Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
1996-01-03
2001-05-15
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S644000, C073S592000, C606S015000
Reexamination Certificate
active
06230568
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to ultrasonic imaging and deals more particularly with the use of ultrasonic techniques for the inspection of areas to which access is restricted.
BACKGROUND OF THE INVENTION
In a variety of industrial processes, there are areas that are inaccessible and yet at the same time critical to the process. For example, pipes which conduct the flow of process fluids are often embedded in concrete or a similar material such that inspection of critical pipe joints is impossible. If a faulty weld exists or if a critical area should otherwise fail while the pipes are in service, the lack of ability to carry out inspections creates a situation where no warning is given of a possibly dangerous condition. As an example, in a nuclear power plant or other critical facility, if piping which conducts cooling fluid should leak, disastrous consequences can follow. If the piping is capable of being inspected on a regular basis, the problem can be detected early enough to allow corrective action to be taken before there is a complete failure.
Similar situations arise as to pipes and fittings that are submerged in storage tanks for petroleum based liquids and other types of liquids. Access to submerged areas is restricted if not precluded altogether, so leaks and other problems can arise without any warning because inspections of the submerged areas are not practical and perhaps not even possible. The same problems are presented as to inspections in hostile environments such as areas exposed to the high levels of radiation or toxic chemicals.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus for carrying out ultrasonic inspections and examinations of locations that are normally inaccessible and thus not subject to inspection. By way of example, through the techniques employed by the present invention, a critical pipe weld which is embedded in a concrete slab can be inspected while the piping remains in service. Accordingly, signs of problems in the weld can be detected before they become so great that the weld fails. In addition, submerged components and structures located in hostile environments can be inspected to detect problems before they have developed to the point of complete failure.
In accordance with the invention, a waveguide for transmitting ultrasonic signals takes the form of at least one and usually a number of quartz fibers arranged in a bundle. In the case of a pipe weld or other critical part which is embedded in concrete or another material, the waveguide may also be embedded with one end adjacent to the weld that is to be inspected and the other end situated at the surface of the concrete or at another accessible location. A conventional ultrasonic transducer can be permanently or detachably connected to the accessible end of the waveguide and used to transmit ultrasonic signals and receive signals that are reflected back to the waveguide from the critical weld. In this manner, an ultrasonic image can be generated of the critical area and examined to give a warning of any problems that may exist.
In the case of a part that is submerged well below the surface of a liquid, the waveguide can be manipulated in the liquid using conventional techniques to position its end adjacent to the submerged part. Then, an ultrasonic transducer system above the liquid can be used to apply signals to the waveguide and receive reflected signals in order to provide an ultrasonic image of the part. The image that is generated can be examined for signs of damage or impending failure. The fibers can include some which transmit ultrasonic signals, others which are used for illumination of the tip end of the waveguide, and still others which transmit optical images. With the use of a video monitor, the operator of the apparatus can actually observe on the monitor how the waveguide tip is positioned relative to the part that is undergoing inspection. In many situations, this can enhance the accuracy of the procedure and the overall effectiveness of the inspection process.
It is an important feature of the invention that the ultrasonic waveguide is flexible. This allows it to be manipulated to provide access to areas that are at best difficult to reach with conventional rigid waveguides. The considerable length of the waveguide also provides it with the capability of making relatively remote areas accessible for inspection.
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Zeiss Publication and Translation.
“Similarities and Differences Between Fiber Acoustics and Fiber Optics” C.K. Jen, Dated 1985.
Brunk John A.
Winston Thomas R.
Armstrong Teasdale LLP
Fayyaz Nashmiya
Ultrasonic Sensing and Monitoring Systems, Inc.
Williams Hezron
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