Stainless steels and nickel alloys are widely used because of their resistance to aqueous corrosion but they are families of alloys that also have grades that are most useful at elevated temperatures. Generally “high temperature” is considered to be above 500 Deg C. While each grade may have its own “upper limit”, very few may be used at 1200 Deg C. The operating or design temperature is important in as much as it impacts on the 3 considerations listed below and grade selection must take this in to account.