JPS55128588A - Electric corrosion-proof bond for metal buried underground - Google Patents

Abstract

PURPOSE: To prevent both metals from corrosion by setting up at our disposal the potential between the second metal and electrode in such a way as to flow current from the second metal buried underground to the first metal buried underground, connected with a conductive line, in electrically preventing metal buried underground, e.g., fluid transport steel pipe, from corrosion.

CONSTITUTION: The fluid transport steel pipes 2 and 3 are buried closely underground 1 and the electric railway rail 4 is laid near these steel pipes. The stray current coming into the steel pipe 2 is directed through the drainage diode 6 from the conductive line 5 toward the rail 4. A base metal of a greater ionization tendency, e.g., the Fe-made electrode 7, is buried in proximity to the steel pipe 3, by which the earth potential of the steel pipe 3 is detected. Since the steel pipe 2 is protected from corrosion by the diode 6, when the current from the steel pipe 2 is drained, as much as the potential E1 is kept smaller than that of the steel pipe 3. The potential of the electrode 7 is as high as the potential E2 above that of the steel pipe 3. When the potential E2 becomes smaller than the predetermined potential V_s, the level discriminating circuit 13 electrifies the circuit 12 to allow current to flow from the steel pipe 3 toward the pipe 2.

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