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Control of submerged are weld penetration by radiographic means
An automatic system of defects detection by radioscopic wcld imhgcs is described. The system consists in real-time radioscopy and in a digital imagc processor. The detection of thc defects is obtained using a segmentation algorithm which operates on the bead image opportuncly filtcrcd so that the reinforcement effect and the different focus-film distance can bc climinatcd. The control procedure operates in two different phases: in the first one, of learning. the sensibility thresholds are determined using pcnetrometcrs: 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 bctwccn a visual and automatic evaluation shows the cfficiency of the method.
Guu, A.C.; Rokhlin, S.1. Computerized radiographic weld penetration control with feedback on weld pool depression 42669
M a t e r i a l s E v a l u a t i o n , Vol. 47, No. 10, pp. 1204-1210 (Oct. 1989) Welding pool depression depends on plasma pressure and hcat 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 Icvcls 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 fl)r understanding the dynamics and geometry of the weld pool and it provides a means to study the transition from partial to full weld penetration.
Halmshaw, R. X-ray real-time radiography - an introduction
42255
X - r a y R e a l - T i m e R a d i o g r a p h y a n d I m a g e Processing, p r o c e e d i n g s of a S y m p o s i u m , N e w h u r y , B e r k s h i r e , Nov. 1988, pp. 7-17. E d i t e d by R. H a l m s h a w . British I n s t i t u t e of N o n d e s t r u c t i v e T e s t i n g (1989) The various forms of X-ray television-fluoroscopic equipments (real- time radiography or radioseopy) now available are described, concentrating on newer systems using image digitisation and digital image processing. Attempts to obtain high quality images suitable for butt-weld inspection, to be comparable with the image qualities required in film radiography of welds are discussed. Using a conventional wire-type image quality indicator, the IQI wire sensitivity attained can be closely similar to that required for normal-technique weld inspection, but it is argued that because of the larger unsharpness of most RTR images compared with film, this is an inadequate method of assessing image quality. It is suggested that additional measurements are needed, particularly of image unsharpness and image noise.
Builtjes, J.H. ; Rose, P.; Daum, W. Automatic evaluation of weld radiographs by digital image processing 42252
X - r a y R e a l - T i m e R a d i o g r a p h y and I m a g e Processing, p r o c e e d i n g s of a S y m p o s i u m , N e w b u r y , B e r k s h i r e , Nov. 1988, pp. 63-72. E d i t e d by R. H a l m s h a w . British I n s t i t u t e of N o n d e s t r u c t i v e T e s t i n g (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 cvaluation can be realized successfully.
Link. R.; Nuding, W.; Wiacker, H.; Busse, H.P. Weld inspection using real-time radiography
42240
I n t e r n a t i o n a l A d v a n c e s in N o n d e s t r u c t i v e 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.
Jalil. A.; Molla, M.A.R. An overexposure in industrial radiography using an 192Ir radionuclide 42054
H e a l t h Physics, Vol. 57, No. 1, pp. 117-119 (Jul. 1989) An industrial radiographer was accidentally exposed to a high dose of ionizing radiation from an 19Zlr source during radiography of weldjoints in gas pipelines. Some symptoms of high radiation exposure occurred immediately after the incident. The clinical effect of skin erythema developed within 7 d. leading to progressive tissue deterioration. The dose to the body was estimated to be about 2-3 Gy, and the dose to the fingertips was approximately 24 Gy.
