Method and device for testing pipes in a non-destructive manner

US7728586B2 · kind B2 · utility

Assignee

• V & M DEUTSCHLAND GMBH · DE

Inventors

• Michael Kaack · Bochum, DE
• Stefan Nitsche · Seelow, DE
• Thomas Orth · Bad Hersfeld, DE

Key dates

• Filing date: Jun 10, 2005
• Grant date: Jun 1, 2010
• Expiry date: Mar 21, 2027

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/87
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The present invention pertains to a method for the nondestructive testing of pipes made of ferromagnetic steel by means of a stray flux, in which the pipe, which is moving in the longitudinal direction and alternatively additionally rotating, is magnetized by a constant field, and the generated magnetic flux is transmitted into the pipe in a contactless manner, and the flaws that are located in the near-surface area of the outer or inner surface of the pipe bring about magnetic stray fluxes, which emerge from the pipe surface and are detected by means of sensors. The amplitudes, preferably of the horizontal field component of the magnetic stray flux, which vary in the vertical direction, are detected, on the one hand, at a near-surface distance from the pipe outer surface, and, on the other hand, at a distance lying further remotely therefrom, and the detected signals are related to one another.