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Relevant bibliographies by topics / Defects in welding

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Academic literature on the topic 'Defects in welding'

Author: Grafiati

Published: 6 September 2023

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Journal articles on the topic "Defects in welding"

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Liu, Jinxin, and Kexin Li. "Intelligent Metal Welding Defect Detection Model on Improved FAST-PNN." Coatings 12, no. 10 (October 11, 2022): 1523. http://dx.doi.org/10.3390/coatings12101523.

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In order to solve the problem of accurate and efficient detection of welding defects in the process of batch welding of metal parts, an improved Probabilistic Neural Network (PNN) algorithm was proposed to build an automatic identification model of welding defects. Combined with the characteristics of the PNN model, the structure and algorithm flow of the FAST-PNN algorithm model are proposed. Extraction of welding defect image texture features of metal welded parts by a Gray Level Co-occurrence Matrix (GLCM) screens out the characteristic indicators that can effectively characterize welding defects. Weld defect texture features are used as input to build a defect classification model with FAST-PNN, for accurate and efficient classification of welding defects. The results show that the improved FAST-PNN model can effectively identify the types of welding defects such as burn-through, pores and cracks, etc. The classification recognition accuracy and recognition efficiency have been significantly improved. The proposed defect welding identification method can accurately and effectively identify the damage types of welding defects based on a small number of defect sample images. Welding defects can be quickly identified and classified by simply collecting weld images, which helps to solve the problem of intelligent, high-precision, fast real-time online detection of welding defects in modern metal structures; it provides corresponding evidence for formulating response strategies, with a certain theoretical basis and numerical reference.

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Widyawati, Fauzi, and Lino Marano. "IDENTIFIKASI CACAT LASAN FCAW PADA FONDASI MESIN KAPAL MENGGUNAKAN METODE ULTRASONIC TESTING." Jurnal TAMBORA 5, no. 2 (July 21, 2021): 53–58. http://dx.doi.org/10.36761/jt.v5i2.1124.

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Ultrasonic testing is one of the non-destructive inspection methods for welding results. The ultrasonic testing method has several advantages, namely it can be used to analyze the position of the defect in the object, both the depth of the defect and the dimensions of the defect, and it is an environmentally friendly method. Physical defects that are in solid objects of course cannot be known from direct vision so it is necessary to carry out an inspection of an object to see whether or not there are defects that occur in solid objects. Ultrasonic testing of the results of FCAW welding on the foundation of the ship's engine. FCAW welding is applied to the foundation with two types of welding positions, namely the overhead position coded P1 and the horizontal position coded P2. The test was carried out using a wave frequency of 4 MHz and using a 0° probe for analysis of defects in the area around the weld metal and a 70° probe for analysis of the weld metal. The tests were carried out using the ASME section V and ASTM E164 standards as the standard for determining defects. The test results at the P1 welding position found two types of defects, namely incomplete fusion defects with five welding points with the longest defect length of 40mm and porosity defects with two points with the longest defect length of 30mm. While the results of ultrasonic testing at the P2 welding position found two types of defects, namely slag inclusion defects with a defect length of 35mm and incomplete penetration defects with a defect length of 20 mm. The conclusion of ultrasonic testing is that the difference in welding positions is that the welding position greatly affects the quality of the welding results. The defects resulting from the welding position also vary.

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Zai, Le, and Xin Tong. "FusionWelding of High-Strength Low-Alloy Steel: A Mini- Review." SOJ Materials Science & Engineering 7, no. 1 (March 26, 2019): 1–4. http://dx.doi.org/10.15226/sojmse.2019.00157.

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High-Strength Low-Alloy (HSLA) steel exhibits excellent tensile strength and ductility, and it also possesses good welding performance due to its low carbon equivalent. However, welding defects always inevitably appear during the fusion weldingof HSLA steel. In this paper, the previous investigations on the microstructure of the joined HSLA steel by different fusion welding processes arereviewed, and the mechanical properties of the fabricated joint are analyzed. Also, the practicability of different fusion welding processes on HSLA steel has been systematically analyzed. Finally, the prospect of the welding of HSLA steel is expected according to the research status. Keywords: High-Strength Low-Alloy Steel; Fusion Welding; Welding Defect; Microstructure; Mechanical Properties

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Rizvi, Saadat Ali, and Wajahat Alib. "Welding defects, Causes and their Remedies: A Review." Teknomekanik 2, no. 2 (December 15, 2019): 39–47. http://dx.doi.org/10.24036/tm.v2i2.3272.

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This review paper looks at the causes of welding defects and their remedies which occur during the welding process. Welding industries in developing countries bearing poor quality and productivity due to the involvement of a number of the process parameter. Even in a completely controlled process, defects in the welding are observed and hence welding process is also known as the process of uncertainty which challenges explanation about the cause of welding defects. In order to identify the welding defect and problem-related to welding, the study is aimed at the research work. This will be beneficial in enhancing the yield of welding. Beside this, standardization (optimization) of process parameter for the entire cycle of manufacturing of the critical part is intended in the proposed work .This review paper also provides the accurate guideline to the quality control department to find welding defects and will help them to analyze defects which are not desired. In this review paper, an attempt has been made to categorise the various welding defects and their root causes of happening.

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Et.al, Christopher Paulraj. "An intelligent Model for Defect Prediction in Spot Welding." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 3 (April 11, 2021): 3991–4002. http://dx.doi.org/10.17762/turcomat.v12i3.1689.

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There are more than 30% defect in the spot welding of cars and randomly chosen cars are performed ultrasound or destructive testing. This makes the process very vulnerable and unpredictable. This results in huge reworks, productivity, monetary loss and negative impact on brand name. This research paper presents the prediction of defect using machine learning models and as well forecasting models in spot welding through optimized methodology. This defect prediction model is useful in determining the defects that are likely to occur during spot welding. The forecasting model for process parameters data pattern, trends, etc. helps to identify the link between predicted defects. This model can evolve and improve over time by considering data from previous phases and history data of the spot welding cycle. Predicting the defects before testing begins improves the quality of the product being delivered and helps in planning and decision making for future spot welding. The optimized defect prediction methodology in spot welding reduces the defects and predicted sample for testing which reduces the rework and increase the productivity, monetary value and brand name. The experimental result shows that the spot-welding methodology has shown improvement over existing spot-welding method. Please see the six-sigma (Fig:13) chart for before and after improvement curve and value.

