Pipe Flange Joint Research Articles

Durability improvements of Exhaust pipe joints during operating Condition

Medium and Heavy Commercial Tipper vehicles in India are mainly used for off-road and mining applications where the vehicles are subjected to severe and irregular road load patterns. In such cases it is imperative that quality of weld joints in Exhaust pipes should be capable of withstanding off road duty cycle. The negative impact of any kind of defect will be magnified due to presence of such harsh road & environment conditions. The current paper focus discussion on the various failures and defects found in weld joints of exhaust pipes. Various methodology has been introduced to detect the modes of Weld failure. After detailed study and analysis, a set of recommendations are proposed for welding of Exhaust pipe flange joints to ensure high durability life of weld joints

Heat Loss Characteristics of Pipe Flange Joints: Experiments and Simulations

Abstract Sealing performance and heat loss are important factors for pipe flange joints (PFJs) subjected to medium or high temperatures. Heat loss is of great interest in practical engineering for uninsulated PFJs. Since an insulation layer may degrade the sealing performance of PFJs, heat loss of PFJs was tested and simulated considering various ambient temperatures of −10 °C, 0 °C, 10 °C, 20 °C, 30 °C, and 40 °C, with wind speeds of 0 m/s and 3 m/s and flange joint target temperatures of 200 °C, 300 °C, and 400 °C. It is worth noting that the experiments were performed during summer for high ambient temperatures and during winter for low ambient temperatures. As expected, the steady temperature slightly increases with the increase of external ambient temperature. For the same flange joint temperature, a 3 m/s wind speed decreases significantly the steady temperature, especially when the higher target temperature is applied. If the external wind speed is 3 m/s and the flange joint target temperatures are 200 °C, 300 °C, and 400 °C, respectively, the heat loss increases by approximately 38.4%, 30.7% and 23.6% when the ambient temperature changes from 30 °C to 10 °C. Moreover, the simulated temperatures agree well with the tested temperatures in most cases, and the average error is approximately 8%. The energy saving efficiency under the windless condition is approximately on average 26% higher than that with a wind speed of 3 m/s.

Bolted Pipe Flange Joint Assembly Man-hour Reduction and Related Problem

Bolted Pipe Flange Joint Assembly Man-hour Reduction and Related Problem

Behavior of gasketed bolted pipe flange joint under combined internal pressure, axial, and bending load: Three-dimensional numerical study

Optimized performance of joint is categorized by its “structural integrity” and “sealing capability”. In literature, limited data are available regarding the performance of gasketed bolted flanged joint under combined internal and external loading; hence an optimized joint performance cannot be addressed. In this paper, a detailed three-dimensional nonlinear finite element analysis of bolted gasketed flange joint is performed, to study its performance under combined internal (pressure) and external (axial and bending) load. Results of the finite element analysis are compared with the experimental results available in literature providing the validation of the numerical approach developed.

Evaluation of a Pipe–Flange Connection Method Based on Cold Work

The conventional joining method of a pipe and a flange uses welding. However, welded pipe–flange joints have the drawback with the inherent distortions and residual stresses resulting from the welding process, which can affect the mechanical integrity and performance of the flange significantly. In this study, a novel pipe–flange connection method based on cold work is evaluated using the finite element method. A weld neck flange is modified by manufacturing circumferential grooves at its internal surface and the pipe is cold worked into the grooves using a hydraulic expansion tool. The finite element model incorporates a pressure dependent friction model for the contact interaction between the tool–pipe–flange and a strain-based ductile failure locus for the pipe material accounting for ductile damage initiation during the cold work process utilizing a continuum damage mechanics approach. The finite element results show that a high load carrying capacity can be achieved for the cold work pipe–flange connection and has good potential for replacing the conventional welded joint.

Joint strength of gasketed bolted pipe flange joint under combined internal pressure plus axial load with different (industrial and ASME) bolt-up strategy

Gasketed bolted flange joints are used in process industry for connecting pressure vessels and pipes. Design procedures available in the literature mostly discuss structural strength, while sealing failure is still a big concern in industries. Similarly, limited work is found in the literature regarding performance of gasketed bolted joints under combined loading. A detailed 3D nonlinear finite element analysis is performed to study the strength and sealing of a gasketed bolted flanged pipe joint under different bolt-up strategy (Industrial and ASME) and under combined internal pressure and axial loading.

