Possessing damage monitor and damage supervisory mannered null supervisory

摘要

PROBLEM TO BE SOLVED: To detect the presence or absence of a damage of a covering member of a covered steel pipe buried in the ground.;SOLUTION: M-sequence signals with a constant voltage are applied between the shell of pipe and an applying electrode buried at a reference position P in the covered steel pipe 1, and the presence or absence of the damage in the covered steel pipe 1 is judged based on the variation of the grounding resistance calculated from the conductivity of the shell, the pipe to pipe potential and the pipe to ground potential detected at every measurement section La-Ln, and the measurement section where the damage is present, is specified based on the variation of the pipe to pipe potential. Then, a distance from the detection point on the side of the reference position P in the measurement section where the damage is present, up to the position of the damage is calculated based on a value of current inside the pipe being calculated from the pipe to pipe potential at the detection points adjacent to both sides of the detection point on the side of the reference position P in the measurement section where the damage is present, the pipe to pipe potential at the detection point on the side of the reference position P in the measurement section where the damage is present, the distance of the measurement section and the conductivity of the shell.;COPYRIGHT: (C)2003,JPO