IV. CONTRATOS NO LABORALES
9. EL CONTRATO A TIEMPO PARCIAL OBJETO DEL CONTRATO
Invar steel
LNG1032-338 :
A :
What delicate material is used in the construction of some membrane tanks? Wrong or Missed Data? Click
To prevent damage to the containment system.
LNG1032-339 :
A :
Why is it necessary to keep membrane tanks free of foreign objects? Wrong or Missed Data? Click
The tank seal and all associated pipework should be pressure tested to ensure there are no leaks.
LNG1032-340 :
A :
How to ensure that there are no leaks on the tank seal and all associated pipework? Wrong or Missed Data? Click
By tack welding or wire.
LNG1032-341 :
A :
How may bolts in cargo tanks be secured? Wrong or Missed Data? Click
The last man out of the tank prior to sealing.
LNG1032-342 :
A :
Who is responsible for the cleanliness of a tank after a refit? Wrong or Missed Data? Click
At or below - 45ºC.
LNG1032-343 :
A :
What is the accepted dew point temperature of air used to aerate tanks prior to inerting? Wrong or Missed Data? Click
Moisture in the tank atmosphere could lead to malfunction of equipment. Moisture could form corrosives if it combines with agents in inert gas.
LNG1032-344 :
A :
Why must moisture in the tank atmosphere be strictly avoided? Wrong or Missed Data? Click
Nitrogen Generating plant.
LNG1032-345 :
A :
How is inert gas for the insulation spaces produced? Wrong or Missed Data? Click
Annular space.
LNG1032-346 :
A :
In spherical tanks, what is the space between the cargo tank outer wall and the insulation known as? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
It is introduced at the bottom and evacuated at the top.
LNG1032-347 :
A :
How is dry air introduced/evacuated through a space during aeration? Wrong or Missed Data? Click
3 kPa
LNG1032-348 :
A :
To avoid damage, what is the maximum differential pressure that the secondary space can be above the primary space? Wrong or Missed Data? Click
Oxygen > 20% and dew point at - 45ºC or below.
LNG1032-349 :
A :
When providing dry air, what qualities are required? Wrong or Missed Data? Click
Dry Air or Inert Gas.
LNG1032-350 :
A :
With spherical tank construction, diurnal temperature effects can cause pressure variations in the hold spaces. What can be used to top up this space?
Wrong or Missed Data? Click
Because Inert Gas in the annular space can bleed into the hold space.
LNG1032-351 :
A :
Why is continuous aeration required during entry into hold spaces on spherical tank vessels? Wrong or Missed Data? Click
8kPa and - 1kPa
LNG1032-352 :
A :
With spherical tank vessels what are the normal operating pressure alarm settings? Wrong or Missed Data? Click
The Dew Point is the temperature to which air would have to cool (at constant pressure and water vapour content) in order to reach saturation (state at which air is holding the maximum amount of water vapour possible).
LNG1032-353 :
A :
Can you give a definition of the Dew Point? Wrong or Missed Data? Click
Saturation is the state at which air is holding the maximum amount of water vapour possible at the existing temperature and pressure.
LNG1032-354 :
A :
Can you give a definition of saturation of the air? Wrong or Missed Data? Click
- 20ºC or lower
LNG1032-355 :
A :
During aeration, at what dew point can operations be considered at completed? Wrong or Missed Data? Click
4.Standard Operations (Module 4) - test for Cargo Engineer
There is the possibility of an explosive atmosphere occurring.
LNG1032-356 :
A :
Why is it unsafe to introduce methane gas into a non-inerted tank? Wrong or Missed Data? Click
IG freezes at a higher temperature than methane.
LNG1032-357 :
A :
Why can IG produce a powder that might clog filters or corrosive products? Wrong or Missed Data? Click
It is not able to produce the required quantity of IG.
LNG1032-358 :
A :
In membrane vessels, why is the nitrogen generating plant not used for inerting cargo spaces? Wrong or Missed Data? Click
At or below that of the primary space.
LNG1032-359 :
A :
In membrane vessels, when the cargo containment system is out of service during nitrogen purging operations, pressure in the secondary insulation space should be maintained at which level?
Wrong or Missed Data? Click
Atmospheric temperature and pressure.
LNG1032-360 :
A :
In membrane vessels, when the cargo system is out of service during inerting, what can affect the pressure in the insulation spaces? Wrong or Missed Data? Click
Spherical tanks are self supporting.
LNG1032-361 :
A :
What is the difference between membrane and spherical tanks? Wrong or Missed Data? Click
To ensure dryness and corrosion protection.
