Videotel Cbt Lng 1032 Q&A v100

Videotel CBT LNG Vers 1.0.32 (QUESTIONS & CORRECT ANSWERS)Navigare necesse est !

Function onboard : Cargo Engineer1.Fundamental Knowledge and Understanding (Module 1) - test for Cargo Engineer

-160.0

LNG1032-1 :

A :

Methane (LNG) cannot be liquefied by pressure alone and must be carried at its atmospheric boiling point. What is approximately thetemperature of this atmospheric boiling point?

Wrong or Missed Data? Click

The ENTROPY PRINCIPLE stating that the entropy of an isolated system not in equilibrium will tend to increase over time. Entropy is a measure of the spontaneousdispersal of energy at a given temperature. This principle explains why HEAT ALWAYS FLOWS FROM A HOT BODY TO A COOLER ONE.

LNG1032-10 :

A :

What is the second law of thermodynamics?


The temperature falls.

LNG1032-11 :

A :

When a gas flows through a nozzle, what happens to the temperature?


CO2 - carbon dioxide

LNG1032-12 :

A :

Which of the gases also present in Natural Gas must be removed as it is incondensable at the carriage temperature of LNG?


Displacement

LNG1032-13 :

A :

Which is the most widely used method of inerting on LNG carriers?


0.05

LNG1032-14 :

A :

What is the maximum oxygen content normally permitted in the tanks after inerting?


Less than -40C

LNG1032-15 :

A :

What should be the dew point of the inert gas?


100 ppm

LNG1032-16 :

A :

What should be the maximum carbon monoxide content of the inert gas?


Water vapour in the tanks will contaminate the cargo and cause corrosion.

LNG1032-17 :

A :

Why is the dew point of the inert gas significant?


of 335 Page 1 Version 1.0.0 , 2015 Adrian MINCULESCU


1.Fundamental Knowledge and Understanding (Module 1) - test for Cargo Engineer

- Conduction - Convection - Radiation

LNG1032-18 :

A :

What are the means of heat transfer?


A pressure gradient.

LNG1032-19 :

A :

What does require a forced convection?


Methane

LNG1032-2 :

A :

What is the principal constituent of LNG?


The warm air rises by convection.

LNG1032-20 :

A :

Gives an example of convection.


-55C

LNG1032-21 :

A :

What is the practical minimum temperature that special steel alloys can reach before they become brittle?


The "secondary barrier" retains the cargo and protects the hull from brittle fracture in the event of tank failure.

LNG1032-22 :

A :

Which problem the secondary barrier is intended to protect the hull against?


Yes

LNG1032-23 :

A :

Is mild steel affected by the leakage of cold liquefied gas?


Yes.

LNG1032-24 :

A :

Are independent Tank Type B ships permitted to have only a partial secondary barrier?


The circulation of nitrogen through the interbarrier spaces.

LNG1032-25 :

A :

What does require the GTT integral membrane designs for LNG carriers in relation to the interbarrier spaces?





For up to 10 days.

LNG1032-26 :

A :

How many days should the secondary barrier provide temporary containment of any envisaged cargo leakage?


The strength of the double hull.

LNG1032-27 :

A :

What are using integral membrane tanks to support the mass of the cargo?


No.

LNG1032-28 :

A :

Does the IGC Code define the operating procedures for LNG carriers?


Yes

LNG1032-29 :

A :

Is it true that the main Class Societies have incorporated the requirements of the IGC Code into their Rules?


600.0

LNG1032-3 :

A :

When one volume of Liquefied Natural Gas (LNG) evaporates, roughly how many volumes of gas will be produced?Wrong or Missed Data? Click

The Flag States.

LNG1032-30 :

A :

Who has the primarily responsibility to enforce compliance with the IMO Codes and Conventions?


A liquid with a vapour pressure exceeding 2.8 bar (absolute pressure) at 37.8C

LNG1032-31 :

A :

What is the IMO definition of a liquefied gas carried by sea?


Five years, with annual periodic re-inspection

LNG1032-32 :

A :

What is the validity of an International Certificate of Fitness for Carriage of Liquefied Gases?


32Celsius

LNG1032-33 :

A :

With regard to the carriage of liquefied gases, what is assumed to be the maximum temperature for sea water?





A 2G type ship.

LNG1032-34 :

A :

With respect to ship survival capability, what is the type of a ship intended to transport LNG which requires significant preventivemeasures to preclude its escape?


- intrinsically safe - flameproof

LNG1032-35 :

A :

What are the most commonly used principles of electrical safety in hazardous areas?


30.0

LNG1032-36 :

A :

How many changes of air volume per hour are required in motor rooms?


Alarm at 30% LFL Trip at 60% LFL

LNG1032-37 :

A :

For burning boil-off gas in LNG ships, what set points are required for the gas detection equipment fitted to the gas burning equipmentenclosure?


The International Chamber of Shipping (ICS)

LNG1032-38 :

A :

Who publishes the Tanker Safety Guide (Liquefied Gas)?Wrong or Missed Data? Click

Safety Management System

LNG1032-39 :

A :

In the context of the ISM Code, what does the SMS stand for?


Enthalpy

LNG1032-4 :

A :

What is the term used to define the total heat content of a gas?


Vetting

LNG1032-40 :

A :

What procedure, usually initiated by the charterer, is becoming an increasingly common requirement in selecting a ship?


5.3 14%

LNG1032-41 :

A :

What is approximately the flammability range of methane in air?





Purging

LNG1032-42 :

A :

What is the process used to remove hydrocarbon gases before air is introduced to a tank?


The Charpy V-notch test uses a standard sample with a specified V-shaped notch whose geometry is designed to raise stress levels at the tip. The sample is thencooled slightly below the intended minimum operating temperature and is hit by a pendulum or similar device to see how much energy is absorbed before the testpiece breaks.

LNG1032-43 :

A :

What is the Charpy V-notch test?


The Cargo Operations Manual

LNG1032-44 :

A :

Where would you find information about tank cooling rates to avoid the risk of shock-cooling?


The IGC Code

LNG1032-45 :

A :

Where would you find information about the gas carrier construction materials to be used in plates and pipes etc?


- Tungsten Inert Gas welding - Metal Inert Gas welding

LNG1032-46 :

A :

Which methods are suitable for welding aluminium alloys?


