Patent ID: 7159477
Filing Date: 2007-01-09
Classification: G01B

Abstract:
1. An apparatus for measuring deformation of a surface of a pipe comprising a single detector capable of directly detecting changes in the radius of a pipe and a plurality of guides for guiding the detector along the pipe in a direction parallel to a longitudinal axis of the pipe, the guides comprising rotatable members spaced apart from the detector and arranged to contact a surface of the pipe when the detector is in contact with the pipe, wherein said guides are respectively provided on each side of the detector, the rotatable members of the guides and the detector being positioned substantially along an arc such that in use, the detector and the guides are in contact with the pipe surface at different points around its circumference, and a circumferential distance between each said rotatable member of the guides and the detector being smaller than a radius of the arc, whereby an output related to the deformation of the pipe surface is derived only from the output of the single detector.