Laboratory evaluation of ozone as a corrosion inhibitor for carbon steel, copper, and galvanized steel in cooling water
- Wuhan Univ. (China)
- Clarkson Univ., Potsdam, NY (United States). Dept. of Chemical Engineering
- Diversey Water Technologies, Inc., Chagrin Falls, OH (United States)
An experimental study has been made to evaluate ozone as a corrosion inhibitor for use in cooling water systems. Corrosion of AISI 1010 carbon steel, CDA 122 copper, and hot-dipped galvanized steel in soft and hard water containing 0 to 0.1 ppm of ozone was examined at 90 F over a range of water velocity of 0.5--9.5 ft/s. The mechanism of ozone affecting metal corrosion was studied with an electrochemical polarization technique and the change in the chemical composition of test water during the corrosion tests. It was found that in soft water corrosion of carbon steel was inhibited by ozone. The corrosion rate of carbon steel in soft water was: 22--60 mpy without ozone and 14--27 mpy in the presence of 0.1 ppm of ozone. Pitting corrosion occurred on all carbon steel coupons in soft water; ozone decreased pit density, pit size and pit depth. In hard water, corrosion of carbon steel was accelerated by ozone. Uniform corrosion occurred on all carbon steel coupons in hard water. The extent of corrosion acceleration by ozone decreased with increasing water velocity; at a high velocity of 9.5 ft/s the corrosion rates of carbon steel with and without ozone became approximately the same at 20 mpy. Corrosion of copper in both soft and hard water was accelerated by ozone. In the presence of 0.1 ppm ozone, the corrosion rate of copper was: 0.6--1.5 mpy in soft water, and 0.8--1.4 mpy in hard water. Corrosion of galvanized steel in both soft and hard water was inhibited by ozone. The inhibition efficiency increased with increasing water velocity.
- OSTI ID:
- 392468
- Report Number(s):
- CONF-960254--
- Country of Publication:
- United States
- Language:
- English
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