The materials used in the construction of individual units of a chemical plant are extremely varied, steels, non-ferrous metals, and non-metals to name a few. While carbon steels for general structural use comprise the greater part of the construction materials, heat-resisting materials and high-strength materials are also frequently used, depending upon the temperatures, pressures and operating conditions involved. In some cases, corrosion resisting materials are used to prevent corrosion in environments which are corrosive because of the chemical composition of the fluids handled. Such corrosion resisting materials are typically represented by types 304 and 316 austenitic stainless steels.