METHOD FOR EVALUATING CONNECTION STATE OF PIPE THREAD COUPLING, METHOD FOR PIPE THREAD COUPLING CONNECTION, AND DEVICE FOR EVALUATING CONNECTION STATE OF PIPE THREAD COUPLING
The present invention provides a method which allows simply, easily and accurately evaluating the fastening state of shoulder parts of a threaded joint for use as a joint of pipes or tubes, such as OCTG, during fastening or after fastening. The fastening state evaluation method for a threaded joint 100 of pipes or tubes according to the present invention is characterized in that it transmits ultrasonic surface waves from the internal surface of either one of the pin 1 and the box 2 toward the internal surface of the other one of the pin 1 and the box 2 through the shoulder parts 13, 23 of the pin 1 and the box 2, and on the basis of the transmitted wave intensity or the reflected wave intensity thereof, determines whether or not the fastening state of the threaded joint 100 is satisfactory.