Investigation of Residual Stresses and Distortion in Welded Pipe-Flange Joint of Different Classes

ABSTRACT: Pipe and flange joints are commonly used in petrochemical, nuclear and process industries. Commonly, welding is used to make these joints which produces residual stresses and distortions. These stresses have detrimental effects on the structural integrity and service performance of the welded pipe joints. The objective of this study is to investigate the residual stresses and distortions during Gas Metal Arc Welding of pipe of schedule 40, nominal diameter 200 mm with different ANSI flanges of class numbers 150, 300, 600, 900, 1500, and 2500. Welding parameters including: voltage, current and heat as inputs were selected based on the literature available. The behaviour of the flanges of different classes is also discussed. In addition, the finite element methodology presented, in this paper, can be helpful for developing welding procedures for a range of pipe flange welded joint sizes in order to control the residual stresses and deformations. This will lead to optimised performance during bolt up and operating conditions.ABSTRAK: Paip dan sambungan flan biasanya digunakan dalam industri petrokimia, nuklear dan proses. Kimpalan menghasilkan tegasan sisa dan herotan, yang memberikan kesan yang merbahaya ke atas integriti struktur dan prestasi servis sambungan kimpalan paip. Objektif kajian ini adalah untuk mengkaji tegasan sisa dan herotan ketika kimpalan arka logam gas paip berjadual 40, diameter nominal 200mm dengan flan ANSI yang berbeza kelas # 150, 300, 600, 900, 1500, dan 2500. Parameter kimpalan termasuklah; voltan, arus dan haba input yang dipilih berdasarkan literatur sediada. Kelakuan flan yang berbeza kelas telah dibincangkan. Kaedah elemen finit yang dibentangkan adalah berguna dalam membangunkan prosedur kimpalan bagi julat saiz kimpalan flan paip unutk mengawal tegasan sisa dan canggaan i.e. bagi mengoptimakan prestasi ketika bolt up dan sedang beroperasi.                                                                 KEYWORDS: finite element; residual stresses; distortion; welding; pipe-flange joint; different classes

Numerical Investigation of Residual Stresses and Distortions due to Multi-Pass Welding in a Pipe-Flange Joint

This paper presents a numerical simulation for examining temperature fields, residual stresses, and distortions in multi-pass welding of a pipe-flange joint. A sequentially coupled transient non-linear thermo-mechanical three-dimensional finite-element model is developed to simulate four-pass tungsten inert gas welding process. An ANSI class 300{#} flange is welded with a 6 mm thick, 200 mm long, and 100 mm nominal diameter pipe, using a single V-groove butt joint with a 1.2 mm root opening. Goldak's double ellipsoidal model is used for the weld heat source, and inactive element addition technique is used for the addition of weld filler elements. Axial and hoop residual stresses and out-of-plane distortions along the flange face are plotted. In addition, welding start and end effects are discussed.

S1104-1-3 電動インパクトレンチによる管フランジの締付けについて([S1104-1]機械要素の設計・製造・応用技術(1))

Generally, bolts and nuts in bolted pipe flange assembly have been tightened using torque wrenches. On the other hand, recently, impact wrenches have been applied for tightening assemblies from working efficiency stand point In the use of the impact wrenches, since the value of tightening coefficient is bigger, it is necessary to take account the value of tightening coefficient when bolts and nuts in important bolted joints are tightened. In the present study, tightening method of nuts and bolts in bolted pipe flange joints is examined when impact wrench is used from FEM calculations and experiments. In this study, with an electric impact wrench, we performed the tightening experiment of the comparatively small size pipe flange, and FEM analysis was carried out for examining the axial tension characteristic. As a result, it is demonstrated that the scatter in bolt tightening forces using impact wrenches can be controlled as the same as that tightened using torque wrenches when the impact wrenches used is selected adequately and their tightening method is correct.

3D thermal finite element analysis of single pass girth welded low carbon steel pipe-flange joints

This paper presents a detailed computational procedure for predicting the complete thermal history including transient temperature distribution during girth welding and subsequent post weld cooling of low carbon steel pipe flange joints. Using the FE code ABAQUS, 3-dimensional non-linear heat transfer analysis is carried out to simulate gas metal arc welding (GMAW) process. ANSI Class #300 flange is used with a 6 mm thick, 200 mm long and 100 mm nominal diameter pipe. Joint type is a single ‘V-groove’ butt joint with a 1.2 mm root opening. FORTRAN subroutine is utilized for the application of volumetric heat flux from the weld torch using Goldak’s double ellipsoidal heat source model, which is based on Gaussian power density distribution. Temperature dependent thermal properties as well as phase change effects have also been accounted. Apart from comprehensive discussion on the thermal history, in-depth analysis of the axial temperature profile at four different sections on both sides of the weld joint is presented. The simulated results showed that the temperature distribution around the implemented heat source model is steady when the weld torch moves around the circumferential joint. The present simulation model can be used as a proper tool to investigate the effect of different GMAW process parameters.

