Pipe Welds Research Articles

Evaluation of Applied Destructive and Non-destructive Tests in the Technical Inspection Process of High-Frequency Electric Resistance Weld Pipes

Ensuring the absence of structural defects in metal pipes of the gas network requires production control and quality control tests. On the other hand, the main role of these pipes is the transmission of natural gas, therefore, the smallest leakage, along with damage to the environment and loss of natural gas, entails the dangers of explosion. In this article, all the quality tests performed on the raw materials and the metal pipe production process are mentioned, and the result of their optimization in terms of sampling, prototyping, and acceptance criteria in the quality control plan is given. In addition to destructive tests, three important non-destructive methods including industrial radiography, ultrasonic test, and eddy current test have been specially investigated. The statistical results of detectable defects for three specific sizes of pipes including 4, 6, and 8 inches have been collected. The final result of this essay is the optimization of high-frequency electric resistance welding pipe production.

Numerical simulation of temperature distribution and residual stress in TIG welding of stainless-steel single-pass flange butt joint using finite element analysis

Abstract Controlling defects such as deformation in the weld joint and the residual or superfluous stresses due to tungsten inert gas (TIG) welding or arc welding is a major concern for many industries like aeronautical, automobiles, nuclear or atomic power plants, crude oil or fossil fuel industries where pipes are in use and circumferential welding is done. Arc welding is a metal joining process, and TIG welding is applied to many industrial sectors that require high-quality welding. Simulation has been done on single-pass TIG welding on the Flange pipe of SS316 to evaluate transient temperature, residual stresses, and distortion. First, a 3D model is developed and assembled in SolidWorks. Second, in an MSC Patran, preprocessing of the FE model is done. Finally, in MSC Marc, thermal and mechanical simulation is performed. Based on this simulation, the accuracy of welding of the flange–butt joint made of SS316 is validated. In this study, the information regarding simulation of temperature dispensation and residual or superfluous stresses is done on the flange–butt joint, and it found the stresses are compressive at the weld bead area, and along the transverse direction, stresses changed to the tensile. The experimental data show that the steep curve at 0.00 mm represents a maximum temperature near the weld path at approximately 2,352°C, and the slant curve shows the far away points from the weld path. Comparing it with FE analysis, the maximum temperature attained was around 2,539°C. An approximate deviation of 7.365% was observed. The results of the study will provide experimental and simulation analyses for the welding of pipes of stainless steel for the transportation of oil and gases in the petroleum industries.

SIMULATION OF PREHEATING AND HEATING WHEN CONNECTING POLYETHYLENE PIPES WITH ELECTROFUSION COUPLINGS

Existing machines for electrofusion welding of polyethylene pipes provide a high-quality connection at air temperatures no lower than minus 10 °C. However, if welding is required at lower temperatures, a layer of heat-insulating material is used to reduce the cooling rate. This insulation is selected based on the air temperature and the size of the welded pipes. This paper investigates the dynamics of temperature fields at the stages of heating, temperature equalization and heating using a new technology of welding at low temperatures. The proposed technology eliminates the use of thermal insulation material and allows welding to be carried out automatically.The paper presents a mathematical model that describes the thermal process when performing all welding operations at low temperatures. The model describes the thermal process with and without phase transformation. The well-known method of end-to-end calculation with the introduction of effective heat capacity is used to consider the heat of phase transition in the temperature range. The model also considers the dependence of the thermophysical properties of polyethylene on the degree of crystallinity.The following text presents the results of preheating and temperature equalization calculations for welding polyethylene pipes of the PE 100 SDR 11 brand with a diameter of 160 mm at an air temperature of minus 40 °C. To accurately describe the thermal process of real welding, experimental temperature data was used for parametric identification. It is shown that as a result of preheating and temperature equalization in the weld and thermally affected zones and outside them at a distance of more than 10 mm, the temperature values do not exceed acceptable limits. The resulting temperature distribution allows heating according to the standard welding mode. Calculations show that when the heating is completed, the volume of the polyethylene melt corresponds to the volume of the welding melt at the allowed air temperature.These findings can be used to develop a technique for controlling the movement of the crystallization front during welding at low temperatures.

