is located at the outlet of the drier unit to maintain a constant pressure throughout the system, thus ensuring a stable flame at the generator.
LNG1032-114 :
A :
What is the function of the pressure control valve located at the outlet of the drier unit? Wrong or Missed Data? Click
To operate the delivery valve to the deck main and the purge valve to atmosphere.
LNG1032-115 :
A :
Why to measure the Dew Point and Oxygen content of the inert gas produced? Wrong or Missed Data? Click
The inert gas system should be operated periodically for testing.
LNG1032-116 :
A :
How to make sure that the inert gas system operates correctly and can produce inert gas within operational limits? Wrong or Missed Data? Click
The quality of the inert gas depends on the fuel burnt, combustion efficiency and effectiveness of scrubbing arrangements.
LNG1032-117 :
A :
What can change the quality of the produced inert gas? Wrong or Missed Data? Click
2.Equipment (Module 2) - test for Chief Engineer
Inert gas is used for inerting and gas freeing of cargo tanks, pipelines and void spaces, prior to aerating, for maintenance and survey requirements.
LNG1032-118 :
A :
What is the use of Inert Gas on board? Wrong or Missed Data? Click
IG delivery to the deck main is only possible when oxygen is less than 0.5% (by volume) and the dew point is less than -45°C.
LNG1032-119 :
A :
What are the requirements for the inert gas plant regarding the oxygen content and the dew point? Wrong or Missed Data? Click
To clean the gas in the scrubbing tower. To pre-cool the gas before it enters the refrigerated cooler. To cool the combustion chamber.
LNG1032-120 :
A :
What is the purpose of the water supplied to the IG plant by the high capacity sea water pump? Wrong or Missed Data? Click
Flush out thoroughly with fresh water.
LNG1032-121 :
A :
After the inert gas plant has been stopped and the shutdown/cooling process has been completed, what should be done with the salt water side of the system prior to shutting down completely for a long period?
Wrong or Missed Data? Click
High water level in the cooling tower. High temperature in the cooling jacket. High sea water overboard temperature.
LNG1032-122 :
A :
Can you state 3 conditions that will trip and shut down the inert gas plant? Wrong or Missed Data? Click
Pressurisation/purging of barrier insulation spaces. Bulkhead seal gas for HD and LD compressors. Purging of various parts of the cargo piping and systems. Purging of piping related to boiler gas burning.
LNG1032-123 :
A :
What is nitrogen used for on LNG vessels? Wrong or Missed Data? Click
-196°C
LNG1032-124 :
A :
What is the temperature of liquid nitrogen at atmospheric pressure? Wrong or Missed Data? Click
3% Oxygen, -65°C Dew Point
LNG1032-125 :
A :
What would be the normal oxygen content and Dew Point of the nitrogen produced by a membrane nitrogen generator? Wrong or Missed Data? Click
The first few hours of cargo loading.
LNG1032-126 :
A :
During normal cargo operations when would you expect the greatest demand for nitrogen? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
2.Equipment (Module 2) - test for Chief Engineer
The liquid nitrogen is stored in double skinned tanks, the inner tank being made of "cold resistant" material, usually stainless steel. The space between the tanks is insulated with high efficiency insulation and is also under vacuum to reduce heat transfer to a minimum.
LNG1032-127 :
A :
What do you know about bulk liquid nitrogen storage tanks? Wrong or Missed Data? Click
Feed air temperature high. Air heater temperature high. Oxygen content high high.
LNG1032-128 :
A :
Can you state 3 conditions that will trip a nitrogen generator? Wrong or Missed Data? Click
-140°C to +20°C
LNG1032-129 :
A :
What is the temperature range that the vaporiser outlet can be set to in order to cover all its possible duties? Wrong or Missed Data? Click
Purging cargo tanks with vapour after inerting with inert gas and prior to cool down. Supplying gas to the cargo tanks when no gas is available from shore during a discharge. Liquid nitrogen vaporisation for inerting the cargo tanks and insulation spaces. Emergency force vaporising.
LNG1032-130 :
A :
What are the uses of the vaporiser on board? Wrong or Missed Data? Click
To ensure that the steam/condensate side of the vaporiser does not freeze up.
LNG1032-131 :
A :
Why must the vaporiser be thoroughly pre-heated with the steam valve full open before any LNG or liquid nitrogen is introduced? Wrong or Missed Data? Click
-140°C
LNG1032-132 :
A :
What temperature would the vaporiser outlet be set to when supplying gas to the cargo tanks during discharge if return gas is unavailable from shore?
Wrong or Missed Data? Click
High High condensate level trip. High vapour header pressure (set point 20 kPa). Low Low condensate temperature trip (set point 80°C).
