The selection of materials plays a decisive role in the performance and longevity of storage tanks. In industries that require strict hygiene, corrosion resistance, and structural integrity, stainless steel often becomes the primary choice. This material is not a single entity but a family of alloys, each offering distinct properties.
The grade of stainless steel selected for a project directly influences the tank’s ability to hold specific contents, withstand environments, and meet regulatory standards. Engineers and operators are in the position to specify the most appropriate tank stainless steel to use.
The 300 Series
The 300 series, particularly grades 304 and 316, forms the backbone of stainless steel tank manufacturing for a wide range of applications. Grade 304, sometimes called 18/8 stainless for its chromium and nickel content, provides good corrosion resistance and excellent formability. It serves as a general-purpose grade for tanks storing water, certain food products, and chemicals in mild environments.
Grade 316 adds molybdenum to its alloy composition. This addition significantly improves resistance to pitting and crevice corrosion, especially from chlorides and industrial solvents. For this reason, 316 becomes the standard for tanks in coastal areas, pharmaceutical processing, and for storing more aggressive chemical solutions. Its properties justify its common use in applications demanding higher durability.
Specialized Alloys for Demanding Environments:
When standard austenitic grades prove insufficient, manufacturers turn to more specialized alloys. Grade 317L offers higher molybdenum content than 316L, giving it superior performance in harsh chemical processing environments containing sulfuric acid and other aggressive compounds.
For tanks handling very high temperatures or extremely corrosive substances, such as strong acids or bleach, duplex stainless steels like 2205 present a strong option. These grades combine a mixed microstructure, offering strength approaching that of carbon steel but with much better corrosion resistance than standard 316. They effectively resist stress corrosion cracking, a valuable trait in pressurized or heated tank scenarios.
Food-Grade and Sanitary Specifications:
In the food, beverage, and dairy industries, material selection focuses on cleanliness and compliance. While grades 304 and 316 are common, the manufacturing and finishing process receives extra attention. Tanks often use low-carbon variants like 304L and 316L. The “L” designation indicates a reduced carbon content, which prevents harmful carbide precipitation during welding.
This maintains corrosion resistance at weld zones, eliminating potential sites for bacterial harborage. These tanks also feature highly polished, smooth interior finishes to facilitate easy cleaning and sterilization, meeting strict sanitary codes.
