| 摘要 |
<P>PROBLEM TO BE SOLVED: To avoid a direct-current electric corrosion risk or over-anticorrosion risk for a pipeline in an underground potential gradient in which the equipotential surface interval of a central portion is dense but that of a peripheral part is nondense in cathode corrosion prevention of the metallic pipeline which is buried so as to pass through the central portion of the underground potential gradient. <P>SOLUTION: The cathode anticorrosive system for a buried metal pipeline P includes: a coupon 10 which is established near the pipeline P in the central portion of the underground potential gradient and simulates the coating defect of the pipeline; an external power supply 20 connected to the pipeline P and supplying a protective current directed to the area in which the underground potential gradient exists; and a controlling part 30 which controls the output of the external power supply 20 comparing the coupon inflow direct-current electricity density in the coupon 10 with a set value to control so that the above density in the coupon 10 is in a cathode anticorrosive control standard. The controlling part 30 obtains the minimum value I<SB POS="POST">DC</SB><SP POS="POST">min</SP>of the coupon inflow direct-current electricity density every set time to compare the value I<SB POS="POST">DC</SB><SP POS="POST">min</SP>with the set value. <P>COPYRIGHT: (C)2012,JPO&INPIT |
