Inert gas system
IGS
Meaning
An inert gas system (IGS) fills a tanker's cargo tanks with low-oxygen gas so the hydrocarbon vapours above the cargo cannot ignite.
Also written as Inert gas
Inert gas system explained
Tankers keep cargo tank atmospheres below about 8% oxygen using inert gas, produced from boiler flue gas or a dedicated generator. It is required by SOLAS on most tankers and must be working during crude oil washing.
An IGS failure can stop cargo operations, so delays caused by it are normally for the owner's account.
Related terms
Crude oil washing
Crude oil washing (COW) cleans a crude tanker's cargo tanks during discharge by spraying them with the cargo itself to dislodge residues.
Pumping warranty
A pumping warranty is the owner's promise that the ship can discharge its full cargo within a set time or maintain a set pressure at the manifold.