Application of ANN concepts for prediction of crack growth and remaining life of circumferentially cracked piping components under different loading scenarios

This paper presents the details of Artificial Neural Network (ANN) based models to predict crack depth and remaining life of circumferentially part-through cracked piping components used in the nuclear industry. Crack growth data from experimental studies on (i) straight pipes made up of SA 312 Type 304 LN stainless steel having part-through circumferential notch under combined bending and torsion and (ii) dissimilar metal pipe weld joints having circumferential through-wall crack in the weld were used. The dissimilar metal pipe weld joint is made up of SA312 Type 304 LN austenitic stainless steel and SA508 Gr. 3 Cl. 1 low alloy carbon steel and joined by Nickel-rich Inconel alloy weld. About 75 % of the mixed experimental data has been used for development of model and the remaining data for validation. For the development of ANN model, (i) back propagation technique (ii) sigmoidal transfer functions and (iii) Levenberg-Marquardt algorithm are used. The maximum percentage difference observed between the predicted and the experimental results for crack depth and remaining life was 19.59 % and 15.78 % respectively. The efficiency of the developed model was verified using several statistical parameters. The developed models are useful for the structural integrity assessment of piping components under different loading scenarios.

Pelatihan Pipe Welder Kepada Karyawan PT. Perintis Makmur Indonesia Dengan Metode Pengelasan Shielded Metal Arc Welding

PT. Perintis Makmur Indonesia (PMKI) is a smelting company that plays an important role in workforce absorption in the Morowali area. In particular, the mechanical department, consisting of 18 employees, requires an upgrade in pipe welding skills using the SMAW welding method. This is due to the fact that the mechanics are currently only capable of performing plate-to-plate welding, whereas they are required to have pipe-to-pipe welding skills to support their work. To enhance its employees' competencies, particularly in pipe welding, PT PMKI collaborated with the Morowali Metal Industry Polytechnic to organize a Shielded Metal Arc Welding (SMAW) training program for its employees. The primary goal of this training was to improve the employees' skills in performing pipe welding safely and efficiently. The training methods included lectures, discussions, and hands-on practice in the workshop, along with evaluations through pre-tests and post-tests. A total of 18 mechanics participated in this five-day training. The materials covered welding safety, SMAW techniques, and defect handling in welding. The results showed a significant increase in participants' understanding and skills. The initial understanding level, as measured by the pre-test, was only 19.8%. After the training, participants' understanding increased to 93.2%, as indicated by the post-test results. This training successfully improved the employees' pipe welding competencies, which are crucial for supporting the company’s operations.

Accurate backside boundary recognition of girth weld beads

Visual recognition of weld beads is essential for post-weld robotic grinding. The recognition of thin-walled weld bead boundary, especially the backside boundary, remains challenging due to the diverse features such as debris, misalignment, and deformation. Based on point cloud from a laser scanner, we present a robust and accurate backside boundary recognition method for girth weld beads of thin-walled pipes. A boundary point extraction method is designed based on an adaptive sliding window model. Without prior morphology features, the influence of misalignment and deformation on the accuracy of boundary point recognition is greatly reduced by the local model matching strategy. Leveraging the correlation among overall weld bead features, an anomalous boundary point recognition and correction method based on DBSCAN clustering is proposed to further enhance robustness. A series of validation experiments were conducted by the obtained backside point cloud data inside a girth weld pipe, and our proposed method showed a high accuracy and a high robustness to misalignment, deformation and debris features.

