Computerized radiographic weld penetration control with feedback on weld pool depression

Computerized radiographic weld penetration control with feedback on weld pool depression

N DT Abstracts Yan, L. Control of the K-value for radiographic inspection of welded joints 43197 British Journal of Non-Destructive Testing, Vol. 32,...

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N DT Abstracts Yan, L. Control of the K-value for radiographic inspection of welded joints 43197

British Journal of Non-Destructive Testing, Vol. 32, No. 2, pp. 63-68 (Feb. 1990) The significance of controlling the penetrated thickness ratio, K and the maximum thickness ratio K in the radiographic inspection of welding joints is discussed. Taking typical radiographic applications as examples, the paper presents methods for controlling values of K and K as well as practical applications. These methods have been incorporated in the new Chinese National Standard GB- 3323-87.

Lo Vavlo, E.; Masnata, A. Automatic detection of weld defects in radioscopy

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Proceedings of the International Conference on Monitoring, Surveillance and Predictive Maintenance of Plants and Structures, Taormina - Giardini Naxos, Sicily (Italy), 15-18 Oct. 1989, pp. 584-590. Italian Society for Nondestructive Testing An automatic system of defects detection by radioscopic weld images is described. The system consists in real-time radioscopy and in a digital image processor. The detection of the defects is obtained using a segmentation algorithm which operates on the bead image opportunely filtered so that the reinforcement effect and the different focus-film distance can be eliminated. The control procedure operates in two different phases: in the first one, of learning, the sensibility thresholds are determined using penetrometers; in the next phase, in process, the defect is detected by those pixels which show a gray level high than the previously calculated thresholds. A comparison between a visual and automatic evaluation shows the efficiency of the method.

Guu, A.C.; Rokhlin, S.I. Computerized radiographic weld penetration control with feedback on weld pool depression

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Materials Evaluation, Vol. 47, No. 10, pp. 1204-1210 (Oct. 1989) Welding pool depression depends on plasma pressure and heat input to the pool and therefore is related to weld penetration. On the basis of information on pool depression received from radiographic images in real time during welding, the possibility of using automated weld penetration control to maintain the required weld penetration has been studied. The experimental system developed includes an arc welding unit, a welding manipulator, a real-time x-ray system, an image processing unit, and a system controller. By analyzing the radiographic information together with metallographs of the appropriate weld cross section, the depth of the liquid metal in the pool has been determined at different levels of current and weld penetration. During weld control, by comparing the measured depressed pool depth and width with threshold levels, welding conditions are automatically adjusted to maintain the full weld penetration. Monitoring of the depressed pool surface is also important for understanding the dynamics and geometry of the weld pool and it provides a means to study the transition from partial to full weld penetration.

Cabe, D. Radiography of main steam piping welds enclosed within guard pipe 42665

Materials Evaluation, Vol. 47, No. 10, pp. 1126-1128 (Oct. 1989) A radiographic technique is described which is used for in-service inspection of welds in the main steam loops and associated guard pipes of nuclear power stations. Access to the welds is limited; so techniques involving "J-tube"'s are used to position the iridium 192 source. Interval location markers, penetrameters, film cassettes and backing lead are all positioned around the weld through two handholes located 180 degrees apart. (U.K.)

Builtjes, J.H.; Rose, P.; Daum, W. Automatic evaluation of weld radiographs by digital image processing

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X-ray Real-Time Radiography and Image Processing, proceedings of a Symposium, Newbury, Berkshire, Nov. 1988, pp. 63-72. Edited by R. Halmshaw. British Institute of Nondestructive Testing (1989) Real-time image analysis in X-ray inspection of welds is a complex field of pattern recognition. The aim of computerized inspection is the automatic flaw classification. In this article each step of image processing necessary for this purpose is described and discussed. By means of X-ray images of welds it is demonstrated how the real-time evaluation can be realized successfully.