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Li, Qiang, Qi Lu, Yingchun Chen, Junwei Su, and Jie Yang. "Effect of the ultrasonic phased array on defect detection of HDPE electro-fusion joint." Journal of Physics: Conference Series 2419, no. 1 (January 1, 2023): 012070. http://dx.doi.org/10.1088/1742-6596/2419/1/012070.

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Abstract As a common welding method for polyethylene natural gas pipelines, electro-fusion welding has been widely used. However, defects are easy to occur in the fusion area during the welding. In this paper, high-density polyethylene (HDPE) pipes with different types of electric welding joint defects are processed, and the detection effect of the ultrasonic phased array on joint defects is explored. The results show that: Ultrasonic phased array detection technology is easy to operate and reliable. It can detect three common defects: inadequate socket, cold welding, and scratch of oxide scale. In addition, according to the inspection result chart, the defect type can be accurately judged.

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Zhu, Caixia, Haitao Yuan, and Guohong Ma. "An active visual monitoring method for GMAW weld surface defects based on random forest model." Materials Research Express 9, no. 3 (March 1, 2022): 036503. http://dx.doi.org/10.1088/2053-1591/ac5a38.

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Abstract In the automatic manufacturing of robotic welding, real-time monitoring of weld quality is a difficult problem. Meanwhile, due to volatilization of zinc vapor in galvanized steel and complexity of welding process, the existence of welding defects greatly affects industrial production process. And real-time detection of welding defects is a key step in development of intelligent welding. To realize real-time monitoring of weld surface defects, an active visual monitoring method for weld surface defects is proposed. Firstly, after applying Gabor filter to remove interference signals such as arc and noise, obtain weld centerline image; then employ the slope analysis method to extract peak valley coefficient of weld defects, extract five feature points of weld surface quality by Douglas-Puke algorithm, and analyse geometric and spatial distribution features of different types of defects in weld laser stripe images. Finally, using eight feature vectors extracted from weld features, design a weld defect recognition random forest model based on decision tree. After optimizing the decision tree depth and number of model evaluators, compared with the traditional decision tree ID3 and CART algorithm model, this model has better performance than traditional machine learning algorithms on five weld surface defect data sets. The experimental results show that accuracy of weld defect identification in the training set is 99.26%, accuracy of weld defect recognition in the test set is 96%, and processing time of a single image is only 5.3 ms, which overcomes difficulty of real-time weld defect detection in intelligent welding and ensures real-time and accuracy.

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Hua, Liang, Peng Xue, Jin Ping Tang, Hui Jin, and Qi Zhang. "Welding Defects Classification Based on Multi-Weights Neural Network." Advanced Materials Research 820 (September 2013): 130–33. http://dx.doi.org/10.4028/www.scientific.net/amr.820.130.

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Incomplete fusion and incomplete penetration are two types of damage serious welding defects. These two kinds of defects have the similarity in the features in X-ray imaging. Identifying the two kinds of defects automatically and accurately can improve the welding technology and improve the quality of welding effectively. The causes of defects and features of X-ray images are described in the paper. The welding defects calssification method based on multi-weights neural network is put forward in the paper. The multi-weights neural network based on graphic geometry theory is introduced, which uses the geometrical shape in high dimensional space to cover the same class defect samples via constructing multi-weights neural network. The experimental results proved the effectiveness of the algorithm.

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Song, Seung-Hyon, Chang-Soon Lee, Tae-Hwan Lim, Auezhan Amanov, and In-Sik Cho. "Fatigue Life Improvement of Weld Beads with Overlap Defects Using Ultrasonic Peening." Materials 16, no. 1 (January 3, 2023): 463. http://dx.doi.org/10.3390/ma16010463.

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Welding defects are common during the production of large welded structures. However, few studies have explored methods of compensating for clear welding defects without resorting to re-welding. Here, an ultrasonic peening method to compensate for the deteriorated mechanical properties of overlap weld defects without repair welding was studied. We experimentally investigated changes in the mechanical properties of defective welds before and after ultrasonic peening. The weld specimen with an overlap defect contained a large cavity-type defect inside the weld bead, which significantly reduced the fatigue life. When the surface of the defective test piece was peened, the fatigue life of the weld plate was restored, resulting in an equivalent or higher number of cycles to failure, compared to a specimen with a normal weld. The recovery of mechanical properties was attributed to the effect of surface work hardening by ultrasonic peening and the change in stress distribution. Thus, ultrasonic peening could compensate for the deterioration of mechanical properties such as tensile strength, fatigue life, and elongation due to overlap defects, without resorting to repair welding.

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Junianto, Teguh, Imam Bayhaqi, and Erna Rahayu. "Pengendalian Kualitas Pengelasan Pada Proyek Pipeline Sabar#2." Jurnal Inovator 3, no. 2 (December 21, 2020): 1–8. http://dx.doi.org/10.37338/ji.v3i2.133.

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PT. ICG is a company that handles the pipeline welding process at PetroChina Jabung Ltd. The welding process carried out is cutting, rolling, pressing and painting. The problem that occurs is that 243 defects are found from the output of 457 welding points. The types of defects after the welding process included 106 points of Root Cancellation defects, 99 points of Incomplete fusion, 29 points of Porosity, 8 points of Slug Inclusion, and 1 point of Tungsten Inclusion. This study aims to control quality by looking at the sigma value of the pipeline production process and analyzing the improvements that should be made to reduce the defects that occur. The results of the calculation of Defect Per Million Opportunities (DPMO) show that the number of welding defects that arise every one million opportunities is 174,10. The quality of the welding process in the pipeline Sabar # 2 project is at a sigma value of 2,43 with a DPMO value of 174,10. From the results of the sigma value obtained, this value is still far from the expectations of Petrochina's management to achieve a minimum sigma value of 4,0. The potential causes of weld defects include welding machines, work errors, work methods and work environment.

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Dissertations / Theses on the topic "Defects in welding"

1

Auger, Marc. "Detection of laser-welding defects using neural networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65599.pdf.

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Hunt, Johnathon Bryce. "Defect Detection in Friction Stir Welding by Measureable Signals." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8676.

