Influence of fouling assemblage on the corrosion behaviour of mild steel in the coastal waters of the Gulf of Mannar, India

Abstract

Corrosion behaviour and biofouling characteristics of mild steel in three different coastal locations in the Gulf of Mannar, India have been studied over a period of 24 months. Oyster fouling was predominant at Open sea — Tuticorin, while barnacle fouling was dominant at both Mandapam and Harbour — Tuticorin. The rate of corrosion for 24 months exposure period was highest at Mandapam, where fouling was minimal. The surface of the mild steel was characterized by etchings & crevices beneath the hard foulers attached on it, at all the test locations. The depth of crevice caused by hard foulers was higher at Open sea — Tuticorin followed by Harbour — Tuticorin and Mandapam. The loss in ultimate tensile strength was more in Open sea — Tuticorin than the other two locations. Corrosion behaviour of mild steel is discussed based on the variation in the biofouling assemblage at the three test locations.