Type 304 | The most common of austenitic grades, containing approximately 18% chromium and 8% nickel. It is used for chemical processing equipment, for food, dairy, and beverage industries, for heat exchangers, and for the milder chemicals. |
Type 316 | Contains 16% to 18% chromium and 11% to 14% nickel. It also has molybdenum added to the nickel and chrome of the 304. The molybdenum is used to control pit type attack. Type 316 is used in chemical processing, the pulp and paper industry, for food and beverage processing and dispensing and in the more corrosive environments. The molybdenum must be a minimum of 2%. |
Type 317 | Contains a higher percentage of molybdenum than 316 for highly corrosive environments. It must have a minimum of 3% “moly”. It is often used in stacks which contain scrubbers. |
Type 317L | Restricts maximum carbon content to 0.030% max. and silicon to 0.75% max. for extra corrosion resistance. |
Type 317LM | Requires molybdenum content of 4.00% min. |
Type 317LMN | Requires molybdenum content of 4.00% min. and nitrogen of .15% min. |
Type 321 Type 347 | These types have been developed for corrosive resistance for repeated intermittent exposure to temperature above 800 degrees F. Type 321 is made by the addition of titanium and Type 347 is made by the addition of tantalum/columbium. These grades are primarily used in the aircraft industry. |