Patent ID: 7783432
Filing Date: 2010-08-24
Classification: G01N

Abstract:
1. A method for near-real-time nondestructive testing of pipes made of a magnetizable material for flaws based on leakage flux, comprising the steps of: moving a pipe longitudinally or rotationally, or both, generating a magnetic flux and transferring the magnetic flux contactless into the pipe, scanning the pipe in a helical pattern, detecting with one or more sensors a magnetic leakage flux exiting from a surface of the pipe, said magnetic leakage flux produced by discontinuities located in a region near the pipe surface, converting the detected magnetic leakage flux in near-real-time into processable electrical analog signals, transmitting the analog signals to a pre-amplifier, converting the analog signals into a continuous data stream of digital data, continuously supplying the data from the data stream to a routine for wavelet transformation, performing the wavelet transformation with cascaded digital signal processing routines to produce continuous streams of wavelet coefficients, comparing an evaluation parameter derived from the wavelet coefficients with a reference value to produce a flaw-based signal, associating the flaw-based signal with a position of the flaw, filtering or modifying, or both, the continuous streams of wavelet coefficients, back-transforming the filtered or modified wavelet coefficients into a stream of continuous data by applying an inverse of the cascaded digital signal processing routines, converting the stream of continuous data with a D/A converter into a continuous analog measurement signal, and supplying the measurement signal to an existing analog data acquisition system.