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Friction stir welding (FSW) is an advantageous solid-state joining process, suitable for many materials in the energy, aerospace, naval and automotive industries. Like all other welding processes, friction stir welding requires non-destructive evaluation (NDE). The time and resources to preform NDE is expensive. To reduce these costs, nontraditional NDE methods are being developed for FSW. Spectral based defect recognition uses the forces during the welding process to validate weld quality. Although spectral NDE methods have shown promise as an alternative NDE processes, many research welding speeds do not correspond to manufacturing speeds, nor do they explain the relationship between the spectral data and the process. The purpose of this work is to explore the possibility of acquiring additional information about the defect. Namely the defect’s type, location, and magnitude. In this study, welds with “wormhole” defects were produced at 2000, 2500 and 3000 mmpm in 5754 aluminum. The welding process forces and torque were measured and analyzed spectrally. The welded plates were then imaged with x-ray photography, a validated NDE method. It was found that low frequencies (0 – 4 Hz) in the y & z force signals correlate with defect presence in high speed FSW. In addition, the strong correlation between the spectral data and the presence of a defect allowed for defect magnitude predictions. Linear fits were applied to the defect measurements and the spectral data. Large error inhibits the wide use of this prediction method.

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Da, Costa S. C. "The prediction of risk of welding defects at the procedure stage using computer knowledge based systems." Thesis, Cranfield University, 1992. http://dspace.lib.cranfield.ac.uk/handle/1826/4446.

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The purpose of this research was to develop a methodology to evaluate the likelihood of defective welds as a procedure proposal is entered into a computerised database system. The approach developed was assessed for hydrogen induced cold cracking (HICC) since this defect is a major problem in welding technology. An expert system was used to implement the methodology. The information for the expert system knowledge base was partly gathered from previous work in this area. The technique necessary to analyze and incorporate knowledge was organized in a structured form including the major area to be attacked. The final system was implemented using an expert system shell. The global task of analyzing a welding procedure was broken-down into three different stages. A welding procedure specification comprised the first stage. In the second stage, an interface between the expert system software and a database was implemented. Having proved the feasibility and advantages of integrating the expert system shell with a relational database the remainder of the work was devoted to the development of a strategy for operating the expert system and in particular dealing with uncertainty. Detailed validation of the knowledge base and the system as a whole were confined to a single defect type in the belief that the modularity of the system would allow extension to other defect types and the strategies developed in the present work should it be applicable. Results have shown that the system performs well in the specified area. Validation trials using simulated welding conditions generated by the expert system have shown a very good correlation with practical results for different classes of steels. The integration between approved welding procedure records and procedure qualification records could be the basis for a complete welding database management. Practical application of this system could be extended for educational purpose and training facilities.

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Dolejský, Tomáš. "Porovnání nákladů na svařování a Virtual Welding." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231042.

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The thesis deals with a potential application of welding simulators in basic courses of welding held in welding schools. The first section briefly describes the welding simulators in the global market. There is a detailed description and the control of the welding simulator Virtual Welding, a description of core courses of welding and the necessary welding technology in the following section. Experiments with a welding simulator are carried out in the last section and also their evaluation, comparison and summary of costs.

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Zareie, Rajani Hamid Reza. "Development of a three-dimensional multi-scale model to study the formation of solidification defects in fusion welding." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57601.

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One of the long-standing challenges in joining of aluminum alloys is the occurrence of solidification defects, i.e. hot cracking and porosity, since these defects significantly increase manufacturing costs. This research project investigates the formation of solidification defects through development of a novel and comprehensive 3-D multi-scale and multi-physics numerical study and then application to the GTA welding of the aluminum alloy AA6061. The developed multi-scale model is composed of four different modules: 1) Solidification, 2) Deformation, 3) Fluid flow, and 4) Defect formation. The solidification module numerically reconstructs the 3-D microstructure of semisolid welds using a granular model of solidification. Specifically, a modified Voronoi tessellation algorithm is used to generate an unstructured grid representing the weld microstructure. The reconstructed microstructure contains both columnar and equiaxed grains and varies as a function of welding process parameters. Then, the Scheil equation is used in combination with the temperature field obtained through the Rosenthal equation and the reconstructed 3D microstructure to simulate solidification. This module outputs the evolving 3D structure of the semisolid weld composed of solid grains and a network of micro liquid channels for use by the deformation and fluid flow modules as the simulation geometry. The deformation module analyzes via finite elements the deformation of the semisolid weld due to externally applied strains and self-induced strains such as thermo-mechanical strains and solidification shrinkage in order to obtain local strain rates within the micro liquid channels. The local strain rates outputted by the deformation module feed a fluid flow analysis module in which the pressure field within the semisolid weld is calculated. Finally, the defect formation module uses various defect formation models to link the pressure field and the local strain rates to the formation of solidification defects including micro cracks and hydrogen porosity.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

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Li, Peigang. "Cold lap formation in Gas Metal Arc Welding of steel : An experimental study of micro-lack of fusion defects." Doctoral thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5596.

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Cold laps are defined as micro-lack of fusion defects at the weld toe more or less parallel to the surface of the parent plate. These defects are known to negatively influence the fatigue properties of weldments. Previous studies suggest that cold lap formation can not be avoided completely in Gas Metal Arc Welding (GMAW). Therefore, a better understanding of formation mechanisms is imperative to be able to minimize the number and size of these defects. The main objective of this work has been to provide a more comprehensive understanding of cold laps, including categorising, characterisation and defining the most significant factors for formation. GMAW was used to produce welds that were investigated by metallographic methods using light optical microscopy, scanning electron microscopy and energy dispersive spectrometry. A novel classification of cold laps was introduced and three types of cold laps were identified: spatter cold laps, overlap cold laps and spatter-overlap cold laps. It was shown that cold laps are partially or fully filled by oxides. The most common oxides are manganese silicon oxides which were concluded to be formed primarily by oxidation of droplets. The presence of oxides was found to significantly increase the tendency to form spatter cold laps as well as overlap cold laps. Particularly for overlap cold laps, it was found that the depth (in transverse direction of weld) is reduced when welding in a non-oxidising environment. Welding on blasted surfaces increased the cold lap formation by entrapment of gas. The droplet and base metal temperatures were also found to be significant factors in cold lap formation. For overlap cold laps the occurrence frequency decreased with increased preheating temperature of the base metal. Mechanisms of overflowing resulting in overlap cold laps were discussed based on an extensive literature review. Several phenomena are believed to contribute to overflow including Rayleigh instability, the balance of forces, transfer of lateral momentum by droplets and an outward Marangoni fluid flow of the weld pool. The present studies suggest that cold lap formation can be suppressed by ensuring that the welding process (arc) is as stable as possible and by welding on a preheated work piece in a non-oxidising environment.

