Inerting – also known as blanketing – is the process of using inert gas to displace and eliminate oxygen or moisture during industrial storage, processing, or transport. Inerting is crucial in many industries to prevent ignition or explosion of flammable substances and to protect equipment, materials, or products from corrosion.
Basic Principles of Inerting
Oxidation is commonly considered to be a chemical change caused by the addition of oxygen. While this isn’t technically accurate, it is true that oxygen is most commonly the cause of oxidation, as many substances readily react with it causing them to degrade or undergo unwanted chemical changes. When oxidation gives off enough energy or happens rapidly enough we call it combustion or, in extreme cases, explosion. Through oxidation, oxygen in many industrial environments, can pose a serious problem.
Moisture – the presence of water vapour in the air – is another not-so-obvious threat. We tolerate various levels of humidity in our daily lives. In industry, however, moisture is an insidious contaminant with the ability to dramatically reduce product quality, damage equipment, and increase costs.
Inerting is the process of replacing air in an enclosed space (which contains high levels of oxygen and moisture) with a non-reactive (inert) gas. Doing so prevents oxygen and/or moisture from coming into contact with reactive products or materials.
Safety Benefits of Inerting
In many applications, inerting is a safety-critical measure when storing flammable materials. Inerting is usually considered in cases where it is impractical to eliminate ignition sources and/or ensure substances are below flammable limits.2,3 Typical use cases include storage tanks where flammable materials are stored above their flashpoints and reactor systems where excursions into flammable atmospheres occur. Inerting gases may also be used to prevent dust explosions in chemical processing industries or to protect equipment from corrosion.
The importance of inerting can clearly be seen when looking at the history of oil tankers.4 Prior to the 1980s, there were very limited requirements for tankers with flammable cargo to use inerting systems. As a consequence, tanker explosions were not uncommon, often due to the accidental introduction of ignition sources during the refueling or loading process. Following the introduction of a surcharge on very large crude carriers, many were fitted with inerting gas systems, significantly reducing the number of explosions and reminding us of the importance of inerting, even in situations where ignition sources may not be readily apparent.
Quality Benefits of Inerting
Inerting also plays a fundamental role in ensuring product quality in many industries. In the semiconductor industry, for example, moisture and oxygen can both have a detrimental effect during manufacturing; and inerting gases such as nitrogen are typically used throughout the production process.5 In the food and drink industry, inerting gases play a crucial role in protecting products from spoilage. For example, edible oils are typically blanketed in nitrogen during tank storage.6
Inerting Gas Solutions from Air Products
Due to its negligible environmental impact, nitrogen is the most commonly used inerting gas.7 Other gases such as carbon dioxide, argon, and helium are used in other applications. Air Products can advise on the optimum gas for your application while keeping gas usage to a minimum. Visit our website or get in touch for more information about our inerting/blanketing gas services.
References and Further Reading
- Hazardous Substance Fact Sheet | Oxygen | NJDHSS. https://nj.gov/health/eoh/rtkweb/documents/fs/1448.pdf.
- Inerting in the Chemical Industry. https://www.boconline.co.uk/en/images/Inerting-in-the-chemical-industry_tcm410-166975.pdf.
- Inerting. https://www.hse.gov.uk/comah/sragtech/techmeasinerting.htm.
- Devanney, J. The Strange History of Tank Inerting. 19.
- Takano, S. Semiconductor manufacturing method, substrate processing method, and semiconductor manufacturing apparatus. (2004).
- Nitrogen Blanketing of Edible Oils (Part I). Manufacturing.net https://www.manufacturing.net/operations/article/13183952/nitrogen-blanketing-of-edible-oils-part-i (2013).
- Packaging, Inerting and Blanketing. https://www.airproducts.co.uk/applications/packaging-inerting-blanketing-chemicals?gclid=CjwKCAiA2O39BRBjEiwApB2IktziJx6PIz1v1xmKmXoAkzqFX2ClvzEFvVZ0EU7NugSE0Ofa--z59xoCQN0QAvD_BwE.