Abstract
Various protection methods were examined to avoid the corrosion of the mild steel casing in Yachigashira hot-spring (rich in NaCl, CO2; temp. ca. 70°C) near Hakodate, Hokkaido. It was found that the cathodic protection could be successfully used, if proper anode were adopted. According to the results of six month's test, however, it will be more practical to insert the rigid vinyl pipe inside the casing.