The MFAG (Medical First Aid Guide)

LNG1032-47 :

A :

Which publication contains details concerning first aid and the administration of antidotes?


The Cargo Data Sheets.

LNG1032-48 :

A :

Which document would contain the procedures to be followed in the event of an emergency involving cargo spillage?


The Auto Ignition Temperature

LNG1032-49 :

A :

What is the term for the temperature at which burning is caused by spontaneous ignition, that is, without the addition of external heat?


Enthalpy and Absolute Pressure

LNG1032-5 :

A :

A Mollier chart is used to understand what may happen when cargo gases are liquefied or condensed. Which properties does the Mollierchart plot?





0.208

LNG1032-50 :

A :

What is the safe minimum oxygen content for entry into an enclosed space?


- Mobile telephones: unsafe - Hearing aids: safe - Heart pacemakers: safe - Electric wrist watches: safe

LNG1032-51 :

A :

Only intrinsically safe and explosion-proof equipment should be used within the gas hazardous area. Which of the following items areconsidered safe to use under these circumstances? - Mobile telephones - Hearing aids - Heart pacemakers - Electric wrist watches


Fuel, air and heat source

LNG1032-52 :

A :

What are the three elements found in the Fire Triangle?


- Rapid pulse rate - Nausea and vomiting - Severe headaches - Burning or itching sensations

LNG1032-53 :

A :

Which symptoms indicate the inhalation of toxic vapour?


Suitable protective equipment including eye protection.

LNG1032-54 :

A :

What shoud wear crew members engaged in LNG cargo handling operations?


Poisoning by swallowing

LNG1032-55 :

A :

In the context of dangerous cargoes like LNG, what could result from ingestion?


Severe pain.

LNG1032-56 :

A :

Exposure to LNG can cause freezing of the flesh. What will cause re-warming?


Isolating the source of leakage

LNG1032-57 :

A :

What is the best method of tackling liquefied gas fires?


Dry powder breaks the chemical reaction of the fire.

LNG1032-58 :

A :

How does dry power put out a gas fire?





No.

LNG1032-59 :

A :

Is it true that dry powder will not damage electrical or electronic equipment?


SVP (Saturated Vapour Pressure)

LNG1032-6 :

A :

What is the correct name for the pressure exerted by the boiling liquid vapour of a gas within a closed container at a given temperature?


Only a low cooling effect.

LNG1032-60 :

A :

What is the cooling effect of dry power?


High expansion foam is only suitable for confined, liquid pool fires.

LNG1032-61 :

A :

For what is suitable high expansion foam in fighting LNG fires?


The intense heat of LNG fires means that water sprays must be used for cooling the ships structure.

LNG1032-62 :

A :

Why are water sprays used in fighting LNG fires?


No.

LNG1032-63 :

A :

Is it correct that the white vapour cloud formed by the escaping gas clearly indicates the flammable area?


10 litres per min per square meter.

LNG1032-64 :

A :

The fixed water spray system is required to protect structures and equipment. What is the volume of water required per square metre ofhorizontal surface?


It must be possible to start the pumps supplying the water spray system remotely.

LNG1032-65 :

A :

What is an important requirement for the pumps supplying the water spray system, except their capacity?


To minimise the quantity of cargo spilled.

LNG1032-66 :

A :

Why is the prompt operation of the ESD system so vital?





Never.

LNG1032-67 :

A :

Can you direct water jets into burning liquid gas?Wrong or Missed Data? Click

- The weather conditions at the time are critical to the successful outcome. - Ships course and speed should be adjusted to keep gas clouds clear of the deck andaccommodation. - Navigational warnings may have to be issued to alert other vessels in the

LNG1032-68 :

A :

What are key items to consider for a controlled release of liquid and/or vapour?


- planning all cargo operations carefully. - ensuring that the planned maintenance is carried out as scheduled. - ensuring everyone is properly trained for their duties.

LNG1032-69 :

A :

How to minimise emissions of LNG?


The Critical Temperature is the highest temperature a gas can have while still capable of being condensed by the application of pressure. The Critical Temperature isnot in the ambient range for methane.

LNG1032-7 :

A :

What is the Critical Temperature? Is this temperature in the ambient range for methane?


To identify, assess and manage risks so as to reduce the chances of an incident.

LNG1032-70 :

A :

What is the main purpose of risk assessment?


A potential to threaten human life, health, property or the environment.

LNG1032-71 :

A :

What is the meaning of the word hazard?


It is a combination of two factors the likelihood of something happening and the severity of the consequences if it does.

LNG1032-72 :

A :

What is the definition of risk?


1. Classify work activities 2. Identify all hazards 3. Determine risks 4. Decide if risk is acceptable 5. Plan action 6. Review and re-assess if necessary

LNG1032-73 :

A :

Systematic risk assessment involves six steps. What are they?


- It is systematic. There is a step by step technique. - It is about prevention rather than cure. - It encourages awareness of hazards and the risks they pose. - Notall risks can be predicted, selection of the appropriate ones is the key.

LNG1032-74 :

A :

What are the principles of risk assessment?





- A hazardous atmosphere - Extremes of temperature - Fire and explosion

LNG1032-75 :

A :

Which hazards might you encounter on an LNG carrier?


Yes

LNG1032-76 :

A :

Is it true that a risk can be considered tolerable if it has been reduced to the lowest level reasonably practicable?


No

LNG1032-77 :

A :

Is it true that moderate risks do not require specific efforts to reduce them?


Yourself, and you are also responsible for the safety of the other crew members.

LNG1032-78 :

A :

Who is responsible for your personal safety on board?


The greatest risks result from complacency and oversight. Management should contribute towards reducing this risk by establishing proper procedures for training,and by promoting safety consciousness on board. Each crew member should make sure that appliances are fit for the work to be undertaken. Accidents should bereported and each event regarded as an opportunity to strengthen an existing safety management system.

LNG1032-79 :

A :

What causes the greatest risks? What are the management responsibilities about risks? What are the crew members responsibilitiesabout risks?


At constant pressure, V/T = constant (i.e. as the temperature increases the volume increases)

LNG1032-8 :

A :

What is Charles Law?


Any appropriate, specific familiarisation training they require.

LNG1032-80 :

A :

What should receive personnel joining the vessel?Wrong or Missed Data? Click

If you supervise the work of other crew members you must check regularly that they are carrying out their duties fully and correctly.