LNG1032-133 :
A :
Can you state 3 conditions that would trip the vaporiser? Wrong or Missed Data? Click
LNG inlet valves only
LNG1032-134 :
A :
When the vaporiser trips, which valves are closed? Wrong or Missed Data? Click
Sending excess gas back ashore during cargo loading. Snding excess gas back ashore during cargo tank cool down. Circulating warm gas through the cargo tanks during warm-up operations.
LNG1032-135 :
A :
Can you state 3 uses of the HD compressor? Wrong or Missed Data? Click
2.Equipment (Module 2) - test for Chief Engineer
To prevent cold gas from flowing into the gear box and lubricating oil system. To prevent lubricating oil mist from entering the LNG gas stream. To prevent gas from escaping into the compressor house via the gear box vent.
LNG1032-136 :
A :
Why is nitrogen seal gas supplied to the compressor seals at a pressure higher than the gas suction pressure? Wrong or Missed Data? Click
If the compressor is driven by an electric motor, the motor is fitted in another room outside the gas zone and is driven by a shaft.
LNG1032-137 :
A :
What are the requirements if the HD compressor is driven by an electric motor? Wrong or Missed Data? Click
If the compressor is driven by a steam turbine, both compressor and turbine can be in the same room in the gas zone.
LNG1032-138 :
A :
What is the main advantage of having the HD compressor driven by a steam turbine? Wrong or Missed Data? Click
If the flow rate falls below the designed minimum preset ratio between gas flow and compressor differential pressure signals, the anti-surge controller produces a signal which modulates the compressor surge valve. If the flow rate is kept below this stated, designed minimum flow rate, the gas flow will not be stable. The compressor will surge, causing shaft vibration and possible damage to the compressor.
LNG1032-139 :
A :
What defines the minimum flow rate of the HD compressor? What happens if the flow rate is kept below this stated, designed minimum flow rate?
Wrong or Missed Data? Click
When two compressors are run in parallel, their load is usually increased by a common ramp up controller to maintain them in balance and prevent surging of one or both compressors.
LNG1032-140 :
A :
What is the problem when two compressors are run in parallel? What is the solution? Wrong or Missed Data? Click
During initial cargo loading the excess LNG vapour is free flowed ashore and the HD compressors are started in turn as required.
LNG1032-141 :
A :
What is the use of the HD compressor(s) at the initial phase of cargo loading? Wrong or Missed Data? Click
No
LNG1032-142 :
A :
Is it better to run two compressors on reduced load than one compressor on full load? Wrong or Missed Data? Click
The alarm in the cargo control room is accepted there but then it must also be accepted and reset locally in the compressor house.
LNG1032-143 :
A :
From where can alarms on the HD compressor be accepted and reset? Wrong or Missed Data? Click
To supply boil-off gas to the boilers.
LNG1032-144 :
A :
What are the LD compressors used for? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
2.Equipment (Module 2) - test for Chief Engineer
The boiler load, provided that the vapour header pressure is above a preset minimum value.
LNG1032-145 :
A :
What determines the output capacity of the LD compressor? Wrong or Missed Data? Click
In the engine control room.
LNG1032-146 :
A :
Where are the remote controllers for the LD compressors situated? Wrong or Missed Data? Click
Cargo tank pressure low. Low Low gas seal pressure. Low Low bulkhead seal pressure. High High gas discharge temperature.
LNG1032-147 :
A :
Can you state 4 conditions that will trip the LD compressor? Wrong or Missed Data? Click
Heating boil-off gas supplied to the main boilers either by free flow or via the LD compressors. Heating up LNG vapour which is then delivered to the HD compressors for warming up the cargo tanks prior to inerting.
LNG1032-148 :
A :
What is the use of the gas heaters? Wrong or Missed Data? Click
+80°C
LNG1032-149 :
A :
What is the maximum temperature the heater outlet would be set to for tank warming up operations? Wrong or Missed Data? Click
+20°C
LNG1032-150 :
A :
What temperature would the heater outlet normally be set to for supplying gas to the boilers? Wrong or Missed Data? Click
So that there is no possibility of freezing up the condensate side of the heater.
LNG1032-151 :
A :
Why should the heater be thoroughly warmed through before any LNG vapour is introduced to it? Wrong or Missed Data? Click
Condensate outlet temperature very low. Drain pot level very high. Gas outlet temperature very high.
LNG1032-152 :
A :
Can you give 3 situations that will cause the gas heater to trip? Wrong or Missed Data? Click
A small vaporiser used for vaporising LNG liquid to provide gas for burning in the boilers additional to the cargo's natural boil-off.
LNG1032-153 :
A :
What is a forcing vaporiser? Wrong or Missed Data? Click
2.Equipment (Module 2) - test for Chief Engineer
The vaporiser is installed upstream of the LD compressor with a mist separator at the mixing point with natural boil-off gas. The LNG is supplied by
spray/stripping pump and the flow is controlled by an automatic inlet feed valve which receives its signal from the boilers gas management system.
