The difference between 304 and 316 stainless steel pipe primarily comes down to chemical composition and corrosion resistance. Both are austenitic stainless steels and are among the most widely used grades, but they have distinct properties making them suitable for different environments.
Type 304 Stainless Steel: This is the most common grade of stainless steel, known for its excellent combination of corrosion resistance, formability, and weldability. Its nominal composition includes about 18% chromium and 8% nickel. 304 stainless steel offers good resistance to atmospheric corrosion, oxidation, and a wide range of chemicals found in food processing, dairy, brewing, and general industrial applications. However, it is susceptible to pitting and crevice corrosion in chloride-rich environments, such as coastal areas or applications involving brine solutions.
Type 316 Stainless Steel: Similar to 304, Type 316 contains high levels of chromium and nickel, but with the crucial addition of molybdenum (typically 2-3%). This molybdenum content significantly enhances its corrosion resistance, particularly against chlorides and other industrial solvents. 316 stainless steel pipe is considered superior in marine environments, chemical processing plants (especially those handling chlorides), pharmaceutical manufacturing, and medical implants. While offering better corrosion resistance, 316 is generally more expensive than 304 due to the added molybdenum and sometimes higher nickel content.
In summary, choose 304 for general-purpose applications with good corrosion resistance needs in non-saline environments. Opt for 316 stainless steel when superior corrosion resistance, especially against chlorides, is required, despite the higher cost.