1997 Volume 46 Issue 12 Pages 783-788
Effect of residual chlorine (R-Cl) on the corrosion behaviors of type 304 and 316 stainless steel tube weldments in hot water was investigated in this paper. The spontaneous potential, ESP, measurements for the weldments and long-term loop tests were conducted in hot waters containing several levels of R-Cl at 80°C. R-Cl concentration had a strong effect on ESP values. The noblest ESP values, ESP, max, were no more than 100mV (Ag/AgCl) in DO (Dissolved Oxygen)-saturated hot water without R-Cl, however, ESP, max values were ennobled up to 310-440mV(Ag/AgCl) by addition of 1.0mg/LR-Cl. After an immersion in a long-term looping test, stainless steel tubes were covered with reddish-brown corrosion products film on the inner surface. The corrosion products film brought ESP values approx-imately 110-160mV (Ag/AgCl) nobler in hot water containing 1.0mg/LR-Cl. These facts indicate that not only R-Cl but also corrosion products film make ESP of welded stainless steel nobler in hot water.