Link. R.; Nuding, W.; Wiacker, H.; Busse, H.P. Weld inspection using real-time radiography 42240

International Advances in Nondestructive Testing, Vol. 14, pp. 143-173 (1989)

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Real-time radiography has become a very useful technique for nondestructive inspection of welds. This paper describes the technique, discusses the features available with real-time systems, including image processing and automatic defect evaluation, and makes a comparison of this technique to standard film radiography.

Link, R.; Nuding, W.; Wiacker, H.; Busse, H.P. Weld inspection using real-time radiography

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International Advances in Nondestructive Testing. Edited by Warren J. McGonnagle. Vol. 14, pp. 143-173, Gordon and Breach Science Publishers(1989) Real-time radiography has become a very useful technique for nondestructive inspection of welds. This paper describes the technique, discusses the features available with real-time systems, including image processing and automatic defect evaluation, and makes a comparison of this technique to standard film radiography.

Anon X-ray real.time imaging (radioscopy) for weld inspection 4th

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progress report Welding in the World, Vol. 27, Nos. 3/4, pp. 68,70,72,74,76 (1989) Four broad conclusions are reiterated for x-ray realtime imaging used for weld inspection, namely that IQI (image quality indicator) sensitivities are as good as those for film radiography. Only projective magnification and digital image processing together offer flaw sensitivity on a par with that attained on film. Digital image processing will consist of image flattening, contrast enhancement and frame integration. Finally image unsharpness measurements should be made separately from IQl sensitivity. The Working Group's experimental work is reviewed and applications of the technique are presented, such as airport baggage handling and the inspection of fusion butt joints in plastic pipes. A universal real-time radiographic system cannot be devised because pattern recognition is so complicated. Hardware and software design must be adapted to the specific inspection problem.

Rokhlin, S.l.; Cho, K.; Guu, A.C. Closed-loop process control of weld penetration using real-time radiography 41678

Materials Evaluation, Vol. 47, No. 3, pp. 363-369 (Mar. 1989) In this study, real-time radiography is used for in-process control of arc welding. The advantages of this technique are on-line response to defect formation in the weld and the application of this information to welding process control. The experimental system developed includes the arc welding unit, the welding manipulator, the real-time x-ray imaging unit, and computerized image-processing and control units. In this system, welding current is automatically controlled as a function of defect-feature extraction from computer processing of weld images. The experimental results are demonstrated for the submerged arc welding process. In this process, the welding pool is covered by a thick layer of the weldingflux and thereforeis optically unobservable. The depth of the welding pool, which characterizes the weld penetration, is a very important characteristic of the weld quality. This characteristic is measured in real time and used for weld tracking and process control. Closed-loop intelligent process control has been demonstrated.

Gusev, E~4.; Firstov, V.G. Quality control of welded joints by high-current pulsed X-ray apparatus 41446

Soviet Journal of Nondestructive Testing, Vol. 24, No. 6, pp. 376-378 (Feb. 1989) The article shows that quality control of welded joints is possible with the aid of high current pulsed x-ray apparatus which uses single pulses. It presents the basic quantitative characteristics of radiographic control that make it possible to determine the focal length, the course of sensitivity, and the optical density of the image. It analyzes the features of the formation of an electroradiographic image using single pulses in the nanosecond range. The prospects of using high-current pulsed x-ray apparatus (PXA) in the regime of single pulses in industry are evaluated.

Rokhlin, SJ.; Guu, A.C. Control of submerged arc weld penetration by radiographic means 41280

NDT International, Vol. 22, No. 2, pp. 74-80 (Apr. 1989) The application of real-time radiography for in-process weld quality evaluation is discussed. The advantages of this technique are on-line testing of weld penetration and the possibility of using this information for welding current control. The experimental system developed includes the arc welding unit, the welding manipulator, the real-time X-ray machine and the videorecording and computerized image processing units. In this system welding current can he remotely controlled during weld observation. The