For applications involving highly corrosive environments due to the presence of chemically aggressive media, e.g. for equipment and plants which are cooled by seawater and parts for offshore plants. In the chemical industry where resistance to the attack of pure acids as well as acids containing chloride ions (sulphuric acid in particular), of organic acids and mixed acids is required in the higher pressure and temperature ranges. The enhanced resistance to crevice corrosion permits use also for applications where incrustation must be expected, and / or where the formation of gaps cannot be avoided by design precautions.