System for inspecting welded joints in pipe lines by means of ultrasonic waves

Claim 1

System for inspecting circumferentially welded joints in pipe lines and the like using ultrasonic waves, comprising a multi-channel ultrasonic device including switching means for selectively exciting multiple ultrasonic wave generating crystals, manipulation means having a control unit and at least a set of ultrasonic probes, and a recorder, the manipulation means being approximately circular and adapted to be positioned around the pipe line and the set of ultrasonic probes being attached to said manipulation means such that the probes are pressed against the outer wall of the pipe near the welded joint, said probes providing multiple crystals angularly disposed to inspect various portions of the weld which, combined, constitute the entire weld, the crystals in each probe being activated by the multi-channel ultrasonic device through the switching means for transmitting ultrasonic waves into the pipe material and for receiving the reflected waves, which reflected waves are processed by the ultrasonic device and registered by the recorder, the set of ultrasonic probes further including crystals located to direct and receive longitudinal ultrasonic waves reflected from the pipe interior surface to measure pipe thickness, and said switching means comprising means defining gates enabling angled crystals for receipt of transverse ultrasonic waves reflected from weld defects, the gates being timed on the basis of measured thickness, angle of each said transverse wave and its propagation speed in order to avoid recording of reflections due to weld geometry.

Claim 14

The method of inspecting circumferentially welded joints in pipe lines and the like using ultrasonic waves, comprising the steps of providing a set of ultrasonic probes including multiple angularly disposed ultrasonic wave generating crystals, locating a manipulator in parallel relation to the weld, moving the probes with respect to the weld by means of the manipulator, selectively exciting the ultrasonic wave generating crystals, by switching crystal excitation signals among the crystals, measuring the thickness of the pipe by determining the time of an ultrasonic longitudinal pulse reflected from the pipe inside surface, selectively receiving reflected transverse waves at the crystals by controlling the crystal reception times relative to the propagation times based on the measured thickness, angle of each transverse wave and its propagation speed and producing a visual indication of the reception by the crystals relative to displacement along the weld, said step of selectively receiving further comprising limiting the reception of ultrasonic reflections so as to exclude reflections from geometric weld features.

Claim 15

The method of inspecting circumferentially welded joints in pipe lines and the like using ultrasonic waves, comprising the steps of providing a set of ultrasonic probes including multiple angularly disposed ultrasonic wave generating crystals, locating a manipulator in parallel relation to the weld, moving the probes with respect to the weld by means of the manipulator, selectively exciting the ultrasonic wave generating crystals, by switching crystal excitation signals among the crystals, measuring the thickness of the pipe by determining the time of an ultrasonic longitudinal pulse reflected from the pipe inside surface, selectively receiving reflected transverse waves at the crystals by controlling the crystal reception times relative to the propagation times based on the measured thickness, angle of each transverse wave and its propagation speed and producing a visual indication of the reception by the crystals relative to displacement along the weld, said step of selectively receiving further comprising limiting the reception of ultrasonic reflections so as to exclude reflections from geometric weld features.