A Rapid Screening Method for Suspected Defects in Steel Pipe Welds by Combining Correspondence Mechanism and Normalizing Flow

A Rapid Screening Method for Suspected Defects in Steel Pipe Welds by Combining Correspondence Mechanism and Normalizing Flow

Application of Pattern Search and Genetic Algorithms to Optimize HDPE Pipe Joint Profiles and Strength in the Butt Fusion Welding Process

The rapid spread of the use of high-density polyethylene (HDPE) pipes is due to the wide variety of methods for connecting them. This study keeps pace with the developments of butt fusion welding of HDPE pipes by exploring the relationship between the performance of the weld joints by studying ultimate tensile strength and exploring the joint welding profiles by studying the shape of the joint at the outer surface of the pipe (height and width of the joint cap) and the shape of the joint at the internal surface (height and width of the joint root). Welding pressure, heater temperature, stocking time, and cooling time were the parameters for the welding process. Regression was analyzed using ANOVA, and an ANN was used to analyze the experimental results and predict the outputs. Two optimization techniques (pattern search and genetic algorithm) were applied to obtain the ideal operating conditions and compare their performance. The results showed that pattern search and genetic algorithms can determine the optimal output results and corresponding welding parameters. In comparison between the two methods, pattern search has a limited relative advantage. The optimal values for the obtained outputs revolved around a tensile strength of 35 MPa (3.45 and 4.5 mm for the cap and root heights, and 8 and 6.98 mm for the cap and root widths, respectively). When comparing the effects of welding parameters on the results, welding pressure had the best effect on tensile strength, and plate surface temperature had the most significant effect on the welding profile geometries.

Mechanism clarification and mitigation measures of radial deformation induced by girth welding of thin-walled pipes

Girth welding is extensively utilized in connecting pipeline structures. Excessive welding deformation may result in a decrease in ultimate bearing capacity and fatigue life. This research explores the characteristics and underlying mechanics of radial deformation in thin-walled girth welded pipes and proposes mitigation measures. Initially, several 304 stainless steel pipes were joined utilizing four distinct welding procedures. Welding deformation and residual stress distribution were measured using a 3D coordinate measuring machine (CMM) and the Cos α X-ray diffraction (XRD) method, respectively. Subsequently, numerical models were developed to simulate the welding process and verify the accuracy of the fusion zone, residual stress field, and radial deformation in the models. The mechanism of radial deformation was further elucidated based on the inherent strain method. The results show that the direction of radial deformation relies substantially on the hoop plastic strain. Hoop tensile plastic strain corresponds to radial outward deformation, while hoop shrinkage plastic strain corresponds to radial inward deformation. In addition, the influence of axial constraint on the formation process and results of hoop plastic strain, as well as the effect of heating zone width on radial deformation, was studied. Through simulation outcomes, the research suggests employing a regulated heat source method to mitigate radial deformation, which could potentially reduce deformation by 92.8%, offering considerable advantages in deformation mitigation and welding efficiency augmentation.

Microstructural, mechanical and nondestructive characterization of X60 grade steel pipes welded by different processes

Abstract In this paper, the welding quality of API 5L X60 steel pipes was investigated after the application of three different welding scenarios by applying submerged arc welding (SMAW), tungsten inert gas (TIG) and hybrid (TIG + SMAW) welding methods with an average heat input of ca. 1 kJ mm−1 for all passes. For this purpose, the ultrasonic and radiographic tests were done to detect possible discontinuities such as crack and porosity in the welding zones. In addition, the macro and microstructures of weld zones were made to examine different zones in terms of weld quality and phases. Moreover, the hardness, impact toughness and tensile tests were carried out to determine the mechanical properties of the weldments. The tensile strength of the pipe weldments was recorded to be ∼603, 610 and 625 MPa after the welding of pipes by SMAW, TIG + SMAW and TIG welding, respectively. In addition, the impact toughness of the welds was obtained to be 48, 76 and 66 J, for these welding methods, successively. According to the experimental findings, all three welding plans were successfully applied to the steel pipes and found to be suitable regarding the relevant international standards.

Continuous and synchronous calibration process of ovality and straightness for longitudinally submerged arc welding pipes with three rollers.