LNG1032-362 :
A :
Why has it become common practice to allow a small flow of nitrogen through annular spaces? Wrong or Missed Data? Click
A semi-permeable membrane allows different gases to flow through it at different rates. As compressed air flows across the membranes contained in the system, oxygen, carbon dioxide and water vapour, contained in the air, pass through the membrane to the low pressure side more quickly than nitrogen.
LNG1032-363 :
A :
What is the principle of the semi-permeable membranes used in nitrogen generators? Wrong or Missed Data? Click
Oxygen content < 3% and -60ºC dew point
LNG1032-364 :
A :
What quality of N2 can nitrogen generators typically produce? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
Filling valves will open.
LNG1032-365 :
A :
If diurnal temperature cools and pressure falls what is the effect on the filling valve of membrane or annular spaces? Wrong or Missed Data? Click
Open the membrane space inlet valve by-pass.
LNG1032-366 :
A :
What can be done if there is a sudden fall in membrane space pressure e.g. during the initial stages of loading? Wrong or Missed Data? Click
Oxygen content is < 2% and dew point -40ºC.
LNG1032-367 :
A :
When is drying and inerting a space typically considered as completed? Wrong or Missed Data? Click
Reducing the dew point.
LNG1032-368 :
A :
What is the purpose of drying the air in a cargo tank? Wrong or Missed Data? Click
To ensure a safe atmosphere while gassing up, prior to loading cargo.
LNG1032-369 :
A :
What is the purpose of inerting a cargo tank? Wrong or Missed Data? Click
Light diesel oil.
LNG1032-370 :
A :
What is burned in IG systems during the production of inert gas? Wrong or Missed Data? Click
Sea water.
LNG1032-371 :
A :
In an inert gas generator, what medium provides cooling for the products of combustion? Wrong or Missed Data? Click
Sulphur oxides.
LNG1032-372 :
A :
In an inert gas generator what component of the products of combustion is reduced in the cooling/washing tower? Wrong or Missed Data? Click
By the use of a demister.
LNG1032-373 :
A :
How is carry over of water droplets in the IG prevented? Wrong or Missed Data? Click
4.Standard Operations (Module 4) - test for Cargo Engineer
Efficient combustion and operation of the IG generator is ensured by the control of a pressure valve fitted at the outlet of the plant. After the pressure control valve, the output divides into a purge line up the vessel's funnel and the delivery line to the IG system. When the oxygen content of the produced gas is below 0.5% the delivery valve can be opened and the purge valve closed.
LNG1032-374 :
A :
What is the role of the pressure valve fitted at the outlet of the IG plant? What is the role of the delivery valve and the purge valve installed after this pressure valve?
Wrong or Missed Data? Click
It maximises the layer effect.
LNG1032-375 :
A :
What is the purpose of venting tanks in parallel and controlling the exhausted air release rate? Wrong or Missed Data? Click
No.
LNG1032-376 :
A :
Can inert gas support life? Wrong or Missed Data? Click
The cargo lines are joined using a "U" bend at the manifold.
LNG1032-377 :
A :
What operation is sometimes carried out in order to inert all cargo lines more easily? Wrong or Missed Data? Click
Yes.
LNG1032-378 :
A :
Is it necessary to inert small pipework in the cargo spaces? Wrong or Missed Data? Click
To ensure that good communications are maintained.
LNG1032-379 :
A :
Besides ensuring that ship and shore facilities are compatible, what is a major purpose of the Safety Check List? Wrong or Missed Data? Click
ICS
LNG1032-380 :
A :
What is the name of the international body whose Check Lists attempt to ensure that the same high standards are maintained world wide?
Wrong or Missed Data? Click
Senior representatives from ship and shore.
LNG1032-381 :
A :
Who would normally attend a pre-discharge meeting? Wrong or Missed Data? Click
Oxygen content <1% and dew point at or below -45ºC
LNG1032-382 :
A :
Except after a refit, what condition should the manifold be in on arrival at loading port? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
Soapy water
LNG1032-383 :
A :
After connection of the loading arms what substance is widely used to test the seal? Wrong or Missed Data? Click
Untoward movement of the vessel.
LNG1032-384 :
A :
What would cause an ESDS 2? Wrong or Missed Data? Click
To protect the loading arms.
LNG1032-385 :
A :
What is the purpose of an ESDS2? Wrong or Missed Data? Click
The PERC (Powered Emergency Release Couplings) ensures minimal spillage in the event of an emergency.
LNG1032-386 :
A :
What is the function of the PERC? Wrong or Missed Data? Click
With the cone pointing in the direction of cargo flow.
LNG1032-387 :
A :
How should filters be inserted into a manifold connection? Wrong or Missed Data? Click
Displacing inert gas with methane gas
LNG1032-388 :
A :
What is meant by "purging" cargo spaces? Wrong or Missed Data? Click
Cargo vaporiser.