Fletcher, M.J.; Speake, J.H. Trends in automated non-destructive testing 41962
W e l d i n g and M e t a l F a b r i c a t i o m Vol. 57, No. 6, pp. 239,240,242 (Jul. 1989) This article gives a brief overview of recent developments in automatic on-line nondestructive testing appropriate to the production of welded components. Real-time radiography in conjunction with digital image processing offers fast, high quality results. Surface particle inspection, used successfully in the automotive industry, offers good reliability especially when combined with
21 6
liquid penetrant tests. Ultrasonic mspeclion is used to detet'l internal dclecls where access is too difficult lor radiography. Eddy current inspection is used successfully in examining offshore welded lerritic structure. 41817 Anon X-ray real-time imaging (radioseopyl flw weld inspection 4th progress
report W e l d i n g in the World, Vol. 27, Nos. 3/4, pp. 68,71),72,74,76 (1989) Four broad conclusions are reiterated Ior x-ray realtimc imaging used lor weld inspection, namely that IOl (image quality indicator) sensitivities arc as good as those for fihn radiography. Only projective magnificalion and digital image processing together offer flaw sensitivity on a par ,,~ith that attained on fflm~ Digital image processing will consist of image flattening, contrast enhancement and frame integration. Finally image unsharpness measurements should be made separately from IQI 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 bull joints in plastic pipes. A universal rcal-flme radiographic system cannot bc devised because pattern recognition is so complicated. Ilardwarc and software design must be adapted to the specific inspection problem. 41580 Ferli, P.; Petter,sen, B. The lack of reliability in nondestructive testing. (In French) Q u a l i t e . R e v u e Pratique de C o n t r o l e I n d u s t r i e l , Vol. 28, 156 his, pp. 44-52 (1989) The most recent results hom NDT performance studies in progress in the Nordic countries arc presented, together with some implications for current NDT practice. The performance studies so far carried out have dealt with the radiographic and ultrasonic examination of weld specimens containing 730 flaws. A total of 4600 ultrasonic and 3401) radiographic observations was made on these flaws. The results arc data on the probability of detection by the two techniques, as function of their sensitivity and of flaw size for the different types of flaw. For ultrasonics an analysis has also been made of the scatter of echo heights, the ability to identify typical defects and the variability of NDT operatives. The NDT performance data obtained and the uncertainties observed will have an impact on NDT practice and some examples of their practical application are given. These examples range from naditional quality control to fitness for purpose. Performance studies of the magnetoscopic and liquid penctrant methods arc also in progress, and their present status is rcpmled.
Hopwood. 7". Long-term evaluation of the acoustic emission weld monitor
41533
Kentucky Transportation Research Program, Lexington, (United States), P B 8 9 - 1 2 2 6 4 2 / G A R , pp. 165 (Feb. 1988) The Kentucky Transportation Research Program conducted an extended 10month evaluation of the Acoustic emission weld monitor (AEWM) in a bridge fabrication shop. That device was used to detect welding flaws during typical production of butt-welds on flanges and webs used in steel bridges. A total of 153 welds were monitored. AEWM test results were compared with visual inspection and double-blind results of conventional nondestructive testing routinely conducted on the welds, The AEWM did not miss any flaws detected visually or by nondestructive testing. Three AEWM flaw indications were confirmed by conventional nondestructive testing (radiography). The AEWM has shown the sensitivity to detect AWS code-rejcctable defects. Due to the success of the unit in detecting flaws, further development is warranted.
Gusev, E.A.; Firstov, V.G. Quality control of welded joints by high-current pulsed X-ray apparatus 41446
Soviet J o u r n a l of N o n d e s t r u c t i v e Testing, Vol. 24, No. 6, pp. 376-378 (Feb. 1989) The article shows thai 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 elcctroradiographic 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 arc evaluated 41281) Rokhlin, S.I.; Guu, A.C. Control of submerged arc weld penetration by radiographic means N D T I n t e r n a t i o n a l , Vol. 22, No. 2, pp. 74-80 ( A p r . 1989) " The application of real-time radiography for in-process weld quality evaluation is discussed. The advantages of this technique arc on-line testing of weld penetration and the possibility of using this information for wclding current control. The cxperimental system developed includes the arc welding unit, the welding manipulator, the real-time X-ray machine and thc videorecording and computerized image processing units. In this system wclding current can be rcmotely controllcd during weld observation. The. experimental results arc dcmonstratcd for thc submerged arc welding process. In this process thc wclding pool is covered by a thick layer of welding flux and is thcrcforc optically invisible. By using computer data on thc 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 framcs pcr sccond. The depth of the welding pool which characterizcs the weld penetration is a very important characteristic of the weld quality. This characteristic can be measured in real timc and used for weld tracking and welding current control.
