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Detection and repair of a crack in a BWR feed water nozzle safe end weld
N DT Abstracts ISG2ANb microalloy steel 30 mm thick. Metallographic examination showed that the hardnessof the heat affected zone is 460 HV and certain areas contain a martensitic microstructure.The effect of possibleundetected defects on the service characteristics of containers was determined after removing cracks. Crack opening displacementtestswere carried out on butt welded joints and critical values of theta were determined for the parent metal, weld metal and heat affected zon$. The parameters of permissible defects in these areas were calculated and the dimensions of surface plane and internal defectsdetermined.The crack growth rate during cyclic loading of the container is calculated.
48588 Luk’yanov, V.F.; Naprasnikov, V.V. Predicting the risk of failure of welded joints with an hllowance made for design and technological factors Technical Diagnostics and Nondestructive Testing, Vol. 3, No. 3, pp. 198-202 (1991) The authors describe a model and method of calculating the risk of failure of welded joints on a probability basis. The criterion is represented by a risk function which dependson the defect size. In calculating the risk function, the systemtakes into accountthe effect of various parameterssuch as the loading level, the random variation of the characteristicsof cyclic and static cracking resistanceof the material, the scatter of defect dimensions, the frequency of appearance of defects, and the probability relationships governing the detection of defects in inspection. As an example, an evaluation is made of the risk of failure of a circumferential weld in a shell of power equipment using ultrasonic inspection. It is shown that in single inspection, the maximum of the function of the risk of failure does not exceed 10.
48583
Thaker, R.H.
Significance of defects in NDT of weld-joints Proceedings of Seminar on Non-destructive Testing & Inspection, Vandodara (India), 15-16 Sep. 1990. 15pp. Gramya Research Analysis Institute (1990). The various type of defectsfound in weld joints are listed and discussed. The significance of each type is related back to quality control procedures, and its possible origins considered. Types of defects identified include those involving inadequate bonding, foreign inclusions, geometric defects and cracks. The requirements of the final product determine whether the different types of defect are significant in any structure,and thus whether a weld being inspectedshould be acceptedor rejected. 48335
Lussen, T.
Markov modelling of the fatigue damage in welded structures under in- service inspection International Journal of Fatigue, Vol. 13, No. 5, pp. 417-422 (Sep. 1991) This paper describes a probabilistic cumulative fatigue damage model basedon a simple Markov chain approach.The objective is to develop a tool for a reliability assessmentand a strategy for periodic inspectionof welded joints in marine steel structures. 48053
Pers-Anderson, E.-B.
Detection and repair of a crack in a BWR feed water nozzle safe end weld Proceedings of the 10th lntemational Conference on NDE in the Nuclear and Pressure Vessel Industries, Glasgow (Scotland), 1l-14 Jun. 1990. pp. 271-275. Edited by M.J. Whittle, J.E. Doherty and K. Iida. ASM International, (1990) This article describes how eddy current techniques have been used to complement standard ultrasonic tests in detecting near surface defects in nuclear reactor feed water nozzles. The development of the dual test cam in response to the need to repair a crack in a feed water nozzle in a Swedish
Boiling Water Reactor which was located in a very inaccessible place. Because the repair was performed from outside the vessel, shut-down activities like refueling could be carried out without delay. 47858
Chahurkin, V.F.
47776
Kaswasaki Jt&ogyo KK
Automatic weld defect image data extraction from radiographic film images of pipe welds utilising computer data base based on inspector experience European Patent No. 437,280 (17 Jul. 1991) 47664
Bo, W.; Xiao-jun, L.
Three-dimensions flaw detection for the welded seams of pressure vessels International Journal of Pressure Vessels and Piping, Vol. 48, NO. 3, pp. 331-341 (1991) This article deals with the three-dimensional analysis of internal flaws occurring in the welded seamsof pressurevesselsso as to determine the real location of the defects. For this purposestereoscopictwin radiographswere used.Owing to the fact that radiographsare taken with films in circular form whereasthe films have to be assessedin the flat condition, it is necessaryto establishthe relevant analytic relation between circular and the flat film. TO this end some equations were first established for the image points of the assumed flat film and that of the circular film, leading to the relevant formulae for ascertaining the spa& point location of the defect in the welded seam. Defects of different locations bring about different photocouple-points.The real location of the defect can be determined through its coordinates,Zsub A/ and Y obtained through film observation and calculation. 47561
Morgan, D.W.
Welding problems for nondestructive evaluation Welding Journal, Vol. 70, No. 8, pp. 30-35 (Aug. 1991) This article examines some of the problems associated with welding engineeringand how nondestructiveevaluation can be used to examine most if not all the faults commonly found, especially when several inspection methods are combined. Where there are no material discontinuities, the potential for failure exists but it cannot be effectively tested for using nondestructive techniques. Common problems arising from welding are identified and methodsof inspectiondiscussed. 47450
Austin, KJ.