LNG1032-81 :

A :

What are your responsabilities if you supervise the work of other crew members?


- be achievable. - have a clear trigger for instigation. - address the problem in a timely, effective and consistent manner.

LNG1032-82 :

A :

What are the main priorities for contingency plans?





Regularly

LNG1032-83 :

A :

When shoud contingency plans reviewed?


- The type of cargo and its disposition - Stability information - Location of fire fighting equipment, manuals and plans - Location of safety equipment

LNG1032-84 :

A :

What information should be readily available in an emergency?


Drills must be frequent and realistic. They must ensure that all who are responsible for them can satisfactorily operate the emergency equipment. Drills should beheld in all parts of the tanker and with different scenarios. De-briefings are an important part of any drill and should include all those involved.

LNG1032-85 :

A :

What are the main objectives of the safety drills?Wrong or Missed Data? Click

Yes.

LNG1032-86 :

A :

Is it true that falsifying records concerned with environmental pollution may be regarded as a criminal offence?


No.

LNG1032-87 :

A :

Is it true that minor errors in the records are not important as long as you can explain why they occurred?


The Second Officer

LNG1032-88 :

A :

Who would normally keep the records concerned with navigation?


2 years

LNG1032-89 :

A :

For how long must the Garbage Record Book be kept on board after the last date of entry?


P x V = n x R x T

LNG1032-9 :

A :

The general gas equation combines the gas laws with Avogadros hypothesis to give which formula?


1. Appraisal 2. Planning 3. Execution 4. Monitoring

LNG1032-90 :

A :

All plans involves four stages. What are they?




2.Equipment (Module 2) - test for Cargo Engineer

Technigaz Mark III system

LNG1032-100 :

A :

In which system is "Triplex" used to form the secondary barrier?


36% nickel steel

LNG1032-101 :

A :

What is Invar?


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 bulkheadsdividing 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?


Vessels with Moss containment are instantly recognisable in that the tops of the spheres protrude above the hull. Vessels with Membrane containment have thecharacteristic 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?


-124C

LNG1032-104 :

A :

What is the maximum temperature allowed at the equatorial ring on a Moss type vessel before loading can be started?


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 toensure 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?


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?


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 thevessel'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?


Inert gas from the system's cooling tower passes through a separator where entrained water droplets are removed centrifugally. The saturated gas then enters arefrigerated cooler where it is dehumidified to a dew point of about 5C. Thus a large amount of water is removed without causing it to freeze. From the cooler, thegas is further dried as it passes to a desiccant dehumidifier plant arranged in two units, one of which is in use while the other is being regenerated.

LNG1032-108 :

A :

Briefly describes how the inert gas is dehumidified then dried in the inert gas plant.





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 tocondense 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?


Regeneration is deemed to be complete when the column outlet temperature is between 180-200C.

LNG1032-110 :

A :

When do you know that the regeneration of the desiccant in the inert gas plant drier unit is completed?


The regenerated column is ready for use when it has been cooled to between 40-45C.

LNG1032-111 :

A :

When is the regenerated desiccant column of the inert gas plant drier unit ready for use?


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?


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?


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?


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?


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?


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?





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?


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 -45C.

LNG1032-119 :

A :

What are the requirements for the inert gas plant regarding the oxygen content and the dew point?


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?


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 saltwater side of the system prior to shutting down completely for a long period?


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?


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?


-196C

LNG1032-124 :

A :

What is the temperature of liquid nitrogen at atmospheric pressure?


3% Oxygen, -65C Dew Point

LNG1032-125 :

A :

What would be the normal oxygen content and Dew Point of the nitrogen produced by a membrane nitrogen generator?


The first few hours of cargo loading.

LNG1032-126 :

A :

During normal cargo operations when would you expect the greatest demand for nitrogen?





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 isinsulated 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?


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?


-140C to +20C

LNG1032-129 :

A :

What is the temperature range that the vaporiser outlet can be set to in order to cover all its possible duties?


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 adischarge. 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?


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?


-140C

LNG1032-132 :

A :

What temperature would the vaporiser outlet be set to when supplying gas to the cargo tanks during discharge if return gas isunavailable from shore?


High High condensate level trip. High vapour header pressure (set point 20 kPa). Low Low condensate temperature trip (set point 80C).

LNG1032-133 :

A :

Can you state 3 conditions that would trip the vaporiser?


LNG inlet valves only

LNG1032-134 :

A :

When the vaporiser trips, which valves are closed?


Sending excess gas back ashore during cargo loading. Snding excess gas back ashore during cargo tank cool down. Circulating warm gas through the cargo tanksduring warm-up operations.

LNG1032-135 :

A :

Can you state 3 uses of the HD compressor?





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 fromescaping 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?


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?


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?


If the flow rate falls below the designed minimum preset ratio between gas flow and compressor differential pressure signals, the anti-surge controller produces asignal 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. Thecompressor 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, designedminimum flow rate?


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 orboth compressors.

LNG1032-140 :

A :

What is the problem when two compressors are run in parallel? What is the solution?


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?


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?


To supply boil-off gas to the boilers.

LNG1032-144 :

A :

What are the LD compressors used for?





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?


In the engine control room.

LNG1032-146 :

A :

Where are the remote controllers for the LD compressors situated?


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?


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 HDcompressors for warming up the cargo tanks prior to inerting.

LNG1032-148 :

A :

What is the use of the gas heaters?


+80C

LNG1032-149 :

A :

What is the maximum temperature the heater outlet would be set to for tank warming up operations?


+20C

LNG1032-150 :

A :

What temperature would the heater outlet normally be set to for supplying gas to the boilers?


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?


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?


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?





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 byspray/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?


-30 to -40C

LNG1032-155 :

A :

At what temperature is the gas outlet from the forcing vaporiser usually controlled?


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 LDcompressor.

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?


Low Low condensate temperature, set point 80C. 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?


Two

LNG1032-158 :

A :

How many main cargo pumps are normally fitted in each tank of both Moss and Membrane type vessels?


Partially open.

LNG1032-159 :

A :

What position should the discharge valve of a main cargo pump be in prior to starting the pump?


By altering the position of the discharge valve.

LNG1032-160 :

A :

How is the discharge rate of a cargo pump controlled?


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?


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?





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 stabiliseconditions.

