| 摘要 |
A system for inspecting in-service gas distribution mains is disclosed. Coiled tubing technology and magnetic flux leakage (MFL) technology are integrated to produce a new inspection system for low pressure, in-service distribution pipelines. The coiled tubing provides the means by which an inspection module employing MFL technology is inserted into, moved through, and removed from an in-service pipeline. A portable inspection system can thereby be moved to a desired location on a trailer. The sensor module comprises a plurality of magnet assemblies each having a Magnet N out, a Magnet S out and a magnet core, the magnet assemblies being conical in shape and being arranged into a circular array. The magnet array diameter is smaller than that of a pipe to be inspected, thus defining a radial air gap. The magnet array being constructed and arranged to provide a magnetic circuit having sufficient strength so as to be operable through the radial air gap. A centering mechanism is constructed and arranged to maintain the sensor module in concentric relation with the pipe to be inspected. This array provides an efficient method of packing the magnets to generate the very powerful magnetic field desired. The conical shape of the magnets in this assembly permits the unit to negotiate tighter bends than would be possible with a cylindrical assembly. The centering mechanism permits product bypass and minimizes removal of surface debris. |
