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Showing papers on "Time-of-flight diffraction ultrasonics published in 1987"


Patent
23 Oct 1987
TL;DR: In this article, a time-of-flight diffraction (TOFD) inspection of an under-water object such as an oil-well platform is performed using an ultrasonic transducer.
Abstract: Apparatus (10) is provided for performing time-of-flight diffraction (TOFD) inspection of an under-water object such as an oil-well platform, including means (34, 40, 20) to support two ultrasonic transducers (106, 108) adjacent to the surface of the object but spaced apart from each other, and means (24, 72) to cause one transducer (106) to slide along the surface towards the other transducer (108). A slow speed of about 5 mm/sec is achieved by using the water to damp the sliding motion. The apparatus can be used to size cracks at a welded joint between two members.

11 citations


Journal ArticleDOI
TL;DR: An overview of the major NDT requirements of the offshore industry is presented, and those areas where the development of new techniques is underway are highlighted in this paper, where a review of the projects undertaken by Harwell's Offshore Inspection R&D Service Club is given.
Abstract: An overview of the major NDT requirements of the offshore industry is presented, and those areas where the development of new techniques is underway are highlighted. A review of the projects undertaken by Harwell's Offshore Inspection R&D Service Club is given and one of these, subsea node joint crack sizing using time-of-flight diffraction (TOFD), is described. Finally, a view is given on where the emphasis of future development should be placed.

8 citations


Journal Article
TL;DR: Controle non destructif par ultrasons des tuyauteries et des composants d'enceintes sous pression (diffraction et methode du temps de vol).
Abstract: Controle non destructif par ultrasons des tuyauteries et des composants d'enceintes sous pression (diffraction et methode du temps de vol)

4 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived the signal amplitudes expected with Time-of-Flight Diffraction (TODF) for tilted or skewed cracks for elliptical and strip-like defects of through-wall extent between 15 and 25 mm and at depths from the inspection surface of between 100 and 225 mm.

4 citations


Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, Harwell developed a mini-computer controlled multi-probe defect detection and sizing system based on the ultrasonic time-of-light/diffraction principle introduced by Silk.
Abstract: In 1980–81, Harwell developed a mini-computer controlled multi-probe defect detection and sizing system(l) based on the ultrasonic time-of-light/diffraction principle introduced by Silk(2). This system proved to be capable of fully automatic data collection from the PWR girth-weld simulation Plates 1 and 2 in the Defect Detection Trials of 1981–82. The speed of collection and subsequent analysis was such that a report on the defects found could be filed within 48 hours. The mode of operation adopted simulated minimum time of access to the defects, and was intended to define that dimension of a defect which has greatest significance, ie the through-thickness dimension.

1 citations


Journal ArticleDOI
TL;DR: In this article, a review of nuclear-oriented NDT development work at Harwell is presented, illustrating the synergy between this and the National NDT Centre's non-nuclear program.
Abstract: A review is presented of nuclear-oriented NDT development work at Harwell, illustrating the synergy between this and the National NDT Centre's non-nuclear programme. Most of the work in recent years has been concerned with automated ultrasonic inspection techniques for the proposed Sizewell ‘B’ PWR pressure vessel, and Harwell's part has been to develop the time-of-flight diffraction method (TOFD) as a stand-alone technique for defect detection and sizing. The value of this technique, which originated in the Centre's non-nuclear work, has been amply demonstrated in trials involving thick plate weld and nozzle specimens. Currently the main item in the nuclear programme is the improvement of ultrasonic inspection capability for austenitic castings and welds, for both PWR and fast reactor applications, by means of advanced scanning and signal processing techniques. In examining this and other current interests, the strong influence of theoretical modelling is noted. The development o of automatic defect classification techniques makes use of the image analysis resources at Harwell. Future nuclear-oriented NDT work is expected to extend the current developments, with emphasis on ease of technology transfer, and exploitation of new techniques, including electromagnetic and optical generation of ultrasound.

1 citations