A new process of continuous and synchronous calibration process of ovality and straightness for LSAW (Longitudinally Submerged Arc Welding, LSAW) pipes with three rollers is proposed. Specifically, the process is introduced from three aspects: roller-shape, loading parameters and axial and circumferential deformation paths. The process is verified by numerical simulation and physical experiments. Further, the stress-strain in the Sections Ⅱ and Ⅳ is analyzed. The relationship between the process parameters and the residual ovality and residual straightness by experiments is discussed. The calibration scheme of LSAW pipes is put forward by using the control variable method. The results show that the shear stress is the principal stress direction in the Sections Ⅱ and Ⅳ. The residual ovality and residual straightness decrease with the increase of the radial reduction and times of reciprocating bending. The reciprocating bending process can eliminate the difference of the initial curvature, make the curvature of each section tend to be uniform. After calibration, the residual straightness is less than 0.2% and the residual ovality is less than 1%, demonstrating a good feasibility of this process.

Techno-economical comparative evaluation of diverse local heat treatment strategies for thick-walled pipe welds

Techno-economical comparative evaluation of diverse local heat treatment strategies for thick-walled pipe welds

Development and manufacturing of beryllium-armoring ITER enhanced heat flux FW toward series production in China

ITER’s enhanced heat flux (EHF) first wall (FW) provides thermal shielding to the other components behind it and limits its plasma boundary, consequently bearing high surface heat loads up to 4.7 MW m−2. China developed the EHF FW technologies in steady stages by making small mock-ups, semi-prototypes and a full-scale prototype (FSP), working toward series production at the Southwestern Institute of Physics. All the key technologies for bimetallic diffusion bonding, welding and assembly have been fully qualified. The Be armor tile size effects on thermal-fatigue performance have been evaluated using a pulsed high heat flux test with an EMS-400 electron beam facility. It was found that both the Be/CuCrZr bonding and its thermal-fatigue life are highly dependent on the tile size, and 12 × 12 mm2 Be tiles are acceptable for the required performance, either as individual tiles or in castellation by cutting larger ones. Small-scale mock-ups with such Be tiles survived 16 000 thermal cycles at 4.7 MW m−2, while EHF FW fingers with 16 × 16 mm2 Be tiles demonstrated unstable performance. In contrast, only BE tiles larger than 24 × 12 mm2 showed reliable diffusion bonding with the CuCrZr heat sink by hot isostatic pressing and consequently should be castellated into smaller ones. The manufacturing of the FSP finger goes through complex thermal cycles, using CuCrZr alloys in age-strengthening plus cold-rolling states, enabling it to maintain its tensile strength to the level of 285 MPa and its mean grain size less than 100 µm. The pipe welding for finger pairing and its assembly with the central beam are demonstrated, including enabling welding to be carried out twice for repair in a narrow space. The FSP showed good finger alignment, dimensional control and reliable vacuum tightness without any blockage of cooling channels.

Friction stir welding of AA6063 pipe: Effect of double pass on microstructure, strength and defects

Friction stir welding of AA6063 pipe: Effect of double pass on microstructure, strength and defects

Research on ultrasonic non-destructive evaluation algorithm for ultimate tensile strength of stainless-steel welded pipe welds based on width learning

ABSTRACT The regression prediction between ultrasonic signal and ultimate tensile strength of stainless-steel pipe weld is studied in this paper. First, ultrasonic signals were collected from the weld of AISI304 austenitic stainless steel welded pipe sample, and its ultimate tensile strength was tested. The data sets of ultrasonic signal and ultimate tensile strength of weld were constructed. The random forest algorithm is used to extract the characteristic value set of the ultrasonic signal set of the welding seam and reduce the dimension of the characteristic value set. Then, the set of eigenvalues after dimensionality reduction is input into the Bayesian BLS network for training. The results of the training were compared with those of other regression models. The results show that the model established by Bayes BLS algorithm is feasible and reliable to predict the ultimate tensile strength of stainless-steel pipe weld. The results also show that the model established by the Bayesian BLS algorithm has high accuracy and stability in predicting the ultimate tensile strength of stainless-steel pipe weld. This method can be used to predict the ultimate tensile strength of welds in different types of materials.

