Tank Blanketing, or padding, refers to applying a cover of gas over the surface of a stored commodity; usually a liquid. Its purpose is either to protect or contain the stored product or prevent it from harming personnel, equipment, or the environment. In most cases the blanketing gas is nitrogen, although other gases may be used.
Blanketing may prevent liquid from vaporizing into the atmosphere. It can maintain the atmosphere above a flammable or combustible liquid to reduce ignition potential. It can make up the volume caused by cooling of the tank contents, preventing vacuum and the ingress of atmospheric air. Blanketing can simply prevent oxidation or contamination of the product by reducing its exposure to atmospheric air. It can also reduce the moisture content. Gas such as nitrogen is supplied in a very pure and dry state.
The list of products blanketed is extensive - everything from adhesives, catalyst, chemicals, fats and oils, foods, fuels, inks, pharmaceuticals, photographic chemicals, soaps, and water.