LNG1032-154 :
A :
Where is installed the forcing vaporiser? How is the LNG supplied to it? Wrong or Missed Data? Click
-30 to -40°C
LNG1032-155 :
A :
At what temperature is the gas outlet from the forcing vaporiser usually controlled? Wrong or Missed Data? Click
To ensure that any non-vaporised droplets of gas are either vaporised by mixing with the natural boil off gas or separated out prior to the gas going to the LD compressor.
LNG1032-156 :
A :
Why is a mist separator fitted downstream of the forcing vaporiser where the gas produced by the vaporiser mixes with the natural boil- off gas?
Wrong or Missed Data? Click
Low Low condensate temperature, set point 80°C. Vapour header pressure high, set point 20kPa (121.3kPaA). High High condensate level.
LNG1032-157 :
A :
Can you state 3 situations that will trip the forcing vaporiser? Wrong or Missed Data? Click
Two
LNG1032-158 :
A :
How many main cargo pumps are normally fitted in each tank of both Moss and Membrane type vessels? Wrong or Missed Data? Click
Partially open.
LNG1032-159 :
A :
What position should the discharge valve of a main cargo pump be in prior to starting the pump? Wrong or Missed Data? Click
By altering the position of the discharge valve.
LNG1032-160 :
A :
How is the discharge rate of a cargo pump controlled? Wrong or Missed Data? Click
Four times in one hour but after the third time a 30 minute waiting period is required before the next start.
LNG1032-161 :
A :
What is the maximum number of consecutive starts that can be carried out for a main cargo pump? Wrong or Missed Data? Click
It is more efficient and good operating practise to operate one main cargo pump at design flow rate rather than two pumps at 50% flow rate.
LNG1032-162 :
A :
What is the difference between operating one main cargo pump at 100% flow rate and two pumps at 50% flow rate? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
2.Equipment (Module 2) - test for Chief Engineer
Fluctuations in the discharge pressure and ammeter readings are an indication that the pump is starting to cavitate so the discharge valve should be shut in to stabilise conditions.
LNG1032-163 :
A :
How do you know that a cargo pump is cavitating? What would be your action in this case? Wrong or Missed Data? Click
Main cargo pumps can be test run when the pump is fully submerged in liquid.
LNG1032-164 :
A :
When can you test run a cargo pump? Wrong or Missed Data? Click
Low motor current. Motor single phase failure. Motor over current. Tank Low Low level.
LNG1032-165 :
A :
Can you state 4 conditions that will trip a cargo pump? Wrong or Missed Data? Click
Hydraulic pressure low. Control air pressure low. Cargo tank pressure below or equal to primary insulation space pressure plus 0.5 kPa. Vapour header below or equal to atmospheric pressure plus 0.3 kPa.
LNG1032-166 :
A :
Can you state 4 situations that will give an ESD and stop all cargo pumps? Wrong or Missed Data? Click
It must be completely isolated.
LNG1032-167 :
A :
What is the key requirement before any inspection or maintenance is undertaken on electrical equipment? Wrong or Missed Data? Click
Keeping records of resistance and continuity readings can help providing early indications of possible faults.
LNG1032-168 :
A :
What can help to provide early indications of possible electrical faults? Wrong or Missed Data? Click
Insulation resistance testing and recording of the pump cables and motors on all loaded voyages. Recording of pump amps, position of discharge valve, discharge pressure during bulk discharge to establish any trend. Routine inspection/cleaning of starter boxes, all connections to be clean and tight. Routine testing of all associated trips and alarm functions, using current injection and pressure calibrator test equipment as required.
LNG1032-169 :
A :
Can you give 4 procedures that would be considered good practice for in service maintenance and monitoring of pump performance? Wrong or Missed Data? Click
To cool down the cargo tanks by pumping LNG through the spray rails at the top of the tank. To cool down the liquid header prior to discharge. To pump LNG to the forcing vaporiser when additional gas is required for gas burning in the boilers.
LNG1032-170 :
A :
Can you give 3 procedures where stripping/spray pumps are used? Wrong or Missed Data? Click
One in each tank.
LNG1032-171 :
A :
How many stripping/spray pumps are normally fitted in an LNG carrier? Wrong or Missed Data? Click
2.Equipment (Module 2) - test for Chief Engineer
Single stage pump fitted with an inducer, driven by submerged electric motor
LNG1032-172 :
A :
What type of pump is the stripping/spray pump? Wrong or Missed Data? Click
10% open
LNG1032-173 :
A :
What state should the discharge valve be in prior to starting a stripping/spray pump? Wrong or Missed Data? Click
After the first main pump in the tank has been stopped and the liquid level is above the height of the stripping pump.