CORROSION OF METALS AND ALLOYS IN THE COASTAL AND DEEP WATERS OF THE ARABIAN SEA AND THE BAY OF BENGAL

Corrosion rate of mild steel, stainless steel, copper, brass and cupro-nickel has been determined by exposing metallic coupons in coastal and oceanic waters of the Arabian Sea and Bay of Bengal. Two stations each in the Bay of Bengal and the Arabian Sea were selected for deep water exposure, whereas, a single coastal station was selected in the Arabian Sea on the west coast of India. Amongst the metals and alloys under study mild steel exhibited highest rate of corrosion. Stainless steel showed negligible corrosion rate in deep waters, whereas has been severely pitted due to macrofouling in coastal waters. In general the corrosion rates for all the metals and alloys under study are found to be higher for coastal waters than in deeper waters except, in case of brass. No significant difference in the corrosion rate of brass has been observed with respect to the depth. The observed order of corrosion rate is MS>Cu>Cu-Ni.>Br>SS in coastal waters and MS>Cu-Ni>Br>Cu>SS in deep oceanic waters.