Successful weld inspection with eddy current Petroleum Industry Inspection Technology, Houston, Texas (United States), 20-22 Jun. 1989. pp. 78-8 1. ASNT (1989) Successful weld inspection for surface breaking defects using eddy current methods is dependent upon the proper selection of instrument, frequency, phaseadjustment,probe style, and probe manipulation. Once the above listed conditions have been met an unambiguousdefect and normal signal can be establishedfor the weld being inspected. Even with a clearly established normal and defect signal, operator experience, interpretation, and documentationplay an important part in a successfulinspection. 46929
Nockemann, C.; Heidt, H.; Thomsen, N.
ROC study of inspection performance in radiographic testing of welded joints Welding in the World, Vol. 29, No. 5-6, pp. 108-l I8 (1991) The complexity of modem NDT equipment as well as the demand for high reliability in several industriesmakes it necessaryto have a tool which can rapidly assesdifferent NDT techniques and devices. For cost benefit considerationsa measure of accuracy has to include not only the amount of correctly detected defects but also the corresponding amount of false indications. In order to satisfy a variety of safety demands this ratio of true and false indications must be known for a wide range of the decision criteria; the signal or defect size which is counted as a real signal; all values smaller are counted as noise. All this information will be provided by only
one receiver operating characteristic(ROC) study of inspection data using the rating- confidence method. An expanded ROC version also yields an assessmentof the accuracyof the defect classificationand of the correctness of the indicated defect importance.
Golovinskii, A.G.; Kiselev, A.V.; Kotkis, A.M.; Khokhlov, 46801 N.F.; Shiryaev, A.M.
The effect of flaws on serviceability of oil and gas pipeline welds Proceedings of the 10th International Offshore Mechanics and Arctic Engineering Conference, Stavanger (Norway), 23 - 28 Jun. 1991, Vol. 2, Safety and Reliability, pp. 77-84. The American Society of Mechanical Engineers ( 199 1) The paper discussesindividual and common effect of planar (cracks, lack-of-penetration) and blunt (pores, slags, etc) flaws on serviceability of pipeline welds. Kinetics of flaw growth is considered. Theoretical and experimental relationships between the strength of thin-walled pipeline welds and magnitudes of lack-of- penetration and hi-low are presented. Alternative acceptance standards based on fitness-for-service criteria are proposed for welds with these flaws.
1
Special features of acoustic emission from fatigue cracks in welded joints in oil pipes Soviet Journal of Nondestructive Testing, Vol. 26, No. 8, pp. 540-544 (Apr. 1991) The count rate, activity, and amplitude of acoustic emission signals in low-cycle tests on pipes for oil pipelines were measured.The fractographic and kinetic special featuresof propagationof fatigue cracks in welded joints in the pipes were examined. The differences between the acoustic emission in full-size componentsof pipelines and other specimenswere determined. Featureswhich can be used to divide the low-cycle fatigue of welded joints in pipes into three stageswere determined.
48588 Luk’yanov, V.F.; Naprasnikov, V.V. Predicting the risk of failure of welded joints with an hllowance made for design and technological factors Technical Diagnostics and Nondestructive Testing, Vol. 3, No. 3, pp. 198-202 (1991) The authors describe a model and method of calculating the risk of failure of welded joints on a probability basis. The criterion is represented by a risk function which dependson the defect size. In calculating the risk function, the systemtakes into accountthe effect of various parameterssuch as the loading level, the random variation of the characteristicsof cyclic and static cracking resistanceof the material, the scatter of defect dimensions, the frequency of appearance of defects, and the probability relationships governing the detection of defects in inspection. As an example, an evaluation is made of the risk of failure of a circumferential weld in a shell of power equipment using ultrasonic inspection. It is shown that in single inspection, the maximum of the function of the risk of failure does not exceed 10.
48583
Thaker, R.H.
Significance of defects in NDT of weld-joints Proceedings of Seminar on Non-destructive Testing & Inspection, Vandodara (India), 15-16 Sep. 1990. 15pp. Gramya Research Analysis Institute (1990). The various type of defectsfound in weld joints are listed and discussed. The significance of each type is related back to quality control procedures, and its possible origins considered. Types of defects identified include those involving inadequate bonding, foreign inclusions, geometric defects and cracks. The requirements of the final product determine whether the different types of defect are significant in any structure,and thus whether a weld being inspectedshould be acceptedor rejected. 48335
Lussen, T.
Markov modelling of the fatigue damage in welded structures under in- service inspection International Journal of Fatigue, Vol. 13, No. 5, pp. 417-422 (Sep. 1991) This paper describes a probabilistic cumulative fatigue damage model basedon a simple Markov chain approach.The objective is to develop a tool for a reliability assessmentand a strategy for periodic inspectionof welded joints in marine steel structures. 48053
Pers-Anderson, E.-B.
