Nitric acid

Nitric acid (HNO3), (source Wikipedia) also known as aqua fortis (Latin for “strong water”) and spirit of niter, is a highly corrosive mineral acid.

The main industrial use of nitric acid is for the production of fertilizers. Nitric acid is neutralized with ammonia to give ammonium nitrate. This application consumes 75–80% of the 26 million tonnes produced annually (1987). The other main applications are for the production of explosives, nylon precursors, and specialty organic compounds.

The corrosive effects of nitric acid are exploited for some specialty applications, such as etching in printmaking, pickling stainless steel or cleaning silicon wafers in electronics.

A solution of nitric acid, water and alcohol, Nital, is used for etching metals to reveal the microstructure. ISO 14104 is one of the standards detailing this well known procedure.

Nitric acid is used either in combination with hydrochloric acid or alone to clean glass cover slips and glass slides for high-end microscopy applications. It is also used to clean glass before silvering when making silver mirrors.

Commercially available aqueous blends of 5–30% nitric acid and 15–40% phosphoric acid are commonly used for cleaning food and dairy equipment primarily to remove precipitated calcium and magnesium compounds (either deposited from the process stream or resulting from the use of hard water during production and cleaning). The phosphoric acid content helps to passivate ferrous alloys against corrosion by the dilute nitric acid.

Nitric acid is oxidizing graphite structure over 50% concentration even at room temperature.

Phenolic resin is not recommended with nitric acid, due to fast corrosion.

GT developed our grade GT FLON which can sustain corrosion over a range of concentration and temperature of 120°C up to ~50% concentration.

GT FLON grade is widely use for stainless still pickling application for mixed acid heater (nitric acid + hydrofluoric acid, see application here)

We can proceed to corrosion test or provide coupon for test on request here.

Equipment frequently used


Materials frequently used


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