METHOD FOR EVALUATING FASTENING STATE OF THREADED JOINT OF PIPES OR TUBES AND METHOD FOR FASTENING THREADED JOINT OF PIPES OR TUBES USING THE METHOD

摘要

There is provided a method capable of evaluating a fastening state of a t hreaded joint that is used as a joint of pipes or tubes such as OCTG with a high degree of accuracy even after being fastened and a method for fastening a threaded joint of pipes or tubes using the evaluating method. The present invention provides a method for evaluating a fastening state of a threaded joint of pipes or tubes including a pin having an external thread part, a me tal seal part, and a shoulder part on an outer peripheral surface, and a box having an internal thread part, a metal seal part, and a shoulder part corr esponding to each part of the pin on an inner peripheral surface and being f astened with the pin. The evaluating method according to the present inventi on is characterized by transmitting and receiving an ultrasonic wave to and from a plurality of locations along an axial direction of the threaded joint in at least one of the internal thread part, the metal seal part, and the s houlder part of the box; detecting echo intensities for the plurality of loc ations; and comparing the echo intensities detected for the plurality of loc ations to determine whether the fastening state of the threaded joint is goo d or bad.