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Maia, Ivan Gonçalves. "Efeito da camada de nitreto na porosidade em soldas de eixos automotivos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263152.

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Orientador: Roseana da Exaltação Trevisan
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Visando solucionar o problema da ocorrência de poros em um cordão de solda de um eixo automotivo, o presente trabalho apresenta um estudo da influência de diferentes fatores na ocorrência de porosidade em juntas de aço soldadas pelo processo MIG/MAG robotizado. Basicamente, foi estudada a influência de três fatores na ocorrência dos poros. São eles, a presença de uma camada rica em nitretos na extremidade de um dos tubos que compõe a junta, a limpeza das superfícies a serem soldadas e a vazão do gás de proteção. Após a soldagem dos corpos de prova foram retiradas de cada um deles, três amostras da seção transversal do cordão de solda. A porosidade foi quantificada pela técnica de análise metalográfica por microscopia ótica. Os resultados de porosidade foram apresentados de duas maneiras, uma sem qualquer tipo de restrição quanto aos poros encontrados, e outra em que houve distinção quanto à localização dos poros na seção transversal do cordão de solda. Quando a porosidade foi quantificada de maneira geral, sem qualquer tipo de distinção quanto à localização dos poros, dois fatores influenciaram a ocorrência de poros na junta soldada. São eles, a presença da camada rica em nitretos e a vazão do gás de proteção. No outro caso, levando em consideração a localização dos poros na seção transversal do cordão de solda, foi constatado que para o caso dos poros localizados na raiz da junta, a presença da camada rica em nitretos gerada pelo processo de corte a plasma na extremidade do tubo correspondente ao metal-base 1 afetou significativamente a porosidade resultante no cordão de solda. Além dos ensaios experimentais, ensaios práticos foram realizados no próprio chão de fabrica de produção dos eixos. A realização de ensaios práticos visou avaliar a solução proposta para eliminação da ocorrência de porosidade no cordão de solda dos eixos. Os resultados destes ensaios comprovaram que a substituição do gás utilizado para o corte a plasma na extremidade do tubo correspondente ao metal-base 1, de ar comprimido por oxigênio puro, inibiu a formação dos poros
Abstract: In order to solve the occurrence of pores in weld beads of an automotive axle, the present work studies the influence of three different factors on the occurrence of porosity in joints welded by robotized GMAW process. The factors analyzed were: the presence of a region enriched by nitrides on the surface of the tube related to the base metal 1, the surface cleanliness of the joint components, and the shielding gas flow. Three samples of the weld bead transversal section were retired in each specimen. The porosity was quantified by metalographic analysis technique using an optical microscope. The results were presented by two different ways. In one of this ways, pores were quantified without any kind of distinction. In the other way, pores were grouped in accordance of their location in the weld bead transversal section. The pores quantified without any kind of distinction were affected by the ¿presence of the coat¿ and by the shielding gas flow. The pores located near the joint root were affected only by the ¿presence of the coat¿. In addition to the experimental specimens, practical experiments were made in the axles line production. These practical experiments were developed to evaluate a proposed solution to prevent the occurrence of the pores on the weld bead of the axles. The results of these practical experiments proved that changing the compressed air used in the plasma cut of the extremities of the tube related to the base metal 1 by pure oxygen gas inhibited the pores formation
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica

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8

Yeh, Felipe Wu Tzong. "Avaliação de descontinuidades no reparo em placas de aço por "Friction Hydro Pillar Processing" (FHPP) via ultrassom e micrografia." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/75898.

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Processos de soldagem por atrito apresentam diversas vantagens na união de materiais metálicos. O processamento de pinos por atrito ou “Friction Hydro Pillar Processing” (FHPP), é um exemplo de tecnologia de soldagem por atrito que pode ser utilizado no reparo de estruturas metálicas em ambientes hostis. Dependendo dos parâmetros de soldagem e dos materiais utilizados (pinos consumíveis e material base), as soldas FHPP podem apresentar defeitos como trincas na interface de união da junta e presença de inclusões. Tais defeitos e as tais inclusões comprometem a integridade mecânica e metalúrgica da solda, logo a inspeção utilizando ensaios não destrutivos é justificada. Utilizando o ensaio de ultrassom, soldas FHPP com chapas de aço ASTM A36 e pinos de aços ASTM A36 e SAE 8620 foram inspecionadas, variando somente as seguintes forças axiais do processo de soldagem: 200, 250, 300 e 350kN. Foi possível relacionar os resultados do ensaio de ultrassom com a localização de defeitos e inclusões nos corpos-de-prova e esses sinais foram validados através de micrografia das juntas estudadas.
Friction welding processes have several advantages in the union of metallic materials. The friction processing of pins or Friction Hydro Pillar Processing (FHPP), is an example of friction welding technology that can be used in the repair of metallic structures in hostile environments. Depending on the welding parameters and materials used (consumable pins and base material), the FHPP welds can present defects like cracks in the bond surface and the presence of inclusions. Such inclusions and defects compromise the mechanical integrity of the weld and therefore a inspection using nondestructive evaluation is justified. Using ultrasonic testing, FHPP welds using ASTM A36 steel plates and ASTM A36 and SAE 8620 steel pins were surveyed, varying only the axial forces in the welding process: 200, 250, 300 and 350kN. It was possible to relate the ultrasound testing results with the location of defects and inclusions in the specimens and those signals were validated by the micrography of the joints studied.

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CARVALHO, GILBERTO. "Determinacao de defeitos em profundidade (estereoradiografia)." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10938.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Brehovský, Patrik. "Svařování hlubokotažných ocelí s ochrannou vrstvou hybridní technologií Laser-TIG." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417119.

