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Objective Clarify the reasons for the leakage and failure of the gas-gathering pipeline welds on an active shale gas platform in Sichuan. Methods Failure analysis of welds is conducted based on macroscopic morphology analysis, non-destructive testing, physical and chemical performance testing, metallographic structure analysis, and microscopic analysis of the weld area. Results There are many defects in the pipe section specimen, such as excessive welding reinforcement, undercut, overlap, and misalignment, which may lead to stress concentration in the welding area; prior to welding construction, due to weather conditions, a large amount of water containing rusts are easily generated on the inner wall and groove area of the pipeline. During welding, these rusts may enter the deposited metal, causing excessive hydrogen content in the weld zone diffusion and increasing sensitivity to hydrogen-induced cracking at the welded joint. Conclusions Hydrogen induced cracking (HIC) in the weld seam area occurs under the combined influence of the external environment, stress concentration of pipeline welds, and excessive hydrogen content in the weld area, a large number of HIC microcracks intermittently merging to form macroscopic cracking failure. [ABSTRACT FROM AUTHOR]

Temperature variation during the welding will cause different solid-state phase transformations in the welding area and result in a heat-affected zone (HAZ) between the weld metal (WM) and the base metal (BM). Depth-sensing indentation (DSI) is a doable technique to characterize mechanical properties of materials in the HAZ, which is usually not big enough for the fabrication of coupons for traditional tension tests. The basic idea of DSI technique is to push a hard tip into the surface of the material and then reveal its mechanical properties based on the response of the material. In this study, mechanical properties of butt welds of Q355D steel were investigated with DSI tests and reverse analytical approach. Different welding zones, including BM, subcritical HAZ, fine-grain HAZ, coarse-grain HAZ, top pass of WM and middle pass of WM, were distinguished by microstructures observed by scanning electron microscope (SEM). DSI tests were conducted on these welding zones. Mechanical properties were characterized based on load-penetration depth (P-h) curves obtained by DSI tests. These mechanical properties were adopted in finite-element (FE) simulation of DSI tests. P-h curves obtained by FE simulation agree well with results of DSI tests for all welding zones, especially for the loading curves. The agreement validates the applicability of DSI technique in characterizing mechanical properties of materials. Tension coupon tests were conducted on the BM and the middle pass of WM to verify the accuracy of the DSI technique. Variation of mechanical properties across the welding area were discussed in accordance with microstructures of materials in different welding zones. [ABSTRACT FROM AUTHOR]

Pressure pipelines are widely used in hydropower generation, oil and gas transmission, and other fields. After years of operation, a pressure pipeline needs regular maintenance to ensure its safety. At present, manual detection methods are unable to meet this demand. An automatic pressure pipeline detection technology is urgently needed to achieve improved efficiency and accuracy. On the basis of the above requirements, a wall‐climbing robot is designed for automatic pressure pipe inspection and maintenance tasks. Moreover, rapid nondestructive testing of welds on the inner surface of pressure pipelines was performed, and a weld tracking function was developed for wall‐climbing robots. We propose an algorithm framework for weld recognition and centerline extraction by combining computer vision technology with traditional image processing technology using visual images. The experimental verification of the wall‐climbing robot designed in this paper and the algorithm framework for weld recognition and centerline extraction were performed based on actual pressure pipelines. The results show that the algorithm framework developed based on the wall‐climbing robot equipped with an industrial camera for pressure pipeline weld detection can achieve greatly improved efficiency, and the actual weld identification accuracy can exceed 90%, which is very meaningful for practical applications. [ABSTRACT FROM AUTHOR]