LNG1032-163 :

A :

How do you know that a cargo pump is cavitating? What would be your action in this case?


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?


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?


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 orequal 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?


It must be completely isolated.

LNG1032-167 :

A :

What is the key requirement before any inspection or maintenance is undertaken on electrical equipment?


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?


Insulation resistance testing and recording of the pump cables and motors on all loaded voyages. Recording of pump amps, position of discharge valve, dischargepressure during bulk discharge to establish any trend. Routine inspection/cleaning of starter boxes, all connections to be clean and tight. Routine testing of allassociated 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?


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 theforcing 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?


One in each tank.

LNG1032-171 :

A :

How many stripping/spray pumps are normally fitted in an LNG carrier?





Single stage pump fitted with an inducer, driven by submerged electric motor

LNG1032-172 :

A :

What type of pump is the stripping/spray pump?


10% open

LNG1032-173 :

A :

What state should the discharge valve be in prior to starting a stripping/spray pump?


After the first main pump in the tank has been stopped and the liquid level is above the height of the stripping pump.

LNG1032-174 :

A :

When are stripping/spray pumps normally started if the tanks are going to be "heeled out" (i.e. the maximum amount of cargo is to bedischarged ashore)?


The pump must never be run dry because the flow of LNG through it cools the motor windings and cools and lubricates the motor bearings.

LNG1032-175 :

A :

What happens if a main cargo pump runs dry?


On starting, when the discharge pressure is seen to increase and the motor amps are seen to decrease, this indicates that the pump is operating satisfactorily andflow has been established.

LNG1032-176 :

A :

On starting, how do you know that the pump is operating satisfactorily and flow has been established?


No.

LNG1032-177 :

A :

Can stripping/spray pumps be started normally at any tank level?


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. Controlair pressure Low Low.

LNG1032-178 :

A :

Can you state 3 situations that will trip the stripping/spray pumps?


A soft starter is a reduced voltage starter for AC induction motors replacing mechanical contacts with solid state devices (thyristors) to control the current flow andtherefore the voltage applied to the motor. The most common thyristors are known as silicon controlled rectifiers (SCRs) and triacs.

LNG1032-179 :

A :

What is a AC induction motor soft starter?


Soft starters designed to control only one phase will reduce the torque but not the motor current on two phases. Soft starters designed to control two phases willreduce the torque but the current will not be optimally reduced or balanced. Soft starters designed to control three phases will reduce the current and the torque.

LNG1032-180 :

A :

A soft starter controls the current flow and therefore the voltage applied to the motor. What is happening in the motor if a soft starter isapplied to 1, 2 or all the 3 phases of the motor?





Maintenance of cabling connections/junction boxes, pump motors and pumps is normally carried out only at refit.

LNG1032-181 :

A :

When is carried out the maintenance of cabling connections/junction boxes, pump motors and pumps?Wrong or Missed Data? Click

When a pump is opened up for inspection the motor bearings are always renewed irrespective of their condition.

LNG1032-182 :

A :

In which cases are you changing the bearings of a pump when it is opened up for inspection?


A regular record is kept of pump and cable insulation resistance to earth, usually taken once every round voyage.

LNG1032-183 :

A :

What kind of record will keep the electrican about the cargo pumps?


Pilot operated relief valves.

LNG1032-184 :

A :

What types of device are normally fitted to the cargo tanks to act as safety relief valves to protect the tank from over pressurisation?


Two

LNG1032-185 :

A :

How many relief valves are normally fitted to each cargo tank?


Pressure relief valves should be connected to the highest part of the cargo tank above deck level.

LNG1032-186 :

A :

Where should the cargo tank pressure relief valves be installed?


Relief valves should be connected to a venting system which is constructed so that the discharge of gas will be directed upwards and arranged so as to minimise thepossibility of water or snow entering the vent system.

LNG1032-187 :

A :

What are the construction requirements of the venting system of the cargo tank pressure relief valves?


Cargo tank relief valves are usually overhauled, set and sealed during refit under the supervision of the classification society.

LNG1032-188 :

A :

When are cargo tank relief valves usually overhauled, set and sealed? Under which supervision?


20% of the MARVS

LNG1032-189 :

A :

The cargo tank relief valves should have a combined relieving capacity such as to prevent the tank pressure from rising more thanwhich value?





So that no water can collect on the top of the valve piston, causing added back pressure and so changing the lifting pressure of the valve.

LNG1032-190 :

A :

Why is it important that all drains on the relief valve vent line are kept clear so that any water/condensation that does get into the ventcan be drained away?


Because a relief valve must be fitted to every section of liquid cargo line that can be isolated by two valves.

LNG1032-191 :

A :

Why are so many cargo line relief valves fitted to the liquid cargo lines on an LNG vessel?


Back to a cargo tank

LNG1032-192 :

A :

Where do the cargo liquid line relief valves discharge to?


The cargo line relief valves must be tested every 5 years for classification survey.

LNG1032-193 :

A :

When must the cargo line relief valves be tested?


Because these valves are rarely activated it is possible for the valve disks to stick in their seats or, if they are activated, they may not re-seat tightly again.

LNG1032-194 :

A :

What is an important consideration when testing the tank safety relief valves?


The outlet line from the valve will be frosted up.

LNG1032-195 :

A :

How do you know if a cargo line safety valve has lifted or if it is leaking?


Yes

LNG1032-196 :

A :

Can cargo line relief valves be fitted with manual test levers?


-120C

LNG1032-197 :

A :

In a membrane vessel, at what temperature are the alarm points set on the thermocouple sensors in the secondary insulation barrier?


0C

LNG1032-198 :

A :

In a membrane vessel, at what temperature are the alarm points set on the thermocouple sensors in the inner hull?





To prevent flammable mixtures forming in the event of a LNG leak in the tank. To permit easy detection of an LNG leak through the barrier. To prevent anycorrosion taking place.

LNG1032-199 :

A :

In both Moss and membrane vessels, why is nitrogen supplied to the insulation space(s)?Wrong or Missed Data? Click

0.2 - 0.4 kPa

LNG1032-200 :

A :

In a membrane vessel, at what pressure should the primary and secondary insulation spaces be kept under normal conditions?


RTD's (Resistance Temperature Detectors) do not require special cables to connect the sensor, unlike thermocouples.