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The diploma thesis focuses on laser welding of extra deep-drawn steel sheet according to the standard WSS-M1A365-A14 with a protective zinc surface layer. A 0,9 mm thick steel sheet with a zinc layer with coating weight 50 g · m^-2 is welded by a hybrid welding method Laser-TIG. The laser, as the primary energy source, is used for welding the material. The arc, provided by a non-melting tungsten electrode, is used for preheating the material for melting and evaporation of the zinc layer. Based on the initial experiments, the magnitude of the laser power with the welding speed was chosen as a constant parameter. The magnitude of the electric current, as the variable parameter, was set up to 0, 20, 30 and 40 ampers for welding the lap and the butt welds. Only one piece of the each weld type combination was made. The welds were afterwards tested to verify their quality and material properties. The first differences between laser welding with or without TIG preheating were visible during the experiment. The positive effects of the laser welding with preheating by TIG were confirmed. The material properties of the joints achieved better values and a influence of the welding defects on the quality of the joints was reduced. The Laser-TIG is a good choice for welding galvanized steel sheets in the mass production of automotive industry and it could be improved by more researches.

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Books on the topic "Defects in welding"

1

Hidekazu, Murakawa, and Ma Ninshu, eds. Welding deformation and residual stress prevention. Amsterdam: Butterworth-Heinemann, 2012.

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A, Simonen F., U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering Technology., and Pacific Northwest National Laboratory, eds. RR-PRODIGAL: A model for estimating the probabilities of defects in reactor pressure vessel welds. Washington, DC: Division of Engineering Technology, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1998.

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A, Simonen F., U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research. Division of Engineering Technology., and Pacific Northwest National Laboratory (U.S.), eds. RR-PRODIGAL: A model for estimating the probabilities of defects in reactor pressure vessel welds. Washington, DC: Division of Engineering Technology, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1998.

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Qi, D. M. Effects of welding residual stresses on significance of defects in various types of welded joint. Manchester: UMIST, 1989.

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S, Dean R., Hennick A, U.S. Nuclear Regulatory Commission. Office of Nuclear Reactor Regulation. Division of Operational Events Assessment., and Parameter Inc, eds. Closeout of IE bulletin 79-03A: Longitudinal weld defects in ASME SA-312 type 304 stainless steel pipe. Washington, DC: Division of Operational Events Assessment, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, 1989.

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S, Dean R., Hennick A, U.S. Nuclear Regulatory Commission. Office of Nuclear Reactor Regulation. Division of Operational Events Assessment., and Parameter Inc, eds. Closeout of IE bulletin 79-03: Longitudinal weld defects in ASME SA-312 type 304 stainless steel pipe spools manufactured by Youngstown Welding and Engineering Co. Washington, DC: Division of Operational Events Assessment, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, 1989.

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Guthrey, Harvey. A model for electron-beam-induced current analysis of mc-Si addressing defect contrast behavior in heavily contaminated PV material: Preprint. Golden, CO]: National Renewable Energy Laboratory, 2012.

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Trafton, Maple. Practical Techniques : the Projection Welding and Troubleshooting Welding Defects: Projection-Welding. Independently Published, 2021.

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Deng, Dean Y., Yukio Ueda, Ninshu Ma, Hidekazu Murakawa, and Naoki Osawa. Welding Deformation and Residual Stress Prevention. Elsevier Science & Technology, 2022.

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Deng, Dean Y., Yukio Ueda, Ninshu Ma, Hidekazu Murakawa, and Naoki Osawa. Welding Deformation and Residual Stress Prevention. Elsevier Science & Technology, 2022.

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Book chapters on the topic "Defects in welding"

1

Mandal, Nisith R. "Welding Defects." In Ship Construction and Welding, 283–92. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2955-4_19.

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Han, Junling, Guannan Ren, Limei Peng, Hongyu Tian, and Pengbo Ji. "Analysis and Qualification Control of Welding Defects of Coated 15-15Ti Cladding Tube." In Springer Proceedings in Physics, 861–71. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_73.

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AbstractPhysical property test fuel rod is used for the engineering test and thermal comprehensive experimental verification of lead-cooled reactors. Preliminary electron beam welding (EBW) trials showed that the welding quality of coated 15-15Ti tube and 316L end plug were significantly affected by welding defects. By studying the welding defects with optical microscopy (OM) and scanning electron microscopy (SEM), it is showed that the inclusions in the coating of the cladding tube enter the welding line during EBW, increasing the tendency to form cracks and leading to welding cracks; the excessively long mating surface between the cladding tube and end plug results in welding gas expansion. Through the design of orthogonal tests with influential parameters including the length of the mating surface of the end plug, the removal amount of the inner wall of the cladding tube and the interference amount on the quality characteristics, the comprehensive effects of these parameters were studied and the best matching structure was determined, which breaks through the difficulty in the welding between 316L end plug and coated 15-15Ti tube, and the welding qualification has been verified to be improved.

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Katayama, Seiji. "Formation Mechanisms and Preventive Procedures of Laser Welding Defects." In Fundamentals and Details of Laser Welding, 87–111. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7933-2_5.

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Wang, Xuewu, Zhongwang Zhang, and Huafeng Liu. "Deep Learning Based Robot Detection and Grinding System for Veneer Defects." In Transactions on Intelligent Welding Manufacturing, 82–95. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3902-0_5.

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Ma, Rui, Peng Dong, and Zigang Xv. "Analysis on Fatigue Crack of Orthotropic Steel Bridge Decks." In Advances in Frontier Research on Engineering Structures, 287–93. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8657-4_26.

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AbstractThrough the detection of the steel structure bridge for 7 years, the main distribution of cracks in steel box girder of steel structure bridge was presented. Through the numerical analysis of the steel box girder of steel structure bridge, the stress distribution of the diaphragms was obtained. The result of detection and the numerical analysis was compared, and showed that the cracks mainly appeared in the welding parts and the arc notch of the diaphragms. The cracks at the welding part mainly came from the welding defects. And the cracks at the arc notch of the diaphragms were due to the stress concentration.

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Patel, Falak P., Bhumi K. Patel, and Vishvesh J. Badheka. "Welding Processes for Additive Manufacturing—Processes, Materials, and Defects." In Lecture Notes in Mechanical Engineering, 1013–29. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7787-8_80.

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Zhang, Zhifen, Guangrui Wen, and Shanben Chen. "On-Line Monitoring and Defects Detection of Robotic Arc Welding: A Review and Future Challenges." In Transactions on Intelligent Welding Manufacturing, 3–28. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8668-8_1.