Supercritical carbon dioxide (S-CO2) Brayton cycle system has advantages of high thermal-electric conversion efficiency, simple structure, compact equipment, and the system has been widely studied in the field of small modular reactor. However, the degradation of candidate materials due to corrosion in the service environment hinders the widespread application of this technology. The corrosion behavior and mechanism of materials play an important role in the engineering application of S-CO2 Brayton cycle. In order to study the corrosion problem of S30408 pipe in the S-CO2 environment, the corrosion behavior of the steel pipe was studied. Corrosion tests at 320 ℃ and 500 ℃ were carried out on S30408 pipe and its welds in S-CO2 environment. The corrosion specimens were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The effect of temperature on the corrosion products and corrosion mechanism of S30408 pipe and its welds in S-CO2 environment was analyzed. The experimental results show that after 320 h of corrosion, obvious corrosion, corrosion crack propagation, and corrosion material shedding occur in S30408 pipe and its welds. The corrosion of pipe and welds is caused by oxidation and carburization, which can cause alloy element consumption, microstructural change, rapid failure, and its corrosion products mainly comprise of iron and chromium oxides and carbides, as well as the oxide of Si. Corrosion on the inside of the pipe is more severe than on the welds, and the surface of the pipe is cracked. Corrosion products are shed from the inner wall of the pipe, and the shedding of the corrosion products is due to the cracking of the inner wall surface of the pipe and the sawtooth shape of the cross section. The mismatch between the thermal expansion coefficient of the corrosion products and the matrix, and the fact that the experiment is in flowing S-CO2 are the main reasons for the shedding of the corrosion products. Only large block scab-like corrosion products are produced in the welds at high temperature. At 500 ℃, obvious intergranular corrosion cracking occur in pipe and welds. The corrosion mechanism indicates that serious intergranular cracking will occur when the pipe exhibits slight surface corrosion at the temperature of 500 ℃. The strong permeability and dissolution capacity of S-CO2 make the corrosion cracks easier to expand physically. This kind of crack is easy to expand to the inside of the pipe, causing material failure, which poses a great threat to the safety of the pipe and the entire equipment.

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fatigue crack growth rates (FCGR) of multiple X100 pipeline steel welds and heat affected zones were measured in high-pressure hydrogen gas to investigate their behavior compared to lower strength pipeline welds. A total of five high strength welds and two heat affected zones (HAZ) were examined all of which were fabricated using the same X100 base material. Different welding wires and techniques were used to fabricate the welds to provide a variety of end products to evaluate susceptibility to fatigue in high pressure hydrogen gas. Residual stresses were measured for each weld and HAZ using the slitting method and the effect of residual stress on the stress intensity factor, Kres, was determined. Using Kres, the fatigue crack growth rate curves were corrected to remove the effects of residual stress by examining the influence of Kres on stress ratio, R. Comparisons were then made between the high strength welds, which were corrected for residual stress, and lower strength welds from the literature. It was found that the higher strength welds and heat affected zones exhibited comparable fatigue crack growth rates to lower strength welds, as the FCGR data of the high strength welds overlaid the lower strength welds. This suggests that despite distinct differences in strength and microstructure between the different welds, hydrogen-assisted fatigue crack growth susceptibility is similar. A comparison was made between the Kres measured in extracted coupons and residual stress estimates provided in relevant welded pipe assessment standards such as API 579-1/ASME FFS-1. It was found the residual stress values in the test coupons extracted from welded pipe were significantly lower than those expected in the intact welded pipes and highlights the importance in quantifying and removing coupon residual stresses when fatigue crack growth rates are measured and including expected weld joint residual stress when making structural assessments.

Fatigue crack growth rates (FCGR) of multiple X100 pipeline steel welds and heat affected zones were measured in high-pressure hydrogen gas to investigate their behavior compared to lower strength pipeline welds. A total of five high strength welds and two heat affected zones (HAZ) were examined all of which were fabricated using the same X100 base material. Different welding wires and techniques were used to fabricate the welds to provide a variety of end products to evaluate susceptibility to fatigue in high pressure hydrogen gas. Residual stresses were measured for each weld and HAZ using the slitting method and the effect of residual stress on the stress intensity factor, Kres, was determined. Using Kres, the fatigue crack growth rate curves were corrected to remove the effects of residual stress by examining the influence of Kres on stress ratio, R. Comparisons were then made between the high strength welds, which were corrected for residual stress, and lower strength welds from the literature. It was found that the higher strength welds and heat affected zones exhibited comparable fatigue crack growth rates to lower strength welds, as the FCGR data of the high strength welds overlaid the lower strength welds. This suggests that despite distinct differences in strength and microstructure between the different welds, hydrogen-assisted fatigue crack growth susceptibility is similar. A comparison was made between the Kres measured in extracted coupons and residual stress estimates provided in relevant welded pipe assessment standards such as API 579-1/ASME FFS-1. It was found the residual stress values in the test coupons extracted from welded pipe were significantly lower than those expected in the intact welded pipes and highlights the importance in quantifying and removing coupon residual stresses when fatigue crack growth rates are measured and including expected weld joint residual stress when making structural assessments.

