What is Inert Gas or IG and its composition , source of generation and types in detail ?

Written by Amit Sharma

Inert gas means a gas or a mixture of gases, such as flue gas, containing insufficient oxygen to support the combustion of hydrocarbons.

The oxygen content of the Inert Gas  supplied to cargo tanks should be 5% or less. However, it is to be noted that too less content of oxygen in the IG would introduce other impurities into the cargo tanks.

After efficient scrubbing of the inert gas, the typical constituents of a flue gas are :

  • Nitrogen (N)- 83%
  • Carbon Dioxide (CO2)- 12-14%
  • Oxygen( O2) 2-4%
  • Sulphur Dioxide (SO2) 50 ppm
  • Carbon Monoxide (CO) Trace
  • Nitrogen Oxides ( NOx ) 300 ppm
  • Water Vapour (H2O) Trace (hIGh, if not effectively dried)
  • Ash and Soot C Traces
  • Density 1.044 (heavier than air)

Inert condition means a condition in which the oxygen content throughout the atmosphere of a tank has been reduced to 8% or less by volume by addition of inert gas .

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.


  • IG density 1.044t/M3 and Air density at atm pr : 1.22 t/M3 ..how is then iG heavier then air sir..can you confirm or correct me pls

  • Density of IG is mentioned as 1.044 t/m3 , however the density of air is around 1.22 t/m3 at atm pressure,how is then that IG is heavier then air sir..can you clarify or correct me pls

Leave a Comment