LNG1032-201 :

A :

What is the advantage of RTD's (Resistance Temperature Detectors) vs thermocouples?Wrong or Missed Data? Click

RTD cables cannot be run alongside other electric cables and close to motors and switchgear without being affected.

LNG1032-202 :

A :

What can affect the correct reading of RTD's (Resistance Temperature Detectors)?Wrong or Missed Data? Click

In a capacitive pressure transducer, the pressure sensing element is a pair of parallel plates which form a capacitor. The capacitance varies with changes inpressure, which in turn are converted to a voltage that is linearly proportional to the pressure.

LNG1032-203 :

A :

What is the pressure sensing element in a capacitive pressure transducer?


O-rings and seals that are used have a limited lifespan and can deteriorate. Dust and vapour condensation can accumulate possibly forming scale on the valvepiston and stem causing them to stick in the guides. Water building up because of blocked drain lines can accumulate on top of the piston causing added backpressure.

LNG1032-204 :

A :

What are the main problems that might be encountered with cargo space relief valves due to their exposed position on deck and theirinfrequent activation?


Valves used can be Gate, Globe, Check, Ball and Butterfly valves.

LNG1032-205 :

A :

Which type of valves can be used?


Butterfly and Globe valves are the best valves to use when throttling control is required.

LNG1032-206 :

A :

What is/are the best type(s) of valves to use when throttling control is required?Wrong or Missed Data? Click

Gate valves and Ball valves give least resistance to flow when in the full open position and make excellent shut off valves.

LNG1032-207 :

A :

When are the Gate valves and Ball valves the best choice?





Rotary motion valves such as ball and butterfly valves rotate a quarter-turn or more from open to closed. Linear motion valves such as gate and globe valves have asliding stem design that pushes the closure element open or closed.

LNG1032-208 :

A :

What is the main difference between ball/butterfly valves and gate/globe valves?


Voltage Milliampere Pressure

LNG1032-209 :

A :

What are the basic types of control signal input for a valve actuator?


The end connections with the piping. The spindle gland seals. The sealed top closure joint on top entry valves. Any valve drain or vent connections.

LNG1032-210 :

A :

An important requirement in LNG valve design is to minimise leakage into the surrounding environment. Which leakage points should bekept under close scrutiny during cargo operations?


In the event of an emergency, all actuators fitted to cargo liquid and vapour valves must be fitted with a means of manual emergency operation.

LNG1032-211 :

A :

What is the requirement for all actuators fitted to cargo liquid and vapour valves in the event of an emergency?


If a handwheel or lever type override is to be used, the hydraulic or pneumatic side of the valve must be overridden before engaging it and attempting to operate thevalve.

LNG1032-212 :

A :

All actuators fitted to cargo liquid and vapour valves must be fitted with a means of manual emergency operation. What do you need todo to the hydraulic or pneumatic side before using the handwheel or lever?


Check that the sump tank on the emergency hand pump is at the correct level. On the actuator cylinder to be operated, isolate the hydraulic supply and return valves.Fit the flexible hose snap-on connectors. Shut the hand pump unloading valve. Operate the direction control valve lever to give the desire movement of the cylinder.Operate the hand pump until the valve has reached its desired position.

LNG1032-213 :

A :

Which set sequence is involved when connecting and operating an emergency hydraulic power pack?


Very high level - over filling protection Very low pressure protection High pressure protection

LNG1032-214 :

A :

Can you indicate 3 protection systems fitted to the cargo tank?


An increase in gas readings for that tank by the gas detection system.

LNG1032-215 :

A :

What would be the first indication if the primary barrier developed a small leak?


The Very High Level alarm that gives an ESD and shuts everything down must be independent from all other alarm and trip systems.

LNG1032-216 :

A :

What does the Very High Level alarm? Can this alarm be combined with the High Level alarm?





While the tank is filling, the level is continuously monitored by the primary Custody Transfer System.

LNG1032-217 :

A :

What is the name of the tank level monitoring equipment?


If the tank pressure gets too low, the ESD is activated and shuts everything down before the pressure falls below atmospheric.

LNG1032-218 :

A :

What happens if the tank pressure gets too low?


Modern analysers normally only require a field zero calibration which requires 99.9 pure nitrogen. The units can be field spanned by using a certified calibratedmixture of methane in nitrogen. On modern units, field span calibrations can be done by connecting a computer and using the manufacturer's software package.

LNG1032-219 :

A :

How do you calibrate a modern infra-red gas analyser?


The analyser works by comparing the infra red spectrum of methane against a reference sample of air.

LNG1032-220 :

A :

How does work an infra-red gas analyser?


It does not have any electric cabling or moving mechanical parts inside the tank, so repairs/maintenance can be carried out easily in service.

LNG1032-221 :

A :

What is the main advantage of the radar type level gauging system over other methods such as Transonic or float systems?


At the first loading after refit.

LNG1032-222 :

A :

When are the High High and Overfill alarms normally tested by actual liquid loading?


Brayton cycle (reversed constant pressure cycle) nitrogen system.

LNG1032-223 :

A :

Which re-liquefaction system is considered to be the most practical for use on board LNG vessels?


The LNG re-liquefaction plant is basically a cascade system utilising the energy from the expansion of high pressure nitrogen in a high speed turbine to drive the finalstage in the form of a turbo expander. The nitrogen from the turbo expander circulates through a cargo condenser, removing the heat from the circulating LNGvapour. The LNG vapour returns to the cargo tanks as a liquid.

LNG1032-224 :

A :

Describe the operating principles of a re-liquefaction plant that could be installed on board of a vessel.


The Gas Combustion Unit provides an environmentally-friendly solution for excess boil-off gas combustion on LNG carriers. It cannot be used while discharging.

LNG1032-225 :

A :

What is a Gas Combustion Unit? Can you use it while discharging?





535C

LNG1032-226 :

A :

What is the maximum allowable flue gas temperature of a Gas Combustion Unit?


To discharge cargo ashore as a gas.

LNG1032-227 :

A :

What is a re-gasification plant used for?


They are all enclosed spaces, so full tank entry safety procedures must be carried out and permits issued prior to entering.

LNG1032-228 :

A :

What do hold spaces, ballast tanks, cofferdams and duct keels have in common?


There is always a lot of condensation/water from the ice formed on the pipes and compressors so it is never dry once the vessel is cooled down.