The stress crack resistance (SCR) of high density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for two 1.5 mm HDPE GMBs and a range of welding parameters. Results are reported for both unnotched and notched seams as well as their corresponding sheet material. Unnotched seam SCR specimens are shown to preferentially initiate craze formation at the terminating edge of the squeeze-out bead, while incorporating potentially degraded areas, such as the seams heat-affected zone (HAZ), within the slow crack growth region of the specimen. In the short-term, little variation was observed between the majority of seams for the nine welding parameter combinations examined, with an average normalized seam SCR value (normalized with respect to the unnotched sheet SCR) of 0.3 ± 0.1, or about 30% of the SCR of the unnotched sheet. It is shown that squeeze-out geometry plays an important role in the SCR of fusion seams. Seams with weld track rippling, a known qualitative indication of overheating, were found to have average unnotched SCR values 45% lower than smooth weld track seams. Deleterious squeeze-out geometries are identified to provide a framework through which CQA engineers and researchers can more readily identify 'higher risk' seams with respect to stress cracking. [ABSTRACT FROM AUTHOR]

A complex of works was carried out on establishing the nature of distribution of non-metallic inclusions in the structure of metal of low-alloy welds. As a result of metallographic examinations, the values of the volume content of inclusions in the structure and their distribution by sizes were established. The rationality of using such an additional indicator as the distribution density for a more informative description of non-metallic inclusions when evaluating their influence on the mechanical properties of weld metal was shown. The use of fractal analysis to reveal the features of the distribution density of non-metallic inclusions in the weld metal was proposed. [ABSTRACT FROM AUTHOR]

A complex of works was carried out on establishing the nature of distribution of nonmetallic inclusions in the metal structure of low-alloy welds. As a result of metallographic examinations, the values of the volume content of inclusions in the structure and their distribution by sizes were established. The rationality of using such an additional indicator as the distribution density for a more informative description of nonmetallic inclusions when evaluating their influence on the mechanical properties of weld metal was shown. The use of fractal analysis to reveal the features of the distribution density of nonmetallic inclusions in the weld metal was proposed. [ABSTRACT FROM AUTHOR]

The stress crack resistance (SCR) and standard oxidative induction time (Std-OIT) reduction of high- density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for a 12-year old 1.5 mm HDPE GMB when welded using nine welding parameter combinations. The GMB experienced a decrease in Std-OIT from 135 to 87 min between manufacturing and welding. Welding did not significantly decrease the Std-OIT in the heat-affected zone (HAZs). In general, individual seam SCR failure times fell between the notched and unnotched sheet, with adhered squeeze-out bead seams exhibiting individual failure times closer to the notched sheet and an average time until nominal failure (tNF) ∼21%–35% shorter than the unnotched sheet. Differences in tNF are attributed to residual stresses and (or) accelerated craze formation in seams with adhered squeeze-out beads. Non-adhered squeeze-out seams exhibited a slower tNF similar to that of the unnotched sheet, indicating a seam tNF less than that of the sheet may not be intrinsic to all HDPE fusion seams. High sheet temperatures at the time of welding and higher heat-applied welding parameters are thought to increase the likelihood of squeeze-out bead adherence. This paper shows that squeeze-out adherence can have a deleterious effect on seam SCR. [ABSTRACT FROM AUTHOR]

