PREDICTION OF CORROSION RATES IN MARINE STRUCTURES

The corrosion rate of structural steels in the adverse marine environments affects the economic interest of offshore structures since the loss of steel may have significant impact on structural safety and performance. With more emphasis to maintain existing structures in service for longer time and hence to defer replacement costs, there is increasing interest in predicting corrosion rate at a given location for a given period of exposure once the protective coating or cathodic protection is lost. Various corrosion allowances are prescribed for structural members by different standards. There are no studies to determine the appropriate corrosion allowance for offshore steel structures in Malaysia. The objectives of the research were to determine the nature and rate of corrosion in mm/year in offshore tubular member. It also tries to identify whether the corrosion rate is affected by differences in the chemical composition of the steels, microalgae, the immersion depth, salinity and water pollution. Two sets of corrosion coupons of Type 3 Steel consisting of mild steel were fabricated and immersed in seawater. The cumulative corrosion rate of the coupon in mm/ per year is estimated based on the material weight loss with time in service. The results of the study are discussed.