Volume 29, Issue 3-4

Sulfidic corrosion of steels in refineries is a prevalent phenomenon that occurs in oil containing sulfur species between 230°C and 425°C. There are several internal and external variables controlling the occurrence of sulfidic corrosion. The most important external factors are temperature, concentration and type of sulfur species, and presence of naphthenic acid. The most important internal or metallurgical factor to control sulfidic corrosion is the amount of chromium in the steel. The refinery industry relies today in a vast industrial experience on the variables affecting sulfidic corrosion but very little is known on the basic mechanism of attack. There is ample room for research and the basic understanding of this phenomenon.

High throughput screening (HTS) and its associated experimental methods represent an efficient approach to explore multi-variable processes, such as corrosion and corrosion mitigation. The gain in efficiency when using the HTS approach is possible only through the judicious selection and integration of materials, methods, and instrumentation. This paper examines some of the critical topics when developing an HTS corrosion study, such as substrate selection and preparation, sample presentation, electrochemical cell design, instrumentation, electrode design, and assay selection. Due to the similarity between the questions raised within corrosion investigations and within other areas of electrochemistry, the HTS literature will be examined from a broader perspective.

The chemically aggressive environment generated in some parts of equipment at multi-stage flash (MSF) desalination plants can cause corrosion problems. The proper selection of materials with higher resistance to corrosion is considered as one of the most prospective approaches for smooth and efficient running of the plants. Because of this, the study of the corrosion behavior of selected materials is an important issue in the realm of desalination technology. This paper reviews the performance of materials used in different MSF desalination plants. The corrosion behavior of materials in different sections of plants, under surrounding environmental conditions, is discussed. Various types or forms of corrosion occurring in different units of plant are described and the strong role of local attack is emphasized. Case histories dealing with failure of components in different plants are cited. The criteria for the selection of materials, which depend upon the nature of environment and operating conditions, are exemplified. The merits and demerits of materials currently employed are highlighted and introduction of new materials either in existing plants as the possible replacements or in future plants are discussed.