Finite element simulation of mechanical stress relieving in welded pipe—flange joint

The mechanical stress relieving (MSR) treatment is commonly employed as post-weld stress relieving process in pressure vessels. Its application to piping system is rarely reported in the literature. This article presents a three-dimensional finite-element analysis for MSR in welded pipe—flange joint of carbon—manganese steel. Sequentially coupled transient, non-linear thermo-mechanical analysis for single pass gas metal arc welding is first performed to calculate welding residual stresses. Subsequently, separate parametric studies for three different types of MSR loads including internal pressure, external pressure, and axial pull are performed on the pre-stressed model and stress-relieving behaviour is studied. The method of post-weld MSR has found an effective way for mitigation of the residual stresses in the piping systems. It is concluded that both the internal pressure and the axial pull have significant effect on the residual stresses on the inner surface of the joint.

Numerical simulation of mechanical stress relieving in a multi-pass GTA girth welded pipe–flange joint to reduce IGSCC

Welding of piping components produces highly non-uniform residual stresses in the weldment which consequently affect material structural response under loading and also expedite origination/propagation of defects such as stress corrosion cracking and brittle fracture. For welding-induced residual stresses, mechanical stress relieving (MSR) is one of the mitigation techniques to improve the service life of pressure vessel components. However, its application to piping systems is rarely reported in the literature. This paper presents a two-dimensional axisymmetric finite element model of a pipe–flange joint subjected to a multi-pass girth welding followed by an MSR process. Sequentially coupled non-linear transient thermo-mechanical analysis for multi-pass gas tungsten arc welding is first performed to calculate welding residual stresses. Subsequently separate parametric studies for three different types of MSR load including internal pressure, external pressure and axial pull are performed on the pre-stressed model, and stress relieving behaviour is studied. It is concluded that both the internal pressure and axial pull have a significant effect on residual stresses on the inner surface of the joint.

Numerical simulation to study the effect of tack welds and root gap on welding deformations and residual stresses of a pipe-flange joint

This paper presents a three dimensional sequentially coupled non-linear transient thermo-mechanical analysis to investigate the effect of tack weld positions and root gap on welding distortions and residual stresses in a pipe-flange joint. Single-pass MIG welding for a single ‘V’ butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI flange class # 300 of low carbon steel is simulated. Two tack welds at circumferentially opposite locations, with the crucial effect of the tack weld's orientation from the weld start position is the focus in this study. Four different angular positions of tack welds (0 and 180°, 45 and 225°, 90 and 270°, 135 and 315°) are analyzed. In addition, four cases for root gaps (0.8, 1.2, 1.6, 2.0 mm) are considered and computational results are compared. A basic FE model is also validated with experimental data for temperature distribution and deformations. From the results, the axial displacement and tilt of the flange face are found to be strongly dependent on the tack weld orientation and weakly dependent on the root gap.

Numerical simulation of the effect of constraints on welding deformations and residual stresses in a pipe–flange joint

This paper presents a detailed three-dimensional finite element (FE) study to investigate the effect of mechanical constraints on welding distortions and residual stresses in a pipe–flange joint. The FE model of a pipe–flange joint is subjected to sequentially couple nonlinear transient thermo-mechanical analysis to simulate complex welding phenomena. Single-pass gas metal arc welding for single ‘V’ butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI flange class #300 of low carbon steel is simulated. Two tack-welds at 90° and 270° from the weld start position are modelled. Four different constraint conditions representing the welding of unassembled joints, welding of assembled joints, welding of assembled joints with reflective symmetry and welding of perfectly constrained joints are analysed. To model the constraints and boundary conditions more realistically contact pairs are used between the matching surfaces of different structural components. Basic FE models are validated with experimental data for temperature distribution and deformations. Predicted welding distortions and residual stresses are compared and discussed in detail. From the results, axial displacement and tilt of the flange face are found to be strongly dependant on the constraint conditions. Minimum axial distortion on the flange face is found for rigidly clamped flanges. However, residual stresses have a weak dependence on the constraints set.

