The Materal Corrosion Test Using Small Loop System at Geothermal Power Plant in Japan

Abstract

We carried out the material corrosion in acid fluid at Kakkonda and Yanaizu-Nishiyama geothermal power plant using small loop test system. The loop-test system is about 2 meter depth and 3 meter wide and has three corrosion test place using corrosometer, LPR plobe and coupon test. The test coupon is about 30 mm long and 8mm diameter and we can insert 8 test coupon to loop system. Then the carbon steel, low alloy steel and stainless steel are set in the loop system about 1 day. The corrosion rate is calculated from weight change of coupon. And we made estimation system of corrosion rate using previous data and temperature, pH and metal chemical composition. At Kakkkonda test under pH 3.6 and 145 degree C, the corrosion rate of carbon steel is about 1.49 mm/year and closed to calculated rate from database. But the rate of carbon steel at Yanaizu-Nishiyama under pH 4.9 and 168 degree C is about 0.13 mm/year and less than rate based on database. We show the several material data and the result comparing the database.