An inert gas is one that that does not react with other elements. On a periodic table of elements they are noble gasses which have full valence electron shells which means that they will not react. This non-reactive nature is why they act inert.
They are used when chemical reactions are not wanted, which helps when for example, the user does not want degradation. Inert gasses are specifically used on crude oil carriers. On oil carriers they use flue gas systems or have a dedicated inert gas generator.
The inert gasses are used to make sure cargo does not explode. Also the inert gas can be used to clear the tank of a volatile atmosphere to replace the atmosphere with breathable air. The flue gas system utilizes a boiler exhaust as a source to help create inert gas. The main components for these systems are an exhaust gas source (inert gas is taken from it), isolating value (to server as a supply valve), a scrubbing tower (cleans the gas of soot), gas blower (turbine which drives the gas), regulating valve (controls variation and overheating of the blower fan), deck seal (stop the gas to return from where it came from), sometimes there is a mechanical non-return valve in addition to the deck seal, deck isolating valve (fully isolates the engine room), pressure vacuum, (helps control the pressurization of cargo tanks), cargo isolating valves (controls the flow of inert gas to make sure that the flow is proper), and mast riser (maintains a positive pressure value of inert gas to avoid pressurization of the cargo tank). As you can see there are many precautions to make sure that the system is functioning properly.
Here are some types of ships that require an IG system onboard:
- Product tanker
- Pure chemical tanker
- Petroleum product barges
- Reefers, Crude oil tankers
- Chemical product tankers
These ships all require an inert gas system to prevent explosion in cargo spaces (nitrogen solutions or other combustible solutions need IG systems).