METHOD OF ULTRASONIC CONTROL OF BUTT, LAP AND TEE WELDS OF THIN-WALLED PIPES OF SMALL DIAMETER Russian patent published in 2013 - IPC G01N29/04 

FIELD: measurement equipment.

SUBSTANCE: control zones are scanned with the help of an inclined combined piezoelectric converter (PEC), PEC position is determined, which corresponds to maximum of an echo-signal from a defect, equivalent area of the detected defect is determined, as well as its coordinates. At the same time acoustic probing of the welded joint is carried out with a multiply reflected beam, in process of control they identify the number of rereflections of an ultrasonic beam, speed of a shift ultrasonic wave in a metal is determined with the help of standard samples, besides, speed measurement is carried out using non-lapped PECs, and the operation of calibration of a depth metre of a flaw detector is carried out in special control samples with the help of lapped PECs using the following operations: installation of the PEC onto the control sample at a certain distance from artificial reflectors, control of delay time in a prism introduced into the flaw detector memory, with a pitch of 0.01 mcs, registration of flaw detector depth metre readings at each step of control, determination of actual values of coordinates of artificial reflectors for each scheme of acoustic probing with a single-reflected, double-reflected or triple-reflected beam, measurement of coordinates of artificial reflectors in the control sample with the help of ordinary measurement tools, completion of the process of delay time calibration-control in the prism.

EFFECT: increased accuracy and reliability of defect coordinates detection in process of ultrasonic control of butt, lap and tee welds of thin-walled pipes of small diameter.

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