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

摘要

Disclosed is a method which can evaluate the connection state of the shoulder portion of a screw coupling used as a coupling in pipes such as oil well pipes, where said evaluation occurs during or after connection in a simple and precise manner. The method for evaluating the connection state of a pipe thread coupling (100) is characterized by transmitting an ultrasound surface wave from the inner surface of either a pin (1) or a box (2), across the shoulder portion (13, 23) of the pin (1) or box (2), towards the inner surface of whichever of the pin (1) or box (2) which is not where the surface wave originates, and determining the quality of the connection state of the pipe thread coupling (100) based on the strength of the transmitted wave or the strength of the reflected wave.