TOFD check process for inner wall defects of nuclear power thick-wall austenite steel pipelines

TLDR: In this article, a TOFD check process for inner wall defects of nuclear power thick-wall austenite steel pipes is described, where a relatively large probe diameter is adopted to improve the measurement precision and resolution of the defects at the inner wall.

Abstract: The invention discloses a TOFD check process for inner wall defects of nuclear power thick-wall austenite steel pipes. According to the TOFD check process, 10-degree probes are used; the control process comprises the following steps: 1) adjusting the distance between the probes to ensure that TOFD acoustic beams are focused at the inner wall of a pipeline; 2) adopting a relatively large probe diameter; 3) selecting a relatively low probe frequency; 4) respectively carrying out off-center parallel scanning on two sides of the weld joint; 5) processing the formed image according to a synthetic aperture focusing technology. According to the TOFD check process, 10-degree probes are used so that the signal attenuation is relatively small; a relatively large probe diameter is adopted so that benefit is brought to improve the measurement precision and resolution of the defects at the inner wall; a relatively low probe frequency is used so that the acoustic wave can achieve the inner wall without too large attenuation; off-center scanning is respectively carried out on two sides of the weld joint, so that the dead zones at the weld joint of the inner wall can be eliminated; the formed image is processed by a synthetic aperture focusing technology, so that the error can be reduced.