PROCESS DETECTING FLAWS, PREDOMINANTLY CORROSION DEFECTS, IN PIPE-LINES Russian patent published in 2004 - IPC

FIELD: nondestructive inspection of pipe-lines, instrumentation. SUBSTANCE: process detecting flaws in pipe-lines consists in placement of pair of acoustic transducers on ends of tested section of pipe-line. One transducer in each pair records longitudinal oscillations and another transducer registers lateral vibrations. Oscillations generated by flaw are recorded by all transducers simultaneously with their subsequent filtration to isolate signals with frequency of 1000-2500 Hz; signals of acoustic transducers in each pair are compared with one another to extract signals from flaws. Signals from transducers of longitudinal oscillations generated by flaw are converted to digital codes, high-frequency phase oscillations are modulated by digital code from one transducer, phase-shifted signal is power amplified, emitted into the air, detected at another end of tested section of pipe-line, multiplied and divided by phase in two, harmonic voltage is extracted, its initial phase is stabilized, multiplied with phase-shifted signal, modulating digital code is derived, delayed in time, multiplied with another digital code, cross correlation function of digital codes is isolated, delay time is varied till maximal value of cross correlation function is achieved, maximal value of cross correlation function is maintained by automatic change of delay time, delay time is recorded, position of flaw in tested section of pipe-line is established and recorded. EFFECT: enhanced productivity of process, increased length of sections of pipe-line diagnosed reliably. 2 dwg