A Case Study of Gas Leakage and Assessment of Mechanical Properties With Welding Variables in Fillet Weldment of Small Diameter Pipe

2006 ◽  
Author(s):  
Jong-Hyun Baek ◽  
Woo-Sik Kim
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Natural Gas ◽  
Weld Zone ◽  
Branch Pipe ◽  
Small Diameter ◽  
Welding Process ◽  
Pipe Diameter ◽  
Pipe Material ◽  
Gas Leakage

A branched pipe joint has been employed to execute the pressure control, condition check, purgation, and distribution of the gas in the natural gas facilities. Installation of branch pipes is generally done through the welding work, and as a welding process, the weldolet and the sockolet are used. During the maintenance working of in-service natural gas pipeline, there was gas leakage in sockolet weldment. The causes of incident were investigated with various tests. We found the wrong pipe material, the weld defect and the non-destructive test limitation of fillet weldment as the reasons of gas leakage. As the follow-up measures, it was done to assess the soundness depending upon the configuration of the weld zone, a change in the welding process and a change in the pipe diameter by assessing the mechanical properties of the sockolet weld zone and further to assess comparatively the mechanical performance of the sockolet weld zone and that of the weldolet weld zone. In the sockolet weld, the tensile strength showed no difference and the fatigue strength showed a difference depending upon a change in the welding process. In the case that the leg length of the weld zone was made lengthwise in the direction of the branch pipe, the SMAW welding work compare with the GTAW, the sectional area of the weld zone was more increased, and the pipe diameter was more increased, the fatigue strength was increased.

Effects of bottom plate in friction stir welding of AA6061-T6

2020 ◽  
Vol 118 (1) ◽  
pp. 108
Author(s):  
M.A. Vinayagamoorthi ◽  
M. Prince ◽  
S. Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Axial Load ◽  
Weld Zone ◽  
Welding Process ◽  
Bottom Plate ◽  
Welding Parameters ◽  
Nugget Zone ◽  
Friction Stir ◽  
Weld Joints ◽  
Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

Investigation on the effects of the joint type on the driven out bead in the welded pipes produced by high-frequency induction welding

2020 ◽  
pp. 146442072097343
Author(s):  
M Ghaffarpour ◽  
D Akbari ◽  
H Moslemi Naeini
Keyword(s):  
Mechanical Properties ◽  
Weld Joint ◽  
High Frequency ◽  
Weld Zone ◽  
Welding Process ◽  
Solid Material ◽  
Outer Diameter ◽  
Metallurgical Properties ◽  
Semi Solid ◽  
High Frequency Induction

In this paper, the effects of the joint type on the driven-out bead of the roll-formed pipes, welded by high-frequency induction welding process are studied. The main goal is to predict and reduce the volume of the bead driven out in the weld seam. Moreover, it aims to move the semi-solid bead during welding to the outer diameter of the pipe. This study has two prior aims: to produce a defect-free joint and to improve the mechanical and metallurgical properties. In order to optimize the weld joint, various joint types have been investigated by experimental tests and simulation. Lastly, destructive tests were used to determine if the desired mechanical properties of the weld joint were obtained. The metallurgical properties and the derivation of the semi-solid material in the weld zone have both been investigated in terms of microstructure. According to the results, the proper joint type improves the mechanical properties by 5% and reduces the volume of the weld bead about 45%.

Studies on cold metal transfer welding of aluminium alloy 6061-T6 using ER 4043

2020 ◽  
Vol 234 (7) ◽  
pp. 924-937
Author(s):  
R Pramod ◽  
N Siva Shanmugam ◽  
CK Krishnadasan
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloy ◽  
Pressure Vessel ◽  
Weld Zone ◽  
Welding Process ◽  
Metal Transfer ◽  
Welding Parameter ◽  
Cold Metal Transfer ◽  
Cold Metal ◽  
Alloy 6061

Aluminium alloy 6061-T6 is utilized in aerospace industry for developing pressure vessel liner. Cold metal transfer is a promising welding process used in fabricating aluminium structures. The present work is focussed to achieve an optimum welding parameter for joining a 3.5-mm thick pressure vessel and to examine the mechanical properties and metallurgical nature of the weldment. The welded joint was evaluated as defect free using radiography test. The joint efficiency (66.61%) and measured microhardness of weldment (59.78 HV) exhibited promising results. The effect of grain coarsening in the heat affected zone (HAZ) and weld zone is attributed to the thermal gradients during welding. Dissipation of small amounts of strengthening elements Si and Mg during welding leads to reduction in mechanical properties. X-ray diffraction peaks revealed the presence of intermetallic Al–Si and Fe–Si in the weld zone. Fractography examination confirms the ductile type of failure in the fractured surface of the tensile samples.