N DT & E International August 1 991
Guu, A.C.; Rokhlin, S.1. Computerized radiographic weld penetration control with feedback on weld pool depression 42669
M a t e r i a l s E v a l u a t i o n , Vol. 47, No. 10, pp. 1204-1210 (Oct. 1989) Welding pool depression depends on plasma pressure and hcat 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 Icvcls 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 fl)r understanding the dynamics and geometry of the weld pool and it provides a means to study the transition from partial to full weld penetration.
Halmshaw, R. X-ray real-time radiography - an introduction
42255
X - r a y R e a l - T i m e R a d i o g r a p h y a n d I m a g e Processing, p r o c e e d i n g s of a S y m p o s i u m , N e w h u r y , B e r k s h i r e , Nov. 1988, pp. 7-17. E d i t e d by R. H a l m s h a w . British I n s t i t u t e of N o n d e s t r u c t i v e T e s t i n g (1989) The various forms of X-ray television-fluoroscopic equipments (real- time radiography or radioseopy) now available are described, concentrating on newer systems using image digitisation and digital image processing. Attempts to obtain high quality images suitable for butt-weld inspection, to be comparable with the image qualities required in film radiography of welds are discussed. Using a conventional wire-type image quality indicator, the IQI wire sensitivity attained can be closely similar to that required for normal-technique weld inspection, but it is argued that because of the larger unsharpness of most RTR images compared with film, this is an inadequate method of assessing image quality. It is suggested that additional measurements are needed, particularly of image unsharpness and image noise.
Builtjes, J.H. ; Rose, P.; Daum, W. Automatic evaluation of weld radiographs by digital image processing 42252
X - r a y R e a l - T i m e R a d i o g r a p h y and I m a g e Processing, p r o c e e d i n g s of a S y m p o s i u m , N e w b u r y , B e r k s h i r e , Nov. 1988, pp. 63-72. E d i t e d by R. H a l m s h a w . British I n s t i t u t e of N o n d e s t r u c t i v e T e s t i n g (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 cvaluation can be realized successfully.
Link. R.; Nuding, W.; Wiacker, H.; Busse, H.P. Weld inspection using real-time radiography
42240
I n t e r n a t i o n a l A d v a n c e s in N o n d e s t r u c t i v e 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.
Jalil. A.; Molla, M.A.R. An overexposure in industrial radiography using an 192Ir radionuclide 42054
H e a l t h Physics, Vol. 57, No. 1, pp. 117-119 (Jul. 1989) An industrial radiographer was accidentally exposed to a high dose of ionizing radiation from an 19Zlr source during radiography of weldjoints in gas pipelines. Some symptoms of high radiation exposure occurred immediately after the incident. The clinical effect of skin erythema developed within 7 d. leading to progressive tissue deterioration. The dose to the body was estimated to be about 2-3 Gy, and the dose to the fingertips was approximately 24 Gy.
