Pipelines and Welding Technology

Welding is the most widely used technology by manufacturers to join metals and alloys efficiently and to add value to their products. The application of welding technology is strongly regulated by standards which are essential for ensuring quality, facilitating reliability, flexibility, and scalability, and for streamlining regulatory compliance. Training in welding technology should thus be at the forefront of the strategy of any vocational training school. The International Institute of Welding (IIW) is a welding organization in which international expertise in welding and related technologies is assembled. For several decades this organisation has been tracking manufacturing industry needs and trends and developing guidance documents and technology exchange mechanisms to support companies seeking to adopt best practices and standards in welding. IIW and EWF (European Welding Federation) have developed a comprehensive training, qualification and certification system, applied to both people and companies, harmonized on a worldwide basis. The system is based on harmonized training guidelines and a quality assurance methodology and has been developed in the frame of lifelong learning. The aim of this study was to evaluate the impact of the IIW/EWF system in the metalworking companies in Europe and verify if the system adds value to companies employing staff and/or workers that undergo the IIW/EWF training & qualification. A second objective was to analyse the impact qualified personnel has in productivity and quality in welding construction. The results show that the companies clearly perceive both in tangible and intangible benefits when employing workers with IIW/EWF qualifications.

Welding technologies are constantly evolving, and their applicability is expanding, considering also the construction domain. Steel structures benefit from the advances in welding technologies due to the use of thin gauge steel sheets which can now be connected at high quality and automatically. The resistance of the connection between the thin steel sheets is crucial for the durability and safety of a structure made of built-up thin-walled cold-formed steel elements. Generally, self-drilling screws or bolts are used for the connection between thin-walled elements, but the quantity of time and manpower necessary for a large number of connections demands an improved solution. Conventional welding techniques are unsuitable for joining thin sheets, ranging from 0.4 to 1.0 mm to thicker ones measuring 1.0 to 3.5 mm. This article compares the results of an experimental investigation into lap joints connected by spot welding and MIG brazing with the design code provisions. The study examines single-lap joints in steel sheets of 0.8, 1.0, 1.2, 1.5, 2.0 and 2.5 mm thickness, connected using these welding technologies. The results obtained are then compared with analytical relations and processed according to EN 1990. Depending on the thickness of the connected sheets, spot welding can lead to two failure modes: button pull-out fracture and interfacial fracture. MIG brazing, a welding technology that deposits material below the melting point of the base material, is known for its advantages, such as low energy consumption, spatter-free operation, high welding speed, and compatibility with thin sheet metals. However, its application in the structural engineering of cold-formed elements lacks documentation. In the study, the MIG brazed specimens failed in the heat-affected zone of the connection. The results indicate the dependence of the spot weld lap joint resistance on the connected sheets' thickness, while the resistance of the MIG brazed lap joints is influenced by the minimum thickness of the connected steel sheet. The study aims to demonstrate the feasibility of the proposed solutions, evaluate their performance, and establish the limits of their applicability. A statistical interpretation of the results highlights the precision and reliability of joint resistance.

After spending 24 years as a founding editor of the Journal Science and Technology of Welding and Joining (STWJ), Sir Harry Bhadeshia has decided to step down. Having served as founding co-editors ...

Cold‐formed channels are joined by means of spot welds to form various configurations. They are used in typical electrical cable and conduit supports, also in power plants. The present design procedures follow AISI specifications, which gives the allowable load per spot weld as a function of the thickness of connected plates. Tests were carried out to establish the distribution of spot weld capacity. It has been found that the strength strongly depends on technology of welding. It is recommended to review the AISI provisions and specify special allowable loads for spot welds connecting cold‐formed channels. The allowable loads could vary depending on type of connection (backto‐back, side‐to‐side, side‐to‐back) and technology of welding (degree of correlation between adjacent welds).

Continuous innovations in welding and additive manufacturing (AM) technologies have introduced challenges related to process stability and uncertainties in ensuring high quality. Given the high complexity and transient nature of these processes, effective online acoustic monitoring is crucial for ensuring manufacturing quality and improving processing efficiency. This paper first elucidates the principles of acoustic signal generation in welding and additive manufacturing. It then provides a comprehensive review of the application of acoustic methods for quality monitoring in these processes, covering both structural acoustic emission (AE) and airborne acoustic monitoring techniques. Finally, it summarizes the current challenges and issues faced by acoustic monitoring technologies in welding and additive manufacturing and outlines potential future development directions.

Cost calculation and optimisation of welded steel structures

Research status of high efficiency deep penetration welding of medium-thick plate titanium alloy: A review

Optimization design of main hinge joint structure based on weld failure analysis

The use in motor vehicles of lightweight metals such as aluminium and titanium provides a high strength-to-weight ratio, thereby lowering overall weight and reducing energy consumption and CO2 emissions. Aluminium alloys have thus become an important structural material especially high strength and ultra-high strength alloys such as AW 7020. Many studies have shown that the presence of an aluminium oxide (Al2O3) thin film formed naturally on aluminium alloys is detrimental to welding. This article further investigates the specific effect of the Al2O3 thin film on welding AW 7020 alloy. An analytical experiment of welded AW 7020 alloy using a pulsed metal inert gas (MIG) robotic weld machine is carried out. Four specimens were cut, butt welded, and examined. The weld parameters included pre-weld cleaning of the Al2O3, pre-, and post-weld heat treatment. Al2O3 was removed by wire brushing; preheating was conducted at a temperature of 130 °C; and natural ageing was conducted by post-weld heating at 480 °C for 2 h, followed by quenching in water at 90 °C for 8 h, reheated, and sustained at 145 °C for 15 h. The result shows that the presence of Al2O3 layer appears not to be detrimental to the weld with new welding technologies, therefore suggesting that it is not necessary to grind off the Al2O3 layer before welding. This finding implies that welding costs can be lowered and weld quality improved when new welding technologies are applied in the welding of high-strength aluminium alloys.

