Apparatus for detecting surface flaw of pipeline by electromagnetic induction
US4742298A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1986 |
| Grant date | May 3, 1988 |
| Priority date | — |
| Expiry date | Sep 16, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/9046
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting a surface flaw of each pipe constituting a pipeline, including a pig capable of travelling along pipeline and being provided with the following elements: a cylindrical primary coil coaxial with the pipe, the density of a magnetic flux of an AC magnetic field of the primary coil varying in response to an inner surface flaw of the pipe; a plurality of cylindrical secondary coils arranged at prescribed intervals in the circumferential direction of the pipe between a peripheral surface of the primary coil and a confronting peripheral surface of the pipe, each secondary coil having an axis parallel to the axis of the primary coil, and producing an AC voltage proportional to the density of a component parallel to the axis of each secondary coil, of the magnetic flux of the AC magnetic field of the primary coil; and a signal processing circuit for processing the AC voltage signals from the secondary coils to detect the presence and the depth of a surface flaw of the pipe.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.