Abstract: A probe for inspecting the inside of a large diameter, substantially vertical, limited access pipe. The probe includes an elongated probe housing having a series of flexible joint along its length to permit the probe to be positioned within the pipe. A plurality of radially extendable guide arms are attached to the lower end of the probe housing for positioning the probe within the pipe and, in the preferred embodiment, a stabilizer weight is attached to the elongated housing adjacent to the guide arms for preventing unstable movement of the probe much like a tail on a kite. In the preferred embodiment, the probe further includes a rotational drive for rotating the plurality of radially extendable guide arms with respect to the elongated housing. In addition, sensors are located on the ends of each guide arm to permit the inside surface of the pipe to be more completely inspected for defects.

Abstract: An apparatus for determining both the axial and angular positions of a defect in a tube wall. The apparatus includes a probe head positioned at the end of an elongated probe carrier having an imbedded orientation indicator. In the preferred embodiment, an encoder measures the angular orientation of the probe head when facing the defect relative to the angular orientation of the carrier and a photodetector and reflective strip measure the angular orientation of the carrier relative to a known orientation. A data processor uses this data to calculate the angular orientation of the probe head and the location of the tube defect.