| 摘要 |
PURPOSE:To enable fluctuation in distance between an object to be inspected and an inspection device to be measured highly accurately and stably by measuring propagation time until reflection signal from a supersonic wave is received from the object to be inspected for each measurement position and then comparing it with a threshold. CONSTITUTION:Transmitters and receivers 1 (1a - 1n) consist of a pair of transducers for transmitting and receiving signal and transmit and receive supersonic wave. A pig is mounted at equal distance along an outer peripheral surface in circumferential direction and runs within a pipe body. Then, a data processing part 4 measures propagation time after supersonic wave is transmitted to an object to be measured until the reflection signal is received for each measurement position 7 and compares it with a threshold which is previously set by a threshold-setting means 9 for specifying an abnormal part. Propagation time at a plurality of measurement positions near this abnormal part is selected 11 and the average value is calculated 12 as a reference value of relative distance between the object to be inspected and the transmitters are receivers 1. Propagation time at the abnormal part is compensated for 13 based on it, thus enabling the state of the abnormal part to detected. |
