Patent ID: 6474165
Filing Date: 2002-11-05
Classification: G01N

Abstract:
Apparatus for use in the characterization of a liquid-filled pipe, which apparatus comprises a vehicle capable of fitting inside the pipe and of being transported by the liquid along the pipe, the vehicle carrying rings of several ultrasonic transducers arranged such that during utilization the rings are co-axial with the pipe and spaced along the vehicle, and such thata first ring of transducers operates in the reflection mode purely radially while a second and a third ring of transducers operate as a pair displaced axially to each other, the pair being used in a longitudinal refraction mode in which one ring of the pair emits pulses along the pipe generally at the critical angle to the wallâ€”that is to say, along directions spread in a cone so as to accommodate expected variations in the critical angle of the pipe, liner and debris materialsâ€”such that the wave is refracted as waves traveling within the debris, lining and pipe wall, and the other ring receives the refracted wave, the emit ring of transducers of the refraction mode pair also has the capability of receiving reflected echoes, this being a refraction/reflection mode, and a fourth ring of transducers is used in a circumferential refraction/reflection mode in which each transducer emits pulses in a radial plane but at the critical angle circumferentially to the wall such that the wave is refracted as a circumferential wave along the debris, lining and pipe wall and the ring then receives reflections back along the same path, the vehicle also carrying means for measuring the distance traveled along the pipe, and a collapsible drogue to ensure that in use the flow of liquid provides sufficient drag to produce forward propulsion of the vehicle.