Analytical assessment of corrosion inhibitors for Cupro nickel (70:30) and Monel-400 used in the process cooling water systems

The protective coatings formed on Cupro-nickel (70:30) and Monel-400 surfaces on exposure to process cooling water environment containing de-mineralised water (DMW) with different corrosion inhibitors such as hydrazine (N2H4), hydroxy ethylidene di-phosphoric acid (HEDP) and sodium dichromate Na2Cr2O7) at alkaline pHs are expected to be complex in nature. Sophisticated analytical techniques such as electron spectroscopy for chemical analysis and X-ray diffractometry have been used for the identification and characterisation of these films and in turn for assessing the suitability of the inhibitors for use in the OCW systems of the Nuclear power plants. (NPP). A detailed account of the experimental findings has been presented and the results have been discussed and analysed in the light of the kinetics of the corrosion and corrosion inhibition processes prevalent in the system. Based on the results obtained, it has been concluded that hydrazine is the best alternate to chromate treatment closed loop PCW systems of NPPs.