Small Diameter Remote Field Eddy Current Inspection for Unpiggable Pipelines

2005 ◽  
Vol 127 (3) ◽  
pp. 269-273 ◽  
Author(s):  
Albert Teitsma ◽  
Stephen Takach ◽  
Julie Maupin ◽  
Jennifer Fox ◽  
Paul Shuttleworth ◽  
...  
Keyword(s):  
Natural Gas ◽  
Eddy Current ◽  
Small Diameter ◽  
Pipe Diameter ◽  
Free Swimming ◽  
Eddy Current Inspection ◽  
Excellent Candidate ◽  
Natural Gas Transmission ◽  
Prototype Design ◽  
Transmission Pipelines

In-line inspection tools cannot inspect most of the natural gas transmission pipelines and distribution mains due to restrictions in the pipelines that will not allow a tool equipped with current inspection technologies to pass. Remote field eddy current (RFEC) inspection is an excellent candidate for inspecting a pipeline with multiple diameters, valve and bore restrictions and tight or miter bends. The results of this paper show that the RFEC technique can inspect pipeline materials, and that all of the components needed for RFEC inspection can be made much smaller that the pipe diameter. RFEC inspection is commercially available for inspecting small diameter piping without restrictions, several hundred feet at a time. The prototype design described in this paper shows this technology will work in a free-swimming tool that can inspect miles of pipeline at time and bypass restrictions.

Mechanical Response and Performance Relationship of X70 Pipeline Steel with Weld Zone

2020 ◽  
Vol 993 ◽  
pp. 622-627
Author(s):  
Gang Wu ◽  
Peng Zhang ◽  
Jin Heng Luo ◽  
Li Feng Li ◽  
Guang Da Xu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Mechanical Response ◽  
Pipeline Steel ◽  
Weld Zone ◽  
Safety Evaluation ◽  
Welding Process ◽  
Local Deformation ◽  
Uniaxial Tensile ◽  
High Flux ◽  
X70 Pipeline Steel

With the development of the natural gas industry, high flux natural gas pipelines will cause local deformation because of pressurization, which has an important effect in the service safety of pipeline materials. In this paper, the X70 pipeline steel with weld zone was studied, and the tensile test was used to simulate the uniaxial tensile stress. The results showed that the strain was mainly concentrated in the weld zone, which can imply that the weld zone has high strain hardening ability. The heat-affected zone with poor internal structure was prone to breakage. The research results can provide theoretical basis and experimental basis for pipeline steel welding process design and safety evaluation under high flux conditions.

scholarly journals Repair Welding of the Tunnel Defect in Friction Stir Weld

2018 ◽  
Vol 37 (7) ◽  
pp. 675-681 ◽  
Author(s):  
Weipo Li ◽  
Zhimin Liang ◽  
Congwei Cai ◽  
Dianlong Wang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Weld Zone ◽  
Welding Process ◽  
Friction Stir Weld ◽  
Strength Increase ◽  
Repair Welding ◽  
Friction Stir ◽  
Longitudinal Residual Stress

AbstractThe tunnel defect formed in friction stir weld would dramatically push the mechanical properties of joints into deterioration. In this study, friction stir welding process was adopted to repair the joints of 7N01 aluminum alloy with tunnel defect. The effects of friction stir repair welding process on the microstructure and mechanical properties were comprehensively investigated. Microstructure of the repaired joints shows that the grain size in nugget zone decreases slightly while the recrystallization in the retreating side of thermo-mechanically affected zone is intensified as the joints are repaired. The microhardness of the repaired joints declined slightly compared with the defective joint. However, the yield strength and tensile strength increase and recover to the values of the joints free of defect. The longitudinal residual stress in weld zone increased remarkably as the repair times increase. Compared with the once repaired joint, yield strength and tensile strength of the twice repaired joint reduced slightly, and the throat thickness also reduced during the repeated repair welding process. Therefore, the times of repair welding applied should be limited actually.

Microstructure and Mechanical Properties of GMAW Welded Joints Er-Containing Aluminum Alloy

2020 ◽  
Vol 993 ◽  
pp. 92-99
Author(s):  
Hao Zhen Guo ◽  
Li Cui ◽  
Hui Huang ◽  
Xiao Guo ◽  
Ding Yong He
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Penetration Depth ◽  
Welded Joint ◽  
Weld Zone ◽  
Welding Process ◽  
Welding Current ◽  
Depth Range ◽  
Arc Voltage ◽  
Microstructure And Mechanical Properties