This study deals with the evaluation of butt welded-brazed joints of two plates with the thickness of 2 mm from EN AW5083-H111 alloy and titanium Grade 2 prepared by two different welding technologies: laser beam welding-brazing (LBWB) and gas tungsten arc welding (GTAW). ER4047 and ER4043 welding wires with the diameter of 1.2 mm were used as filler materials. The macrostructures, microstructures and mechanical properties of experimental weld joints were analysed and compared. In general, the strength of joints produced by LBWB was higher than the strength of GTAW samples. The highest tensile strength at the level of 245 MPa was measured for the experimental joint made by LBWB using following welding parameters: the laser power of 1800 W, the welding speed of 30 mm.s−1, the laser beam offset to Al-sheet of 400 µm and the wire feed rate of 2.4 m.min−1.

One of the alternative method for welding method is a friction stir welding (FSW), which was developed in 1991 at TWI (The Welding Institute) in the United Kingdom, initially especially for joining aluminum and its alloys [1]. This process consists in joining of materials in solid state, which eliminates the problems resulting from melting the material and its re-solidifying, such as, hot cracking, residual stresses and distortion created during conventional welding. In this process, the heat which plasticized the material is provided by rotating tool consisting of shoulder and pin. This tool penetrates into the base material and then moves along the welding line. As a result of the friction between tool and joining materials is generated a sufficient amount of heat allowing on mixed the base material and create FSW joint. Among the most important advantages of using the FSW method should be listed: relatively easy automatization (it is often possible to use conventional CNC machine), lower residual stresses in the welded joints and their very good mechanical properties (often exceed the mechanical properties of welded or riveted joints). Project FAST_FSW (Advanced techniques for the Fabrication of Airframe STructures using innovative friction stir welding (FSW) technology) is realized within consortium between PZL Mielec and research partner Czestochowa University of Technology. The main objective of the FAST_FSW Project is to develop friction stir welding technology to aircraft design and manufacturing for introduce fasteners free, lighter weight and lower cost aerostructures.

Laser welding process specification base on welding theories

Influence of weld technology on reliability and life to cathode in vacuum tube was studied by requests of microwave tube. The quality of weld technology quite affects the emission capability of cathode. The mode of weld quite affects thermal efficiency of cathode in vacuum tube. Thermal efficiency of cathode can increase availably by changing the weld technology on the heat transfer path. Thermal analysis and optimization design of cathode module for vacuum tube was carried out with the FEM in order to obtain required cathode temperature with lower heat power. The weld mode quite affects the cathode heat power, for example, the cathode heat power can reduce 28.6% with 8+8 laser spot welding. We have also built the life test system of TWT's electron gun structure of 8+8 laser spot welding, using this life test system, up to 30 years life of cathode is forecasted.

Super-alloy GH4169 and related welded structures were widely used in the aero-engine industry region. Vacuum electron beam welding is one of the most advanced welding technologies, and the influence of the mechanical property caused by the welding technology still needs further research. Firstly, the hardness, microstructure, and tensile properties of the GH4169 electron beam welded joint were tested. After electron beam welding and two-stage aging treatment, the weld zone was strengthened and its hardness is higher than that of the base metal zone. The microstructure characterization results showed that the grain size of the weld and heat-affected zone was larger than that of the base metal. The tensile results show that the static properties of the welded joint are similar to that of the base metal, and the residual height has no obvious effect on the static strength of the welded joint. The high-temperature creep properties of GH4169 electron beam welded joints with residual height were tested. The results show that residual height will lead to a transient fracture of welded joints under relatively safe service conditions. The fatigue performance of GH4169 welded joints with and without residual height was tested respectively. The results show that the fatigue life of the welded joints without residual height was about 10 times longer than that of the welded joints with residual height under the same stress level, and for the welded joint with residual height, the residual height position will become the main fatigue crack source.

According to Cr-Ni stainless steel, three different welding technology and the appropriate welding process parameters were selected. Three welded joints of Cr-Ni stainless steel were prepared. The microstructure in weld metal zone of Cr-Ni stainless steel under different welding methods was studied by X-fluorescent chemical composition analysis and microstructure analysis. The results show that alloy composition of the weld metal are different and distribute unequally under different welding methods, microstructure morphology and grain size of the weld layer are quite different. the structure of bottom is small amount of γ phase and a little δ phase are combined together and cover is γ phase and Cu-wealthy phases in the welds under TIG-MAG welding. the structure of bottom is coarse columnar crystal and cover is typical cellular dendrite in the welds under TIG- TIG welding. the structure of bottom is tiny equiaxial dendrites and columnar crystal and cover is some γ phase and a little δ phase are combined together in the welds under TIG-SMAW welding.