Inert Gas System (IGS)

An inert gas system (IGS) reduces the oxygen content in cargo tank atmospheres below the level supporting combustion, preventing flammable conditions during cargo operations on tankers. SOLAS II-2/4.5.5 and II-2/16.3.3 require an IGS, and resolution MSC.365(93) extended the requirement to oil and chemical tankers of 8,000 dwt and above built on or after 1 January 2016 carrying low-flashpoint cargoes, lowering the previous 20,000 dwt threshold. The system must keep tank oxygen at or below 8 percent by volume and the tanks at positive pressure. Performance follows the FSS Code chapter 15. Crude-oil tankers also use it during crude-oil washing.