LNG1032-229 :

A :

Why is it very difficult to perform cosmetic maintenance in the compressor room when the vessel is in service?


Infrared type meter

LNG1032-230 :

A :

What type of portable test instrument must be used to measure the methane content in nitrogen or inert gas?


Each space to be inspected once every 6 months.

LNG1032-231 :

A :

What is the normal frequency of inspection/cold spotting for all spaces surrounding the cargo tanks? i.e. Ballast tanks, cofferdamswhaleback spaces, hold spaces and duct keels?


30-169mm

LNG1032-91 :

A :

What is the wall thickness of the aluminium spherical tanks in a Moss type vessel?


IGC max. filling limit is 98% volume of the tank. Higher filling limits are permitted with Flag State and Class approval. Moss type vessels CANNOT normally load to alevel of 99.8% of tank volume.

LNG1032-92 :

A :

What is the maximum filling limit according to the IGC code? Are higher filling limits possible? Can Moss type vessels normally load toa level of 99.8% of tank volume?


0.0015

LNG1032-93 :

A :

What is the normal guaranteed boil-off rate per day in a modern Moss type vessel?





By a skirt welded to the equatorial ring of the tank and to the hull structure.

LNG1032-94 :

A :

How are the spherical tanks supported in the hull structure of the vessel?


So that the space between the insulation and tank can be continuously purged with nitrogen.

LNG1032-95 :

A :

Why is the insulation not bonded to the tank surface in a Moss type vessel?


So that the outlet flow of nitrogen from the space can be monitored for any possible gas leakage from the tank. To keep the space dry to prevent any possiblecorrosion of the tank. To keep the space dry so no ice can form from moist air or CO2. To keep an inert atmosphere around the tank.

LNG1032-96 :

A :

Why is the annular space purged continuously with nitrogen?


0.7mm

LNG1032-97 :

A :

What is the thickness of the Invar primary and secondary membranes of the Gas Transport NO 96 System?


250mm

LNG1032-98 :

A :

What is the approximate thickness of the insulation in the Technigaz Mark III system to allow a boil-off rate of 0.15% per day?


530mm

LNG1032-99 :

A :

What is the approximate thickness of the insulation in the Gas Transport NO 96 System to allow a boil-off rate of 0.15% per day?




3.Support Systems (Module 3) - test for Cargo Engineer

To prevent the formation of flammable mixtures in the event of any LNG leakage. To permit easy detection of any LNG leakage through the barrier(s). To preventcorrosion in the insulation space.

LNG1032-232 :

A :

What are the reasons for supplying nitrogen as a dry inert gas to the insulation spaces on LNG carriers?


0.2kPa to 0.4kPa

LNG1032-233 :

A :

What is the normal controlled pressure in the primary barrier space of a membrane vessel?


GTT NO96 system

LNG1032-234 :

A :

Which containment system has a pressure control system for the insulation spaces that is common to all tanks?


The Hold Space.

LNG1032-235 :

A :

Where does the nitrogen supplied to the annular space exhaust to on a Moss vessel under normal stable conditions?


No. An LNG leak through the barrier needs to be detected.

LNG1032-236 :

A :

Is it allowed to have the primary space above tank pressure?


5C

LNG1032-237 :

A :

At what temperature should the cofferdam heating maintain the cofferdams during the loaded passage?


The void space around the liquid domes.

LNG1032-238 :

A :

Apart from the cofferdam, what other space is usually heated by the cofferdam heating?


Cargo pump discharge lines. HD and LD compressor discharge lines. Inert gas supply line.

LNG1032-239 :

A :

Can you give 3 examples of non-return valves fitted on the vessel lines?


So that trapped vapour in the spindle insulates the operating mechanism and stops it from freezing.

LNG1032-240 :

A :

Why are most cryogenic valves fitted with extended spindles?





Expansion/contraction must be allowed for in the form of either bellows or loops in the pipe line. Only a couple of supports on the line are fixed, the rest allow thepipeline to move horizontally. Where bellows are fitted in pipelines they are not lagged but must be kept covered with an air tight shroud to prevent freezing and icebuild up on them.

LNG1032-241 :

A :

What is specific about the construction of LNG pipelines?


Secondary barrier. Cofferdam. On inner hull in duct keel. On inner hull in trunk deck.

LNG1032-242 :

A :

Where are temperature indicating devices installed on a membrane vessel?


It is better to suspend operations in a controlled manner and rectify the problem rather than allow trips or shut-downs to occur. A record of alarms and subsequentactions should be maintained.

LNG1032-243 :

A :

In the event of an alarm, if the situation cannot be rectified, is it OK to continue operations until the associated trip operates?


The lowest concentration of the gas in air that will support a self-propagating flame when ignited.

LNG1032-244 :

A :

What is the lower flammable limit (LFL) of a combustible gas?Wrong or Missed Data? Click

Electric motor rooms. Ventilation hoods and gas ducts (swept trunking for gas to boilers). Air locks, such as to accommodation and CCR entrances. [3 examplesonly] There is no gas detection head in the cargo tank insulation spaces.

LNG1032-245 :

A :

Can you give 3 places that would be fitted with a constant sampling catalytic gas detection head? Can you find such a gas detectionhead in the cargo tank insulation spaces?


Catalytic gas detectors require the gas sample to be mixed with air or oxygen in order to operate. Infra-red gas analysers do not require the gas sample to be mixedwith air or oxygen in order to operate.

LNG1032-246 :

A :

What is the difference between catalytic gas detectors and infra-red gas analysers in relation to the gas sample?


30% LFL

LNG1032-247 :

A :

At what gas concentration should the alarm point be set for the gas detection units on board an LNG vessel?


Detectors should be subject to regular calibration every 3 months to ensure that the zero and span of the instrument is correct.

LNG1032-248 :

A :

What are the requirements for testing of the gas detectors?


Detectors should be subject to regular calibration every 3 months to ensure that the zero and span of the instrument is correct. On cyclic sampling systems, suctionline integrity and filters should also be checked at regular intervals.

LNG1032-249 :

A :

What are the requirements for testing of cyclic sampling gas detection systems?





At least 2 sets

LNG1032-250 :

A :

How many sets of portable gas detection equipment, suitable for detecting vapour up to the LFL of gas on board, must an LNG vesselcarry?


Top, mid height and bottom of the tank.

LNG1032-251 :

A :

When testing a confined space for gas prior to entry, where should the sample be taken from?


