The Inert Gas System is arguably the most essential safety system on board every product, oil, LNG and crude tanker and many chemical-carrying vessels. It is paramount for creating and sustaining a low-oxygen atmosphere (<5%) within a vessel’s tank to reduce the likelihood of combustions or catastrophic explosions. Inert gases are gases in which combustion cannot occur due to their low levels of oxygen. Although there are different types of Inert Gas Systems, all of them ultimately accomplish the same goal – produce clean inert gases to be fed to vessels’ cargo tanks.
MOSS IGG SYSTEMS (Left: For Product/ Chemical Tankers; Right: For LPG/ LNG)
How it works: IGGs consist of two main units – the burner and the scrubber. Gas of oxygen content between 2-4% is specifically produced by a dedicated burner that burns fuels in normal atmospheric air. IGGs generate their own supply of inert gas, hence the name.
This exhaust gas contains high levels of soot and sulfur dioxide that are harmful to personnel and cause accelerated corrosion. This gas needs to be treated before being used as inert gas. To do so, the gas is pumped through a scrubbing tower where it is cleaned and cooled using seawater before being distributed to cargo tanks.
How it compares: IGGs are more complex in operation than competing types of Inert Gas Systems. They contain many different components and moving parts that must all work in harmony to function, such as the scrubber pump, fuel oil pump, blowers and ignition burners to name a few. Operators should adhere strictly to each of these components’ maintenance schedule to ensure trouble-free operation. For instance, if the control air system, which is prone to breakdowns, is not serviced regularly, the whole operation of the system will be affected as oil and water will be present in the control air. This will have an adverse effect on the system’s efficacy and longevity.
Where it is used: IGGs are suitable for use in small vessels as they are often equipped with smaller boilers that do not produce sufficient flow of exhaust gas to be used as inert gas, hence a dedicated burner is necessary as a source of inert gas.
They are not recommended for medium to large vessels as IGGs take up more space and have higher operating costs due to its dedicated burner as compared to the other two systems. These vessels are usually equipped with larger boilers that provide a sufficient flow of exhaust gas, removing the need for a dedicated burner.
About the writer: Jia Lim is a Service Engineer from GIANTECH Engineering Pte Ltd. Specialising in Inert Gas Systems, he has spent 8 years in the industry servicing different types of IGS by a range of different makers. Jia continues to grow his expertise in IGS, attending service jobs for GIANTECH around the globe regularly.
About GIANTECH: Established since 2001, GIANTECH is a Singapore-based marine engineering company with global operations in countries such as Croatia. The company specialises in the spare part sales and after-sales services for equipment such as inert gas systems, nitrogen generator systems, burners, boilers and P/V valves.
Visit www.igiantech.com for more information.