Kawasaki Steel Corporation

Kawatetsu Techno-construction Co., Ltd.

Toshikazu Masuda

Toshio Osada

Akira Adachi

Tomoya Fujimoto

Isamu Miyoshi

Shinji Gotoh

A coating fault locating technique transmits a base electric signal from a power source to a buried metal pipe. A location of a coating fault in the buried pipe is detected by detecting a gradient of a changing magnetic field between two points spaced along the buried pipe. The gradient is detected based upon the output differential of at least one pair of search coils. The gradient is caused by a leakage of current that occurs at the coating fault. In particular, the at least one pair of search coils are provided in a mobile unit that is located above ground. The at least one pair of search coils are spaced apart from one another and have their axes arranged so as to have a low sensitivity to a magnetic field generated by the base electric signal running through the buried pipe. The at least one pair of coils are spaced apart from each other such that a line drawn between midpoints of the search coils' axes crosses a plane normal to the axis of the buried pipe. For example, the at least one pair of search coils are spaced from each other horizontally, with each coil arranged with its axis extending in a vertical plane. The data detected by the search coils in the mobile unit can be transmitted to a GPS system, which then generates a map identifying the locations of any detected coating faults.

Method and apparatus for locating coating faults on buried pipelines

A buried pipe laying method of additionally coupling a new pipe with the extreme end of a buried pipe laid underground involves flatly deforming a cylindrical pipe having a pipe length smaller than the inside diameter of the buried pipe, conveying the deformed cylindrical pipe to the extreme end of the buried pipe laid underground through the interior thereof, and then returning the deformed shape of the cylindrical pipe to its original circular shape and coupling it with the extreme end of the buried pipe.

Buried pipe laying method

Growing community of inventors

Tokyo, Japan

Toshikazu Masuda