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Li, Gang, Haiping Chen, Jingyuan Xu, Chao Chen, Na Lv, and Shanben Chen. "Development of a Low-Cost Arc Spectrum Sensor for Monitoring Pore Defects in Welding Process." In Transactions on Intelligent Welding Manufacturing, 75–92. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8668-8_4.

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Xu, Jingyuan, and Shanben Chen. "The Review of Spectrum Detection and Ultrasonic Vibration Control of Porosity Defects in Aluminum Alloy Welding." In Transactions on Intelligent Welding Manufacturing, 3–24. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7215-9_1.

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Yang, J., S. Gang, X. Li, Li Chen, and F. Xu. "Typical Joint Defects in Laser Welding of Aluminium-Lithium Alloy." In Proceedings of the 36th International MATADOR Conference, 595–98. London: Springer London, 2010. http://dx.doi.org/10.1007/978-1-84996-432-6_130.

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Conference papers on the topic "Defects in welding"

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Tsukamoto, Susumu, Isao Kawaguchi, Goro Arakane, Tomoyuki Kamata, and Katsuhiro Maekawa. "Suppression of welding defects in deep penetration CO2 laser welding." In ICALEO® 2000: Proceedings of the Laser Materials Processing Conference. Laser Institute of America, 2000. http://dx.doi.org/10.2351/1.5059447.

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"AN AUTOMATIC WELDING DEFECTS CLASSIFIER SYSTEM." In International Conference on Computer Vision Theory and Applications. SciTePress - Science and and Technology Publications, 2008. http://dx.doi.org/10.5220/0001075902600263.

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Lei, Xiao-chun, Ping Zhou, and Ru-xiong Li. "Analysis of Welding Defects in Spot Welding Process U-I Curves." In 2009 Third International Conference on Genetic and Evolutionary Computing (WGEC 2009). IEEE, 2009. http://dx.doi.org/10.1109/wgec.2009.110.

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Wei, P. S., K. C. Chuang, and J. S. Ku. "Spiking and Humping Defects in Laser Welding." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39513.

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Pitches of surface humps or coarse ripples and spikes affected by the focusing characteristics and scanning speed in high-intensity electron-beam welding or melting are quantitatively measured. Humping and coarse rippling are referred to surface roughness, which often accompanies with undercut, segregation, porosity and other defects. Spiking represents a sudden increase in penetration beyond the average penetration line. In this work, acceleration voltage and welding current of the electron beam welder used are 55 kV and 20 mA, whereas scanning speed is between 15–30 mm/s. Specimens are Al 6061, 1050, 1100 and 5083, and SS 304. This study found that humping and coarse rippling are enhanced by lowering the focal spot location. The measured amplitudes of humping are confirmed by successfully comparing with scale analysis.

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Jones, Marshall, Carl Erikson, Daniel Nowak, and Ganjiang Feng. "Laser hot-wire welding for minimizing defects." In ICALEO® 2004: 23rd International Congress on Laser Materials Processing and Laser Microfabrication. Laser Institute of America, 2004. http://dx.doi.org/10.2351/1.5060291.

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Li, Yan, Jian Shuai, Yan Zhou, and Kui Xu. "Failure Analysis of Pipeline With Pore Defects." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45351.

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During the welding process, the pore defects may be produced in the weld body. Statistic results showed that welding defect is one of the main causes for pipeline failure. According to this factor, this paper presents a detailed description of numerical research to assess the structural condition of circumferential weld seam pipeline with pore defects. Based on elastic-plastic theory, a set of nonlinear finite element analyses of pipelines with pore defects are carried out to study the influence of different sizes and locations on failure mode. Aimed at evaluating the load bearing capacity of pipeline with pore defects, limit stress states are investigated in this paper by using the finite element analysis. By comparing the present analysis results with the relevant standards, a proposed acceptance criterion is brought out. The results presented in this paper can be used to make suggestions on welding procedure qualification and continued safe operation of pipelines.

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Ajri, Abhishek, and Yung C. Shin. "Investigation on the Effects of Process Parameters on Defect Formation in Friction Stir Welded Samples via Predictive Numerical Modeling and Experiments." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-3092.

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Setting optimum process parameters is very critical in achieving a sound friction stir weld joint. Understanding the formation of defects and developing techniques to minimize them can help in improving the overall weld strength. The most common defects in friction stir welding are tunnel defects, cavities and excess flash formation which are caused due to incorrect tool rotational or advancing speed. In this paper, the formation of these defects is explained with the help of an experimentally verified 3D finite element model. It was observed that the asymmetricity in temperature distribution varies for different types of defects formed during friction stir welding. The location of the defect also changes based on the shoulder induced flow and pin induced flow during friction stir welding. Besides formation of defects like excess flash, cavity defects, tunnel/wormhole defects, two types of groove like defects are also discussed in this paper. By studying the different types of defects formed, a methodology is proposed to recognize these defects and counter them by modifying the process parameters to achieve a sound joint for a displacement based friction stir welding process.

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Bates, Philip J., Gene Zak, and Xiaochao Cao. "Weld Read-Through Defects in Laser Transmission Welding." In SAE 2011 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2011. http://dx.doi.org/10.4271/2011-01-0476.

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Liu, Xiao-Ming, Yun-Peng Gao, Zhi-Gang Wei, and Hou-Xia Yan. "Welding defects of SUPER304H steel and their countermeasures." In 2015 International Workshop on Materials, Manufacturing Technology, Electronics and Information Science. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789813109384_0001.

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Kan, Yusuf Can, and Habil Kalkan. "Automatic Detection and Classification of Laser Welding Defects." In 2021 Innovations in Intelligent Systems and Applications Conference (ASYU). IEEE, 2021. http://dx.doi.org/10.1109/asyu52992.2021.9599064.

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Reports on the topic "Defects in welding"

1

Ruschau. L51771 Alternative Acceptance Criteria of Girth Weld Defects. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 1997. http://dx.doi.org/10.55274/r0010187.