The difference in seam squeeze-out antioxidant loss (in terms of standard oxidative induction time, Std-OIT loss) and thickness reduction are evaluated for three different 1.5 mm-thick high density polyethylene (HDPE) geomembranes (GMBs) seamed using a variety of welding parameters and two different wedge welders. Partial squeeze-out antioxidant loss was detected in seams created from each of the three materials examined, with the majority off loss occurring when seam thickness reductions fell between 0.4 mm and 0.8 mm. Seams with thickness reduction exceeding 0.8 mm were found to exhibit greater squeeze-out Std-OIT loss, with near full Std-OIT depletion for one material. Wedge welder size was found to influence this relationship, some seams created with the large wedge welder exhibiting a near full Std-OIT depletion from squeeze-out at approximately 0.6 mm thickness reduction. Variation in seaming pressure and high load melt index (HLMI) were found to shift the degree of thickness reduction a seam may experience for a given welding speed and temperature, with higher seaming pressure and HLMI values generally resulting in greater thickness reduction. Although, for a given welding speed, wedge temperature, and sheet temperature combination, changes in seaming pressure had a limited effect on squeeze-out Std-OIT loss. This paper provides a rational basis into defining a practical 1.5 mm fusion seam thickness reduction criteria based on limiting antioxidant loss within a seam's squeeze-out and also provides a framework for identifying potentially higher risk fusion seams for future research. • First detailed evaluation of relationship between seam squeeze-out antioxidant loss and thickness reduction. • First detailed evaluation of effect of choice of welding parameters and wedge welder. • Provides a rational basis into defining a 1.5 mm fusion seam thickness reduction criteria based on limiting antioxidant loss. • Provides a framework for identifying potentially high risk fusion seams. [ABSTRACT FROM AUTHOR]

Numerical analysis is conducted to investigate the behavior of double shear combination connections made with pretensioned high-strength bolts and longitudinal fillet welds. The finite element (FE) models were validated using the results of an experimental investigation and utilized to develop a better understanding of the influence of critical input parameters on the connection behavior. Slip-dependent surface frictional and weld ductile fracture models were incorporated into the numerical models to simulate the nonlinear behavior of the connections. The numerical simulations confirm that at low slip displacements, the force carried by the combination connection can be estimated as the summation of the friction resistance introduced by the pretensioned bolts and the shear force carried by the fillet welds. The results also indicate that the behavior and capacity of the combination connection are not sensitive with respect to the weld location compared to the center of gravity of the bolts as long as no eccentricity is introduced within the force transfer mechanism. The paper also investigates the stress distribution within the connection plates and studies the effect of fillet weld size on the behavior of combination connections. • Comprehensive approach for modeling the nonlinear behavior of combination connection. • New surface frictional models are developed to capture the slip behavior of the connections. • Ductile fracture models are utilized to properly simulate the behavior of weld lines. • Large set of experimental investigations is used to validate the finite element models. • The effect of dimensions and location of weld lines on the behavior is quantified. [ABSTRACT FROM AUTHOR]

