Method and apparatus for detecting flaws in the threaded end of an elongate member using electromagnetic excitation and an automated scanning sensor
US4503393A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 5, 1981 |
| Grant date | Mar 5, 1985 |
| Priority date | — |
| Expiry date | Oct 5, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for detecting flaws in the threaded end of a ferromagnetic pipe is disclosed. The apparatus comprises means for applying a magnetic force to produce a field generally axially through the threaded end of the pipe, first and second means adjacent successive crests of a thread for sensing a generally radial magnetic field and generating a first and second signal corresponding to the sensed magnetic fields, and means for differentially connecting the signals generated by said first and second sensing means, whereby a differential output signal is produced in response to a flaw between the crests of the thread being inspected. The apparatus also comprises means for helically rotating said sensing means to follow a path corresponding to the threads of the pipe, whereby the first and second signals vary with time. A method for detecting flaws in the threaded end of a ferromagnetic pipe is also disclosed. The method comprises the steps of applying a magnetic force to produce a field generally axially through the threaded end of the pipe, sensing the radial magnetic field adjacent successive crests of a thread of the pipe, generating first and second signals corresponding to the s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.