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The girth weld defect acceptance standards based on good workmanship reflect quality levels that can be reasonably expected from a qualified welder. Workmanship (WM) or weld quality standards specify a maximum allowable length whilst the percentage loss of cross-sectional area is used for porosities. This approach to defect acceptance philosophy has arisen from the use of radiography as the NDE technique for detecting and quantifyingweld discontinuities. The first WM standard for inspection and acceptance of finished girth welds was implemented by API in 1953. The specific requirements of the 1953-standard were largely based on the Unfired Pressure Vessel Code which was first adopted by ASME in 1931. Since then, a number of slightly revised standards were issued to reflect what should be attainable with normal good welding practices. The failure behaviour of defective girth welds in large diameter pipe lines was assessed using radiographic and mechanized ultrasonic inspection, small scale (tensile, hardness, Charpy and CTOD) and wide plate tests. The specimens were taken from girth welds in API 5LX70 pipe of 1219 mm (48 inches) in diameter by 8,0 mm (0,323 inch) and 13,3 mm (0,524 inch) wall. The test welds were made with the SMAW (8 welds) and GMAW (9 welds) welding processes. Upon completion of the non-destructive tests, 96 curved wide plate specimens were tested to destruction under tensile load. Testing was performed at low temperature (-50�C/-58�F). Defect type, defect position and size were determined from photographs of the fracture face and macro sections (defect characterization and sizing). In total, 290 typical surface breaking and embedded defects in SMAW or GMAW girth welds have been evaluated.

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2

Schipaunboord, W. N., M. A. Lont, and A. H. M. Kron. JTM-00-01 NDE Acceptance Criteria for Girth Defects Linked with Welding and Inspection Technique. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2001. http://dx.doi.org/10.55274/r0011796.

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Experimental work was conducted on two girth welds in large diameter steel pipes. By a proper selection of welding consumables, yield strength mismatch was obtained from 5 to 12% undermatching and 45% overmatching. The girth welds were non-destructively tested using the time of flight diffraction technique by three NDE companies. The verification of the detection and sizing capabilities of TOFD inspection techniques has shown that the performance levels varied widely. This finding confirms the need to validate the NDE techniques. Tensile specimens, Charpy and CTOD specimens, and curved wide plate testes were taken out of the welded pipes for testing the mismatch ratio, fracture toughness behavior and failure mechanisms. The wide plate tests were supported by an ECA using BS 7910. This work has reconfirmed the validity of the basic toughness and overmatch requirements given by EPRG for the application of the Tier 2 defect limits. The wide plate tests demonstrated that failure to satisfy one (or both) of these requirements results in a significant reduction of the acceptable defect length limit. The derivation of ECA-based NDE acceptance criteria is not specified in the present standards. The way to deal with the performance of welding technique, the NDE systems and its relation to ECA-based acceptance criteria is not prescribed. In the present Dutch project the derivation of ECA-based acceptance criteria will be validated by a probabilistic approach. This approach is based on Monte Carlo simulations by which the effects of weld defect population; the NDE performance and acceptance criteria on the repair rate and integrity level can be investigated.

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Wang. PGH376V A Comprehensive Update on the Evaluation of Pipeline Weld Defects. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2008. http://dx.doi.org/10.55274/r0010920.

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Girth weld defect acceptance criteria are set and enforced in pipeline constructions per federal regulations (CFR 49 Parts 192 and 195). With the increased use of mechanized welding and AUT (Automated Ultrasonic Testing) in new pipeline constructions, alternative defect acceptance criteria based on ECA (Engineering Critical Assessment) principles are frequently used in lieu of the traditional workmanship criteria that are in the main body of API Standard 1104. Unfortunately, the current alternative defect acceptance criteria of API 1104 Appendix A has not been kept up-to-date with new linepipe materials, welding processes, and pipeline service environments. The objective of this project is to provide technical basis for updating the alternative girth weld defect acceptance criteria in API 1104 Appendix A and other similar codes and standards. There are two focus areas in this project. The first focus area is to update the alternative defect acceptance criteria to address the immediate need of pipeline constructions in the U.S., typically with pipeline longitudinal strains less than 0.5%, or alternatively termed stress-based design. The materials in the new constructions are typically of micro-alloyed type and the grades are moving higher, up to X80 and X100. These materials did not exist when the current API 1104 Appendix A was adopted. Their behavior is sufficiently different that a fresh look in the current environment is needed. The second focus area is to develop a set of procedures that may be used for determining the girth weld defect acceptance level under high longitudinal strains ( greater than 0.5% and up to 2-4%).

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Begg, Darren. PR-214-124506-R02 Toughness and Strength of Sub-Arc Double Jointed High Strength Pipe. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 2017. http://dx.doi.org/10.55274/r0011418.

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Current design of pipelines calls for overmatching weld metal tensile strength, forcing deformation to occur in the base material and not in the weld. If straining of the weld metal were to occur, higher levels of weld metal toughness would be required to prevent fracture initiation from pre-existing defects. There are three known issues related to the Submerged Arc Welding (SAW) double jointing of pipeline steels: - Consistently achieving weld metal strength and toughness requirements. - Heat affected zone (HAZ) softening of the base material. - Lack of an accepted test protocol for the entire range of pipe grades. The results herein will help improve the quality and efficiency of SAW welding in double jointing for all pipeline steels, and enhance industry's ability to complete double jointing and standardize its acceptance, and will improve construction efficiency, pipeline reliability and safety by addressing this important research gap in transmission pipeline welding.

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Pope and Pope. L51653 Fracture Behavior of Girth Welds Containing Natural Defects Comparison with Existing Standards. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 1992. http://dx.doi.org/10.55274/r0010132.

