Corrosion behaviour and biofouling characteristics of structural steel in the coastal waters of the Gulf of Mannar (Bay of Bengal), India

Abstract

The corrosion behaviour and biofouling characteristics of structural steel coupons at three different locations in the Gulf of Mannar were studied over a period of 2 years. Oyster fouling was predominant at Tuticorin open sea, while barnacle fouling was more pronounced at Mandapam and Tuticorin harbour. Among the three locations, Tuticorin open sea showed a markedly higher biomass, particularly after 12 and 18 months. The extent of crevice corrosion caused by hard foulers was more pronounced at Tuticorin harbour when compared to that at the other two locations. The corrosion rate of the structural steel coupons for 24 months was in the order, Mandapam > Tuticorin harbor > Tuticorin open sea. The loss in tensile strength at 12 and 24 months was in the order, Tuticorin open sea > Tuticorin harbor > Mandapam. The corrosion behaviour of the structural steel coupons was strongly influenced by the variations in the biofouling assemblage at the three different coastal locations.

Keywords:

• structural steel
• polarization
• weight loss
• crevice corrosion
• tensile strength
• fouling organisms
• coastal waters
• water quality

Acknowledgements

The authors wish to thank the Director, the Central Electrochemical Research Institute, Karaikudi for permission to communicate the results. The enthusiastic technical service rendered by Mr P. Ganapathy, Senior Technical Officer, CECRI Unit, Tuticorin is thankfully acknowledged. The authors also wish to thank the Ministry of Environment and Forests, New Delhi for financial support (Project Grant No.19-26/2003-RE), and the three anonymous reviewers are thanked for their valuable comments and criticisms.