Infra-red type instrument

LNG1032-252 :

A :

What type of meter is used to measure hydrocarbon concentration in an inert atmosphere?


Sample A.

LNG1032-253 :

A :

Which sample of air, having the dew point readings given, would contain the most moisture? Sample A with a dew point of-20C or Sample B with a dew point of -45C?


Meters with infra-red sensors

LNG1032-254 :

A :

Which of the meter types can not be used to measure oxygen levels?


Catalytic meters are using a sensor filament that varies in resistance when the gas combined with the oxygen burns inside the filament chamber. Catalytic meters arefitted with flashback arrestors in the inlet and outlet of the detector filament chamber to prevent the possibility of flame propagation from the chamber to a hazardousarea.

LNG1032-255 :

A :

Why do catalytic meters require the presence of oxygen in the sample in order to measure the gas concentration? What needs to befitted to the meter inlet and outlet as a consequence of this principle of operation?


The material of the sample hose used must be of the correct type as some rubber hoses can absorb gas and give false readings.

LNG1032-256 :

A :

Is the material of the sample hose of a gas meter important? And why?


Yes.

LNG1032-257 :

A :

Can a meter using infra-red sensors be made specific to a particular gas?


During the final stages of gassing up the cargo tanks.

LNG1032-258 :

A :

During which operation would CO2 readings be taken to check the amount of CO2 present?





Evacuate the space immediately.

LNG1032-259 :

A :

If, while work is in progress in a confined space, either the O2 reading is seen to decrease or the gas content increase during a periodiccheck, what should be the first course of action?


Main cargo and stripping pumps. HD compressor. Manifold valves. Cargo loading and discharge valves.

LNG1032-260 :

A :

In the event of an Emergency Shut Down (ESD) on an LNG vessel carrying out cargo operations in port, can you state 4 items that willbe shut down?


An ESD 1 can be activated by either ship or shore. An ESD 2 is actived by the shore. An ESD 2 activates everything an ESD 1 does plus it closes valves in theloading arms and disconnects them from the vessel.

LNG1032-261 :

A :

Who activates an ESD 1? And an ESD 2? What does an ESD 2 in addition to ESD 1?


No longer than 30 seconds.

LNG1032-262 :

A :

What is the time required by the International Gas Code for closing the manifold valves?


Very High cargo tank level 99%. Cargo tank pressure falls to within 0.5kPa of primary space pressure. Vapour line pressure falls within 0.3kPa of atmosphericpressure. Loss of control air pressure. Loss of cargo valve hydraulic oil pressure.

LNG1032-263 :

A :

Can you give 5 causes of ESD?


Trip ship's cargo and spray pumps (if discharge port). Trip HD compressors (if loading port). Close ship's Manifold/ESD valves.

LNG1032-264 :

A :

In the event of a shore side ESD being activated, what will occur on board the vessel?


Prior to arrival at each loading/discharge port.

LNG1032-265 :

A :

How often should the ESD system trips and alarm be tested?


Yes

LNG1032-266 :

A :

May the terminal have specific requirements for testing the ESD?


The quick release hooks can be activated and the vessel moved from the berth by tugs using the fire wires without the assistance of crew.

LNG1032-267 :

A :

What is the purpose of the quick release hooks?





Fire wires are rigged forward and aft to hang over the outboard side (opposite side to the berth) of the vessel on arrival at each port.

LNG1032-268 :

A :

Where are rigged the fire wires?


During all cargo transfer operations

LNG1032-269 :

A :

When should water curtains which spray water down the ship's side under the manifolds be operated?


The drench system must protect the accommodation, CCR, compressor room, valves and equipment etc. from heat and spread of fire in the event of a fire/explosionin the cargo area.

LNG1032-270 :

A :

What is the role of the water drenching system (spray system)?Wrong or Missed Data? Click

The pump(s) must be able to be started remotely from outside the cargo area.

LNG1032-271 :

A :

Where can you operate the pump(s) of the water drenching system (spray system)?Wrong or Missed Data? Click

At least two hand held hoses or combination hoses/monitors are required to cover any part of the cargo deck including all above deck piping.

LNG1032-272 :

A :

What is the required capability of a fixed dry powder type extinguishing system on board an LNG vessel?


Compressed nitrogen.

LNG1032-273 :

A :

What medium is used as the propellant in fixed dry powder extinguishing systems to discharge the powder?


Monitors should be fitted to protect the manifold areas and be capable of actuation both locally or remotely.

LNG1032-274 :

A :

Where are monitors fitted? Where could they be activated?


10kg/sec

LNG1032-275 :

A :

What should be the minimum discharge capacity of a fixed dry powder monitor?


3.5kg/sec

LNG1032-276 :

A :

What should be the minimum discharge capacity of a fixed dry powder hand held hose nozzle?





35 metres

LNG1032-277 :

A :

What should be the maximum length of a fixed dry powder hand held hose line?


45 seconds

LNG1032-278 :

A :

A sufficient quantity of dry chemical powder should be stored in each unit to ensure that all monitors and hand held hoses will dischargefor which minimum time?


Float type. Radar type. Capacitance type.

LNG1032-279 :

A :

Can you give 3 cargo tank gauging devices that can be used on board an LNG vessel?


There must be an independent alarm and ESD trip for very high level completely independent from the gauging system.

LNG1032-280 :

A :

Can the tank gauging system be combined with the high alarm that will close that particular tank's filling valve? Can the tank gaugingsystem be combined with the high high alarm that will cause an ESD?


To ensure that the float maintains the same level of immersion irrespective of the amount and weight of the tape paid out.

LNG1032-281 :

A :

In a float level gauge why is a constant torque spring incorporated into the tape winding pulley?


Never. Floats should always be left in the stowed position after taking a reading and never left in the "down" position, even when loading or discharging as well aswhen at sea.

LNG1032-282 :

A :

When can the float level gauges be left in the "down" position?


The capacitance segments and cables are all inside the tank.

LNG1032-283 :

A :

What is the biggest disadvantage of a capacitance type level gauging system?


There are no moving parts or electrical connections inside the tank.

LNG1032-284 :

A :

What is the biggest advantage of a radar type level gauging system?


It is the accurate measurement of the volume, temperature and pressure of the cargo loaded or discharged.

