SS 200 and 300 Series Valves

The 200 series is a class of austenitic(highly corrosion-resistant)stainless steels that are characterized by havinglow nickel content. These are also referred to as chrome-manganese (CrMn) stainlesssteel.

Austenitic steels, which includes both the 200 and 300 series stainless steels, are defined by their face-centered cubic structure. That is, the crystal structure has one atom at each corner of the cube and one in the middle of each face.

Nickel is the most commonly used element to produce this crystal structure, but a post-World War II nickel shortageled to the substitution of nitrogen for nickel in the production of some austeniticcorrosion-resistant steels. The 200 series of stainless steels was born.

While nitrogen alloyed in steel will also form a face-centered cubic structure, it results in harmful chromium nitrides and increases gas porosity. The addition of manganese allows more nitrogen to be safely added, but nickel cannot be completely removed from the alloy. The 200 series stainless steels are, consequently, characterized by their nitrogen and manganese content.

Production and demand for low-nickel stainless steels surged in the 1980s as nickel prices soared and, again, efforts were made to reduce use of the metal.

This led to the development of a huge production increase in India. Asia is now a major source for, and consumer of, this family of steels.

Due to its lower corrosion resistance, the range of applications for 200 series stainless steels is narrower than 300 series steels. It is not recommended for use in chemical environmentsbut has found its way into many household items.

Some applications for 200 series stainless steel include:

• Dishwashers and washing machines
• In-house water tanks
• Indoor and noncritical outdoor architecture
• Food and beverage equipment
• Automobiles (structural)
• Automobiles (decorative)