1. Field of the invention
The invention relates to a method and apparatus for effecting the testing of installed ferromagnetic piping by utilization of an induced magnetic flux.
2. Description of the prior art
Modern refineries, petrochemical plants and well pumping installations represent a veritable maze of installed piping and other tubular elements required to carry fluids through the various steps of the processes involved in such industries. Much of this piping is of ferromagnetic material. In many instances, the fluids carried by the pipes are either highly toxic, flammable or are under high pressure and temperatures so that a breakage of any installed pipe due to internal deterioration of the pipe by corrosion or erosion presents a serious environmental and safety hazard. The oil refining and petrochemical industries have long sought apparatus for effecting the reliable testing of installed ferromagnetic piping to determine in advance when any section of an installed pipe has been internally or externally corroded or eroded to the point where rupture may be anticipated.
A variety of testing techniques have been employed involving magnetic flux leakage methods, ultrasonics and even radiation. Such existing apparatuses, however, are generally expensive to construct and time consuming to operate, so that the inspection expense is a matter of significant economic impact to the particular plant. Moreover, prior art devices have generally required that they be operated by highly skilled and trained technicians, thus further contributing to the high cost of such inspection. Lastly, many of the existing testing devices are effective over only a limited area of the pipe, requiring that the devices be painstakingly scanned over the entire periphery of the pipe requiring movement relative to the pipe in both an axial and a radial direction. In many installations, the pipes are closely adjacent to other pipes or other mechanisms so that the scanning around the periphery of an installed pipe is a virtual impossibility.