2002 Volume 51 Issue 5 Pages 227-230
The quality of tap water in West Iburi district (the southern part of Hokkaido) where the moundless pitting has frequently occurred has been investigated. It is found that the electric conductivity of tap water in the pitting area is strongly correlated with total hardness, SO42- and residuals. The electric conductivity in the pitting area shows a high value in winter and a low value in summer. We propose that the electric conductivity in winter will be utilized for an estimation of the pitting occurrence rate. A hazard map for the pitting corrosion of copper tube was drawn using electric conductivity measurement.