The present work is performed on the main steam pipe system in Heleneholmsverket, a CHP in Sweden and consists of the following parts (i) numerical analysis of the in-service creep behaviour of the pipe system, (ii) creep testing of new and service exposed materials from welded components, (iii) characterisation of the creep damage distribution in creep tested welds of the actual piping. The entire system has been modelled for creep evaluation to make it possible to compare the simulated creep stress and strain distributions in selected welds with observed amounts of creep cavitation, which can be correlated to the accumulated creep strain. Creep data for the analyses were produced by creep testing of service exposed base and weld metals from a pipe weld and a T-piece branch weld from the system. In addition, the creep tested welds were studied metallographically to map the creep damage and make it possible to compare the damage development with the resulting creep stress and strain distributions in the weld. In the previous project also a T-piece branch weld was investigated in a similar way and those results were used for verification of the re-analyses in present project with the updated system model. The following results were achieved: The model of the entire steam pipe system was created in Abaqus and the strain distributions were verified in comparison to a corresponding elastic Caepipe model. The Norton creep law was used for the simulations. In addition, also primary creep was analysed. The effects of primary creep on the long-term creep behaviour was significant and the results shows the importance of including primary creep into the model. There is no effect of starts and stops on the stress and strain distributions in the system during creep. The system analysis results showed enhanced strains up to 2.1% at one bend and 0.5–1.0% in some parts of the system. Although replica testing had not been conducted directly at the bend the high strains indirectly agreed with the observations of small creep cracks had been observed in replica testing of in a weld at one of the ends of the actual bend. Furthermore, several components in the system have been exchanged due to creep crack formation. Moderate levels creep damage was observed in the pipe weld. The analysis of this pipe weld gave somewhat lower creep strains than expected. The stress and strain distributions matched with the maximum principal stress criterion but not with the von Mises stress that Abaqus uses for creep analyses by default. The analysis of the branch weld matched well with observed creep damage distributions whereas the maximum strain level of 0.4% appears to be rather low in comparison to the quite extensive creep damage. However, local constraint and multiaxiality in welds lead to significantly lower creep ductility compared to uniaxial creep and contribute to a reasonable agreement between the strain and the damage levels. The creep tests of service exposed material resulted in relatively high Norton creep law exponents and no shift to lower values at the lowest tested stresses. It is hardly possible to perform tests at even lower stresses and therefore the simulations at service conditions resulted in unreasonably low creep strains. [ABSTRACT FROM AUTHOR]

A method is proposed for analysis of the stress–strain state of welds in large rolling-stock components, using SolidWorks/Simulation software. [ABSTRACT FROM AUTHOR]

This investigation concerns the application of the profilometry‐based indentation plastometry (PIP) methodology to obtain stress–strain relationships for material in the vicinity of fusion welds. These are produced by The Welding Institute (TWI), using submerged arc welding to join pairs of thick steel plates. The width of the welds varies from about 5 mm at the bottom to about 40–50 mm at the top. For one weld, the properties of parent and weld metal are similar, while for the other, the weld metal is significantly harder than the parent. Both weldments are shown to be approximately isotropic in terms of mechanical response, while there is a small degree of anisotropy in the parent metal (with the through‐thickness direction being slightly softer than the in‐plane directions). The PIP procedure has a high sensitivity for detecting such anisotropy. It is also shown that there is excellent agreement between stress–strain curves obtained using PIP and via conventional uniaxial testing (tensile and compressive). Finally, the PIP methodology is used to explore properties in the transition regime between weld and parent, with a lateral resolution of the order of 1–2 mm. This reveals variations on a scale that would be very difficult to examine using conventional testing. [ABSTRACT FROM AUTHOR]

Introduction. The research materials devoted to the operability assurance of welded structures of hazardous technical devices — components of oil and gas production equipment are summarized. The factors determining the operational strength of welded joints and structures are systematized and diagrammed. The causes for the decrease in their service properties are described. We have defined the role of volumetric and crack-like welding defects, which were not detected during quality control at the manufacturing stage and in determining the residual life while in operation, in ensuring the life cycle of the structure. Measures to improve the practice of detecting crack-like defects under visual- and-dimensional and ultrasonic methods of quality control of welded joints are proposed.Materials and Methods. In accordance with SNiP 2.05.06–85, the structures of main oil and gas pipelines, vertical cylindrical tanks, and other oil and gas production equipment (OGPE) are made of dead-killed and semikilled low- carbon and low-alloy steels with tensile strength of up to 686.5 MPa. Regardless of the class and strength level of steel, it should be well welded by all methods prescribed by standard process documentation (SPD). At the same time, regardless of the state of supply, the carbon equivalent Сэкв should not exceed 0.46 %. The research methods are calculation-experimental ones. To calculate the stress-strain state of welded joints, the following methods were used:finite elements (FEM),fracture mechanics using the stress intensity coefficient Kt.Methods of mathematical statistics were used to estimate the geometric dimensions of crack-like welding defects. Welding defects were detected by standard quality control methods prescribed by the SPD and GOST standards.Results. Welded structures operating in the fatigue mode are considered. Some factors characteristic of welded joints are analyzed. It is shown how they affect the formation of strength performance properties. The role of dangerous crack-like defects, which with high probability can be formed in welded joints in the manufacture of structures and during operation, is established. Often, the reason is a decrease in mechanical properties due to aging and loss of plasticity caused by accidental mechanical actions. Note that it is impossible to identify these defects by existing quality control methods, both during the control process under production and during diagnostics while in operation. This reduces the accuracy of predicting the operational life of the welded structure.Discussion and Conclusion. It is proposed to include the following requirements in the SPD:to the quality of welded joints of hazardous technical devices of OGPE,to detection of sharp crack-like defects with a radius of curvature in the range of 1-0.25 mm.However, the reliability of detection of such defects by the control methods used remains low due to the human factor. To increase the reliability of detection of sharp crack-like defects, the directions of improvement of ultrasonic quality control of welded joints are determined.

