抄録
We investigated the degree of internal corrosion in 142 pipe samples taken from three buildings undergoing demolition in the Tokyo area. The pipe samples were examined visually and microscopically, measured for wall thickness and degree (percentage) of rust clogging, and analyzed for corrosion products. By application, the overall degree of corrosion for galvanized steel pipe was ranked (in order of decreasing severity) as : (1) hot water; (2) water, waste-water; (3) water used in heating and cooling systems; (4) water used in cooling systems; (5) cooling water, fire-fighting water, air; (6) gas. Feed-and waste-water mains were more corroded than their branches; furthermore, on the branches, corrosion tended to decrease the farther out from the junction. Cross pipes tended to be more corroded on the bottom than on the top. The degree (percentage) of rust clogging tends to be greater in cases where pipes are small in diameter, average corrosion level is significant and usage time is long.
