Corrosion and Biofouling Characteristics of Mild Steel in Mandapam Waters

摘要

Materials submerged in the ocean undergo physical, chemical, and biological surface changes. Marine fouling organisms adhere to structures in the ocean, and this can affect corrosion.1-2 A detailed account of the different fouling organisms and their effects on corrosion appeared in 1948.3 Since then, a number of workers have contributed to this topic, with reference to shallow water,4-5 offshore,6-7 deep ocean,8-9 shipping,10 and estuarine environments.11 Acceleration and long-term inhibition of corrosion by marine organisms have been demonstrated.4 Data also indicate the protective nature of fouling organisms.5 This article describes the effect of fouling on the corrosion rate of steel in Mandapam waters. Algae species were seldom encountered on monthly exposure panels. A dense mat of fouling organisms composed of algae and barnacles occurred in cumulative exposure, however. The annual corrosion loss of mild steel in Palk Bay water is 0.152 mmpy with a fouling load of 0.89 kg/m~(-2). Gravimetric tests indicated that the effect of micro-fouling on the corrosion rate is not significant. Macro-fouling enhances the corrosion rate by two to four times in natural seawater. Polarization studies revealed that the effect of micro-fouling on the corrosion rate of mild steel is significant and the rate increases with time.