Copyright of Technical Diagnostics & Nondestructive Testing / Tekhnicheskaya Diagnostika I Nerazrushayushchiy Kontrol is the property of International Association Welding (Paton Publishing House) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Crosspoint of spiral and girth welds of spiral steel pipelines transporting high-pressure oil and gas is easy to crack due to welding defects and corrosion, so routine excavation and careful inspection are required. In order to reduce the workload and cost of excavation, it is necessary to determine the crosspoint’s angular position on the girth weld. This article proposes a low-cost and high-efficiency method for locating the spiral-girth weld crosspoint based on the inner Spherical Detector (SD). Theoretical analysis and experiments demonstrate that the magnetometer with a smaller lift-off could detect more noticeable magnetic valley of the spiral welds at the pipe bottom, so a smaller SD should be used; the spiral direction can be determined by the phase difference of the dual-channel magnetic signals, when dual magnetometers are symmetrically fixed about the median vertical plane on the rotation axis of the SD. When the girth weld, at least one spiral weld and the spiral direction are detected and determined, the crosspoint’s angular position can be calculated. The maximum localization error of the crosspoint is less than 30° and the average error is less than 20°, that is, no more than one hour’s angle, whose accuracy is sufficient for excavation and maintenance in the field, because it will reduce the amount of excavation by nearly half.

The main criterion for the performance of welds is the strength. The least durable are the corner joints used to perform various types of welded joints. In the literature, the methods of calculating the strength of welded joints with solid seams are considered in sufficient detail. Methods of calculation of connection interrupted sutures absent. In this case, the greatest difficulty is the calculation of connections using circular intermittent seams, which are often performed in welded drums and pulleys. They work on torsion. Therefore, the development of methods for calculating circular intermittent seams for torsion is quite important. Shear stresses in welds from torque are determined depending on the value of the polar moment of resistance of its dangerous section. When determining the polar moment of resistance of the dangerous section of a circular discontinuous seam, it was represented by a set of sections in the form of a sector of a circular ring. The method of calculation of the polar moment of resistance of the rotated dangerous section of a circular discontinuous weld, which takes into account the relative length of the weld areas and their number, is proposed, as well as the method of accurate and approximate calculation of shear stresses in the weld.

The analysis of metallurgical methods that improve the quality of electrodes for manual arc welding of low-carbon and low-alloy cold-resistant steels is presented. It is shown that it is possible to increase the technological and operational properties of welded joints at ultralow climatic temperatures down to –70°C to the level of world analogs by microalloying the weld metal with nitrogen, titanium, cerium oxide, and diamond nanoparticles of detonation origin. The composition of the modifying mixture introduced into the electrode coating is revealed. The cumulative effect of its constituent components on the impact toughness of the weld metal on 10KhSND steel was established during tests in the temperature range from –20 to –70°C. The weld metal structure consists mainly of dispersed acicular ferrite, reinforced with nanoparticles, presumably nitrides and carbonitrides of titanium and aluminum. It is shown that the centers of crystallization for acicular ferrite are microsized nonmetallic inclusions formed on superdispersed titanium nitrides. It was revealed that the impact toughness of the weld metal at below-zero climatic temperatures exceeds its values for seams welded using the massively imported LB-52U electrodes of the Japanese company KOBELCO. The results of the performed research make it possible to increase the cold resistance of welded structures for petrochemical and special purposes, based in the regions of the Far North of the Russian Federation. [ABSTRACT FROM AUTHOR]