Analysis of Stress Distribution around the Weld Zone in High Frequency Resistance Welding of Steel Pipe

Analysis of Stress Distribution around the Weld Zone in High Frequency Resistance Welding of Steel Pipe

Influence of heat input and preheating on residual stresses in pipe weld

AbstractUsing finite element methods, residual stresses were estimated in pipe welds. Experiments were also conducted to verify the numerical results. An alternative to a three-dimensional model was used to simplify the numerical calculation for residual stresses investigation. Model predictions were validated by measuring residual stresses using X-ray diffraction. As compared to measured residual stress distributions, the computational approaches developed in this study can accurately predict welding residual stress distributions. The focused welding parameters have a significant impact on residual stresses even when all the other parameters are the same.

Analisis dan Upaya Preventif Risiko Tingkat Kebisingan Pekerjaan MEP (Mechanical, Electrical, Plumbing) Konstruksi Rumah Susun di Ibu Kota Negara

Construction work is one of the jobs that has various high risks for workers and people who are around it. These risks come from various sources, one of which is noise from various equipment and ongoing activities. One of the jobs that cause high noise in construction work is MEP (Mechanical Electrical Plumbing) work. Based on Permenaker Number 13 Year 2011, the Threshold Value (NAB) for noise that can be accepted by workers is 85 dBA for 8 hours a day. Based on the measurement of the construction of the flats, the MEP work in the form of Beam Separator Elevator Installation, Pipe Fabrication, Electrical Wiring Lighting Installation, as well as Welding and Grinding of Iron Pipe causes noise above the NAB. The highest noise comes from pipe fabrication in the form of iron pipe cutting activities using large grinding tools and bevel machines that produce noise of 107 dBA. From the Daily Noise Dose (DND) calculation, the noise generated from MEP work has a dangerous risk level for workers' hearing. Risk control efforts that can be done are preventive actions based on the K3 hierarchy in the form of administrative controls such as changing working hours or shifts and conducting safety talks before work is carried out. In addition, another preventive measure is the use of PPE such as ear plugs. Based on the calculation of the noise reduction level, the use of ear plugs has not reduced the noise level to reach the NAB, so it is recommended that workers in pipe fabrication work use ear muffs to reduce noise exposure.

Ultrasonic vibration assisted gas tungsten arc welding of Inconel 690 alloy: Ultrasonic effect to refine grains and improve mechanical properties

The Inconel 690 alloy is widely used in the manufacturing of nuclear equipment, such as pipe welding for steam generators (SG) and pressure vessels, due to its excellent high-temperature strength, corrosion resistance, and thermal stability. However, coarse grains have been observed in the welded joint of Inconel 690. Considering its crucial role as a structural material under high pressure, temperature, and corrosive conditions, improvements should be made to the microstructure of the welded joint. The ultrasonic-assisted gas tungsten arc welding (UA-GTAW) was used in Inconel 690 welding. The influence of ultrasonic vibration on the microstructure and mechanical properties of welded joints was studied. The results show that the ultrasonic refined the microstructure further to improve the mechanical properties. The UA-GTAW sample performed superiorities over regular GTAW joint in multi perspective including refined solidification grains, less element segregation, higher tensile strength and hardness. The Yield strength, ultimate tensile strength, and elongation increased from 320 MPa, 591 MPa, and 25.1 % to 387 MPa, 672 MPa, and 31.6 %, respectively.

The analytical model of crimping springback for large-diameter longitudinal welded pipe

The crimping technique is widely used in the manufacturing process of large-diameter longitudinal welded pipe. In the bending process, the springback is the critical problem affecting the shape, which is the key index of forming quality. So, crimping faces more challenges in accurate springback prediction for difficult-to-form metals such as pipeline steels and non-circular nature of the punch. This paper has established an analytical model of crimping springback for the longitudinal welded pipe. Firstly, the crimping process mathematical model which considered the impact of elastic modulus attenuation on springback calculation during plastic deformation is established, and the cross-section bending moment is calculated based on Hill’s bending theory. Secondly, a semi-analytical and semi-numerical method for calculating the crimping shape is presented. Finally, the comparison of the crimping shape of the real product shows that the calculation accuracy and efficiency of this method can meet the requirements of engineering applications. The relative error of the springback angle calculated by the analytical model is −5.84%, and the absolute error is 0.3°. This method can accurately predict the springback of longitudinal welded pipe after crimping and provide a reference for crimping process optimization.