LNG1032-389 :
A :
What unit is used on board to help produce sufficient quantities of methane gas for purging? Wrong or Missed Data? Click
Through the stripping/spray line.
LNG1032-390 :
A :
When alongside, how is liquid initially supplied to the vessel to assist purging? Wrong or Missed Data? Click
To avoid thermal shocks and vapour locks.
LNG1032-391 :
A :
Why is it important to ensure that careful control of the liquid supply is maintained during the initial stages of purging? Wrong or Missed Data? Click
4.Standard Operations (Module 4) - test for Cargo Engineer
To atmosphere until vented gas is at shore levels then it is sent to shore.
LNG1032-392 :
A :
Where is purged inert gas vented to? Wrong or Missed Data? Click
20ºC to 25ºC
LNG1032-393 :
A :
What should be the outlet temperature of the vaporiser? Wrong or Missed Data? Click
When purging, methane is introduced into the top of the tank to displace the IG because it is lighter than IG.
LNG1032-394 :
A :
Where to introduce the methane gas when purging, and why? Wrong or Missed Data? Click
The procedures that should be followed are those laid down by the vessel's builders in the vessel's cargo manual.
LNG1032-395 :
A :
Where to find information on the procedures that should be followed for purging? Wrong or Missed Data? Click
Cool down is the procedure which brings the cargo tank from a warm, purged atmosphere to a cooled condition that will allow the introduction of liquid gas. This is achieved by pumping LNG through the spray rail at the top of the tank, eventually cooling the tank and allowing the introduction of liquid into the bottom of the tank.
LNG1032-396 :
A :
What is the cooling down procedure? Wrong or Missed Data? Click
No. The vertical temperature difference is not as critical in membrane tanks as it is in those of rigid construction.
LNG1032-397 :
A :
Do the membrane tanks and tanks of rigid construction have the same requirements for the vertical temperature difference? Wrong or Missed Data? Click
Equatorial region
LNG1032-398 :
A :
What is the name given to the "mid range" region of a spherical tank? Wrong or Missed Data? Click
-130ºC
LNG1032-399 :
A :
What tank bottom temperature is required for membrane tanks before consideration is given to supply liquid and start loading proper? Wrong or Missed Data? Click
-115ºC
LNG1032-400 :
A :
What is the typical equatorial temperature of spherical tanks before commencing loading proper? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
Excess gas is sent to shore using the compressors.
LNG1032-401 :
A :
How is pressure in the tanks controlled during loading operations? Wrong or Missed Data? Click
In some membrane tanks spray rails are located around the side of the tank and in spherical tanks they are suspended from the centre column.
LNG1032-402 :
A :
What could be a difference in the location of the spray rails between membrane tanks and spherical tanks? Wrong or Missed Data? Click
Initially 20ºC/hr reducing to about 12ºC/hr
LNG1032-403 :
A :
What is the cool down rate for membrane tanks? Wrong or Missed Data? Click
Approx 9ºC/hr
LNG1032-404 :
A :
What is the cool down rate for spherical tanks? Wrong or Missed Data? Click
Insulation space pressure.
LNG1032-405 :
A :
What needs to be especially monitored at the start of cooldown/loading operations in membrane tanks? Wrong or Missed Data? Click
Open the space inlet bypass valve.
LNG1032-406 :
A :
What may be done in certain vessel types in order to overcome pressure problems in hold spaces and insulation spaces? Wrong or Missed Data? Click
By the custody transfer system in the control room.
LNG1032-407 :
A :
How is cargo condition monitored? Wrong or Missed Data? Click
- Membrane tank bottom temperature before loading: -130ºC - Spherical tank equatorial temperature before loading: -115ºC - Membrane tank liquid temperature after loading: -160ºC - Tank vapour temperature after loading: -158ºC
LNG1032-408 :
A :
What are the expected temperatures for: - Membrane tank bottom temperature before loading - Spherical tank equatorial temperature before loading - Membrane tank liquid temperature after loading - Tank vapour temperature after loading
Wrong or Missed Data? Click
The ability to control tank pressure.
LNG1032-409 :
A :
What factor will normally determine how quickly cargo can be loaded? Wrong or Missed Data? Click
4.Standard Operations (Module 4) - test for Cargo Engineer
To prevent pressure build up as the lines warm up.
LNG1032-410 :
A :
Why are tank valves left partially open on completion of loading? Wrong or Missed Data? Click
The free surface effect.
LNG1032-411 :
A :
What phenomenon needs to be taken into consideration at the latter stages of ballast operations? Wrong or Missed Data? Click
Trimmed even keel.
LNG1032-412 :
A :
What condition should the vessel be in at the completion of loading? Wrong or Missed Data? Click
Cargo loaded is maximised.
