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
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
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
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)
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
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
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
N DT Abstracts experimental results are demonstrated for the submerged arc welding process. In this process the welding pool is covered by a thick layer of welding flux and is therefore optically invisible. By using computer data on the grey levels of the weld images and their histogram distributions, the three- dimensional shape of the submerged arc pool can be recognized, image- digitized and analysed in real time at the rate of 30 frames per second. The depth of the welding pool which characterizes the weld penetration is a very important characteristic of the weld quality. This characteristic can he measured in real time and used for weld tracking and welding current control.
Polansky, D.; Criscuolo, E.; Berger, H.; Jones, T.S. Development of graded reference radiographs for aluminum welds. Phase 1 41277
Industrial Quality Inc., Gaithersburg, Maryland (United States) AD-A195 594/7/GAR, 33 pp. (Mar. 1988) The purpose of this project was to develop a data bank for graded sets of reference radiographs of aluminum welds. These are extremely valuable for procurements related to ships, fircraft, other vehicles, construction and similar projects that include aluminum welds, and serve as a recognized way of acceptance or rejection of wehls. A present set of reference radiographs are used for steel welds. During this project, a data bank of production radiographs of aluminum weilds was collected. Several thousand radiographs are presently in the data bank. From this data bank, a set of proposed reference radiographs has been assembled. These include five grades of reference radiographs tor three types of porosity, fine scattered porosity, coarse scattered porosity and linear porosity. The suggested reference radiograph document also includes three grades of clustered porosity, two illustrations of inadequate penetration, two illustrations of tungsten inclusions, and examples of longitudinal and transverse cracks, lack of fusion and undercut.
Spremo, N.; Begovic, B.; Doko, A. Specific aspects of radiographic inspection performed on fillet welds of small diameter pipe nozzles 41063
Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1143-1148. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. High operating parameter vessels, equipped with small diameter pipe nozzles connected to the vessel shell by means of welding procedure are used in thermal power, petrochemical, nuclear and other vital plants. It is necessary to make a 100% range radiographic inspection of such, usually fillet welds of small diameter pipe nozzles. The paper presents experience gained in the selection of radiographic inspection method on fillet welds of pipe nozzles with a 100 mm interrtal diameter and 25 mm wall thickness on vital vessel for nuclear power plarLt.
Berger, H.; Polansky, D.; Criscuolo, E.L. A data bank for graded reference radiographs of aluminum welds 40847
Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands) 23-28 Apr. 1989, Vol. 1, pp. 86-89. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989 A set of graded reference radiographs of aluminum welds has been assembled. The set covers the thickness range from 9.5 to 19mm for aluminum in the 5000 and 6000 series alloys. The set includes five grades for three types of porosity, fine scattered, coarse scattered and linear; three grades of clustered porosity; two illustrations of inadequate penetration and tungsten inclusions and examples of longitudinal and transverse cracks, lack of fusion and undercut. This will serve as an interim set until a more formal graded reference radiograph document becomes available.
Munro, J.J.; McNulty, R.E.; DeSimone, A. An assessment of the detectability of cracks in the radioscopic examination of weldments 40843
Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherhmds) 23-28 Apr. 1989, Vol. 1, pp. 62-67. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989 Real-time radioscopic examination of welds is a rapidly developing technique. Contrast sensitivities better than 2% are often required. Real-time radioscopic equipment is now available which can satisfy the contrast sensitivity requirements for this type of weld inspection. However, there exists a degree of controversy regarding the ability of real-time radioscopic systems to del~ct cracks. A stud)' was conducted to assess the ability of radioscopic systems to detect cracks in a thickness typical of the range of thicknesses encountered in weld radiography.
Eckelt, B.; Meyendorf, N.; Morgner, W.; Richter, U. Use of automatic image processing for monitoring of welding processes and weld inspection
Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands) 23-28 Apr. 1989, Vol. 1, pp. 37-41. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989 Advantageous incorporation of image processing into quality assurance in automatic welding is exemplified by thermography as well as flaw detection by radiography. The problem area of monitoring the temperature regime has been solved, permitting quality assurance of specified mechanical and process properties. Weld flaws are automatically detected and satisfactorily evaluated by means of radiographs. Work is in hand to improve the hardware and flaw classification as a function of the load conditions expected.
Rokhlin, S.I. In-process radiographic evaluation of arc welding 40837
Materials Evaluation, Vol. 47, No. 2, pp. 219-224 (Feb. 1989) Real-time radiography is used for volume observation in the welding pool and the heat-affected zone during the weld process. The advantages of such a technique are on-line testing of defect formation in the weld, the study of metal fusion and filler metal-base metal interaction, and the study of metal transfer in the welding pool. This technique may also he used for postservice real-time remote testing of weld quality. Monitoring of the welding process with real-time radiography opens new opportunities for the study of arc welding physics. As an example, the metal transfer and plasma pressure cycle for submerged arc welding are documented. Another application is to use information on weld quality, received from automatic recognition of real-time radiographic images, in feedback for closed-loop intelligent weld control. This new concept of arc welding process control as distinguished from conventional welding quality is used. An experimental system that implements this concept is discussed.
Mayes, M.J.; Fitting, D.W. Evaluation of a dry.silver system for weld radiography
Materials Evaluation, Vol. 47, No. 2, pp. 225-232 (Feb. 1989) A dry-silver industrial x-ray system is evaluated for use in xradiography of steel weldments. Evaluation is based on comparisons with conventional radiographic film, sensitivity obtained using penetrameters, applicable code requirements, and subjective radiographer impressions. Characteristic curves and technique charts have been constructed and weld radiographs have been made of full- penetration butt weldments in fiat plate. it has been determined that, using 3M Inspex film, resolution required by common welding inspection codes is obtainable for steel weldments up to 1 in. (2.5 cm) in thickness. The product is found to he attractive in regard to cost, convenience, speed, portability, and low maintenance. Best results are obtained if weld cross section is constant (within -t-- I/4 in. [6.4 mini). Proper selection of x-ray tube potential and intensifying screen is required. With proper control of radiographic variables and within certain limitations, the 3M system is a useful supplementary radiographic tool.
Kobayashi,H., Ookubo, K.; Ikeda, Y.; Wakao, H. Detection of weld crackings using neutron radiography technique (In Japanese)
Journal of Japanese Society for Non-Destructive Inspection, Vol. 37, No. 9A, pp. 767-768 (Sep. 1988)
Daum, W.; Heidt, H.; Rose, P.; Builtjes, J.H. Real time evaluation of weld radiographs by digital image processing 40329
Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom) 13-17 Sep. 1987. Vol. 3, pp. 1568-1574. Pergamon Press, 3173 pp. (1988). In this article some basic aspects of the hardware and software adaption for real time image analysis of weld radiographs are discussed and an optimized image analysis strategy is presented.
Rokhlin, S.I.; Guu, A.C.; Applegate, D.E. In-process radiography of arc weld 40133
Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7B, pp. 1581-1588. Edited by D.D.Thompson and D.E. Chimenti, Plenum Press, 1988. This paper summarizes some results for in-process evaluation of weld penetration for submerged arc welding. Submerged arc welding is distinguished from other welding techniques in that the welding pool is covered by a thick layer of special powder which is called 'welding flux'. During welding this flux melts and shields the arc while the molten metals