Method and apparatus for measuring the wall thickness of insulated pipe

Abstract

A method and apparatus for measuring the wall thickness of insulated pipe of various sizes, shapes and locations without requiring removal of the insulation. The apparatus includes a source which emits a collimated beam of low-level radiation and a detector adapted to detect the beam. The source and detector are pivotally mounted on trucks which in turn are movably mounted on frame assemblies which include rotatable shafts. Stepping motors are mounted on the frame assemblies and are drivingly connected to the shafts for rotating the shafts. Indexer devices are connected to a computer and to the motors for controlling the rotation of the shafts. Motion translators are mounted on the trucks and are operatively connected to the shafts for translating the rotational motion of the shafts into linear motion. The source and detector are located in aligned, opposed spaced relationship adjacent to the pipe. The stepping motors simultaneously linearly move the trucks, and the source and detector mounted thereon, in discrete linear steps along the shafts for scanning the pipe to take discrete measurements of the pipe wall thickness. The radiation beam emitted by the source passes through the insulated pipe and is detected by the aligned detector at each discrete step. A single channel analyzer device connected to the detector measures counts of unattenuated radiation beams detected by the detector. A computer is connected to the single channel analyzer through an interface and generates computer profiles of the pipe wall thickness.