Materials of construction for the chemical process industry (CPI) must resist uniform corrosion and have sufficient resistance to localized corrosion such as pitting, crevice corrosion and stress corrosion cracking. Corrosion data from the literature and corrosion tables are not sufficient for material selection for chemical plants. Simulated corrosion testing in the laboratory, testing in pilot or reference plant is necessary for validation. Which standard tests are helpful and how to use and interpret their results is another aspect to consider. In addition, further aspects like mechanical stability, fabricability, safety, testing, cost efficiency, etc. have to be considered in the process of material selection so that at the end the material properties match the requested material requirements in the best way. Over the past 50 years, improvements in alloy metallurgy, melting technology, and thermomechanical processing, along with a better fundamental understanding of the role of various alloying elements have led to many different nickel alloys which are available for use in severe corrosive environments of the chemical process industry. On the other hand new chemical processes, more stringent environmental regulations, higher temperatures and pressures, more corrosive catalysts, multipurpose use and flexibility to handle different feed stock and upset conditions pose new challenges in the material selection process requiring the right approach. The aim of this paper is to review the main aspects of the material selection for the process industry and present different examples to illustrate the material selection process.
Keywords: nickel alloys, material selection, material properties, corrosion, corrosion tests