Developments in the assembly and welding of large railroad-car components are considered. The introduction of a new aluminum-alloy freight-car body is discussed. [ABSTRACT FROM AUTHOR]

The traditional approach of assuming that the throat of the fillet weld resists the load, regardless of the direction of loading is followed in Indian steel code IS 800. However, based on experimental research, the American Structural Welding Code-Steel, the American Institute of Steel Construction code, and the Canadian code have modified the equations to consider the direction of loading. These provisions are discussed, and three examples are also included to show that economic design of weld material can be achieved by using these provisions. Although the end fillet may resist more loads, it may have less ductility than the side fillet. Hence, the designer should exercise caution while using the end fillet, especially when ductility is required in situations where overloading is likely to occur. [ABSTRACT FROM AUTHOR]

A calculation method is outlined for permanent (welded) joints in large aluminum-alloy freight-car components, using PropertyManager software. [ABSTRACT FROM AUTHOR]

The paper presents the results of studying the features of weld formation at consumable electrode pulsed-arc welding of 4 mm AMg5M alloy in diff erent positions at the speed of 23 m/h. with forming backing element (FBE) and without it. It is shown that sound welds form irrespective of the angle of butt joint inclination relative to the horizontal plane. FBE presence increases the geometrical dimensions of weld made with consumable electrode by 4 – 12% on average, depending on the position of butt joints. Obtained data clearly demonstrates the possibility of achieving the required quality of welds and high level of mechanical properties in consumable electrode welding of aluminium-magnesium alloys at diff erent positions of the butt joints without FBE application. 6 Ref., 3 Tabl., 4 Fig. [ABSTRACT FROM AUTHOR]

The majority of existing structures contain welded joints. Questions of monitoring service characteristics of welded joints, using acoustic emission method are considered. Attention is given to a change in material properties of operating structures with welded elements after long-term service, taking into account the time and probable violation of service conditions. Examples of evaluation of the change in properties of welded structure materials by the data of acoustic emission, determination of their damage and residual service life, are given. 17 Ref., 5 Tabl., 24 Fig. [ABSTRACT FROM AUTHOR]

The paper presents the results of studying the features of weld formation at consumable electrode pulsed-arc welding of 4 mm AMg5M alloy in different positions at the speed of 23 m/h with forming backing element (FBE) and without it. It is shown that sound welds form irrespective of the angle of butt joint inclination relative to the horizontal plane. FBE presence increases the geometrical dimensions of welds made with consumable electrode by 4–12 % on average, depending on the position of butt joints. Obtained data clearly demonstrates the possibility of achieving the required quality of welds and high level of mechanical properties in consumable electrode welding of aluminium-magnesium alloys at different positions of the butt joints without FBE application. 6 Ref., 3 Tables, 4 Figures. [ABSTRACT FROM AUTHOR]

The majority of existing structures contain welded joints. Questions of monitoring service characteristics of welded joints, using acoustic emission method, are considered. Attention is given to a change in material properties of operating structures with welded elements after long-term service, taking into account the time and probable violation of service conditions. Examples of evaluation of the change in properties of welded structure materials by the data of acoustic emission, determination of their damage and residual service life, are given. 17 Ref., 5 Tables, 24 Figures. [ABSTRACT FROM AUTHOR]

