Alloy 28 is a super austenitic stainless steel with very high nickel (31%) and chromium (27%) contents. The molybdenum content is about 3.5%. The alloy is designed for specific purposes, including sulphuric and phosphoric acid applications. It behaves particularly well in sulphuric and phosphoric acid environments, even when contaminated by chlorides and fluorides species. The high nickel content improves its stress corrosion cracking resistance. The combined chromium and molybdenum additions contribute to drastically increase the localized corrosion resistance. Alloy 28 behaves much better than alloy 825 and could be considered in some applications (sour gas) to replace the more expensive 625 grade. The alloy is extensively used in chemical and offshore applications including very sour gas fields.