LNG1032-285 :

A :

What is meant by Custody Transfer System (CTS)?Wrong or Missed Data? Click




Volume Temperature Pressure The density is determined ashore.

LNG1032-286 :

A :

What is supplied by the vessel for calculating the calorific content of the LNG discharged?


The radar transmitter located on the top of the tank emits microwaves, directed by an antenna, towards the surface of the tank contents. The antenna picks up theecho from the surface. The difference in frequency between the transmitted and reflected signal is directly proportional to the measured distance which is the ullage.

LNG1032-287 :

A :

What is the basic principle of a radar type level gauging system?


Before loading After loading Before discharging After discharging

LNG1032-288 :

A :

At what stage(s) in cargo operations are CTS reports (LNG Certificates) printed out manually and also filed electronically?Wrong or Missed Data? Click

The Float System.

LNG1032-289 :

A :

Which gauging system is independent of all other systems and external sources (e.g. electrical)?Wrong or Missed Data? Click

The Radar System.

LNG1032-290 :

A :

Which gauging system has no electrical cabling or moving parts inside the tank?


The Capacitance System.

LNG1032-291 :

A :

Which gauging system cannot be removed and overhauled with the tank still in service?


No.

LNG1032-292 :

A :

Is an area 3 metres aft of the cargo area and 3 metres above the weather deck classed as being in the gas dangerous zone on anLNG carrier as defined by the IGC?


The control panel, monitor screen and alphanumeric keyboard.

LNG1032-309 :

A :

What is the IAS system (Integrated Automation System) operator interface?Wrong or Missed Data? Click

Power management. Propulsion plant. Cargo and ballast control. Watch call system.

LNG1032-310 :

A :

What is the role of the AIS (Integrated Automation System)?Wrong or Missed Data? Click




Process and system monitoring Event logging and monitoring Control functions (motor control, valve control, PIDs)

LNG1032-311 :

A :

What are the basic functions carried out by the IAS (Integrated Automation System)?Wrong or Missed Data? Click

The IAS is a distributed processing system because the control functions are defined locally in the process stations and not in the operator stations. In the event offailure of control of any equipment then it is possible to change from IAS control to manual local control.

LNG1032-312 :

A :

Why is AIS (Integrated Automation System) defined as a distributed processing system?Wrong or Missed Data? Click

An impulse turbine has fixed nozzles that change the steam flow into high speed steam jets. These jets contain significant kinetic energy, which the rotor blades,shaped like buckets, convert into shaft rotation as the steam jet changes direction. A pressure drop occurs across only the stationary blades with a net increase insteam velocity across the stage.

LNG1032-315 :

A :

How does operate an impulse turbine?


700-900C

LNG1032-316 :

A :

What temperature does the air reach on the compression stroke in the cylinder of a diesel engine?


Turbo chargers are used to compress the air into the cylinders of a diesel engine so that more fuel can be burnt and so more power can be developed.

LNG1032-317 :

A :

What is the use of turbo chargers on Diesel engines?


In a diesel electric power plant the diesel generators are run at their optimum load for fuel efficiency and are stopped or started depending on the speed required.

LNG1032-318 :

A :

What is the main advantage of a diesel electric power plant?


Gas turbines have a high power-to-weight ratio.

LNG1032-319 :

A :

What is an important advantage of gas turbines?


Main condenser vacuum low. Main condenser sea cooling water outlet high. Main condenser inlet valve not fully open.

LNG1032-320 :

A :

Can you state 3 situations that will trip the main steam dump valve?


535C

LNG1032-321 :

A :

What is the maximum flue gas temperature allowable in a gas combustion unit?





Nitrogen

LNG1032-322 :

A :

In a Brayton cycle (Reversed constant pressure cycle) re-liquefaction system, which gas is used for the refrigerant?Wrong or Missed Data? Click

0.0015

LNG1032-323 :

A :

What is the normal guaranteed, loaded passage boil-off rate of LNG per day in present day vessels?


100% of the boil-off gas normally produced by a full cargo.

LNG1032-324 :

A :

What is the maximum boil-off that the steam plant is designed to handle with the boilers on full load?


Gas detection in swept trunk or canopy hood Very Low gas temperature to boilers Very High gas pressure to boilers Very Low gas pressure to boilers

LNG1032-325 :

A :

Can you give 4 situations that will trip the master gas valve?


1) Get permission from the bridge or CCR to start gas burning. 2) Check safety chain for main gas valve is healthy, that all burner fuel valves are indicating open, andstable FO flame is established in boilers. 3) Open main gas valve. 4) When gas purge of main gas line completed, open boiler gas valves Gp and Gs 5) When gaspurge of boiler lines completed, open individual gas burner valves on each boiler.

LNG1032-326 :

A :

What are the steps to start gas burning in the boilers?


All gas lines are systematically purged with nitrogen so that on completion only nitrogen is left in them.

LNG1032-327 :

A :

When gas burning is stopped, what subsequent operation is carried out automatically?


The gas temperature must not be too low. Engine room ventilation must meet certain conditions, i.e. there must be a specified number of supply and exhaust fansrunning.

LNG1032-328 :

A :

Can you give 2 pre-conditions to allow gas burning?


To atmosphere via a vent line which exits half way up the back of the funnel or to the nearest vent riser mast (most aft one)

LNG1032-329 :

A :

Where is the gas purged to during nitrogen purges after the gas is shut off to the boilers?


- Safety Vent low pressure (by Safety Valve) 20 kPa - Safety Vent high pressure (by Safety Valve) 0.3 kPa - Automatically Vent Valve opens at 2.5 kPa - HighPressure Alarm at 2.8 kPa - Cargo tank pressure low alarm at 2.0 kPa - Tank Protection Activa

LNG1032-330 :

A :

In relation to the vapour header pressure, can you give the pressure values at which the following functions activate: - Safety Vent lowpressure (by Safety Valve) - Safety Vent high pressure (by Safety Valve) - Automatically Vent Valve opens - High Pressure Alarm -Cargo tank pressure low alarm - Tank protection activate, trip gas valve and LD compressor - ESD Activate - FO Back-up Order toBoiler Control System, Cargo tank pressure low low alarm, takes control of LD compressor





A low selector that provides the lower signal from the boiler fuel gas valve position and the cargo tank pressure.

LNG1032-331 :

Documents

Videotel Cbt Lng 1032 Q&A v100