This present work explored the welding process of gas metal arc welding for 4mm 5E61 Er-containing aluminum alloy, and then analyzed the microstructure and mechanical properties of the welded joint. The results demonstrated that when the welding current was 160A-220A, the welded joint penetration depth range was 5.75mm to 6.72mm, the melting width ranging from 9.68mm to 11.61mm. When the arc voltage increased from 17.5V to 22.5V, the penetration depth of the welded joint reduced from 6.95mm to 5.57mm, and the melting width ranged from 6.64mm to 11.86mm. When the welding current was 170A, the arc voltage was 17.5V, and the welding speed was 10mm/s. In the third case, a fully penetrated welded joint can be obtained and the joint strength was the highest value. The yield strength reached 192 MPa, the tensile strength can be 301 MPa, and the fracture location occurred in the HAZ. The weld zone of the welded joint mainly consist of the equiaxed dendrites size of 50 μm. The micro-hardness of the weld zone was lower than that of the base metal, and there was no obvious softening phenomenon in the heat affected zone.

scholarly journals Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel

10.30544/545 ◽  
2020 ◽  
Vol 26 (3) ◽  
pp. 279-292
Author(s):  
Akash Doomra ◽  
Sandeep Singh Sandhu ◽  
Beant Singh
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Electron Beam ◽  
Ferritic Stainless Steel ◽  
Electron Beam Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The applicability of ferritic stainless steel is restricted due to its low weldability, and this can be attributed to the severe grain growth in the weld zone during the solidification of the weld pool and formation of fully ferritic structure. This study aims to investigate the weldability of 18 mm thick AISI 409 ferritic stainless steel plates using an electron beam welding process without the use of filler metal. The joints were investigated for metallography characterization (microstructure, macrostructure, and microhardness) and mechanical behavior (tensile strength and impact toughness) in as-welded condition and after post-weld heat treatment at 550 ºC for 75 minutes. The weld zone exhibited large columnar grains in the direction perpendicular to the weld centerline and got refined after post-weld heat treatment. The ultimate tensile strength, yield strength, and microhardness of the weld zone were found higher than the base metal. The impact toughness of weld zone was found to be reduced by 45%, but the post-weld heat treatment improved the toughness by 40%. Results revealed that the electron beam welding process could be successfully employed for welding of AISI 409 ferritic stainless steel, which will increase its application range that requires thicker section of welded plates. Post-weld heat treatment was found to be advantageous for improving the microstructure and mechanical properties.

scholarly journals Friction welding of carbon quality steel

2021 ◽  
Vol 2131 (4) ◽  
pp. 042062
Author(s):  
V Schepkin ◽  
Yu Poletaev
Keyword(s):  
Experimental Study ◽  
Friction Welding ◽  
Power Plants ◽  
Branch Pipe ◽  
Small Diameter ◽  
Welding Process ◽  
Economic Feasibility ◽  
Technical Problems ◽  
Carbon Quality ◽  
Conical Surfaces

Abstract The aim of the work is to study the possibility of using, instead of manual arc welding with a covered electrode, a method of friction welding of fittings and small-diameter branch pipes of hull power plants. The solution to this problem is possible on the basis of the application of the friction welding process of small diameter nipples and nipples. Given the insufficient theoretical and experimental study of the problem, it was necessary to solve the following scientific and technical problems: to develop the design of the models and the connected (conical) surfaces of the choke and branch pipe assemblies; substantiate the choice of optimal angles for preparing surfaces for welding; justify the choice and experimentally confirm the values of the welding mode parameters; to assess the quality of welded joints by non-destructive and destructive methods. The obtained positive results of the experimental study confirmed the technological feasibility and economic feasibility of using friction welding of carbon steel fittings and small-diameter nozzles.

scholarly journals Mechanical Properties Of Butt Welded AZ31B Magnesium Alloys

2021 ◽  
Author(s):  
MD. S.M. Chowdhury
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fatigue Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Welding Process ◽  
Fusion Welding ◽  
Friction Stir ◽  
Brittle Phase ◽  
Welding Defect

Mechanical properties of friction stir welded (FSWed), double sided arc welded (DSAWed), fiber laser welded (FLWed) and diode laser welded (DLWed) on AZ31B Mg alloy were studied. After welding, grains at the centre became recrystallized. Brittle phase β-Mg₁₇AI₁₂ particles observed at the centre of the joint during fusion welding process. The yield strength (YS), ultimate tensile strength (UTS) and fatigue strength were lower in the FDWed samples than in the DSAWed samples. Welding defect at the bottom of the FDWed joint was observed when right hand thread (RHT) weld tool was considered. In FLWed joint, YS, UTS and fatigue strength, with a joint efficiency of ~91% was achieved while the YS, UTS and fatigue strength of the DLWed joints were notably lower. The DSAWed joints and DLWed joints exhibited a higher strain hardening capacity in comparison with the FSWed joints and FLWed joints, respectively.

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