3-D Finite Element Simulation of Welding Residual Stresses in Pipe-Flange Joints: Effect of Welding Parameters

This paper presents results of detailed three-dimensional finite element simulation of residual stress distribution in welded Pipe-Flange Joints with emphasis on the effect of welding parameters and geometrical size of the model. Single-pass Metal Inert Gas welding with single “V” Butt-weld geometry is used in the study. The effect of two basic welding parameters including welding current and speed and two geometrical parameters i.e. pipe diameter and wall-thickness are examined. For both welding current and welding speed, three sets of parameters comprising of low, medium and high values are used. To analyze the effect of each parameter explicitly only one parameter is changed at one time. In most of the cases 100 mm nominal pipe diameter is used. A FE Model for 200 mm nominal pipe diameter is also analyzed to determine the effect of pipe diameter.

Finite-element simulation of tack welds in girth welding of a pipe-flange joint

Welding deformations play an important role in sealing capabilities and service life of welded pipe-flange joints. A numerical procedure for modeling of tack welds in girth butt-welding of such joints is of vital importance for the prediction of transverse shrinkage and flange face deformation, which is directly related to the joint sealing capability. This paper presents a 3-D finite element simulation of a pipe-flange joint to describe the numerical procedure for modeling of tack welds in circumferential joints. Sequentially coupled nonlinear transient thermo-mechanical analysis is performed to simulate Metal Inert Gas (MIG) welding. Single pass butt weld geometry with single “V” for 100 mm nominal diameter pipe with same sized weld neck type ANSI flange of class no. 300 is used. Temperature dependent material properties are used and deposition of filler metal is obtained by element birth and death feature. The peak temperature of the tack during the butt-welding of the tacked model is concluded a key parameter for numerical prediction of deformations, whereas tack temperature has negligible effect on the residual stresses.

Prediction of welding distortions and residual stresses in a pipe–flange joint using the finite element technique

This paper presents a comparative study of three- and two-dimensional axisymmetric finite element (FE) analyses of a welded pipe–flange joint for residual stresses and deformations in order to identify their merits or demerits. Sequentially coupled thermal stress analysis is performed to simulate single pass metal inert gas welding. Butt weld geometry with a single ‘V’ for a 100 mm nominal diameter pipe and same sized weld neck type ANSI class #300 flange is used. The heat input is modelled by using the Goldak double ellipsoidal heat source model. Temperature dependent material properties are used and deposition of filler metal is obtained by element birth and death feature. Both thermal and structural FE models are validated with experimental measurements. Residual stresses predicted by two-dimensional model are generally on the higher side and hence more conservative. However, we conclude that the three-dimensional FE model is preferable for the prediction of flange face distortion since it is a vital parameter for flange joint performance.

332 内部熱流体を受ける管フランジ締結体の熱応力解析と密封性能評価(O.S. フランジガスケット締結体の力学と密封性能評価II)(フランジガスケット締結体の力学と密封性能評価)

332 内部熱流体を受ける管フランジ締結体の熱応力解析と密封性能評価(O.S. フランジガスケット締結体の力学と密封性能評価II)(フランジガスケット締結体の力学と密封性能評価)

326 内圧を受ける管フランジ締結体の応力解析と密封性能評価(O.S. フランジガスケット締結体の力学と密封性能評価I)(フランジガスケット締結体の力学と密封性能評価)

326 内圧を受ける管フランジ締結体の応力解析と密封性能評価(O.S. フランジガスケット締結体の力学と密封性能評価I)(フランジガスケット締結体の力学と密封性能評価)

Experimental and Numerical Study of Multi-Pass Welding Process of Pipe-Flange Joints

Residual deformations of pipe-flange joints due to thermal strains caused by the multi-pass welding procedure in a manufacturing process are investigated both experimentally and numerically (FEM). To avoid any risk of leakage between two mounted pipes using flange joints, geometrical distortions (twisting) of the flange must be prevented. How the flange is distorted depends both on the groove shape and the weld sequence used. However, to be spared from machine work after the welding process, the distortions have to be minimized. A casting-technique has been developed in order to measure the twisting of the flange after each weld pass. Also, measurements of the residual radial deflection of the pipe have been performed.