Corrosion behavior of steels in Gulf seawater environment

Abstract

Due to the aggressive environment prevailing in and around the Gulf seacoast, the materials of construction are subjected to corrosion of varying degrees. There are many factors influencing the initiation of one or several corrosion processes. These factors include the nature of material, surface finish, temperature, humidity, wind directions, rainfall, etc. Steel is the predominant constructional material in seashore structures including desalination plants which are subjected to general or localized corrosion of varying degrees. A complete systematic information regarding corrosion of materials in Gulf seawater is lacking. Keeping in view the importance of the corrosion data of materials — particularly steels in Gulf seawater — a systematic study on this subject had been initiated in 1990 and was completed in 1996. This paper provides the results of this study concerning the corrosion behavior of steels in Gulf seawater. The materials include stainless steels and super stainless steels (austenitic, ferritic and duplex). The study encompasses the factors influencing general, pitting and crevice corrosion of materials. The effects of TDS in general and chloride concentration in particular and degree of chlorination have been discussed in detail. The role of dominant alloy addition on the corrosion behavior of steels has been emphasized. Weight loss and electrochemical techniques have been employed in determining the corrosion rates of materials. A potentiodynamic polarization technique has been used to evaluate parameters related to localized corrosion. Both exposure and accelerated tests have been carried out to study crevice corrosion attack. Effect of surface finish on crevice attack has been investigated in detail. Rank orders of corrosion rates of steels under different conditions have been presented and their importance concerning materials selection in desalination plants is discussed.