In this paper, Artificial Intelligence (AI) algorithms are employed for first, automating the process of creating a large synthetic Total Focusing Method (TFM) imaging dataset using a small set of Finite Element (FE) simulation datasets, and second for the automated defect-recognition (ADR) in butt-welds. In this paper, six types of imaging datasets are created with three approaches. In the first approach, weld TFM images are constructed using ultrasonic A-scan signals obtained from Full Matrix Capture (FMC) performed using FE analysis on models with weld defects (porosity and slag). The second approach generates near real-time weld TFM images by implementing fast deep convolution generative adversarial networks (DCGAN). This second technique permits simulations that are several orders faster when compared to the FE method. In the third approach, noise is extracted from FMC-TFM experimental measurements using the sliding kernel approach, and this noise is supplemented to individual simulated datasets for creating near to realistic scenarios. The first dataset is created using the first approach. The second dataset is created using the second approach, and the third hybrid dataset is a combination of FE and DCGAN weld TFM imaging. The fourth dataset is noise supplemented to FE based dataset. The fifth dataset is generated by adding noise to DCGAN images. The sixth hybrid dataset with noise is a combination of FE and DCGAN weld TFM noise images. AI plays a significant role in object detection and classification through robust feature extraction, reducing human intervention. In this work, for automated weld defect recognition, a convolutional neural network (CNN) is trained using six types of simulation-assisted weld TFM imaging datasets, which improves the reliability and efficiency of welds quality assurance. The mAP value is 85% for the ADR model trained using the hybrid weld TFM dataset with noise. The model prediction on classification on the hybrid dataset for porosity is 0.86 F1-score, and for slag is 0.80 F1-score. [ABSTRACT FROM AUTHOR]

Chromel-alumel thermocouples were used to study the temperature state of 10 mm copper plates at simulation of the process of friction stir welding. Thermocouples were welded on in blind holes located along the line of welding tool displacement that allowed recording the copper temperature at the moment of weld formation under different welding conditions. In the studied range of variation of process parameters, the metal temperature is mainly influenced by the area of interaction of the welding tool working surface with the plate, while the speed of tool rotation has a minor effect. At the moment of weld formation the metal temperature varied from 528 up to 980 in different modes. [ABSTRACT FROM AUTHOR]

Chromel-alumel thermocouples were used to study the temperature state of 10 mm copper plates at simulation of the process of friction stir welding. Thermocouples were welded on in blind holes located along the line of welding tool movement that allowed recording the copper temperature at the moment of weld formation in different welding modes. In the studied range of variation of process parameters, the metal temperature is mainly influenced by the area of interaction of the welding tool working surface with the plate, while the speed of tool rotation has a minor effect. At the moment of weld formation the metal temperature varied from 528 up to 980 °C in different modes. 13 Ref., 3 Tables, 3 Figures. [ABSTRACT FROM AUTHOR]

Fracture resistance of pipeline welds from a range of strength grades and welding techniques was measured in air and 21 MPa hydrogen gas, including electric resistance weld of X52, friction stir weld of X100 and gas metal arc welds (GMAW) of X52, X65 and X100. Welds exhibited a decrease in fracture resistance in hydrogen compared to complementary tests in air. A general trend was observed that fracture resistance in 21 MPa hydrogen gas decreased with increasing yield strength. To accommodate material constraints, two different fracture coupon geometries were used in this study, which were shown to yield similar fracture resistance values in air and 21 MPa hydrogen gas; values using different coupons resulted in less than 15% difference. In addition, fracture coupons were removed from controlled locations in select welds to examine the potential influence of orientation and residual stress. The two orientations examined in the X100 GMAW exhibited negligible differences in fracture resistance in air and, similarly, negligible differences in hydrogen. Residual stress exhibited a modest influence on fracture resistance; however, a consistent trend was not observed between tests in air and hydrogen, suggesting further studies are necessary to better understand the influence of residual stress. A comparison of welds and base metals tested in hydrogen gas showed similar susceptibility to hydrogen-assisted fracture. The overall dominant factor in determining the susceptibility to fracture resistance in hydrogen is the yield strength. • Fracture resistance of pipeline welds in hydrogen decrease with increasing strength. • In H 2 , welds and base metals of similar strength exhibit similar fracture behavior. • Two coupon geometries were used which yielded similar fracture behavior. • Strength exhibited more dominant factor in fracture than welding technique. [ABSTRACT FROM AUTHOR]