Corrosion of mild steel in saturated brine solution

Mild steel because of its cheapness and easy availability is used considerably for the handling and storing of saturated brine solution of pH 10 and above. However in these solutions severe pitting occurs in areas intermittently wetted by the solution. The present investigation was taken up to determine the role of the following variables in controlling corrosion. (a) pH (b) free NaOH and (c) rate of alternate immersion. The results of the tests indicated that with even up to pH of 11.6 or free NaOH content of 3 gm/litre it is not possible to suppress the localised attack under alternate immersion conditions. Increase in the rate of alternate immersion was found to increase the rate of attack. (Mr. K.P. Mukherjee, Junior Scientific Officer; Mr. A.K. Lahiri, Senior Scientific Officer and Dr. T. Banerjee, Deputy Director, National Metallurgical Laboratory, Jamshedpur)