METHOD AND APPARATUS UTILIZING A TRANSMITTER AND RECEIVER FOR DETECTING THE PRESENCE OF A METALLIC OBJECT WITHIN A PIPE

• US 3,597,680 A
• Filed: 12/19/1968
• Issued: 08/03/1971
• Est. Priority Date: 12/19/1968
• Status: Expired due to Term

• Current Assignee: Merrill K. Haddon
• Original Assignee: Merrill K. Haddon
• Inventors: Haddon, Merrill K.
• Application Number:
  US04/785,117
• Time in Patent Office: 957 Days
• US Class Current: 324/326
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A method and apparatus for exploring an installed, concealed pipe to obtain information such as the location and coarse thereof, and the presence and position of a metallic object lodged therein. The method involves moving an electromagnetic wave transmitter through a pipe with the transmitter operating, and from a point outside the pipe receiving and interpreting the wave transmitted thereto by the transmitter.

Claims

1. A method of detecting the presence of a metallic object located within a pipe comprising through a source of electromagnetic energy disposed within the pipe, producing an electromagnetic wave in a magnetic field, about 80 percent of whose stored energy is within the outer boundaries of the pipe, and whose frequency is influenced appreciably by the proximity of the source to a metallic object inside the pipe, and nonappreciably by the proximity of the source to such an object outside the pipe, transmitting the wave, through radiating the same, to a region outside the pipe, and from a position outside the pipe, observing any changes in the frequency of the wave transmitted to said region with changes in the location of the source an an indication of the presence of the metallic object.

2. Apparatus for exploring an elongated pipe comprising a transmitter adapted to be received for free movement within the pipe operable when energized to produce a magnetic field having about 80 percent of its stored energy disposed within the boundaries of the pipe, and within such field a variable-frequency periodic electromagnetic wave which radiates to a region outside the pipe, the frequency of said wave being influenced appreciably by the proximity of the transmitter to a metallic object inside the pipe, and nonappreciably by the proximity of the transmitter to such an object outside the pipe, and a receiver located outside the pipe adapted to receive a wave transmitted to said region, said receiver including a source operable to produce another wave having a substantially fixed frequency, and indicating means constructed to indicate any change in the frequency of the first-mentioned wave through comparing the frequencies of said first and second-mentioned waves.

3. Apparatus for exploring an elongated pipe comprising a transmitter adapted to be received for free movement within the pipe, operable when inside the pipe and energized to produce and transmit through radiation to a region outside the pipe a periodic electromagnetic wave, with production of such a wave accompanied by production of a magnetic field which contains about 80 percent of its stored energy within a zone disposed inside the outside surface of the pipe, with the frequency of said wave being influenced appreciably by the proximity of the transmitter to a metallic object inside the pipe, and nonappreciably by the proximity of the transmitter to such an object outside the pipe, and a receiver located outside the pipe adapted to receive a wave transmitted to said region, said receiver being constructed to indicate an appreciable change in the frequency of said wave.