1992 Volume 41 Issue 3 Pages 169-174
Field tests were done at Onikobe and Minamikayabe geothermal sites and the effect of flow velocity on flow-assisted corrosion damage was clarified as follows: Corrosion rates of stainless steels were very small in the alkaline liquids of Onikobe brine A and Minamikayabe brine, and the flow effect was also very small. The rates of mild steels were large in short test duration, but decreased to 0.01mm/y after 46 hours. The flow velocity at which corrosion rates of mild steels reached to the maximum was larger in Minamikayabe geothermal brine than in Onikobe brine A, because the former contained hard solid particles and less dissolved oxygen than the latter. In Onikobe acid geothermal brine B, corrosion rates of mild steels increased with velocity at 0-0.5m/s, but were constant between 0.5m/s and 4.1m/s. However, in case that the brine contained 5mg/l dissolved oxygen, the rates increased with velocity beyond 0.5m/s.