Detection and repair of a crack in a BWR feed water nozzle safe end weld Proceedings of the 10th lntemational Conference on NDE in the Nuclear and Pressure Vessel Industries, Glasgow (Scotland), 1l-14 Jun. 1990. pp. 271-275. Edited by M.J. Whittle, J.E. Doherty and K. Iida. ASM International, (1990) This article describes how eddy current techniques have been used to complement standard ultrasonic tests in detecting near surface defects in nuclear reactor feed water nozzles. The development of the dual test cam in response to the need to repair a crack in a feed water nozzle in a Swedish
Boiling Water Reactor which was located in a very inaccessible place. Because the repair was performed from outside the vessel, shut-down activities like refueling could be carried out without delay. 47858
Chahurkin, V.F.
47776
Kaswasaki Jt&ogyo KK
Automatic weld defect image data extraction from radiographic film images of pipe welds utilising computer data base based on inspector experience European Patent No. 437,280 (17 Jul. 1991) 47664
Bo, W.; Xiao-jun, L.
Three-dimensions flaw detection for the welded seams of pressure vessels International Journal of Pressure Vessels and Piping, Vol. 48, NO. 3, pp. 331-341 (1991) This article deals with the three-dimensional analysis of internal flaws occurring in the welded seamsof pressurevesselsso as to determine the real location of the defects. For this purposestereoscopictwin radiographswere used.Owing to the fact that radiographsare taken with films in circular form whereasthe films have to be assessedin the flat condition, it is necessaryto establishthe relevant analytic relation between circular and the flat film. TO this end some equations were first established for the image points of the assumed flat film and that of the circular film, leading to the relevant formulae for ascertaining the spa& point location of the defect in the welded seam. Defects of different locations bring about different photocouple-points.The real location of the defect can be determined through its coordinates,Zsub A/ and Y obtained through film observation and calculation. 47561
Morgan, D.W.
Welding problems for nondestructive evaluation Welding Journal, Vol. 70, No. 8, pp. 30-35 (Aug. 1991) This article examines some of the problems associated with welding engineeringand how nondestructiveevaluation can be used to examine most if not all the faults commonly found, especially when several inspection methods are combined. Where there are no material discontinuities, the potential for failure exists but it cannot be effectively tested for using nondestructive techniques. Common problems arising from welding are identified and methodsof inspectiondiscussed. 47450
Austin, KJ.
Successful weld inspection with eddy current Petroleum Industry Inspection Technology, Houston, Texas (United States), 20-22 Jun. 1989. pp. 78-8 1. ASNT (1989) Successful weld inspection for surface breaking defects using eddy current methods is dependent upon the proper selection of instrument, frequency, phaseadjustment,probe style, and probe manipulation. Once the above listed conditions have been met an unambiguousdefect and normal signal can be establishedfor the weld being inspected. Even with a clearly established normal and defect signal, operator experience, interpretation, and documentationplay an important part in a successfulinspection. 46929
Nockemann, C.; Heidt, H.; Thomsen, N.
ROC study of inspection performance in radiographic testing of welded joints Welding in the World, Vol. 29, No. 5-6, pp. 108-l I8 (1991) The complexity of modem NDT equipment as well as the demand for high reliability in several industriesmakes it necessaryto have a tool which can rapidly assesdifferent NDT techniques and devices. For cost benefit considerationsa measure of accuracy has to include not only the amount of correctly detected defects but also the corresponding amount of false indications. In order to satisfy a variety of safety demands this ratio of true and false indications must be known for a wide range of the decision criteria; the signal or defect size which is counted as a real signal; all values smaller are counted as noise. All this information will be provided by only
one receiver operating characteristic(ROC) study of inspection data using the rating- confidence method. An expanded ROC version also yields an assessmentof the accuracyof the defect classificationand of the correctness of the indicated defect importance.
Golovinskii, A.G.; Kiselev, A.V.; Kotkis, A.M.; Khokhlov, 46801 N.F.; Shiryaev, A.M.
The effect of flaws on serviceability of oil and gas pipeline welds Proceedings of the 10th International Offshore Mechanics and Arctic Engineering Conference, Stavanger (Norway), 23 - 28 Jun. 1991, Vol. 2, Safety and Reliability, pp. 77-84. The American Society of Mechanical Engineers ( 199 1) The paper discussesindividual and common effect of planar (cracks, lack-of-penetration) and blunt (pores, slags, etc) flaws on serviceability of pipeline welds. Kinetics of flaw growth is considered. Theoretical and experimental relationships between the strength of thin-walled pipeline welds and magnitudes of lack-of- penetration and hi-low are presented. Alternative acceptance standards based on fitness-for-service criteria are proposed for welds with these flaws.
1
Special features of acoustic emission from fatigue cracks in welded joints in oil pipes Soviet Journal of Nondestructive Testing, Vol. 26, No. 8, pp. 540-544 (Apr. 1991) The count rate, activity, and amplitude of acoustic emission signals in low-cycle tests on pipes for oil pipelines were measured.The fractographic and kinetic special featuresof propagationof fatigue cracks in welded joints in the pipes were examined. The differences between the acoustic emission in full-size componentsof pipelines and other specimenswere determined. Featureswhich can be used to divide the low-cycle fatigue of welded joints in pipes into three stageswere determined.