LNG1032-413 :
A :
What is the advantage of keeping tank loading pressure as low as possible? Wrong or Missed Data? Click
Cargo leakage.
LNG1032-414 :
A :
What problem would unexpected temperature and pressure changes in membrane and hold spaces suggest? Wrong or Missed Data? Click
In the event of membrane or hold space cargo leakage a gas detection alarm would usually confirm this situation
LNG1032-415 :
A :
In the event of membrane or hold space cargo leakage, unexpected temperature and pressure changes in membrane and hold spaces will happen. What would usually confirm the leakage?
Wrong or Missed Data? Click
Manual and left open.
LNG1032-416 :
A :
In what mode should be the loading valve of the final tank to be loaded? Wrong or Missed Data? Click
The relative value of gas to bunker fuel is making the practice of burning boil off gas much less common.
LNG1032-417 :
A :
What is the economic reason explaining the development of alternative propulsion systems (i.e. not a steam turbine) on LNG tankers? Wrong or Missed Data? Click
During tank draining.
LNG1032-418 :
A :
At what stage in de-ballasting operations does free surface effect need to be taken into consideration? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
1 to 600.
LNG1032-419 :
A :
Closing a line with liquid entrapped will lead to over-pressurisation. What rate of expansion can be encountered from liquid to vapour? Wrong or Missed Data? Click
Through the loading arm cooldown valve.
LNG1032-420 :
A :
How can liquid which remains outboard of the ship's valve be displaced? Wrong or Missed Data? Click
The pressure no longer rises.
LNG1032-421 :
A :
How can you check that there is no more liquid remaining in the line outboard of the ship's valve? Wrong or Missed Data? Click
< 2%
LNG1032-422 :
A :
After purging with nitrogen, what methane content must be achieved in the loading arm before it can be disconnected? Wrong or Missed Data? Click
Venting it to atmosphere.
LNG1032-423 :
A :
Which method is not normally acceptable for controlling excess boil off gas? Wrong or Missed Data? Click
Re-liquefaction plant.
LNG1032-424 :
A :
What equipment is fitted to some newer vessels to control excess boil off gas? Wrong or Missed Data? Click
Because the lighter methane components evaporate first.
LNG1032-425 :
A :
Why can the cooling effect of cargo heel be reduced? Wrong or Missed Data? Click
Closed and in manual.
LNG1032-426 :
A :
What condition does the terminal require manifold valves to be in on arrival at the discharge port? Wrong or Missed Data? Click
It provides vapour from shore to fill the vacated space left by the discharged liquid cargo.
LNG1032-427 :
A :
What is the purpose of connecting a vapour return line during cargo discharge operations? Wrong or Missed Data? Click
4.Standard Operations (Module 4) - test for Cargo Engineer
Nitrogen.
LNG1032-428 :
A :
What is used to pressurise and leak test loading arms? Wrong or Missed Data? Click
A cargo pump is circulated with the discharge valve partially open, once the shore advises cool down is complete, discharge is controlled using the discharge valve.
LNG1032-429 :
A :
How do you start the discharge operations? Wrong or Missed Data? Click
They are approved by customs for cargo measurement.
LNG1032-430 :
A :
What makes a Custody Transfer System (CTS) specifically different from other measurement systems? Wrong or Missed Data? Click
This CTS system consists of level and temperature sensors with pressure sensors near the tank dome. It is made up of a number of capacitance type segments, incorporating level sensors with high and very high level alarms which are connected to the emergency valve closing system. Liquid level is determined by detecting the number of completely submerged segments and measuring the level in the segment which intercepts the liquid surface.
LNG1032-431 :
A :
Describe the Custody Transfer System (CTS) based on capacitance sensors. Wrong or Missed Data? Click
0.2ºC
LNG1032-432 :
A :
What accuracy can typically be expected for temperature sensors? Wrong or Missed Data? Click
An intrinsically safe barrier.
LNG1032-433 :
A :
What do all electrical circuits connected to equipment in a cargo tank pass through? Wrong or Missed Data? Click
Float type level gauges are fitted as back up to electrical systems.
LNG1032-434 :
A :
What is the use of float type level gauges on the modern LNG tankers? Wrong or Missed Data? Click
All but the upper part of the top segment.
LNG1032-435 :
A :
Prior to discharge, how much of the tank sensors would you expect to be submerged? Wrong or Missed Data? Click
Cargo heel is used to keep tanks cool prior to loading.
LNG1032-436 :
A :
What is the use of the cargo heel? Wrong or Missed Data? Click
Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)
4.Standard Operations (Module 4) - test for Cargo Engineer
Spherical tanks normally have a stripping pump which can be used to cool down lines prior to discharge.
LNG1032-437 :
A :
How to cool down the lines prior to discharge on a tanker with spherical tanks?