Fletcher, M.J.; Speake, J.H. Trends in automated non-destructive testing 41962
W e l d i n g and M e t a l F a b r i c a t i o m Vol. 57, No. 6, pp. 239,240,242 (Jul. 1989) This article gives a brief overview of recent developments in automatic on-line nondestructive testing appropriate to the production of welded components. Real-time radiography in conjunction with digital image processing offers fast, high quality results. Surface particle inspection, used successfully in the automotive industry, offers good reliability especially when combined with
21 6
liquid penetrant tests. Ultrasonic mspeclion is used to detet'l internal dclecls where access is too difficult lor radiography. Eddy current inspection is used successfully in examining offshore welded lerritic structure. 41817 Anon X-ray real-time imaging (radioseopyl flw weld inspection 4th progress
report W e l d i n g in the World, Vol. 27, Nos. 3/4, pp. 68,71),72,74,76 (1989) Four broad conclusions are reiterated Ior x-ray realtimc imaging used lor weld inspection, namely that IOl (image quality indicator) sensitivities arc as good as those for fihn radiography. Only projective magnificalion and digital image processing together offer flaw sensitivity on a par ,,~ith that attained on fflm~ Digital image processing will consist of image flattening, contrast enhancement and frame integration. Finally image unsharpness measurements should be made separately from IQI 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 bull joints in plastic pipes. A universal rcal-flme radiographic system cannot bc devised because pattern recognition is so complicated. Ilardwarc and software design must be adapted to the specific inspection problem. 41580 Ferli, P.; Petter,sen, B. The lack of reliability in nondestructive testing. (In French) Q u a l i t e . R e v u e Pratique de C o n t r o l e I n d u s t r i e l , Vol. 28, 156 his, pp. 44-52 (1989) The most recent results hom NDT performance studies in progress in the Nordic countries arc presented, together with some implications for current NDT practice. The performance studies so far carried out have dealt with the radiographic and ultrasonic examination of weld specimens containing 730 flaws. A total of 4600 ultrasonic and 3401) radiographic observations was made on these flaws. The results arc data on the probability of detection by the two techniques, as function of their sensitivity and of flaw size for the different types of flaw. For ultrasonics an analysis has also been made of the scatter of echo heights, the ability to identify typical defects and the variability of NDT operatives. The NDT performance data obtained and the uncertainties observed will have an impact on NDT practice and some examples of their practical application are given. These examples range from naditional quality control to fitness for purpose. Performance studies of the magnetoscopic and liquid penctrant methods arc also in progress, and their present status is rcpmled.
Hopwood. 7". Long-term evaluation of the acoustic emission weld monitor
41533
Kentucky Transportation Research Program, Lexington, (United States), P B 8 9 - 1 2 2 6 4 2 / G A R , pp. 165 (Feb. 1988) The Kentucky Transportation Research Program conducted an extended 10month evaluation of the Acoustic emission weld monitor (AEWM) in a bridge fabrication shop. That device was used to detect welding flaws during typical production of butt-welds on flanges and webs used in steel bridges. A total of 153 welds were monitored. AEWM test results were compared with visual inspection and double-blind results of conventional nondestructive testing routinely conducted on the welds, The AEWM did not miss any flaws detected visually or by nondestructive testing. Three AEWM flaw indications were confirmed by conventional nondestructive testing (radiography). The AEWM has shown the sensitivity to detect AWS code-rejcctable defects. Due to the success of the unit in detecting flaws, further development is warranted.
Gusev, E.A.; Firstov, V.G. Quality control of welded joints by high-current pulsed X-ray apparatus 41446
Soviet J o u r n a l of N o n d e s t r u c t i v e Testing, Vol. 24, No. 6, pp. 376-378 (Feb. 1989) The article shows thai 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 elcctroradiographic 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 arc evaluated 41281) Rokhlin, S.I.; Guu, A.C. Control of submerged arc weld penetration by radiographic means N D T I n t e r n a t i o n a l , Vol. 22, No. 2, pp. 74-80 ( A p r . 1989) " The application of real-time radiography for in-process weld quality evaluation is discussed. The advantages of this technique arc on-line testing of weld penetration and the possibility of using this information for wclding current control. The cxperimental system developed includes the arc welding unit, the welding manipulator, the real-time X-ray machine and thc videorecording and computerized image processing units. In this system wclding current can be rcmotely controllcd during weld observation. The. experimental results arc dcmonstratcd for thc submerged arc welding process. In this process thc wclding pool is covered by a thick layer of welding flux and is thcrcforc optically invisible. By using computer data on thc 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 framcs pcr sccond. The depth of the welding pool which characterizcs the weld penetration is a very important characteristic of the weld quality. This characteristic can be measured in real timc and used for weld tracking and welding current control.
N DT & E International August 1 991