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The first use of radiographic standards for inspection and acceptance of finished girth welds was adopted by API in 1953. This standard was largely based on the Unfired Pressure Vessel Code� which was adopted by ASME in 1931. At that time and to this day, weld defect acceptance standards are based on workmanship principles. In other words, the so called "Workmanship defect acceptance standards"� reflect the weld quality levels produced by. a trained welder using satisfactory materials, equipment and procedures. For many years exclusive use was made of the API 1104 workmanship defect acceptance levels for all field pipeline and related facilities welds. This, and very similar defect acceptance standards (e.g. BS 4515, CSA 2184, AS 1697, etc.) are used in many countries throughout the world. Though the specified acceptance levels have no scientific basis, the use of workmanship standards has provided an adequate level of quality control for many years. Particularly worthy of attention in this context is the fact that the currently stipulated levels have been developed for welds in lower strength pipe grades. Unfortunately, the developments in acceptance levels have not kept pace with those occurring in-pipeline technology. Furthermore, pipe size, strength and toughness, weld metal properties or pipeline operating conditions are not considered in the present-day defect acceptance standards. Problems of this kind have led companies involved in gas/oil transporting activities to develop their own standard requirements or at least to produce a supplement to the general standards. This report describes the results of an investigation into the engineering significance of girth weld defect acceptance criteria based upon weld quality (or workmanship) considerations. To this end, research efforts were divided into a theoretical and an experimental part. The theoretical study involved a comparison of internationally used weld quality standards and codes for pipeline welding in order to identify the general features common to them and to obtain a clear view of the different acceptability criteria. The experimental part was designed to provide factual information on the failure behaviour of defective girth welds in large pipe diameter pipe lines. The focal point of the experimental examinations was to compare, on the basis of wide plate test specimen behaviour, the performance levels of girth welds containing planar weld defects which were grossly out of tolerance with respect to most present-day weld quality (workmanship standards) specifications.

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Foley, W. J., R. S. Dean, and A. Hennick. Closeout of IE Bulletin 79-03: Longitudinal weld defects in ASME SA-312 Type 304 stainless steel pipe spools manufactured by Youngstown Welding and Engineering Co. Office of Scientific and Technical Information (OSTI), April 1989. http://dx.doi.org/10.2172/6344615.

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Bala. L51600 Engineering Critical Assessment of Girth Welds in Small Diameter Pipe. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 1989. http://dx.doi.org/10.55274/r0010101.

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Transmission pipeline girth welds are fabricated and inspected to rigorous material standards such as API 1104, CSA Z 184 and BSI 4515. These standards contain weld defect acceptance levels based on good workmanship criteria and have been arrived at on the basis of traditional welding and inspection practices. In certain instances, defects that do not meet the workmanship standards have been accepted on the basis of an engineering critical assessment (ECA) using the British Standard PD 6493 assessment technique. The use of ECA is now being incorporated into the pipeline codes. Four girth welds containing hydrogen induced cracking (HIC) defects at the root were prepared in small diameter (305 mm) thin wall (6.35 mm) X52 pipes using E6010 (E41010) electrodes for the root and hot passes and E7010 (E48010) electrodes for the fill and capping passes. The CTOD tests were performed for the girth welds using each of HIC as well as fatigue pre-crack for the crack. The minimum, the average and an intermediate (between minimum and average) CTOD value at -40C obtained for the specimens containing HIC were used to determine the surface crack sizes for the girth weld roots from BS PD6493. The girth weld containing the 1/4 thickness HIC was full scale tested at -40C. The test was terminated when the remote strain gauges showed plastic deformation/ buckling in the pipe. The second and third full- scale girth weld tests were carried out with the half wall and an intermediate (between 1/4 and 1/2 wall) wall defect. In both cases the girth failed when the remote strain gauge readings in the pipe were still elastic.

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Wang. L51841 Compendium of Pipeline Girth Weld ECA Methodologies to Support Revisions to Existing Code Practices. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2001. http://dx.doi.org/10.55274/r0010268.

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Significant progress has been made since the mid-1980's in understanding the role of weld defects in pipeline integrity. Unfortunately, this new knowledge has not been incorporated into Appendix A. More significantly, new line pipe materials and welding processes since the mid-1980's have created conditions that were not anticipated in the original code, and that can lead to unsafe designs. This project was commissioned to produce a document to provide the technical basis for the revisions of Appendix A. The technical and historical background of several internationally recognized girth weld ECA (Engineering Critical Assessment) procedures are reviewed. Some recent developments in further refining the girth weld ECA procedures are described, with particular emphasis on the work funded by PRCI. These new developments lead to the recommended revisions to API 1104 Appendix A. The Canadian code, CSA Z662 Appendix K, is the process of adopting some of these developments.

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Miller. L51659 Diverless Pipeline Repair Clamp I. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 1993. http://dx.doi.org/10.55274/r0010264.

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Offshore oil and gas developments are underway for water depths beyond which divers can function. The economic lifelines of these projects are the pipelines which will transport the products to shore. In preparation for the day when one of these pipelines will require repair because of a leak, the Pipeline Research Committee of Pipeline Research Council International, Inc. is funding research directed at developing diverless pipeline repair capabilities. Several types of damage are possible, ranging from latent weld defects on one end of the spectrum to damage resulting in parting of the pipe at the other end. This study is specifically directed toward laying the groundwork for development of a diverless pipeline repair clamp for use in repair of leaks resulting from minor pipedefects. The incentive for a clamp type repair is costs. When compared to replacing a section of pipe, either by welding or by mechanical means, the clamp type repair requires much less disturbance of the pipe, less time, fewer operations and less equipment.

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Payer. L51903 Damage to FBE and Liquid Epoxy Coating from Hydrogen Outgassing from Welds. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 2004. http://dx.doi.org/10.55274/r0010383.

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Hydrogen in welds and its affect on performance from the perspective of cracking and embrittlement of steels has been widely studied, and welding procedures have been developed to minimize the deleterious effects of hydrogen. The practical problem is whether hydrogen outgassing from welds causes damage to FBE and liquid epoxy coatings on pipelines. FBE coatings on longitudinal welds made at pipe mills have developed defects because of hydrogen outgassing. Field welds are often coated shortly after welding, inspected and either buried or submerged, and there is a greater chance for more hydrogen in the field welds than mill welds. If coating damage occurred by outgassing, the damage could go undetected and affect the pipeline corrosion control. The objectives were to examine hydrogen outgassing as a cause of damage to FBE and liquid epoxy coatings, to collect and contrast experience with hydrogen in longitudinal welds and circumferential welds, to quantify hydrogen pickup and release from steel pipe and welds. Methods and practices are identified to avoid damage to FBE and liquid epoxy pipeline coatings from hydrogen outgassing. The approach was to examine epoxy coatings applied over welds for damage from hydrogen outgassing and to conduct experiments to determine the amount and rate of hydrogen desorption (outgassing) from welds. The effects of hydrogen desorption on coatings was examined for commercial FBE and liquid epoxy coatings along with screening tests with liquid glycerol and clear epoxy. Hydrogen desorption was measured directly on welds, and a model was developed to describe the outgassing of diffusible hydrogen and the amount of diffusible hydrogen remaining in the weld.

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