Management of thermal process for polyethylene gas pipes welding with built-in heater
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Abstract:
Abstract Based on the thermal process control, rapid welding technology for polyethylene pipes with built-in heater in the open air at temperatures below standard is proposed. Technological parameters of welding are determined by calculation from the condition of temperature field dynamics in heat-affected zone according to regularities, that are peculiar to welding at permissible temperatures. The results of determining the welding parameters during electrofusion welding and welding of the saddle branch to the polyethylene pipe of the gas pipeline, as well as the results of tests of the joints obtained by the proposed welding technology are presented.Keywords:
Electrogas welding
Explosion welding
Plastic welding
The process of joining thin-walled small-diameter pipes made of aluminum alloys using welding has some special aspects to it. Volumetric analysis shows occurrence of welding defects in the form of cracks, pores and oxide inclusions that are inadmissible according to the requirements of technical standards. This paper discusses a process for welding heat pipes to be used in rocket and space hardware, as well as presents solutions for scientific and technological problems encountered in the course of their making, such as: • Methods of preparing parts for welding and the process of welding composite members of heat pipe structure made of aluminum alloys with the use of special tooling; • An illustrative example of using effective creative assembly of pipes for welding with the use of a coolant which provides additional removal of heat from the area of the welded joint; • A well-chosen automated mode of welding fixed joints between thin-walled pipes using modern main and auxiliary welding materials and an inert protective gas that has a high degree of purification owing to a reduction of its contaminants content and its storage in bottles of an advanced design; • Use of a welding wire made to special specifications and stored in specialized vacuumed bags made of polyethylene film; • An analysis of possible methods of welding heat pipes and development of the best process for their welding that takes into account the physical, chemical and mechanical properties of the material and special operational aspects of structure. Key words: sealing of heat pipes, fixed joints between pipes, aluminum alloys, thin-walled small-diameter pipes
Explosion welding
Fusion welding
Plastic welding
Friction Welding
Electrogas welding
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This article introduces joint type of copper-aluminum pipe,including straight pipe butted joint,flared pipe insert joint,reducing pipe insert joint and reducing pipe lap joint,and the welding technologies in domestic and abroad,including friction welding,energy storage welding,flash welding,resistance welding,braze welding,cold butt welding and ultrasonic welding.Electric resistance welding is considered to be better welding method in domestic,which possesses many advantages,such as simple welding principle,easy welding procedure,and re-process is not required after welding,etc..
Cold welding
Flash welding
Welding power supply
Butt welding
Plastic welding
Welding joint
Electrogas welding
Friction Welding
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The properties of full thickness repair welding seam that generated by 6 kinds of welding material under the same repair welding condition were comparatively investigated by V-notch Charpy impact toughness test, micro-hardness test and tensile test, and selected out the repair welding material matching with better weld performance. Taking the selected welding material as special welding material for manual repairing the weld defect in 准1 219 mm ×18.4 mm X80 M SAWH pipe, the full thickness repair welding tests for the different welding process parameter were conducted, and the low temperature impact test for repair weld was carried out. Finally, it determined the repair welding process for 准1 219 mm×18.4 mm X80 M SAWH pipe. The results indicated that the SHJ557 welding electrode produced by Shanghai Welding Equipment Factory is more suitable for the above repair welding process of 准1 219 mm ×18.4 mm X80 M SAWH pipe, the various performance indexes are higher; the determined repair welding process parameters are reasonable, it ensures the quality of repair weld and the mass production of steel pipe.
Charpy impact test
Electrogas welding
Plastic welding
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Single-wire pulsed MIG welding test was used on 6005A Aluminum alloy lap joints with CLOOS special welding robot.The microstructure,welding heat inputting,stress were comprehensively analyzed for post-welding cracks universal occurred on the weld toe.Sysweld software was used to simulating welding heat,welding temperature field and stress field.Results of test and simulation showed that,welding heat inputting excessive and welding angle inconsequence,which induced part heat concentrated was the essential causes of cracks on 6005A Aluminum alloy lap joints.Assembly gap cause stress concentration was an important induced factor in welding cracks expanding and extension.Welding cracks were effectively controlled through optimizing welding parameter,adjusting welding angle and enhancing assembly effect,which assure the quality of production.
Welding joint
Upset welding
Electrogas welding
Plastic welding
Robot welding
Cold welding
Lap joint
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At present,there are shortcomings of welded structure deformation,poor welding quality and low performance in the welding of stainless steel sheet. In order to further improve sheet metal welding process,welding deformation factors were reviewed in the article. After a brief introduction of common plate deformation,the impact of welding deformation from input heat,weld size,initial roughness,thickness,welding assembly and other factors were focus described. And further distortion of welding temperature field or enhancement of welding structure stiffness were presented in the article,an auxiliary source of heat or cold,fixtures constraints,the device of rotating extrusion were designed to reach sheet deflection control purpose. The article notes that the application of finite element simulation technology in the welding will more scientifically analyze and predict welding deformation.
Friction Welding
Plastic welding
Electrogas welding
Cold welding
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Spot welding
Cold welding
Electrogas welding
Plastic welding
Upset welding
Flash welding
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Interlayer plays an important role in improving the welding quality of explosive welding. In this study, four different welding interfaces were subjected interlayer explosive welding to demonstrate advantages of interlayer explosive welding over direct welding. The results indicated that using an interlayer in explosive welding could reduce excessive melting, enlarge the weldability window, reduce the vortex region, and reduce the large plastic deformation between interfaces. Smoothed particle hydrodynamics (SPH) simulations were used to simulate the different welding processes, which provided information on the interface morphology, temperature, melting, and pressure. The simulated results were found to correlated very well with the experimental results.
Explosion welding
Weldability
Plastic welding
Cold welding
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Up to now,the welding joints of P92 steel pipes have been all repaired in China by the matching welding materials.A test study was carried out on repairing the welding joints of P92 steel pipes by nickel welding materials,in case of the matching welding materials are not available on the site.The welding was done by using the welding technique dedicated for P92 steel pipes on the site and the repairing was performed after heat treatment by use of nickel welding materials.The results indicate that it is feasible to use nickel welding materials for repairing,but further study is needed on its high temperature time-dependent performance and the long-term strength performance.
Flash welding
Plastic welding
Electrogas welding
Friction Welding
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This paper is about the application of welding robot in the melting of major seams of aluminum plate-fin heat exchanger.By optimizing the welding process of robot,single-layer welding of robot takes the place of manual double-layer welding,as a result,the welding penetration can reach 4.0-4.5 mm and the welding speed can reach 350-500 mm/min.In addition,through burst test and pulsation test,the welding strength is found to meet the design requirements of aluminum plate-fin heat exchanger.What's more,the welding appearance is good and the quality is stable and reliable.This application also reduces the labor intensity of workers.
Robot welding
Upset welding
Explosion welding
Fin
Electrogas welding
Plastic welding
Butt welding
Friction Stir Welding
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According to the character of stainless clad steel plate 14Cr1MoR+347H,in order to avoid cold-cracking during the welding,and to assure each characteristic of design welding requirement,welding material,welding process and heat-treatment process were chosen and made properly,and gained successfully during the actual manufacturing.
Plastic welding
Explosion welding
Electrogas welding
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