What is the purpose of filling the free area of a cargo tank with inert gas?
To remove the flammable atmosphere from the tank
When entering any part of the inert gas system to carry out maintenance or inspections, what is the main danger to life?
Oxygen deficiency
What is inert gas?
As It is a gas containing insufficient oxygen to support the combustion of hydrocarbons
The regulations say that safely inerted gas mixtures should contain:
Less than 8 % oxygen
Which of these points (start up procedure) should be executed first?
Open the flue gas-isolating valve
When working in parts of the inert gas system such as the scrubber or deck water seal, what procedures must be followed?
Enclosed space entry
What is the purpose of introducing inert gas into a cargo tank?
To create a non-explosive atmosphere in the tank
hat is the meaning of the expression “gas freeing”?
To introduce fresh air into a tank
What is the meaning of the expression “purging”?
To blow inert gas through the tank to reduce the oxygen or hydrocarbon gas level in an already inerted tank
What happens in the flue gas system if the pressure in the cargo tanks and Inert Gas Main becomes less than 50 mm Water Gauge during cargo discharge operations?
Cargo pumps shutdown automatically
Which of these points (start up procedure) should be executed first?
Open the flue gas-isolating valve
What is the maximum oxygen content of the inert gas delivered to the tanks?
5% by volume
How much time can it take before the oxygen analyser reading is accurate?
Up to two hours
What are consequences of a ‘high-high’ oxygen content alarm sound during normal operation? This is when the oxygen content of the inert gas becomes more than 8 percent?
The pressure control valve will automatically close, and the vent-to-atmosphere valve will open
During air venting/gas freeing of tanks the blowers draw air in from were?
The blower fresh air inlet
Which of these points shall be executed last in the shutdown procedure?
Shut down inert gas blower
Are all pumps and blowers shut down during the shutdown procedure?
No, the seawater pumps are left running
How often must the scrubber be flushed with water?
Every time it is used
How often must the non-return valve be opened for internal inspection?
Once a year/18 months
In a mixture of hydrocarbon gas and air, what does ‘Upper flammable limit’ UFL, mean?
It is the point where the concentration of hydrocarbon vapour becomes too high to support combustion
In a mixture of hydrocarbon gas and air, what does ‘Lower flammable limit’ LFL, mean?
It is the point where the concentration of hydrocarbon vapour becomes too low to support combustion
What is the purpose of the deck water seal?
To prevent backflow of gas into the engine room
What is the purpose of the pressure/vacuum breaker?
To relieve excess pressure or vacuum in the inert gas system
Why is sealing air supplied to the boiler uptake valves?
To prevent deposits and flue gas leakage in the uptake system when the plant is shut down
When the scrubber water flow rate drops below the design rate an alarm is given. What will happen if the flow rate drops further?
The inert gas blowers will stop
If the inert gas temperature at the blower outlet reaches 65 degrees celsius, a high temperature alarm is given. What will happen if the high, high temperature alarm is triggered?
The inert gas blowers will stop which result in the inert gas system stopping
Which of following pieces of equipment prevents excessive overpressure or vacuum in the inert gas system?
P/V Breaker
What are the causes of high oxygen content indication on the oxygen analyser? Please click all answers that apply.
Poor combustion control of the boile
Incorrect calibration of the oxygen analyser
Drawing air down the boiler uptake during low load operation
How long must the deck water seal supply be left on?
Must be left running to maintain an adequate seal
The above diagrams represent different types of deck seal. Which one is the wet type deck seal?
A