Nitric acid
Given that HNO3 is an oxidation agent and that metals and alloys rapidly develop an oxide protective layer, many of them are nitric acid resistant. However, corrosion may be increased as a result of the temperature and acid concentration.
A rise in temperature leads to higher corrosion rates, while concentration variations may increase or reduce them based on the alloying elements.
Tubacexgrades for the nitric acid industry have been expressly designed to withstand extreme environments such as those found in chemical plants. In particular, hostile corrosion conditions can take place in the following heat exchangers:
Cooling chambers / condensers | Corrosion by evaporation /condensation |
Tail gas pre-heaters | Corrosion by condensation |
Water boiler heaters | Corrosion by heating |
Cooling tower coils | Corrosion by chlorides |
Tubacex offers a complete range of products used in the nitric acid industry:
Austenitic stainless steel:
- 304L, 1.4306, UNS30403. Base material with “limited” corrosion behavior. 1.4306 is preferred to 1.4307 as it has lower corrosion resistance.
- 304L NAG, 1.4306S, UNS30403. 304L has been improved with limited residual elements and a dedicated production process at TUBACEX rolling mills, which provides the material with increased corrosion resistance.
- 310L NAG, 1.4335, UNS31002. Improved grade for nitric acid resistance with even less C, P and S.
- 4361, UNS30600. Grade with high Si content for high nitric acid concentration production.
Duplex stainless steels:
- Higher resistance to stress corrosion with enhanced mechanical properties: 1.4362 (UNS S32304), 1.4462, (UNS S32205) or even UNS S32906 for concentrated chloride environments and high mechanical resistance demands.
This complete range of materials has been specifically designed to cover all the nitric acid producers’ needs, thanks to their corrosion resistance properties, as it can contribute to increase the useful life of pipe systems or heat exchanger tubes.
TUBACEX offers all dimensions from 6 mm to 72” OD seamless tubes, fittings and bars (128 mm to 450 mm). Additional sizes are available upon request.